Dalia C Barragán-Barrera

Andrea Luna-Acosta

Laura J May-Collado

Carlos Polo-Silva

Federico G Riet-Sapriza

Paco Bustamante

María Paula Hernández-Ávila

Natalia Vélez

Nohelia Farías-Curtidor

Susana Caballero

Foraging habits and levels of mercury in a resident population of bottlenose dolphins (Tursiops truncatus) in Bocas del Toro Archipelago, Caribbean Sea, Panama

Keywords: Tursiops truncatus, inshore form, Bocas del Toro, bioaccumulation, stable isotopes

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

Introduction

Bottlenose dolphins have a global distribution including tropical, subtropical and temperate marine waters and are opportunistic predators that inhabit a wide range of ecosystems from semi-open coastal environments to the open sea [START_REF] Reeves | Guide to Marine Mammals of the world[END_REF], in which factors such as habitat topography and prey availability are known to influence their feeding preferences and foraging strategies (e.g., [START_REF] Smolker | Sponge Carrying by Dolphins (Delphinidae, Tursiops sp.): A Foraging Specialization Involving Tool Use?[END_REF][START_REF] Allen | Fine-scale habitat selection of foraging bottlenose dolphins Tursiops truncatus near Clearwater, Florida[END_REF][START_REF] Blanco | Diet of the bottlenose dolphin (Tursiops truncatus) in the Western Mediterranean Sea[END_REF][START_REF] Ingram | Identifying critical areas and habitat preferences of bottlenose dolphins Tursiops truncatus[END_REF]Duffy-Echevarría et al., 2008;[START_REF] Allen | Why do Indo-Pacific bottlenose dolphins (Tursiops sp.) carry conch shells (Turbinella sp.) in Shark Bay, Western Australia?[END_REF]Jiménez and Alava, 2013;[START_REF] Browning | Resource partitioning among South African delphinids[END_REF][START_REF] Rossman | Individual specialization in the foraging habits of female bottlenose dolphins living in a trophically diverse and habitat rich estuary[END_REF]. Given that bottlenose dolphins are opportunistic predator and have global distribution they are considered top predators that can shape the structure of aquatic communities, particularly in coastal ecosystems [START_REF] Bowen | Role of marine mammals in aquatic ecosystems[END_REF]. Bottlenose dolphin populations around the world that inhabit coastal marine habitats consequently overlaps with human activities that results detrimental for dolphins. This is particularly concerning since coastal dolphin populations are generally small (less than 100 individuals) and show high site philopatry (e.g. [START_REF] Fruet | Remarkably low genetic diversity and strong population structure in common bottlenose dolphins (Tursiops truncatus) from coastal waters of the Southwestern Atlantic Ocean[END_REF][START_REF] Vermeulen | Demographics of the Disappearing Bottlenose Dolphin in Argentina: A Common Species on Its Way Out?[END_REF][START_REF] Barragán-Barrera | High genetic structure and low mitochondrial diversity in bottlenose dolphins of the Archipelago of Bocas del Toro, Panama: a population at risk?[END_REF][START_REF] Bayas-Rea | Genetic divergence and fine scale population structure of the common bottlenose dolphin (Tursiops truncatus, Montagu) found in the Gulf of Guayaquil, Ecuador[END_REF], which makes them more vulnerable to human activities than pelagic dolphins populations. For instance, unusual mortality events in coastal dolphins have been associated to exposure of high pollutant concentrations in the Gulf of Mexico [START_REF] Damseaux | Spatial variation in the accumulation of POPs and mercury in bottlenose dolphins of the Lower Florida Keys and the coastal Everglades (South Florida)[END_REF]. Many coastal bottlenose dolphin populations show genetic isolation and are exposed to pollutants among other threats, and given their global conservation status 'least concern', it is difficult to establish conservation strategies that can effectively mitigate human threats (e.g. [START_REF] Sellas | Mitochondrial and nuclear DNA analyses reveal fine scale geographic structure in bottlenose dolphins (Tursiops truncatus) in the Gulf of Mexico[END_REF][START_REF] Parsons | Population genetic structure of coastal bottlenose dolphins (Tursiops truncatus) in the Northern Bahamas[END_REF][START_REF] Segura | Conservation implications of the genetic and ecological distinction of Tursiops truncatus ecotypes in the Gulf of California[END_REF][START_REF] Fruet | Remarkably low genetic diversity and strong population structure in common bottlenose dolphins (Tursiops truncatus) from coastal waters of the Southwestern Atlantic Ocean[END_REF][START_REF] Vermeulen | Demographics of the Disappearing Bottlenose Dolphin in Argentina: A Common Species on Its Way Out?[END_REF][START_REF] Barragán-Barrera | High genetic structure and low mitochondrial diversity in bottlenose dolphins of the Archipelago of Bocas del Toro, Panama: a population at risk?[END_REF][START_REF] Bayas-Rea | Genetic divergence and fine scale population structure of the common bottlenose dolphin (Tursiops truncatus, Montagu) found in the Gulf of Guayaquil, Ecuador[END_REF].

Collecting information about the diet and the foraging habits of bottlenose dolphin's populations is critical to establish conservation and management plans [START_REF] Hernandez-Milian | Insights into the trophic ecology of bottlenose dolphins (Tursiops truncatus) in Irish Waters[END_REF]. The diet of dolphins has been studied primarily via stomach contents, fatty-acid and stable isotope analyses (e.g. [START_REF] Ford | Dietary specialization in two sympatric populations of killer whales (Orcinus orca) in coastal British Columbia and adjacent waters[END_REF][START_REF] Hooker | Diet of northern bottlenose whales inferred from fatty-acid and stable-isotope analyses of biopsy samples[END_REF][START_REF] Das | Marine mammals from the southern North Sea: feeding ecology data from δ 13 C and δ 15 N measurements[END_REF][START_REF] Riccialdelli | Isotopic assessment of prey and habitat preferences of a cetacean community in the southwestern South Atlantic Ocean[END_REF][START_REF] Milmann | Feeding ecology of the common bottlenose dolphin, Tursiops truncatus, in southern Brazil: analyzing its prey and the potential overlap with fisheries[END_REF]. Dietary estimation indicates that coastal bottlenose dolphins prey on cephalopods and a variety of demersal and pelagic fish [START_REF] Mead | Natural history of bottlenose dolphins along the central Atlantic coast of the United States[END_REF][START_REF] Van Waerebeek | Preliminary observations of bottlenose dolphins from the Pacific coast of South America[END_REF][START_REF] Blanco | Diet of the bottlenose dolphin (Tursiops truncatus) in the Western Mediterranean Sea[END_REF][START_REF] Gannon | Diets of coastal bottlenose dolphins from the U. S. Mid-Atlantic coast differ by habitat[END_REF][START_REF] De Pierrepont | Stomach contents of English Channel cetaceans stranded on the coast of Normandy[END_REF][START_REF] Spitz | Diet overlap between harbour porpoise and bottlenose dolphin: An argument in favour of interference competition for food?[END_REF][START_REF] Milmann | Feeding ecology of the common bottlenose dolphin, Tursiops truncatus, in southern Brazil: analyzing its prey and the potential overlap with fisheries[END_REF][START_REF] Moura | Bottlenose dolphins (Tursiops truncatus, Montagu 1821) in central-northern coast of Rio de Janeiro State, Brazil: stranding patterns and insights into feeding habits[END_REF].

However, bottlenose dolphin diet varied in relation to locations and habitats (coastaloceanic) (e.g. [START_REF] Mead | Natural history of bottlenose dolphins along the central Atlantic coast of the United States[END_REF]1995;[START_REF] Walker | The diets of modern and historic bottlenose dolphin populations reflected through stable isotopes[END_REF][START_REF] Gannon | Diets of coastal bottlenose dolphins from the U. S. Mid-Atlantic coast differ by habitat[END_REF][START_REF] Santos | Variability in the diet of bottlenose dolphin, Tursiops truncatus, in Galician waters[END_REF][START_REF] Hernandez-Milian | Insights into the trophic ecology of bottlenose dolphins (Tursiops truncatus) in Irish Waters[END_REF][START_REF] Milmann | Feeding ecology of the common bottlenose dolphin, Tursiops truncatus, in southern Brazil: analyzing its prey and the potential overlap with fisheries[END_REF], seasons [START_REF] Gannon | Diets of coastal bottlenose dolphins from the U. S. Mid-Atlantic coast differ by habitat[END_REF], sex and reproductive status (e.g. lactating femalepregnant female), and age class (juvenilesadults) (e.g. [START_REF] Blanco | Diet of the bottlenose dolphin (Tursiops truncatus) in the Western Mediterranean Sea[END_REF][START_REF] Gannon | Diets of coastal bottlenose dolphins from the U. S. Mid-Atlantic coast differ by habitat[END_REF][START_REF] Santos | Variability in the diet of bottlenose dolphin, Tursiops truncatus, in Galician waters[END_REF][START_REF] Fernández | Stable isotope analysis in two sympatric populations of bottlenose dolphins Tursiops truncatus: evidence of resource partitioning?[END_REF][START_REF] Hernandez-Milian | Insights into the trophic ecology of bottlenose dolphins (Tursiops truncatus) in Irish Waters[END_REF].

The application of stable isotope analysis (SIA) is a powerful tool that can determine habitat use, trophic position and niche width in marine mammals [START_REF] Newsome | A niche for isotopic ecology[END_REF]2010;[START_REF] Graham | Using isoscapes to trace the movements and foraging behavior of top predators in oceanic ecosystems[END_REF]. This approach allows for comparisons among tissues, individuals and species, so it has been widely used to assess the trophic ecology of marine top predators such as dolphins, killer whales, sperm whales, leopard seals, sharks, tunas, marlins and swordfish (e.g. [START_REF] Mendes | Stable carbon and nitrogen isotope ratio profiling of sperm whale teeth reveals ontogenetic movements and trophic ecology[END_REF][START_REF] Méndez-Fernandez | Foraging ecology of five toothed whale species in the Northwest Iberian Peninsula, inferred using carbon and nitrogen isotope ratios[END_REF][START_REF] Polo-Silva | Trophic inferences of blue shark (Prionace glauca) in the Mexican Pacific from stable isotope analysis in teeth[END_REF]2013;[START_REF] Bisi | Trophic relationships and habitat preferences of delphinids from the Southeastern Brazilian coast determined by carbon and nitrogen stable isotope composition[END_REF][START_REF] Loor-Andrade | Population and individual foraging patterns of two hammerhead sharks using carbon and nitrogen stable isotopes[END_REF][START_REF] Chouvelon | Chemical contaminants (trace metals, persistent organic pollutants) in albacore tuna from western Indian and south-eastern Atlantic Oceans: Trophic influence and potential as tracers of populations[END_REF][START_REF] Samarra | Intra-population variation in isotopic niche in herring-eating killer whales off Iceland[END_REF][START_REF] Botta | Isotopic niche overlap and partition among three Antarctic seals from the Western Antarctic Peninsula[END_REF][START_REF] Acosta-Pachón | Trophic interaction between striped marlin and swordfish using different timescales in waters around Baja California Sur, Mexico[END_REF].

For example, the isotopic values of carbon ( 13 C) and nitrogen ( 15 N) provide an overall insight of an organism diet as it reflects the isotopic composition of prey and foraging habitat [START_REF] Deniro | Influence of diet on the distribution of carbon isotopes in animals[END_REF][START_REF] Deniro | Influence of diet on the distribution of nitrogen isotopes in animals[END_REF][START_REF] Newsome | A niche for isotopic ecology[END_REF]2010). Due to fractionation, consumers will likely be enriched approximately by 0-1% in 13 C and 2-5% in 15 N relative to its prey [START_REF] Peterson | Stable isotopes in ecosystem studies[END_REF]. Consequently, values of  13 C provide information regarding primarily production and diet composition, whereas values of  15 N indicate trophic position. In marine top predators' less depleted values of 13 C are associated with feeding coastal areas, and more depleted 13 C values correspond to offshore areas. Likewise, high values of  15 N indicate that the consumer is positioned at high levels of the local food web [START_REF] Graham | Using isoscapes to trace the movements and foraging behavior of top predators in oceanic ecosystems[END_REF][START_REF] Newsome | Using stable isotope biogeochemistry to study marine mammal ecology[END_REF].

Top predators such as bottlenose dolphins have shown high mercury (Hg) concentrations as the result of bioaccumulation with individual age and biomagnification processes in the food webs [START_REF] Fossi | The role of large marine vertebrates in the assessment of the quality of pelagic marine ecosystems[END_REF]. Therefore, Hg can be used as ecological tracer to assess the trophic position in the food chain, since Hg variations have been associated to age, individual size, and trophic level [START_REF] Boush | Total mercury content in yellowfin and bigeye tuna[END_REF][START_REF] Power | Mercury accumulation in the fish community of a sub-Arctic lake in relation to trophic position and carbon sources[END_REF][START_REF] Cai | Bioaccumulation of mercury in pelagic fishes from the Northern Gulf of Mexico[END_REF][START_REF] Newsome | Using stable isotope biogeochemistry to study marine mammal ecology[END_REF][START_REF] Kehrig | Mercury and selenium biomagnification in a Brazilian coastal food web using nitrogen stable isotope analysis: a case study in an area under the influence of the Paraiba do Sul River plume[END_REF]2017;[START_REF] Marrugo-Negrete | Biomagnification of Mercury in Fish from Two Gold Mining-Impacted Tropical Marshes in Northern Colombia[END_REF]. Hg concentration also varies with location, depth, and distance to the shore [START_REF] Rivers | Total and organic mercury in marine fish[END_REF][START_REF] Colaco | Bioaccumulation of Hg, Cu, and Zn in the Azores triple junction hydrothermal vent fields food web[END_REF][START_REF] Choy | The influence of depth on mercury levels in pelagic fishes and their prey[END_REF], with higher Hg values found in coastal ecosystems largely due to the influence of freshwater inputs and coastal development (Strom and Graves, 2001).

The bottlenose dolphin coastal population in the Archipelago of Bocas del Toro (BDT) in

Panama is small (around 80 individuals) and shows high levels of genetic isolation [START_REF] May-Collado | The Bocas del Toro's dolphin watching industry relies on a small community of bottlenose dolphins: implications for management[END_REF][START_REF] Barragán-Barrera | High genetic structure and low mitochondrial diversity in bottlenose dolphins of the Archipelago of Bocas del Toro, Panama: a population at risk?[END_REF]. This dolphin population share a unique mitochondrial haplotype not found in other Caribbean bottlenose dolphin populations suggesting high philopatry and site fidelity [START_REF] Barragán-Barrera | High genetic structure and low mitochondrial diversity in bottlenose dolphins of the Archipelago of Bocas del Toro, Panama: a population at risk?[END_REF]. Given the high philopatry of BDT's dolphins in the Archipelago, they could be used a sentinel species to monitor the spatial and temporal contaminants trends, like Hg [START_REF] Wells | Bottlenose dolphins as marine ecosystem sentinels: developing a health monitoring system[END_REF][START_REF] Reif | Atlantic bottlenose dolphins (Tursiops truncatus) as a sentinel for exposure to mercury in humans: closing the loop[END_REF]. This element has high level of toxicity and may increase the vulnerability of marine organisms to parasites and infectious agents [START_REF] Wiener | Ecotoxicology of mercury[END_REF]. High Hg concentrations detected in tissues of dolphins (e.g. [START_REF] Leonzio | Heavy metals and selenium in stranded dolphins of the northern Tyrrhenian (NW Mediterranean)[END_REF][START_REF] Frodello | Metal concentrations in the milk and tissues of a nursing Tursiops truncatus female[END_REF][START_REF] Roditi-Elasar | Heavy metal levels in bottlenose and striped dolphins off the Mediterranean coast of Israel[END_REF][START_REF] Aubail | Use of skin and blubber tissues of small cetaceans to assess the trace element content of internal organs[END_REF]Borrel et al., 2014) have been used to monitor long-term pollution in waters around the Mediterranean Sea [START_REF] Fossi | The role of large marine vertebrates in the assessment of the quality of pelagic marine ecosystems[END_REF]Borrel et al., 2014;[START_REF] Shoham-Frider | Trace elements in striped dolphins (Stenella coeruleoalba) from the Eastern Mediterranean: A 10-years perspective[END_REF]. Although Hg negative effects have not been measured directly on individuals, declines in the Mediterranean Sea bottlenose dolphin population have been attributed to pollution, so this population has considered as 'vulnerable' by the IUCN [START_REF] Bearzi | Tursiops truncatus (Mediterranean subpopulation). The IUCN Red List of Threatened Species 2012[END_REF]. Particularly in BDT, studies on coral and sediment quality have found moderate Hg levels [START_REF] Guzmán | Contamination of coral reefs by heavy metals along the Caribbean coast of Central America (Costa Rica and Panama)[END_REF][START_REF] Guzmán | Mercury levels in coral reefs along the Caribbean coast of Central America[END_REF][START_REF] Berry | Sources and spatial distribution of heavy metals in scleractinian coral tissues and sediments from the Bocas del Toro Archipelago, Panama[END_REF]. Given the potential negative effects of Hg on the small and highly philopatric bottlenose dolphin population in BDT, the main aim of this research was to study the foraging ecology and to determine the degree of contamination in dolphins. We also aim to test the hypothesis of whether bottlenose dolphin coastal habits are reflected in their isotopic signatures and THg concentrations. In order to test this hypothesis, we aimed to achieve the following objectives: a) to measure the total Hg (THg) concentration, b) stable isotope carbon (δ 13 C values) and nitrogen (δ 15 N values) in muscle of prey fish species from BDT and the skin of bottlenose dolphins in BDT and Guajira (Colombia), and c) to compare the isotopic niche width between these dolphin populations. Assessing coastal habits and monitoring of Hg in these coastal and vulnerable bottlenose dolphins as top predators in BDT represents important precautionary measures to determine their potential risk health and to facilitate future monitoring.

Materials and Methods

Study area

The Bocas del Toro Archipelago (BDT) is located on the Northwest Caribbean coast of Panama (Fig. 1). The Archipelago is home to several marine ecosystems including, seagrass, sandy bottom, coral reef, and mangrove forest [START_REF] Guzmán | Mercury levels in coral reefs along the Caribbean coast of Central America[END_REF][START_REF] D'croz | The effect of fresh water runoff on the distribution of dissolved inorganic nutrients and plankton in the Bocas del Toro Archipelago, Caribbean Panama[END_REF]. Sections of the Archipelago seem to be influenced by open ocean conditions due to water interchange through channels between sand cays and islands [START_REF] D'croz | The effect of fresh water runoff on the distribution of dissolved inorganic nutrients and plankton in the Bocas del Toro Archipelago, Caribbean Panama[END_REF]. The inner portion of the Archipelago, the Almirante Bay, is a semi-enclosed lagoon that appears to have considerable influence by oceanic conditions via the Bocas del Drago channel, located at the northern end of the Archipelago [START_REF] Guzmán | A site description of the CARICOMP mangrove, seagrass and coral reef sites in Bocas del Toro, Panama[END_REF][START_REF] D'croz | The effect of fresh water runoff on the distribution of dissolved inorganic nutrients and plankton in the Bocas del Toro Archipelago, Caribbean Panama[END_REF][START_REF] Berry | Sources and spatial distribution of heavy metals in scleractinian coral tissues and sediments from the Bocas del Toro Archipelago, Panama[END_REF]. At the southern end of Almirante Bay, is the Bocastorito Bay (also called Dolphin Bay), which is a semi-closed lagoon surrounded by mangrove forest and is considered to be an important nursery ground for the local bottlenose dolphin population and is not influenced by oceanic waters [START_REF] May-Collado | Dolphin watching boats impact on habitat use and communication of bottlenose dolphins in Bocas del Toro, Panama during 2004[END_REF]. Southern portions of the Archipelago are influenced by oceanic conditions, via water exchange through the Crawl Cay channel (Fig. 1). The climatic conditions of the Archipelago are highly influenced in terms of rainfall, so dry and rainy seasons are not clearly defined [START_REF] Guzmán | Arrecifes coralinos de Bocas del Toro, Panamá: I. Distribución, estructura y estado de conservación de los arrecifes continentales de la Laguna de Chiriquí y la Bahía Almirante[END_REF][START_REF] D'croz | The effect of fresh water runoff on the distribution of dissolved inorganic nutrients and plankton in the Bocas del Toro Archipelago, Caribbean Panama[END_REF][START_REF] Guzmán | A site description of the CARICOMP mangrove, seagrass and coral reef sites in Bocas del Toro, Panama[END_REF].

There are two major human settlements in the region that are located in Colon Island and Almirante Bay; and other small settlements are scattered throughout the Archipelago. Colon Island and Almirante Bay are the main source of chemical and noise pollution in BDT.

Human impacts in the Archipelago include: overfishing, pollution, sedimentation, and vessel traffic [START_REF] Seemann | Assessing the ecological effects of human impacts on coral reefs in Bocas del Toro, Panama[END_REF]. During the months of high precipitation, rivers like the Changuinola River discharge large amounts of sediment to the semi-closed lagoon of Almirante Bay, which transports sediments from urban areas and banana plantations. Indeed, although mercury also has a natural origin in the Archipelago [START_REF] Guzmán | Contamination of coral reefs by heavy metals along the Caribbean coast of Central America (Costa Rica and Panama)[END_REF][START_REF] Guzmán | Mercury levels in coral reefs along the Caribbean coast of Central America[END_REF], the main industrial source is due to agricultural run-off bananas plantations and vessel traffic associated to their exportation in the Almirante Port (Berry et al., 2013).

Tissue samples collection permits

Tissue samples from fish and bottlenose dolphins from BDT were collected with permission from the Autoridad Nacional del Ambiente in Panama (ANAM; permits SC/A-11-12, SC/A-43-12, SC/A-17-14, SE/A-101-16). Methods for remote skin biopsy collection were

Dolphin skin samples collection

Skin samples from free ranging bottlenose dolphins were collected using a 0.22 caliber modified rifle PAXARMS that fire remote biopsy darts with adjustable pressure [START_REF] Krützen | A biopsy system for small cetaceans: darting success and wound healing in Tursiops spp[END_REF]. Biopsy darts were shot from an approximate distance of 7-10 m from the research boat to the dolphins [START_REF] Weller | Behavioral responses of bottlenose dolphins to remote biopsy sampling and observations of surgical biopsy wound healing[END_REF][START_REF] Krützen | A biopsy system for small cetaceans: darting success and wound healing in Tursiops spp[END_REF][START_REF] Fruet | Biopsy darting of common bottlenose dolphins (Tursiops truncatus) in southern Brazil: evaluating effectiveness, short-term responses and wound healing[END_REF]. This system allows the penetration of the dolphins epidermis leaving behind a small wound [START_REF] Tezanos-Pinto | Short-term reactions and long-term responses of bottlenose dolphins (Tursiops truncatus) to remote biopsy[END_REF], and the effect on dolphins is expected to be low because the polycarbonate body of the dart spreading the impact over a wide area reducing the risk of injury when penetrating the skin [START_REF] Krützen | A biopsy system for small cetaceans: darting success and wound healing in Tursiops spp[END_REF][START_REF] Tezanos-Pinto | Short-term reactions and long-term responses of bottlenose dolphins (Tursiops truncatus) to remote biopsy[END_REF][START_REF] Fruet | Biopsy darting of common bottlenose dolphins (Tursiops truncatus) in southern Brazil: evaluating effectiveness, short-term responses and wound healing[END_REF]. Biopsy darting is a useful methodology to sample tissue of bottlenose dolphins from BDT because these dolphins are very evasive to vessels, and this system allows to collect remote samples and identify the individuals simultaneously [START_REF] Fruet | Biopsy darting of common bottlenose dolphins (Tursiops truncatus) in southern Brazil: evaluating effectiveness, short-term responses and wound healing[END_REF].

Therefore, skin biopsies were collected only if the individual dolphin was photo-identified in order to avoid re sampling the same individual dolphin [START_REF] Krützen | A biopsy system for small cetaceans: darting success and wound healing in Tursiops spp[END_REF]. When dolphins were sighted, a skin sample, photograph, and the location of the sighting were recorded. Skin samples were preserved in alcohol 70% and stored at -20 ºC [START_REF] Amos | Long-term preservation of whale skin for DNA analysis[END_REF] for subsequent laboratory analysis.

Fish muscle samples collection

Fish samples were collected from Almirante Bay, Dolphin Bay, and one 'Outermost' area located at the southern part of the Archipelago, Cayo Coral, which is influenced by oceanic conditions [START_REF] D'croz | The effect of fresh water runoff on the distribution of dissolved inorganic nutrients and plankton in the Bocas del Toro Archipelago, Caribbean Panama[END_REF][START_REF] Guzmán | A site description of the CARICOMP mangrove, seagrass and coral reef sites in Bocas del Toro, Panama[END_REF][START_REF] Berry | Sources and spatial distribution of heavy metals in scleractinian coral tissues and sediments from the Bocas del Toro Archipelago, Panama[END_REF]. In Almirante Bay and Dolphin Bay fish traps were used to capture live fish, and samples from the 'Outermost' area were collected by local fishermen using fish nets. Captured live fish were euthanized by immersing them in ice-cold water bath (-4ºC) following [START_REF] Barker | A Guide to Acceptable Procedures and Practices for Aquaculture and Fisheries Research[END_REF] and [START_REF] Blessing | Humane killing of fishes for scientific research: a comparison of two methods[END_REF] protocols. The samples were later transported to the Bocas del Toro Smithsonian Research Station for further processing. Approximately 400 mg of dorsal white muscle was removed from each specimen and preserved in alcohol 70% and stored at -20 ºC for subsequent laboratory analyses.

DNA extraction and molecular sexing

To determine the sex for each individual dolphin for which a skin sample was collected, we extracted DNA from skin samples using the DNeasy kit (QIAGEN, Valencia, CA, USA).

Samples were sexed following the protocol proposed by [START_REF] Gilson | Deer gender determination by polymerase chain reaction: validation study and application to tissues, bloodstains and hair forensic samples from California[END_REF], conducting multiplex PCR to amplify the male-specific SRY gene and ZFY/ZFX genes of males and females as positive controls. Electrophoresis was performed to observe the bands pattern and determine the sex of each individual.

Stable Isotope analyses

Dolphin and fish tissue samples were left on a bench to let alcohol evaporated, then were homogenized, and freeze-dried. Previous to isotopic analyses, 100 mg of sample was washed with 4 ml of cyclohexane for lipids removal (De Niro and Epstein, 1978;[START_REF] Méndez-Fernandez | Foraging ecology of five toothed whale species in the Northwest Iberian Peninsula, inferred using carbon and nitrogen isotope ratios[END_REF]. The sample was maintained at constant agitation by 10 min and then centrifuged at 4,500 rpm for 5 min to discard supernatant containing lipids [START_REF] Méndez-Fernandez | Foraging ecology of five toothed whale species in the Northwest Iberian Peninsula, inferred using carbon and nitrogen isotope ratios[END_REF]. The process was repeated three times. Next the samples were dried at 45°C in an oven for 48 h. A small portion of the lipid-free sample (0.2 -0.4 mg) was weighted in a tin cup to conduct stable isotope analyses with a continuous flow mass spectrometer (ThermoScientific Delta V Advantage) coupled to an elemental analyser (Thermo Scientific Flash EA 1112).

The isotopic measurements were expressed in parts per thousand (‰), using the delta (δ) unit relative to the deviation from international standard values PeeDee Belemnite Carbonate for δ 13 C and atmospheric N2 for δ 15 N [START_REF] Méndez-Fernandez | Foraging ecology of five toothed whale species in the Northwest Iberian Peninsula, inferred using carbon and nitrogen isotope ratios[END_REF][START_REF] Marrugo-Negrete | Biomagnification of Mercury in Fish from Two Gold Mining-Impacted Tropical Marshes in Northern Colombia[END_REF]. Based on replicate measurements of internal laboratory standards, experimental precision (SD) was < 0.09 for δ 13 C and < 0.36 for δ 15 N.

Average Trophic Level Calculation

Following [START_REF] Hobson | A stable isotope (δ 13 C, δ 15 N) model for the North Water food web: implications for evaluating trophodynamics and the flow of energy and contaminants[END_REF], the trophic level (TL) for each fish species was calculated according this equation:

where 'TL Reference primary consumer' represents the trophic level of the reference primary consumer which was assumed as two (TL = 2). The 'δ 15 N Consumer' is the mean of nitrogen isotope ratio (‰) of the consumer of interest and the 'δ 15 N Reference primary consumer' 𝑻𝑳 = 𝑇𝐿 Reference primary consumer + δ15N Consumer -δ15N Reference primary consumer δ15N Enrichment between 𝑇𝐿 , represents the mean of nitrogen isotope ratio of the reference primary consumer. The 'δ 15 N Enrichment between TL' is the enrichment of δ 15 N between trophic levels, which was assumed as 3.4‰ because this value represents the most frequent δ 15 N enrichment factor in aquatic food webs [START_REF] Lavoie | Biomagnification of mercury in aquatic food webs: a worldwide meta-analysis[END_REF].

Isotopic niche width and Bayesian stable isotope mixing model

To analyze stable isotope data in the context of isotopic niche width, we adopted the metrics based in a Bayesian framework (Stable Isotope Bayesian Ellipses in R: SIBER; [START_REF] Jackson | Comparing isotopic niche widths among and within communities: SIBER -Stable Isotope Bayesian Ellipses[END_REF] to compare bottlenose dolphins in BDT and La Guajira. To test the SIBER assumption of a multivariate normal distribution for each group, the R package mvnormtest' was used [START_REF] Jarek | Package "mvnormtest[END_REF]. The area of the standard ellipse (SEAC), which is an ellipse obtained by Bayesian inference that contains 40% of the data regardless of sample size and corrected for small sample sizes, was adopted to compare niche width between groups. A Bayesian estimate of the standard ellipse and its area (SEAB) was used to test whether a group ellipse is smaller or larger than the other. The convex hull area (TA), although much more sensitive to sample size, was also employed to compare among groups and their overlap [START_REF] Layman | Can stable isotope ratios provide for community-wide measures of trophic structure?[END_REF]. All these metrics were calculated using the functions implemented in the package Stable Isotope Bayesian Ellipses (SIBER model) in R v. 3.4.3.

To estimate the proportional contribution of potential local prey sources to the bottlenose dolphin diet in BDT, we conducted a Bayesian stable isotope mixing model [START_REF] Parnell | Bayesian stable isotope mixing models[END_REF]) (MixSIAR model) using the isotopic ratios of nitrogen and carbon from dolphin's skin samples (consumer tissue) and fish muscle samples (dietary items). Only fish species with three or more specimens collected were considered in the analysis. We used as enrichment factors for δ 13 C and δ 15 N the values 1.5 ± 0.5‰ and 3 ± 0.3‰, respectively, which were calculated in a previous study by [START_REF] Fernández | Stable isotope analysis in two sympatric populations of bottlenose dolphins Tursiops truncatus: evidence of resource partitioning?[END_REF] for skin bottlenose dolphin tissue.

The Bayesian stable isotope mixing model was run with a Markov Chain Monte Carlo method (chain length 1,000,000) using the MixSIAR package in R v. 3.4.3. [START_REF] Stock | MixSIAR GUI User Manual[END_REF].

Mercury analyses

Total mercury (THg) concentrations of tissues were determined using a solid sample atomic absorption spectrometer AMA-254 (Advanced Mercury Analyser-254 from Altec©) as described in [START_REF] Bustamante | Total and organic Hg concentrations in cephalopods from the North Eastern Atlantic waters: Influence of geographical origin and feeding ecology[END_REF]. The THg determination process in this spectrometer is conducted in three phases: 1) a drying phase (10 s) at 90°c to remove water from the freezedried samples; 2) a decomposition phase (150 s) in which a heating process at 750°C is carried out to release Hg from the samples, producing Hg vapor which is transported toward the surface of a gold amalgamator; and 3) a measuring phase in which the amalgamator is heated to 800°C to release the collected Hg to the spectrophotometer, allowing Hg detection by atomic absorption. Duplicates of dried, homogenized tissue samples (ranging from 1 to 10 mg) were analyzed without a chemical pre-treatment to assess mean THg concentration and SD for each [START_REF] Aubail | Use of skin and blubber tissues of small cetaceans to assess the trace element content of internal organs[END_REF][START_REF] Angel-Romero | Mercury concentrations in wild humpback whales (Megaptera novaeangliae) sampled in the Colombian Pacific and the Antarctic Peninsula[END_REF]. Measurements were repeated at least two times until haying analytical differences below 10%. Following [START_REF] Bustamante | Total and organic Hg concentrations in cephalopods from the North Eastern Atlantic waters: Influence of geographical origin and feeding ecology[END_REF], the analytical quality of the THg measurements in the AMA-254 was controlled using blanks at the beginning of each analytical session, and running analyses of certified reference material (CRM) TORT-2 (Lobster hepatopancreas, National Research Council of Canada) at the beginning and every ten analyses. The measured concentration for the CRM was 0.264 ± 0.013 ng mg -1 (n = 50) and the recovery was thus 98%. The THg measurements were showed in ng g -1 on a dry weight basis (dw) and the detection limit was 0.059 ng.

Calculation of trophic magnification factors

Hg biomagnification was evaluated assuming a trophic chain in which bottlenose dolphins are at the top of the food chain, based on the relationship between THg concentrations with δ 15 N ratios on both dolphins and fish. We calculated the mean isotopic and THg composition and its standard deviation in skin samples of bottlenose dolphins, and in muscle samples of potential prey (11 fish species). To evaluate significant correlations between THg with δ 15 N ratios as evidence of trophic magnification, Shapiro-Wilk test of normality and Bartlett test of homogeneity of variances were used to test the assumptions of parametric tests on data. A log-transformation of THg data was used to meet these assumptions. Then, Pearson correlation was performed to assess this relationship, and linear regression analysis was conducted to quantify trophic Hg magnification [START_REF] Lavoie | Biomagnification of mercury in aquatic food webs: a worldwide meta-analysis[END_REF]. Results for statistical analyses were carried out in R v. 3.4.3. and considered significant at p-value level of < 0.05.

Trophic magnification factor (TMF) was assessed using the slope (β) of the regression of log-THg, which represents the change in THg concentration per unit change in δ 15 N through the food chain [START_REF] Fey | Does trophic level drive organic and metallic contamination in coral reef organisms?[END_REF], in the following equation:

TMF = 10 β
According this model, when TMF value is > 1 there is evidence for THg accumulation (Nfon et al., 2009). We also evaluated the 'Bioaccumulation factor' (BAF) to assess Hg accumulation between prey and dolphins, as the ratio of Hg concentration in consumer (dolphin) to the Hg concentration prey (fish) [START_REF] Arnot | A review of bioconcentration factor (BCF) and bioaccumulation factor (BAF) assessments for organic chemicals in aquatic organisms[END_REF]. This relation was also used to calculate the 'Biotransference factor' (BTF) to evaluate trophic magnification, which provides information on Hg transference from dwarf round herring (prey) in the TL = 2 to fish in the TL = 3 (according to their trophic level calculated here), and to bottlenose dolphin (consumer) as the last trophic level [START_REF] Strandberg | Concentrations, biomagnification and spatial variation of organochlorine compounds in a pelagic food web in the northern part of the Baltic Sea[END_REF]Wang, 2002;[START_REF] Barwick | Biotransference and biomagnification of selenium, copper, cadmium, zinc, arsenic and lead in a temperate seagrass ecosystem from Lake Macquarie Estuary, NSW, Australia[END_REF], as follows:

According this model, when the BTF value is > 1 there is evidence for positive biomagnification, which means Hg increases at least three trophic positions in the food web [START_REF] Strandberg | Concentrations, biomagnification and spatial variation of organochlorine compounds in a pelagic food web in the northern part of the Baltic Sea[END_REF][START_REF] Barwick | Biotransference and biomagnification of selenium, copper, cadmium, zinc, arsenic and lead in a temperate seagrass ecosystem from Lake Macquarie Estuary, NSW, Australia[END_REF][START_REF] Kehrig | Mercury and selenium biomagnification in a Brazilian coastal food web using nitrogen stable isotope analysis: a case study in an area under the influence of the Paraiba do Sul River plume[END_REF].

Risk assessment

Dolphin health risk to THg exposure via fish consumption was assessed using a Maximum

Allowable Concentration (MAC) analysis based on the reference dose (RfD, ng g -1 dw), and then a risk quotient (RQ) based on this MACRfd calculated. The RfD provides a conservative risk assessment data as it is derived from toxicity and adjusted values from the no observable 𝐵𝑇𝐹 = Hg concentration in consumer (dolphin) Hg concentration in prey (fish)

adverse effect level (NOAEL) values obtained in mammals, and therefore is generally used for assessing risk to human health from exposure to trace elements [START_REF] Hung | Risk assessment of trace elements in the stomach contents of Indo-Pacific Humpback Dolphins and Finless Porpoises in Hong Kong waters[END_REF].

MACRfd approach allows assessing the maximum Hg concentration that dolphins can tolerate in their prey without negative health effects, and RQ approach allows to assess the levels of Hg risk for dolphins [START_REF] Hung | A preliminary risk assessment of trace elements accumulated in fish to the Indo-Pacific Humpback Dolphin (Sousa chinensis) in the Northwestern waters of Hong Kong[END_REF]2006).

To calculate dolphins Hg-intake, fish Hg concentrations were converted from dry weight (dw) to wet weight (ww) using the following equation:

Cw = Cd (100 -%H),
where Cw and Cd represents dw and ww respectively, and %H is the humidity percentage which ranges around 80% for several fish species (Murray and Burt, 1969;Hislop et al., 1991;Payne et al., 1999;Alonso-Fernández and Saborido-Rey, 2012). Next and following [START_REF] Hung | A preliminary risk assessment of trace elements accumulated in fish to the Indo-Pacific Humpback Dolphin (Sousa chinensis) in the Northwestern waters of Hong Kong[END_REF]2006), dolphins Hg-intake was calculated as follows:

Hg-Intake (ng g -1 day -1 )

where CF represents Hg concentrations in all fish together (ng g -1 ww) which was calculated taking into account the contribution of each item to the dolphin diet according to SIAR model results. The IR is the ingestion rate per day reported for Atlantic bottlenose dolphins (kg day - 1 ) based on an average annual food consumption of around 2,000 kg of fish for adult dolphins [START_REF] Kastelein | Food intake and body measurements of Atlantic bottlenose dolphins (Tursiops truncatus) in captivity[END_REF]. EF is the exposure frequency per day for one year (day year -1 ), represented as 365 days assuming BDT dolphins are exposed to Hg every day for one year [START_REF] Hung | A preliminary risk assessment of trace elements accumulated in fish to the Indo-Pacific Humpback Dolphin (Sousa chinensis) in the Northwestern waters of Hong Kong[END_REF]. ED is the exposure duration (years), and assuming life-time Hg exposure, we used 45 years as estimated life-time for bottlenose dolphins [START_REF] Jefferson | Marine Mammals of the World: A Comprehensive Guide to Their Identification[END_REF]. BW represents the body weight (kg), which is 260 kg according to the weight of Atlantic bottlenose dolphin individuals that showed a mean annual food consumption of 2,000 kg [START_REF] Kastelein | Food intake and body measurements of Atlantic bottlenose dolphins (Tursiops truncatus) in captivity[END_REF]. Finally, AT is the average time (days) and represents the period in days in which dolphins are exposed to Hg during life-time.

= 𝐶𝐹 x 𝐼𝑅 x 𝐸𝐹 x 𝐸𝐷 𝐵𝑊 x 𝐴𝑇 ,
According to [START_REF] Hung | Risk assessment of trace elements in the stomach contents of Indo-Pacific Humpback Dolphins and Finless Porpoises in Hong Kong waters[END_REF], when Hg-Intake is equal to RfD, the CF is equal to MACRfD, as follows:

Thus, the RfD calculated in the previous model is used in the following equation to calculate the MACRfD, as follows:

MACRfD

To assess RQ, we integrated results of exposure and dose-response assessments, using the following equation:

Statistical comparisons

The existence of significant differences between isotope ratios (δ 13 C and δ 15 N) and THg measurements in fish among the three main locations within BDT (Almirante Bay, Dolphin Bay, and 'Outermost' area), was evaluated posteriorly using Analysis of variance (ANOVA)

and Tukey multi-comparison tests, considering significant at p-value level of < 0.05.

Similarly, significant differences at p-value level of < 0.05 in the isotopic values and THg concentration with dolphins sexes was assessed using ANOVA or Kruskal-Wallis tests separately for each element. All these statistical analyses were performed in R v.

Results

A total of 175 fish and 37 dolphin tissue samples were analyzed in this study. Figure 1 shows the locations of collection for the 37 dolphin samples. Overall, there were 18 females (16 adults, two juveniles) and 19 males (18 adults, one juvenile). A total of 21 species of fish were collected (N = 223), but only 11 species had at minimum of three sub-samples to be included in the analysis (N = 175; Table 1). Of these 11 species, only dwarf round herring (Jenkinsia lamprotaenia) was found in all sampled main locations: Almirante Bay (n = 19), Dolphin Bay (n = 15), and the 'Outermost' area (n = 16).

Mercury and stable isotope of bottlenose dolphins

The comparison of carbon and nitrogen isotopic signatures between tissue samples of dolphins revealed differences in isotopic niche between populations from BDT and La Guajira (Fig. 2). BDT dolphins showed a broader isotopic signature range than La Guajira dolphins (Fig. 2). The δ 13 C values for BDT dolphins ranged between -16.40‰ and -9.17‰ (mean = -13.11‰ ± 1.95), and the δ 15 N ranged between 5.76‰ and 12.77‰ (mean = 10.24‰ ± 1.48) (Fig. 2). In contrast, La Guajira dolphins had δ 13 C values in a shorter range, between -16.44‰ and -15.26‰ (mean = -15.71‰ ± 0.41), and the δ 15 N also had a shorter range between 10.90‰ and 14.85‰ (mean = 12.30‰ ± 1.26) (Fig. 2). Regarding THg values, BDT dolphin values ranged between 94 and 4,627 ng g -1 dw (mean = 1,637 ± 1,387 ng g -1 dw) and

La Guajira dolphin values ranged between 2,720 and 10,590 ng g -1 dw (mean = 5,526 ± 3,209 ng g -1 dw) (Fig. 3). Finally, BDT dolphins did not show significant differences in THg or isotopic signatures between males and females (Kruskal-Wallis δ 13 C H = 0.01, ANOVA δ 15 N F = 0.38, Log-THg F = 0.004, all p > 0.50), which means both sexes feed on prey of the same or similar trophic level within the Archipelago. Because dolphins move during the day around the Archipelago, and dolphin were biopsied at various times of the day, we could not assume that the site of sampling was the site where the animals foraged. Therefore, comparisons among the three main locations within BDT were rendered not informative.

The results of the Bayesian stable isotope mixing model (MixSIAR) diet estimated suggested a high mean contribution of 40% by striped parrotfish (Scarus iseri) and 24% by the dwarf round herring (J. lamprotaenia) to the diet of BDT dolphins (Fig. 4). Other prey fish species contributed to less than 4% to their diet, and the blue runner (Caranx crysos), lane snapper (Lutjanus synagris), and the northern red snapper (Lutjanus campechanus) were the third, fourth and fifth prey items that contributed to their diet (4, 3 and 3%, respectively).

Remaining fish prey species contributed to 2% to dolphins' diet (Fig. 4).

THg, δ 13 C and δ 15 N stable isotope values in fish

The results showed a wide variation of THg, δ 13 C and δ 15 N values among the fish prey collected (see Table 1). The striped parrot fish showed the lowest THg and δ 15 N values (mean = 77 ± 14 ng g -1 dw; and mean = 7.35 ± 1.59‰, respectively) while the dwarf round herring showed the lowest δ 13 C values (-16.85‰, ± 1.58). Compared to fish, the dolphins showed the highest THg concentration (mean = 1,637 ± 1,387 ng g -1 dw) as well the highest δ 15 N value (mean = 10.25‰ ± 1.48).

There were significant differences in the relationship between THg and isotopic signatures of carbon and nitrogen between locations where dwarf round herring were collected (ANOVA, δ 13 C F = 165.40, δ 15 N F = 26.98, Log-THg F = 9.58, all p < 0.05; Fig. 5B-C).

The relationship between δ 13 C and δ 15 N appears to indicate that the diet of dwarf round herring in Almirante Bay and Dolphin Bay is based on oceanic and lower trophic level food items (δ 13 C mean = -17.91‰ ± 0.42, -17.78‰ ± 0.57, respectively; δ 15 N mean = 7.90‰ ± 0.38 and 8.45‰ ± 0.44, respectively), while in 'Outermost' area it is based on coastal but higher trophic level food items (δ 13 C mean = -14.73‰ ± 0.71; δ 15 N mean = 8.88‰ ± 0.36; Fig. 5A). THg showed significant and lower values in dwarf round herring collected in Dolphin Bay in relation to 'Outermost' area and Dolphin Bay (mean = 83 ± 42 ng g -1 dw, 153 ± 58 ng g -1 dw, and 196 ± 193 ng g -1 dw, respectively; p < 0.05, Tukey's test; Fig. 5B-C).

Trophic relationship, biomagnification between dolphins, and prey and risk assessment of adverse effects

The estimated relative TL was also assessed for bottlenose dolphins and the fish species described in Table 1. We used the redtail parrotfish (Sparisoma chrysopterum, n = 2) as the reference primary consumer despite we only collected two specimens, because it showed the lowest δ 15 N values (δ 15 N = 5.45‰) due to their herbivorous habits [START_REF] Luna | Sparisoma chrysopterum (Bloch & Schneider, 1801) Redtail parrotfish[END_REF].

Bottlenose dolphins and the French grunt (Haemulon flavolineatum) showed the highest TL (3.40) while the striped parrotfish (S. iseri), the yellow fin mojarra (G. cinereus), and the dwarf round herring showed the lowest TL values (2.56, 2.79, and 2.86, respectively).

Figure 6 shows the relationship between THg with δ 15 N for bottlenose dolphins and all fish expected to form the BDT' dolphin food chain. The Pearson's correlation coefficients showed significant positive correlations between THg and δ 15 N (r = 0.54; p < 0.05), and the β coefficient from linear regression showed a magnitude of 0.60. Using this β coefficient in the TMF equation, result showed a value of 3.98 (TMF > 1).

Figure 7 represents a hypothesized trophic chain for BDT dolphins, with dolphins as top predators in the Archipelago, and potential prey located in two trophic positions (TL 2 and 3) according to the TL calculated in Table 1. The Figure 7 shows BAF values between members of the trophic chain; values higher than one, are represented by black arrows. To evaluate the biomagnification among three trophic levels (BTF), we conducted comparisons between the dwarf round herring in TL = 2 (TL = 2.86), other fish including the foureye butterflyfish (Chaetodon capistratus), the northern red snapper (L. campechanus), blue runner (C. crysos), the white grunt (Haemulon plumieri), and the French grunt (H.

flavolineatum) as TL = 3 (TL= 3.14-3.41), and dolphins as next trophic level (top predator).

The dwarf round herring was used as a reference primary consumer in this trophic chain because it is widely distributed in the Archipelago (it was present in the three main locations within BDT) and is known to be part of the diet of several pelagic fish species in the Caribbean [START_REF] Friedlander | Fisheries and life history characteristics of dwarf herring (Jenkinsia lamprotaenia) in the US Virgin Islands[END_REF]. The BTF calculated between the dwarf round herring and fish from third TL are presented in blue arrows on Figure 7; all these BTF also showed values higher than one.

Discussion

This study provides the first description of feeding ecology using stable isotopes and THg biomagnification process of bottlenose dolphins from the Archipelago of Bocas del Toro (BDT, Panama). Our results support previous findings based on genetic evidence that this bottlenose dolphin population is an 'inshore form' with significant geographical isolation [START_REF] Barragán-Barrera | High genetic structure and low mitochondrial diversity in bottlenose dolphins of the Archipelago of Bocas del Toro, Panama: a population at risk?[END_REF], and highlights the vulnerability of this population to human activities [START_REF] May-Collado | The Bocas del Toro's dolphin watching industry relies on a small community of bottlenose dolphins: implications for management[END_REF][START_REF] Sitar | Boat operators in Bocas del Toro, Panama display low levels of compliance with national whale-watching regulations[END_REF].

Stable isotope composition of bottlenose dolphins

The carbon isotope ratio (δ 13 C) is an indicator of the feeding habitat of an organism [START_REF] Newsome | A niche for isotopic ecology[END_REF]2010;[START_REF] Graham | Using isoscapes to trace the movements and foraging behavior of top predators in oceanic ecosystems[END_REF]. In BDT, the range of δ 13 C values (-16.40 to -9.17‰) indicated that bottlenose dolphins have a wide feeding niche. By contrast, dolphins in La Guajira (Colombia) showed a much narrower range of carbon values and with lower values of δ 13 C (-16.44 to -15.26‰) (Fig. 2). The differences in isotopic niche wide indicated that dolphin prey species are acquiring carbon by sources unique to each location.

La Guajira coast is characterized by considerable seasonal variation in productivity which affects prey availability, and consequently dolphin presence [START_REF] Gordon | Circulation of the Caribbean Sea[END_REF][START_REF] Müller-Karger | Pigment distribution in the Caribbean Sea: Observations from space[END_REF][START_REF] Andrade | Evidence for an Eastward Flow along the Central and South American Caribbean Coast[END_REF][START_REF] Andrade | The Guajira Upwelling System[END_REF][START_REF] Lonin | Atmospheric events disrupting coastal upwelling in the southwestern Caribbean[END_REF][START_REF] Paramo | Evidencias de desacople físico-biológico en el sistema de surgencia en La Guajira, Caribe colombiano[END_REF][START_REF] Farías-Curtidor | Range extension for the common dolphin (Delphinus sp.) to the Colombian Caribbean, with taxonomic implications from genetic barcoding analysis[END_REF][START_REF] Barragán-Barrera | Stable isotopes differentiate bottlenose dolphins off west-central Florida[END_REF].

Bottlenose dolphins in La Guajira do not appear to be resident to the area, and recent genetic findings identify them as 'worldwide distributed form [START_REF] Duarte-Fajardo | Diversidad genética del delfín nariz de botella (Tursiops truncatus) en la Guajira (Caribe colombiano)[END_REF], which do not show residency to inshore areas [START_REF] Tezanos-Pinto | A worldwide perspective on the population structure and genetic diversity of bottlenose dolphins (Tursiops truncatus) in New Zealand[END_REF].

Differences between coastal and oceanic habitat are reflected in their δ 13 C values, with higher values representing coastal habitats and lower values in oceanic habitat [START_REF] Schell | Carbon and nitrogen isotope ratios in zooplankton of the Bering, Chukchi and Beaufort Seas[END_REF][START_REF] Burton | Isotopic tracking of foraging and long-distance migration in northeastern Pacific pinnipeds[END_REF][START_REF] Das | Marine mammals from the southern North Sea: feeding ecology data from δ 13 C and δ 15 N measurements[END_REF][START_REF] Newsome | Using stable isotope biogeochemistry to study marine mammal ecology[END_REF]. The values of dolphin skin samples at La Guajira were more depleted in 13 C than those reported for the BDT dolphins, but were similar to values reported from other offshore bottlenose dolphins (e.g. [START_REF] Díaz-Gamboa | Diferenciación entre tursiones Tursiops truncatus costeros y oceánicos en el golfo de California por medio de isótopos estables de carbono y nitrógeno[END_REF][START_REF] Segura | Conservation implications of the genetic and ecological distinction of Tursiops truncatus ecotypes in the Gulf of California[END_REF]. This corroborates that dolphins at La Guajira prefer to forage in oceanic habitats, which is consistent with their genetic designation of the 'worldwide distributed form'. In contrast, the BDT bottlenose dolphins showed δ 13 C values similar to other coastal populations (e.g. [START_REF] Segura | Conservation implications of the genetic and ecological distinction of Tursiops truncatus ecotypes in the Gulf of California[END_REF][START_REF] Barragán-Barrera | Stable isotopes differentiate bottlenose dolphins off west-central Florida[END_REF], indicating that they consume prey from coastal areas. The skin stable isotope δ 13 C values also indicate that the BDT dolphins fed on prey with several carbon sources. This region consists of several productive coastal ecosystems including coral reefs, mangroves, and seagrass beds [START_REF] Guzmán | Mercury levels in coral reefs along the Caribbean coast of Central America[END_REF][START_REF] D'croz | The effect of fresh water runoff on the distribution of dissolved inorganic nutrients and plankton in the Bocas del Toro Archipelago, Caribbean Panama[END_REF][START_REF] Guzmán | A site description of the CARICOMP mangrove, seagrass and coral reef sites in Bocas del Toro, Panama[END_REF]. Coastal primary producers such as macroalgae and seagrasses show elevated δ 13 C values [START_REF] Peterson | Stable isotopes in ecosystem studies[END_REF].

Consequently, the mutton snapper (Lutjanus analis) and the yellow fin mojarra (G. cinereus), which can be found in shallow coastal ecosystem (such as coral reefs, mangroves, and seagrass beds), had the highest mean δ 13 C values (-11.84‰ and -11.85‰, respectively) [START_REF] Allen | FAO Species Catalogue. Vol. 6. Snappers of the world. An annotated and illustrated catalogue of Lutjanid species known to date[END_REF]Bussing, 1995). In contrast, the dwarf round herring, which is one of the most common and more widely distributed fish in the Archipelago, showed the lowest δ 13 C value (mean = -16.85‰). This result may be explained by their nocturnal feeding behavior, in which dwarf round herring usually inhabits inshore areas during the day [START_REF] Friedlander | Fisheries and life history characteristics of dwarf herring (Jenkinsia lamprotaenia) in the US Virgin Islands[END_REF], but feed on zooplankton during the night in offshore areas [START_REF] Radakov | Some characteristics of the schooling behavior of Jenkinsia lamprotaenia[END_REF][START_REF] Friedlander | Fisheries and life history characteristics of dwarf herring (Jenkinsia lamprotaenia) in the US Virgin Islands[END_REF]. Dwarf round herrings consume a 13 C-depleted diet, since offshore primary producers (phytoplankton) have low δ 13 C values, and consequently provide a low carbon oceanic food sources for their coastal predator such a bottlenose dolphins.

Additionally, it has been suggested that nutrient inputs via river plume can increase carbon sources within BDT [START_REF] Seemann | Assessing the ecological effects of human impacts on coral reefs in Bocas del Toro, Panama[END_REF]. A previous work showed the lowest δ 13 C isotope ratios of the particulate organic carbon in Almirante Bay (mean = -20.7‰ ± 0.5) [START_REF] Seemann | Assessing the ecological effects of human impacts on coral reefs in Bocas del Toro, Panama[END_REF], and the dwarf round herring also showed more depleted 13 C values in Almirante Bay than in Dolphin Bay and the 'Outermost' area. Since Almirante Bay is a semi-enclosed lagoon with low nutrient influence from the Changuinola River runoff, and because productive marine ecosystems in this area have been affected by human activities [START_REF] Seemann | Assessing the ecological effects of human impacts on coral reefs in Bocas del Toro, Panama[END_REF], low primary production may reflect low δ 13 C values.

The present study revealed that the dwarf round herring is one of the most important prey in the diet of BDT bottlenose dolphins despite that the Archipelago offers a broad array of potential prey. These findings agree with the stomach content of one dead female found in Dolphin Bay, while this study was conducted on July 27, 2012. The female contained a large number of unidentified sardines. Besides the dwarf round herring, the other species that more contribute to the diet of these dolphins is the striped parrotfish. The stable isotope δ 15 N indicated that the BDT bottlenose dolphins feed on prey at a low trophic level. The dwarf round herring and the striped parrotfish are species that are located at 2.86 and 2.56 trophic level, respectively. In contrast, the δ 15 N values of La Guajira bottlenose dolphins indicate that they feed on prey at a higher trophic level, suggesting their diet consist primarily of pelagic species.

The great availability of herrings in the Archipelago appears to be an important reliable food source for females and males dolphins in BDT, since no significant differences between isotopic signatures and sex were detected. This predictable prey item may explain why dolphins remain in the area, despite the intensity of interactions with dolphin-watching boats.

A study by [START_REF] Kassamali-Fox | Using Markov chains to model the impacts of the dolphin watching industry on the dolphin community of Dolphin Bay, Bocas del Toro[END_REF] found that boats affected the dolphin foraging and social behavior, by switching to avoidance behaviors. The number of boats during interacting predicted the likelihood of these dolphins to return to these behaviors. However, given the availability of herring in the area and despite the presence of vessels, it is likely that dolphins are able to forage on their favorite prey.

Hg concentrations

The BDT dolphins showed lower concentrations of THg in comparison to the dolphins at La Guajira and other bottlenose dolphin populations, such as the Indian River Lagoon and the Everglades in Florida, USA (THg mean = 7,000 and THg mean = 9,314 ng g -1 dw, respectively) [START_REF] Stavros | Trace element concentrations in skin of free-ranging bottlenose dolphins (Tursiops truncatus) from the southeast Atlantic coast[END_REF][START_REF] Damseaux | Spatial variation in the accumulation of POPs and mercury in bottlenose dolphins of the Lower Florida Keys and the coastal Everglades (South Florida)[END_REF], and the Mediterranean Sea (THg = 5,700 ng g -1 dw) [START_REF] Aubail | Use of skin and blubber tissues of small cetaceans to assess the trace element content of internal organs[END_REF], where also other delphinid species show higher THg concentrations in their skin (e.g. Striped dolphin, Stenella coeruleoalba, THg mean = 3,000 ng g -1 dw; [START_REF] Aubail | Use of skin and blubber tissues of small cetaceans to assess the trace element content of internal organs[END_REF]. Nevertheless, THg levels reported here were similar to concentrations reported for bottlenose dolphins in Charleston in South Carolina, USA (THg mean = 1,700 ng g -1 dw) [START_REF] Stavros | Trace element concentrations in skin of free-ranging bottlenose dolphins (Tursiops truncatus) from the southeast Atlantic coast[END_REF], and for other delphinid species in the Mediterranean Sea (e.g. Common dolphin, Delphinus delphis, THg mean = 1,700 ng g -1 dw;

Harbour porpoise, Phocoena phocoena, THg mean = 1,600 ng g -1 dw; [START_REF] Aubail | Use of skin and blubber tissues of small cetaceans to assess the trace element content of internal organs[END_REF] and in Sub-Antarctic waters (e.g. Commerson's dolphin, Cephalorhynchus commersonii, THg mean = 1,380 ng g -1 dw; Cáceres-Saez et al., 2015) (see Table 3). Many coastal areas are influenced by several anthropogenic activities that may increment the Hg concentrations in these marine environments and thus on dolphin's prey and subsequently in their tissues [START_REF] Evans | Mercury in Florida Bay fish: spatial distribution of elevated concentrations and possible linkages to everglades restoration[END_REF]. However, the influence of prey may not be necessarily a reflection of the level of anthropogenic contamination, but differences in prey sources. For example, pelagic fish Hg concentrations have been shown to increase with increasing median depth of occurrence [START_REF] Monteiro | Mercury concentrations in prey fish indicate enhanced bioaccumulation in mesopelagic environments[END_REF][START_REF] Choy | The influence of depth on mercury levels in pelagic fishes and their prey[END_REF], so pelagic prey can reflect higher Hg concentrations than none polluted coastal areas. Following this, La Guajira dolphins appear to feed on a narrow prey selection items of pelagic habits, resulting in higher concentrations of THg than the coastal bottlenose dolphins of BDT.

Dolphins in BDT feed primarily on prey at low trophic levels with low concentration of Hg.

The Hg low concentrations could be also related to the dominance of juvenile fish in the Archipelago, which reflect lower Hg concentrations compare to bigger ones as a consequence of bioaccumulation of Hg with age [START_REF] Boush | Total mercury content in yellowfin and bigeye tuna[END_REF][START_REF] Marrugo-Negrete | Biomagnification of Mercury in Fish from Two Gold Mining-Impacted Tropical Marshes in Northern Colombia[END_REF]. The abundance of juvenile fish in areas such as Almirante Bay is a result of dramatic decrease of larger predatory fish due to overfishing [START_REF] Seemann | Assessing the ecological effects of human impacts on coral reefs in Bocas del Toro, Panama[END_REF]. Previous works have reported Hg concentrations in corals and sediments in the Archipelago [START_REF] Guzmán | Contamination of coral reefs by heavy metals along the Caribbean coast of Central America (Costa Rica and Panama)[END_REF][START_REF] Guzmán | Mercury levels in coral reefs along the Caribbean coast of Central America[END_REF][START_REF] Berry | Sources and spatial distribution of heavy metals in scleractinian coral tissues and sediments from the Bocas del Toro Archipelago, Panama[END_REF][START_REF] Seemann | Assessing the ecological effects of human impacts on coral reefs in Bocas del Toro, Panama[END_REF]. Because of their fish diet, dolphins may be bioaccumulating and magnificating THg through their prey, as suggested by the positive significant correlation between Hg concentrations with δ 15 N. Figure 7 shows the predicted Hg biotransference from low trophic level prey to the top of the chain where dolphins have the highest THg concentrations among all collected specimens. Hg biomagnification processes have been reported in other dolphin populations, for example in the coastal waters of Brazil, the Atlantic spotted dolphin (Stenella frontalis)

and the Guiana dolphin (Sotalia guanensis) [START_REF] Kehrig | Mercury and selenium biomagnification in a Brazilian coastal food web using nitrogen stable isotope analysis: a case study in an area under the influence of the Paraiba do Sul River plume[END_REF]2017). A potential concern about Hg exposure is that it can be quickly assimilated by their diet and accumulated in dolphin tissues throughout their life [START_REF] Kehrig | Mercury and selenium biomagnification in a Brazilian coastal food web using nitrogen stable isotope analysis: a case study in an area under the influence of the Paraiba do Sul River plume[END_REF] resulting in long-term health risks for dolphins. Dolphin health can be used a proxy of the health of the marine environment and thus as a wakeup call of Hg exposure to humans [START_REF] Reif | Atlantic bottlenose dolphins (Tursiops truncatus) as a sentinel for exposure to mercury in humans: closing the loop[END_REF].

Health risk

The results from the RQ based on the MACRfD indicate there is a potential health risk for both females and males dolphins in BDT due to Hg bioaccumulation through their diet. According to [START_REF] Hung | Risk assessment of trace elements in the stomach contents of Indo-Pacific Humpback Dolphins and Finless Porpoises in Hong Kong waters[END_REF], an RQ < 1 do not represent health risk. However, our analysis resulted in a value of RQ =1, which indicates a marginal health risk [START_REF] Hung | A preliminary risk assessment of trace elements accumulated in fish to the Indo-Pacific Humpback Dolphin (Sousa chinensis) in the Northwestern waters of Hong Kong[END_REF]. Given the conservation status of this population, this result should be taken as an important factor affecting the long-term health condition of this population. As described before, dolphins in BDT show high site fidelity and Hg bioaccumulates through an animal's lifespan.

Considering this, Hg could be a major health threat for calves, taking account that reproductive females can pass Hg from their tissues during gestation and through their milk [START_REF] Frodello | Metal concentrations in the milk and tissues of a nursing Tursiops truncatus female[END_REF], exposing calves to premature mortality [START_REF] Romero | The role of metallothioneins, selenium and transfer to offspring in mercury detoxification in Franciscana dolphins (Pontoporia blainvillei)[END_REF].

Furthermore, the Archipelago and particularly Dolphin Bay, where dwarf round herring showed the highest THg concentrations, is surrounded by mangrove forest, an ecosystem that is known to retain Hg making it available as methyl-Hg in water sediments to aquatic environments [START_REF] Miskimmin | Influence of dissolved organic carbon, pH, and microbial respiration rates on mercury methylation and demethylation in lake water[END_REF][START_REF] Barkay | Effects of dissolved organic carbon and salinity on bioavailability of mercury[END_REF]Kannan et al., 1998;[START_REF] Evans | Linking Everglades restoration and enhanced freshwater flows to elevated concentrations of mercury in Florida Bay fish[END_REF][START_REF] Silva | Mercury accumulation in sediments of a mangrove ecosystem in SE Brazil[END_REF][START_REF] Bergamaschi | Tidally driven export of dissolved organic carbon, total mercury, and methylmercury from a mangrove-dominated estuary[END_REF]Dameaux et al., 2017). The high Hg concentrations in dolphins living in South Florida, for example, have been attributed to this intrinsic characteristic of the mangrove forest (Dameaux et al., 2017).

This study provides evidence that the BDT dolphin population is at risk. In addition to being genetically isolated [START_REF] Barragán-Barrera | High genetic structure and low mitochondrial diversity in bottlenose dolphins of the Archipelago of Bocas del Toro, Panama: a population at risk?[END_REF] and under significant pressure due to boat traffic (May-Collado and[START_REF] May-Collado | A comparison of bottlenose dolphin whistle in the Western Atlantic Ocean: insights on factors promoting whistle variation[END_REF][START_REF] May-Collado | Dolphin changes in whistle structure with watercraft activity depends on their behavioral state[END_REF][START_REF] May-Collado | The Bocas del Toro's dolphin watching industry relies on a small community of bottlenose dolphins: implications for management[END_REF], this dolphin population is showing signs of Hg bioaccumulation. The stable isotope analysis confirmed that this population belongs to the 'inshore form', they consume a wide selection coastal prey items, similar to what has been reported in other coastal dolphin populations (e.g. [START_REF] Segura | Conservation implications of the genetic and ecological distinction of Tursiops truncatus ecotypes in the Gulf of California[END_REF][START_REF] Barragán-Barrera | Stable isotopes differentiate bottlenose dolphins off west-central Florida[END_REF]. The majority of the dolphin coastal prey items in the BDT are at low trophic level or are juvenile stage, and thus showed low concentrations of Hg. The risk assessment, trophic magnification and biotransference models showed that the Hg magnification process could be a cause of concern. Hg accumulates fast in tissues of species of high trophic level, and once in high concentrations, it is toxic, and it may causes cancer [START_REF] Béland | Toxic compounds and health and reproductive effects in St. Lawrence beluga whales[END_REF][START_REF] Martineau | Pathology and toxicology of beluga whales from the St. Lawrence Estuary, Quebec, Canada. Past, present and future[END_REF], immunotoxicity [START_REF] Desforges | Immunotoxic effects of environmental pollutants in marine mammals[END_REF], neurotoxicity [START_REF] Krey | Assessment of neurotoxic effects of mercury in beluga whales (Delphinapterus leucas), ringed seals (Pusa hispida), and polar bears (Ursus maritimus) from the Canadian Arctic[END_REF], reduction in antibody concentration [START_REF] Reif | Atlantic bottlenose dolphins (Tursiops truncatus) as a sentinel for exposure to mercury in humans: closing the loop[END_REF], and damage on the endocrine, hematopoietic, hepatic and renal systems [START_REF] Bossart | Marine mammals as sentinel species for oceans and human health[END_REF][START_REF] Schwacke | Probabilistic risk assessment of reproductive effects of polychlorinated biphenyls on bottlenose dolphins (Tursiops truncatus) from the Southeast United States Coast[END_REF][START_REF] Correa | Assessment of mercury and selenium tissular concentrations and total mercury body burden in 6 Steller sea lion pups from the Aleutian Islands[END_REF][START_REF] Reif | Atlantic bottlenose dolphins (Tursiops truncatus) as a sentinel for exposure to mercury in humans: closing the loop[END_REF]. Given the high site fidelity of dolphin to BDT, it is likely that lactating females may be transferring Hg through their milk to their newborns, and potentially affecting the calf development and survival. Further studies are needed to continue monitoring the Hg exposure and transfer from mother to calf in this inshore dolphin population, and monitoring Hg in biota in order to provide some insights on temporal trends in BDT as well. Table 1. Stable isotope ratios (δ 13 C and δ 15 N in ‰), total mercury (THg in ng g -1 dw) concentration and trophic level (TL) of bottlenose dolphins, Tursiops truncatus, and potential prey fish species collected in Bocas del Toro, Panama.

54 Table 2. Summarized values used in the risk assessment of bottlenose dolphins (Tursiops truncatus) in Bocas del Toro, Panama based on Hung et al. calculations (2004;2006).

  approved by the Smithsonian Tropical Research Institute IACUC (Institutional Animal Care and Use Committee; permits number 2011-1125-2014-06 and 2016-0203-2019-A2 to Dr. May-Collado). In addition, we included bottlenose dolphin tissue samples collected at La Guajira, located on the northeast portion of the Caribbean coast of Colombia (Fig. 1), to conduct niche trophic comparisons between dolphin populations. The tissue samples were collected under Resolution 1177 Permit for Specimen Collection of Wildlife Biodiversity Non-Commercial Purposes of Scientific Research; authorization granted by National Authority for Environmental Licenses -ANLA in Colombia to Universidad de los Andes.

Fig. 1 .

 1 Fig. 1. Location of common bottlenose dolphins (Tursiops truncatus) sampled in Bocas del Toro, Panama and La Guajira, Colombia in the Caribbean. The map of Bocas del Toro bottom left shows the three main locations where fish were collected, including Almirante Bay (green), Dolphin Bay (blue), and the 'Outermost' area (yellow).

Fig. 2 .

 2 Fig. 2. Carbon (δ 13 C) and nitrogen (δ 15 N) isotope values (‰) for Bocas del Toro, Panama (purple) and La Guajira, Colombia (blue) bottlenose dolphins (Tursiops truncatus) representing the niche trophic widths. Solid lines indicate standard ellipses areas corrected for small sample sizes (SEAc) and the convex hull area (TA) by dotted line.

Fig. 3 .

 3 Fig. 3. Stable isotope values (‰) in relation to total mercury THg (ng g -1 dw) of bottlenose dolphins (Tursiops truncatus) in Bocas del Toro, Panama (star) and La Guajira, Colombia (square). Carbon (A, δ 13 C) and nitrogen (B, δ 15 N).

Fig. 4 .

 4 Fig. 4. Posterior estimates of bottlenose dolphins (Tursiops truncatus) diet in Bocas del Toro, Panama according to MixSIAR Bayesian stable isotope mixing model. Median diet proportions (%) of each source are: blue runner Caranx crysos (CcR, 4.4%), horse-eye jackCaranx latus (CL, 2.6%), foureye butterflyfish Chaetodon capistratus (CcP, 2.4%), yellow fin mojarra Gerres cinereus (GC, 2.6%), French grunt Haemulon flavolineatum (HF, 2.2%), white grunt Haemulon plumieri (HP, 2.4%), dwarf round herring Jenkinsia lamprotaenia (JL, 23.9%), mutton snapper Lutjanus analis (LA 2.4%), northern red snapper Lutjanus campechanus (LC, 3.3%), lane snapper Lutjanus synagris (LS, 3.3%), and striped parrotfish Scarus iseri (SI, 39.7%).

Fig. 5 .

 5 Fig. 5. Mean ± SD carbon and nitrogen isotopic signatures (‰) and THg concentrations (ng g -1 dw) of dwarf round herring from three main locations within the Bocas del Toro Archipelago, Panama (triangle: Almirante Bay, circle: Dolphin Bay, square: 'Outermost' area). In (A) is represented relationship between carbon (δ 13 C) and nitrogen (δ 15 N) stable isotope values; in (B) and (C) is represented relationship between THg with δ 13 C and δ 15 N values, respectively.

Fig. 6 .

 6 Fig. 6. Relationship between nitrogen isotopic ratio (δ 15 N in ‰), and THg concentrations (ng g -1 dw) in bottlenose dolphins (Tursiops truncatus) and 11 fish species that compose a trophic chain in Bocas del Toro, Panama.

Table 3 .

 3 Total mercury (THg) skin concentrations (ng g -1 dw) of free ranging bottlenose dolphins (Tursiops truncatus), Commerson's dolphin (Cephalorhynchus commersonii), common dolphin (Delphinus delphis), harbour porpoise (Phocoena phocoena), and striped dolphin (Stenella coeruleoalba) reported in the literature. Data are shown as sample location, sample year, sample number (n), THg mean ± standard deviation, and the study reference.

Table 2

 2 summarizes the values used into equations to calculate the risk assessment of bottlenose dolphins in BDT. The table also includes the RfD and MACRfD values calculated here. RQ analyses based on MACRfD showed a value of one (RQ = 1.00).

  assisted in the field: Shakira Quiñones-Lebrón, Mónica Gamboa-Poveda, Mónica Acosta, Ayshah Kassamali-Fox, Betzi Pérez, José Julio Casas, Lissette Trejos, Joel Sánchez, Whitney Kwiers, Evelin Mosquera, Roberto Santamaría, Julie Tomczyk, Giselle Veve, Cole Tanner, This study was supported by the Small Grant in Aid of Research from the Society for Marine Mammalogy(DCBB, 2011; 2014; MPHA, 2015). The Sciences Faculty of Universidad de los Andes provided following four Research Grants to DCBB: "Proyecto Semilla -2013-2 Call for Funding of Research Category: Master and Doctoral students,

	Ashley Sitar, Paula Chávez and Roosevelt Mesa. Samples in Bocas del Toro (Panama) were
	collected with permission from the Autoridad Nacional del Ambiente (ANAM; permits
	SC/A-11-12, SC/A-43-12, SC/A-17-14; SE/A-101-16, SE/AO-6-16). Samples in La Guajira
	(Colombia) were collected under Resolution 1177 of Marco Permit for Specimen Collection
	of Wildlife Biodiversity Non Commercial Purposes of Scientific Research. This permit was
	provided by the National Authority for Environmental Licenses (ANLA) to Universidad de
	los Andes.

Acknowledgements

We thank C. Churlaud and M. Brault-Favrou from the Plateforme Analyses Elémentaires of the LIENSs laboratory for facilitating Hg analyses, and G. Guillou from the Plateforme Analyses Isotopiques of the LIENSs laboratory for its support in the stable isotope analyses.

We thank the STRI Marine Biological Station and Panacetacea for their logistical support.

We want to thank to Gabriel Jácome, Rachel Collin, Plinio Góndola, Marlon Smith, Arcadio Castillo, Urania González, Gilberto Murray, Deyvis Gonzalez, Tanyusha Grenald, Cynthia Pena, Celia Mercado, Zurenayka Alain and Orelis Arosemana at the STRI Bocas del Toro Research Station. Special thanks to boat captains Demetrio Georget, Arnulfo Record, Christian Harris, Roger Ayala, Tomás Ayala and fishermen for their support on the smallscale surveys out of Bocas del Toro and La Guajira. We also thank to several people that