THE “IDIOSYNCRATIC” EFFECT OF A “SENTINEL” SPECIES ON CONTAMINATED ROCKY INTERTIDAL COMMUNITIES: Fid-Bau Portal

THE “IDIOSYNCRATIC” EFFECT OF A “SENTINEL” SPECIES ON CONTAMINATED ROCKY INTERTIDAL COMMUNITIES

Fariña, J. M. / Castilla, J. C. / Ojeda, F. P.

Depending on their biological characteristics, some species can exert strong (idiosyncratic) effects on ecosystem process. Human impacts on biological communities are related to biodiversity declines but also with species shifts and replacements. In northern Chile, the occurrence of copper mine tailings in seawater is associated with a decrease in the number of sessile species and with rocky intertidal substrate monopolization by one sentinel species, the green ephemeral‐opportunistic algae Entermorpha compressa. In spite of these changes, several consumer species persist on the contaminated sites. In this study, we test the hypothesis that changes in benthic species dominance and composition is associated with an increase in productivity, which affects intertidal consumer abundance, biomass, and/or diversity. We compare benthic species richness, composition, and productivity as well as the abundance, diversity, and diet of consumer species on contaminated and noncontaminated sites. Our results show that changes in community structure at contaminated sites are related to increased primary productivity, the absence of birds, increased abundance of reptiles and crustaceans, and larger body sizes and biomass of some intertidal fishes. The simplified organization of contaminated communities allowed us to demonstrate the importance of species composition in determining the relationship between species richness and productivity in marine systems. The special characteristics of dominance, persistence, and productivity of Enteromorpha compressa (the sentinel species on the contaminated sites) are a clear example of the idiosyncratic effect that some species could have in biological communities.