The amphipod Corophium multisetosum (Corophiidae) in Ria de Aveiro (NW Portugal). II. Abundance, biomass and production

Abstract

The abundance and biomass of Corophium multisetosum Stock, 1952 were determined from benthic corer samples collected monthly over 1 yr in the upper reaches of Canal de Mira (Ria de Aveiro, Portugal). Both density and biomass over the sampling period were negatively correlated with water temperature and positively correlated with chlorophyll n concentration in the sediment. C, multisetosum density was significantly negatively correlated with plant biomass and positively correlated with salinity. The nature of the sediment, favourable environmental conditions, high availability of food and low interspecific competition allowed the population to reach a maximal density of 200 x 10(3) individuals m(-2) and a maximal biomass lash-free dry wt, AFDW) of 62 g(AFDW) m(-2) The population was highly productive, especially during the autumn/winter period. Production, estimated by two different methods (Hynes method: 251 gAFDw m(-2) yr(-1); Morin-Bourassa method: 308 g(DW) m(-2) yr(-1)), was much higher than the values reported for other Corophium species. The annual P:(B) over bar ratio (10) was high, but similar to values reported for Swedish populations of C. volutator and lower than the values estimated from Mediterranean populations of C. insidiosum.