Coral reefs are one of the most vulnerable ecosystems to climate change and other environmental threats. According to UN reports, half of the world's coral reefs have already been lost, posing a serious threat to marine biodiversity and numerous ecosystem services on which we depend.
These ecosystems are key to filtering and cleaning marine waters, as well as providing refuge for many species. Unfortunately, almost a third of commercial fish stocks are being exploited at unsustainable levels. This affects not only marine biodiversity, but also millions of people who depend on marine resources for their livelihoods.
Increase in fishing and consumption
At the UN Environment Assembly (UNEA-3) in Nairobi, it was highlighted that factors such as overfishing, extractive activities, tourism, coastal development and pollution are accelerating the destruction of marine habitats. This leads to a drastic reduction in the populations of marine species, bringing several species to the brink of extinction.
Unfortunately, although the goal was to protect 10% of coastal areas and territorial waters by 2020, the reality is that to date only 14,4% has been protected, which highlights the need for more effective management and a balanced distribution of the costs and benefits derived from the protection of these ecosystems.
Increase marine protected areas
When it comes to the decision to protect a marine area, two main positions emerge. On the one hand, there are those who seek to improve the conservation of biodiversity and ecosystems. On the other hand, there are those who fear that doing so could mean a loss of economic and social benefits, mainly for coastal communities that depend on fishing, tourism and other activities linked to the sea.
However, according to the report 'Frontiers', presented at UNEA-3, it is highlighted that managing the oceans sustainably, by increasing the number of marine protected areas, can act as an "engine" to boost the economy. This is because proper management and conservation of the seas can promote long-term economic growth, protecting resources that are essential for many coastal industries such as tourism or sustainable fishing.
Threats to coral reefs
There are both local and global threats that are significantly affecting coral reefs. At the local level, reef destruction is mainly due to human activities such as coastal development, destructive fishing or irresponsible tourism. These activities not only physically damage reefs, but also contribute to sedimentation and pollution that aggravate the situation.
Common local threats include:
- Physical destruction: The construction of infrastructure, ports, dynamite fishing and the use of destructive nets are some of the activities that seriously damage reefs.
- Contamination: From land-based pollutants such as fertilizers, pesticides, industrial and household waste, to marine litter, the situation is critical. Pollution causes an excess of nutrients that leads to uncontrolled algae growth, preventing corals from receiving enough sunlight.
- Overfishing: The reduction of species essential to reef ecosystems, such as grazing fish, upsets the balance of the food web, allowing the proliferation of algae and other organisms that compete with corals.
- Coral extraction: The harvesting of corals for jewelry and decoration also contributes to the disappearance of reefs.
Global threats: Climate change and ocean acidification
The most important problem facing coral reefs is climate change. Rising ocean temperatures are causing mass coral bleaching. This phenomenon occurs when corals, under thermal stress, expel the symbiotic algae that provide them with nutrients and their characteristic color. Without the algae, corals become weakened, lose their color, and if the process continues, they may die.
Ocean acidification is another key factor threatening coral reefs. As carbon dioxide (CO2) levels in the atmosphere increase, the oceans absorb more of this gas, producing carbonic acid. This lowers the pH of seawater, making conditions less favorable for corals to calcify, making it harder for them to form their calcium carbonate skeletons.
Economic and social impact of reef loss
The disappearance of coral reefs has a direct impact on coastal communities that rely on them for their livelihoods. It is estimated that hundreds of millions of people depend on reefs for food, income from tourism, fishing, and protection from storms and tsunamis.
For example, in the Mesoamerican region, which is home to one of the world’s largest coral reefs, reef-related activity generates revenues of US$6200 billion each year. If reefs continue to disappear, this figure is expected to drop by half in the next decade. However, if appropriate measures are taken to restore them, it could increase to US$8700 billion annually by 2030.
Coral reefs are also a crucial source for biomedical research. Many reef-dwelling species possess properties that are being investigated for the treatment of diseases such as cancer.
How can we save coral reefs?
Although the situation is critical, there is still hope for coral reefs if urgent and effective measures are taken. Some of the steps that can be taken include:
- Emission reduction: The main cause of global warming is greenhouse gas emissions. Reducing these emissions is crucial to stabilise ocean temperatures and mitigate coral bleaching.
- Protection of marine areas: There are initiatives that seek to increase marine protected areas, limiting destructive activities such as fishing and invasive tourism.
- Reef Restoration: In some areas, reef restoration projects are being carried out by planting new corals, although these projects are often expensive and require sustained effort.
- Contaminant reduction: Regulating chemicals, plastics and other waste that end up in the oceans is essential to improve water quality and provide better conditions for reefs.
Despite the serious threats they face, coral reefs have shown a surprising ability to recover, especially when pressure on their ecosystems is reduced. If we take action globally, helping to reduce the impact of climate change and sustainably managing marine resources, we could see reefs restored within the next decade.