Production by the Amphipod Pontoporeia hoyi in South Bay, Lake Huron

Abstract

Pontoporeia hoyi was the dominant profundal benthic macroinvertebrate comprising 70–90% of animals collected and averaging close to 2100 m−2 in the main profundal basin of South Bay, Lake Huron. Almost all production occurred in the profundal zone (1.15 g∙m−2∙yr−1) compared with the sublittoral zone (0.03 g∙m−2∙yr−1), attributable to a preference by older P. hoyi for cooler temperature. Production/biomass (P/B) averaged 1.4∙yr−1 in the profundal zone at mean annual temperature of 4.7 °C and 3.1∙yr−1 at 7.5 °C in the sublittoral zone. Instantaneous growth rates were the same as in the Bay of Quinte and adjacent Lake Ontario where production was six times that in South Bay. A similar difference in phytoplankton production occurred between the areas. Differences in biomass accounted for variation in P. hoyi production in the two areas. The South Bay data provide further evidence that benthic macroinvertebrate biomass reflects production consistent with values of P/B determined by temperature.