EVALUATION OF A CRAYFISH BURROWING CHAMBER DESIGN WITH SIMULATED GROUNDWATER FLOW

Crayfish are a highly diverse group of freshwater crustaceans with great ecological and economic importance. Many species construct terrestrial burrows within which they reproduce, overwinter, and/or avoid desiccation. Basic life-history and environmental tolerance information is still lacking for many species, particularly in regards to terrestrial portion(s) of their life cycle. In this paper we present and evaluate a design for a crayfish burrowing chamber that allows for experimental control of burrowing conditions, including substrate, groundwater height and flow, as well as direct observation of burrow construction and measurement of groundwater quality. Results of evaluation assays with Cambarus striatus, a widespread secondary burrower native to the southeastern United States show that chambers are amenable to studies examining burrowing behavior, survivorship, growth and water quality. Water table height was easily manipulated in chambers. Seepage rates were strongly affected by substrate type: burrows in coarse substrate filled rapidly but collapsed quickly whereas burrows in fine substrates filled very slowly and did not collapse. Cambarus striatus burrowed readily in fine substrate, produced complex burrows with chimneys, and exhibited high survivorship and positive growth over a 4 week period. Ammonia levels were higher in burrows than in the groundwater flowing through the chambers, but did not significantly affect growth or survivorship of C. striatus. Maximum burrow depth was significantly affected by substrate type, but not presence/absence of chelipeds. Suggested improvements include larger chamber size and the use of mesh barriers to keep crayfish from burrowing against the inner chamber walls.