Toxicity of some ricefield pesticides to the crayfish P. clarkii, under laboratory and field conditions in Lake Albufera (Spain).

Static toxicities in mature crayfish (Procambarus clarkii) were determined, for eight insecticides, two herbicides and one fungicide which were frequently used in rice cultivation at Lake Albufera in Valencia (Spain). Three concentrations of each product were used: a) The concentration that was recommended by the dealer (in mg/L of active ingredient): Carbofuran 0.40, Carbaryl 0.80, Malathion 0.80, Trichlorfon 0.40, Endosulfan 0.56, Lindane 0.56, Fenitrothion 0.40, Cyfloxylate 0.02, Molinate-Thiobencarb 1.50, Copper Sulfate 0.42, b) Half of the recommended concentration. c) Double of the recommended concentration. In all three of the concentrations tested, only Fenitrothion and Cyfloxylate caused a considerable mortality. The other ones do not actually produce any important effects on P. clarkii in our conditions. Nevertheless, insecticides are more toxic than herbicides or fungicides, as the latter show a rather low toxicity.

[Effect of temperature on the concentration of Ca2+, Mg2+, Na+ and K+ in the hemolymph and urine of Procambarus clarkii, Girard]. / Influencia de la temperatura sobre la concentración de Ca2+, Mg2+, Na+ y K+ en la hemolinfa y en la orina de Procambarus clarkii, Girard.

The concentration variability of Ca, Mg, Na, K ions in the haemolymph and urine has been analyzed in Procambarus clarkii during interecdysis instar, the animals having been kept under several temperature conditions (10, 15, 20, 25, 30 degrees C) during two different periods of time (48 h and 7 days). The environmental temperature did not affect the concentration of sodium and calcium in the haemolymph. Nevertheless the above parameter had an effect on the concentration of potassium and magnesium in the haemolymph as well as on the concentration of the four cations considered in the urine of Procambarus clarkii. No significant differences have been found in relation to the time of exposure.