Food web attributes to assess estuarine benthic ecosystem

Abstract

Marine ecosystems need rapid and high-performance tools to assess biodiversity and ecosystem functioning. Descriptor 4 - food webs (MSFD) is the most functionally oriented, but challenging to implement due to limited knowledge of benthic interactions. This study investigates how spatially and temporally regulated abiotic factors shape benthic food webs by analyzing natural isotope ratios (δ13C and δ15N) and constructing 12 food web topologies at three sites (Navigator, Gambia, Tróia) in the Sado estuary over two years. Isotopic metrics, integrated with univariate and multivariate analyses, identified food web indicators sensitive to environmental variations. Spatial variability was concomitant to organic matter quality, with simpler food webs in high organic load sites (Navigator, Gambia) and complex structures in the protected site (Tróia). Temporal variability was less evident but detectable. These findings highlight the effectiveness of isotopic metrics in assessing food web complexity and contribute to MSFD D4 implementation in estuarine ecosystems.