Effects of nutrient enrichment and water motion on the coral Pocillopora damicornis

Exposure of the hermatypic coral Pocillopora damicornis to elevated levels of dissolved inorganic phosphorus did not affect the colony or the zooxanthellae. Exposure to elevated levels of dissolved inorganic nitrogen and inorganic N+P led to an increase in algal density, and as a result, to an increase in the chlorophyll concentration. These latter two experimental enrichments slowed skeletal growth rate of the corals, probably because of a decrease in the photosynthetic rate of the algae and perhaps a decrease in the translocation of photosynthetic products from the algae to the coral. The algae probably used the photosynthetic energy for their own increased growth. Experimental manipulation of water motion used in these experiments did not affect the coral or the symbiotic algae. -Authors