Sublethal and acute toxicity of the ethylene glycol butyl ether ester formulation of triclopyr to juvenile coho salmon (Oncorhynchus kisutch).

The toxicity of Garlon4, the ethylene glycol butyl ether ester formulation of the herbicide tryclopyr, to juvenile coho salmon (Oncorhynchus kisutch) was investigated at several lethal and sublethal concentrations. Fish behavior, random activity and oxygen uptake were monitored. Coho salmon exhibited three distinct responses related to concentration and duration of exposure: (1) at concentrations greater than 0.56 mg/L fish were initially lethargic, then regressed to a highly distressed condition characterized by elevated oxygen uptake and finally death, (2) at 0.32-0.43 mg/L fish were lethargic throughout the exposure period with reduced oxygen uptake, and (3) at concentrations less than or equal to 0.10 mg/L fish were hypersensitive to stimuli, exhibiting elevated activity and oxygen uptake levels during photoperiod transitions. Whole body residue analysis showed that uptake of the ester and subsequent hydrolysis to the acid form in the fish was rapid, with significant accumulation of the acid in the tissues. This suggests that some threshold tissue concentrations were associated with the observed results. For juvenile coho salmon the 96-hr LC50 of Garlon4 was 0.84 mg/L.

In vitro effects of acephate on carbonic anhydrase activity in the blood and gills of rainbow trout, Salmo gairdneri.

Acephate, a water-soluble organophosphate pesticide used to control terrestrial insect pests, may enter aquatic ecosystems in the course of its use and adversely affect fish populations. The in vitro effects of this insecticide on gill and red blood cell (RBC) carbonic anyhdrase (CA) activity in rainbow trout were investigated over a range of 100 mg/1 (0.55 mM) to 50,000 mg/l (273 mM) to assess the manner in which acephate might affect respiratory capacity in exposed fish. Concentrations required to produce 50% inhibition of CA activity in the gill and RBC preparations were 38,000 mg/l (207 mM) and 8,900 mg/l (48 mM) respectively. The toxic action of acephate may be related to inhibition of CA activity in the blood and gills with resultant disturbances of respiratory capacity and salt balance.

Fate and toxicity of acephate (Orthene) added to a coastal B. C. stream.

Acephate was added to a small, coastal B. C. stream to yield a concentration of 1100-1200 ppb for a 5-h period. It was rapidly taken up by fish, sediments, insect nymphs and larvae. No fish or insect mortality was noted although the more toxic methamidophos was found in both groups of animals. Acephate and methamidophos residues in animals and sediments declined to trace or non-detectable levels in 24 h and to these levels in water by 96 h. The impact of acephate on the stream and its fauna was limited and localized.