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Effects of non-native species on food webs

Research Achievements

Effects of non-native species on food webs

Trainee Jarrett Byrnes and trainer J. J. Stachowicz with a third collaborator have shown how human-caused introductions of non-native species and extinctions of native species have altered the food webs of marine systems (published in PLoS1). Most extinctions (ca. 70%) are top predators and other carnivores, while most invasions are by species from lower trophic levels -- macroplanktivores, deposit feeders, and detritivores. These opposing changes alter the shape of marine food webs from a pyramid capped by a diverse array of predators and consumers to a shorter, squatter configuration dominated by filter feeders and scavengers. The consequences of the simultaneous loss of diversity at top trophic levels and gain at lower trophic levels is largely unknown. Current research suggests that a better understanding of how such simultaneous changes in diversity can impact ecosystem function will be required to manage coastal ecosystems and forecast future changes.