| Ecological effects of pollution and organismal coping mechanisms are crucial to understand as marine contamination becomes increasingly common. Crude oil, one of the most common marine pollutants, is a potent cytotoxin and can inhibit primary cellular detoxification mechanisms such as multixenobiotic resistance (MXR). However, the relatively high abundance of macrofauna in areas of oil seepage has led ecologists to theorize that some organisms may be adapted to such pollution and that oil provides organic enrichment that benefits some resident populations. While enhanced MXR may protect many organisms from chronic oil exposure, its effect on tolerance to similar but unfamiliar contamination is unknown. Questions addressed in this study include: (1) whether a sub-population of sea urchins (Strongylocentrotus purpuratus) exposed to oil seepage endows offspring with enhanced MXR activity, and whether this response is adaptive or plastic, (2) the ecological cost(s) to adults and offspring of improved MXR activity, and (3) whether an infaunal community exposed to seepage reacts in a similar manner to foreign contamination. Results imply that female urchins from an oil seep improve MXR activity of their progeny relative to naive embryos. Furthermore, enhanced MXR activity in seep offspring is somewhat plastic, as embryos of adults removed from chronic oil exposure show depressed activity from only one of two transport protein types. The only fitness cost of this maternal effect detected in larvae was slightly depressed fertilization success, rather than egg size, larval growth rate, or survivorship. Adult sea urchins living with oil exposure are affected by slowed growth and low gonad mass, disproportionally so for females. Low to moderate levels of petroleum hydrocarbon input do not affect or mildly enhance infaunal abundance, depending on taxa, relative to clean sediment. However, moderate levels of a contaminant foreign to the oil seep community, the synthetic MXR inhibitor musk xylene, depress the density of many taxa in sediment trays at the oil seep. Thus, in this system familiar (oil) contamination did not induce toleration to a foreign (musk xylene) MXR inhibitor in arthropod, mollusk, or polychaete densities, but nematodes and oligochaetes tolerated both pollutants. |
