The abundance and size composition of stream isopods Lirceusfontinalis were investigated from April 2001 to August 2002 in 3 streams in southem Ontario, Canada. Effects of current speed was released from the analysis ...The abundance and size composition of stream isopods Lirceusfontinalis were investigated from April 2001 to August 2002 in 3 streams in southem Ontario, Canada. Effects of current speed was released from the analysis by choosing slow flowing water. The effects of substrate, season and water depth on the abundance, distribution and size composition of the isopods were analyzed. It was found that substrate and season influence isopods the most. The rocky substrate with attached filamentous macro-algae contains an isopod abundance 7.05 times that of bare rock substrate and 14.6 times that of free-sand and mud substrate. There was a large variation with respect to seasonali .ty in both abundance and size composition of the isopods, with the highest abundance occumng in summer and the lowest in winter and spring; individual isopods also tend to be larger in the winter and spring. In all substrates, shallow areas tend to support higher densities of isopods than deeper areas.展开更多
文摘The abundance and size composition of stream isopods Lirceusfontinalis were investigated from April 2001 to August 2002 in 3 streams in southem Ontario, Canada. Effects of current speed was released from the analysis by choosing slow flowing water. The effects of substrate, season and water depth on the abundance, distribution and size composition of the isopods were analyzed. It was found that substrate and season influence isopods the most. The rocky substrate with attached filamentous macro-algae contains an isopod abundance 7.05 times that of bare rock substrate and 14.6 times that of free-sand and mud substrate. There was a large variation with respect to seasonali .ty in both abundance and size composition of the isopods, with the highest abundance occumng in summer and the lowest in winter and spring; individual isopods also tend to be larger in the winter and spring. In all substrates, shallow areas tend to support higher densities of isopods than deeper areas.
