Sublethal Metabolic Responses of the Hermatypic Coral Madracis decactis Exposed to Drilling Mud Enriched with Ferrochrome Lignosulfonate

摘要

Madracis decactis corals were exposed for 17 days in laboratory aquaria to suspensions of 100 ppm drilling mud spiked with 0, 3, and 10 ppm ferrochrome lignosulfonate (FCLS). During the first week of exposure, these corals increased their oxygen consumption and ammonium excretion, relative to uncontaminated controls. These corals exposed to the highest enrichments of FCLS demonstrated the greatest increases in respiration and excretion and also the largest variations in respiration and excretion between individual experimental animals. Corals reached their highest average rates of respiration and excretion by the end of the first week of continuous exposure. Rates then decreased during the next week and, after a secondary increase in excretion and respiration between days 10-13 which was most pronounced in those corals exposed to FCLS enrichment, leveled off at near-initial rates by the end of the second week. All corals exposed to FCLS reacted by reducing their polyp expansion behavior, although only the two showed mass polyp mortality. When exposure to drill mud + FCLS was discontinued, respiration and excretion of surviving corals remained low and stable while their polyp activity returned to normal levels within 48 hours.