ABUNDANCE, BIOMASS AND PRODUCTION OF AQUATIC INVERTEBRATES IN RAINBOWBAY, A TEMPORARY WETLAND IN SOUTH-CAROLINA, USA

The abundance, biomass and production of aquatic invertebrates were de termined for 1992 and 1993 at Rainbow Bay, a small (maximum inundated area similar to 1.5 ha), shallow (maximum depth similar to 1 m) depres sion wetland in South Carolina, USA, which dries annually. Estimates w ere based on invertebrates collected from benthic substrates and the w ater column, including those associated with macrophytes. Mean inverte brate density during the Periods of inundation was 7.1x10(5) animals/m (2) in 1992 and 7.7x10(5) animals/m(2) in 1993. Small taxa, including nematodes, rotifers and microcrustaceans dominated numerically. Biomas s was 2.1 g dry mass/m(2) in 1992, and 0.9 g/m(2) in 1993. Oligochaete s, insects (mostly chironomids) and crustaceans dominated the biomass. The lower biomass in 1993 was the result of significant reductions in the biomass of oligochaetes and benthic chironomids. Laboratory-deriv ed daily growth rates of oligochaetes and chironomids collected from R ainbow Bay, along with daily production rates for crustaceans and roti fers derived from other studies were used to estimate secondary produc tion. Production in 1993 (14.7 g dry mass/m(2)) was less than in 1992 (36.7 g/m(2)), due primarily to lower biomass of oligochaetes and chir onomids in 1993. Differences between years in abundance, biomass and p roduction were associated with differences in hydrology of the wetland , including duration of inundation, and abundances of salamanders.