VCR-LTER Student Conference, September 1996 Title The ecological association between Spartina alterniflora, the salt marsh cord grass, and Littoraria irrorata, the marsh periwinkle.

Authors Brian Silliman and Jay Zieman Department Envisci Institution UVA

The ecological association between Spartina alterniflora., the salt marsh cord grass, and Littoraria irrorata, the marsh periwinkle.

Much evidence in the literature has pointed to the potential importance of grazing on the salt marsh cord grass, Spartina alterniflora, by the Gulf Periwinkle, Littoraria irrorata. The grazing effects of Littoraria on Spartina productivity, biomass, height, shoot C:N ratios, whole plant C:N ratios, and changes in porewater Eh were measured from 5/96 - 10/96. The experimental manipulation consisted of housing and maintaining snails in enclosure pens in both young and old marshes on Hog Island, Virginia. Three treatments were maintained: zero snails, natural occurring densities, and 3 times natural occurring densities. Initial results suggest that increased snail populations may have a profound effect on Spartina biomass, productivity, and height.

Predation rates of Littoraria along a creekbank void of Spartina were also measured. All tethered snails were taken after three weeks. Further experiments may show that the presence of Spartina along creekbanks decreases the predation rates of Littoraria by Calinectus sapidus, the blue crab. With these results, I hope to define the ecological relationship between the marsh periwinkle and the salt marsh cord grass.

Return to table of contents.