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Grantee Research Project Results

Grantee Research Project Results

Implications of Genetic Structure in Eelgrass (Zostera marina) Populations for Ecological Processes and Habitat Restoration

EPA Grant Number: U916005
Title: Implications of Genetic Structure in Eelgrass (Zostera marina) Populations for Ecological Processes and Habitat Restoration
Investigators: Hughes, Anne R.
Institution: University of California - Davis
EPA Project Officer: Boddie, Georgette
Project Period: January 1, 2001 through January 1, 2003
Project Amount: $79,298
RFA: STAR Graduate Fellowships (2001)
Research Category: Academic Fellowships , Aquatic Ecosystems , Fellowship - Aquatic Ecology and Ecosystems

Description:

Objective:

Seagrasses and related aquatic vegetation have declined extensively in the United States and worldwide in recent years because of anthropogenic effects such as habitat degradation and reduced water quality. In light of this decline and the recognized importance of eelgrass (Zostera marina) populations to the overall health of coastal systems, there is a significant need to understand the dynamics and genetic structure of these populations. Furthermore, because of the priority of these systems for restoration and conservation projects, research examining the role of genetic diversity in ecosystem function is vital to ensure the success of these attempts and the future health of Z. marina populations. The objective of this research project is to examine local and regional-scale patterns of genetic variability in eelgrass populations and how this genetic variation influences ecological processes.

Approach:

To evaluate the importance of genetic diversity in Z. marina for the function of the eelgrass ecosystem, I genotyped individual shoots using DNA microsatellites and transplanted them into the field to produce plots of equal initial shoot density, but varying from one to eight genotypes. At regular intervals, I quantified ecosystem functions such as primary productivity, secondary productivity, and nutrient cycling. Four months after transplantation, there was no consistent relationship between genetic diversity and epiphyte biomass or invertebrate abundance. However, a seasonal period of intense herbivory by geese revealed that more diverse plots tended to be more resistant to this grazing episode. Thus, the greatest benefit of genetic diversity may lie in enhancing the consistency and reliability of ecosystems in the face of environmental change.

To further assess the importance of genetic diversity to community structure and ecosystem function, I will evaluate patterns of genetic variation within and among natural eelgrass populations using DNA microsatellites previously identified for Z. marina. I also will investigate the effects of varying levels of genetic diversity on ecosystem variables such as eelgrass shoot density, flowering shoot production, and epiphyte and invertebrate biomass.

Ultimately, the results of these experiments can be utilized to plan and evaluate eelgrass restoration efforts to minimize changes in the overall genetic composition of eelgrass populations and maximize the success of transplant efforts.

Supplemental Keywords:

fellowship, ecological processes, habitat restoration, habitat degradation, water quality, Zostera marina, eelgrass restoration efforts.

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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