Detailed Reference Information

The intensity of isopod grazing was compared between temperate Baltic Sea (60°N, Finland) and subtropical Gulf of Mexico (30°N, U.S.A.) species assemblages. In laboratory consumption experiments, Idotea balthica (Finland) and Erichsonella attenuata (U.S.A.) were offered separately: epiphytes on artificial blades, and the three dominant species of submerged aquatic vegetation (SAV) in both study areas, i.e., Zostera marina, Ruppia maritima, Potamogeton pectinatus in Finland, and Thalassia testudinum, Ruppia maritima, Halodule wrightii in the U.S.A. Isopod consumption rates of SAV varied greatly in both regions, but mean consumption rates were higher in the U.S.A. than in Finland. In Finland, isopod consumption of epiphytes on artificial blades was clearly higher than feeding on live seagrasses, while the opposite was found to be true in parallel experiments conducted in the U.S.A. The calculated impact of isopods on the net above-ground primary production (mg dw · m-2 · d-1) of Z. marina and T. testudinum, yielded leaf losses between 2 and 15% (I. balthica) and of 7-30% (E. attenuata), respectively.