MEPS 151:91-102 (1997)  -  doi:10.3354/meps151091

The lethal and sublethal toxicity of phenanthrene (a polycyclic aromatic hydrocarbon, PAH) to 2 species of meiobenthic estuarine harpacticoid copepods (Schizopera knabeni and Nitocra lacustris) was investigated. Individuals of different life stages (nauplius, copepodite, adult male and female) were exposed to sediment-associated phenanthrene in separate 10 d bioassays. Overall, N. lacustris (10 d LC₅₀ valuesranging from 43 to 105 µg g^-1 dry wt) was more sensitive than S. knabeni (10 d LC₅₀ valuesranging from 84 to 349 µg g^-1 dry wt). Significant differences in life-stage-specific sensitivity were observed for S. knabeni, with the nauplii being most sensitive, followed by copepodites, and adults; adult males and females were equally sensitive. For N. lacustris, females were significantly more sensitive than all other stages; no significant differences were evident among the other stages. Phenanthrene effects on offspring production were investigated in the adult 10 d bioassay. Significant decreases in offspring production occurred at sublethal concentrations for S. knabeni (as low as 22 µg g^-1 dry wt), but at concentrations in the same range as the 10 d LC₅₀ values for N. lacustris. In addition, phenanthrene significantly prolonged embryonic and larval development and decreased egg hatching success for both species. Our results suggest that PAHs have a negative effect on the reproduction of meiobenthic copepods at sublethal concentrations mostly due to a decrease in brood production rate and impairment of hatching. Overall, deleterious effects were manifested in the same range of concentrations for both species, but definite species-specific differences in the pattern of responses were evident.

Sediment toxicity · Copepod · Life history · Meiobenthos · Phenanthrene