Think of coral reefs as marine rainforests that house and nurture at least 25 percent of the planet’s marine species. Over the past three decades as much as one-quarter of the world’s live coral has been lost. When corals are stressed by changes in conditions such as temperature, light, or nutrients, they expel the symbiotic algae living in their tissues, causing them to turn completely white. This is called coral bleaching. Mass bleaching of coral has been driven by ocean warming. When a coral bleaches, it is not dead. Corals can survive bleaching, but they are under more stress and at risk of mortality.
Many of us have heard about mass bleaching of Australia’s Great Barrier Reef, that has killed more than 30 percent of the reef’s shallow water corals, and mass bleaching in the Indian Ocean and its Seychelles. But researchers are warning that warming ocean waters in the Pacific could spell disaster for coral reefs along the southwest coastline of Hawaii’s Big Island. There are growing concerns the marine heat wave could be even worse than the catastrophic event in 2015 that killed nearly half of the coral along the Big Island’s coastline. Still recovering and thus more susceptible to thermal stress, record ocean temperatures around Hawaii in 2019 are increasing that stress.
What can tourists do and not do? The National Oceanic and Atmospheric Administration (NOAA) is advising both tourists and locals to: avoid killing parrotfish, surgeonfish and other herbivores that eat the algae that can cover and kill corals; use reef-safe sunscreen; keep anchors away from reefs; dispose of chemicals like fertilizers and oils properly; and certainly do not stand on any reef.
As for sunscreens, be aware that some sunscreens include chemicals that destroy coral. Researchers at the Polytechnic University of Marche in Italy published a study recently that estimated that 4,000 to 6,000 metric tons of sunscreen wash off swimmers annually in oceans worldwide and that up to 10 percent of coral reefs are threatened by sunscreen-induced bleaching. Chemicals in sunscreen can also be toxic to fish. Protect fragile reef ecosystems by avoiding sunscreens that contain four ingredients that have been linked to coral bleaching: oxybenzone, butylparaben, octinoxate and 4-methylbenzylidine camphor. In addition, apply sunscreen about 15 minutes before you head into the ocean so the sunscreen has a chance to soak in.
Enjoy what the sea-world in Hawaii offers and do your best to protect that marvelous sea-world, too.