Crayfish species composition and abundance are indicators of hydroperiod and are predictably influenced by hydromanagement. Two species of crayfish inhabit south Florida marshes. The Everglades crayfish, Procambarus alleni, is found in locations that dry seasonally (typically with a hydroperiod of less than 10 months), and it burrows when water recedes from the surface. The slough crayfish, P. fallax, is found in perennially flooded habitats and, although capable of burrowing, has not been observed in burrows in the field. Sympatric populations were found in locations that were flooded from 9 to 11 months (intermediate hydroperiod), or at sites that remained flooded in the dry season. This distribution pattern is useful in back-casting and in predicting the relative occurrence of species.

Life-history characteristics of each species are tied to different hydrologic requirements. For example, reproduction in the Everglades crayfish occurs synchronously and coincides with loss of water from the surface, whereas the slough crayfish breeds almost continuously. The species-specific responses to hydropattern are predictable and can be modeled. Spatially explicit models that incorporate the dynamics of crayfish response to variation in hydrology are being constructed. The results of this project will address how the loss of spatial extent, fragmentation of habitat, and compartmentalization of the watershed, have combined to affect crayfish distributions and abundance. These topics are important when considering that white ibis (Eudocimus albus) consume crayfish almost exclusively during nesting, and that foraging flight distance is markedly reduced when crayfish are locally available. Using Across Trophic Level Systems Simulation (ATLSS) wading bird models, the role of crayfish as an intermediate through which hydrology may affect nesting success can be addressed.

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(This abstract was taken from the Greater Everglades Ecosystem Restoration (GEER) Open File Report (PDF, 8.7 MB))

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