Dianne Unsain
email: dianneunsain@gmail.com

Vincent Buccio
email: vincent.buccio@le04.fr

Pierre Magniez
email: pierre.magniez@univ-amu.fr

Zooarchaeology, Medieval Economy and Culinary Practices: the Case of Petra Castellana Castrum (South of France)

Keywords:

Through the work of historians and zooarchaeologists, French medieval butchery, its regulations, skills, prices and products offered for sale are well known, especially from the 13 th and 14 th centuries. Nevertheless, the consumer of the high Middle Ages as well as his culinary practices are relatively unknown. This zooarchaeological study of Petra Castellana castrum (11 th -12 th centuries AD), in particular bone density and animal utility indices, has shed light on the supply systems and culinary practices of an area of the site. The contribution of textual sources has also been decisive in contextualizing and interpreting the results. This paper puts forward the preparation of two different types of meat cuts: (1) a preliminary cut favouring equally sized pieces of meat, followed by (2) a cooking cut which, on the contrary, was adapted to the different kinds of meat.

INTRODUCTION

Since the 1970s, medieval urban economy has generated a strong interest among European historians, particularly in issues related to animal products/by-products and culinary practices. Consequently, many studies have emerged (e.g., [START_REF] Montanari | Alimentazione e cultura nel Medioevo[END_REF]1993;[START_REF] Flandrin | Food: a culinary history from Antiquity to the present[END_REF][START_REF] Adamson | Food in medieval times[END_REF]Woolgar, 2006;[START_REF] Lewicka | Food and foodways of medieval Cairenes: aspects of life in an Islamic metropolis of the eastern Mediterranean[END_REF][START_REF] Gautier | Cooking and cuisine in late Anglo-Saxon England[END_REF][START_REF] Montanari | Medieval tastes: food, cooking, and the table[END_REF]. The south of France has benefitted from this trend with, for example, the work of [START_REF] Sclafert | Cultures en Haute-Provence : déboisements et pâturages au Moyen Âge[END_REF], [START_REF] Stouff | Ravitaillement et alimentation en Provence aux XIVe et XVe siècles[END_REF]), Ferrières (2002), Horard and Laurioux (2017) or Petrowiste and Lafuente Gómez (2018). Subsequently, advances in medieval zooarchaeology through international studies such as those of [START_REF] Baker | Le rôle de la chasse comme moyen de subsistance durant le haut Moyen Âge dans le nord de l'Italie : une comparaison des sources zooarchéologiques et historiques[END_REF], [START_REF] Bartosiewicz | Cattle trade across the Danube at Vác (Hungary)[END_REF], Albarella (2005) or [START_REF] Grau-Sologestoa I | Livestock management in Spain from Roman to post-medieval times: a biometrical analysis of cattle, sheep/goat and pig[END_REF] have nuanced or completed the information provided by textual sources. Substantial research in southern France such as that of [START_REF] Forest | Vestiges fauniques osseux du Xe au XIVe siècle en Rhône-Alpes[END_REF], [START_REF] Leguilloux | L'archéozoologie et l'interprétation des sites : recherches archéozoologiques sur la Provence romaine et médiévale[END_REF], [START_REF] Catalo | Déchets de boucherie et alimentation au XlVe siècle à l'hôpital du pas à Rodez (Aveyron)[END_REF][START_REF] Forest | Approches bioarchéologiques de l'habitat castral languedocien -Huit sites de la bordure méridionale du Massif central (Xe -XVIe siècle)[END_REF], [START_REF] Rodet-Belarbi | Alimentation carnée du XIVe au XVIe siècle dans le sud de la France, d'après les sources archéozoologiques : la part des mammifères sauvages et des oiseaux[END_REF] and [START_REF] Bertin | The exploitation of equids in the middle ages on the Clos d'Ugnac archaeological site (Pennautier, Aude, France)[END_REF] has largely been inspired by the work of [START_REF]Ossements animaux du Moyen-Âge au Monastère de La Charité-sur-Loire[END_REF] although hers was not about the south of France. In this context, urban supply issues, changes in food choices and regional culinary practices have been at the very core of discussions. These considerations have highlighted two main points. First, the incredible complexity and diversity of these phenomena, making it extremely difficult (if not impossible) to propose a recurrent pattern between periods, regions or settlement types.

Secondly, issues and biases in archaeology and history are different. For example, zooarchaeology is able to fill in the gaps in textual sources for periods preceding the 13 th -14 th centuries AD and to verify and complete the available data. Nevertheless, it can hardly address some topics such as trade, regulations and cooking. It will necessarily have to rely on posterior texts (or iconography) to contextualize its results, thus exposing itself to anachronisms. These obstacles are inherent. Yet, bringing these two disciplines together is crucial to the study of medieval societies.

In this way, Provençal butchery, its rules and skills as well as its prices and the products offered for sale, are well known. Nevertheless, whether from textual or material sources, consumer-specific information is very often supplanted by that of the butcher: archives overwhelmingly collect legislative texts aimed at regulating and standardising meat selling or refer to complaints which bear witness to the tensions between butchers and local authorities [START_REF] Stouff | Ravitaillement et alimentation en Provence aux XIVe et XVe siècles[END_REF]Ferrières, 2002;[START_REF] Petrowiste | En passant par le mazel. Acheter sa viande au quotidien en France méridionale à la fin du Moyen Âge[END_REF]. In addition, the methods applied by zooarchaeologists may be biased because it is difficult to determine whether the meat diet was marked by a production/consumption dynamic or only consumption. This issue is even more crucial when the context is not clearly identified as urban. Thus, several questions arise: was the site supplied by a butcher or through private production? If from a butcher, was it a travelling butcher who slaughtered and butchered the animals? A major underlying question lies behind these issues: were carcasses consumed entirely by a single household or were they shared among the inhabitants of the settlement? Without these data, how can we meaningfully discuss the various contributions of different social groups to meat consumption? Another question remains concerning meat: how to distinguish traces left by the butcher from those produced by the consumer during preparation and consumption?

While zooarchaeology studies are interested in eating practices, they are most often based on slaughter ages and butcher marks (e.g., [START_REF]Ossements animaux du Moyen-Âge au Monastère de La Charité-sur-Loire[END_REF]). Nevertheless, this approach is incomplete, especially since the author of these traces remains, as previously mentioned, unidentifiable.

The zooarchaeological study of Petra Castellana (11 th -12 th centuries AD) is based on these considerations and on the historical and archaeological studies mentioned above. There is another particularly interesting point: no written source defines the status of Petra Castellana.

The agglomeration below (Castellane) is known as a city, but only later, during the 13 th and 14 th centuries AD. The mention of castrum and castellum only reveals that Petra was a fortified agglomeration. So, was it a city or merely a town? Given that its church was parochial until the middle of the 13 th century AD and considering the size of the site, it is highly plausible it was a city. It seems that during the main settlement of the castrum, Petra was the political (vicinity of the castle), military (the fortifications) and religious (the parish) centre of both agglomerations. However, there is no way of telling which, the castrum or the lowland, held the economic core. The unclear status of the site, combined with the results of the zooarchaeological study, led to the questions presented above. This paper discusses, through different sources and methods, the status of Petra Castellana and its economic bonds with the lowland habitat. Taphonomy has also been a decisive tool in apprehending the consumer as well as the medieval cuisine.

MATERIALS AND METHODS

1.1.

The site Located in the Verdon Valley, Castellane (Alpes de Haute-Provence, Fig. 1) corresponds to the location of the capital of a Gallic population ("Suetrii") and to a chief town in Roman times: Salinae. These two agglomerations are poorly known. In the 11 th century AD, a fortified settlement (Petra Castellana) and a castle (where the Castellane family lived) were built on the heights of the current town. Shortly afterwards, still during the 11 th century AD, the town of Castellane emerged in the lowlands. In 1262, following a siege of the castle and castrum, the Counts of Provence drove out the Castellane family, and the latter's possessions entered the Counts' domains. The castrum started to be abandoned quite early, between the 13 th and 14 th centuries AD in favour of the city below. The beginning of this desertion is potentially linked to the siege and to the resulting destructions. In the Middle Ages, Castellane was an important regional centre. The Lords of Castellane were, from the 10 th to the 13 th centuries AD, among the most important and powerful families in Provence.

Castellane was also an important economic centre in the Alpine area. settlement. Two later settlements left few remains and stratigraphic disruptions have led to their exclusion from analysis. The site was on agricultural land, including terracing, until the 1950s. The excavation revealed residential buildings that originally probably had a residential level, but from which little material was recovered (zone 8). Built manufacturing and trade areas have also been identified. South of the site, but still within the urban zone, there is a silo area (zone 5).

During the archaeological intervention, 2,440 faunal remains (identified and non-identified = NR) were found. Nearly 63% of these finds dated from the 11 th and 12 th centuries AD (1,529 faunal remains). For this occupation, the NISP (Number of Identified Specimens) was 793 (53%). The remains, kitchen waste, were essentially concentrated in the occupation levels (NR = 828 or 54%) and the pit fills (NR = 106 or 7%). Most of the assemblage therefore comes from well-defined archaeological contexts. The fills (diverse) were also rich in remains, with NR = 435 (or 28%). The faunal material was collected by hand, on sight. A multifactorial zooarchaeological study was conducted. It included the identification of the remains at the anatomical and taxonomic level, basic quantifications according to Lyman (1994), the study of animal resources management, butchering analysis and a taphonomic study. To distinguish between goat and sheep, (e.g., [START_REF] Helmer | Discrimination des genres Ovis et Capra à l'aide des prémolaires inférieures 3 et 4 et interprétation des âges d'abattage : l'exemple de Dikili Tash (Grèce)[END_REF][START_REF] Fernandez | Ostéologie comparée des petits ruminants eurasiatiques sauvages et domestiques (genres Rupicapra, ovis, Capra et Capreolus) : diagnose différentielle du squelette appendiculaire[END_REF][START_REF] Zeder | Assessing the reliability of criteria used to identify postcranial bones in sheep, Ovis, and goats, Capra[END_REF] the lower cheek teeth and long bones were used. The age at death was estimated from the degree of bone fusion (e.g., [START_REF] Barone R | Anatomie comparée des mammifères domestiques : fasc. 1-2. Ostéologie, Vigot frères[END_REF][START_REF] Zeder | 6. Reconciling Rates of Long Bone Fusion and Tooth Eruption and Wear in Sheep (Ovis) and Goat (Capra)[END_REF][START_REF] Zeder | A new system for computing long-bone fusion age profiles in Sus scrofa[END_REF] as well as from dental eruption and tooth wear. For Suidae and sheep/goat these estimates were made from observations of the eruption sequence and the degree wear of the upper and lower cheek teeth. The rankings are based on the tables of [START_REF] Matschke | Aging European Wild Hogs by Dentition[END_REF] and [START_REF] Bridault | Wild boar -age at death estimates: the relevance of new modern data for archaeological skeletal material. 1. Presentation on the corpus. Dental and epiphyseal fusion ages[END_REF] for pigs, on those of [START_REF] Greenfield | Absolute age and tooth eruption and wear sequences in sheep and goat: determining age-at-death in zooarchaeology using a modern control sample[END_REF] [START_REF] Binford | Dimensional Analysis of Behaviour and Site Structure: Learning from an Eskimo Hunting Stand[END_REF][START_REF] David | Quantification d'un assemblage osseux: paramètres et tableaux : Actions anthropiques[END_REF]Lyman, 1994). It should be noted that laterality and rank (ribs; vertebrae) are not included in graphic anatomical representations. The same goes for phalanges (anterior, posterior, medial, lateral). Finally, bone survivorship, expressed in %MAU, was applied on the whole bone for the skull, vertebrae and girdles. This explains the difference between the levels of survivorship of these anatomical elements and that of the long bones. Long bone survivorship was documented by dividing each bone into five sections: proximal and distal joints and then proximal, median and distal diaphyses. This type of representation enables the clear visualisation of anomalies. All identified specimens were examined for anthropogenic bone-surface modifications (bone fracturing, e.g., Villa and Mahieu, 1994, and cutmarks, e.g., Audoin-Rouzeau, 1986, Lyman 1994b). Number of marks, anatomical position and orientation were systematically recorded.

Method

Specialised study: animal density and utility indices

Although the lack of data for some bones may bias the results, density and utility indices remain important because they can help explain the under-or over-representation of some elements. Therefore, skeletal bone density indices for sheep/goat, Suidae and cattle [START_REF] Kreutzer | Bison and deer bone mineral densities: Comparisons and implications for the interpretation of archaeological faunas[END_REF][START_REF] Ioannidou | Taphonomy of Animal Bones: Species, Sex, Age and Breed Variability of Sheep, Cattle and Pig Bone Density[END_REF] were compared with %MAU through a correlation test (Spearman's rho). The aim was to determine whether there was a correlation between the mineral density of the anatomical parts and their level of representation in the assemblage.

Table 1 (Appendix) presents the codes used, the density indices and %MAU for the three taxa. Through this method material preservation can be evaluated and differences between the bone sample studied and an expected theoretical assemblage can be compared.

In order to assess hunter-gatherer survival strategies during the Pleistocene, [START_REF] Binford | Dimensional Analysis of Behaviour and Site Structure: Learning from an Eskimo Hunting Stand[END_REF], followed by other specialists [START_REF] Jones | Bare bones archaeology: Bone marrow indices and efficiency[END_REF]Lyman, 1994;[START_REF] Brink | Fat Content in Leg Bones of Bison bison, and Applications to Archaeology[END_REF][START_REF] Rowley-Conwy P | Derivation and Application of a Food Utility Index (FUI) for European Wild Boar ( Sus scrofa L.)[END_REF], developed animal utility indices based on meat (muscle and adipose tissues), bone-fat and marrow content in the different anatomical parts, according to the species. The objective of this method was to identify the preferred use of one and/or the other of these resources and to deduce, for instance, an intensive exploitation which could be attributed to a scarcity of food. This type of study has not been carried out on more recent contexts.

In the current study, the standardized Food Utility Index (sFUI) was used. It combines the different consumable portions mentioned above (Lyman, 1994). This analyse was conducted following the same protocol explained above for the density indices. The density and utility indices for cattle are those established for bison. The same goes for the utility indices of pigs (made for wild boar) and for sheep/goat (made for sheep). These data may, however, be used for taxonomically related species (e.g [START_REF] Rowley-Conwy P | Derivation and Application of a Food Utility Index (FUI) for European Wild Boar ( Sus scrofa L.)[END_REF]. The aim was to evaluate whether adapting this method to recent contexts could be an effective means to address meat consumption strategies. Since the utility indices of the median diaphyses were not available, the lowest value from the proximal and distal diaphyses of the same bone was systematically assigned to it. 1).

RESULTS

Taxonomic distribution and herd composition

The MNIc for cattle is four. Age-at-death estimates indicate the presence of two juveniles and two adults. Pigs are slightly better represented (MNIc = six). Canine morphology suggests the presence of at least one male and one female. No wild boar was identified (based on the absence of reliable criteria of subspecies distinction in the assemblage), nor were individuals within the very young or the older adult categories identified. Five pigs were slaughtered at the optimum fat and meat yield age (one to two years old; Horard-Herbin, 1997) and another at a later stage (between four and eight years old).

For sheep/goat, the MNIc is 22. Twenty-five percent (25%) of these animals were between three and 15 months old (Fig. 4).

Adults (three to eight years old) were the most numerous, representing nearly 70% of individuals. There is a peak around four-year olds and a more pronounced one for five-to eight-year olds. A ratio of 14 sheep to one goat was estimated through the observation of morphological criteria. These frequencies will not be discussed in detail, but several observations need to be highlighted. There is a discrepancy between the frequencies of forelimbs and hindlimbs of cattle. The NISP is close for both (33:25). Yet, the forelimb is observed in full whereas there is a selection of hindlimb elements: femoral and tibial diaphyses (median and distal parts).

Furthermore, coxal elements are overrepresented compared to the ends of the hindlimb long bones, which are completely absent, as is a considerable portion of the tarsals and metatarsals. These data are particularly surprising since the MNE for the coxal bone was obtained from the acetabulum. It is remarkable to observe such a contrast around anatomical connections: well represented vs completely absent portions. Even more striking is that this same pattern can also be observed for the forelimbs and hindlimbs of pigs (except for the humero-radial joint). For sheep/goat, however, there is no obvious under-representation of any particular element or portion of an element. 10 while the proximal humerus (H1), with a similar density, is strongly represented. For sheep/goat and pigs, however, the results suggest that density plays a stronger role in sample composition. For sheep/goat, the cervical (CE1) and thoracic (TH1) vertebrae are poorly represented and have low density. However, this does not reflect natural preservation as some elements are abnormally represented. This is the case for the median diaphysis of the metacarpus (MC2) or the distal diaphysis of the radius (R4). The relatively dense distal metacarpus is under-represented while the less dense radius diaphysis is over-represented. parts of the body of these three taxa, is almost absent. This does not mean, however, that the thorax was not consumed, a point which will be addressed later. It is important to note that some elements with very low meat or fat content are scarcely observed, such as the ends of legs. It should also be noted that several portions with very similar utility indices are observed in various proportions: for cattle, the thorax and the femur are the most nutritious elements (70 to 100% sFUI) but offer a %MAU going from zero to nearly 50. For sheep/goat, the utility index is identical for the coxal and for the different parts of the femur (about 80%) but the %MAU ranges from 15 to more than 60%. Among the best-preserved bone portions, density is generally average and therefore does not seem to be decisive. On the other hand, pigs show a significant correlation (Rs=0.26; p=0.05). However, the statistical result shows a relationship between bone representation and nutritional value and must clearly be considered in the archaeological interpretation, alongside the established utility indices (e.g., higher nutritional value of the thorax over the rest of the body). A closer look at the results

shows that there is a wide variety of representations for the same nutritional values.

Butchering analysis

Blade marks found on both cattle and pigs are scarce and could reflect a certain professional level of skill: The more skilled the butcher is, the less marks he leaves on the bones when he picks up the meat [START_REF] Lignereux | Techniques de boucherie et rejets osseux en Gaule romaine[END_REF]. For sheep/goat (Fig. 8), marks are more frequent, but this can be explained by the NISP which is five times higher. Fractures on fresh bones are numerous. Nevertheless, few are the same for cattle and pigs. It is therefore difficult to establish a carving model for these species.

For each taxa, the skull was also consumed. For goats and pigs, the skull was separated from the rest of the body at the atlas or occipital condyle, where several sharp or blunt blows were made, probably keeping the head down. The horn-cores of goats were recovered and sliced or torn off, maybe for raw material. Finally, the mandibles were separated by tearing at the synchondrosis and cutting them into irregular portions.

The thoracic elements are generally scarce. It seems that three sections were usually extracted from the ribs. The numerous incisions on the ventral surface of the ribs indicate that they were cut at the abdomen. The breaking line was marked with a blade and pressure was applied to break the rib. Sharp blows were rare. Cattle thoracic and lumbar vertebrae were cut longitudinally at each of the transverse apophyses. In small bovids, the cervical vertebrae were cut longitudinally at their centre. Thoracic and lumbar vertebrae were either cut at the centre or at each apophysis, a double incision (double fente, Audoin-Rouzeau, 1986, p. 115). For pig, limited data are available. It seems that the simple incision was preferred.

The legs were mainly sectioned by percussion, whatever the species. The cut is also very similar between taxa. As a result, impact marks were found on the entire skeleton, except for the ends of the legs, which were almost absent. For sheep/goat, as they are better represented, fractures have been observed on the metapods. For each species, all long bones were heavily fractured, releasing small portions, with an average of three to four parts per bone.

13 2. Discussion

Meat quality and demography

Cattle age-at-death is diverse and there is a lack of mature adults, but the low MNI makes interpreting the management of the cattle herd difficult.

Pigs were generally raised for meat and fat but also for skin (as well as cattle and sheep/goat). Castellane is known for its hides, whose techniques are inherited from Grasse, with which it has close economic links since the 11 th century AD [START_REF] Sclafert | Cultures en Haute-Provence : déboisements et pâturages au Moyen Âge[END_REF]. The locality had its own tawery. Petra Castellana's animal products were therefore not limited to food but were a major economic factor. Most of the meat was of average quality (adult sheep) but a few good products were also consumed (three lambs).

The prevalence of sheep/goat over other domestic species is common in Provence [START_REF] Leguilloux | L'archéozoologie et l'interprétation des sites : recherches archéozoologiques sur la Provence romaine et médiévale[END_REF]Rodet-Belarbi, 2011a;b;[START_REF] Dyer | Boucherie médiévale et moderne dans le Val-de-Loire (France) ?[END_REF] and more broadly in the Mediterranean region (e. g. García-García, 2017). Caprine mortality profiles correspond mainly to fleece production (40% from six to ten-year olds) more than to meat consumption [START_REF] Payne | Kill-off Patterns in Sheep and Goats: the Mandibles from Aşvan Kale[END_REF][START_REF] Laurioux | Le village celtique des Arènes à Levroux. L'élevage et les productions animales dans l'économie de la fin du second âge du Fer -Levroux 4[END_REF]. The latter is focused on individuals younger than three years olds, whereas 75% of Petra's sheep/goat remains exceed that age-at-death. The age-at-death profile suggests, rather, wool production on the site or in the vicinity: owners selling non-productive animals downtown to the butcher [START_REF] Forest | Des restes osseux fauniques aux types d'élevage : identification d'innovations[END_REF]. Furthermore, the Provençal butcher could travel long distances to obtain supplies of animals at fairs or from animal farming areas (Stouff, 1970 1 ). This practice, however, was hazardous according to [START_REF] Stouff | Ravitaillement et alimentation en Provence aux XIVe et XVe siècles[END_REF] because once on site, the quantity and/or quality required may not have been available. For him, "l'élevage est inséparable de la boucherie pour tous les macelliers" (Stouff, 1970, p. 153 154). In other words, breeding and butchery are inseparable for all butchers.

Therefore, butchers actively participate in the pastoral economy: they use various breeding contracts known for the Toulouse region and Provence [START_REF] Villa | Les bouchers de Toulouse du XIIe au XVe siècle[END_REF][START_REF] Sclafert | Cultures en Haute-Provence : déboisements et pâturages au Moyen Âge[END_REF]. This multiplicity of butcher activities must be linked to their status. In the city, the wealthiest ones combined activities and delegated their work. They were breeders and could sell skins, tallows, live animals, meat, fish and wool [START_REF] Stouff | Ravitaillement et alimentation en Provence aux XIVe et XVe siècles[END_REF].

Meat processing and culinary practices

Cooking

The systemic absence of some cattle and pig long-bone ends could be explained by a spatial distribution of meat but this hypothesis is hardly conceivable because it is too systematic, and the portions are too precise. The absence of these long-bone ends is more likely linked to a differential treatment of these parts. Consumers were able to put these pieces aside (in a fairly systematic way) for later consumption, in a bone soup for example [START_REF] Binford | Dimensional Analysis of Behaviour and Site Structure: Learning from an Eskimo Hunting Stand[END_REF]. Prolonged cooking, which allows fat to diffuse into the preparation, weakens the bone and can lead to its destruction [START_REF] Costamagno | L'exploitation de la graisse au Paléolithique[END_REF].

This feature has been observed at the charitable institution of the Pas hospital in Rodez in the 14 th century AD [START_REF] Catalo | Déchets de boucherie et alimentation au XlVe siècle à l'hôpital du pas à Rodez (Aveyron)[END_REF]. Here, however, the cuts were larger than in Petra, with four or five pieces per limb compared to usually six or seven in Petra. The chronological shift between the two collections could explain this difference. Indeed, important morphological changes affected culinary ceramics from the 13 th century AD onwards. Small globular pots (the opening diameter of those of Castellane is between nine and 15 cm, or between 3.5 and 5.9 inches) were largely substituted by cooking pots and large open shapes (Lécuyer, 1997). This shift may have favoured larger pieces of meat in later settlements.

Notwithstanding, the different distribution of food seems to be the main factor. In Petra Castellana, the waste comes from family units, while in Rodez, it is from a collective kitchen.

The culinary equipment had to be adapted, with larger shapes. Bone broth is not surprising for a hospital setting as it is a highly nutritious and low-cost food for patients, in this case, women in childbirth, pilgrims and the poor. For Petra, results suggest a variety of culinary practices depending on the anatomical area and the species.

Finally, the MNE of the three taxa varies for each anatomical part, suggesting that a whole animal did not necessarily go to the same person. In rural environments, a "self-sufficient" supply is to be expected, with complete treatment of the animal, whether through fresh meat, cured meats or charcuteries. This practice allows consumers to have meat over a long period. For Petra Castellana, it corroborates the purchase of meat and therefore the proximity of an urban community (in situ or in the lowland).

Density indices

The different results for sheep/goat can be explained by a much higher number of remains or by a distinct anthropic contribution and/or treatment to that of cattle and/or pigs.

Nevertheless, in all cases the results indicate that density itself does not fully explain the composition of the assemblage and that other factors were involved: human action, carnivores and/or physicochemical agents.

Utility indices

Results suggest three types of meat processing:

(1) Some very valuable cuts but among which only a few of the observed parts were intensively exploited, completely destroying them or at least, preventing any taxonomic identification of these elements. The large number of thoracic remains that are taxonomically undetermined support this argument even if taphonomical processes cannot been discarded.

Among the 150 rib remains studied, 95 could not be taxonomically identified (nearly 63%).

For vertebrae, 43 of the 97 remains could not identified to taxon (44%). Because of the fragility of these elements, their nutritional value is certainly underestimated.

(2) Stylopodia, meaty and better represented than ribs but also than zeugopodia, were probably highly consumed but in such a way that they were not destroyed, suggesting a variety of culinary practices.

(3) The weak survivorship of pieces of low nutritional value (mainly autopodia) can be explained by a) a rejection, which appears unlikely since feet are consumed for all three species [START_REF] Stouff | Ravitaillement et alimentation en Provence aux XIVe et XVe siècles[END_REF], b) their consumption and subsequent disposal in an unexplored area of the site, a more probable hypothesis, and/or c) the sale, to the tanners, of autopodia attached to the skin.

Meat consumption

"A beginner uses a knife every month. An average butcher uses a knife every year. I've been using the same knife for nineteen years. It butchered several thousand cattle, without any wear of any kind. Because I only let it pass through where it can pass". Tchouang-Tzeu (370-287 BC;[START_REF] Lignereux | Techniques de boucherie et rejets osseux en Gaule romaine[END_REF].

This quote perfectly summarises the butcher's skill and explains the paucity of cutmarks. For thoracic elements, the double incision (or spine lift) technique seems to have been used in cattle. It consists in extracting the vertebral nucleus by fracturing on either side of the vertebrae [START_REF] Dyer | Boucherie médiévale et moderne dans le Val-de-Loire (France) ?[END_REF]. This is the case in La Charité-sur-Loire until the 14 th century AD [START_REF]Ossements animaux du Moyen-Âge au Monastère de La Charité-sur-Loire[END_REF]). Among small cattle (Fig. 3), several methods seem to coexist: the thoracic and lumbar vertebrae are divided either by a single incision, as at the Hôtel-Dieu de Marseille (Rodet-Belarbi, 2011a), facilitating the extraction of ribs with part of the vertebrae and associated fat, or through a double incision to isolate the core, rich in marrow. There may have been several "butchers" (professional or not) with different techniques. However, it was during the 14 th century AD that butchery began to be standardised [START_REF] Dyer | Boucherie médiévale et moderne dans le Val-de-Loire (France) ?[END_REF]. The single incision becomes an absolute rule for sheep/goat. Before this time, the technique for cutting, including this taxon, is variable and results in a greater variety of pieces and therefore in a wider range of culinary preparations.

The sectioning of long bones into parts of equivalent size is comparable to the findings at the Hôtel du Pas in Rodez and Hôtel-Dieu in Marseille [START_REF] Catalo | Déchets de boucherie et alimentation au XlVe siècle à l'hôpital du pas à Rodez (Aveyron)[END_REF]Rodet-Belarbi, 2011a). During the medieval period, butchers could set their prices without considering the quality of the meat, but only the animal's species, its age and sex. Thus, the butcher often favoured pieces of equal size, faster and easier to extract and well suited for retail [START_REF] Petrowiste | En passant par le mazel. Acheter sa viande au quotidien en France méridionale à la fin du Moyen Âge[END_REF]. These results raise questions about the place of standardised or "generic" meat cuts [START_REF] Petrowiste | En passant par le mazel. Acheter sa viande au quotidien en France méridionale à la fin du Moyen Âge[END_REF] in the medieval diet. It also suggests two distinct phases in cutting, similar to those described by Lyman (1994): the butcher's cut resulting in standardised meat cuts, which corresponds to Lyman's "secondary butchery stage", and the consumption cut, linked to different culinary practices (the "final butchery-consumption stage"). To delve further into these questions, it is necessary to apply the method outlined here (or to develop new ones and apply them) to other assemblages in an attempt to distinguish the marks made by the butcher from those left by the consumer.

Contributions from textual sources

In Antiquity, according to K. [START_REF] Seetah | Multidisciplinary Approach to Romano-British Cattle Butchery[END_REF], the price of a cleaver, its size and the skills required to handle it make it the butcher's tool of choice. These statements probably also apply to the Middle Ages. Indeed, these tools, found in medieval iconography, were adapted to effectively fracture even the densest bone. The use of other objects is therefore difficult to contemplate because they need to be robust, heavy and have a suitable blade to optimise the force. However, hatchets and the carpenter axe (a small axe; handle and blade often about 12 inches or 30 cm) are worth mentioning, as they could have been used and were sometimes mentioned [START_REF] Stouff | Ravitaillement et alimentation en Provence aux XIVe et XVe siècles[END_REF]. These tools, mainly reserved for loggers, charcoal makers and carpenters [START_REF] Burri | Les outils pour acquérir et transformer la matière ligneuse dans les chaînes opératoires techniques des artisanats forestiers en Provence et Haut-Dauphiné au Moyen Âge[END_REF] are close to those found in iconography used to stun and carve cattle and pigs [START_REF] Monteix | Du couteau au boucher : remarques préliminaires sur la préparation et le commerce de la viande à Pompéi[END_REF]. But if these tools look suitable for cutting ribs, they seem inappropriate for chopping thicker bones such as long ones. Thus, the many severed elements identified (97, including 25 long bones) could indicate a professional's work. Slaughtering would have been carried out by people with appropriate anatomical and technical knowledge, as slaughtering and cutting up an animal is difficult. In this sense, the strategic use of a cleaver (or leaf), mainly at the joints, could also be evidence of a professional's work. The many blunt blow and the low presence of cutmark does not invalidate this hypothesis because the cleaver (like the axe) could be used to strike with either the blade or the back of the tool [START_REF] Seetah | Multidisciplinary Approach to Romano-British Cattle Butchery[END_REF][START_REF] Monteix | Du couteau au boucher : remarques préliminaires sur la préparation et le commerce de la viande à Pompéi[END_REF]. In addition, the mallet was part of the butcher's tools (as indicated, for example, in the iconography of Tacuinum Sanitatis2 ).

Although the presence of a butcher is not exceptional, it is essential in order to address the supply systems and economy of the site. On this subject, L. Stouff indicates for Provence that the macelliers3 were present in all cities and in the "vast majority" of Provençal villages (Stouff, 1970, p.114). He adds they were scarcer in hostile regions, especially when crossing the Verdon valley. Indeed, the harsh climatic conditions meant that thousands of animals went down to the Lower Alps at the beginning of winter. To do so, herdsmen crossed Castellane, which had its own salt springs, considered a great asset for agropastoral activities [START_REF] Moriceau | Histoire et géographie de l'élevage français : XVe-XVIIIe siècles[END_REF]. Besides, the locality was key in the regional economy, directly linked to animal products. Textual sources mention the installation of a large fair in Castellane. In the 13 th century AD, it is already considered very old, so during the apogee of the site (11 th -12 th centuries AD) it must have already been in existence. A large proportion of the skins produced on site (see 2.1.) were sold at this fair [START_REF] Sclafert | Cultures en Haute-Provence : déboisements et pâturages au Moyen Âge[END_REF]. The locality was therefore a strategic trading place probably visited by neighbouring populations (especially the highland inhabitants of the Haut Verdon). During the winter, the latter could have obtained supplies from Castellane to cope with the lack of meat until the return of the herds and the travelling butchers.

2.5.

The diet of the common and the mighty folk: the case of medieval Provence

The results from Petra Castellana can be compared with similar contexts as well as elite ones. Firstly, similar contexts consist of Provençal small agglomerations and cities, from the Secondly, this set has been compared with data from neighbouring elite contexts (40-55 km, from the 11 th to the 12 th centuries AD) such as the castles of the Rocca (6) at Niozelles and the Moutte (7) and Notre-Dame (8) at Allemagne-en-Provence [START_REF] Leguilloux | La faune », dans Mottes castrales en Provence : les origines de la fortification privée au Moyen Âge, Paris, Maison des sciences de l'homme, coll[END_REF]2015 ;[START_REF] Unsain | Nouveau regard sur l'alimentation carnée en Provence médiévale : les apports de l'archéozoologie », dans Hommes et caprinés : de la montagne à la steppe, de la chasse à l'élevage Humans and caprines : from mountain to steppe, from hunting to husbandry XXXIXe rencontres internationales d'archéologie et d'histoire d[END_REF].

This comparison revealed two trends. The first one is specific to modest settlements, whether urban, small town or rural. Here, consumption is mainly focused on sheep/goat (sites 1-3-4-5). However, there are exceptions, such as Notre-Dame, where pigs predominate. This could be an adaptation to a forest area favourable to acorns. The zooarchaeological study of Galberto castrum (density, sFUI and classical analyses) is comparable to Petra Castellana's and provides similar results. It suggests a butcher' s cut and sale, as well as a consumer dynamic, rather than production/consumption. This feature is also suggested by the analysis of sites 3-4-5, although this relies on the slaughter patterns only. For Galberto, the proximity of the city of Digne-les-Bains, located 6 km away, indicates a probable supply from the city. Indeed, the latter had a strong commercial position [START_REF] Sclafert | Cultures en Haute-Provence : déboisements et pâturages au Moyen Âge[END_REF]) and a fair, like the one held in Castellane.

The second trend concerns elite occupations in rural areas (very limited data are available for the other elite contexts). Here, a significant proportion of very young pigs and/or goats are observed (three to six months old and ten to 15 months old). The latter would reflect a search for quality meat, in line with the social status of the consumers. The kind of supply is still uncertain. It could have been commercial. In this case, was the network the same as for the rest of the population or was it different? In the city, both possibilities exist. At the Archbishop of Arles and at the Studium of Trets (second half of the 14 th century AD), texts reveal that an agreement had been made with the communal butcher. These contracts ensured them stable prices all year round [START_REF] Stouff | Ravitaillement et alimentation en Provence aux XIVe et XVe siècles[END_REF]. At the same time, H. Noizet has shown that the monks of the abbey of Saint-Martin de Tours, in the 13 th century AD benefited from a structured network where food was transported by land and river [START_REF] Noizet | Le chapitre de Saint-Martin de Tours et la Loire aux IXe-Xe siècles[END_REF][START_REF] Noizet | Le centre canonial de Saint-Martin de Tours et ses domaines périphériques en Val de Loire (IXe-Xe s)[END_REF][START_REF] Noizet | La fabrique de la ville. Espaces et sociétés à Tours (IXe-XIIIe siècle)[END_REF].

The rest of the city had to rely on public (the butcher) and private supplies (Cotté, 2008). For the Provençal castra mentioned above, the lands held by the lords living in the countryside were relatively extensive. In addition, connection to trade routes must have been difficult in these remote areas. A selection from the production of tenant farmers is therefore a more likely hypothesis. It could have consisted of taxes [START_REF] Carrier | Paysans des Alpes : les communautés montagnardes au Moyen Âge[END_REF], purchases from stockbreeders, or the lords' own produce since farmers are in charge of the herds [START_REF] Heers | Esclaves et domestiques au Moyen Age dans le monde méditerranéen[END_REF].

The results from Petra Castellana not only contribute to characterise the supply systems of Provençal cities, but also enable a discussion of the supply systems specific to the countryside. It is thus possible to perceive nuances and contrasts between the different components of medieval Provençal society.

Conclusions

The results on meat consumption in Petra Castellana are abundant and promising.

Although they correspond to the main model identified for Provence (preferential consumption of sheep/goat), they also provide information on the supply system at the site, its surroundings and, more broadly, Provence. Culinary practices have also been discussed.

Though it seems that the carving of all three species did not consider the quality of the different meat cuts (by favouring a standardised cut), the cook adapted his or her preparations to the types of meat available (absence of joints, intense consumption of the thorax and differential processing for the different limb sections). In addition, the cutting techniques (material and skills) and textual sources relating to the site suggest that it was a professional job.

It is currently not possible to determine the economic status of the two settlements from the 11 th and the 12 th centuries AD. There could have been an economic space in both Petra Castellana and Castellane, or one of the two supplied both itself and the other. However,

given the close distance between the two, it is possible to consider them as two districts of the same city.

As the data focus mainly on small areas of the site, it is necessary to extend the excavation to other areas. [START_REF] Binford | Dimensional Analysis of Behaviour and Site Structure: Learning from an Eskimo Hunting Stand[END_REF]Lyman, 1994;[START_REF] Ioannidou | Taphonomy of Animal Bones: Species, Sex, Age and Breed Variability of Sheep, Cattle and Pig Bone Density[END_REF]

  Located at the convergence of several axes leading into the Alps, it dominated one of the few convenient crossing points of the Verdon river. The presence of gypsum in local geological formations leads to the rising of salt springs. These were exploited in ancient times and explain the name of the city during Roman times. This salt, combined with the roads, made Castellane an important point for transhumance. The relatively opulent medieval Castellane was represented by three main sites (fig 2): (1) the Roc, on which the fortress was erected until its destruction at the end of the 15 th century, (2) Castellane, where the current town is located, mentioned in the 11 th century and fortified in 121 the middle of the 14 th century AD, and (3) 122 Petra Castellana, the focus area of this study. 123 The castrum dominated the Verdon valley by 124 its position and the city was easily accessible 125 to its inhabitants (at about 300 metres). 126 127 This settlement of about two ha (fig. 3) has been the target of planned excavation campaigns since 2016 (Buccio et al., 2018). It has a still partially standing enclosure and a parish church (adjacent to zone 12). Several surveys across the site have aimed at studying both buildings and open spaces. These surveys represent about 2% of the surface area of the settlement. At the end of three excavation campaigns, the first documented medieval occupation was attributed to the 11 th and 12 th centuries AD. Most of the faunal material is associated with this

Figure 1 :

 1 Figure 1 : geographical location of Castellane (map from geoportail.gouv.fr) (B&W)

Figure 3 :

 3 Figure 3 : Plan of Petra Castellana and location of the excavation areas (Buccio) (colour)

Figure 4 :

 4 Figure 4: Slaughtering ages for sheep/goat expressed in MNIc (the curve stands for the %MNIc) (B&W)

  281 1.3.2. Utility indicesSpearman's rho does not show any correlation (Fig.7) for cattle (Rs=-0.04; p=0.77) and sheep/goat (Rs=0.080; p=0.61). This suggests that the %MAU of anatomical portions is not correlated to their nutritional content. For example, the thorax, one of the most nutritious

Figure 6 :

 6 Figure 6: Comparison of cattle, pigs and sheep/goat skeletal parts (%MAU) and mineral density indices. See appendix for codes used (B&W)

Figure 7 :

 7 Figure 7: Comparison of cattle, pigs and sheep/goat skeletal parts (%MAU) and standardised Food Utility Indices (sFUI). See appendix for codes used (B&W)

Fig. 8 :

 8 Fig. 8: Location of anthropic traces on sheep/goat. Font from Archeozoo.org/ Michel Coutureau (INRAP 2013)) (Colour)

  11 th to the 14 th centuries AD: (1) Galberto castrum, located at Digne-les-Bains, about 35 km from Castellane (Unsain unpublished); (2) Notre-Dame castrum 4 (rural part, Allemagne-en-Provence, about 40 km, Unsain 2019); (3) Marseille (city, Rodet-Belarbi, 2011a); (4-5) Marignane (town) and Fos-sur-Mer (castrum near Marseille, Rodet-Belarbi, 2011b ; 2011c).

Table 1 :

 1 Further work could help determine if these are isolated results, reflecting either a bias in the composition of the assemblage, a specific private consumption or a recurrent model. For now, these data suggest the presence of a butcher in the vicinity of Petra Castellana rather than a travelling butcher. This zooarchaeological study, carried out using an updated protocol (e.g., density and utility indices) as opposed to previous French medievalist approaches, has altered the models of livestock rearing and consumption proposed by historians and zooarchaeologists to date. Furthermore, the method for discussing the butcher/consumer distinction needs to be further developed. Indeed, since the consumer's perspective is not easily palpable to historians, this would encourage new debates. Quantifiaction of NISP, MNE and MNIc for sheep/goat, cattle and pig

	582	Appendix:
		SHEEP/GOAT			CATTLE				PIG
		ANATOMICAL PART	NIS P	MN E	MNI c	ANATOMICAL PART	NIS P	MN E	MNI c	ANATOMICAL PART	NIS P	MN E	MNIc
		Horn-cores	6	4	3	Horn-cores	2	1	1	Skull	8	2
		Skull	17	3	3	Skull	12	3	3	Mandible	24	7
		Mandible	29	11	6	Mandible	5	2	1	Atlas	1	1
		Hyoid	1	1	1	Hyoid	0	0	0	Axis	0	0
		Atlas	5	3	3	Atlas	1	1	1	Cervical vertebrae	4	3
		Axis	5	2	2	Axis	0	0	0	Thoracic vertebrae	3	3
		Cervical vertebrae	6	1	1	Cervical vertebrae	1	1	1	Rib	14	10
		Thoracic vertebrae	8	5	1	Thoracic vertebrae	5	2	1	Scapula	4	4
		Lumbar vertebrae	7	3	1	Lumbar vertebrae	2	1	1	Humerus PJ	0	0
		Sacral vertebrae	1	1	1	Sacral vertebrae	0	0	0	Humerus PD	1	1
		Rib	17	15	1	Rib	24	4	1	Humerus MP	4	4
		Scapula	20	12	8	Scapula	4	2	2	Humerus DD	7	5
		Humerus PJ	3	2	2	Humerus PJ	4	4	1	Humerus DJ	7	6
		Humerus PD	3	3	1	Humerus PD	4	3	2	Radius PJ	5	5
		Humerus MP	10	7	3	Humerus MP	2	2	1	Radius PD	5	5
		Humerus DD	11	10	5	Humerus DD	3	3	2	Radius MD	2	2
		Humerus DJ	13	13	7	Humerus DJ	1	1	1	Radius DD	1	1
		Radius PJ	10	10	5	Radius PJ	1	1	1	Radius DJ	0	0
		Radius PD	18	14	10	Radius PD	3	3	2	Ulna PJ	0	0
		Radius MD	18	13	4	Radius MD	2	2	1	Ulna PD	2	2
		Radius DD	17	16	6	Radius DD	1	1	1	Ulna DD	0	0
		Radius DJ	3	2	3	Radius DJ	2	2	1	Carpal	0	0
		Ulna PJ	5	5	5	Ulna PJ	0	0	0	Metacarpal III PJ	0	0
		Ulna PD	7	7	2	Ulna PD	0	0	0	Metacarpal III MD	0	0
		Ulna DD	5	5	1	Ulna DD	1	1	1	Metacarpal III DJ	0	0
		Carpal	4	4	1	Carpal	3	1	1	Metacarpal IV PJ	0	0
		Metacarpal PJ	6	6	4	Metacarpal PJ	1	1	1	Metacarpal IV MD	0	0
		Metacarpal MD	3	2	1	Metacarpal MD	1	1	1	Metacarpal IV DJ	0	0
		Metacarpal DJ	4	4	3	Metacarpal DJ	1	1	1	Sacrum	0	0
		Sacrum	2	1	1	Sacrum	2	1	1	Coxal	5	3
		Coxal	10	10	6	Coxal	11	5	3	Femur PJ	0	0
		Femur PJ	5	5	2	Femur PJ	0	0	0	Femur PD	2	1
		Femur PD	7	5	4	Femur PD	0	0	0	Femur MD	2	1
		Femur MD	9	7	3	Femur MD	3	2	2	Femur DD	2	2
		Femur DD	11	11	8	Femur DD	3	3	3	Femur DJ	0	0
		Femur DJ	2	2	1	Femur DJ	0	0	0	Patella	0	0
		Patella	3	3	2	Patella	0	0	0	Tibia PJ	0	0
		Tibia PJ	2	2	1	Tibia PJ	0	0	0	Tibia PD	6	5
		Tibia PD	29	10	5	Tibia PD	2	2	2	Tibia MD	5	5
		Tibia MD	13	11	6	Tibia MD	3	2	2	Tibia DD	2	2
		Tibia DD	13	11	5	Tibia DD	3	2	2	Tibia DJ	0	0
		Tibia DJ	3	2	4	Tibia DJ	0	0	0	Calcaneum	2	2
		Malleolus	1	1	1	Malleolus	0	0	0	Talus	1	1
		Calcaneum	5	3	2	Calcaneum	1	1	1	Metatarsal III PJ	1	1
		Talus	8	6	5	Talus	0	0	0	Metatarsal III MD	1	1
		Tarse	4	3	3	Tarse	0	0	0	Metatarsal III DJ	1	1
		Metatarsal PJ	11	5	4	Metatarsal PJ	0	0	0	Metatarsal IV PJ	0	0
		Metatarsal MD	7	5	3	Metatarsal MD	0	0	0	Metatarsal IV MD	0	0
		Metatarsal DJ	7	7	3	Metatarsal DJ	0	0	0	Metatarsal IV DJ	0	0
		Phalanx 1	12	8	1	Phalanx 1	2	2	1	Phalanx 1	2	1
		Phalanx 2	2	2	1	Phalanx 2	1	1	1	Phalanx 2	5	4
		Phalanx 3	3	3	1	Phalanx 3	1	1	1	Phalanx 3	2	2

Table 2 :

 2 %MAU, density indices, sFUI (standardized Food Utility Index) and codes for skeletal parts of Sheep/goat (Ovis aries & Capra hircus), Bos taurus and Sus scrofa. Bones that are both missing in the assemblage and without any indices are not presented.

PJ: proximal joint; PD: proximal diaphysis; MD: medial diaphysis; DD: distal diaphysis; DJ: distal joint. Indices from

His work is relevant because, even if it focuses mainly on the 14 th century AD, the meat preferences described are very close to zooarchaeological data from earlier periods.

Ibn Butlan, ca 1440. Tacuinum Sanitatis, illuminated manuscript, Germany, BNF, Manuscrit latin 9333, fol. 71 v

The term "butcher" appeared at the end of the 14 th century AD and is associated with inferior quality meat cuts[START_REF] Villa | Les bouchers de Toulouse du XIIe au XVe siècle[END_REF]

This settlement is divided into two parts: the castle and the "peasant settlement", located below.

Acknowledgments:

First of all, we would like to warmly thank the anonymous reviewers for their involvement, advice and kindness.

The project PATHWAy leading to this publication has received funding from Excellence Initiative of Aix-Marseille University -A*MIDEX, a French « Investissements d'Avenir » programme.

The first author would like to thank in particular Aix Marseille University, which funds this research through a doctoral contract. She also wants to thank the Departmental Archaeology Service of Alpes-de-Haute-Provence (04), first directed by Mathias Dupuis and then by Vincent Buccio, for their trust in letting her conduct the zooarchaeological study.

We would like to express our gratitude to Jean-Philip Brugal (LAMPEA, UMR 7269) for the collection of comparative anatomy he has made available.

We also thank Dr Karina Gerdau for reviewing the manuscript, as well as Isabelle Rodet-Belarbi and Lionel Gourichon (CEPAM, UMR 7264) for their valuable advice.


Idrissi O El
email: el-idrissi_o@univ-corse.fr

Seasonal change in trace element concentrations of Paracentrotus lividus: its use as a bioindicator

Keywords: Trace elements, Paracentrotus lividus, Bioindicator, Seasonal variation

Importance physiological factors have been identified -Gonadosomatic index is the variable most closely related to temporal variations -Trace elements contamination is lower during the summer season -The use of gonads should be avoided during the spawning period (autumn/winter)

Introduction

The growth of industrial, agricultural and urban activities gives rise to the introduction of considerable amounts of chemicals in marine coastal ecosystems. These substances have toxic properties likely to cause extensive damage at the scale of organisms, populations and ecosystems [START_REF] Nordberg | Handbook on the Toxicology of Metals[END_REF][START_REF] Amiard | Les risques chimiques environnementaux : méthodes d'évaluation et impacts sur les organismes[END_REF]. Furthermore, intensive human activities, particularly in coastal areas, have a major environmental impact on these productive zones [START_REF] Papathanassiou | State and pressures of the marine and coastal Mediterranean environment[END_REF]. The United Nations Environment Programme estimated that 650 million tons of sewage, 129,000 tons of mineral oil, 60,000 tons of mercury, 3,800 tons of lead and 36,000 tons of phosphates are dumped into the Mediterranean each year. In addition, 70 per cent of the wastewater dumped into the Mediterranean is untreated. These pressures make the Mediterranean a vulnerable ecological unit [START_REF] Turley | The changing Mediterranean Sea -A sensitive ecosystem?[END_REF]. Furthermore, as the water bodies renews with a few decades in the Mediterranean versus a few centuries for the ocean, this sea is a veritable laboratory for observing the pressures and changes that humans exert on the environment [START_REF] Bethoux | The Mediterranean Sea: A miniature ocean for climatic and environmental studies and a key for the climatic functioning of the North Atlantic[END_REF].

Trace elements (TEs) are among the most common contaminants in the marine ecosystem. Due to their toxicity, persistence and ability to accumulate in marine organisms, they are considered as serious pollutants in marine ecosystems [START_REF] Bonanno | Trace element compartmentation in the seagrass Posidonia oceanica and biomonitoring applications[END_REF]. TEs are present in the different compartments of the environment at low concentrations [START_REF] Baize | Éléments traces dans les sols. Fonds géochimiques, fonds pédogéochimiques naturels et teneurs agricoles habituelles : définitions et utilités[END_REF]. In the marine environment, they can remain in solution, be adsorbed on sedimentary particles, precipitate to the bottom, or be bioaccumulated or biomagnified by organisms and to reach concentrations that can be toxic [START_REF] Warnau | Distribution of heavy metals in the echinoid Paracentrotus lividus from the Mediterranean Posidonia oceanica ecosystem: seasonal and geographical variations[END_REF]. Above a certain threshold, all TEs present a potential danger that can cause disturbances at cellular level, individual level, and also population or ecosystem levels [START_REF] Amiard | Les risques chimiques environnementaux : méthodes d'évaluation et impacts sur les organismes[END_REF]. They represent a potential danger for marine organisms (e.g. [START_REF] Allemand | Alteration of calcium transport as a mechanism of cell injury induced by HgCl2 in sea urchin eggs[END_REF][START_REF] Walter | Mediating effect of calcium in HgCl2 cytotoxicity in sea urchin eggs: role of mitochondria in Ca 2+ -mediated cell death[END_REF] and for human consumers of sea urchin gonads. As a result of the threats posed by TEs in the environment, they must be continuously monitored from their emission sources to their final deposition in the oceans [START_REF] Richir | A reassessment of the use of Posidonia oceanica and Mytilus galloprovincialis to biomonitor the coastal pollution of trace elements: New tools and tips[END_REF].

In order to assess the levels of contaminants available in the ecosystem, organisms can be used as bioindicators. Postmetamorphic echinoids in general, and Paracentrotus lividus (Lamarck, 1816), in particular, are interesting candidates for the bioindication of TEs contaminations and have already been used in the Mediterranean and elsewhere (e.g. [START_REF] Augier | Teneurs en métaux lourds des oursins comestibles Paracentrotus lividus (Lamarck) prélevés dans quatre secteurs tests du littoral de Marseille (Méditerranée, France)[END_REF][START_REF] Guendouzi | Seasonal variation in bioavailability of trace metals in the echinoid Paracentrotus lividus (Lamarck, 1816) from Algerian coastal waters: effect of physiological indices[END_REF][START_REF] Ternengo | Spatial variations in trace element concentrations of the sea urchin, Paracentrotus lividus, a first reference study in the Mediterranean Sea[END_REF]. Due to its wide distribution, abundance in several coastal ecosystems, ease of harvesting, longevity, relative sedentarity and high tolerance of pollutants, Paracentrotus lividus is an organism that is recognized for its role as bioindicator [START_REF] Warnau | Distribution of heavy metals in the echinoid Paracentrotus lividus from the Mediterranean Posidonia oceanica ecosystem: seasonal and geographical variations[END_REF][START_REF] Geraci | Nickel, lead, and cadmium induce differential cellular responses in sea urchin embryos by activating the synthesis of different HSP70s[END_REF][START_REF] Salvo | Statistical characterisation of heavy metal contents in Paracentrotus lividus from Mediterranean Sea[END_REF]. Its gonads and digestive tract are described as the organs accumulating the most trace elements [START_REF] Augier | Teneurs en métaux lourds des oursins comestibles Paracentrotus lividus (Lamarck) prélevés dans quatre secteurs tests du littoral de Marseille (Méditerranée, France)[END_REF], thus, the study of their ecotoxicological properties is also of public health interest [START_REF] Salvo | Toxic and essential metals determination in commercial seafood: Paracentrotus lividus by ICP-MS[END_REF]. Trace elements concentration in the gonads is known to vary according to different biological (age, gender), physiological (reproduction) or environmental (season) factors [START_REF] Warnau | Distribution of heavy metals in the echinoid Paracentrotus lividus from the Mediterranean Posidonia oceanica ecosystem: seasonal and geographical variations[END_REF][START_REF] Guendouzi | Seasonal variation in bioavailability of trace metals in the echinoid Paracentrotus lividus (Lamarck, 1816) from Algerian coastal waters: effect of physiological indices[END_REF][START_REF] Rocha | Seasonal effect in nutritional quality and safety of the wild sea urchin Paracentrotus lividus harvested in the European Atlantic shores[END_REF].

The elementary constitution of the sea urchin reflects the composition of its environment and provides a basis for monitoring the patterns of change of contamination [START_REF] Morrison | Talitrus saltator as a biomonitor: An assessment of trace element contamination on an urban coastline gradient[END_REF].

In the Mediterranean, numerous studies using Paracentrotus lividus as a bioindicator have studied classical TEs such as zinc or lead, but there has been little or no description of the contamination related to emerging trace elements (e.g. [START_REF] Rouane-Hacene | Seasonal assessment of biological indices, bioaccumulation, and bioavailability of heavy metals in sea urchins Paracentrotus lividus from Algerian west coast, applied to environmental monitoring[END_REF][START_REF] Guendouzi | Seasonal variation in bioavailability of trace metals in the echinoid Paracentrotus lividus (Lamarck, 1816) from Algerian coastal waters: effect of physiological indices[END_REF]. Wellknown throughout the Mediterranean region, Paracentrotus lividus is a species of economic and ecological importance [START_REF] Lawrence | Effects of feeding on the environment: Echinoidea[END_REF][START_REF] Kelly | Sea urchin aquaculture: a review and outlook[END_REF]. The sea urchin is of high commercial value and represents a complementary resource for artisanal fishing. The taste quality of its gonads also makes it a species appreciated and targeted by recreational fishing. In addition, as a primary consumer, it plays a key role in the structuring and functioning of benthic ecosystems and more particularly of macrophyte communities [START_REF] Lawrence | Effects of feeding on the environment: Echinoidea[END_REF]. anthropic pressure [START_REF] Lafabrie | Metal contamination of Posidonia oceanica meadows along the Corsican coastline (Mediterranean)[END_REF][START_REF] Gobert | Trace element concentrations in the apex predator swordfish (Xiphias gladius) from a Mediterranean fishery and risk assessment for consumers[END_REF][START_REF] Marengo | Comparison of elemental composition in two wild and cultured marine fish and potential risks to human health[END_REF]. Nevertheless, according to recent studies, local contamination similar to that recorded in other anthropized areas in the Mediterranean can be found [START_REF] Richir | Bioassessment of trace element contamination of Mediterranean coastal waters using the seagrass Posidonia oceanica[END_REF], with areas classified on the basis of different levels of contamination as anthropized or preserved sites [START_REF] Ternengo | Spatial variations in trace element concentrations of the sea urchin, Paracentrotus lividus, a first reference study in the Mediterranean Sea[END_REF]. This is a real asset that makes it a particularly suitable study area to identify contaminants and to monitor their dynamics according to anthropogenic pressures.

The purpose of this study is (i) to monitor the spatio-temporal dynamics of 22 TEs (classical and emerging) in sea urchin gonads collected along the Corsican coasts, and (ii) to evaluate the seasonal patterns of change in the pollution index characterizing each site to determine whether these variations are linked to the sea urchin's physiology or to contamination. This paper will assess the bio-indicator potential of sea urchins and compare this model with other bioindicators.

Material and Methods

Sampling sites, collection and preparation of samples

Sea urchin samples were collected in May, August and November 2017, and in order to have a complete range of seasonal monitoring, the February 2017 data of [START_REF] Ternengo | Spatial variations in trace element concentrations of the sea urchin, Paracentrotus lividus, a first reference study in the Mediterranean Sea[END_REF] were added. Sea urchins were collected in the Western Mediterranean Sea in four Corsican coastal areas between 1 and 5 m depth (Figure 1). In each area, two sites were defined, diverging by their ecological characteristics and their degree of anthropization: (1) a reference site, chosen for its distance from any pollution source and supposed to have a good ecological status, and (2) a site close to identified anthropogenic sources (wastewater treatment plant, commercial harbour, marina and a former asbestos mine) supposedly impacted.

Thirty sea urchins were collected in each area, 15 per site for each season, resulting in a total of 480 individuals harvested in this study. After measuring height and weight, the sea urchins were dissected and the gender was determined. The sex ratio has been respected, to the extent possible, to avoid bias. The gonads were removed and weighed to calculate the gonadosomatic index of each individual. This index was calculated using the following formula: (GFW/ TFW) *100 where GFW is the gonad fresh weight and TFW is total fresh weight. Gonads were cleaned with ultrapure water and stored at -20°C.

Trace element analysis

Prior to the analysis, samples were lyophilized (CHRIST LCG Lyochamber Guard 121550 PMMA/Alpha 1-4 LD plus) and ground in an agate mortar. Approximately 0.2 g of each dried material was mineralized in a closed microwave digestion labstation (Ethos D Milestone Inc.), using nitric acid and hydrogen peroxide as reagents (suprapur grade, Merck). The TE concentrations were determined by Inductively Coupled Plasma Mass Spectrometry using Dynamic Reaction Cell technology (ICP-MS ELAN DRC II, Perkin Elmer), according to the method described by [START_REF] Richir | A reassessment of the use of Posidonia oceanica and Mytilus galloprovincialis to biomonitor the coastal pollution of trace elements: New tools and tips[END_REF]. A total of 22 trace elements were analyzed: silver (Ag), aluminium (Al), arsenic (As), barium (Ba), beryllium (Be), bismuth (Bi), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), lithium (Li), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), antimony (Sb), selenium (Se), tin (Sn), uranium (U), vanadium (V), and zinc (Zn). In order to check the purity of the chemicals used, a large number of chemical blanks were run every 40 samples. Analytical quality control was achieved using Certified Reference Materials (CRM), DORM-4 (fish protein), NIST 1566b (oyster) and NIST 2976 (mussel tissue). For each TE, detection limit (LD) and quantification limit (LQ) were calculated according to [START_REF] Currie | Nomenclature in evaluation of analytical methods including detection and quantification capabilities: (IUPAC recommendations 1995)[END_REF] and [START_REF] Grinzaid | Terms and methods of estimating detection limits in various analytical methods[END_REF] depending on their specific blank distribution. The results are expressed in milligrams of element per kilogram of dry weight ± standard error (mg.kg - 1 dw ± se). TEs with values generally below the detection limit were removed from the database.

For the others, concentrations below the LD were replaced with a value of LD/2, as reported by [START_REF] Skrbić | Principal component analysis of indicator PCB profiles in breast milk from Poland[END_REF].

Data analysis

The data was log-transformed in order to meet the conditions of application of the parametric tests, to reduce the effect of outliers skewing the data distribution, and to bring elemental concentrations within the same range [START_REF] Gobert | Trace element concentrations in the apex predator swordfish (Xiphias gladius) from a Mediterranean fishery and risk assessment for consumers[END_REF]. Analyses were performed using XLSTAT software [START_REF] Addinsoft | XLSTAT statistical and data analysis solution[END_REF]. A multivariate analysis of variance (MANOVA) was applied to explore the influence of gender (2 levels), site (8 levels) and season (4 levels) factors to the observed differences in TE concentration. MANOVA was then followed by posteriori univariate ANOVA and post-hoc Tukey's honestly significant difference (HSD) tests. Pearson rank correlation tests were performed to investigate the relationship between the trace element levels (inter-element correlations) and the biological data (weight, size and gonadosomatic index). To determine the significance and strength of each relationship, the correlation coefficient was calculated together with p-values. A significant difference is considered as a p-value less than 0.05. was calculated for each site. Developed by [START_REF] Richir | A reassessment of the use of Posidonia oceanica and Mytilus galloprovincialis to biomonitor the coastal pollution of trace elements: New tools and tips[END_REF], the TEPI is a modified version of the Metal Pollution Index [START_REF] Usero | Trace metals in the bivalve mollusc Chamelea gallina from the Atlantic coast of southern Spain[END_REF]. It has the advantage of taking into account nonmetallic TEs to study As and Se. Moreover, unlike the Metal Pollution Index, the TEPI allows a reliable comparison of study sites, regardless of TEs or the biological model used [START_REF] Richir | A reassessment of the use of Posidonia oceanica and Mytilus galloprovincialis to biomonitor the coastal pollution of trace elements: New tools and tips[END_REF]. As recommended for the calculation of the TEPI, the data were standardized by mean normalization [START_REF] Richir | A reassessment of the use of Posidonia oceanica and Mytilus galloprovincialis to biomonitor the coastal pollution of trace elements: New tools and tips[END_REF]. TEPI values were calculated using the following formula: TEPI= (Cf1 Cf2…Cfn) 1/n where Cfn is the mean normalized concentration of the TE at each site or station and n is the number of TE examined. The higher the TEPI value, the more contaminated the site is. A 3-level water quality scale was established, using the method developed by [START_REF] Richir | Bioassessment of trace element contamination of Mediterranean coastal waters using the seagrass Posidonia oceanica[END_REF]. The first level corresponds to the Low Contamination Level (LCL), the second level to a Medium Contamination Level (MCL) and the third level to a High Contamination Level (HCL).

Results

Biotic factors of the sea urchin

The gonadosomatic index ranged from 0.72 to 6.7 and shows different patterns according to the site considered (Figure 2). Among the 20 TEs measured, the concentration of 16 TEs is found negatively correlated with gonadosomatic indices (Ag, Al, As, Ba, Cd, Co, Cr, Fe, Mn, Mo, Ni, Pb, Sb, Se, U, V) (p-value < 0.05) and only one TE (Zn) is positively correlated with the gonadosomatic indices (r = 0.011, p = 0.020).

There are significant positive correlations for 14 out of 20 TEs with both the weight and the size of sea urchins. The larger the individuals, the more they tend to accumulate TEs (Ag, As, Cd, Co, Cr, Fe, Li, Mo, Ni, Pb, Sb, Se, U, V) in the gonads (p-value < 0.05).

Trace element concentrations

The mean TE concentrations measured in the gonads of Paracentrotus lividus, at each site for all seasons, are presented in Figure 2. Be and Bi observed concentrations are below the detection limit, so they have not been taken into account in the statistical analyses. Zn is the most abundant TE (175.454 ± 12.004 mg.kg -1 ) while the lowest abundance is observed for Sn (0.016 ± 0.001 mg.kg -1 ).

TE concentrations follow the sequence: Zn

> Fe > As > Al > V > Cu > Se > Ni > Mn > Cr > U > Co > Mo > Cd > Ba > Li > Ag > Pb > Sb > Sn.
There are 14 significant negative correlations (Ag -Sn, As -Cu, As -Sn, Cd -Cu, Cd -Sn, Zn -Cr, Zn -Fe, Zn -Mo, Zn -Ni, Zn -Pb, Zn -U, Zn -V). The highest positive inter-elemental relationships are U-V (r = 0.83), Co-Cr (r = 0.78), V -Cr (r = 0.71), Ni-Cr (r = 0.67) and U-Cr (r = 0.63) with p-value < 0.001.

The MANOVA results showed significant differences (p-value ˂ 0.001) in TE concentrations between the genders, the seasons and the sites.

Temporal variations of trace elements

The concentration of all TEs except Ag significantly vary among seasons variations (p-value < 0.0001) (Table 1). Noteworthy, TE display similar fluctuation profiles that is a decrease during the spring and summer seasons. The result of TEPI (Figure 3) is in accordance with such results, evidencing that sea urchins have higher TE concentration during the legal harvesting season (i.e. autumn and winter). Over the 8 values that are in HCL, 6 are in winter and concern four site of three areas (i.e. Saint-Florent 1, Saint-Florent 2, Ajaccio 2, Calvi 1). The TE content is higher when gonadosomatic indices are low in autumn and winter. Most TEs are probably stored in the gonads and are not expelled with the gametes.

Spatial variations of trace elements

The TE concentrations vary considerably depending on the sampling stations (Table 2). Zn is the only element that does not significantly vary spatially (p-value = 0.543). The annual TEPI reveals two stations with High Contamination Level: Saint-Florent 1 (TEPI = 1.127) and Saint-Florent 2 (TEPI = 1.222). Conversely, Bonifacio 2 (TEPI = 0.726) and Calvi 2 (TEPI = 0.738) have been classified as Low Contamination Level.

Variations of trace elements according to gender

The concentration of 11 out of the 20 TE are different between male and female (p-value < 0.05), the average concentrations of Fe, Cr, Mo, Ni, Pb, U and V being higher in male, although those of As, Cd, Se and Zn are higher in female (Table 3). Specifically, Zn and Fe are the two TEs presenting the highest differences among gender, Zn being 5 times more concentrated in female and Fe 1.75 times more concentrated in males (p-value < 0.0001). The differences observed don't vary with the seasons and very little according to the sites.

Discussion

Measurements of 22 TEs were conducted in 480 sea urchins. Paracentrotus lividus has a greater tendency to accumulate essential TEs such as Cu, Fe, Mn or Zn in contrast to non-essential TEs (e.g. [START_REF] Storelli | Heavy metals in the aquatic environment of the Southern Adriatic Sea, Italy: macroalgae, sediments and benthic species[END_REF][START_REF] Guendouzi | Seasonal variation in bioavailability of trace metals in the echinoid Paracentrotus lividus (Lamarck, 1816) from Algerian coastal waters: effect of physiological indices[END_REF]. The difference of TE concentration in sea urchin gonads between the two genders has been little explored (e.g. [START_REF] Bayed | The Paracentrotus lividus populations from the northern Moroccan Atlantic coast: growth, reproduction and health condition[END_REF][START_REF] Soualili | Assessment of seawater pollution by heavy metals in the neighbourhood of Algiers: use of the sea urchin, Paracentrotus lividus, as a bioindicator[END_REF]. Zn is an essential element in gametogenesis [START_REF] Unuma | Zinc-binding property of the major yolk protein in the sea urchin -implications of its role as a zinc transporter for gametogenesis[END_REF], which explains the high content found in the gonads [START_REF] Unuma | Zinc-binding property of the major yolk protein in the sea urchin -implications of its role as a zinc transporter for gametogenesis[END_REF]. Ovogenesis requires greater amounts of Zn than spermatogenesis, which is why concentrations are higher in females than in males. According to [START_REF] Unuma | Zinc-binding property of the major yolk protein in the sea urchin -implications of its role as a zinc transporter for gametogenesis[END_REF], the Major Yolk Protein (MYP) transports the assimilated Zn from the digestive tract to the gonads.

Although non-essential TE are expected to have no physiological role, we have evidence however, differential accumulation of those non-essential TE between male and female. They probably have a strong affinity with certain essential TEs and are thus bioaccumulated with them. When there are several TEs in an environment, antagonistic or synergistic effects can indeed occur (Kabata-Pendias and Pendias, 2001). Moreover, positive inter-elemental relationships have been observed: Cr-V; Cr-Ni; Cr-U are among the strongest combinations. Ni, U and V could be bioaccumulated with Cr, an essential element, in male gonads. A high level of some non-essential TEs can reduce sperm fertility or increase the frequency of embryo malformations that can lead to death [START_REF] Pagano | The sea urchin: bioassay for the assessment of damage from environmental contaminants[END_REF][START_REF] Soualili | Assessment of seawater pollution by heavy metals in the neighbourhood of Algiers: use of the sea urchin, Paracentrotus lividus, as a bioindicator[END_REF].

The population in Corsica increases considerably during summer with intense maritime and recreational activities (INSEE, 2018). It's therefore surprising that the contamination levels are lowest this season. Furthermore, studies indicate that transfers inside the echinoid occur on a relatively short time scale (typically of the order of a week) (e.g. [START_REF] Miramand | Comparative study of vanadium biokinetics in three species of echinoderms[END_REF][START_REF] Warnau | Biokinetics of selected heavy metals and radionuclides in the common Mediterranean echinoid Paracentrotus lividus: sea water and food exposures[END_REF]; These low concentrations of trace element in summer cannot be due to delays in gonad contamination. An increase in the gonad weight of Paracentrotus lividus is correlated with a decrease in TE concentrations, and inversely. There are two main cell populations in the germinal epithelium of the sea urchin gonad: germinal cells and somatic cells called nutritive phagocytes [START_REF] Holland | Annual cycles in germinal and non-germinal cell populations in the gonads of the sea urchin Psammechinus microtuberculatus[END_REF][START_REF] Byrne | Annual reproductive cycles of the commercial sea urchin Paracentrotus lividus from an exposed intertidal and a sheltered habitat on the west coast of Ireland[END_REF][START_REF] Walker | Nutritive phagocyte incubation chambers provide a structural and nutritive microenvironment for germ cells of Strongylocentrotus droebachiensis, the green sea urchin[END_REF]. Assuming that the TEs accumulate mainly in the somatic cells and not in the germinal cells [START_REF] Sellem | Reproductive biology of Paracentrotus lividus in two contrasting habitats of northern Tunisia (south-east Mediterranean)[END_REF], a dilution of the TEs is observed during gametogenesis and a concentration during spawning [START_REF] Guendouzi | Seasonal variation in bioavailability of trace metals in the echinoid Paracentrotus lividus (Lamarck, 1816) from Algerian coastal waters: effect of physiological indices[END_REF]. The spawning period varies by site and is influenced by environmental factors such as temperature, depth, photoperiod, quality and abundance of food [START_REF] Fenaux | Maturation des gonades et cycle saisonnier des larves Arbacia lixula, Paracentrotus lividus et Psammechinus microtuberculatus (Echinides) à Villefranche-sur-Mer[END_REF][START_REF] Byrne | Annual reproductive cycles of the commercial sea urchin Paracentrotus lividus from an exposed intertidal and a sheltered habitat on the west coast of Ireland[END_REF][START_REF] Lozano | Biological cycles and recruitment of Paracentrotus lividus in two contrasting habitats[END_REF][START_REF] Guettaf | Contribution à l'étude de la variabilité du cycle reproductif (indice gonadique et histologie des gonades) chez Paracentrotus lividus (Echinodermata : Echinoidea) en Méditerranée sud-occidentale (Algérie)[END_REF]. The higher gonad weight is probably due to gametogenesis and its decrease to potential spawning. TE concentration tend to decrease in spring and summer when gonadosomatic indices are highest and increase in autumn and winter when spawning has occurred.

The size of sea urchin gonads is not necessarily related to the progress of gametogenesis alone.

They also grow because somatic cells, the nutritive phagocytes, store extensive nutrient reserves before gametogenesis begins [START_REF] Böttger | Care and maintenance of adult echinoderms[END_REF]. Before the formation of gametes, nutritive phagocytes could store reserves and accumulate TEs, which explains the significant positive correlation between the concentration of Zn and the gonadosomatic index. About 80% of the total proteins in the gonads, at the stage of pre-gametogenesis and the renewal of nutrient phagocytes after spawning, are in both genders MYP, the protein involved in the transport of Zn in the gonads [START_REF] Unuma | Quantitative changes in yolk protein and other components in the ovary and testis of the sea urchin Pseudocentrotus depressus[END_REF][START_REF] Unuma | Zinc-binding property of the major yolk protein in the sea urchin -implications of its role as a zinc transporter for gametogenesis[END_REF]. It is also worth noting that the TE concentration is higher during the autumn, the period characterized by the refilling of nutrient reserves in the nutritive phagocytes [START_REF] Walker | Sea urchin gametogenesis-structural, functional and molecular/genomic biology[END_REF]. This supports the hypothesis that TEs are accumulated in nutritive phagocytes.

The temporal variations in TEs concentration are related to the sea urchin's physiological variations. Thus, to monitor TE contamination in the sea urchin gonads, it would be more appropriate to avoid the spawning period. It's also important to take into account the sex of individuals because some TEs are naturally more abundant in males or females. The role of TEs in sea urchins needs to be studied further in order to better interpret their dynamics and their potential consequences for the species.

In addition to physiological factors, other parameters such as food may be involved in these temporal variations. Nutritive phagocytes develop when individuals are well nourished during the pre-gametogenesis and nutrient phagocyte replacement phase [START_REF] Walker | Manipulation of food and photoperiod promotes out-of-season gametogenesis in the green sea urchin, Strongylocentrotus droebachiensis: implications for aquaculture[END_REF].

According to Schlacher-Hoenlinger and Schlacher. (1998), several macrophyte species have levels of some TEs which have a marked seasonality with lower values in summer and higher in winter.

Consumption of food containing higher TE levels in winter may amplify the bioaccumulation process. Moreover, according to [START_REF] Nédélec | Ethologie alimentaire de Paracentrotus lividus dans la baie de Galeria (Corse) et son impact sur les peuplements phytobenthiques[END_REF], Paracentrotus lividus shows an alternation of feeding and fasting phases; the period of fasting or low consumption when the gonads are highly developed [START_REF] Leighton | A comparative study of food selection and nutrition in the abalone, Haliotis rufescens (Swainson), and the sea urchin, Strongylocentrotus purpuratus (Stimpson)[END_REF]. Therefore, the low TE contamination of macrophytes, coupled with the reduced consumption of sea urchins during the summer season, may explain the low concentrations recorded in summer in this study.

Biotic factors are not sufficient to explain the TE temporal dynamics in sea urchin gonads. In the Bonifacio area, for example, gonadosomatic index variations are not related to the TE content recorded. Bioavailability is determined by physiological and biological characteristics but also by external environmental conditions [START_REF] Chapman | Environmental risks of inorganic metals and metalloids: A continuing, evolving scientific odyssey[END_REF]. These conditions, such as temperature, pH, oxygen content and salinity, vary with the seasons. They modify TE availibily and contribute to the temporal variability of TE concentrations in the gonads.

The weight and size of individuals influence the TE concentrations measured in the gonads of Paracentrotus lividus. The assumption being that sea urchins feed more when they are large and thus bioaccumulate more contaminants. The use of TEPI allows a reliable comparison of TE contamination both locally and internationally [START_REF] Wilkes | Intertidal seagrass in Ireland: pressures, WFD status and an assessment of trace element contamination in intertidal habitats using Zostera noltei[END_REF][START_REF] Ternengo | Spatial variations in trace element concentrations of the sea urchin, Paracentrotus lividus, a first reference study in the Mediterranean Sea[END_REF]. The seasons affect the TE concentrations in the sea urchin gonads, so it is not surprising to note that the contamination levels of the sites observed in [START_REF] Ternengo | Spatial variations in trace element concentrations of the sea urchin, Paracentrotus lividus, a first reference study in the Mediterranean Sea[END_REF] in winter are different from the results of the annual TEPI in the present study.

As indicated by [START_REF] Ternengo | Spatial variations in trace element concentrations of the sea urchin, Paracentrotus lividus, a first reference study in the Mediterranean Sea[END_REF], Saint-Florent 2 has a High Contamination Level probably due to the proximity of the asbestos mine and the influence of soil leaching [START_REF] Andral | Evaluation de la contamination chimique du site de Canari: campagne Canari II[END_REF][START_REF] Galgani | Chemical contamination and sediment toxicity along the coast of Corsica[END_REF][START_REF] Kantin | Monitorage de la qualité des eaux et de l'environnement marin -Rapport final -Région Corse. Programme INTERREG IIIA Sardaigne / Corse/ Toscane[END_REF]. High content of Ag has been measured each season and is responsible for the High Level Contamination observed at Saint-Florent 1. In Corsica, the Ag content is very low and only reflects the background level of agriculture [START_REF] Luy | Chemical contamination along the Mediterranean French coast using Posidonia oceanica (L.) Delile aboveground tissues: a multiple trace element study[END_REF] but although this site is now protected, the old mining concessions rich in Ag close to the site could explain this high concentration [START_REF] Gauthier | Mines et mineurs de Corse[END_REF]. Calvi 2, identified as having a High Contamination Level in [START_REF] Ternengo | Spatial variations in trace element concentrations of the sea urchin, Paracentrotus lividus, a first reference study in the Mediterranean Sea[END_REF] and localised near the water treatment plant of the city, presents the lowest level of contamination in Corsica. This is probably due to a bias in winter sampling when some sites have sea urchins at an advanced stage of the nutrient reserve process. Thus, even if sea urchins are harvested in winter to avoid the period of gametogenesis, the results should be interpreted carefully, taking into account the physiological state. It is preferable to combine the TE analysis and histology in order to know the physiological stage of the sea urchins and better assess the contamination. It is also necessary to consider these results carefully because despite the analysis of a large number of TEs, many other contaminants are not taken into account.

To verify the accuracy of these results, it is of interest to compare them with other bioindicators such as Mytilus galloprovencialis (Lamarck, 1819) or Posidonia oceanica. The TEs measured at high concentrations at the different sites of this study were also observed in these bioindicators, in particular for Saint-Florent 2 (e.g. [START_REF] Kantin | Monitorage de la qualité des eaux et de l'environnement marin -Rapport final -Région Corse. Programme INTERREG IIIA Sardaigne / Corse/ Toscane[END_REF][START_REF] Lafabrie | Trace metals assessment in water, sediment, mussel and seagrass species -Validation of the use of Posidonia oceanica as a metal biomonitor[END_REF][START_REF] Lafabrie | Metal contamination of Posidonia oceanica meadows along the Corsican coastline (Mediterranean)[END_REF][START_REF] Richir | Bioassessment of trace element contamination of Mediterranean coastal waters using the seagrass Posidonia oceanica[END_REF]. High concentrations of Ag were observed in Posidonia oceanica at Ile Rousse in [START_REF] Richir | Bioassessment of trace element contamination of Mediterranean coastal waters using the seagrass Posidonia oceanica[END_REF], certainly originating in the same type of source as for the contamination at Saint-Florent 1. In view of these results, the sea urchin Paracentrotus lividus proves to be a good bioindicator and could complement the use of other bioindicators. An ecotoxicological study of this sea urchin would provide information on the contamination at sea and on the influence of the trophic chain and substrates, while the mussel would determine the contamination in the water column, and Posidonia oceanica the contamination on substrate and in the first link of the trophic chain [START_REF] Richir | A reassessment of the use of Posidonia oceanica and Mytilus galloprovincialis to biomonitor the coastal pollution of trace elements: New tools and tips[END_REF]. In addition, depending on the sampling period, one or other of these bioindicators would be more suitable. The spawning period would be avoided for the sea urchin and the mussel while it would be more interesting to study Posidonia oceanica in the spring [START_REF] Kantin | Étude de la contamination par les éléments traces en Méditerranée à l'aide d'organismes bio-intégrateurs[END_REF].

Conclusion

This study highlights, once again, the need to consider biotic factors (gender, reproductive activity) and abiotic factors (physical and chemical characteristics of seawater or food) in the use of sea urchins as bioindicators. Differences in concentration were observed, according to sex, for 11 TEs. This would probably be due to gametogenesis and to antagonistic or synergistic effects between TEs. It is necessary to extend our knowledge to assess the effects of these contaminants on the sea urchin populations. There are temporal variations marked by higher TE concentrations in autumn and winter and, conversely, lower concentrations during the summer season. A dilution effect is observed on the TE content in the gonads during gametogenesis. The use of gonads should be avoided during the spawning period in order to avoid biased comparisons. A difference in concentration of TEs is observed between the different sites. Due to the influence of the soil and the former asbestos mine at Canari, the Saint-Florent area is the most contaminated. On the basis of these results, Paracentrotus lividus appears as an interesting tool for achieving a better understanding of anthropic pressures. Associated with other bioindicators such as Mytilus galloprovencialis or Posidonia oceanica, the study of its ecotoxicological properties would enable managers to act at source and reduce degradation or improve the ecological quality of water bodies.

In addition, it seems that no previous study of the sea urchin, taking all these factors into account, has analyzed so many TEs in a Mediterranean region. These results are therefore essential and can serve as a reference state for the Medirerranean sea.

Figure 1 .Figure 2 .

 12 Figure 1. Location of study coastal areas in Corsica (NW Mediterranean. France), showing the eight sampling stations of Paracentrotus lividus and their characterization. (1 column fitting image)

Table Caption Table 1 .

 Caption1 Mean (mg.kg -1 dw ± SE) trace elements concentrations in the gonad of Paracentrotus lividus according to the season. abcd Dissimilar letters denote significant differences between groups (p-value ˂0.05). p-value: <0.05*; <0.01**; <0.001*** (2 column fitting image)

Table 2 .

 2 Mean (mg.kg -1 dw ± SE) trace elements concentrations (mg.kg-1dry wt) in Paracentrotus

	lividus from 8 stations in Corsica Island (A: Ajaccio; B: Bonifacio; C: Calvi; SF: Saint-Florent; 1:
	reference site; 2: impacted site). abcd Dissimilar letters denote significant differences between
	groups (p-value ˂0.05). p-value: <0.05*; <0.01**; <0.001*** (2 column fitting image or full
	page)

Table 3 .

 3 Mean concentrations (mg.kg -1 dw ± SE) of the 20 trace elements in the male and female gonads of Paracentrotus lividus. P-value: <0.05*; <0.01**; <0.001*** (

1,5 column fitting image)

  Zn 210.167 ± 24.076 a 112.792 ± 14.137 b 144.450 ± 14.711 bc 234.408 ± 35.264 ac <0.0001*** 546

	545	Table 1.
			Winter	Spring	Summer	Autumn	p-value
		Ag	0.112 ± 0.018 a	0.159 ± 0.072 a	0.353 ± 0.101 a	0.187 ± 0.037 a	0.694
		Al	32.888 ± 3.722 a	16.608 ± 1.757 b	9.637 ± 0.954 c	22.936 ± 2.802 a	<0.0001***
		As	37.788 ± 1.845 a	32.083 ± 1.723 a	52.576 ± 3.061 b	53.253 ± 2.685 b	<0.0001***
		Ba	0.305 ± 0.026 a	0.238 ± 0.034 b	0.116 ± 0.008 c	0.380 ± 0.092 a	<0.0001***
		Cd	0.239 ± 0.019 a	0.240 ± 0.020 a	0.285 ± 0.022 ab	0.344 ± 0.027 b	0.0120*
		Co	0.370 ± 0.042 a	0.295 ± 0.025 a	0.302 ± 0.024 a	0.504 ± 0.043 b	<0.0001***
		Cr	1.204 ± 0.226 a	0.891 ± 0.101 a	0.850 ± 0.084 a	1.533 ± 0.193 b	<0.0001***
		Cu	3.893 ± 0.068 a	2.949 ± 0.085 b	1.869 ± 0.041 c	2.731 ± 0.091 b	<0.0001***
		Fe 92.708 ± 12.112 a	60.204 ± 4.489 ab	52.695 ± 3.371 b	117.273 ± 12.784 c <0.0001***
		Li	0.330 ± 0.008 a	0.239 ± 0.010 b	0.131 ± 0.004 c	0.324 ± 0.014 a	<0.0001***
		Mn	2.264 ± 0.104 a	1.033 ± 0.060 b	0.568 ± 0.034 c	1.281 ± 0.101 d	<0.0001***
		Mo	0.343 ± 0.014 a	0.311 ± 0.021 a	0.241 ± 0.022 b	0.346 ± 0.032 a	<0.0001***
		Ni	1.735 ± 0.808 a	0.748 ± 0.157 a	0.549 ± 0.073 a	2.143 ± 0.335 b	<0.0001***
		Pb	0.212 ± 0.036 a	0.131 ± 0.009 b	0.109 ± 0.008 b	0.223 ± 0.026 a	<0.0001***
		Sb	0.169 ± 0.026 a	0.049 ± 0.006 b	0.036 ± 0.003 c	0.074 ± 0.004 d	<0.0001***
		Se	1.990 ± 0.066 a	1.680 ± 0.057 b	1.627 ± 0.041 b	2.082 ± 0.069 a	<0.0001***
		Sn	0.019 ± 0.002 a	0.016 ± 0.002 a	0.009 ± 0.001 b	0.020 ± 0.003 a	<0.0001***
		U	0.991 ± 0.080 a	0.838 ± 0.067 a	0.872 ± 0.071 a	1.508 ± 0.125 b	<0.0001***
		V	3.093 ± 0.217 a	3.133 ± 0.269 a	3.353 ± 0.289 a	5.108 ± 0.366 b	<0.0001***

Table 2 .

 2 Zn 53.287 ± 8.275 264.223 ± 18.069 <0.0001***

	547
		A1	A2	B1	B2	C1	C2	SF1	SF2	P-value
	Ag	0.043 ± 0.012 a 0.107 ± 0.015 bc 0.062 ± 0.008 b	0.015 ± 0.002 d	0.169 ± 0.054 c	0.146 ± 0.025 c	0.942 ± 0.234 e 0.138 ± 0.027 bc <0.0001***
	Al 41.522 ± 6.972 a	21.145 ± 2.824 b	19.512 ± 3.052 b	17.248 ± 2.354 b	9.102 ± 1.670 c	6.583 ± 0.746 c	19.105 ± 2.632 b	29.918 ± 4.144 ab	<0.0001***
	As 31.895 ± 2.094 a	27.492 ± 3.123 b	42.410 ± 2.960 c	25.287 ± 1.427 ab	52.453 ± 3.243 cd	43.078 ± 2.578 c	71.095 ± 4.842 e	57.690 ± 2.935 de	<0.0001***
	Ba	0.268 ± 0.036 abc	0.471 ± 0.182 a	0.223 ± 0.039 abc	0.247 ± 0.024 ab 0.189 ± 0.026 bc 0.212 ± 0.028 abc	0.304 ± 0.061 abc	0.161 ± 0.023 c <0.0001***
	Cd 0.123 ± 0.009 a	0.136 ± 0.016 a	0.246 ± 0.024 b	0.113 ± 0.008 a 0.339 ± 0.035 cd	0.314 ± 0.025 bd	0.491 ± 0.037 e 0.453 ± 0.039 ce <0.0001***
	Co 0.188 ± 0.014 a	0.216 ± 0.019 a 0.321 ± 0.026 bc 0.240 ± 0.020 ac 0.274 ± 0.033 ac	0.209 ± 0.017 a	0.395 ± 0.026 b	1.100 ± 0.078 d <0.0001***
	Cr	0.500 ± 0.052 a	0.505 ± 0.050 a	0.878 ± 0.088 b 0.688 ± 0.087 ab 0.854 ± 0.106 ab	0.657 ± 0.068 ab	1.301 ± 0.102 c	3.572 ± 0.515 d <0.0001***
	Cu 3.129 ± 0.170 ab 2.954 ± 0.143 ab 2.841 ± 0.107 ab 3.432 ± 0.166 a	2.536 ± 0.119 b	2.881 ± 0.118 ab	2.525 ± 0.120 b	2.586 ± 0.124 b <0.0001***
	Fe	76.417 ± 7.730 ab	98.113 ± 11.639 a	61.560 ± 5.072 abc	63.030 ± 8.361 bc	44.018 ± 4.256 c 60.570 ± 7.676 bc	55.663 ± 5.514 bc	186.388 ± 28.712 d	<0.0001***
	Li	0.219 ± 0.017 a	0.250 ± 0.015 abc	0.250 ± 0.014 abc	0.272 ± 0.015 bc	0.258 ± 0.021 abc	0.307 ± 0.018 c	0.249 ± 0.015 abc	0.245 ± 0.021 ab	0.002**
	Mn 1.463 ± 0.165 ab 1.305 ± 0.126 ab 1.149 ± 0.081 ab 1.263 ± 0.110 ab 0.965 ± 0.077 a	1.077 ± 0.097 a	1.019 ± 0.082 a	2.050 ± 0.243 b <0.0001***
	Mo 0.243 ± 0.034 ab 0.220 ± 0.020 b	0.371 ± 0.029 c 0.257 ± 0.026 ab 0.418 ± 0.052 cd 0.248 ± 0.018 abd	0.419 ± 0.039 c	0.306 ± 0.024 acd	<0.0001***
	Ni	0.516 ± 0.112 a 0.729 ± 0.121 ab 0.492 ± 0.051 ab 0.583 ± 0.084 ab 0.983 ± 0.274 ab	0.510 ± 0.069 a	0.824 ± 0.088 b	5.712 ± 1.662 c <0.0001***
	Pb	0.191 ± 0.046 abcd	0.243 ± 0.070 abc	0.188 ± 0.013 ab 0.248 ± 0.029 a	0.129 ± 0.011 cde	0.110 ± 0.008 de	0.138 ± 0.013 bcde	0.102 ± 0.008 e <0.0001***
	Sb	0.077 ± 0.010 abc	0.072 ± 0.016 ab 0.135 ± 0.030 c 0.076 ± 0.011 ab 0.049 ± 0.004 a	0.051 ± 0.004 a	0.092 ± 0.013 bc 0.104 ± 0.043 ab <0.0001***
	Se 1.661 ± 0.066 ab 1.516 ± 0.071 a 2.039 ± 0.096 bc	1.827 ± 0.092 abc	1.831 ± 0.080 bc 1.799 ± 0.073 abc	2.001 ± 0.084 bc 2.086 ± 0.108 c <0.0001***
	Sn	0.011 ± 0.001 a	0.015 ± 0.001 b	0.036 ± 0.003 c	0.034 ± 0.006 c	0.007 ± 0.001 d	0.011 ± 0.003 ad	0.008 ± 0.001 ad 0.006 ± 0.001 d <0.0001***
	U	0.692 ± 0.100 a	0.652 ± 0.065 a	1.078 ±0.102 bc	0.660 ± 0.083 a	1.335 ± 0.170 b	0.818 ± 0.095 ac	1.784 ± 0.168 d 1.398 ± 0.137 bd <0.0001***
	V	2.570 ± 0.365 a	2.647 ± 0.265 a	4.294 ± 0.412 b	2.657 ± 0.405 a 3.775 ± 0.437 ab	2.483 ± 0.263 a	6.419 ± 0.526 c 4.531 ± 0.397 bc <0.0001***
	Zn	161.450 ± 25.331 a	179.567 ± 27.477 a	243.450 ± 59.087 a	134.083 ± 19.116 a	123.133 ± 23.404 a	248.133 ± 42.577 a	181.800 ± 28.013 a	132.017 ± 26.079 a	0.543

Acknowledgments

This work was supported by the University of Corsica (France) and the Univeristy of Liege (Belgium). This study would not have been possible without the financial support of the French Government, the Collectivity of Corsica and the MISTRALS (Mediterranean Integrated STudies at Regional And Local Scales) research program that authors are grateful for their cooperation. This work is part of the STARECAPMED (STAtion of Reference and rEsearch on Change of local and global Anthropogenic Pressures on Mediterranean Ecosystems Drifts) project. The authors are grateful to the scuba diver team of the UMS 3514 Stella Mare for their efforts during the underwater sampling and for providing the necessary facilities. The authors wish to thank M. Paul for proofreading the manuscript. This publication has the MARE publication number MARE393.