Population characteristics of the estuarine isopod Gnorimosphaeroma insulare in three contrasting habitats: sedge marsh, algal bed, and wood debris

Population characteristics of Gnorimosphaeroma insulare (Isopoda: Sphaeromatidae) were investigated in three habitats within the Squamish estuary, British Columbia: a log debris area, an embankment along the perimeter of a Carex lyngbyei marsh, and a Fucus distichus community. Gnorimosphaeroma insulare annual production was highest in the Fucus habitat (39.54–48.05 g dry wt∙m−2∙year−1) followed by "bank" (22.97–27.74 g∙m−2∙year−1) and then wood debris habitats (4.72–6.43 g∙m−2∙year−1). Cohort figures indicated that male productivity was greater than female productivity in all locations. Production:biomass ratios were similar in all three habitats and ranged between 2.47 and 3.17. Mortality rates were greatest in Fucus; those in wood debris and bank habitats were similar. Growth rates were highest in the bank habitat; those in wood debris and Fucus were similar. Growth and mortality rates of males were greater than those of females. Gnorimosphaeroma insulare is an annual semelparous species. Males died soo...