Description: Mesopelagic organisms play a critical role in marine ecosystems, channelling energy and organic matter across food webs and serving as the primary prey for many open-ocean predators. Nevertheless, trophic pathways involving mesopelagic organisms are poorly understood and their contribution to food web structure remains difficult to assess (St. John et al., 2016). Existing data to assess mesopelagic feeding interactions and energy transfer are scattered in the literature or remain unpublished, making it difficult to locate and use such datasets. As part of the EU funded project SUMMER - Sustainable Management of Mesopelagic Resources H2020-BG-2018-2, GA: 817806) (https://summerh2020.eu/), we created MesopTroph, a georeferenced database of diet, trophic biogeochemical markers, and energy content of mesopelagic organisms and other marine taxa from the Northeast Atlantic and Mediterranean Sea, compiled from 191 published and non-published sources. MesopTroph includes seven datasets: (i) diet compositions from stomach content analysis, (ii) stable isotopes of carbon and nitrogen (δ13C and δ15N), (iii) fatty acid trophic markers (FATM), (iv) major and trace elements, (v) energy density, (vi) estimates of diet proportions, and (vii) trophic positions. The database contains information from 4918 samples, representing 51119 specimens from 499 species or genera, covering a wide range of trophic guilds and taxonomic groups. Metadata provided for each record include the location, dates and method of sample collection, taxonomic ranks (phylum, class, order, family), number and size (or size range) of sampled organisms, method/model used in data analysis, reference and DOI of the original data source. Compiled data were checked for errors, missing information, and to avoid duplicate entries, and scientific names and taxonomy were standardized.

Description: 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.

Description: Trait-based approaches that complement taxonomic-based studies have increased in popularity among the scientific community over the last decades. The collection of biological and ecological characteristics of species (i.e., traits) provides insight into species and ecosystem vulnerability to environmental and anthropogenic changes, as well as ecosystem functioning. While most of the available trait databases to date contain essential information to understand the functional diversity of a taxonomic group or functional group based on size, the FUN Azores trait database has an ecosystem-based approach that provides a comprehensive assessment of diverse fauna (meio-, macro-, and megafauna) from benthic and pelagic environments in the Azores Marine Park; including ridges, seamounts, and hydrothermal vents. We used a collaborative approach involving 30 researchers with different expertise to develop the trait database; which contains compiled data on 14 traits representing morphological, behavioral, and life history characteristics for 1210 species, across 10 phyla.