Nitrogen and photosynthetic function of hermatypic corals. Oxygen exchange of Stylophora pistillata coral under artificial feeding.
The change of Stylophora pistillata coral photosynthetic function (oxygen exchange and biomass of symbionts) under starvation and food enrichment was studied to understand the role of heterotrophy in nitrogen supplements of zooxanthellae. The starvation caused the decrease of frequency of zooxanthellae cells division in 7-10 times. The number of degraded algae cells increased in same proportion and, as a result, the density of zooxanthellae in corals decreased about two times during one-two weeks. Under starvation corals kept their photosynthetic capacity at the level of corals in situ by means of enhancing the zooxanthellae gross photosynthesis. The respiration rate of coral had tendency to increase and the dry mass of polyp tissue to decrease. Under artificial feeding which was following starvation the zooxanthellae density increased in 1.5-2 times, and particular food caused more intensive accumulation of zooxanthellae comparing to dissolved inorganic ammonium. The feeding regime did not affect dry mass of polyp tissue and chlorophyll content as well as respiration and gross productivity of the corals. The conclusion about high effectiveness of particular feeding for supplying symbiotic algae with nitrogen was made and trophic status of zooxanthellae in hospite was determined as unlimited by nitrogen.
Leletkin
V A
VA
Tropical Biosphere Research Center, University of the Ryukyus, Okinawa 905-02, Japan. vladletet@stl.ru
D000818:Animals; D037421:Anthozoa / Q000254:growth & development* / Q000378:metabolism; D018533:Biomass; D056890:Eukaryota / Q000254:growth & development* / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D009792:Oceans and Seas; D010100:Oxygen / Q000378:metabolism*; D010788:Photosynthesis / Q000502:physiology*; D012403:Rotifera / Q000502:physiology; D013559:Symbiosis / Q000502:physiology*; D013696:Temperature
D009584:Nitrogen; D010100:Oxygen