I am excited to share what I have been up to for the past 3 months working in Panama at the Smithsonian Tropical Research Institute!
In order to do this, I will first lay out the basics of coral reef ecosystems.
What are Corals and Why are they Important?
Many of you have probably seen a coral reef in a David Attenborough documentary, or if you're like me you have had the pleasure of scuba diving and getting to witness these colourful underwater cities first hand. Coral reefs are incredibly important marine ecosystems often referred to as the 'rainforests of the sea'. They create a 3D nutrient-rich environment in the otherwise nutrient-poor waters of the tropics and thereby form the basis of extensive marine ecosystems. For example, the Great Barrier Reef is estimated to support 1,500 fish species, 4,000 mollusc species and six of the worlds seven species of sea turtles.
Beyond supporting marine life, coral reefs provide important direct benefits to humans. It is estimated that 500 million people depends on coral reefs for protein, income and coastal defence. In fact, coral reefs can reduce wave energy by up to 97%, thereby forming a crucial natural protection for coastlines threatened by storms and tsunamis. Scientists have also extracted unique biological compounds from corals that have been used to create treatments for asthma, cancer and heart disease!
Now that we understand how important these ecosystems are lets look a little bit more at the unique biology of these species.
Many people do not know that corals are actually not plants but animals that permanently attach themselves to the seabed Most structures that we would refer to as corals are in fact composed of thousands of tiny animals called polyps. Polyps form a hard limestone outer skeleton that attaches either to hard substrates on the seabed or to other polyps. In this way, thousands of polyps stick together to form coral colonies of various shapes and sizes.
Now if all this isn't crazy enough, corals represent one of the oldest mutually beneficial relationships between plant and animal life (a symbiosis). Coral polyps host microscopic algae called zooxanthellae within their tissues. These algae provide the coral with energy through photosynthesis whilst the coral cells provide the algae with organic nutrients and protection. Working together, this clever partnership has endured for over 25 million reefs and has allowed coral reefs to grow into some of the largest living structures on the planet!
Climate Change and Coral Reefs
As many people know, the structure of our current global economy is leading to an overproduction of harmful greenhouse gases which accumulate in the atmosphere. Within the ocean one of the most harmful impacts of climate change is an increase in sea surface temperatures, as well as the occurrence of more frequent and more intensive marine heat waves.
Rising ocean temperatures have a detrimental effect on corals, as they cause coral cells to become stressed and therefore to expel the symbiotic zooxanthellae from their cells. Without these photosynthetic algae corals are not able to obtain sufficient energy to survive and die. This phenomenon is referred to as "coral bleaching" as coral colonies become white when they loose their photosynthetic zooxanthellae.
Due to the intensity and speed of rising ocean temperatures most corals are not adapting to rising ocean temperatures quickly enough to evolve resistance. According to the IPCC, under current predicted climate change scenarios, almost all coral reefs are threatened by extinction in the upcoming decades.
Taking Action
It goes without saying that the most needed action to address coral bleaching is addressing climate change and drastically decreasing global greenhouse gas emissions. Unfortunately, even if we act on climate change in a timely manner, due to past and current greenhouse gas emissions ocean temperatures will continue to increase into the future. This has lead marine biologists to asking - is there any way that we can make corals more resilient in the face of climate change?
One of the solutions proposed to achieve this are coral superfoods. Throughout the years humans have faced nutritional deficiencies due to poor diets and so we have invented "superfoods", such as rice enriched with Vitamin C, to improve our health. Just like humans, corals need a little boost to their health to make them better able to resist environmental stressors!
Now although corals mainly obtain energy through photosynthesis they are also able to feed directly on small animals found in the water around them, such as the Artemia pictured below, from which they gain important nutrients.
The project that I joined at the Smithsonian Tropical Research Institute is testing wether feeding corals artemia enriched with vitamins and antioxidants can increase their resilience to heat stress. These "superfoods" are thought to help corals better resist bleaching when exposed to a heat wave as they are packed full of compounds which are important for coral health but which are unfortunately often lacking from coral diets due to nutritional deficiencies in the locations where they grow.
Laboratory studies conducted at the Smithsonian have shown that corals that have been fed with superfoods were more resilient when exposed to a heat stress than corals that did not receive this feeding. These successful laboratory results are now being tested in the field through a partnership with the NGO Reef Restoration Panama. For several months coral fragments being grown in a coral nursery on the Caribbean coast of Panama have been fed with superfoods. The aim of this experiment is to see if feeding corals grown in a nursery increases their resilience and survival. If so, feeding could prove to be a useful action for coral conservation NGOs to implement within their coral nurseries all over the world - giving corals a nutritional boost before they are out-planted back onto degraded reefs.
Future Steps
I have been collaborating with the Smithsonian and Reef Restoration Panama to collect data to understand the changing health of these 'superfed' corals throughout the severe heat waves occurring across the Caribbean over the past several months.
This includes diving to measure variables such as coral growth and photosynthetic activity. I have also been analysying samples in the laboratory to understand their protein, chlorophyll and zooxanthellae content.
With this experience I am now beginning to implement my own project. Over two weeks I will be giving superfoods to corals that are partially bleached within a coral nursery in Portobelo, Panama. The aim I have with this work is to understand whether supplemental feeding can be used by coral conservation NGOs as an "emergency method" to try to save corals that have already begun to bleach within their nurseries.
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