Galapagos Coral: Current Conditions and Future Threats
If you've ever strapped on some flippers, facemask and donned a wetsuit, then you've probably seen one of the world's most incredible underwater wonders – coral. These colorful sanctuaries of marine life are home to some of the most diverse ecosystems on the planet, with life ranging from microscopic to macroscopic. The Galapagos Islands are renowned as a diver's paradise. But with global temperatures rising, the question looms: Will this mark the end of Galapagos coral reefs?
Do the Galapagos Islands have coral reefs or just coral colonies?
The first thing to understand about the marine ecosystem of the Galapagos Islands is the distinction between a marine environment that has coral colonies and one that is a coral reef. The Galapagos Islands more closely resemble the former.
There are considerable communities of coral that have allowed abundant marine life to establish itself around these colonies, but classical reefs tend not to form due to the Islands' location at the confluence of multiple warm and cold water currents, creating an unstable oceanic environment for such a fragile organism.
Dr. Sandra Brooke, an expert in coral ecosystems from Florida State University, states, "The Galapagos has reef building species, which are too sparsely distributed in some areas to form the traditional reefs; however, this doesn't mean they don't form valuable ecosystems, support diverse communities, and should be managed and conserved as a reef would be."
Marine biologist Genevieve Andersen expands, saying, "Galapagos has coral, although it is unique in that it seems to be unable to reproduce sexually."
Since they can't reproduce sexually*, there is speculation as to how these colonies have become established in the Galapagos Islands. One theory attributes their presence to the warm-water conditions brought by El Niño.
"During extreme El Niños, the Kelvin Wave may bring Australian coral larvae back across the Pacific in warm waters and provide the source for the Galapagos coral heads," explains Andersen. "The coral heads may get started in these severe El Niños but are living marginally in the cold waters of Galapagos and unable to sexually reproduce."
However, ironically, the same phenomenon that Andersen speculates might bring the corals to this region could also be responsible for its devastation – the 1982-83 & 1997-98 El Niño events nearly obliterated coral life in the Galapagos Islands, and the 2015 El Niño promises potentially hazardous conditions as well.
A University of Edinburgh School of Geosciences report states: "The extreme climatic fluctuations under El Niño events in the region are particularly damaging for coral populations - extensive coral reefs were reduced by 97% in 1982-83 and further compounded to 99% losses in 1997-98."
In order for the coral animal to sexually reproduce and therefore establish large enough colonies to be considered a reef, they rely on a symbiotic relationship with zooxanthellae, which provide simple sugars to the corals via photosynthesis. The coral then provides the zooxanthellae with nutrients via its excrement. Simply put, the zooxanthellae provide sugar for the coral and the coral provides nutrients for the zooxanthellae. One cannot survive healthily without the other.
The threat of coral bleaching & the end of reefs
Like any living species, environmental factors influence coral's survival. The lifespan of a coral colony or a coral reef can span thousands of years, but eventually even the greatest reefs are reclaimed by the oceans that first spawned them. Nowadays, the major question is what role we as humans have played in changing the environment to provoke their premature extinction.
Colonies and reefs follow a consistent life cycle: a classical reef will begin as a fringing reef in the shallows of a volcanic island. As the island begins to retreat back into the ocean, the reef will continue to build its walls up, usually at pace with the sinking island, and becomes a barrier reef.
Finally, an atoll forms once the island has sunk below the water but the reef has continued to build upwards. This can also lead to the formation of cays.
Corals are unique in their ability to thrive in warmer, nutrient-poor waters. However, the zooxanthellae, which give the corals their color and more importantly their food, cannot survive in the nutrient-poor waters. Normally, the corals can compensate for this by providing the necessary nutrients; but when water becomes a less suitable environment for the coral, they cannot do this. So when something happens (natural or man-made) to deplete the water of its naturally occurring nutrients or to deprive the zooxanthellae of the sunlight it needs to photosynthesize, they die.
When this happens, "the coral tissues usually become pale – a condition on coral reefs called 'bleaching.' Bleaching events may be due to natural or man – made causes and are a concern worldwide as they are increasing in recent years," according to Andersen.
Brooke states, "The algae (zooxanthellae) normally give the coral a yellow-green color but when they disappear, the white skeleton shows through the transparent coral tissue, and the corals look white or 'bleached'."
Typically, this is a normal event and does not necessarily threaten the life of the coral animal. However, Brooke warns, "the extended bleaching that is being observed more frequently in recent years does cause mortality as the corals cannot live indefinitely without their symbionts, and extended high temperatures can cause direct tissue damage."
This is happening at an alarming rate around the world – in the past 40-50 years alone, scientists have observed startling devastations of Galapagos coral colonies, which could be indicative of what will happen in the rest of the world if conditions continue to deprive the coral of a sustainable ocean environment.
Galapagos coral: A looking glass to the future of global corals
The NOAA explains that the Galapagos Islands are unique in their diversity of ecosystems, which flourish because of the serendipitous convergence of multiple oceanic and atmospheric conditions. This allows scientists to witness and study a living example of conditions that don't exist anywhere else in the world.
One such condition is the high level of carbon dioxide in the water, caused by the upwelling of deep ocean water. This CO2 makes the water more acidic and creates a bad environment for the coral.
According to the article, "Waters with high carbon dioxide can have negative effects on some organisms, like corals, that build their skeletons underwater."
This makes the coral more susceptible to natural events, like hurricanes or the El Niño phenomenon, and threaten its extinction in certain parts of the world. Although this more acidic water occurs naturally in the Galapagos Islands, scientists think it could forecast what might happen in the rest of the world if humans continue to pump such high levels of carbon dioxide into the environment.
Other environmental risk factors include over-fishing, the elimination of mangrove colonies for commercial development, dredging, and contamination, among other environmentally dangerous threats. Many of these threats directly result from human actions, and could spell extinction for these marine ecosystems.
Brooke is not completely pessimistic for the future of reefs, but she says that it will require a level of dedication yet unseen from the global community and especially the lawmakers.
"Biology is remarkably resilient but there are limits. If the damage is just physical and the surrounding ecosystem is healthy, chances are a system will recover," she says. "If, however, there is chronic environmental degradation, a few weedy species may hang on, but the rare and vulnerable will disappear. We need to clean up our messes locally and make the reefs as healthy as possible to help them cope with the effects of climate change."
On an individual level, Brooke says that we can play our part in protecting the reefs by admiring their beauty without touching them when we snorkel and dive, practicing more conscientious consumption (knowing where our fish come from, for example), and practicing environmentally beneficial eco-tourism.
"The Galapagos has a good record of ecotourism," she remarks, "which will hopefully protect the Islands' corals and maintain a healthy marine ecosystem in the face of climate related changes."
All things considered, it stands to reason that if changes aren't made on a global level, the oceans supporting these vibrant reefs will eventually become too exploited and damaged to host them any longer, and the coral (and the rainbow of marine life they are home to) will become a memory of yesteryear.