Effects of sediment copper on a tube-dwelling estuarine amphipod, Paracorophium excavatum

Abstract

Amphipods, Paracorophium excavatum, were exposed for 10 days to copper-spiked sediments in the concentration range 3–84 µg g ^–1 dry wt of sediment. Percent emergence was low, ranging from 0.18% to 2.1%, but increased with exposure time and with copper concentration. Amphipod mortality increased with exposure time and sediment copper concentration, following a linear relationship; the Cu 10-day LC ₅₀ value was 55 µg g ^–1 . Mortality was <5% in the control (natural) sediment containing 3µg g^–1 copper. >85% of surviving amphipods reburied themselves within 1 h, and therefore this behaviour was not a good discriminator for potentially toxic sediments. The concentration of copper within the whole-body tissues of P. excavatum (µg Cu g ^–1 ) was mostly independent of dry body weight within the range 0.12–0.37 mg. Average copper concentrations within the tissues ranged from 169 to 490 µg Cu g ^–1 , with higher variability in amphipods exposed to sediment copper concentrations of 16 and 32 µg g ^–1 . Amphipod tissue copper concentration increased with sediment copper concentration. It was concluded that P. excavatum is a suitable indicator species for use in ecotoxicological tests for potentially toxic marine and estuarine sediments.