Aquatic Sciences Meeting, Albuquerque 2001

SS35 Biological and Ecological Responses to Low Oxygen in Constant and Fluctuating Environments (Spatial and Temporal Connections)

Date: Thursday, February 15, 2001, Time: 10:45:00 AM

Location: La Cienega

Decker, M, B, Horn Point Laboratory, University of Maryland Center for Environmental Science, Cambridge, USA, mdecker@hpl.umces.edu

Breitburg, D, L, Estuarine Research Center, Academy of Natural Sciences, St. Leonard, USA, breit@acnatsci.org

Marcus, N, H, Department of Oceanography, Florida State University, Tallahassee, USA, marcus@ocean.fsu.edu

BEHAVIORAL RESPONSES OF ZOOPLANKTON TO HYPOXIA IN A STRATIFIED WATER COLUMN: COMPARISON OF TWO POPULATIONS OF ACARTIA TONSA.

The occurrence of low dissolved oxygen, caused by vertical stratification and excess nutrient inputs, is an important widely occurring physical feature in aquatic systems. Shifts in vertical distributions of zooplankton have been documented where bottom waters are severely hypoxic. However, little is known of the behavioral adaptations that allow zooplankton to survive in such a system. The behavioral responses of calanoid copepods (Acartia tonsa) to low dissolved oxygen were examined. Two populations of Acartia tonsa were tested: one from a seasonally stratified tributary of Chesapeake Bay and the other from a well-mixed region in the northern Gulf of Mexico. We examine the possibility that Acartia tonsa are locally adapted to hypoxia by distinguishing between phenotypic and genetic differences between populations. Our results suggest that in zooplankton populations that have been exposed to oxygen gradients, behavioral responses to vertical gradients in oxygen may result in shifts in vertical distributions. In contrast, populations without pre-exposure to strong oxygen gradients may not have the ability to avoid lethal concentrations of dissolved oxygen, and thus are more vulnerable during hypoxia events.

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Aquatic Sciences Meeting, Albuquerque 2001

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