Copper tolerance of the life history stages of the splashpool copepod Tigriopus californicus (Copepoda, Harpacticoida)

Abstract

High concentrations of copper were used to test the hypothesis that a species tolerant to large changes in natural conditions will exhibit tolerance to elevated levels of chemical contamination. The harpacticoid copepod Tignopus californicus was used as a test species because it occurs in supralittoral splashpools and is tolerant to wide-ranging conditions of temperature and salinity. Life history stages were exposed to concentrations of total dssolved copper between I O - ~an d I O - ~M in a defined medium without organic metal-complexing agents and without food. The 96-h LC,, and LCg5 values were higher for the egg embryo) than for most of the naupliar stages. They were highest for the adult. With the exception of the adult, the 96-h values for total copper were within the range of 24-h and 48-h LCS0 values reported for other copepods in copper-enriched natural seawater When considered in terms of cupric ion activity, however, T. californicus tolerated levels of activity 2 to 3 orders of magnitude higher than those reported for other copepods. These results support the hypothesis that innate tolerance to extremes of natural environmental conditions correlate with tolerance to chemical contamination. They also suggest that natural tolerance must be considered in the selection of bioassay organisms.