The influence of a large SW Atlantic shelf-break frontal system on epibenthic community composition, trophic guilds, and diversity

MAUNA, CECILIA; M. E. ACHA; LASTA, M; IRIBARNE, O

JOURNAL OF SEA RESEARCH

ELSEVIER SCIENCE BV

Lugar: AMSTERDAM; Año: 2011 vol. 66 p. 39 - 46

1385-1101

Productivity gradients (i.e., through bottom-up control) have an important influence on variability in species 23 diversity and community composition in marine systems. At the SW Atlantic shelf-break front (SBF), we 24 hypothesized that a high and stable food supply in areas under the core of a frontal influence (F) promotes a 25 Different benthic community structure (i.e., species diversity, taxa biomasses, and composition of feeding 26 guilds) than in areas located under marginal influences of the front (M). In 2007, we sampled 34 trawling 27 stations located across the SBF to evaluate this hypothesis.We compared epibenthic community composition, 28 diversity indices, and species and trophic guild biomass in F and M areas. We observed differences in 29 community composition, predator biomass, and the biomass of some taxa. However, we did not detect any 30 changes in diversity indices, suspension feeder biomass, or grazer-omnivore biomass. The scallop, 31 Zygochlamys patagonica, sponges, and the brittle star, Ophiacantha vivipara, together with the sea star 32Diplasterias brandtii characterized frontal areas. Marginal areas were characterized by the Patagonian scallop, 33 Z. patagonica, the parchment worm, Chaetopterus variopedatus, the basket star, Gorgonocephalus chilensis, the 34 sea urchin, Austrocidaris canaliculata, and the sea star, Ctenodiscus australis. These shifts in taxa were not 35 always reflected in biomass differences between areas. These results demonstrate that spatial variations in 36 oceanographic structure, even over spatial scales