Field investigation on the toxicity of Alaska North Slope crude oil (ANSC) and dispersed ANSC crude to Gulf killifish, Eastern oyster and white shrimp.

A field investigation was conducted on a Louisiana Spartina alterniflora shoreline to evaluate the toxic effects of crude oil (Alaska North Slope crude oil, ANSC) and dispersed oil (ANSC + dispersant Corexit 9,500) on three aquatic species indigenous to the Gulf of Mexico: Fundulus grandis (Gulf killifish), Crassostrea virginica (Eastern oyster), and Litopenaeus setiferus (white shrimp). Results indicated that total hydrocarbons concentration value in oiled treatments decreased rapidly in 3h and were below 1 ppm at 24h after initial treatment. Corexit 9,500 facilitated more ANSC fractions to dissolve and disperse into the water column. L. setiferus showed short-term sensitivity to the ANSC and ANSC + 9,500 at 30 ppm. However, most test organisms (>83%) of each species survived well after 24h exposure to the treatments. Laboratory tests conducted concurrent with the field investigation indicated that concentrations of crude oil higher than 30 ppm were required for any significant toxic effect on the juvenile organisms tested.

Acute toxicity of permethrin to four size classes of red swamp crayfish (Procambarus clarkii) and observations of post-exposure effects.

The mean static acute 96-h LC50 of permethrin [(3-phenoxybenzyl (+) cis, trans, 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate)] to red swamp crayfish (Procambarus clarkii) 8-12 mm (0.017 g), 25-35 mm (0.64 g), 45-55 mm (2.45 g), and 65-75 mm total length (8.98 g) was 0.44, 0.85, 1.30, and 0.81 micrograms/L, respectively. Permethrin toxicity did not differ among immature or mature male and female P. clarkii. Crayfish surviving permethrin exposures exhibited no differences in post-exposure growth, survival, onset of sexual maturity, or the reproduction of viable young when compared to non-exposed controls. Teratogenesis was not observed in third-instar crayfish produced from permethrin-exposed parents.