|Session VII: Marine Ecology
||Abstract #: 97701
ANALYSIS OF SPONGE MORTALITY IN FLORIDA BAY
Barbara A. Maloney and Charles H. Bigger
Dept. of Biology, Florida International University, Miami, FL
Between January 1991 and 1994 there were a series of algal bloom incidents in Florida Bay that occurred at the same time as mass mortalities or disappearances of sponges, seagrass beds, juvenile fish and shellfish. Both the algal bloom and perhaps suspended fine sediments were blamed for the sponge mortalities. The major hypotheses advanced for the sponge death were physical clogging of the filter feeding mechanism by the putative bloom cynobacteria and its mucus or toxins produced by the cynobacteria. (Grantham, 1993). In October 1993, four species of sponges (Aplysina califormis
, Ircinia campano
, Spheciospongia vesparium
, Appotos sp.
) were collected from a normal area east of the Marine Lab in Long Key, Florida and transplanted into the mortality area where a single species, Cirayhydra alloclada
, was still growing. Accordingly, the sponges in this study were in three areas: 1) offshore, in the bloom area 2) inshore in a control area at the Marine Lab and 3) in a flow-thru sea water tank at the Marine Lab. Tissue was sampled daily over a five day period and fixed in Parducz's fixative or gluteraldehyde with osmium tetroxide as a postfixative and prepared for light, transmission electron and scanning electron microscopy. No physical clogging, by the dominant bloom species of cynobacteria, Synechoccus elongatus
or calcium carbonate particulates was found.
A special thanks to Florida Marine Research Institute, South Florida Regional Laboratory for assistance in collecting samples.