Size selective predation on invasive bivalve, Limnoperna fortunei (Mytilidae) by freshwater crab, Zilchiopsis collastinensis (Trichodactylidae).

TORRES, MARÍA VICTORIA; GIRI, FEDERICO; WILLINER, VERÓNICA

Mar del Plata

Conferencia; 2nd World Conference on Biological Invasions and Ecosystem Functioning; 2011

The size selective predation on invasive bivalve Limnoperna fortunei by freshwater decapods crustaceans could be an important point on the food selection, because shells sizes are correlated with the flesh contents and the resistance to be broken. In this study we investigate if the neotropical freshwater crab Zilchiopsis collastinensis feeds on invasive bivalve L. fortunei and if it selects any size of this mollusk. We considered three combinations (AC, AD and BD) of equal numbers of three different sizes of mussels: A (small) =7 to 10.99 mm, B (medium) =11 to 14. 99 mm and C=15 to 18. 99 mm and D= 19 to 22. 99 mm (larges) to shell length. These combinations were offered to each adult female intermoult crab individually, and the number of mussels remained was registered at first, second and at 24 hours. Female crabs ate more mussels of large size (C=2.77 ± 1.59; D=3.50 ± 1.46 and D=3.55 ± 1.50 mussels consumed) than small size (A=1.55 ± 1.33; A=1.83 ± 1.61 and B= 2.72 ± 1.77 mussels) in each combination at 24 hours and in the AD combination (0.27 ± 0.57 and 1.05 ± 1.69 mussels respectively) at the first hour. Large mussels were resulted preferred and consumed by crabs successfully and they showed certain efficiency in their handling, presenting a degree of plasticity advantageous for their predatory responses. L. fortunei can be a new resource in the diet of adult females of Z. collastinensis, showing a new interaction ?native predator-invasive prey? in the system.