The role of Argopecten purpuratus shells structuring the soft bottom community in shallow waters of southern Peru

摘要: Abstract Accumulation of Argopecten purpuratus shells often occurs after El Nino events in shallow waters Independencia Bay (14°17′S–76°10′W; Pisco, Peru). Here we experimentally investigate the effects their shell accumulation on macrobenthos assemblages soft bottom, areas bay. A field experiment (from May 2006 to 2007), including four treatments with different coverage levels empty A. purpuratus, were randomly arranged in: (1) devoid (“Empty” treatment: experimental control), (2) 50% plot area covered haphazardly distributed over bottom (“medium” treatment), (3) 100% shells, forming a 10 cm valve layer (“full” treatment) and (4) “natural control”. We found total 124 taxa throughout experiment. Polychaetes, crustaceans mollusks most abundant groups controls”, dominated by gastropod Nassarius gayi polychaetes Prionospio peruana, Platynereis bicanaliculata Mediomastus branchiferus. The abundance individuals (N) species richness (S) higher “medium” treatment, but only one month under positive sea thermal anomalies. Similarity analysis (Bray–Curtis) showed that control”, “empty” “full” more similar among them than treatment. Multidimensional no clear association grouping samplings Jun-06, Aug-06 Nov-06. Our results also commercial crab Romaleon polyodon polyplacophora Tonicia elegans positively affected accumulations while limpet Fissurella crassa was negatively affected. study shows directly changing habitat structure or indirectly sediment characteristics, addition scallop can modify macrobenthic assemblage; however, seasonal oceanographic variability (e.g. upwelling, Nino) could have stronger controlling this system presence itself.