PARENT SESSION
Oral Session #3: Plant Population Ecology. Presiding: N. Fetcher.
Monday, August 6, 2001. 8:00 AM to 11:30 AM. Hall of Ideas L&M.

It's not the size of your grass, it's where you plant it: Local adaptation in Chesapeake Bay eelgrass.

Rhode, Jennifer¹, Duffy, J.¹, ¹

ABSTRACT- Eelgrass (Zostera marina L.) is the Northern hemisphere's dominant marine angiosperm. Its populations serve as vital nursery habitats for many commercially-important fish and crustaceans, and eelgrass beds support complex food webs. We used reciprocal transplants of adult plants and seeds to determine if there was local adaptation within four morphologically, genetically, and geographically distinct Chesapeake Bay eelgrass populations. We monitored vegetative and sexual fitness of these transplants periodically for one (Transplant I) to two (Transplant II) years. We then used 2-way ANOVAs to determine whether site, source, or their interaction affected eelgrass fitness. For the Transplant I experiment, differences in vegetative and sexual fitness were due to both site and source effects. For the Transplant II experiment, differences in fitness could be attributed to site rather than source effects. Differences in vegetative fitness of seedlings were due to site effects and did not reflect maternal influences on seed biomass. Although we found unique temperature, light, and sediment signatures at each of the four sites, these were not correlated with differences in eelgrass performance. Managers should take site characteristics into careful consideration before attempting restoration projects.

KEY WORDS: local adaptation, seagrass, fitness, reciprocal transplant