Effects of Shading on Environmental Parameters, Population Dynamics and Copper Tolerance in the Marine Copepod Tigriopus californicus

The copepod, Tigriopus californicus, is able to withstand copper concentrations at least 5000 times greater than those found in coastal waters. However, great variation of copper tolerance exists between populations, possibly influenced indirectly by environmental factors that are variable across sites, such as the amount of shade. This experiment determined that levels of shading significantly influenced environmental parameters such as temperature and salinity. Initial principal components analysis with corresponding analysis of variance demonstrated that all environmental parameters (water level, temperature, salinity, pH, UV radiation, Photosynthetically Active Radiation) across all three shading treatments were significantly different, but there were no significant differences in male mortality across the treatments. After exposing the organisms from each shade treatment to varying copper concentrations, results showed that female copepods from the completely shaded treatment displayed reduced copper tolerance.

Keywords: Evolution, local adaptation, Tigriopus californicus, copper toxicity, tidepools