Fatty acid (FA) composition has increasingly been used to estimate the dietary preference of marine organisms. Specific fatty acids and fatty acid ratios serve as trophic markers (FATM) and have the potential to provide insights on the long-term dietary preference of organisms. FATM have been applied for this purpose on various zooplankton, fish and up to whales. We aim to build up a database of new and published data on fatty acid content of mesopelagic fish and their predators from the central and Northeast Atlantic, and the Mediterranean Sea, to use in FATM food web studies, investigating the importance of mesopelagic organisms as predators and prey in the marine ecosystem. Here we compiled FA content (i.e., the proportion of each FA measured in sampled tissues or in the whole body of organisms in relation to total FAs analysed) of 36 fish species or genera, 15 seabirds, five marine mammals, two cephalopods, one turtle, one jelly fish, and one shark. For each record, we included all FAs with values above 0.1% of total FAs and report the percentage values as provided in the original data source. Each data record is associated with information on the sampling location, geographic coordinates, month and year of sample collection, method of sample collection, taxonomic ranks (phylum, class, order, family), number and size (or size range) of sampled organisms, as well as the reference and DOI of the original data source, for further details on the samples analysed and/or the analytical techniques used.
Stable isotope analysis (SIA) has emerged as a valuable tool for understanding the trophic structure of the marine food web and gaining insights into trophic levels and niche. Researchers are increasingly utilizing SIA in studies focused on feeding ecology, particularly in estimating the long-term diets of meso- and bathypelagic fish. To facilitate this research, a global database of published data on stable isotopes, specifically δ13C and δ15N, of meso- and bathypelagic fish was created. The database was constructed by conducting a thorough search on Google Scholar and reviewing the references cited in the retrieved papers. The search primarily involved using popular terms such as stable isotope analysis or feeding ecology in combination with mesopelagic or bathypelagic fish. The resulting SIA database contains δ13C and δ15N values for 95 different species of meso- and bathypelagic fish, belonging to 27 families, with specimens collected between 2004 and 2015. Each entry in the database includes information on the sampling location, month and year of sample collection, taxonomic classifications (phylum, class, order, family), number of samples analyzed, as well as the reference and DOI of the original data source. This global SIA database holds significant potential as a valuable tool and data source for conducting large-scale meta-analyses.
Stomach contents analysis is a standard dietary assessment method that potentially enables quantifying diet components with high taxonomic resolution. We compiled diet compositions from stomach content analysis from 75 unique species or genera: 32 fish, 19 marine mammals, 14 elasmobranchs, 9 seabirds and one marine turtle. Data were gathered from 89 published sources that included samples collected between 1885 and 2016 throughout the central and Northeast Atlantic, and the Mediterranean Sea. When available, we reported the percentage number of individuals of a prey type as a proportion of the total number of prey items (%N), the proportion of a prey item by weight (%W), and the proportion of stomachs containing a particular prey item (i.e. percent frequency of occurrence, %F). For each data record, we also provided the sampling location, geographic coordinates, month and year of sample collection, method of sample collection, taxonomic ranks (phylum, class, order, family), number and size (or size range) of sampled organisms, as well as the reference and DOI of the original data source, for further details on the samples analysed and/or the analytical techniques used.
Mesopelagic fish collected during 3 field campaigns in 2020 were analysed for their lipid content. The sampling was conducted on 5 main locations; 2 stations in the Western Mediterranean Sea (September/October), 4 stations in the North Atlantic off the Iberian Peninsula (October), 4 stations in the Irminger Sea (July), 5 stations in the Iceland Basin (July) and 4 stations in the Northern Norwegian Sea (May). The fish were collected at distinct depth intervals, with different trawl types depending on the vessel. The database consists of 28 mesopelagic fish species belonging to 9 families and 5 genera. For each record, length and wet weight of the fish analysed is recorded with the wax ester (WE), triacylglycerol (TAG) and phospholipid (PL) values as % of total lipids (TL). Each data record is associated with information on the sampling location, geographic coordinates, month and year of sample collection, sampling gear and depth, taxonomic ranks (phylum, class, order, family), and number and replicates analysed. The lipids were extracted following Folch's extraction method (Folch et al. 1957), which was implemented on whole fish or a weighted sub-sample of a homogenized whole fish. Individual lipid classes were separated by Thin Layer Chromatography (TLC). A lipid sample was spotted onto silica-coated quartz rods, (chromarods; SES GmbH) and the lipid classes separated by development in two solvent systems: hexane/diethyl ether/acetic acid (60:17:0.2, by volume) followed by hexane/diethyl ether (96:4 vol/vol). The analysis was performed using an Iatroscan MK 5 TLC-FID analyser.