The effect of copper ions on behavior of larvae of the sea urchin Strongylocentrotus intermedius at different temperatures of sea water

We investigated the behavior of larvae of the sea urchin Strongylocentrotus intermedius at the blastula and early pluteus stages in the water column at a temperature of 20, 22, and 23.5°C and in the presence of copper in concentrations of 0.01 and 0.02 mg/l. In clean sea water, at all tested temperatures, sea urchin larvae preferred the subsurface layer to where they rose from the bottom of the vessel to form dense aggregations. In water supplemented with copper, the behavior of larvae at 20 and 22°C was not different from that in clean water. An increase in temperature to 23.5°C and the addition of copper altered the behavior of the larvae; they did not leave near-bottom water, did not rise to the surface, although they continued moving.