Preliminary results on settlement of the barnacles Tetraclita stalactifera and Chthamalus bisinuatus on a Brazilian tropical rocky shore under upwelling conditions

摘要

The abundance of the larvae (nauplii and cyprids) and larval settlement of the barnacles Tetraclita stalactifera and Chthamalus bisinuatus were quantified on a rocky shore in the Arraial do Cabo region of Brazil from January to June 2000. This sampling period included times of spring/summer upwelling when water temperatures can fall from 24 deg C to 15 deg C. In the summer, densities of cyprids and settlement rates of both species were low, whereas densities of nauplii were high densities. By contrast, in autumn/winter, high densities of cyprids and high settlement rates were found, while densities of nauplii were lower than cyprids. These results may be related to higher water temperatures, which may accelerate larval metamorphosis, and/or due towinter storms that may increase transport to the shore. These results contrast with those from other upwelling regions where settlement is highest during spring/summer.