Aquatic Sciences Meeting, Albuquerque 2001

SS45 Temporary Aquatic Ecosystems: Here Today, Gone Tomorrow (Spatial and Temporal Connections)

Date: Wednesday, February 14, 2001, Time: 4:00:00 PM

Location: Cochiti/Taos

Brendonck, L, , K. University Leuven, Leuven, Belgium, Luc.Brendonck@bio.kuleuven.ac.be

Riddoch, B, J, University of Botswana, Gaborone, Botswana, riddochb@mopipi.ub.bw

PERSISTENCE IN EPHEMERAL ROCK POOLS: RACING AGAINST TIME AND SPREADING OF RISKS

Early drying of desert rock pools is a major threat to the fairy shrimp Branchipodopsis wolfi. The egg bank densities varied between 1,000 and 220,000 eggs per m2, illustrating the effectiveness of the reproductive and hatching characteristics. Females were fully mature within eight days in most pools. Maturation rate was faster and broods had smaller eggs in the more short-lived (unpredictable) pools. Delayed hatching hedged against at least 16 subsequent drought catastrophes. Hatching percentages under the most likely field temperatures after filling of pools (20-30°C), ranged between about 3 and 20%, corresponding with yield expectations predicted from long-term climatic records. Conditional responsiveness to ecologically informative hatching cues, restricted hatching of resting eggs to initial or additional rains. Eggs were dispersed by wind at least at the local scale. The regional population genetic structure points indirectly at the importance of short-range dispersal. Direct observations during abundant rains revealed overflowing floating cysts between neighboring pools. By generating egg banks with delayed hatching and with egg types with different potential dispersibility, B. wolfi escapes stress both in time and in space.

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Aquatic Sciences Meeting, Albuquerque 2001

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