The Influence of Depth on the Structure and Functioning of Benthic Communities on an Exposed Sandy Shore in the SW Atlantic

MENECHELLA AG; OSINAGA M.I.; CARCEDO M.C.; BLASINA G.E.; FIORI S. M.

XX

Conferencia; The 3rd International Electronic Conference on Diversity; 2024

Multidisciplinary Digital Publishing Institute (MDPI) and Diversity (Journal)

Environmental characteristics such as depth, turbulence, and substrate compositioninfluence the structure and dynamics of benthic communities in marine ecosystems. This studyexamines the biological descriptors ( - and -diversity, abundance, and biomass) and functionaltraits (mobility, feeding mechanism, and diet) of benthic communities across a depth gradient fromthe surf zone (SZ) to shallow subtidal zones (SSZs) on an exposed sandy shore of a small touristbeach (38°59 S, 61°18 W, Argentina). Samples were collected in spring 2018 and autumn 2019 fromthree depths (1m, 5m, and 14m) using a benthic sledge (500 m mesh size). Overall, 10,055individuals from 132 taxa were identified, with Arthropoda, Annelida, and Mollusca being the mostrepresented groups. Arthropods were the most abundant at 1m, while mollusks and annelidsdominated at 5m and 14m, respectively. The maximum abundance and biomass were recorded at14m depth (1450.54 ind/100m2, 264.72 g/100m2), while -diversity was higher at 5m depth(93±15.40). -diversity indicated high species turnover across the gradient ( SOR=0.72; SIM=0.55),especially between 1m and 14m depths. More mobile, deposit-feeding, and detritivore organismswere found at 1m, while sedentary, filter-feeding, and omnivore organisms were more abundant at5m and 14m. The results indicate that biological descriptors and functional traits differedsignificantly across depths. At 1m depth (SZ), the lowest abundance, richness, and diversitysuggested that fewer species are adapted to this area, where higher mobility is advantageous tocope with the turbulence generated by continuous wave action. At 5m and 14m (SSZ), whereenvironmental conditions are more stable, sedentary species prevail. Significant differences indiet could be related to the main food sources available in each zone. These findings suggest theexistence of distinct benthic assemblages at variable depths. The heterogeneity of the marinebenthic environment increases diversity and influences ecosystem functioning.