Vincent M P Bouchet
email: vincent.bouchet@univ-lille.fr

Fabrizio Frontalini

Fabio Francescangeli

Pierre-Guy Sauriau

Emmanuelle Geslin

Maria Virginia

Alves Martins

Ahuva Almogi-Labin

Simona Avnaim-Katav

Di Letizia

Alejandro Bella

Cearreta

Fabrizio Frontalini

Letizia Di Bella

Alejandro Cearreta

Rodolfo Coccioni

Ashleigh Costelloe

Margarita D Dimiza

Luciana Ferraro

Kristin Haynert

Michael Martínez- Colón

Romana Melis

Magali Schweizer

Maria V Triantaphyllou

Akira Tsujimoto

Brent Wilson

Eric Armynot Du Châtelet

Indicative value of benthic foraminifera for biomonitoring: Assignment to ecological groups of sensitivity to total organic carbon of species from European intertidal areas and transitional waters

Keywords:

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Benthic foraminifera are increasingly recognized as indicators of human-induced stress (e.g., [START_REF] Alve | Benthic foraminiferal distribution and recolonization of formerly anoxic environments in Drammensfjord, southern Norway[END_REF][START_REF] Francescangeli | Palaeo-ecological quality status based on foraminifera of Boulogne-sur-Mer harbour (Pas-de-Calais, Northeastern France) over the last 200 years[END_REF][START_REF] Francescangeli | Multidisciplinary study to monitor consequences of pollution on intertidal benthic ecosystems (Hauts de France, English Channel, France): comparison with natural areas[END_REF][START_REF] Polovodova Asteman | An almost completed pollutionrecovery cycle reflected by sediment geochemistry and benthic foraminiferal assemblages in a Swedish-Norwegian Skagerrak fjord[END_REF], such as oil spills (e.g., [START_REF] Morvan | Foraminifera as potential bioindicators of the "Erika" oil spill in the Bay of Bourgneuf: field and experimental studies[END_REF], drill cutting [START_REF] Mojtahid | Benthic foraminifera as bio-indicators of drill cutting disposal in tropical east Atlantic outer shelf environments[END_REF], heavy metals (e.g., [START_REF] Martins | Assessment of the health quality of Ria de Aveiro (Portugal): Heavy metals and benthic foraminifera[END_REF], urban sewage (e.g., [START_REF] Melis | Seasonal response of benthic foraminifera to anthropogenic pressure in two stations of the Gulf of Trieste (northern Adriatic Sea): the marine protected area of Miramare versus the Servola water sewage outfall[END_REF], and aquaculture (e.g., [START_REF] Debenay | Foraminiferal assemblages as bioindicators to assess potential pollution in mangroves used as a natural biofilter for shrimp farm effluents (New Caledonia)[END_REF]. Recent developments in benthic foraminiferal biotic indices [START_REF] Alve | Foram-AMBI: A sensitivity index based on benthic foraminiferal faunas from North-East Atlantic and Arctic fjords, continental shelves and slopes[END_REF][START_REF] Bouchet | Benthic foraminifera provide a promising tool for ecological quality assessment of marine waters[END_REF][START_REF] Barras | Live benthic foraminiferal faunas from the French Mediterranean coast: towards a new biotic index of environmental quality[END_REF][START_REF] Dimiza | The Foram Stress Index: A new tool for environmental assessment of soft-bottom environments using benthic foraminifera. A case study from the Saronikos Gulf, Greece, Eastern Mediterranean[END_REF][START_REF] Jorissen | Developing Foram-AMBI for biomonitoring in the Mediterranean: Species assignments to ecological categories[END_REF] have provided further opportunities for the application of this meiobenthic group as a biological quality element for ecological quality status (EcoQS) assessment in legislations concerning transitional waters (hereafter TWs; see definition in [START_REF] Mclusky | Transitional waters: a new approach, semantics or just muddying the waters?[END_REF] and marine environments (see review in [START_REF] Sousa | Opportunities and challenges in incorporating benthic foraminifera in marine and coastal environmental biomonitoring of soft sediments: from science to regulation and practice[END_REF]. Foraminiferal indices based either on species diversity [START_REF] Alve | Monitoring strategies for reestablishment of ecological reference conditions: Possibilities and limitations[END_REF][START_REF] Bouchet | Benthic foraminifera provide a promising tool for ecological quality assessment of marine waters[END_REF][START_REF] Bouchet | Erratum to 'Benthic foraminifera provide a promising tool for ecological quality assessment of marine waters[END_REF] or on the sensitivity of species to organic pollution [START_REF] Alve | Foram-AMBI: A sensitivity index based on benthic foraminiferal faunas from North-East Atlantic and Arctic fjords, continental shelves and slopes[END_REF][START_REF] Barras | Live benthic foraminiferal faunas from the French Mediterranean coast: towards a new biotic index of environmental quality[END_REF][START_REF] Dimiza | The Foram Stress Index: A new tool for environmental assessment of soft-bottom environments using benthic foraminifera. A case study from the Saronikos Gulf, Greece, Eastern Mediterranean[END_REF][START_REF] Jorissen | Developing Foram-AMBI for biomonitoring in the Mediterranean: Species assignments to ecological categories[END_REF], have been designed and successfully applied to assess EcoQS of benthic habitats [START_REF] Alve | Intercalibration of benthic foraminiferal and macrofaunal biotic indices: an example from the Norwegian Skagerrak coast (NE North Sea)[END_REF][START_REF] Bouchet | Benthic foraminifera provide a promising tool for ecological quality assessment of marine waters[END_REF][START_REF] Bouchet | Erratum to 'Benthic foraminifera provide a promising tool for ecological quality assessment of marine waters[END_REF]Bouchet et al., , 2018a[START_REF] Bouchet | Benthic foraminifera to assess ecological quality statuses: the case of salmon fish farming[END_REF][START_REF] Damak | Environmental quality assessment of the fish farms' impact in the Monastir Bay (eastern of Tunisia, Central Mediterranean): a benthic foraminiferal perspective[END_REF][START_REF] Denoyelle | Comparison of benthic foraminifera and macrofaunal indicators of the impact of oil-based drill mud disposal[END_REF][START_REF] Dijkstra | Benthic foraminifera as bio-indicators of chemical and physical stressors in Hammerfest harbor (Northern Norway)[END_REF][START_REF] El Kateb | Foraminiferal-based biotic indices to assess the ecological quality status of the Gulf of Gabes (Tunisia): Present limitations and future perspectives[END_REF][START_REF] Francescangeli | Palaeo-ecological quality status based on foraminifera of Boulogne-sur-Mer harbour (Pas-de-Calais, Northeastern France) over the last 200 years[END_REF][START_REF] Jesus | Reconstruction of the palaeo-ecological quality statuses in an anthropogenised estuary using benthic foraminifera: the Santos estuary (Sao Paulo state, SE Brazil)[END_REF][START_REF] Mojtahid | Benthic foraminifera as bio-indicators of drill cutting disposal in tropical east Atlantic outer shelf environments[END_REF][START_REF] Mojtahid | Comparison of benthic foraminiferal and macrofaunal responses to organic pollution in the Firth of Clyde (Scotland)[END_REF][START_REF] Melis | Seasonal response of benthic foraminifera to anthropogenic pressure in two stations of the Gulf of Trieste (northern Adriatic Sea): the marine protected area of Miramare versus the Servola water sewage outfall[END_REF].

In 2011, the informal FOraminiferal Bio-Monitoring (FOBIMO) international working group (WG) was established with the aims (i) to standardize methods for the use of benthic foraminifera in environmental biomonitoring (Schönfeld et al., 2012) and (ii) to unify the effort of "foraminiferologists" to establish a common biotic index to assess the EcoQS [START_REF] Alve | Foram-AMBI: A sensitivity index based on benthic foraminiferal faunas from North-East Atlantic and Arctic fjords, continental shelves and slopes[END_REF][START_REF] Jorissen | Developing Foram-AMBI for biomonitoring in the Mediterranean: Species assignments to ecological categories[END_REF]. The first aim of the FOBIMO WG was to agree to focus on and design an index based on the ecological response of benthic foraminiferal species to total organic carbon (TOC). Specifically, this implied assessing the level of sensitivity/tolerance of foraminiferal taxa to TOC by assigning them to ecological groups (EGs). In the pioneer work of [START_REF] Alve | Foram-AMBI: A sensitivity index based on benthic foraminiferal faunas from North-East Atlantic and Arctic fjords, continental shelves and slopes[END_REF], the authors proposed to assign benthic foraminifera to five EGs following the terminology and definitions used in the macrofauna-based AZTI Marine Biotic Index (AMBI) [START_REF] Borja | A marine biotic index to establish the ecological quality of soft-bottom benthos within European estuarine and coastal environments[END_REF] i.e., sensitive (EGI), indifferent (EGII), tolerant (EGIII), second-order opportunistic (EGIV) and first-order (most) opportunistic (EGV) (see further details in the Material and Methods section). Recently, [START_REF] Jorissen | Developing Foram-AMBI for biomonitoring in the Mediterranean: Species assignments to ecological categories[END_REF] suggested using a more explicit terminology and definitions for benthic foraminifera; describing species belonging to EGIII as "third-order opportunists".

In the species assignments used in macrofaunal AMBI, the peculiar natural features of intertidal, transitional and marine habitats or the various climate regime occurring in different geographical basins are not considered. This means that a species' indicative value is the same in an estuary and in open marine waters or in the Mediterranean Sea and in the Baltic Sea. In fact, the use of a single species classification list means that the indicative value of a species is a static concept; i.e., a species is expected to have a similar sensitivity or tolerance to organic matter (OM) wherever it occurs and regardless its adaptation ability. However, some species are known to be plastic enough to adapt to their environment variability and could change their autecology requirements along environmental gradients (see review in Zettler et al., 2013 and references therein). Hence, the FOBIMO WG decided to establish four sub-WG reflecting four main types of environments i.e. (i) North-East Atlantic and Arctic fjords, continental shelves, and slopes (Alve et al., 2016), (ii) open marine waters in the Mediterranean Sea [START_REF] Jorissen | Developing Foram-AMBI for biomonitoring in the Mediterranean: Species assignments to ecological categories[END_REF], (iii) intertidal areas and TWs (the present contribution), and (iv) tropical environments. Each sub-WG had the aim to define a list of the response to TOC of as many species as possible. Earlier, the NE Atlantic and Arctic Oceans and the Mediterranean Sea open environments sub-WG have already published their respective species (see above). These lists of species can be used in the different sensitivitybased indices designed for benthic foraminifera that use the relative proportion of sensitive, tolerant and opportunistic species to assess EcoQS, either foraminifera-based AMBI (Foram-AMBI, [START_REF] Alve | Foram-AMBI: A sensitivity index based on benthic foraminiferal faunas from North-East Atlantic and Arctic fjords, continental shelves and slopes[END_REF] or comparable methods (e.g., [START_REF] Barras | Live benthic foraminiferal faunas from the French Mediterranean coast: towards a new biotic index of environmental quality[END_REF][START_REF] Dimiza | The Foram Stress Index: A new tool for environmental assessment of soft-bottom environments using benthic foraminifera. A case study from the Saronikos Gulf, Greece, Eastern Mediterranean[END_REF]. These studies show a strong response of marine species to TOC, which is explained by the fact that TOC in such marine systems mainly consists of labile organic matter. However, it is questionable if this method to assign species according to their response to TOC gradients is also applicable in intertidal areas and TWs, where TOC is reflecting labile and refractory organic matter [START_REF] Pusceddu | Enzymatically hydrolyzable protein and carbohydrate sedimentary pools as indicators of the trophic state of detritus sink systems: a case study in a Mediterranean coastal lagoon[END_REF]. Noticeably, salt marsh sediments commonly exhibit very high TOC values, due to the halophile vegetation, responsible for the presence of large quantities of poorly reactive organic matter (Armynot du Châtelet et al., 2009a;[START_REF] Leorri | Refractory organic matter in salt marshes-effect on C sequestration calculations[END_REF][START_REF] Middelburg | Organic carbon isotope systematics of coastal marshes[END_REF].

This paper presents the first results of the sub-WG on intertidal areas and TWs along the European Atlantic coasts from the Belgian-French border down to Portugal and in the Mediterranean Sea.

The construction of ecological species lists is hampered by the fact that benthic foraminiferal taxonomy may vary considerably among studies, which complicated a reliable assignment in EGs. Specifically, foraminiferal species are traditionally defined on morphological criteria and are therefore mostly morphospecies. Molecular studies have shown that some of these morphospecies include cryptic or pseudocryptic species [START_REF] Darling | The genetic diversity, phylogeography and morphology of Elphidiidae (Foraminifera) in the Northeast Atlantic[END_REF][START_REF] Hayward | Morphological distinction of molecular types in Ammonia -towards a taxonomic revision of the world's most commonly misidentified foraminifera[END_REF][START_REF] Richirt | Morphological distinctions of three Ammonia phylotypes occurring along European coasts[END_REF].

Another complication is that intertidal areas and TWs are characterized by strong environmental gradients and high natural variability of physico-chemical parameters (e.g., salinity, temperature, grain-size, dissolved oxygen; Elliott and Quintino 2007) coupled with natural organic matter enrichment [START_REF] Pusceddu | Enzymatically hydrolyzable protein and carbohydrate sedimentary pools as indicators of the trophic state of detritus sink systems: a case study in a Mediterranean coastal lagoon[END_REF]. Intertidal and TWs, therefore, often behave as naturally stressed environments [START_REF] Dauvin | Paradox of estuarine quality: benthic indicators and indices, consensus or debate for the future[END_REF][START_REF] Elliott | The Estuarine Quality Paradox, environmental homeostasis and the difficulty of detecting anthropogenic stress in naturally stressed areas[END_REF], but also commonly experience high levels of anthropogenic stresses such as aquaculture [START_REF] Bouchet | Influence of oyster culture practices and environmental conditions on the ecological quality of intertidal mudflats in the Pertuis Charentais (SW France): a multi-index approach[END_REF], habitat destruction (e.g., agricultural uses, coastal reinforcements), urban sewage and industrial discharges [START_REF] Armynot Du Châtelet | Foraminiferal proxies for pollution monitoring in moderately polluted harbors[END_REF][START_REF] Morvan | Foraminifera as potential bioindicators of the "Erika" oil spill in the Bay of Bourgneuf: field and experimental studies[END_REF]. Species distribution in these environments is the result of the complex interplay between natural and human-induced stressors. Therefore, it is challenging to achieve a reliable assignment of benthic foraminiferal species from these environments to EGs according to species response by considering only TOC.

In this context, the present study aims at (i) developing an objective protocol for the species' assignment to EGs, (ii) investigating if it is possible to assign benthic foraminiferal species from intertidal areas and TWs from the considered geographical zones to the five EGs described in [START_REF] Alve | Foram-AMBI: A sensitivity index based on benthic foraminiferal faunas from North-East Atlantic and Arctic fjords, continental shelves and slopes[END_REF] according to species responses to sediment TOC content, (iii) if applicable, validating the established lists by testing them using a sensitivity-based index on separate and independent datasets from the same geographic regions, and (iv) testing the hypothesis that species ecological requirements may vary between habitats/ecosystems and along latitudinal gradients by comparing species assignment lists from the present study.

Because of the particular characteristics of foraminiferal habitats and communities, we decided to present the foraminiferal species assignments split in two lists: one for the European Atlantic and one for the Mediterranean region. The recently developed Foram-AMBI [START_REF] Alve | Foram-AMBI: A sensitivity index based on benthic foraminiferal faunas from North-East Atlantic and Arctic fjords, continental shelves and slopes[END_REF], adapted from AMBI for benthic foraminifera, was used to test the reliability of these ecological species lists.

Material and Methods

Ecological groups of sensitivity to TOC

Benthic macrofaunal species are traditionally assigned to five groups of sensitivity to OM (e.g., [START_REF] Borja | A marine biotic index to establish the ecological quality of soft-bottom benthos within European estuarine and coastal environments[END_REF][START_REF] Glémarec | Perturbations apportées à la macrofaune benthique de la baie de Concarneau par les effluents urbains et portuaires[END_REF][START_REF] Hily | Dynamique de la recolonisation par la macrofaune d'un substrat dragué à proximité du port de Brest[END_REF][START_REF] Simboura | Benthic indicators to use in ecological quality classification of Mediterranean soft bottom marine ecosystems, including a new biotic index[END_REF] based on the seminal work of [START_REF] Pearson | Macrobenthic succession in relation to organic enrichment and pollution of the marine environment[END_REF]. Species are meant to be indicative of the prevailing environmental conditions; i.e., the level of organic carbon enrichment where they are found. Taken from [START_REF] Grall | Using biotic indices to estimate macrobenthic community perturbations in the Bay of Brest[END_REF] and [START_REF] Borja | A marine biotic index to establish the ecological quality of soft-bottom benthos within European estuarine and coastal environments[END_REF], the following characteristics were used by [START_REF] Alve | Foram-AMBI: A sensitivity index based on benthic foraminiferal faunas from North-East Atlantic and Arctic fjords, continental shelves and slopes[END_REF] and [START_REF] Jorissen | Developing Foram-AMBI for biomonitoring in the Mediterranean: Species assignments to ecological categories[END_REF] to assign benthic foraminiferal species to the five EGs considering their response to TOC. These characteristics are used in the present study:

• Group I (EGI). "Sensitive species" are sensitive to TOC enrichment. Their relative abundance is highest at the lowest TOC values and drops to zero as organic carbon concentration increases.

• Group II (EGII). "Indifferent species" are indifferent to initial stages of organic carbon enrichment. They never dominate the assemblage. They occur in low relative abundance over a broad range of organic carbon concentrations, but are absent at very high concentrations.

• Group III (EGIII). "Tolerant species" are tolerant to excess organic carbon enrichment.

They may occur at low TOC; their highest frequencies are stimulated by organic carbon enrichment but they are absent at very high organic carbon concentrations. This group has been termed "third-order opportunistic species" by [START_REF] Jorissen | Developing Foram-AMBI for biomonitoring in the Mediterranean: Species assignments to ecological categories[END_REF].

• Group IV (EGIV). "second-order opportunistic species" show a clear positive response to organic carbon enrichment with maximum abundances between the maxima of EGIII and EGV.

• Group V (EGV). "first-order opportunistic species" exhibit a clear positive response to excess organic carbon enrichment with maximum abundances at a higher stress level induced by organic load than species belonging to EGIV. At even higher TOC concentrations, foraminifera are not able to survive.

Based on Hily's model [START_REF] Glémarec | Perturbations apportées à la macrofaune benthique de la baie de Concarneau par les effluents urbains et portuaires[END_REF][START_REF] Hily | Variabilité de la macrofaune benthique dans les milieux hypertrophiques de la Rade de Brest[END_REF][START_REF] Majeed | Organic matter and biotic indices on the beaches of north Brittany[END_REF], the theoretical succession of the relative abundance of each EG, was adapted to benthic foraminiferal species along a TOC gradient. According to [START_REF] Jorissen | Developing Foram-AMBI for biomonitoring in the Mediterranean: Species assignments to ecological categories[END_REF], the five categories are distributed as follows (Fig. 1).

Figure 1. Theoretical graph providing the succession of benthic foraminifera belonging to the five EGs according to their response to organic carbon enrichment.

Criteria to select datasets

Only previous studies in areas that strictly follow the definition of intertidal and TWs were selected. In the European Water Framework Directive (WFD, 2000/60/EC), TWs are defined as « bodies of surface water in the vicinity of river mouths which are partially saline in character as a result of their proximity to coastal waters but which are substantially influenced by freshwater flows » (European Communities, 2000, p 6). In the Mediterranean Sea, TWs also include mesohaline, poly-euhaline and hyperhaline lagoons [START_REF] Reizopoulou | Transitional waters Mediterranean geographic intercalibration group. Benthic invertebrates ecological assessment methods; EU 29561[END_REF]. We decided to follow the definition of [START_REF] Mclusky | Transitional waters: a new approach, semantics or just muddying the waters?[END_REF] who specified the different types of water bodies belonging to intertidal and TWs in the context of the implementation of the WFD and further marine legislations (see Table 1). Three further criteria had to be met to retain the datasets used for the assignments:

 the study had to be based on living benthic foraminifera. Note that all datasets used in the present study are based on rose Bengal-stained fauna;

 the foraminiferal and TOC data had to be from the same station (less than 1 meter from the sampling point); when the authors of the study only provide the OM content (studies 10; 12 and 18, Table 3), it was converted to TOC using the following formula: LOI = 2 TOC [START_REF] Barillé-Boyer | Correction for particulate organic matter as estimated by loss on ignition in estuarine ecosystems[END_REF][START_REF] Frangipane | Comparison of loss on ignition and thermal analysis stepwise method for determination of sedimentary organic matter[END_REF];

 only samples containing >50 stained specimens were considered following [START_REF] Alve | Foram-AMBI: A sensitivity index based on benthic foraminiferal faunas from North-East Atlantic and Arctic fjords, continental shelves and slopes[END_REF].

All studies from the English Channel/European Atlantic except one (see Appendix A) are based on the >63 m fraction, whereas in the Mediterranean Sea studies are based on the fraction >63 or >125 m (Appendix B). In total, 21 studies were selected from the English Channel/European Atlantic intertidal and TWs (Fig. 2, Appendix A) and 21 ones from the Mediterranean Sea (Fig. 2, Appendix B). The complete datasets are presented in Bouchet et al. (submitted).

Due to lack of standardization, different methods were used in the different studies to measure TOC; from the classical loss-on-ignition (LOI) to the more sophisticated use of an elemental analyzer (EA). While the latter directly quantifies TOC concentration, the LOI measures the OM content. It is still often used in large surveys because it allows for a quick and cheap measurement of sedimentary organic matter [START_REF] Luczak | Simple standard procedure for the routine determination of organic matter in marine sediment[END_REF]. It is generally accepted that LOI may overestimate TOC content compared to EA [START_REF] Barillé-Boyer | Correction for particulate organic matter as estimated by loss on ignition in estuarine ecosystems[END_REF]. In the datasets from the English Channel/European Atlantic coast, the ranges of TOC obtained with LOI and EA are fairly similar. Apart from one study in the Ebro delta, all the studies in the Mediterranean Sea used an EA to measure TOC content. Therefore, TOC data from the different studies should be compared with caution.

Species names were homogenized among studies following the World Register of Marine Species (WoRMS, Hayward et al., 2020a). Only accepted scientific names from WoRMS are used in this study, and the unique AphiaID identifier is reported for each species.

The Aphia platform is an infrastructure aiming at capturing taxonomic and related data and information [START_REF] Vandepitte | How Aphia-the platform behind several online and taxonomically oriented databases-can serve both the taxonomic community and the field of biodiversity informatics[END_REF]. Each taxon added to the Aphia database receives a unique and persistent identifier, the AphiaID. Once assigned to, the name and its corresponding ID cannot be physically deleted from the database, ensuring that the information is not lost.

Species assignment according to relation with TOC content

Indicator species are meant to provide information about environmental conditions.

The knowledge of the environmental requirements of a species can be used to detect changes in abiotic conditions or to assess the environmental health of the study area. The assignment of foraminiferal species to the five EGs involves determining which species are more abundant at low, medium and high TOC concentrations.

This can be achieved in different ways. The macrofaunal AMBI list is based on a literature review allowing an inventory of the individual species responses to organic matter gradients, completed in some cases by experts' opinion [START_REF] Borja | Chapter three -Forever young: the successful story of a marine biotic index[END_REF]. If the latter sounds rather subjective, the former should be reasonably objective. The Foram-AMBI lists for open marine environments of the NE Atlantic and Arctic Oceans [START_REF] Alve | Foram-AMBI: A sensitivity index based on benthic foraminiferal faunas from North-East Atlantic and Arctic fjords, continental shelves and slopes[END_REF] and the Mediterranean Sea [START_REF] Jorissen | Developing Foram-AMBI for biomonitoring in the Mediterranean: Species assignments to ecological categories[END_REF] are both based on an objective review of available datasets, sometimes (in case of inconclusive data) with a small contribution of best expert judgment [START_REF] Jorissen | Developing Foram-AMBI for biomonitoring in the Mediterranean: Species assignments to ecological categories[END_REF]. These publications included a few plots exemplifying species-specific relative abundance patterns plotted against TOC, to better explain the followed methodology.

In the present study's effort to produce lists of foraminiferal species for the European Atlantic and Mediterranean intertidal and TWs, the aim was to seek for an objective method for species assignments in order to avoid using « best expert judgment ». The weightedaveraging (WA) optimum and tolerance approach was used [START_REF] Birks | Diatoms and pH reconstruction[END_REF][START_REF] Ter Braak | Unimodal models to relate species to environment[END_REF]. The idea behind WA is that in a coastal lagoon with a certain TOC range, benthic foraminifera with their TOC optimum close to the coastal lagoon's TOC concentrations will most likely be the most abundant species. A simple and ecologically reasonable estimate of a benthic foraminiferal species' optimum is the average of all TOC values for intertidal areas and TWs in which the species occurs, weighted by the species relative abundance (WA regression). The estimated optimum allows to give an objective assessment of the species environmental requirements. To summarize, the WA optimum method is rapid, easy to implement, theoretically sound, robust [START_REF] Birks | Diatoms and pH reconstruction[END_REF] and leads to an objective assessment of species-specific indicative values.

Foram-AMBI

Foram-AMBI was used to test the species lists. It is adapted from the marine macrofauna AMBI [START_REF] Borja | A marine biotic index to establish the ecological quality of soft-bottom benthos within European estuarine and coastal environments[END_REF], and was first introduced by [START_REF] Alve | Foram-AMBI: A sensitivity index based on benthic foraminiferal faunas from North-East Atlantic and Arctic fjords, continental shelves and slopes[END_REF] for fjords, continental shelves and slopes in the North-East Atlantic and Arctic Oceans. Foram-AMBI uses the relative abundance of selected species to assess the EcoQS of marine systems.

Foram-AMBI is calculated using the AMBI formula [START_REF] Borja | A marine biotic index to establish the ecological quality of soft-bottom benthos within European estuarine and coastal environments[END_REF]:

Foram-AMBI = {(0 x %EGI) + (1.5 x %EGII) + (3 x %EGIII) + (4.5 x %EGIV) + ( 6x %EGV)}/100

For the validation and test phase of the species lists using Foram-AMBI, awaiting a specific calibration for foraminifera, EcoQS were determined following the criteria established for macrofaunal AMBI (Table 2, [START_REF] Borja | A marine biotic index to establish the ecological quality of soft-bottom benthos within European estuarine and coastal environments[END_REF]. In view of the first available results, the class limits must probably be redefined for foraminifera.

Table 2. Criteria for determining EcoQS according to Foram-AMBI (following criteria of macrofauna AMBI, [START_REF] Borja | A marine biotic index to establish the ecological quality of soft-bottom benthos within European estuarine and coastal environments[END_REF] and correspondence with sediment TOC [START_REF] Bakke | Development of sediment quality criteria in Norway[END_REF][START_REF] Viaroli | Biogeochemical indicators as tools for assessing sediment quality/vulnerability in transitional aquatic ecosystems[END_REF].

EcoQS and associated color code

Bad Poor Moderate Good High Foram-AMBI >5.5 4.3-5.5 3.3-4.3 1.2-3.3 <1.2
Total organic carbon (%) >4.1 3.4-4.1 2.5-3.4 2.0-2.5 <2.0

Testing the ecological assignment lists

In order to test our species assignment to EGs according to their response to TOC, Foram-AMBI was applied on two independent datasets from the English Channel/European Atlantic coast area and the Mediterranean Sea, which were not included in the master tables for calculation of the species assignment (to avoid circular arguments). Great attention was paid to find studies where a clear organic carbon gradient enrichment was observed.

In the English Channel/European Atlantic coast area, Foram-AMBI was applied on a study of the effects of oyster farming on living benthic foraminifera in SW France [START_REF] Bouchet | Dynamique et réponse fonctionnelle des foraminifères et de la macrofaune benthiques en zone ostréicole dans les pertuis charentais[END_REF]. Oyster farming leads to organic matter enrichment in the surrounding environment [START_REF] Bouchet | Influence of oyster culture practices and environmental conditions on the ecological quality of intertidal mudflats in the Pertuis Charentais (SW France): a multi-index approach[END_REF]. The sampling stations were located in four different unvegetated intertidal mudflats harboring oyster parks actively used by shellfish operators:

Rivedoux (R), Yves (Y), Charente (CH) and Daires (D) (Fig. 3; more details on the sampling sites in [START_REF] Bouchet | Influence of oyster culture practices and environmental conditions on the ecological quality of intertidal mudflats in the Pertuis Charentais (SW France): a multi-index approach[END_REF]. At all sampled stations, benthic foraminifera and macrofauna were sampled at the same time, allowing for a sound comparison between Foram-AMBI and AMBI, which is based on benthic macro-invertebrates (AMBI results were published in [START_REF] Bouchet | Influence of oyster culture practices and environmental conditions on the ecological quality of intertidal mudflats in the Pertuis Charentais (SW France): a multi-index approach[END_REF]. In the Mediterranean Sea, Foram-AMBI was tested on data from the harbor of Cagliari in the South of Sardinia in Italy [START_REF] Schintu | Heavy metal accumulation in surface sediments at the port of Cagliari (Sardinia, western Mediterranean): Environmental assessment using sequential extractions and benthic foraminifera[END_REF] where a clear OM enrichment gradient was observed. This harbor includes the oil terminal of one of the largest oil refineries in the Mediterranean Sea. Sampling was carried out in four unvegetated zones of the harbor: (i) stations H1-H7: the historical port (HP), (ii) stations L1-L3: the Santa Gilla lagoon, (iii) stations G1-G10: the gulf facing the industrial areas, and (iv) stations B1-B3: control stations (Fig. 4).

Statistical analysis

The next two steps were followed to assign benthic foraminiferal species to the five EGs:

1. The WA optimum and tolerance were computed for each species to determine its preference with respect to TOC (%) using the optimos.prime R package [START_REF] Sathicq | Calculating autoecological data (optima and tolerance range) for multiple species with the 'optimos.prime' R package[END_REF].

2. Species assignment to EGs was done as follows: if a species had an optimum in the TOC range 0-2%, the species was assigned to EGI; in the range 2-2.5%, the species was assigned to EGII; in the range 2.5-3.4%, 3.4-4.1%, and above 4.1% to EGII, EGIII, EGIV and EGV. This is based on TOC-derived EcoQS (see Table 2; [START_REF] Bakke | Development of sediment quality criteria in Norway[END_REF][START_REF] Viaroli | Biogeochemical indicators as tools for assessing sediment quality/vulnerability in transitional aquatic ecosystems[END_REF]. One species' list per region was produced.

Typical example for each EG is shown for each region to visualize pattern of species response along the TOC gradient. A locally weighted scatterplot smooth line (LOESS) was fitted to each scatter plot. Marginal plots were added to each scatter plot to show the frequency of distribution of occurrences along the TOC gradient. The median of the distribution of the occurrences was also computed.

Two master tables (available in Bouchet et al., submitted) were used in the abovedescribed procedure. These master tables included TOC percentages and species relative abundances data of the 21 studies from the English Channel/European Atlantic coast (587 samples) and the 21 studies from the Mediterranean Sea (301 samples).

As the distribution of OM, AMBI and Foram-AMBI was normally distributed All these calculations were made using the statistical language R version 3.6.3 (R Core Team, 2020).

Results

Species assignments to EGs according to total organic carbon

The English Channel/European Atlantic coast

In the English Channel/European Atlantic intertidal and TWs datasets, TOC ranges between 0 and 16% (Appendix A). Figure 5 presents a typical example of species-response curves for each of the five EGs. Most of the five figured species have a characteristic unimodal distribution pattern. However, the relative abundance distribution of Cribroelphidium excavatum and C. williamsoni were bimodal, with peaks at 0-1% and 7-12%, and at 2-4% and 7-9%, respectively. In total, 77 species from this geographic region were assigned: 22 in EGI, 13 in EGII, 23 in EGIII, 6 in EGIV and 13 in EGV (Appendix C).

Despite their high optimum values, typical salt marsh species (Balticammina pseudomacrescens, Entzia macrescens and Trochammina inflata), which are dominant in environments characterized by very high natural TOC values, were not assigned. This is further explained in the discussion.

The Mediterranean Sea

In the Mediterranean Sea intertidal and TWs datasets, TOC ranges between 0.07 and 17.8% (Appendix B).

Comparison of species assignments between the existing lists of benthic foraminifera

In total, the two lists established in this study for the English Channel and the European Atlantic and the Mediterranean Sea intertidal and TWs have 35 species in common (Table 3). Among these 35 species, ten species were assigned to the same EG in both regions, ten with a difference in their assignment of only one category, whereas fifteen taxa showed an offset of two categories or more. Very surprisingly, the Elphidiidae Cribroelphidium excavatum, C. gunteri and C. williamsoni, Bolivina spp. and Quinqueloculina spp. exhibited an offset of three to four categories.

The English Channel/European Atlantic coast

In the Pertuis Charentais dataset, there is a significant positive correlation between Foram-AMBI and OM, and between AMBI and OM (R 2 = 0.67 p = 0.001 and R 2 = 0.66 p = 0.001; Fig. 7A and7B; respectively). All foraminiferal species occurring at the sampling sites are assigned in EGs. Foram-AMBI ranged from 1.9 to 3.3 (Fig. 7A) and AMBI from 1.2 to 4 (Fig. 7B). They are significantly correlated (R 2 = 0.56, p < 0.01; Fig. 7C). Based on Foram-AMBI, EcoQS varied between good and moderate (Table 8). Both indices agreed that the best EcoQS was at the reference sampling station R1. Assessments of EcoQS derived from Foram-AMBI and AMBI partially match but were in some cases contradictory. There was 50% of full agreement between the two indices derived-EcoQS (Fig. 7A and7B). Table 1).

The Mediterranean Sea

In the harbor of Cagliari, there was a significant positive correlation between Foram-AMBI and organic matter (R 2 = 0.42, p = 0.001; Fig. 7D). The relative abundance of species unassigned to EGs varied from 0.4 to 16.9%. Stations with the lowest organic matter (OM)

values exhibited High EcoQS (Fig. 7D). With increasing OM content, Foram-AMBI-derived EcoQS changed to good i.e., slightly disturbed. There was a cluster of six samples with low TOC and low Foram-AMBI while all other samples had higher TOC and higher Foram-AMBI values.

Discussion

Natural variability of intertidal and TWs and reference conditions

The promising results of the present study do not, however, warrant an easy implementation of Foram-AMBI and comparable methods in intertidal areas and TWs. Biotic indices based on the indicator species concept, like AMBI, are not fully reliable to assess EcoQS in these water body types (i.e., [START_REF] Borja | The application of a Marine Biotic Index to different impact sources affecting soft-bottom benthic communities along European coasts[END_REF][START_REF] Blanchet | Use of biotic indices in semi-enclosed coastal ecosystems and transitional waters habitats -implications for the implementation of the European Water Framework Directive[END_REF][START_REF] Bouchet | Influence of oyster culture practices and environmental conditions on the ecological quality of intertidal mudflats in the Pertuis Charentais (SW France): a multi-index approach[END_REF][START_REF] Salas | Evaluation of the applicability of a marine biotic index to characterize the status of estuarine ecosystems: the case of Mondego estuary (Portugal)[END_REF]. In fact, the natural features of these ecosystems hamper the disentanglement of natural-and human-induced changes. In particular, silt, clay and OM sedimentary contents are naturally high in intertidal areas and TWs, promoting tolerant and opportunistic species, while sensitive species naturally decline [START_REF] Elliott | The Estuarine Quality Paradox, environmental homeostasis and the difficulty of detecting anthropogenic stress in naturally stressed areas[END_REF][START_REF] Munari | The performance of benthic indicators of ecological change in Adriatic coastal lagoons: throwing the baby with the water?[END_REF]. In intertidal and TWs, benthic communities could therefore be naturally similar to those found in anthropogenically-disturbed areas [START_REF] Blanchet | Use of biotic indices in semi-enclosed coastal ecosystems and transitional waters habitats -implications for the implementation of the European Water Framework Directive[END_REF][START_REF] Munari | The performance of benthic indicators of ecological change in Adriatic coastal lagoons: throwing the baby with the water?[END_REF]. Consequently, pristine, naturally disturbed intertidal areas and TWs could easily be misclassified in moderate to bad EcoQS (the so-called "estuarine quality paradox"; [START_REF] Dauvin | Paradox of estuarine quality: benthic indicators and indices, consensus or debate for the future[END_REF][START_REF] Dauvin | The estuarine quality paradox: is it possible to define an ecological quality status for specific modified and naturally stressed estuarine ecosystems?[END_REF][START_REF] Elliott | The Estuarine Quality Paradox, environmental homeostasis and the difficulty of detecting anthropogenic stress in naturally stressed areas[END_REF], severely complicating the decision-making [START_REF] Blanchet | Use of biotic indices in semi-enclosed coastal ecosystems and transitional waters habitats -implications for the implementation of the European Water Framework Directive[END_REF][START_REF] Muniz | Testing the applicability of a Marine Biotic Index (AMBI) to assessing the ecological quality of softbottom benthic communities, in the South America Atlantic region[END_REF][START_REF] Quintino | The derivation, performance and role of univariate and multivariate indicators of benthic change: case studies at differing spatial scales[END_REF][START_REF] Salas | Evaluation of the applicability of a marine biotic index to characterize the status of estuarine ecosystems: the case of Mondego estuary (Portugal)[END_REF]. The natural features of intertidal and TWs may also affect the outcome of sensitivity-based foraminiferal indices like Foram-AMBI and comparable methods. The definition of water-body type specific or local reference conditions is absolutely necessary to overcome such limitations. In fact, in order to assess the health of marine systems, it is mandatory to define reference conditions or to set targets according to marine legislations. For instance, a more robust assessment of EcoQS for TWs was obtained with benthic foraminifera using site-specific local reference conditions in the Oslofjord (Norway) [START_REF] Dolven | Defining past ecological status and in situ reference conditions using benthic foraminifera: A case study from the Oslofjord, Norway[END_REF], in the Boulogne-sur-Mer harbour (France) [START_REF] Francescangeli | Palaeo-ecological quality status based on foraminifera of Boulogne-sur-Mer harbour (Pas-de-Calais, Northeastern France) over the last 200 years[END_REF] and in the Santos estuary (Brazil) [START_REF] Jesus | Reconstruction of the palaeo-ecological quality statuses in an anthropogenised estuary using benthic foraminifera: the Santos estuary (Sao Paulo state, SE Brazil)[END_REF]. Furthermore, geochemical analyses of dated sediment cores can be used in combination with benthic foraminifera to determine ecological reference conditions in TWs [START_REF] Klootwijk | Monitoring environmental impacts of fish farms: comparing reference conditions of sediment geochemistry and benthic foraminifera with the present[END_REF][START_REF] Hess | Defining ecological reference conditions in naturally stressed environments -How difficult is it?[END_REF].

Assignment of benthic foraminifera from intertidal and TWs to EGs according to TOC response patterns

It is generally accepted that EcoQS obtained with AMBI (and Foram-AMBI) are valid only if species unassigned to EGs account for less than 20% [START_REF] Borja | Guidelines for the use of AMBI (AZTI's Marine Biotic Index) in the assessment of the benthic ecological quality[END_REF]. In the two validation tests of the Foram-AMBI, there were virtually no unassigned species in the Pertuis Charentais dataset, and only 16.9% in the Harbor of Cagliari, warranting the validity of the EcoQS assessment. This suggests that enough species from intertidal and TWs have been assigned to test the lists over a large spatial scale in Europe.

For decades, increased supply of OM to coastal waters has been considered to have a negative effect on ecosystems [START_REF] Pearson | Macrobenthic succession in relation to organic enrichment and pollution of the marine environment[END_REF]. As a consequence, TOC has become a typical indicator of environmental stress. Salt marshes are, per definition, vegetated by halophilic plants which are terrestrial in origin [START_REF] Middelburg | Organic carbon isotope systematics of coastal marshes[END_REF]. Therefore, marsh habitats are expected to be characterized by high TOC (Armynot du [START_REF] Armynot Du Châtelet | Benthic foraminifera in transitional environments in the English Channel and the southern North Sea: A proxy for regional-scale environmental and paleo-environmental characterisations[END_REF] whether or not they are impacted by human activities and discharge of organic carbon.

Consequently, in salt marshes, TOC may be not a suitable indicator of human-induced stress.

In the present study, TOC was the only ecological factor considered for species assignment to EGs. Commonly, in salt marshes, sediment contains a mix of refractory and labile OM (Armynot du Châtelet et al., 2009a;[START_REF] Leorri | Refractory organic matter in salt marshes-effect on C sequestration calculations[END_REF][START_REF] Middelburg | Organic carbon isotope systematics of coastal marshes[END_REF]. Noticeably, the labile (food) directly stimulates growth and reproduction, while the refractory (terrestrial origin) TOC is not directly bioavailable [START_REF] Pusceddu | Quantity and bioavailability of sediment organic matter as signatures of benthic trophic status[END_REF]. Furthermore, environmental conditions encountered at low tide (e.g., aerial exposure, low salinity, thermal stress) [START_REF] Alve | Marginal marine environments of the Skagerrak and Kattegat: a baseline study of living (stained) benthic foraminiferal ecology[END_REF][START_REF] Francescangeli | Does elevation matter? Living foraminiferal distribution in a hyper tidal salt marsh (Canche Estuary, Northern France)[END_REF] as well as seasonal changes (e.g., desiccation

or increased salinity during the dry season) further constrain foraminiferal species [START_REF] Cearreta | Recent salt marsh development and natural regeneration of reclaimed areas in the Plentzia Estuary, N. Spain[END_REF][START_REF] De Rijk | Salt marsh foraminifera from the Great Marshes, Massahusetts: environmental controls[END_REF]. Species distribution patterns in salt marshes are therefore mainly the outcome of a complex interplay between a number of natural stressors (see review in [START_REF] Murray | Ecology and applications of benthic foraminifera[END_REF].

In case we would have rigorously applied the method to use the WA optimum to classify species to EG's, the dominant species in salt marshes Entzia macrescens, Trochammina inflata, Haplophragmoides wilberti and Balticammina pseudomacrescens would all have been assigned to EGIV/EGV, because of the consistently very high TOC values found in these environments. It implicitly means that we would interpret them as (strongly) opportunistic, and, additionally, that a high relative frequency of these taxa would indicate a polluted environment. The studied species distribution patterns are largely restricted to salt marshes where they naturally occur in high abundances [START_REF] Alve | Marginal marine environments of the Skagerrak and Kattegat: a baseline study of living (stained) benthic foraminiferal ecology[END_REF]Debenay et al., 2000;[START_REF] Cearreta | Recent salt marsh development and natural regeneration of reclaimed areas in the Plentzia Estuary, N. Spain[END_REF][START_REF] Fatela | Environmental constraints of foraminiferal assemblages distribution across a brackish tidal marsh (Caminha, NW Portugal)[END_REF][START_REF] Scott | Pacific Rim marsh foraminiferal distributions: implications for sea-level studies[END_REF]. The assignment of these typical salt marsh species to EGs IV and V would, in view of their systematically very high frequency in natural, apparently unpolluted, salt marshes, appear to be incorrect. For this reason, we did not assign typical salt marsh species to EGs.

Test of the species' assignments

In both validation datasets, Foram-AMBI yielded a positive significant correlation with organic matter content indicating that this sensitivity index calculated with the present study lists reflects the change in EcoQS along an OM gradient. In the Pertuis Charentais, the un-impacted station R1 had the lowest value, indicating a higher proportion of sensitive species. It was therefore possible to discriminate between this reference station and the impacted ones. Note that all stations are situated at the same level in the tidal zone and in similar habitats, so that differences in EcoQS are not due to the natural features of each of the sampling stations. In the harbor of Cagliari, Foram-AMBI adequately distinguished between high and good EcoQS.

In the Pertuis Charentais, a significant positive correlation between Foram-AMBI and AMBI values (based on macrofauna) confirmed previous correlations found between foraminiferal and macrofaunal communities and indices [START_REF] Alve | Intercalibration of benthic foraminiferal and macrofaunal biotic indices: an example from the Norwegian Skagerrak coast (NE North Sea)[END_REF]Bouchet et al., 2018b). However, only a 50% agreement in terms of EcoQS between Foram-AMBI and AMBI was reported. In this study, EcoQS boundaries established for AMBI [START_REF] Borja | A marine biotic index to establish the ecological quality of soft-bottom benthos within European estuarine and coastal environments[END_REF] were used to infer EcoQS based on Foram-AMBI. Discrepancies in EcoQS assessment may suggest that specific Foram-AMBI-adapted criteria should be developed. For instance, intercalibration between the two indices may help improving the use of Foram-AMBI. This was successfully done in Norway when adapting the Norwegian Quality Index based on macrofauna (NQI m ) to the foraminiferal one (NQI f ) [START_REF] Alve | Intercalibration of benthic foraminiferal and macrofaunal biotic indices: an example from the Norwegian Skagerrak coast (NE North Sea)[END_REF].

The results of the tests showed that the classification, obtained with the calculation of the WA "optimum" values for each species, probably adequately reflects differences in species tolerance of organic load-related stress. The outcome was a reliable assessment of EcoQS in the Pertuis Charentais and in the Harbor of Cagliari. The weighted-averaging optimum method allowed for an objective assessment of the ecological requirement of each species along the TOC gradient. As for now in European intertidal and TWs, more tests on other independent data sets are, nevertheless, needed to further confirm the findings of this work, and most likely to improve the present study lists of species.

Potential problems due to benthic foraminiferal taxonomy

Different taxonomical schools co-exist in the foraminiferal community. Unfortunately, this sometimes leads to major inconsistencies with regards to species identification. Scientists working on other biological groups like macro-algae, phytoplankton or benthic macroinvertebrates organize workshops on a regular basis to compare and homogenise their taxonomy. After 20 years of workshops, scientists working on planktonic foraminifera have now agreed and published a global taxonomy of Cretaceous and Paleogene species and genera. In this way, they manage to minimize the remaining taxonomical inconsistency. This issue has also been raised by previous studies assigning benthic foraminifera into EGs [START_REF] Alve | Foram-AMBI: A sensitivity index based on benthic foraminiferal faunas from North-East Atlantic and Arctic fjords, continental shelves and slopes[END_REF][START_REF] Jorissen | Developing Foram-AMBI for biomonitoring in the Mediterranean: Species assignments to ecological categories[END_REF]). It appears relevant to keep organizing benthic foraminifera taxonomical workshops to intercalibrate the different taxonomical schools.

Since taxonomy is still mostly based on morphological criteria, taxonomical names used for the same foraminiferal species are rather inconsistent between researchers. For marine species, the WoRMS database provides an authoritative and comprehensive list of marine species including also information on synonymy. It is continuously revised, ensuring that it is kept up-to-date. Benthic foraminifera are included in the database (Hayward et al., 2020a), but foraminiferal studies rarely refer to it, unlike researchers working on benthic macro-invertebrates, for instance, for whom WoRMS is the database of reference for species names. It was therefore a true challenge to "homogenise" species names between studies to build up an accurate and reliable master table for this present work. To clearly and easily compare different foraminiferal studies, similar species concepts and consistent use of names are necessary. At the moment, WoRMS seems to be a relevant option to archive accepted scientific names (and associated synonyms) of benthic foraminiferal species. However, to ensure a high quality and to obtain the acceptance of the WoRMS database by a larger part of the community, the section concerning foraminiferal species needs the input of much more researchers working on foraminifera (Hayward et al., 2020b). Additionally, molecular analyses and a detailed morphological analysis based on SEM images of sequenced specimens have to be combined to confirm or refute the taxonomical identifications. The contribution of molecular studies has yet to be implemented in WoRMS.

Phylogeographic studies of (pseudo)cryptic species

In all studies considered for the species assignments, the taxonomy of benthic foraminifera was based on morphological criteria. However, cases such as cryptic species (different biological species with identical morphologies), morphological convergence (unrelated species showing the same morphological characteristics) or ecophenotypic variations (same species looking different under different ecological conditions) are common, and make it virtually impossible to determine species by using morphology alone [START_REF] Darling | The genetic diversity of planktic foraminifera and the global distribution of ribosomal RNA genotypes[END_REF][START_REF] Haynes | Supposed pronounced ecophenotypy in foraminifera[END_REF][START_REF] Pawlowski | Diversity and geographic distribution of benthic foraminifera: a molecular perspective[END_REF]. The wide occurrence of cryptic species, which is starting to be visible through the increasing number of molecular studies, is a challenge for environmental biomonitoring [START_REF] Feckler | Cryptic species diversity: an overlooked factor in environmental management?[END_REF]. In benthic foraminifera, the presence of cryptic species is now well documented in Elphidiidae [START_REF] Darling | The genetic diversity, phylogeography and morphology of Elphidiidae (Foraminifera) in the Northeast Atlantic[END_REF][START_REF] Pillet | Molecular phylogeny of Elphidiidae (foraminifera)[END_REF][START_REF] Schweizer | Molecular identification of Ammonia and Elphidium species (foraminifera, Rotaliida) from the Kiel Fjord (SW Baltic Sea) with rDNA sequences[END_REF] and Ammonia [START_REF] Bird | The genetic diversity, morphology, biogeography, and taxonomic designations of Ammonia (Foraminifera) in the Northeast Atlantic[END_REF][START_REF] Hayward | Morphological distinction of molecular types in Ammonia -towards a taxonomic revision of the world's most commonly misidentified foraminifera[END_REF][START_REF] Richirt | Morphological distinctions of three Ammonia phylotypes occurring along European coasts[END_REF]. The present evidence suggests that different cryptic lineages in these taxa may have different ecological requirements, based on the observation of physiological [START_REF] Jauffrais | Ultrastructure and distribution of kleptoplasts in benthic foraminifera from shallow-water (photic) habitats[END_REF] or spatial distribution pattern differences [START_REF] Bird | The genetic diversity, morphology, biogeography, and taxonomic designations of Ammonia (Foraminifera) in the Northeast Atlantic[END_REF][START_REF] Richirt | Morphological distinctions of three Ammonia phylotypes occurring along European coasts[END_REF]. Potentially, in the intertidal areas and TWs of the English Channel and the European Atlantic Ocean, one or several phylotypes of C. excavatum may be sensitive (e.g., highest abundances at low TOC) while others may be more opportunistic (e.g., highest abundances at high TOC). In such cases, it is important to combine morphological analyses and molecular identification (also called DNA barcoding or genetic characterisation) [START_REF] Hayward | Morphological distinction of molecular types in Ammonia -towards a taxonomic revision of the world's most commonly misidentified foraminifera[END_REF][START_REF] Schweizer | Molecular phylogeny of the foraminiferal genus Uvigerina based on ribosomal DNA sequences[END_REF][START_REF] Schweizer | Molecular phylogeny of common Cibicidids and related Rotaliida (Foraminifera) based on small subunit rDNA sequences[END_REF]. Recently, a study on the genus Ammonia combined morphological and molecular taxonomies to determine morphological criteria for identifying the different phylotypes [START_REF] Richirt | Morphological distinctions of three Ammonia phylotypes occurring along European coasts[END_REF].

It is now possible to implement these morphological criteria in routine surveys to differentiate between the different pseudo-cryptic Ammonia species T1, T2 and T6. However, these morphological criteria for Ammonia tepida have only been available since 2019. In the studies used here, researchers pooled most Ammonia specimens under the name A. tepida.

Until data on the ecological requirements for each of the Ammonia tepida phylotypes are available, we decided to follow the taxonomy used in the different studies even though we are fully aware that this is still an ongoing problem to be solved. This issue is however not specific to the work of our FOBIMO sub-WG on intertidal and TWs, as the other sub-WGs also had to cope with the same situation [START_REF] Alve | Foram-AMBI: A sensitivity index based on benthic foraminiferal faunas from North-East Atlantic and Arctic fjords, continental shelves and slopes[END_REF][START_REF] Jorissen | Developing Foram-AMBI for biomonitoring in the Mediterranean: Species assignments to ecological categories[END_REF]. Such improvements obtained by combining morphological and molecular analyses are important, considering that environmental biomonitoring uses the indicative value of species. However, their taxonomical identification needs to be cost effective, rapid and accurate.

Phylogeographic studies may help to better distinguish and identify possible cryptic species, and to describe the distribution pattern of the different phylotypes. Such studies, including large environmental surveys, allowing to understand the ecological requirements of each cryptic lineages, would complement morphological taxonomy. It will further help to assign species to the relevant EG. Therefore, ecological studies on cryptic species presents a major topic for further scientific research projects.

Geographical variability of benthic foraminiferal EG assignments

The results of this study show that there can be an offset of up to four categories in species assignments to EGs depending on habitat type (different water-body types in TWs) or latitudinal gradient (from Northern Europe to the Mediterranean Sea). Noticeably, Elphidiidae, Bolivina spp. and Quinqueloculina spp., which are often the most abundant species, exhibited such large variations. Similar variations along latitudinal gradients and habitats types have been reported for macro-invertebrate species. For instance, the bivalve Cerastoderma glaucum, the polychaeta Ampharete baltica and Hediste diversicolor showed varying tolerance to OM content under different salinity regimes [START_REF] Zettler | On the myths of indicator species: issues and further consideration in the use of static concepts for ecological applications[END_REF].

In benthic foraminifera, these differences between areas and environments may be explained by taxonomic discrepancies between the different regions (the same name given to different species or different names given to the same species) or plastic adaptation of the same species to different areas. For example, Cribroelphidium gunteri and C. oceanense/C. oceanensis, which share similar morphological features, are often mixed [START_REF] Barbieri | Benthic foraminifera or Ostracoda? Comparing the accuracy of paleoenvironmental indicators from a Pleistocene lagoon of the Romagna coastal plain(Italy)[END_REF][START_REF] Murray | British Nearshore Foraminiferids. Synopses of the British Fauna (New Series)[END_REF]. It is therefore rather difficult to conclude if the assignment of C. gunteri in different EGs in the two studied regions (EGIII in the English Channel and Eastern Atlantic and EGV in the Mediterranean Sea) is due to local adaptation i.e., plasticity or simply the result of taxonomical misidentification. The same may also apply to Bolivina variabilis (EGIII in the English Channel and Eastern Atlantic and EGI in the Mediterranean Sea), since the taxonomy is complex in bolivinids, leading to some confusions between morphological species. Furthermore, some of these morphospecies are known to shelter different cryptic or pseudocryptic species that are not separated when using the morphological concept, but could have different ecological requirements. For example, Cribroelphidium excavatum is assigned to EGI in the English Channel and Eastern Atlantic while it is assigned to EGIII in the Mediterranean Sea. The taxonomic situation of this morphospecies is rather confused because of its high intraspecific morphological variability, leading to the description of ecophenotypes, sub-species and species [START_REF] Feyling-Hanssen | The foraminifer Elphidium excavatum (Terquem) and its variant forms[END_REF]. However, molecular studies showed that some of C. excavatum ecophenotypes can be raised to species [START_REF] Darling | The genetic diversity, phylogeography and morphology of Elphidiidae (Foraminifera) in the Northeast Atlantic[END_REF]. Similarly, Quinqueloculina seminula [START_REF] Kaushik | Morphological variation in the porcelaneous benthic foraminifer Quinqueloculina seminula (Linnaeus, 1758): genotypes or morphotypes? A detailed morphotaxonomic, molecular and ecological investigation[END_REF] contains cryptic species which might exhibit different ecological features explaining the assignment to EGV in the English Channel and Eastern Atlantic while it is assigned to the EGI in the Mediterranean Sea. This is however highly speculative; it may also be hypothesized that wrong taxonomical identification or plasticity in C. excavatum and Q. seminula may explain such differences.

Explaining the geographical variability of benthic foraminiferal EG assignments observed in this study remains quite uncertain. Describing and understanding the response of benthic foraminiferal species to TOC and to other natural and human-induces stressors in different habitats and along latitudinal gradients requires further work. This is in line with the increasing use of generalized linear mixed models (GLMMs) in biostatistics since non-normal data that involve random effects (e.g., multimodal data based on different observers and/or environments) need to be carefully and appropriately handled [START_REF] Bolker | Generalized linear mixed models: a practical guide for ecology and evolution[END_REF].

Conclusion

The present study shows that the classification probably adequately reflects differences in species tolerance of organic load-related stress. The tests of the species' lists on the two validation data sets can be considered a promising start which is worthy to pursue using other data sets. The assignment of typical salt marsh species was however not possible, since their classification in the opportunist EGs was not reflecting their natural ecological

Figure 2 .

 2 Figure 2. Map showing the geographical distribution of the 42 studies used to assign the

Figure 3 .

 3 Figure 3. Map of the sampling stations in the Pertuis Charentais (CH: Charente, D: Daires,

Figure 4 .

 4 Figure 4. Map of the sampling stations in the harbor of Cagliari in Sardinia (Italy). HP =

(

  Kolmogorov-Smirnov test, p > 0.01), parametric statistics were used for the Cagliari and Pertuis parameters. The relation between Foram-AMBI, AMBI and organic matter (TOC values being not available for the Pertuis Charentais and Cagliari datasets) was quantified by mean of a Pearson's correlation coefficient R 2 .

Figure 5 .

 5 Figure 5. Scatter plot fitted with a locally weighted scatterplot smooth line to visualize

  Figure 6. Scatter plot fitted with locally weighted scatterplot smooth line to visualize species

Figure 7 .

 7 Figure 7. Relationship between indices and OM in the Pertuis Charentais (A, B and C) and in

Table 1 .

 1 Water body types of intertidal areas and TWs according to McLusky and Elliott

	(2007); the "Artificial water body" type (European communities, 2000, p 6) was added to
	complete the original table.
	Water body types	Natural features
		Tidally dominated at the seaward part; salinity notably
	Classical estuary	reduced by freshwater river inputs; riverine dominance
		landward
		Limited exchange with the coastal area through a restricted
	Lentic non-tidal lagoon	mouth; separated from sea by sand or shingle banks, bars,
		coral, etc., shallow area, tidal range <50 cm
	Lentic micro-tidal lagoon	As above but with tidal range >50 cm
	Ria	Drowned river valley, some freshwater inputs; limited exchanges with coastal waters
	Delta	Low energy, characteristically shaped, sediment dominated, river mouth area; estuary outflow
	Coastal freshwater/brackish	Outflow of estuary or lagoon, notably diluted salinity and
	water plume	hence differing biota than surrounding coast
	Semi-enclosed bay/lagoon	Low energy, notably limited exchange with the open sea waters
		Harbours and docks, constructed dredging pools and coastal
	Artificial water body	water bodies connected to the sea, created by human
		activities.

Table 3 .

 3 Comparison of species assignments between the English Channel and EuropeanAtlantic intertidal and TWs (ECEA) and the Mediterranean Sea intertidal and TWs (MedS).

		ECEA MedS		ECEA MedS
	Ammobaculites balkwilli	II	III	Cribroelphidium williamsoni	III	I
	Ammonia parkinsoniana	II	I	Elphidium advenum	III	I
	Ammonia tepida	III	III Haynesina depressula	I	I
	Asterigerinata mamilla	I	I	Haynesina germanica	III	III
	Aubignyna perlucida	V	V Hopkinsina atlantica	V	IV
	Bolivina dilatata	III	II	Hopkinsina pacifica	V	V
	Bolivina ordinaria	II	V Miliammina fusca	II	III
	Bolivina pseudoplicata	II	V	Miliolinella subrotunda	II	I
	Bolivina striatula	V	I	Nonionoides turgidus	III	III
	Bolivina variabilis	III	I	Planorbulina mediterranensis	I	I
	Bolivina spathulata	III	IV	Quinqueloculina carinatastriata	V	I
	Bulimina elongata	IV	III	Quinqueloculina jugosa	V	III
	Bulimina marginata	IV	II	Quinqueloculina lata	V	II
	Buliminella elegantissima	III	III	Quinqueloculina seminula	V	I
	Cibicidoides lobatulus	I	I	Quinqueloculina stelligera	V	I
	Cribroelphidium excavatum	I	III Rosalina bradyi	II	I
	Cribroelphidium gunteri	III	V	Stainforthia fusiformis	IV	V
	Cribroelphidium poeyanum	I	III

Test of the validity of the species' lists

  requirements. Furthermore, this study does not ensure that Foram-AMBI and comparable methods will perform in all European waters. There is hence an urgent need to apply and test sensitivity-based foraminiferal indices in different ecosystems and against different pollution sources. Otherwise, the community of foraminiferologists also suffers from severe taxonomical heterogeneity. A great effort must be devoted in the near future to encourage intercalibration exercises. Datasets from the Mediterranean Sea coast used for species assignments. Location of the different areas is shown on Figure2. TOC: total organic carbon, LOI: loss of ignition. Assigned species from the English Channel/European Atlantic intertidal and TWs per ecological group (EG). For each species, accepted scientific name and AphiaID (source: WoRMS), optimum and tolerance range to TOC are also reported. Balticammina pseudomacrescens, Trochammina inflata and Enztia macrescens are not assigned (NA). Assigned species from the Mediterranean Sea intertidal and TWs per ecological group (EG). For each species, accepted scientific name and AphiaID (source: WoRMS), optimum and tolerance range to TOC are also reported. Trochammina inflata, Enztia macrescens and Haplophragmoides wilberti are not assigned (NA).

	English Channel English Channel English Channel English Channel English Channel English Channel Atlantic Atlantic Atlantic Atlantic Atlantic Atlantic Atlantic Sea Mediterranean Sea Paratrochammina 5 6 7 8 9 10 11 12 13 14 15 16 29 30 (Lepidoparatrochammina) haynesi France Canche estuary France Canche estuary France Canche estuary France Authie estuary France Somme estuary France Bay of Veys France Crouesty harbour France Loire estuary France Aiguillon bay France Aiguillon Bay/Ré Island France Ronce Perquis Spain Plentzia estuary Spain Ria de Vigo Italy Lesina lagoon Italy Venice lagoon 736766 Elphidium cuvillieri 113263 Ammotium cassis 114029 laevigata 112642 1.0 Quinqueloculina Buliminella elegantissima 113747 Peneroplis pertusus 112815 0.9 Atlantic Portugal Ria de Aveiro 18 Atlantic Portugal Ria de Aveiro 19 Atlantic Portugal Ria de Aveiro 20 Atlantic Portugal Ria de Aveiro 21 Atlantic Portugal Guadiana estuary Appendix B. Datas et Region Countr y Local study area 22 Mediterranean Sea Spain Ebro delta 23 Mediterranean Sea France Bagès-Sigean lagoon Mediterranean Sea Italy Marano and Grado lagoon Classical estuary Classical estuary Classical estuary Classical estuary Classical estuary Coastal freshwater/brackish water plume Artificial water body Classical estuary Coastal freshwater/brackish water plume Coastal freshwater/brackish water plume Coastal freshwater/brackish water plume Classical estuary Ria Lentic tidal lagoon Lentic tidal lagoon 1.8 1.2 2.5 1.8 0.8 3.8 2.6 2.2 3.1 0.2 4.2 I Cribroelphidium poeyanum Francescangeli et al. (2017) 103 Armynot du Châtelet et al. (2018) 63 Francescangeli (2017) 12 Francescangeli (2017) 12 Francescangeli (2017) 16 Bouchet (unpublished) 6 Armynot du Châtelet (2003) 14 Mojtahid et al. (2016) 32 Armynot du Châtelet et al. (2009b) 41 Bouchet et al. (2009) 3 Bouchet et al. (2007) 5 Cearreta et al. (2002) 5 Diz et al. (2006) 28 Frontalini et al. (2010) 11 Coccioni et al. (2009) 12 I Elphidium advenum 113254 > 150 > 63 I Cribroelphidium 1026171 III Aubignyna perlucida 466408 113244 3.2 2.5 1.3 4.9 III jugosa 112641 0.3 2.8 I Nonionoides turgidus 466471 3.0 Ria Martins et al. (2015) 53 Ria Martins et al. (2013) 29 Ria Martins et al. (2010) 15 Ria Martins et al. (2016) 31 Classical estuary Camacho et al. (2014) 42 Water body type Reference Numb er of sample s Foram size fraction Delta Benito et al. (2016) 36 > 63 Lentic non-tidal lagoon Foster et al. (2012) 11 > 125 Lentic tidal lagoon Melis (unpublished data) 11 > 63 32 Mediterranean Sea Greece Saronikos gulf Semi-enclosed bay/lagoon Portela (2017) 11 > 125 33 Mediterranean Sea Greece Saronikos gulf Semi-enclosed bay/lagoon Dimiza et al. (2016) 10 > 125 34 Mediterranean Sea Greece Evoikos gulf Semi-enclosed bay/lagoon Goreija (2013) 8 > 125 35 Mediterranean Sea Greece Kavala bay Semi-enclosed bay/lagoon Delliou (2013) 6 > 125 36 Mediterranean Sea Turke y Gulf of Izmir Semi-enclosed bay/lagoon Bergin et al. (2006) 9 > 250 37 Mediterranean Sea Israel Timsah pond Flako-Zaritsky et al. > 63 Accepted Tolerance Tolerance Accepted Scientific Accepted gerthi Reophax nana 114011 1.8 1.3 2.5 I Stainforthia fusiformis 113070 Elphidium pulvereum 528472 1.8 1.0 3.3 I Balticammina pseudomacrescens 556254 Discorbis vilardeboanus 113154 1.8 1.0 3.4 I Bulimina marginata 113042 Leptohalysis scottii 578704 1.9 1.5 2.4 I Cornuspira involvens 112488 Appendix D. Accepted Scientific Accepted Tolerance Tolerance Accepted Tolerance CHN Elemental analyser CHN Elemental analyser CHN Elemental analyser CHN Elemental analyser CHN Elemental analyser LOI LOI LECO-CS200® analyser LOI LOI LOI Walkey method LECO-CS200® analyser analyser CHN Elemental analyser 3.3 2.9 3.3 1.7 11.2 10.0 2.5 4.1 7.6 4.8 2.3 4.0 LOI LOI LOI LOI CHN Elemental analyser TOC method LOI CHN Elemental analyser CHN Elemental analyser CHN Elemental analyser CHN Elemental analyser CHN Elemental analyser CHN Elemental analyser Hach method CHN Elemental Tolerance 3.4 1.8 3.4 2.8 3.5 3.2 3.6 1.5 Tolerance Ammonia beccarii 112849 1.1 0.3 3.4 I Textularia bocki 114267 3.2 2.7 3.7 Porosononion granosum 954808 1.1 0.5 2.2 I Miliammina fusca 114064 3.2 2.4 4.3 Massilina secans 163641 1.1 0.3 4.7 I Discorbinella bertheloti 113143 3.3 2.5 4.3 Quinqueloculina stelligera 920885 1.1 0.3 4.5 I Adelosina pulchella 112538 3.3 1.8 6.1 Nonionoides grateloupii 418051 1.2 0.7 2.1 I Ammonia batava subsp. compacta 1381806 3.4 2.6 4.5 Appendix C. Accepted Scientific Name AphiaID Optimum -+ EG Name AphiaID Optimum -Cribroelphidium poeyanum 113244 0.6 0.2 1.9 I Eilohedra vitrea 466420 2.7 2.3 Subanomalina pauperata 847845 0.9 0.5 1.9 I Miliammina obliqua 465995 2.7 1.6 Spirillina vivipara 113737 2.0 1.1 3.7 II Cribrostomoides jeffreysii 114035 3.6 3.6 Rosalina bradyi 113167 2.0 1.3 3.0 II Eggerelloides scaber 113938 3.7 2.6 Name AphiaID Optimum -+ EG Accepted Scientific Name AphiaID Optimum -+ Ammonia parkinsoniana 418095 1.2 0.2 6.1 I Bolivina spathulata 112988 3.6 1.5 8.5 Cribroelphidium incertum 113240 0.1 0.1 0.2 I Adelosina cliarensis 112529 2.0 0.9 4.1 Quinqueloculina berthelotiana 112816 1.2 0.7 2.2 I Porosononion subgranosus 556479 3.8 2.7 5.2 Cribroelphidium Cribroelphidium magellanicum 113242 2.0 1.4 2.9 II Bulimina elongata 933974 3.9 2.5 Sigmavirgulina tortuosa 113392 0.2 0.1 0.5 I Bulimina marginata 113042 2.1 1.2 3.8 Bolivina variabilis 112998 1.3 0.4 4.1 I Hopkinsina atlantica 582285 3.9 3.1 4.8 Lentic non-tidal lagoon (2011) 2 analyser 38 Mediterranean Sea Israel Betzet, Naaman, Poleg, Lachish estuaries Classical estuary Avnaim-Katav et al. (2016) 7 > 63 CHN Elemental analyser 39 Mediterranean Sea Egypt Abu-Qir bay Semi-enclosed bay/lagoon Elshanawany et al. (2011) 18 > 63 LECO-CS200® analyser 40 Mediterranean Sea Tunisi a Djerba lagoon Lentic non-tidal lagoon El Kateb et al. (2018) 9 > 63 CHN Elemental analyser 41 Mediterranean Sea Tunisi a Monastir bay Semi-enclosed bay/lagoon Damak et al. (2019) 10 > 125 Walker and Black method Asterigerinata mamilla 112933 1.1 0.6 2.0 I williamsoni 1026169 2.7 0.9 Neocorbina nitida N.D. 1.3 0.7 2.3 I Ammobaculites balkwilli 163639 2.0 1.4 3.1 II Hopkinsina atlantica 582285 4.1 2.0 Cibicides refulgens 112877 0.2 0.1 0.7 I Quinqueloculina lata 112644 2.2 0.6 8.5 Peneroplis planatus 112817 1.4 0.6 3.3 I Bolivina ordinaria 112978 4.2 3.4 5.1 Bolivinellina translucens 526512 2.7 2.3 Haynesina depressula 113293 1.3 0.8 2.2 I Ammonia tepida 112857 2.8 1.1 Ammotium morenoi 736481 2.1 1.2 3.7 II Trochammina inflata 114348 4.1 1.9 Sigmoilina costata 112693 0.2 0.1 0.5 I Valvulineria bradyana 112960 2.2 1.2 3.9 Adelosina Quinqueloculina Astrononion stelligerum 113552 0.2 0.1 0.7 I Bolivina dilatata 112973 2.2 0.9 5.7 mediterranensis 112536 1.4 0.5 4.2 I Bolivina pseudoplicata 112982 4.3 3.3 5.5 Lepidodeuterammina eddystonensis 817119 1.4 0.8 2.5 I Tiphotrocha comprimata 114331 2.8 1.3 Elphidium pereirum N.D. 1.5 1.3 1.7 I Nonionella stella 113604 2.8 2.0 Cibicidoides ungerianus 112889 2.1 1.3 3.4 II seminula 112674 4.3 1.9 Haplophragmoides manilaensis 417577 2.1 1.6 2.7 II Asterigerinata mamilla 112933 0.4 0.2 1.1 I Rectuvigerina phlegeri 113755 2.3 1.3 4.0 Miliolinella subrotunda 112564 1.5 0.5 4.4 I Cribroelphidium gunteri 1026170 4.7 2.1 10.7 Rotaliammina concava 850049 4.3 2.3 Haynesina depressula 113293 0.5 0.2 1.2 I Ammobaculites exiguus 417589 2.3 2.0 2.7 Discorinopsis aguayoi 417645 1.5 0.4 6.1 I Rosalina irregularis 113172 4.8 4.1 5.6 Quinqueloculina Miliolinella subrotunda 112564 2.1 0.8 5.4 II Entzia macrescens 742429 4.7 2.4 Elphidium complanatum 113261 0.5 0.2 1.2 I Quinqueloculina jugosa 112641 2.4 1.1 5.0 carinatastriata 466057 1.6 0.8 3.0 I Aubignyna perlucida 466408 5.2 1.8 15.3 42 Mediterranean Sea Tunisi a Bizerte lagoon Lentic non-tidal lagoon Alves Martins et al. (2015) 10 > 63 CHN Elemental analyser Cribroelphidium excavatum 254680 1.6 0.6 4.0 I Bolivina spathulata 112988 2.9 2.4 Gavelinopsis praegiri 113159 1.6 0.9 2.7 I Fursenkoina complanata 466392 2.9 2.5 Bolivina pseudoplicata 112982 2.2 1.1 4.5 II Aubignyna hamblensis 146404 5.1 3.6 Rosalina macropora 113173 0.7 0.2 3.1 I Vertebralina striata 112785 2.4 1.0 5.5 Quinqueloculina Quinqueloculina Cibicidoides lobatulus 988323 0.7 0.3 1.9 I Ammonia tepida 112857 2.4 0.9 6.1 bicostata 417701 1.6 0.8 3.1 I Quinqueloculina oblonga 912989 5.2 3.5 7.8 Cribroelphidium 24 Mediterranean Sea Italy Sardinia island Semi-enclosed bay/Lagoon Schintu et al. (2015) 18 Bolivinellina Miliammina fusca 114064 2.3 1.2 4.3 II carinatastriata 466057 5.2 4.2 Rosalina bradyi 113167 0.8 0.3 2.1 I Ammobaculites balkwilli 163639 2.4 1.4 4.2 williamsoni 1026169 1.6 0.9 2.7 I Quinqueloculina costata 523480 5.9 3.2 11.0 > 63 LOI 25 Mediterranean Sea Italy Santa Gilla Lentic tidal lagoon Frontalini et al. (2009) 17 > 63 CHN Elemental analyser 26 Mediterranean Sea Italy Orbetello Lentic non tidal lagoon Frontalini et al. (2010) 7 > 63 CHN Elemental analyser 27 Mediterranean Sea Italy Naples harbour Artificial water body Ferraro et al. (2006) 54 > 125 CHN Elemental analyser 28 Mediterranean Sea Italy Varano lake Lentic non tidal lagoon Frontalini et al. (2013) 24 > 125 CHN Elemental analyser Mediterranean > 63 CHN Elemental Elphidium margaritaceum 113279 1.6 0.8 3.1 I pseudopunctata 112999 3.0 2.3 Planorbulina mediterranensis 113634 1.6 1.1 2.4 I Bulimina gibba 113040 3.1 2.5 Bolivina ordinaria 112978 2.3 0.7 7.2 II Elphidium articulatum 113257 5.3 2.9 Triloculina trigonula 112772 0.8 0.2 2.4 I Ammoscalaria runiana 113919 2.4 2.0 3.0 Siphonaperta aspera 593433 1.6 2.9 0.8 I Trochammina inflata 114348 8.2 3.9 17.3 Polysaccammina hyperhalina 867465 1.6 0.6 4.5 I Nonionoides turgidus 466471 3.2 2.5 Ammoscalaria pseudospiralis 113918 2.4 1.5 3.7 II Quinqueloculina lata 112644 5.4 2.3 Textularia agglutinans 114264 0.8 0.5 1.3 I Bulimina elongata 933974 2.5 1.3 4.9 Spirillina vivipara 113737 1.6 0.3 8.8 I Entzia macrescens 742429 8.4 3.9 17.9 Lepidodeuterammina ochracea 114306 1.7 1.1 2.5 I Siphotrochammina lobata 522046 3.2 1.1 Cibicidoides lobatulus 988323 1.7 0.7 3.8 I Cribroelphidium gunteri 1026170 3.2 1.2 Bolivina robusta 466349 1.7 1.0 2.8 I Textularia earlandi 114273 3.2 1.3 Arenoparrella mexicana 417609 1.7 0.8 3.5 I Bulimina elegans 901990 3.2 1.2 Ammonia parkinsoniana 418095 2.4 2.1 2.7 II Bolivina striatula 112989 6.2 3.4 Elphidium crispum 113262 0.8 0.3 2.4 I Cribroelphidium excavatum 254680 2.5 2.0 3.3 Bolivina striatula 112989 1.7 0.4 7.9 I Hopkinsina pacifica 113728 10.2 7.7 13.7 Bolivina dilatata 112973 2.5 1.7 3.6 III Quinqueloculina stelligera 920885 7.1 3.2 Haynesina germanica 113294 2.5 1.0 6.1 III Hopkinsina pacifica 113728 7.4 4.8 Cassidulina carinata 183041 0.9 0.7 1.0 I Triloculina marioni 112763 2.6 1.3 5.0 Quinqueloculina Rosalina globularis 113171 0.9 0.2 4.2 I Cribroelphidium selseyense 754247 2.6 1.7 4.1 seminula 112674 1.8 0.7 4.7 I Stainforthia fusiformis 113070 10.4 8.5 12.8 Planorbulina Cycloforina contorta 112516 1.8 0.8 3.9 I Haplophragmoides wilberti 113955 11.1 8.4 14.8 Bolivina variabilis 112998 2.5 1.0 6.4 III Fusulina lucida 909789 7.6 4.2 mediterranensis 113634 0.9 0.3 2.7 I Buliminella elegantissima 113747 2.7 0.4 16.2 Adelosina longirostra 112535 1.8 1.0 3.5 I Quinqueloculina Elphidium advenum 113254 0.9 0.2 4.0 I Haynesina germanica 113294 3.0 1.5 5.8 Adelosina milletti 522161 1.9 1.1 3.3 I	0.03-13.6 0.03-13.6 1.2-3.8 0.7-1.8 0.3-2.2 0.8-1.55 0.1-16 0.1-2.6 6.1-13.6 9.1-9.9 3.6-5.9 2-4 4.7-10.4 8-15.1 3.6 6.5 III 12.5 V III 12.1 V 3.6-9.3 0.1-7.4 1-10.7 0.6-10.7 1.4-3.8 0.2-8.9 % TOC range 0.89-17.8 0.1-4.5 0.4-3.2 0.6-3.1 0.3-0.9 0.1-0.8 2.4-6.7 10.6-Tolerance III III 6.5 IV 4.2 NA 3.8 IV 8.5 IV III III III III IV + EG 3.1 III 4.6 3.6 IV 5.2 IV EG IV II IV III 5.9 IV II IV 12.6 0.1-2.5 0.1-6.7 0.07-0.9 8.2 III 8.7 V II V 3.2 III 7.1 9.1 II NA V II III 5.9 III 4.0 9.7 V V II 8.0 V V II III 9.0 NA III V 0.5-5.25 3.2-5.9 3.5 III 3.5 III 7.1 III V V III 0.5-3 6.3 V III V 0.5-10.1 1.7-2.5 2.84-7.11 0.12-5.73 1.1-4.2 3.9 III 3.7 9.6 III NA V III 4.0 12.7 III NA V III 9.0 III 8.7 III 7.9 III 8.6 III 11.6 III V V 15.8 V 11.6 III V III NA V 13.7 III V III

Acknowledgments

The authors are grateful to Elisabeth Alve and Frans J. Jorissen for their comments on earlier versions of the manuscript that greatly helped to improve it. Maria-Belen Sathicq helped V.M.P.B. in handling the optimos.prime R package. Jean-Pierre Debenay is thanked for his help and advices at the very early stage of this work. The authors are grateful to the Swiss National Science Foundation, the Agence de l'Eau Artois-Picardie, the Communauté d'Agglomération du Boulonnais, the Université de Lille, the Université du Littoral Côte d'Opale, the Laboratoire d'Océanologie et de Géosciences for their financial support to FOBIMO workshops in Fribourg (Switzerland), Wimereux (France) and Texel (The Netherlands); and to Silvia Spezzaferri and Henko de Stigter for organizing and hosting the workshops in Fribourg and Texel. The authors would like to thank the editor and the anonymous reviewer for their comments that contributed to improve the manuscript.

Appendix A. Datasets from the English Channel/European Atlantic coast used for species assignments. Location of the different areas is shown on Figure 2. TOC: total organic carbon, LOI: loss of ignition.