Ammonium enhancement of dark carbon fixation and nitrogen limitation in zooxanthellae symbiotic with the reef corals Madracis mirabilis and Montastrea annularis
Cook CB, Muller-Parker G, Orlandini CD. 1994. Ammonium enhancement of dark carbon fixation and nitrogen limitation in zooxanthellae symbiotic with the reef corals Madracis mirabilis and Montastrea annularis. Marine Biology. :157-162
Study on the nutrient status of dinoflagellates using ammonium and isolated symbionts. This was done in a lab. The nutrient status (limitation vs sufficiency) of dinoflagellates (zooxanthellae)sybiotic with reed corals in Bermuda was assessed in 1989 and 1990 by measuing the enhancement of dark carbon fixation with 20 uM ammonium by isolated symbionts. A colony of Madracis mirabilis was kept in the laboratory and fed daily or starved for one month. Symbionts from fed portions of the colony had ammonium-enhancement ratios similar to those of the original field population (1.2 to 1.3). Ammonium-enhancement ratios increased with starvation of the host as did values for VD:VL [(ammonium dark rate-seawater dark rate):light rate in seawater]. Both parameters indicated decreasing nitrogen sufficiency of the algae when the host was not fed, but starvation appeared to affect these algae less than symbionts of sea anemones. Field samples of zeexanthellae from M. mirabilis (Three Hill Shoals and Bailey's Bay Flats) yielded results similar to those for fed corals, but those taken from Bailey's Bay Flats in May 1990 yielded exceptionally high values for enhancement (greater than 3) and VD:VL indicating pronounced nitrogen limitation at the time of sampling. WE sampled zooxanthellae from populations of Montastrea annularis at 8 m (Three Hill Shoals) and 24 m (Soldier's Point) depths. Enhancement and VD:VL values for zooxanthellae from the 8 m corals were density-dependent: symbionts from corals with "normal" symbiont densities displayed the most nitrogen limitation (enhancement values = 1.4 to 2.0), while those from bleached corals with lower density exhibited enhancement and VD:VL values typical of nitrogen-sufficient algae. Symbionts isolated from the 25 m corals yielded the highest values, and appeared to exhibit the least nitrogen-sufficiency for this species.
- Type
- Journal Article
- Authors
- Cook, C.; Muller-Parker, G.; Orlandini, C.
- Units
- BISC
- Keywords
- Coral, Feeding, Madracis, Montastrea, Nitrogen (N), Nutrients, scleractinian coral, star coral, Stony corals, Zooxanthellae