Metabolism in corals from Antarctica, the deep-sea, and the shallow subtropics: contrasts in temperature, depth, and light

• Main Author: Henry, Lara
• Format: Doctoral or Postdoctoral Thesis
• Language: unknown
• Published: Digital Commons @ University of South Florida 2013
• Subjects: coral; depth; light; metabolism; respiration; temperature; Other Oceanography and Atmospheric Sciences and Meteorology; Antarc*; Antarctica
• Online Access: https://digitalcommons.usf.edu/etd/4903; https://digitalcommons.usf.edu/context/etd/article/6099/viewcontent/Henry_usf_0206D_12112.pdf

Coral habitats span the range from tropical to polar, extremely shallow to thousands of meters deep. The differences in light and temperature experienced in these varied habitats likely affect the metabolic rates of the corals residing there. The metabolism of three coral species from different habitats have been examined to elucidate the effects of these environmental parameters on metabolism, an under-studied aspect of coral biology. For all three species, measurements of oxygen uptake, ammonium excretion, and activity of the enzymes lactate dehydrogenase (LDH), malate dehydrogenase (MDH), and citrate synthase (CS) were used to characterize their metabolism. Off Florida's Gulf coast, Cladocora arbuscula is known to be one of the species least damaged by bleaching events and is one of the quickest to recover, making it an ideal candidate for studying the effects of symbionts. The first set of experiments was designed to reveal the effect of disrupting the coral-algal symbiosis between this subtropical shallow-water coral and its dinoflagellate symbiont, Symbiodinium. The metabolic effects were described for "normal" C. arbuscula and those "bleached" by being held in total darkness for 4 months. Normal C. arbuscula had a relatively low rate of oxygen consumption at 21°C, averaging 2.43±0.65 µmol O2 gwm-1 h-1 (±S.E.), using tissue wet mass, while the bleached colonies had an average rate of 2.46±0.49 µmol O2 gwm-1 h-1. Ammonium excretion averaged 0.07±0.02 and 0.10±0.03 µmol NH4+ gwm-1 h-1 (±S.E.) for normal and bleached C. arbuscula, respectively. The activity values of the metabolic enzymes citrate synthase (CS) fell within the normal range expected for a cnidarian, averaging around 0.09±0.02 activity units (U) gwm-1 for both treatments, indicating normal aerobic ability. MDH was extremely high for the normal corals, compared to other cnidarians, averaging 2.5±0.4 U gwm-1, and a bit lower for the bleached corals, averaging 1.2±0.3 U gwm-1, indicating high MDH activity during both normoxia and hypoxia. LDH ...