Effects of copper exposure on the metabolism of the mysid Praunus flexuosus
The metabolism of a coastal mysid population ŽPraunus flexuosus. from the West Solent South England. has been studied in different seasons winter, spring and summer.. Metabolic responses to copper 0, 5, 25, 75 and 200 mg ly1 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 different between seasons. Respiration and ammonia excretion were 2.5 to 6 times lower in winter than in summer. O:N ratios also varied significantly with season from 3.5–5 in summer to
8 in winter. Temperature dependency of respiration Q10s1.76. and excretion Q10s1.95. was moderate. Copper effects on metabolism resulted in a decrease of the O:N ratio, from values of 10 to values between 4 and 2. The metabolic responses to copper were stronger in summer than in winter, causing larger changes and being effective at lower concentrations. Alterations of the O:N
ratio found in this study were a very sensitive indicator of sublethal and lethal toxicity.