Geographic distribution of two mussel species and associated assemblages along the northern Argentinean coast

ARRIBAS, LORENA PILAR; BAGUR, MARIA; KLEIN, E.; PENCHAZSADEH, P.E; PALOMO, MARIA GABRIELA

AQUATIC BIOLOGY

INTER-RESEARCH

Lugar: Oldendorf/Luhe; Año: 2013 vol. 18 p. 91 - 103

1864-7790

Ecosystem engineers can modify habitat, creating structuralmicrohabitats. This structural complexity can affect species richness. Marineecosystem engineers are able to produce local effects in combination withenvironmental variables (e.g. to create more humid habitat during low tides).We tested the hypotheses that if there is a relationship between musselmorphology and environmental factors, mussels would be larger at warmer than atcooler locations, and in areas where 2 species of mussels overlap, size andbiomass will decrease and density will increase. At a smaller scale, wepredicted that there is a relationship between the assemblage structure and hardnessof the substratum and sediment content of a mussel bed. Using a nested design,we measured density, biomass and size of 2 species of mussels, Brachidontes rodriguezii and Perumytilus (Brachidontes) purpuratus, and diversity of species associated with mussel beds at 2 rocky intertidalsites at each of 4 shores along the northern Argentinean coast. These variableswere correlated with oceanographic conditions and local characteristics.Significant correlations were found between intertidal assemblages and localfactors. The largest specimens of B. rodriguezii and P. purpuratus were found at the warmer shores. In areas where theyoverlapped, size, biomass and density of P. purpuratus were lower, although B. rodriguezii did not change. The mean abundance of invertebratesassociated with a mussel bed showed significant differences among shores. These2 species of mytilids coexist over a small area, and although these species arevery similar in their biological and ecological function, the fauna associatedwith their matrices are very different.