PARENT SESSION
Poster Session #13: Salt Marshes.
Monday, August 5. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC
133
Patterns of marsh surface use by larval and juvenile Fundulus heteroclitus in a northeastern Florida estuary.
Smith, Kelly*,1, 1 University of North Florida, Jacksonville, FL
ABSTRACT- The intertidal salt marsh surface is an important habitat for larval and juvenile resident salt marsh fishes such as Fundulus heteroclitus. A number of factors are known to influence larval fish abundance on the salt marsh surface. This study addresses how larval and juvenile F. heteroclitus abundance varied with emergent vegetation type and geographic location within an estuarine system in northeast Florida, over a sampling season. Three geographic locations (sites) were selected within the St. Johns River estuarine system, ranging from 1 to 5 km in distance from the confluence between the river and a dredged channel leading to the tidal creek system. Each site had adjacent stands of Juncus roemerianus and Spartina alterniflora. A grid of 16 pit traps (10 cm x 5cm glass evaporating dishes) was set into the sediment within each vegetation type at each site (total N = 96). Sampling was conducted about every 2 weeks, from March 8, to June 21, 2001, and pit traps collected larvae over one spring tide inundation event per sampling date. Contents were collected and transported to the laboratory for identification and measurement. A total of 576 pit trap samples were collected that contained 151 larval and juvenile Fundulus heteroclitus. Of these, 40% (59) were newly hatched larvae. Results of a two-way repeated measures ANOVA examining the effect of site and vegetation type on larval abundance over 6 sampling dates found a significant three-way interaction between site x vegetation type x sampling date (F2,5=2.5, p = 0.008). Overall, catches tended to be variable over dates with the highest catches in the site most distant from the river (5 km location) within Spartina alterniflora. The relative importance of geographic location within an estuarine system as well as emergent vegetation type may have important implications for salt marsh management.
KEY WORDS: Salt marsh, Fundulus, Florida