Trophic Level Values Research Articles

Resource utilisation and trophic niche overlap of coralline intertidal benthic amphipods: an isotopic perspective.

Benthic amphipod feeding groups are a well-established trophic classification that is mostly based on field observations and laboratory tests and are used in ecological studies to monitor the ecological state of benthic ecosystems. Globally, carbon and nitrogen stable isotope ratio investigations have provided confirmation of, and novel insights into, the trophic ecology of benthic animals, such as polychaetes. However, stable isotopic examinations of benthic amphipods have been limited. Here, we used microgram samples to compare the species-specific dietary sources, trophic positions, and isotopic niche overlap of selected benthic amphipods from the Gulf of Kachchh, Marine National Park, using elemental analyser-isotopic ratio mass spectrometry (EA-IRMS) of carbon and nitrogen. Overall, all primary carbon sources presented wide variation in the isotopic values of δ13C (6.3‰) and δ15N (greater than 13‰). Conversely, the amphipod taxa displayed relatively narrow range for δ13C (3.9‰) and wider range for δ15N (more than 10‰). The results of the Bayesian mixing model revealed that the benthic amphipods had species-specific feeding preferences. However, the predominant carbon source was organic matter in sediment which reinforced benthic pathways for energy flow for most species. According to the estimated trophic level values (1.62-3.39), these species play a significant role as primary and secondary consumers serving as crucial trophic intermediaries in the food chain, connecting the base to the top consumers. High overlapping ecological niche amongst species was detected by SIBER analysis which indicated co-existence of the benthic amphipods in their respective microhabitats. This signifies wider utilisation of resources and inter-specific feeding preferences with minimal competition amongst amphipod species.

Enrichment potential of carbon and metals through biogeochemical pools of particulate matter and organisms of the coastal and continental margin

Loads of trace metals and organic materials on the coastal and shelf waters of the Sunda Shelf from vast terrestrial input will affect the flux dynamic, especially through biogeochemical pools. The Sunda Shelf’s biogeochemical pools (i.e., the reservoirs or storage spaces for materials such as carbon and trace metals) vary from coastal to pelagic systems. In this context, such pools can represent suspended particulate matter, sediment, water column, and trophic levels or communities of organisms. We hypothesized that the enrichment of carbon and trace metals would follow the nitrogen stable isotope enrichment. Based on the hypothesis, this study has the following purposes: 1) to assess whether trace metals and δ13C enrichment follows the increase in trophic level; 2) to assess the correlation between trace metals and carbon or nitrogen stable isotope (δ13C or δ15N) enrichment; and 3) to elucidate the potential of carbon and metals flow through the biogeochemical pools. We analyzed the isotope and trace metals properties of the biogeochemical pool of seagrass, suspended particulate matter (SPM), mollusk, and fish. We compared the trophic level value of each pool, its carbon isotope, and metal concentration. The result shows that the sources of carbon for consumers (i.e., mollusks and fish) are seagrass, particulate organic matter (POM), and SPM. SPM presents a plausible reservoir of carbon and nitrogen that can be utilized by mollusks. In addition, the potential sources of carbon and nitrogen for fish could be seagrass, POM, epiphytes, SPM, or even mollusks. Carbon enrichment occurred from the primary producers to the higher trophic levels. Nonetheless, solely cadmium (Cd) and iron (Fe) demonstrated a notable adverse association with δ13C and δ15N, correspondingly. This result suggests that the dispersion of these trace metals likely aligns with the trophic level.

Food and Feeding Habits of Fishes in Brunei Bay, Malaysia

The study of the food and feeding habits of fishes is crucial in understanding their ecology. Food and feeding habits of the 30 fish species belonging to 22 families from Bukit Sari and Awat-awat of Lawas in the Bay of Brunei were studied on 11th February 2020 and 12th February 2020 respectively. Samples were collected using “Kabat” nets, casting nets, and seine nets. The dietary components of each species were studied and expressed as a percentage of numerical composition (N), percentage of weight composition (W), and percentage of frequency of occurrence (F). Diet compositions of the species were estimated using the Index of Relative Importance (%IRI) and trophic level (TROPHj). The major food and their Index of Relative Importance (%IRI) showed the highest was shrimps (64.25%) followed by crabs (11.78%), zooplankton (6.94%), fish (6.91%), algae (4.21%), plants (1.48%), mollusks (1.01%) and others below 1.0%. TROPHj value ranged from 2.0 to 4.2 and the trophic level value of 25 fish species was carnivorous, followed by 2 species (detritivorous and herbivorous) respectively, and 1 species (piscivorous). The findings of the study may offer important data for developing management plans for the region's fishing resources.

The quantitative relationship between macrobenthic carbon and organic carbon in sediments: A case study of the northern continental shelf of the South China Sea

Macrobenthos play an important role in global biogeochemical cycles and carbon energy exchange. Macrobenthic communities on continental shelves are alimented through the sedimentation of organic material. Sedimentary organic carbon is the key step for the carbon cycling within the continental shelf benthic trophic web. However, the quantitative relationship between the macrobenthos and sediments based on total organic carbon (TOC), and the trophic pathways of macrobenthos applied by stable carbon and nitrogen isotope data (δ13C and δ15N) on the continental shelf are still limited. Therefore, the continental shelf of the northern South China Sea (NSCS), with abundant macrobenthos, was chosen as the research area. In this paper, TOC, total nitrogen (TN), δ13C and δ15N of the macrobenthos and sediments, the eco-exergy (Ex), structural eco-exergy (Exst) of macrobenthos communities of the NSCS were analysed. The TOC and TN in macrobenthos varied widely between 1.05% and 71.08% and between 0.29% and 11.36%, respectively, which were much higher than those in sediments. Trophic pathways (food sources and trophic levels) were established by applying δ13C and δ15N values of the main macrobenthic species. The similar stable isotope ratios and the trophic levels of most macrobenthos (2.0–3.4) might indicate similar food compositions and living habits. Eco-exergy grades were positively correlated with the average trophic level value of macrobenthos (correlation coefficient R=0.79). The relationship between the Ex value and the weight of required sediments estimated by the average organic carbon showed a typical positive correlation (R=0.98). This establishment of quantitative relationship provides a useful method for evaluating the structural functions of the ecosystem and researching the carbon sequestration potential of the macrobenthos community.

Differential food utilization of benthic amphipods of a tropical estuary: a stable isotopic (δ13C and δ15N) investigation.

Globally, stable isotopic methods are rapidly being employed in food web studies to quantify the relative proportions of diverse primary carbon sources in an animal diet. Tropical estuarine ecosystems, one of the vital marine habitats, harbor complex food webs due to the multiplicity of habitats and resources. The complex system of inputs and exchanges of organic matter sometimes complicate identification of the carbon sources that support the higher trophic levels. To assess the primary food sources of four abundant amphipod species in the anthropogenically influenced upper Vashishti estuary, Carbon and Nitrogen stable isotopes were employed. Seasonal variations were significant for δ13C and δ15N of suspended particulate organic matter (SPOM) and also for δ13C of sediment organic matter (SOM), but not for the isotopic values of individual amphipod species. Significant variations in the δ13C and δ15N values between amphipods suggested species-specific diets. Mixing model output indicated discrepancies in seasonal variations of food preferences between species. Trophic level values of all amphipod species indicated seasonality with lower values during post-monsoon. The low δ15N values of SPOM, SOM, and amphipod species were possibly due to the anthropogenic input of nitrogen in the estuary.

Comparative trophic ecology of two sympatric guitarfishes Pseudobatos (Chondrichthyes, Rhinobatidae) from Southeast Brazil, southwestern Atlantic.

The present study compares the trophic ecology of two guitarfishes (Pseudobatos percellens and Pseudobatos horkelii) from the continental shelf of the São Paulo State, Brazil, caught by the bottom pair trawls between 2007 and 2009. These two sympatric species are under different threat categories, "Vulnerable" and "Critically Endangered," respectively, according to Brazilian agencies. Thus, any study considering trophic ecology parameters is pivotal in understanding the trophic ecology role of such species in the ecosystem. The authors analysed 500 stomachs of P. percellens and 108 of P. horkelii, quantifying with dietary indexes: numerical (%N), gravimetric (%W), frequency of occurrence (%FO) and the prey-specific index of relative importance (%PSIRI). For P. percellens and P. horkelii, 26 and 14 different prey items were found, respectively. Crustacea and Teleostei were the most important prey items for both species, indicating a specialist feeding behaviour due to their low niche amplitude. The results provide evidence related to ontogenetic dietary shift in P. percellens and individual-level diet specialization in both species. These two benthic-demersal elasmobranchs are important mesopredators (3,7 for P. percellens, and 3,5 for P. horkelii) in the study area, with high trophic-level values.

Trophic Patterns of Freshwater Fish across the Balkan Biodiversity Hotspot

Ecological information regarding trophic patterns and the inherent structure of freshwater aquatic communities is considered fundamental in ecological research. In this study, the trophic patterns of the Greek freshwater fish fauna, belonging to the Balkan biodiversity hotspot, were investigated, and comparisons of freshwater fish species feeding habits among the Greek freshwater ecoregions were performed. The analyses based on the widely used trophic level index and the available composition feeding datasets, along with the utilization of clustering methods, indicated seven major distinct trophic guilds in the Greek ecoregions. The trophic level of the studied fish species ranged from 2.0 to 4.5, thus being within the expected values for freshwater ecosystems, revealing the presence of both top predators and primary consumers. The highest trophic level values were found in the ecoregions of northern Greece. The results also exhibited considerable predominance of higher-trophic-level zooplanktivorous and insectivorous freshwater fish species in the mainland, compared to lower-trophic-level opportunist species in the island-isolated ecoregions. These results could be used for the application of ecosystem-based models and the formulation of conservation and fishery management schemes.

Observations on the trophodynamics of sawtooth barracuda,Sphyraena putnamaefrom the Bay of Bengal, northern Indian Ocean

AbstractMarine capture ofSphyraena putnamaealong western Bay of Bengal has been increasing. Owing to scarcity of information available on feeding dynamics globally, the present study was conducted using 763 individuals captured during 2017–19, to decipher trophic ecology and relationships. Of the individuals analysed, 54.8% had their stomachs either empty or with trace amounts of food, 27.3% had part-full stomachs and 18.0% had full stomachs. Stomach vacuity and fullness as well as predator–prey weight ratio varied with increase in body size, implying higher feeding intensity in large-sized fishes. Feeding activity was highest during July–November and lowest during March–April. The species is an opportunistic piscivorous pelagic predator that feeds on teleosts (>85%) and cephalopods. Sardines were the major prey, followed by whitebait, squid, bigeye scad, Indian scad, silverbellies and Indian mackerel. Diet contents were similar between sexes (82.17%); however, it varied among seasons (56.86–69.85%). Shifts in prey preferences from sardines, squid and bigeye scad to ribbonfish, shad, grunter, Indian mackerel, horse mackerel andAceteswere observed with increase in fish size, and diet varied between individuals sized <60.0 and >60.0 cm. Trophic level value was 3.51 ± 0.13 and Levin's Standardized Niche Breadth Index was 0.21. Dietary niche breadth varied across seasons and sizes, with higher values during summer and winter (0.36–0.41) and in fish measuring >45.0 cm (0.50–0.68), which implies generalized feeding behaviour. The present study represents the first detailed report on the diet ofS. putnamaeand will provide a substantial contribution to stock management through understanding of trophic interactions.

Trophic transfer and dietary exposure risk of mercury in aquatic organisms from urbanized coastal ecosystems

In this study, 26 surface seawater samples, 26 surface sediment samples and 114 organisms were collected to study the trophic transfer and dietary exposure risk of mercury (Hg) in organisms from the Jiaozhou Bay, which is a typical semi-enclosed urbanized bay. The total mercury (THg) and methylmercury (MeHg) concentrations did not exceed the threshold limits and performed as: fish > crustaceans > mollusks. The trophic level values (TLs) were less than 3 in all the groups, indicating simple structure of food chain. With the increasing δ15N value, THg and MeHg were significantly biomagnified in the mollusks and fish but not in the crustaceans. In addition, the bioaccumulation and biomagnification of MeHg were higher than inorganic mercury (IHg) in the aquatic food chain. Target hazard quotient (THQ) and provisional tolerable weekly intake (PTWI) indicated that Hg exposure via consumption of seafood from the Jiaozhou Bay did not pose significant health risks for general population. Consuming fish will face the higher health risk than crustaceans and mollusks, especially in urban regions. Moreover, the risk of MeHg caused by intaking seafood deserved more attention. Trophic transfer function (TTF) explicated the transfer of Hg in the ecosystem and higher trophic transfer efficiency of MeHg than IHg. TTF interpreted the terrestrial input of Hg should be controlled to ensure the safety of consuming seafood from the Jiaozhou Bay.

Trophic Dynamics of Calanus hyperboreus in the Pacific Arctic Ocean

AbstractThe zooplankton community composition in the Pacific Arctic Ocean depends heavily on the sea ice and hydrodynamic conditions. The calanoid copepod Calanus hyperboreus is a dominant Arctic zooplankton, but its diet sources in the Pacific Arctic are unclear. C. hyperboreus individuals were collected in the northern Chukchi Sea (NCS) and the northern‐East Siberian Sea (NESS), which display contrasting chlorophyll abundance and sea ice concentration in summer 2018. Nitrogen isotopes of individual amino acid and fatty acid compositions were measured to determine its trophic level (TL) and dominant diet. C. hyperboreus collected in the NCS had higher TL values (3.0 ± 0.2) and a relatively low proportion of C20:5(n‐3). In the NESS, C. hyperboreus had lower TL values (2.7 ± 0.2) and a larger percentage of C20:5(n‐3), suggesting a greater proportion of diatoms in its diet. Spatial TL variations of C. hyperboreus between the NCS and NESS may be caused by variations in phytoplankton composition (micro‐phytoplankton vs. nano‐ and picophytoplankton) as a result of surface seawater stratification triggered by the inflow of sea ice meltwater as well as summer Bering Sea water through the Bering Strait. These results suggest that the filter‐feeding copepod C. hyperboreus could be a useful indicator to understand trophic dynamics in zooplankton food web.

Distribution and annual committed effective dose assessment of 210Po in popular marine species at the near-shore Binh Thuan province, Vietnam

210Po concentration in thirty popular marine species (twenty five fishes, four bivalves and one crab) with different habitats, feeding types, and trophic levels at the near-shore Binh Thuan, Vietnam was analyzed using the alpha detectors. The 210Po activities were widely ranged from 3.07 ± 0.18 in a fish species (Bumpnose trevally) to 78.6 ± 5.3 Bq/kg w.w in a bivalve species (Green mussel) with the average value of 16.6 Bq/kg w.w. The results showed that the species with lower trophic level value have higher 210Po concentration. Regarding the feeding types, the 210Po concentration in the omnivorous species is about 2.9 times higher than in the carnivorous species. The species living in demersal zone accumulated a high 210Po in comparison with species living in reef-associated and pelagic-neritic zones. The calculated annual committed effective dose from 210Po due to the ingestion of seafood from demersal zone and bivalve species of the area was significant high.

Methyl mercury concentrations in seafood collected from Zhoushan Islands, Zhejiang, China, and their potential health risk for the fishing community: Capsule: Methyl mercury in seafood causes potential health risk

Seafood is an important exposure route for mercury, especially methyl mercury (MeHg). Therefore, we quantified MeHg concentrations in 69 species of seafood including fish, crustaceans and mollusks collected from Zhoushan Islands, China. MeHg concentrations ranged from <0.0020–0.2098 µg/g and did not exceed the threshold limit of 1 µg/g in all sampled species, However, MeHg concentrations significantly differed among fish species (0.0085–0.2098 mg kg−1), crustaceans (<0.002–0.0221 mg kg−1) and mollusks (<0.002–0.1389 mg kg−1). The trophic magnification factor (TMF) was determined on the basis of the trophic level (TL). The TL values for fish, crustaceans and mollusks were above 3 when the TMF values were >1. The daily dietary intake and hazard quotient for MeHg were calculated to estimate exposure and health risk through seafood consumption by local inhabitants. The calculated HQ was lower than 1, thus indicating that the exposure was below the risk threshold of related chronic diseases. However, higher MeHg concentrations in fish species such as Scoliodon sorrakowah and Auxis thazard are concerning and may pose health risk through continuous consumption by local inhabitants.

Gut content analysis confirms the feeding plasticity of a generalist fish species in a tropical river

Abstract Aim In this paper, we compared the diet composition of the South American silver croaker, Plasgioscion squamosissimus in preserved and impacted areas (agrarian land use) of an Amazonian river. Our objective was to quantify the plasticity in diet across different habitats and evaluate the importance of a carnivorous generalist species as an environmental indicator based on its feeding variation. Methods We analysed the stomach contents of 135 individuals and compared the trophic level of P. squamosissimus and the source of ingested food items in the impacted and non-impacted habitats. Results The trophic level values in both areas were similar. In both areas, P. squamosissimus used a wide variety of food items, consuming mainly fish and invertebrates of autochthonous origin. However, in terms of composition of food items, small pelagic fish and autochthonous items were more frequently consumed in the preserved area, while in the impacted area fish and benthic invertebrates were predominant in the diet. Conclusions Our gut analysis suggests plasticity in P. squamosissimus diet across varying areas, which point to the ability of P. squamosissimus to modify their diet in the impacted situation, utilizing more benthic material on impacted area in order to maintain a similar trophic position.

Trace metal trophic transference and biomagnification in a semiarid coastal lagoon impacted by agriculture and shrimp aquaculture.

We studied the biomagnification of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) with carbon (C) and nitrogen (N) stable isotope analyses during four seasons, in the food web of a semiarid coastal lagoon in the central-eastern Gulf of California (GC). The concentrations of the four metals increased among functional organism groups, from the food web base to the highest trophic levels. In general, the distribution of the elements for the four sampled seasons was Zn > Cu > Pb > Cd. The correlations between trophic level values and log-transformed metal concentrations were significantly (p < 0.05) positive for Cd (r = 0.61-0.91), Cu (r = 0.63-0.70), and Zn (r = 0.50-0.73), while Pb showed only one positive correlation (r = 0.38). The biomagnification factors (from specific predator-prey scenarios) ranged from 0.32 to 3.88 for Cd, 0.05 to 37.1 for Cu, 0.50 to 3.57 for Pb, and 0.70 to 22.2 for Zn. The trophic biomagnification factors (considering the entire food web) varied from 1.26 to 1.41 for Cd, 1.95 to 2.24 for Cu, 1.02 to 1.15 for Pb, and 1.45 to 1.78 for Zn. Our results show evidence for the biomagnification of Cd, Cu, and Zn in the studied food web, while data on Pb transference are not conclusive.

Reef fish structure assemblages in oceanic islands of the eastern tropical Pacific: Revillagigedo Archipelago and Clipperton atoll

AbstractRevillagigedo Archipelago and Clipperton atoll are oceanic islands located in the eastern tropical Pacific. The composition and trophic structure of their fish assemblages have never been characterized in detail, and the aim of this study was therefore to analyse the community structure and assess the similarity of fish assemblages between these two areas. Underwater visual fish censuses were conducted using band transects at two depth levels in three islands of the Revillagigedo Archipelago (Socorro, San Benedicto, and Roca Partida) and at Clipperton atoll. We calculated ecological indices (density, richness, Shannon diversity, Pielou evenness, and taxonomic distinctiveness) for each transect. These were compared in order to determine quantitative differences among the islands and bathymetric levels. Qualitative analyses (ANOSIM, nMDS, and SIMPER) were also performed. Finally, we analysed the trophic structure of the assemblages and the functional diversity of the four studied sites. The results showed significant differences for all indices, except diversity (H′). Roca Partida was the site with greatest abundance and richness due to the presence of pelagic species in large numbers. No significant differences were found in functional diversity, suggesting a high degree of ecological redundancy. Lower‐level carnivores with mean trophic level values of between 3.3 and 3.8 dominated both areas. The ordination analysis did not show a clear difference in fish composition among the islands, although Clipperton atoll has a particular fauna characterized by endemic species (Thalassoma robertsoni and Stegastes baldwini). In conclusion, the fish communities of the studied areas seem quite similar, but their assemblage structure differs. In particular, Clipperton is differentiated by the influence of endemic species.

Implementation of an end-to-end model of the Gulf of Lions ecosystem (NW Mediterranean Sea). I. Parameterization, calibration and evaluation

An end-to-end model named OSMOSE-GoL has been built for the Gulf of Lions, the main French Mediterranean fishing area. This spatialized dynamic model links the coupled hydrodynamic and biogeochemical model Eco3M-S/SYMPHONIE (LTL – low trophic level model) to OSMOSE (HTL – high trophic level model). It includes 15 compartments of living organisms, five from the LTL model (i.e. nanophytoplankton, microphytoplankton, nanozooplankton, microzooplankton and mesozooplankton) and ten from the HTL model (northern krill, southern shortfin squid, European pilchard, European anchovy, European sprat, Atlantic horse mackerel, Atlantic mackerel, blue whiting, European hake and Atlantic bluefin tuna). With the exception of northern krill and European sprat, all HTL species are commercially exploited and undergo fisheries mortality pressure. The modeled species represent more than 70% of annual catches in this area. This paper presents the parameterization, calibration and evaluation of this model with satellite data for phytoplankton and with biomass, landings, diet and trophic level data for HTL groups. For most species, the diets in output of OSMOSE-GoL are similar to field and literature data in terms of dominant prey groups and species. However, some differences were observed. Various reasons may explain the mismatch between the modeled diet and field data. Benthic prey sometimes observed in the stomach content of the HTL predators were not modeled in OSMOSE-GoL. Field studies were carried out at specific periods and locations, while our data concern the period 2001–2004 and the entire modeled domain. Inter- and intra-annual variations in spatial distribution and density of prey may also explain these differences. The model estimates trophic level values similar to those cited in the literature for all the HTL compartments. These values are also close to the trophic levels estimated by a previous Ecopath model for the same area and period. Even though some improvements are still possible, this model may already be of use to explore fishery or Marine Protected Areas scenarios for socio-ecosystem management issues.

Bioaccessibility and human health implications of heavy metals in different trophic level marine organisms: A case study of the South China Sea

This study investigated the total concentrations and bioaccessibility of heavy metals in edible tissues and trophic levels of 12 marine organism species in the South China Sea. The results were used to estimate health risks to humans. Of the heavy metals detected, nickel (Ni) was present at the highest concentrations, followed in descending, order by iron (Fe), zinc (Zn), manganese (Mn), chromium (Cr), copper (Cu), cadmium (Cd) and lead (Pb). Cd had the highest percentage bioaccessibility (61.91%). There were no correlations between log-transformed total metal concentrations and trophic level values, nor between log-transformed bioaccessibility metal concentrations and trophic level values. This indicates there is no biomagnification among these trace metals. The carcinogenic risk probabilities for Pb and Cr to urban and rural residents were below the acceptable level (< 1 × 10−4). The target hazard quotient (THQ) value for each metal and the total THQ values for all metals studied indicated no significant risk of non-carcinogenic effects to urban and rural residents from consuming marine organisms from the South China Sea.

Evaluation of Water Quality in Eutrophic Shallow Lakes: Case Study on Lake Uluabat, Turkey

Lake Uluabat is one of the most important shallow lakes in Turkey. The lake is located 15 km south of the Marmara Sea and 30 km west of the city of Bursa. The lake is very important in terms of biodiversity, but knowledge of its water quality is somewhat limited. The objective of this study was to assess water quality in Lake Uluabat and provide information for future management decisions. The temperature (T), pH, electrical conductivity (EC), dissolved oxygen (DO), alkalinity, chemical oxygen demand (COD), nitrogen species, phosphorus species, and chlorophyll-a (Chl-a) concentrations were monitored monthly at ten sampling points in the lake between August 2013 and July 2014. As a result, it was determined that the lake water has the characteristics of class 4 waters according to the Turkish Surface Water Quality Management Regulations (SWQMR). Also it was determined that Mustafakemalpaşa Brook carries significant amount of pollution loads into the lake. According to qualitative and quantitative observations, the effects of human impact and current status of the lake were determined. The physical and chemical characteristics of the lake water have changed according to human activities and nutrient loadings. According to the trophic level values and concentration values, the Lake exceeded the regulation limits.

Potential omnivory in the sea urchin Diadema antillarum?

Sea urchins are one of the most important herbivores of shallow-water reefs in the Western Atlantic, capable of controlling seaweed communities. One of them, Diadema antillarum Philippi, 1845 has been target of several studies due to its capacity to control algal communities, and it has been considered a generalist herbivore species. Nevertheless, the assimilation process in D. antillarum using stable isotopes remains unclear. Our main goals were to characterize isotopically the sea urchin D. antillarum with the surrounding macroalgae communities, determine its trophic position, and calculate the contribution of the primary producers using stable isotopes. We collected samples of sea urchin and their potential food resources at four shallow water reefs of Puerto Rico Archipelago during February and October of 2013. The δ13C isotopic ratio of D. antillarum did not vary on site and in time, but it varied spatial and temporally in term of δ15N. The Trophic level (TL) ranged from 2.35 ±0.11 to 3.24 ±0.17, and exhibited spatial and temporal significant differences. The lack of congruent polygons found in this study, and the high TL values support the conclusion that D. antillarum produced isotopic ratios not adequately explained by the algal data. Our findings reinforce the importance of benthic invertebrates as potential nitrogen sources for D. antillarum. Further studies including benthic invertebrates may help to quantify the contribution of those species to the diet of D. antillarum.

Santa Catalina (Lequeitio, Basque Country): An ecological and cultural insight into the nature of prehistoric fishing in Cantabrian Spain

The paper presents the fish collections retrieved in the site of Santa Catalina. The results from this analysis are explored in terms of the Richness, Diversity, Equitability and Trophic level values of the 61 archeological levels that span from the Upper Magdalenian (15kycalBC) to the Azilian (10kycalBC). These results are discussed within the frame of theoretical proposals on the origin and evolution of prehistoric fishing in the Cantabrian region, and evidence that some of these proposals appear to be in need of revision.