Project: Role of Environmental Fluctuation in
Ecology and Evolution
The "environment" an organism experiences is a confluence of interacting physical and chemical processes that operate at multiple scales. Spatial and temporal fluctuations in the environment elicit biological responses among individuals that result in larger scale patterns.
Thus responses of individuals and communities are likely to occur over a range of spatial and temporal scales. Historically biophysical data quality (accuracy, precision, sample rate, repeatability) has been limited by available, deployable recording technology, resulting in environmental parameters observed as mean values over relatively long temporal and spatial scales. In many cases, these sampling regimes have failed to capture environmental heterogeneity and higher period fluctuations that are biologically important. A contemporary understanding of environment is emerging in which appropriate temporal and spatial scales are used to design high resolution sample regimes while measuring organismal and community responses (genomic, proteomic, life-history).
These techniques are critical to understanding what drives loss of organisms from an environment or shifts in community composition. Our lab is developing approaches to measure fluctuations in multiple parameters at high frequencies and multiple scales. We are partnered with ecologists, molecular biologists, and engineers to map organismal responses to these biophysical stressors. Our ultimate goal is to understand how extremes and rates of fluctuation affect key physiological processes.
Project: Benthic Canopies and Near-bed Flow
One area of research in our lab focuses on how the structure and flexibility of benthic canopies affect water flow and chemical exchange at the sediment water interface. Large regions of shallow coastal habitats are composed of rough surfaces formed by benthic organisms and biogenic structures (here referred to as the canopy; e.g coral, coral rubble, seagrass, macroalgae). This canopy adds a layer of complexity to the exchange of nutrients across this interface by interacting with overlying flow, and can itself act as a sink for water column nutrients. Our interests are in understanding how these canopies influence local hydrodynamics and chemical exchange. Our approach to this problem is multifaceted. We are looking at effects of canopy structure on turbulence and nutrient uptake by whole communities. We have also broken down the community into component species, and are trying to understand how uptake is distributed among members of a community and how this distribution is influenced by hydrodynamics.
Project: Physical Processes in Invertebrate
Fertilization in free spawning invertebrates is influenced by the local hydrodynamic regime and by biomechanical characteristics of spawned gametes. We have been interested in determining the affect of hydrodynamic regime on fertilization. Our results indicate that fertilization occurs over relatively long time scales and that the location of fertilization is dependent on the hydrodynamic regime in which animals spawn. Fertilization can take place on the surface of the female when eggs are released, in eddies that form behind a spawning female, on the substrate surface, or in the water column. The relative importance of these different locations is greatly influenced by the hydrodynamic conditions under which spawning occurs. Gamete characteristics play a role in fertilization. Viscosity influences how quickly eggs are removed from a spawning female and mixed into the water column.Further, we have measured the flow conditions experienced by animals during spawning so that we can determine the relative importance of local fertilization (on the female or substrate, in the eddy) to that occurring in the water column.
Florence I. M. Thomas Ph.D
Hawai'i Institute of Marine Biology
phone: 808 236-7418
fax: 808 737-0501
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