Invertebrate Faunas and Crawfish Food Habits in Louisiana Crawfish Ponds

Aquatic invertebrate fauna and crawfish (Procambarus spp.) stomachs were sampled monthly (October 1981-April 1982) in a crawfish pond dominated by rice (Oryza sativa). Invertebrate fauna only was sampled during the same period in a nearby pond dominated by alligator weed (Alternanthera philoxeroides), a perennial, semi-aquatic forb. Macroinvertebrates were affected by the gradual disappearance of rice stubble in the rice pond. Clinging insects such as dragonfly naiads and mayfly nymphs were abundant when vegetation was present but were replaced by small, bottom dwelling crustaceans (amphipods and mysid shrimps) and free swimming insects (backswimmers and water boatmen) as vegetation disappeared. Tubificids and microcrustaceans were the dominant organisms recovered from benthic cores and zooplankton samples, respectively. Stomach analyses of crawfish indicated that the balance of diet volume was composed of plant detritus and/or fresh plant material. Less than 10% was composed of identifiable animal material. Cladocerans and ostracods were commonly ingested, and amphipods, mayfly nymphs. and mysid shrimp were consumed when abundant. Tubificid worms, though abundant in the pond, did not appear to be important food items.

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