N.C. STATE UNIVERSITY

College of Agriculture and Life Sciences
N.C. Agricultural Research Service
N.C. Cooperative Extension Service

Impacts of Coastal Development on Seagrass Species that Serve as Vital Fisheries Habitat

Prepared by: JoAnn M. Burkholder

Published by: North Carolina Cooperative Extension Service

Publication Number:

Last Electronic Revision: January 1997 (MSD)

Major Long-Term Objectives:

1. Examine physiological mechanisms that control the "nitrate toxicity" effect on survival of North Carolina's most important seagrass habitat species, Zostera manna.

2. Develop metabolic or physiological parameters (e.g., activity of certain enzymes, or nutrient content of plant tissue) that can be used to indicate stress from nutrient over-enrichment and high suspended sediment loading. Improve general methods for ensuring seagrass survival during transplanting to re- habilitate areas with habitat loss, including use of seagrass species that are tested to be more tolerant of nutrient over-enrichment.

Major Short-Term Objectives:

1. Determine whether the inhibitory effects of water-column nitrate enrichment act through elevated internal ammonia concentrations, or through intemal P limitation.

2. Examine impacts of nitrate enrichment on carbon storage in the rhizomes.

Accomplishments:

1. Discovered that water-column nitrate enrichment causes death to Zostera manria as a direct physiological impact, unrelated to algal turbidity.

2. Demonstrated that water-column nitrate enrichment acts synergistically with increasing temperatures to promote Zostera decline.

3. Demonstrated that water-column nitrate enrichment acts synergistically with decreasing light availability to promote Zostera decline.

Significance:

The insights from this research will greatly strengthen seasonal strategies for management, protection, and establishment of submersed vegetation in eutrophic coastal waters. These studies will also provide data for improving guidelines to control coastal development near seagrass habitat.

Future Plans:

1. To test whether the adverse effects of water-column nitrate enrichment on Zostera (simulating septic effluent leachate) can be mitigated by co-enrichment with phosphorus (simulating sewage, which has a higher P "signature").

2. To conduct field tests to examine the utility of tissue C, N, and P content as an index of cultural eutrophication.

Published by: North Carolina Cooperative Extension Service

Publication Number:

Last Electronic Revision: January 1997 (MSD)