Effects of copper exposure on the metabolism of the mysid Praunus flexuosus

The metabolism of a coastal mysid population (Praunus flexuosus) from the W est Solent (South England) has been studied in different seasons (winter, s pring and summer). Metabolic responses to copper (0, 5, 25, 75 and 200 mug l(-1) copper added) were measured in winter and summer at 24 h, 96 h and 10 days of exposure. The metabolic rates of P. flexuosus in controls were dif ferent between seasons. Respiration and ammonia excretion were 2.5 to 6 tim es lower in winter than in summer. O:N ratios also varied significantly wit h season from 3.5-5 in summer to 8 in winter. Temperature dependency of res piration (Q(10) = 1.76) and excretion (Q(10) = 1.95) was moderate. Copper e ffects on metabolism resulted in a decrease of the O:N ratio, from values o r 10 to values between 4 and 2. The metabolic responses to copper were stro nger in summer than in winter. causing larger changes and being effective a t lower concentrations. Alterations of the O:N ratio found in this study we re a very sensitive indicator of sublethal and lethal toxicity. (C) 2001 El sevier Science B.V. All rights reserved.