PAM values and coral physiological measures in response to DIN treatments from 2015-07-01 to 2016-01-30 (NCEI Accession 0145017)

The scope of the proposed work includes a six-month laboratory dose response experiment to determine the effects of environmentally-realistic levels of DIN on coral health and function. Plugs or branch tips of four species of Atlantic scleractinian corals, Porites astreoides, Porites divaricata, Montastraea cavernosa, and Siderastrea siderea were exposed for six months to five concentrations of nitrate. Four independent replicates of each elevated nitrogen concentration was maintained by addition of a nitrate solution to dose water. To link coral physiological performance to exposure over time, the maximum quantum yield of PSII photochemistry of each coral was monitored bi monthly with a submersible pulse amplitude modulated fluorometer (PAM). To assess growth rate and calcification response, buoyant weight measurements will be utilized. To quantify tissue condition, and zooxanthellar density, 25% of each coral was fixed for histological analysis at the end of the experimental period. These metrics are used to identify cause and effect relationships and specific responses associated with quantified levels of nitrate.