By Sodavy Ou
Over the years, scientists have released countless research results demonstrating the detrimental impacts of increased temperature and atmospheric CO2 on coral reefs that serve as important habitats to numerous marine organisms. These scientific results show that there is much to be done if the international community wants to avoid a 2° C or a 35.6° F increase in the Earth temperature—a threshold at which global warming is irreversible. Already, we have seen major declines in coral coverage in numerous parts of the oceans. For instance, scientists have recorded major declines in coral coverages in the Great Barrier Reef due to increased temperatures and ocean acidification, a process that results from increased atmospheric CO2. However, among these disheartening stories there are a few encouraging stories of corals adapting to the effects of global warming. The telling of these stories, however few, is important in order to fuel and continue the efforts to mitigate the effects of global warming.
In the beautiful waters of Florida, global warming has caused populations of Staghorn coral—once found widely throughout South Florida and the Caribbean—to rapidly decrease. In fact, only 2% of the original Staghorn coral population remains in the Florida Reef Tract. However, a study from the University of Miami’s Rosenstiel School of Marine and Atmospheric Science demonstrates that Staghorn corals can withstand decalcification and increasing ocean temperatures when dietary supplements—made of dried zooplankton power—are provided. This supplemental diet increases coral feeding rates, allowing coral to store more energy reserves and mitigate the detrimental effects of ocean acidification and increased temperatures. The results of this study can be implemented into the management of marine protected areas where Staghorn corals are abundant in order to effectively manage this important population of coral reef.
Another study by the ARC Centre of Excellence in Coral Reef Studies also demonstrates that Staghorn corals are capable of adapting to ocean acidification. This study found that over a relative short period—approximately 9 days—juvenile Staghorn corals can acclimate to a doubling of atmospheric CO2 level and can re-adjust their gene expression to pre-exposure levels. However, this study only tested one stressor, ocean acidification. Still, it is refreshing to know that some corals are capable of adapting to some of the changing ocean conditions.
Coral reefs are ecosystems that provide refuge for numerous marine organisms. Yet a recent study by the US Geological Survey shows that corals are seeking refuge themselves to escape the negative impacts of rapidly changing ocean conditions. The study found more than 30 species of corals have found refuge within the red mangroves of the US Virgin Islands. Mangroves are subtropical and tropical tresses that inhabit coastlines and brackish waters. The root systems of mangroves extend toward the seafloor. These systems serve as a perfect sanctuary for corals by providing them with shade from high levels of solar radiation and coral bleaching. In addition, mangroves keep acidity in the surrounding waters below harmful levels, allowing corals to grow on and under their root systems.
Despite these encouraging studies, there are some species of coral that are struggling to survive as the oceans become more acidic and warmer. The composition of the world coral reefs may look very different in the future. Nevertheless, since corals provide important habitats to countless marine organisms, it is promising to know that some of these corals can continue to serve our oceans. In the end, these promising results will only remain if we continue to address global warming with innovative plans and actions.
Sodavy Ou was born in Cambodia and grew up in southern California. She received her BA in Environmental Studies with an emphasis in Biology at UC Santa Cruz. She will be starting her Master’s Program in Environmental Science and Management at the Bren School at UC Santa Barbara. She spent more than half of her life living by the coast; it’s only natural that she is a lover of the outdoors.