Grantee Research Project Results

Environmental Change and the Size Structure of Phytoplankton Communities on Ecological and Geological Timescales

EPA Grant Number: FP916323
Title: Environmental Change and the Size Structure of Phytoplankton Communities on Ecological and Geological Timescales
Investigators: Finkel, Zoe V.
Institution: Rutgers University - New Brunswick
EPA Project Officer: Lee, Sonja
Project Period: January 1, 2004 through December 31, 2006
Project Amount: $111,172
RFA: STAR Graduate Fellowships (2004) RFA Text |  Recipients Lists
Research Category: Fellowship - Oceanography , Fellowship - Aquatic Ecology and Ecosystems , Academic Fellowships

Objective:

My objective is to test the hypothesis that size-dependent physiological responses to spatial and temporal changes in the availability of resources required for phytoplankton growth can explain ecological and evolutionary changes in the size structure of phytoplankton communities and can change the efficiency of organic carbon export into the deep sea.

My research focuses on the role of phytoplankton size structure in global biogeochemical cycles. Using a combination of physiological experiments, growth models, and analyses of satellite and geological data, my work is focused on the biogeochemical consequences and the physiological strategies and environmental conditions that sustain the size structure of phytoplankton communities on different temporal and spatial scales.

Approach:

I will add or develop databases of size changes in phytoplankton communities on ecological and evolutionary scales and use a combination of physiological experiments and growth models to ask two main questions:

(1) Can size-dependent differences in physiological response to resource availability explain why large phytoplankton cells dominate communities in areas of high nutrient supply whereas small phytoplankton cells dominate in areas with low nutrient supply?

(2) Can size-dependent physiological responses to long-term changes in environmental conditions explain evolutionary changes in the size distribution of phytoplankton taxa?

The structure of phytoplankton communities is extremely important to the function of aquatic ecosystems. Large phytoplankton cells tend to be grazed by large zooplankton, resulting in shorter, simpler food webs that result in more efficient matter and energy transfer. Relatively large phytoplankton cells often dominate high productivity environments and are associated with the export of photosynthetically fixed carbon out of the surface ocean into the deep sea where a small but significant fraction of this flux is buried on the seafloor. This flux of biologically produced carbon into the deep ocean is referred to as the biological pump and is critical to the ocean’s capacity to act as a carbon sink.

This study will contribute to our understanding of how environmental change may alter the size structure of the phytoplankton communities and therefore the capacity for the ocean to act as a carbon sink. Using laboratory experiments and physiological growth models, I will investigate physiological strategies that provide cells of different sizes advantages under different environmental conditions. Using models and field data, I will investigate the physiological bases for community size structure in modern phytoplankton communities. I also will examine the relationship between geological scale environmental change and evolutionary changes in the size of marine phytoplankton. The overall goal of my work is to provide an evaluation of the role of environmental change in the regulation of the size structure of phytoplankton communities on long- and short-time scales to complement and improve our understanding of how anthropogenic climatic change may effect phytoplankton communities and the oceanic carbon sink.

Supplemental Keywords:

fellowship, climate change, oceanography, macroecology, size structure, phytoplankton,, RFA, Ecosystem Protection/Environmental Exposure & Risk, Scientific Discipline, Air, ECOSYSTEMS, Aquatic Ecosystem, Aquatic Ecosystems & Estuarine Research, Atmosphere, Oceanography, Aquatic Ecosystems, Air Pollution Effects, Biochemistry, climate change, Environmental Monitoring, marine phytoplankton, nutrient dynamics, oceanic phytoplankton, phytoplankton, ecosystem impacts, aquaculture, global climate models, anthropogenic impact, climate variability, ecosystem monitoring, ecosystem response, biogeochemcial cycling, carbon supply, climatic influence

Progress and Final Reports:

2004

2005

Final