SUBLETHAL EFFECTS OF CUPRIC ION ACTIVITY ON THE GRAZING BEHAVIOR OF 3CALANOID COPEPODS

This research (1) characterized the effects of sublethal cupric ion ac tivities on the grazing behavior of two estuarine copepods (Acartia to nsa, Acartia hudsonica) and one nearshore, neritic copepod (Temora lon gicornis) and (2) compared the sensitivity of short-term sublethal beh avioral assays with that of longer-term acute toxicity tests. A nitril otriacetate-trace-metal-ion buffer system at 27 parts per thousand. S was used to quantify and control the free cupric ion activity. Acute t oxicity tests were used to determine the mortality of A. tonsa and T. longicornis over 72 h within the approximate cupric ion activity range of 10(-13) to 10(-9.5) M. 24 h survival was not affected within the a pproximate cupric ion activity range of 10-13 to 10(-9.7) M, the range used for subsequent grazing activity experiments after 24 h exposure to Cu. Grazing activity was significantly diminished at cupric ion act ivities of approximate to 10(-10) M for A. tonsa and T. longicornis, a nd at approximate to 10(-11) M for A. hudsonica. A hermetic pattern of response in feeding activity was observed with A. tonsa and T. longic ornis. Grazing activity was found to be a sensitive measure of subleth al Cu stress compared with the acute toxicity tests. Grazing activity was affected at environmentally relevant cupric ion activities. (C) 19 97 Elsevier Science Ltd. All rights reserved.