Manipulating communities to determine mechanisms linking diversity, drivers, and impacts

Current empirical work focuses on determining the immediate and long-term impacts of exposure to biotic and abiotic variation and associated stressors on organisms and population dynamics.  This work began with an interest in how the presence of predators impacts organisms through non-consumptive interactions and continues with projects exploring how multiple stressors interact to influence organisms, populations, and communities across multiple temporal scales.  Due to connections among isolated populations via dispersal and measurable variation in environmental parameters among sites, aquatic communities offer optimal areas to explore these issues.  Projects in these areas also have clear links to resource management via aquaculture, conservation, and restoration.  Current projects include:

Integrating non-consumptive interaction into community ecology

The ability of predators to regulate community structure has long been recognized by ecologists, but traditional views of predation have focused on the consumptive effects of predators (how much they eat) on a single prey.  Recently, however, ecologists have

increasingly recognized that the mere presence of predators can have vast impacts on a system.  We have demonstrated these effects may have been overlooked even in well-studied systems and may be a major pathway by which keystone predators influence communities.  These non-consumptive interactions may also be impacted by environmental variation such as habitat complexity.  Ongoing work in the lab exploring how factors such as predator biomass and exposure regimes impact non-consumptive interactions and influence their full importance to ecological communities. We also explore these topics via simulations and model development.  Trade-off based mathematical model we have developed demonstrate that non-consumptive interactions may have a variety of impacts on population dynamics depending on the manner in which prey reduce predation risk, and we are currently translating predator-prey interactions into a dynamic energy budget modeling context that can allow the impact of multiple factors across multiple life stages to be considered. 

Determining the short- and long- term effects of stressors on biodiversity

Predation pressure is just of one of many stressors that organisms face,and the lab is exploring how multiple stressors interact to influence organisms, populations, and communities across multiple scales. Stressors may have immediate impacts, such as changes in growth and mortality (as non-consumptive effects show), but also may shape (and minimize) responses to future stress with-in (through phenotypic plasticity) and across (through natural selection) generations. We are carrying out projects working with oysters to isolate and compare the effects of plasticity, genetic potential, and natural selection (via mortality) in order to link work on short- and intermediate- term responses of stress to patterns and impacts of functional diversity in communities.  We work with New York's Billion Oyster Project on these issues to aid in determining best protocols including stressors and population origin in captive-rearing plans.  

Related Work

Needles, L. A., Gosnell, J. S., Waltz, T. W., Wendt, D. E., and Gaines, S. D. Trophic cascades in an invaded ecosystem: Native keystone predators facilitate a dominant invader in an estuarine community. 2015. Oikos 124: 1282–1292.


Gosnell, J.S., Macfarlan, J. A.+, Shears, N.T., and Caselle, J. E. A dynamic oceanographic front drives biogeographical structure in invertebrate settlement along Santa Cruz Island, CA. Marine Ecology Progress Series 507:181-196. 

Gosnell, J.S.,  Macfarlan, J. A., and Caselle, J. Moving oceanographic boundaries explain larval recruitment.  Presentation at the 2012 California Islands Symposium.