Summary: FEEDING PREFERENCES AND FOOD SELECTION
OF THE RED SWAMP CRAYFISH, PROCAMBARUS CLARKII,
IN HABITATS DIFFERING IN FOOD ITEM DIVERSITY
PALOMA ALCORLO1), WALTER GEIGER and MARINA OTERO
Department of Ecology, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain
We compared the dietary composition, feeding preferences, and food selection of the introduced
crayfish, Procambarus clarkii in a natural and a transformed freshwater marsh (rice field) in the lower
Guadalquivir basin (southern Spain). Both habitats differed in hydroperiod and food item diversity.
Food item diversity in crayfish stomachs is correlated with prey availability, which is significantly
higher in the natural marsh. Herrera's index was low in both areas if compared with the theoretical
maximum. P. clarkii behaves like a generalist in this area and individual crayfish have very similar
The most frequent items in the stomach were fresh macrophytes, detritus, and sediment grains.
However, especially in the untransformed marsh, insect larvae formed an important part of the
crayfish's diet, up to 67% by occurrence, with a marked seasonal pattern: crayfish in this area
consumed significantly more animal prey in spring than in winter.
P. clarkii positively selects for insect larvae (mayflies, chironomids), snails, and microcrustaceans
except ostracodes. Negative selection against oligochaetes is explained by their burrowing behaviour