By Chuck Dayton
Minnesota conservationist Chuck Dayton reports from a two and a half-month research trip in the Central South Pacific to understand and bear witness to the impact of climate change and sea level rise on local populations and coral reefs.
What are the most beautiful and wondrously complex ecosystems on the planet? Rainforests? Prairies? The Boreal forest lake country?
For anyone who has spent time underwater on a healthy coral reef, the answer has to include those amazing and enchanted ancient underwater gardens. Like rainforests, they are diverse beyond our current knowledge. They occupy only one percent of the Earth’s sea floor, but contain some nine million species, and a quarter of all marine fish species, and they may also hold potential for new medicines.
Reef fish are among the most exquisite creatures evolution has produced, their brilliant colors parade in an unending symphony of forms and patterns. To float motionless and watch the interrelated dance of these unfamiliar life forms is a spiritual experience (my poem about that is at the end of this piece). The coral colonies themselves, collections of minute animals that build reefs through their own skeletons, with the ability to incorporate tiny algae inside their own cells to photosynthesize their food, are one of the great wonders of life. And then there are the sponges, the urchins, the flowerlike tubeworms, anemones and the occasional moray eel, shark, octopus, squid, manta ray, sting ray and so on and so on.
It was the love of reefs and the threats to these living treasures (and a seminal book describing reef decline, Coral Reefs in the Microbial Seas by Forest Rowher, which is the basis for the scientific information presented here unless otherwise noted) that helped to inspire my hosts to buy their research sailing vessel so they could study reefs through diving surveys.
We are sailing west across the Pacific on the Research Vessel Llyr, (named for a Welsh sea god) a 53-foot ketch sailboat, on a two-fold mission for 2013. The first part is diving surveys to document the health of coral reefs for Reef Check, a citizen science program for reef monitoring worldwide. Another important part of this mission is to observe, document and analyze social and economic changes from such environmental insults as climate change and overfishing as they impact coastal communities and coral reefs.
Brooks McCutchen, a former psychoanalyst and Janis Steele, a PhD. anthropologist and documentary filmmaker, spend a little over half of each year as maple syrup farmers in the Berkshires of western Massachusetts. As social scientists, they focus on the cultural politics and economics of small-scale, sustainable food production and marketing, as well as coral reefs. Their three sons, Connor, 18 (the First Mate), Rowan 15, and Gavin 10, are a vital part of the project. Their 2013 expedition voyage started from Panama in late April, and I joined the boat in the Marquesas a month later, after they had endured some 4,000 miles of open ocean sailing in fairly heavy waves and winds. (In 2012, Llyr and crew traveled from Massachusetts to Panama, working on surveys and social science research in Dominican Republic, Haiti, Costa Rica and Panama. Next year, Llyr may become a service vessel in Vanuatu, working with local communities interested in sustaining bio cultural diversity through uniting traditional ecological knowledge with scientific knowledge.)
The beautiful and mountainous Marquesas Islands don’t have a lot of reefs, so we did our first reef surveys in the Tuamotu islands, low-lying coral atolls, where the original volcanoes have sunk, leaving the lagoon-encircling reefs. The Tuamotus do not have a large human population, and the reefs appear to be in pretty good shape. We saw big schools of snapper, barracuda, dolphins, healthy corals, moray eels, lots of butterfly fish and angelfish, and sharks, the latter being a good indication of a healthy reef.
Sailing on to Tahiti, we were unprepared for what we found. We knew that the reefs at Tahiti, especially near the capitol of Papeete had been damaged by nutrient pollution and overfishing, but they were worse than we had imagined: the coral was gone, and had been replaced by algae, or just bare rubble. There were still a few fish and a few sharks, and that was the meager fare that the dive operators had left to offer to tourists. The contrast with the healthier reefs in the Tuamotus was striking. The dive operators blamed runoff from local construction projects, but it was obvious that there is something else at work.
Oh well, we thought, things will be much better in Moorea, especially in the vicinity of the magnificent and mountainous rural bay where we planned to anchor, away from a concentration of people. The cruising guidebooks and even the Lonely Planet extolled the beauty of the reefs there. But, OMG! Same thing: dead reefs. We found mostly just rock and algae and a few fish; other cruisers confirmed that to be true of the entire island.
We sailed west to Huahine Island where cruising sailors a couple of years ago had found “the best snorkeling in French Polynesia” and then to Raiatea, but coral near these islands is not much better: a little more live coral, a few more small fish but mostly algae and rock, the dead remains of once-vital corals.
The conversation on Llyr is an ongoing seminar about coral and the problems of coral reefs, as well as the economics and politics of small scale vs. large scale food production and distribution. Janis and Brooks are fairly knowledgeable about reefs and critically read and discuss the latest scientific literature.
Our reasonably well informed understanding is that the stressors to coral reefs are primarily human caused, and are both global and local. The global threats are rising sea temperature and ocean acidification. The local threats are overfishing, nutrient pollution and in some areas the Crown of Thorns starfish. We are under water almost every day, and to witness the loss of this magnificent resource is heart-breaking.
Increased sea temperatures as the planet warms causes damage to reefs. This phenomenon is well documented and studied. Coral incorporate microscopic algae, (one million per cubic centimeter) called Zooxanthellae, into their polyps, which photosynthesize sunlight, CO2, and nitrogen from the coral into food and oxygen. The coral use these to survive and to make protective mucus on their surface to repel pathogens. If the maximum water temperature goes about two degrees C above normal for one week, the coral expels the Zooxanthelae, turns white or bleaches, and usually dies within a few weeks. (When the temperature rises, Zooxanthellae are expelled by the coral, maybe because with an excess of CO2 they produce more oxygen and the coral immune system then kicks them out. We don’t know why for sure but we do know that warming causes bleaching. Fifty percent of the Great Barrier Reef of Australia has lost its coral from several vectors including bleaching due to temperature increase.) Bleaching makes disease from pathogens more likely.
In Moorea, we spent two and a half hours talking with scientific researchers at the well-funded French Marine Research Station. They have installed monitoring buoys around French Polynesia that measure temperature, PH and nutrients levels. They found that the average sea temperature increase over the last ten years has been one third of a degree centigrade. That’s .6 degrees F, much faster than the air is warming globally. If that rate were to continue long term, in 100 years that would be an increase of 3.33 degrees C or about six degrees F, much higher than two degrees C necessary to wipe out most of the coral. Maybe the warming will be less, but it also could be higher, and sooner, if tipping points are reached.
Ocean acidification is the other big global threat. Oceans are a huge sink for CO2. As CO2 levels increase in the atmosphere, the oceans absorb more and more. About a third of the carbon dioxide emitted by human activity is absorbed by seawater. The increased CO2 makes the sea water more acidic and reduces the carbonate ions which are utilized by the coral to construct their skeletons, as well as by other marine organisms which build shells, or help cement the reefs. The projection is that by century’s end is that coral calcification rates will be reduced by 40 to 60 percent.
Overfishing and nutrient pollution, both local human impacts, also have a huge impact on coral reefs. The reasons are complex and were only recently discovered. Algae produce Dissolved Organic Carbon (DOC). On a healthy reef, many fish eat algae, keeping them in check. When too many of these herbivores (the algae-eating fish) are removed by overfishing, more algae grow, producing more DOC. That additional DOC stimulates the growth of more microbes than are normal. These excess microbes literally suffocate the coral by using up the oxygen on their surfaces, which has been provided by their Zooxanthellae.
Nutrients (sewage, fertilizers, construction sediment) have a related effect; they stimulate the growth of algae, which causes more DOCS, which produces more microbes, which suffocate the coral. There is also a feedback loop operating here: as more algae are produced, more coral dies making more room for algae.
The crown of thorns starfish devastated Moorea and other nearby reefs in 2007, and that was followed by a severe tropical cyclone in 2010. The reefs were just dead in many places. In some areas, we snorkeled over colonies of small coral colonies that are beginning to reestablish, but in others where algal growth has taken over, the coral is not coming back. Those totally dead and algal covered sites are where the nutrients from local sewage and runoff from agricultural production (like Pineapples) is more likely to be located. Algae here are not all like the green slime we know. They are more like plastic flowers, and some algae are beneficial, laying the groundwork for more coral.
The cautious scientists at the research station said they aren’t sure what caused the crown of thorns invasion, but then they proceeded to present good arguments that the crown of thorns invasion is exacerbated by human causes. (The Crown of Thorns starfish is indigenous, but five years ago its population exploded in this archipelago. Why? One explanation is that nutrient levels from humans — sewage and fertilizer for the pineapple plantations — combine to favor Crown of Thorns larvae, which are born in deeper water, while coral are hindered by both temperature and nutrient increases. We also know that increased water temperatures favor algae and disfavor coral, so the larvae of the Crown of Thorns may thrive better because they eat algae until they reach about five centimeters, and then switch to munching coral. To me this is analogous to the devastation caused by the Pine Bark Beetle in the American West, an exploding population of an indigenous pest that humans have unwittingly aided.)
So, what then must we do? Current evidence seems to forecast that the reefs are doomed by temperature increase and acidification in the long run if we cannot solve the climate crisis soon enough. Obviously we need to address that in all the ways that we can. Whether there will be enough coral and related reef organisms like reef microbes left on the planet ultimately to reestablish, when and if the sea temperatures are back in a normal range, is an unanswered question. If not, we will be the first species to eliminate an entire planetary ecosystem. (Being aware of these threats, I wanted to make sure that my kids and grandkids had a chance to learn diving. If you are inclined to do that, do it soon.)
While most actions to prevent the local stressors of coral must be taken by governments, establishment and enforcement of fishing treaties and marine protection areas, sewage treatment, for example. Individuals can be careful about the kinds of fish they buy, and choose those that are fished in an environmentally responsible manner. One organization that certifies fishing operations reliably is Marine Stewardship Council, formed in the UK.
I wrote this poem in 2006 after reading about the large temperature-induced bleaching die off of that year. I didn’t see that, but having seen the dead reefs here, it takes on new weight for me:
“It’s an unprecedented die off,” said National Park Service biologist Jeff Miller. “We’re talking colonies that were here when Columbus came by have died in the past 3 to 4 months.” -AP, March 31, 2006
Drift down gently with me, down
Below our silver bubble mantras, down
Beneath the ocean’s skin, rippling
Like a well-muscled torso. Slide down
Sunlight shafts, through liquid crystal, down
To the brilliant blue edge of the abyss,
Past coral castles, giant brains, antlers, fans,
Masterpieces of countless coral generations.
Fields of animal flowers,
Swaying in the oceans pulse
Are the stages for the endless parade
Of exquisite colors, gliding, cruising,
pecking, chasing. An indigo cloud of tiny fish
Reflexes from my hand, follows, flashes again.
Dare to look down into the infinite royal blue.
Where toothy mouths, real and imagined, wait.
A small spiny creature wiggled out
Onto a muddy shore, and became, countless
Generations of coral later, an upright animal
Burning the sunlight trapped by ancient life.
Its smoke blankets the planet,
heating the oceans,
bleaching the coral.
The fecund web collapses, and
This cradle of all life lies empty,
White as death, in relentless sun.