stability of strong species interactions resist the synergistic effects of local and global pollution in kelp forests稳定强大的物种相互作用抵制当地的协同效应和全球污染海带森林.pdf

Stability of Strong Species Interactions Resist the Synergistic Effects of Local and Global Pollution in Kelp Forests Laura J. Falkenberg, Bayden D. Russell, Sean D. Connell* Southern Seas Ecology Laboratories, School of Earth and Environmental Sciences, University of Adelaide, South Australia, Australia Abstract Foundation species, such as kelp, exert disproportionately strong community effects and persist, in part, by dominating taxa that inhibit their regeneration. Human activities which benefit their competitors, however, may reduce stability of communities, increasing the probability of phase-shifts. We tested whether a foundation species (kelp) would continue to inhibit a key competitor (turf-forming algae) under moderately increased local (nutrient) and near-future forecasted global pollution (CO2). Our results reveal that in the absence of kelp, local and global pollutants combined to cause the greatest cover and mass of turfs, a synergistic response whereby turfs increased more than would be predicted by adding the independent effects of treatments (kelp absence, elevated nutrients, forecasted CO2). The positive effects of nutrient and CO2 enrichment on turfs were, however, inhibited by the presence of kelp, indicating the competitive effect of kelp was stronger than synergistic effects of moderate enrichment of local and global pollutants. Quantification of physicochemical parameters within experimental mesocosms suggests turf inhibition was likely due to an effect of kelp on physical (i.e. shading) rather than chemical conditions. Such results indicate that while forecasted climates may increase the probability of phase-shifts, maintenance of intact populations of foundation species could enable the continued strength of interactions and persistence of c