1. Ecosystem functions such as productivity and nutrient cycling tend to be more stable and to be higher at higher levels of biodiversity, or number of species present in a locale. As biodiversity is declining in many areas of the world, we wondered how the functional consequences of diversity loss compared to other ecosystem changes such as climate change or nutrient pollution. In a meta-analysis led by Dave Hooper, Mary O’Connor and colleagues in an NCEAS working group found that biodiversity loss causes reductions in ecosystem function on par with other ecosystem stresses. [Hooper et al, Nature, 2012]. The same group published a review of evidence to date and unresolved questions in early 2011 [Cardinale et al, American Journal of Botany, 2011].
2. Effects of predation on intraspecific aggregation of prey and prey diversity in a subtidal marine food web. Zac Long, Mary O’Connor and John Bruno examined how predator presence influences prey aggregation to ultimately influence prey alpha- and beta- diversity patterns. [Long et al, JEMBE 2012].
3. Predator diversity in the ocean is changing, due to habitat change, overfishing, and other processes. Our research explores the ecological importance of predator diversity by asking the question, ‘what are the ecological effects of diverse predator assemblages?’ To test the effect of predator diversity on prey and plants, we manipulated the diversity of crab, shrimp and fish predators in a subtidal marine ecosystem. We conducted numerous experiments field cages and in outdoor mesocosms. We found that predator diversity does not strongly affect prey assemblages through mechanisms such as sampling or complementarity (O’Connor and Bruno 2009), although if omnivorous predators are included in in the predator mixture, they can dramatically alter the influence of the overall predator assemblage. Under these conditions, the herbivore and plant community are strikingly different compared to communities with no omnivorous predators (Bruno and O’Connor 2005).