Coupling Behavior and Vertical Distribution of Pteropods in Coastal Waters Using Data from the Video Plankton Recorder.

摘要

LONG TERM GOALS. A combination of empirical, theoretical, and field studies are being used to develop a method for making accurate short- term (hours-days) predictions of the abundance and distribution of zooplankton, Limacina retroversa (Pteropoda, Thecosomata), in the ocean. This snail occurs in large numbers in coastal waters, forming dense patches (many kilometers in length) that are acoustically and optically opaque due to the animal's hard shell. A new conceptual approach is being developed to obtain behavioral information on individual plankton over a large range of spatial scales (1 cm-100 km). Still images from the Video Plankton Recorder (VPR) are being used to link behavior at the micro-scale to vertical and horizontal distributions of plankton over much larger scales. OBJECTIVES. The general hypothesis being tested is that the vertical distribution of the pteropod Limacina retroversa is predictable as a function of light, temperature, salinity, food concentration, stratification and mixing intensity. To accomplish this, the following objectives are being addressed: 1) To determine the effects of light intensity and phase, temperature, salinity, food concentration, stratification, and turbulence on the swimming behavior and vertical position of Limacina. 2) To develop a behavioral repertoire for Limacina relating body orientation, as viewed from a static image in the plankton, to a dynamic description of its instantaneous swimming behavior. 3) To couple objectives 1 and 2 through numerical modeling of pteropod behavior to allow projection of a pteropod population in space and time as a function of its behavioral responses to specific environmental characteristics. 4) To test the predictions of the numerical models with data collected on Georges Bank and the Southern New England Bight using both towed and moored Video Plankton Recorder instrumentation.