|Session VI: Bird & Animal Studies
||Abstract #: 97605
BENTHIC MACROPHYTE SEASONALITY IN THE EVERGLADES-FLORIDA BAY ECOTONE: INFLUENCE OF FRESHWATER INFLOW
Morrison, D., Bean, D., Wise, M., and Sorrentino, D.
National Audubon Society, 115 Indian Mound Trail; Tavernier, FL 33070
Water management practices have altered the natural freshwater flow patterns into the mangrove ecotone zone along the north shore of Florida Bay. This study characterizes seasonal patterns of submerged macrophytes in the estuarine waterbodies in this zone. We evaluate the influence of freshwater inflow on macrophyte dynamics. This project provides information for developing and evaluating management strategies to restore more natural freshwater inflow patterns.
Two sampling regimes were used to assess benthic macrophyte seasonal abundance, distribution, and community structure: 1) at the end of wet and dry seasons on a waterbody wide scale measuring percent cover, and 2) on a smaller spatial scale, but with greater frequency (every two months, measuring biomass. Eight waterbodies, oriented along freshwater flow paths (hence, salinity gradient) from inland to Florida Bay, were surveyed. Project duration was October 1995 to December 1996 (two wet and one dry season surveys).
Submerged macrophyte abundance and distribution varied seasonally. Benthic macrophyte seasonality was related to seasonal patterns in salinity and light penetration or water clarity. However, these biological and physical patterns differed spatially and temporally. Macrophyte seasonal patterns differed among waterbodies, and even within some waterbodies. Seasonal patterns differed in the same waterbody from year (1995 wet season) to year (1996 wet season). These differences in macrophyte seasonal patterns are likely due to the relative importance of different physicochemical factors, primarily salinity and light, affecting plant growth over spatial (among waterbodies) and temporal (interannual) scales. Salinity and benthic light availability are affected by freshwater inflow patterns. Chara
was the dominant species in waterbodies with median salinity <15 ppt. Halodule
was abundant in waterbodies with median salinity >18 ppt.