Habitat structure is more important than nutrient supply in modifying mussel bed assemblage in an upwelling area of the Peruvian coast.

F. N. FIRSTATER; F. HIDALGO; B.J. LOMOVASKY; E. RAMOS; P. GAMERO,; O. IRIBARNE,

HELGOLAND MARINE RESEARCH

SPRINGER

Año: 2011 vol. 5 p. 187 - 196

1438-387X

Upwelling intensity modifies coastal primary production and influences individual traits of habitatforming species. Along the Peruvian coast, beds of the mytilid Perumytilus purpuratus provide structurally complex habitats that harbour many organisms. We predict thatin the nutrient-rich system of Central Peru, the modification of structural complexity would have stronger effects on the Perumytilus community than nutrient addition. We experimentally examined the effects of nutrient addition on the Perumytilus-dominated assemblage and we evaluated the potential effect of varying shell size on the Perumytilusdominated assemblage. Nutrient addition to  the mussel bed with slow-release fertilizers caused no changes in the total macro- and microalgal biomass and did not affect abundances or composition of the assemblage. To explore the effect of structural complexity on the Perumytilus assemblage, we manipulated mussel size with experimental bags containing small and large individuals. Predators, grazers and mobile organisms were more abundant among smaller mussels, with smaller gap volume, whereas the barnacle