Ecology, Evolution & Marine Biology
Research DescriptionPhysical - Biological Coupling in Aquatic Ecosystems
On a global scale, aquatic ecosystems are changing due to global warming and invasive species; water quality is being negatively affected by high loadings of nutrients and pollutants. Understanding the hydrodynamics of lakes, rivers and coastal waters is central for addressing the consequences of human activities and climate change in these systems. Our studies in lakes from the tropics to the arctic, beds of introduced plants in rivers, giant kelp forests in the coastal ocean, and coral reefs are designed develop a predictive understanding of how physical forcing affects flow and ultimately ecosystem function.
Hydrodynamic Controls on Production
Internal waves, turbulent eddies, the filamentous intrusions due to streams, ocean currents, the vortices induced by flow around kelp blades and coral all have a role on supply of nutrients to autotrophs, dissolved organic carbon to heterotrophs, and particulates to filter feeders and zooplankton. Internal waves and turbulence moderate the light supply to phytoplankton. Ongoing field experiments in temperate, tropical, and arctic lakes are determining the role of wind forcing and internal waves on turbulence production, nutrient transport and system productivity; similar studies are beginning in kelp forests and coral reefs.
Hydrodynamics and Biogeochemical Hot Spots
Biogeochemical processes rarely occur at uniform rates within ecosystems. Small areas of the system may support exceptionally high rates of key processes. If these "hot spots" are hydrologically coupled to the larger system, they can strongly influence conditions in the entire ecosystem. Vegetated areas, the sediment water interface, the littoral zone, and the air-water interface can act as critical hot spots. We are exploring the linkages between hydrodynamics and flux of green house gases in arctic lakes, persistence and biogeochemical implications of anoxia due to introduced species in the Hudson River, and fluxes from porewaters and the benthic boundary in Mono Lake, CA.
Physical Limnology and Parasitism in Aquatic Ecosystems
Parasites and pathogens present some of the most dramatic examples of population destruction, and their impact seems destined to grow with climate change, species invasions and anthropogenic disturbances. We are taking an interdisciplinary approach to study how infectious disease influences population dynamics and community interactions in planktonic systems. Planktonic organisms including aquatic parasites face a swim or sink world where they must rely on physical mixing to remain suspended in the water column and for resuspension from the sediment. These processes, by mediating encounter rates of host and parasite, may be as important to disease transmission as is the biology of the hosts and parasites. To understand the ecological impact of parasites in planktonic systems we are conducting field experiments and hydrodynamic modeling to link the physics of water motion with disease transmission and population and community ecology.