DOI: 10.5061/dryad.pzgmsbcwr
title: Data from: Habitat dimensionality, temperature and feeding strategies as determinants of trophic structure in a marine food web

description: Disentangling the determinants of trophic structure is central to ecology.
 The capacity to capture subjugate and consume a prey (i.e. gape
 limitation) is a relevant limitation to acquire energy for most organisms,
 especially those in smaller size ranges. This generates a size hierarchy
 of trophic positions in which large organisms consume small ones. Body
 size is tightly correlated to gape limitation and explains a large
 fraction of variance in the body size-trophic position relationship.
 However, a considerable fraction of variance still remains to be
 explained. Consumer search space dimensionality (2D or 3D) and feeding
 strategies, temperature and the size structure of primary producers can
 alter the trophic structure, but tests based on information from natural
 food webs are scarce. We generated specific predictions about the body
 size trophic position relationship and evaluated them using information
 from a subtropical South Atlantic coastal marine ecosystem: benthic realm
 (2D, rocky shore and sandy beach) and the pelagic realm (3D). We
 characterized this marine coastal food web based on stable isotopes of
 carbon and nitrogen from 256 samples from primary producers (macroalgae
 and phytoplankton) to large predators (sand shark) in summer and winter.
 Consumer body size encompassed 6 orders of magnitude in weight from
 10-2 to 6x104 g. Isotopic signal corresponded to an
 integration of carbon sources from basal consumers to top predators. The
 body size-trophic position relationship showed a linear positive
 association with different slopes for the benthic and pelagic
 environments. This implies a smaller predator prey size ratio for pelagic
 (3D) with respect to benthic consumers (2D) as theoretically expected. No
 seasonal differences were found in slopes and most of the overall variance
 in benthic environments was largely explained by feeding strategies of the
 different taxonomic groups. We provide an integrated evaluation on the
 role of body size, consumer search space and feeding strategy to
 understand the determinants of trophic position. Results demonstrate that
 integrating Gape Limitation hypothesis, the dimensionality of consumer
 search space and feeding strategies into a formal robust framework to
 understand trophic structure is feasible even in complex natural
 ecosystems.
description: Study area and field collections
 Samples were collected from Punta del Diablo, a coastal marine
 ecosystem on the South Atlantic coast of Uruguay (33°54’S - 53°30’W and
 34°02’S – 53°32’W). Two surveys were conducted: one during austral summer
 (12<sup>th</sup> February) and a second one in winter
 (14<sup>th</sup> September) of 2015, at five sampling stations
 in both pelagic and benthic realms. Biological samples were collected with
 multiple gears to capture different size groups and to perform stable
 isotope analyses (SIA). Laboratory
 analysis Samples were analyzed at the Center
 for Stable Isotopes, University of New Mexico, USA (https://csi.unm.edu/).
 Carbon (δ<sup>13</sup>C) and nitrogen
 (δ<sup>15</sup>N) isotope ratios were measured by Elemental
 Analyzer Continuous Flow Isotope Ratio Mass Spectrometry using a Costech
 ECS 4010 Elemental Analyzer coupled to a ThermoFisher Scientific Delta V
 Advantage mass spectrometer via a CONFLO IV interface.
 Detailed descriptions of the methodologies for SIA analysis, the
 study area, and the associated data analysis are available in Leoni et al.
 (2024), Journal of Animal Ecology.
description: --- **Title of Dataset** Data from: Habitat dimensionality, temperature
 and feeding strategies as determinants of trophic structure in a marine
 food web Corresponding author: Angel Manuel Segura
 ([asegura@cure.edu.uy](mailto:asegura@cure.edu.uy)) This dataset
 encompasses Carbon (δ¹³C) and Nitrogen (δ¹⁵N) isotopic values obtained
 from various organisms and species during two surveys in 2015, conducted
 during the austral summer and winter, and covering both benthic and
 pelagic zones in the coastal area of Punta del Diablo (Uruguay), situated
 in the subtropical convergence of the Southwestern Atlantic Ocean. ---
 **Description of Dataset** File count: 1 File size: 8.3 KB File format:
 .csv File name: stable_isotope_data_punta_del_diablo_2015.csv Provides a
 concise summary of isotopic values from: \- Pelagic Particulate Organic
 Matter (POM), serving as a proxy for phytoplankton \- Composite
 Zooplankton \- 32 Species of Macroinvertebrates from rocky shores,
 sublittoral zones, and sandy habitats \- 19 Species of Fishes Carbon and
 nitrogen isotope values are reported using the standard delta notation
 relative to Vienna Pee Dee Belemnite (V-PDB) and to V-AIR, respectively ,
 and expressed as deviations regarding that standard, in parts per mile in
 a delta notation (δ ‰). --- **Description of features/column header for
 the Dataset** `date`: The specific date when the data was collected,
 formatted as YYYY-MM-DD. `year`: The year of data collection, all values
 are from the year 2015. `month`: The month in which the data was
 collected, "February" or "September". `season`: The
 season during which the data collection occurred, categorized as
 "Summer" or "Winter." `country`: The country where the
 data was collected, "Uruguay". `locality`: The specific locality
 or site within the country where the data collection took place,
 "Punta del Diablo". `scientific_name`: The taxonomic
 identification of the species that was subjected to stable isotope
 analysis (SIA). `life_stage`: The life stage of the specie, categorized as
 "A" for adults or "J" for juveniles. `count`: The
 number of individuals used for each species to perform SIA. `mean_d15N`:
 The mean value of nitrogen isotope (δ¹⁵N), expressed in parts per thousand
 (‰). `sd_d15N`: The standard deviation of δ¹⁵N. `mean_d13C`: The mean
 value of carbon isotope (δ¹³C), expressed in parts per thousand (‰).
 `sd_d13C`: The standard deviation of δ¹³C. `mean_mass`: The mean body
 size, expressed as wet weight in grams. `sd_mass`: The standard deviation
 of the body size. --- **Any Empty Value in the Data** Any cells containing
 'NA' or left empty represent missing (null) values. ---
 **Sharing/Access information** This is the only publicly accessible
 locations of the dataset.