Impacts of Limnoperna fortunei on zooplankton

ROJAS MOLINA FLORENCIA; JOSÉ DE PAGGI SUSANA; PAGGI JUAN CÉSAR

Limnoperna fortunei: the ecology, distribution and control of a swiftly spreading invasive fouling mussel

Springer

Año: 2015; p. 177 - 190

In addition to phytoplankton, adult Limnoperna fortunei feed actively on animal prey, consuming over 150 different organisms, including Protista, Rotifera, Nematoda, Cladocera, Copepoda, Ostracoda, and L. fortunei larvae. Animals are present in the stomachs of 96 % of the individuals analyzed representing, on average, 67 % of ingested biomass. Rotifers are the most frequent animal prey, followed by cladocerans and copepod nauplii. Comparison between the abundances of prey in plankton samples and the diet of L. fortunei indicates that all animals are positively selected, with the highest selectivity for the rotifers and small cladocerans. Selectivity is positively associated with prey size and negatively with avoidance capabilities. This selective grazing pressure is probably responsible for the fact that rotifer densities have dropped in several water bodies associated with the Middle Paraná River after L. fortunei colonized the area, while cladocerans and copepods remain at pre-invasion levels. In addition, grazing pressure probably accounts for significant post-invasion decreases in zooplankton density differences during low- and high-water periods. Densities of L. fortunei veligers normally exceed those of rotifer + crustacean zooplankton for 8?9 months of the year, underscoring their potential significance as competitors of other zooplankton for food, and as food for various animals.