Arnold, W. Florida DEP Marine Research Institute, arnold_b@epic7.dep.state.fl.us
Hitchcock, G. Univ. of Miami/RSMAS, ghitchcock@rsmas.miami.edu

 
PATCH DYNAMICS OF AN INTENTIONAL RELEASE OF LARVAL Mercenaria mercenaria IN THE INDIAN RIVER LAGOON, FL
 
Knowledge of physical dynamics is essential to evaluate the success of potential marine protected areas to maintain local fisheries. Physical processes, for example, influence larval retention within a given area through advective and diffusive processes. In July, 1998 we followed the dispersal of ca. 250 x 10^6 larvae of Mercenaria mercenaria released within a 5x5 km-square sampling grid in the Indian River, FL. Larval settlement was monitored from 25 settling chambers placed at 1 km intervals along the 5 x 5 km grid. Larval abundance in the water column was estimated by sampling 100 liters from mid-depth in the 2 meter deep water column and concentrating that sample in the cod-end of a 64 micron-mesh net. For both the larval trap and water column samples, clam abundance will be estimated by application of a Mercenaria-specific genetic probe. Movement of the larval `patch' was followed by tracking surface drifters patterned after the CODE drifter, with longitudinal and lateral diffusion coefficients determined by daily releases of Rhodamine WT dye. Over five days the patch moved north, and then west, in response to local winds. The larvae are predicted to have mainly settled along the northern boundary of the lagoon. Diffusion coefficients from dye release studies showed that the patch elongated parallel to the local winds, ostensibly distributing clam larvae in the lagoon mainly in response to wind forcing.
 
Day: Wednesday, Feb. 3
Time: 04:00 - 04:15pm
Location: Sweeney Center
 
Code: SS09WE0400S