DOI: 10.5061/dryad.vg16p
title: Data from: Structure and functioning of intertidal food webs along an avian flyway: a comparative approach using stable isotopes

description: Food webs and trophic dynamics of coastal systems have been the focus of
 intense research throughout the world, as they prove to be critical in
 understanding ecosystem processes and functions. However, very few studies
 have undertaken a quantitative comparison of entire food webs from a key
 consumer perspective across a broad geographical area, limiting relevant
 comparisons among systems with distinct biotic and abiotic components. We
 investigate the structure and functioning of food webs in four tidal
 ecosystems of international importance for migratory shorebirds along the
 East Atlantic Flyway: Tejo estuary in Portugal, Sidi Moussa in Morocco,
 Banc d'Arguin in Mauritania and Bijagós archipelago in Guinea-Bissau.
 Basal food sources, shorebirds and their prey (benthic invertebrates) were
 sampled in all areas, and Bayesian stable isotope mixing models and
 community-wide metrics were used in a comparative analysis among areas.
 Significant differences among study areas were found in the structure of
 food webs, as well as in the relative importance of basal resource pools
 supporting each food web. Overall, the food web of Banc d'Arguin was
 characterized by lower trophic diversity and higher functional redundancy
 than the other sites. This result might be explained by the low number of
 trophic pathways of organic matter transfer in this seagrass-dominated
 system which, as a fossil estuary, lacks inputs from both freshwater and
 nutrient-rich offshore oceanic waters. Structure of shorebird communities
 was consistent with the main organizational patterns found for each food
 web, highlighting the less diverse character of the community of Banc
 d'Arguin. At Banc d'Arguin and Bijagós archipelago, which
 displayed the smallest and largest isotopic niche widths in bird
 assemblage, respectively, mean niche overlap among species was low,
 suggesting high interspecific partitioning in resource use. Tropical
 systems typically offer comparatively lower harvestable prey biomass for
 shorebirds and might thus strengthen interspecific competition, leading to
 low niche overlap among species. Our study reveals relevant differences in
 the structure of food webs and shorebird communities in coastal areas
 along an avian flyway. While differences in trophic redundancy of food
 webs point to distinct levels of ecosystem resilience, contrasts in the
 organization of shorebird communities highlight the plasticity in the
 foraging behaviour of species inhabiting areas with distinct environmental
 conditions.
description: Carbon and Nitrogen
 Stable Isotopes of ShorebirdsCarbon and nitrogen
 stable isotopic signatures of shorebird toenails collected at four
 wintering areas: Tejo estuary (Portugal), Sidi Moussa (Morocco), Banc
 d'Arguin (Mauritania) and Bijagós archipelago
 (Guinea-Bissau)Carbon and Nitrogen
 Stable Isotopes of Trophic Web ComponentsCarbon and nitrogen
 stable isotopic signatures of components of trophic webs (bassal sources
 of organic matter, algae, vegetation, zooplankton and benthic
 macroinvertebrates) collected at four wintering areas: Tejo estuary
 (Portugal), Sidi Moussa (Morocco), Banc d'Arguin (Mauritania) and
 Bijagós archipelago (Guinea-Bissau)