Cascading effects of predator diversity and omnivory in a marine food web

Abstract:

Over-harvesting, habitat loss and exotic invasions have altered predator diversity and composition in a variety of communities which is pbkp_redicted to affect other trophic levels and ecosystem functioning. We tested this hypothesis by manipulating predator identity and diversity in outdoor mesocosms that contained five species of macroalgae and a macroinvertebrate herbivore assemblage dominated by amphipods and isopods. We used five common predators including four carnivores (crabs, shrimp, blennies and killifish) and one omnivore (pinfish). Three carnivorous predators each induced a strong trophic cascade by reducing herbivore abundance and increasing algal biomass and diversity. Surprisingly, increasing predator diversity reversed these effects on macroalgae and altered algal composition, largely due to the inclusion and performance of omnivorous fish in diverse predator assemblages. Changes in predator diversity can cascade to lower trophic levels; the exact effects, however, will be difficult to pbkp_redict due to the many complex interactions that occur in diverse food webs. ©2005 Blackwell Publishing Ltd/CNRS.

Año de publicación:

2005

Keywords:

• macroalgae
• Primary production
• predator
• Food web
• Omnivory
• ecosystem functioning
• Trophic cascade
• Biodiversity

Fuente:

scopus