The Newly Discovered Amazon Reef is Already Under Threat

One of the most exciting aspects of our blue planet is that we still have so much of it left to explore. We are still leading exploratory expeditions deep under the waves which are uncovering never before seen creatures and complex ecosystems we had no idea existed. One of the most recent and surprising discoveries has been a unique coral reef lying at the mouth of the Amazon River, making this area even richer in biodiversity than we first thought. Yet not long after this new world wonder was found, its existence became threatened by human activity.

Scientists first stumbled across this hidden marine habitat in 2012 and since then, several exploratory studies have taken place, with the reef proving to be much larger and much more diverse than scientists expected; in fact, they never believed a reef could even form in such an extreme environment. The Amazon reef defies what we thought we knew about corals as, due to its location at the mouth of the world’s largest river, this area receives an enormous amount of sediment each day in the form of mud and sand, making the water incredibly murky. This was thought to prevent the growth of coral which needs sunlight to grow. However, this unique reef is comprised of hard red algae which has adapted to low light conditions. Unlike most species of coral which sunbathe in shallow clear waters, these use the blue spectrum of light to gain enough sunlight to be able to photosynthesise and grow in relatively dark conditions. The river surges also result in the local water chemistry and salinity changing much more dramatically than on normal reefs, meaning the species here are forced to be both hardy and adaptable. The reef must also contend with the strong river currents which would damage other coral species whilst additionally battling against low oxygen conditions and surviving in deep water. All these factors have made studying the area incredibly difficult as turbulent, murky waters are far from ideal working conditions for boats, divers and remotely operated vehicles. Unlike most reefs, this one dwells in deep water, lying between 60 and 220 metres below the surface, providing yet another challenge for researchers.

Despite the odds however, the Amazon reef has flourished and covers an astonishing 22,000 square miles, curving alongside the coast of Brazil. Initially, researchers assumed it would hold very little life due to the unfavourable conditions but already they have discovered 70 species of fish, including bright schools of angelfish, wrasse and parrotfish. The reef is also home to many sponges, including 29 new species never seen before and one sponge specimen weighing the same as a baby elephant! There are larger species too, such as the wonderfully named melon-headed dolphins and pygmy killer whales. Some of these mammals reside in the area permanently whilst others pass through on their long migrations, taking a rest at this reef buzzing with life. A corridor has been spotted winding through the reef which is thought to allow fish to make the journey between the Caribbean and Southern Brazil, perhaps explaining why diversity is high here. Yet another theory suggests it is the mud which is boosting biodiversity due to its high nutrient and microbe content. Whilst most reefs around the world are falling into poor health, the Amazon reef is showing no signs of bleaching and appears in pristine condition with each crack and crevice in its walls home to a brightly coloured creature, many of which are yet to be identified and are believed to live only in this region. In fact, scientists are eager to explore the plants and animals on this reef as they believe there may be species with potential medicinal or scientific value and already, one new sponge is being tested for potential anti-cancer properties. Excitingly, researchers believe this area has equal levels of biodiversity as the famous Great Barrier Reef and have announced it as a significant ecological community.

Sadly however, this wonder of our blue planet is already under threat despite surviving thousands of years without us knowing about it. Over the last several years, a couple of oil companies have expressed interest in deep sea drilling off the coast of Brazil in an area extremely close to the reef. Whilst no drilling has yet begun, recent offshore oil discoveries in nearby Guyana and Suriname have put the pressure on Brazil to further explore their potential resources. This has led to exploratory drilling in the ocean near the mouth of the Amazon. Scientists, conservation groups and local communities have one large concern surrounding this new enterprise; what will happen if there is an oil spill? With some of the strongest currents on the planet and astounding ten metre tides, any oil spilled in this area will be quickly swept away and dispersed, making a clean-up operation difficult, especially since we do not yet know whether remotely operated vehicles will be able to work in the turbulent waters.

The impact of an oil spill on coral reefs depends very much on the exact conditions, meaning that detailed modelling would need to take place to assess the potential environmental damage of oil drilling here. As oil is a complex mix of chemicals, it can quickly kill some coral species by inhibiting coral reproduction and growth. This is especially problematic if the oil spill occurs at the time of year when corals spawn, an incredible synchronised event that sees all the corals on a reef reproduce on the same night of the year. However, even low levels of oil have been found to be deadly to some corals if they are exposed for a prolonged period of time. This could occur simply from the day to day running of oil rigs as small amounts of oil are lost from the rigs, drills and associated vessels. Once oil has entered the tissues of corals, it is slow to depart which means that the toxic effects can continue long after the spill. In fact, petroleum hydrocarbons from oil actually become deposits in the exoskeletons of coral, forming rings throughout their structure. This means that when cut open, corals can actually show a historical record of when high levels of hydrocarbons have been in the water, indicating an oil spill at that time in their life.

Yet it is not just the corals themselves that would be affected by a spill but all the animal species which live in and migrate to the reef too. For those fish which live on the reef, this could be a large problem as they don’t have the choice to move on and migrate to a cleaner patch of the sea. Creatures such as turtles and dolphins can be especially at risk as they must surface to breathe and will therefore have to break through the oil slick which often lies on the top layer of the ocean. Close to the newly discovered reef is the Cabo Orange national park, home to protected species such as the Amazon manatee and small tooth swordfish, all of which are also put at risk of both oil and noise pollution if drilling takes place.

If an oil spill is carried towards the coast due to the currents, it will also affect mangrove forests, an incredibly important ecosystem home to a range of species from birds to crocodiles, giant otters to turtles. These wetland woodlands are filled with tangled twisted roots which get covered by the tide each day, yet these sweeping tides can also carry in oil. Often, it is the outer edge of the forest worst affected as their roots become coated in thick oil. These trees have adapted to breathe via lenticels on exposed roots but once these are clogged with oil, the plants struggle to respire properly and often defoliate or die altogether. This leaves the coastline open to erosion whilst the loss of leaves allows more sunlight to reach the forest floor, leading to higher temperatures. Whilst these unique ecosystems are important for wildlife, they are also essential in our fight against climate change as these forests are surprisingly twice as carbon rich as the famous rainforests found further inland.

The clean up of an oil spill in this area would be incredibly difficult. The strong currents around the river mouth mean remotely operated vehicles may not be able to operate to help cap a deep water blowout whilst mechanical methods could damage the reef further. The initial plan from interested oil companies based their clean-up operation on the use of a chemical dispersant called Corexit but scientists have highlighted this could be even more hazardous to corals than the oil itself. If drilling is to go ahead, it is clear we need many more answers first.

Thankfully, there appears to be a lot of apprehension around the oil plans. Drilling licences were refused by the Brazilian government in 2018, largely thanks to the tireless work of Greenpeace who were involved in the initial discovery of the Amazon reef. 200 volunteers helped them disrupt a meeting held by the relevant oil company in Paris by parading a samba carnival through the building whilst climbers abseiled down from the ceiling with protest banners. Unfortunately however, the threat is back, with oil companies more determined than ever to find new reserves. The local community appear divided, with some believing oil exploration will lead to more jobs and cheaper energy whilst others believe it will drive away the fish they rely on for income and worry of the consequences of an oil spill. This is a widespread concern on the coast of Brazil as a crude oil spill in 2019 left beaches black and sticky, destroying their tourism season and causing the local fish market to plummet by 80% due to fears of contamination. With a new government in place, no one is quite sure how Brazil will proceed as the new licence hangs in the balance. The UN has declared 2021-2030 the decade of ecosystem restoration, with coral reef protection at the centre of its strategy to fight the climate crisis, increase food security and enhance biodiversity. Oil can’t deliver on any of these goals but the newly discovered Amazon reef just might, with the added bonus of potential new medicines.

By Neve McCracken-Heywood