Effects of light and dark treatments on feeding by the reef coral Pocillopora damicornis (Linnaeus)

The feeding capability of Pocillopora damicornis (Linnaeus) was measured by exposing segments of the same colony to different densities of Artemia salina (L.) nauplii and determining the number of ingested prey. Feeding is directly related to prey density. No plateau in feeding capability was observed over the range of prey densities used.The effects of reduced photosynthesis on feeding capability and tissue dry weight were also examined in colonies maintained in unfiltered running sea water. Tissue samples from clonal segments of Pocilloporadamicornis colonies maintained in a covered (dark) sea table for 2 days or 15 to 17 days weighed significantly less than equivalent samples from segments maintained in a normal (light) sea table. Segments maintained in a darkened sea table for over 2 wk were unable to ingest as many Artemia nauplii as their light table equivalents. These data indicate that the amount of Zooplankton available to the colonies in the sea table was insufficient to meet their metabolic requirements and that feeding in Pocillopora damicornis was dependent upon energy derived from photosynthesis by the zooxanthellae.