Document: HEA-3-51-7

The effect of marsh edge on early life stage abundances of brown shrimp: Implications of an individual-based simulation model.

HAAS, H.L*, K.AROSE and R.FSHAW

Louisiana State University, Baton Rouge, LA USA ¹

Abstract:
We created a spatially explicit individual-based model to simulate brown shrimp (Penaeus aztecus) production in coastal wetlands. The model begins with the arrival of postlarval shrimp in the estuary and simulates growth, movement, and mortality on two tidal cycles per day until individuals emigrate to the ocean at about 60 mm length. Marshscapes are modeled with a grid of habitat-specific 1 m x 1 m cells created from a land/water classification of aerial photographs. When shrimp are in vegetated cells, their individual daily growth is faster and their mortality is lower. We used the model to test the hypothesis that shrimp production increases with increasing edge. We applied the model to two marshscapes with similar land/water ratios but different amounts of edge habitat (i.e., many small patches versus a few large patches). Simulation results indicate that the relationship between shrimp production and edge is complex due to the nonlinear effects of the spatial arrangement of habitat on shrimp survival and growth. Predicted survival varied up to two-fold between the marshscapes with different landscape patterns. Our results emphasize the importance of understanding the non-linear effects of habitat fragmentation in estuarine nursery areas.

Keywords: individual-based model, shrimp production, edge, habitat fragmentation

This abstract is being presented at: 4:30 PM in session:
Oral Session #47: Zooplankton Ecology.