Coral reefs—known as the rainforests of the sea and considered one of the most diverse ecosystems on Earth—have long been heralded for their diversity and importance in marine ecosystem function and ecosystem services. With their stunning beauty, these colorful underwater kingdoms perform an array of ecosystem services, from housing a rich tapestry of marine life to protecting coastlines from erosion.
But coral reefs have confronted serious pressures too, notably in recent decades when the double whammy of climate change and human activity has imperiled their existence. However, conservation on the reefs is now a thriving and rapidly expanding field of study, and as a result, all hope for these biodiverse hotbeds of activity need not be lost.
The Ecological Importance and Biodiversity of Reefs
According to a global study, coral reefs are biodiversity hotspots that represent only less than 1% of the ocean floor but host approximately 25% of all marine species. The reason for this high concentration of species diversity is because the structure of reefs provides food, shelter, and spawning pools for thousands of different types of marine organisms, including fish, invertebrates, and corals themselves. These complex ecosystems support intricate ecological interactions, which in turn have effects on fish populations and ultimately impact the stability of a larger marine ecosystem.
According to a 2018 report, ocean coral reefs in the Indo-Pacific area were proven to benefit around 70% of fish species at some point during their development. This relationship is an illustration of the importance of coral reefs to marine biodiversity as a whole.
Projections for the future also predict that declines in coral habitats will translate into a decrease of up to 30% in local fish populations throughout this century if effective management is not implemented. Projected changes like these highlight the importance of further action in reef conservation efforts if we wish to conserve marine biodiversity and protect the invaluable ecosystem services to humanity that coral reefs provide.
Future Prospectus: By 2050, sufficient reef management is expected to conserve 60% of the world’s coral reef habitats, which will inherit fish populations and improve the ecological resilience of coral reefs.
Climate Change and Coral Bleaching’s Role in Reef Ecosystems
Coral bleaching—when corals look white because they have expelled the algae living within their tissues due to stress from high sea temperatures—is one of the most dramatic and immediate problems produced by climate change on coral reefs.
Such a process would deprive corals of both their colorful hue and primary food source, the latter leading to disease and death. In recent years, four mass coral bleaching events have been logged since the late 1990s—in 1998, 2010, and more recently in April this year (2016), known for the destruction of reef ecosystems worldwide.
For instance, the Great Barrier Reef suffered extreme coral bleaching in 2016, and last year saw nearly 93% of the reef’s corals affected. It was an enormous reef-wide bleaching event, with a knock-on of reductions in species diversity among the animals that lived in these underwater habitats.
Although the ability of corals to recover is high under optimal conditions, the stabilization of warming trends suggests long-term recovery will be limited without further action. If global temperatures rise by 1.5°C above pre-industrial levels, future predictions suggest that more than 90% of coral reefs will be subject to high risk of bleaching before 2040.
Future Projection: Bleaching risks are predicted to decrease by 40% thanks to restoration and climate mitigation strategies that will increase coral reefs’ ability to alkalinize, contributing to increased thermal tolerance if maintained until 2050.
The researchers also found that whether or not healthy reefs recover enough to be self-sustaining in a changing climate will largely depend on global efforts to reduce greenhouse gas emissions and efforts to conserve corals.
Restoration Action Items and Marine Conservation Efforts for Reef Protection
Due to the critical condition of coral reefs, restoration programs have been formulated to restore and conserve these sensitive systems. Coral reef restoration projects such as coral transplantation, artificial reef structures, and assisted coral reproduction are designed to enhance the health of corals and promote recovery.
Coral reef conservation organizations, agencies, and even local communities have been involved in these efforts to help protect coral reefs and help them build resilience.
Case studies such as one conducted by the Florida-based Coral Restoration Foundation in which over 50,000 corals were put back into damaged sections of the Florida Reef Tract between 2015 and 2020 have shown that coral transplantation can be an effective solution.
These fledgling enterprises have been working well, however—one aiming to protect habitat and restore marine life found that 60% of the transplanted corals survived the transplantation. With the ever-tightening grip of technology and capital around our oceans, we can only look forward to the day when an entire reef has been put back together using 3D printing, a singular building block in a larger ultimate plan.
Future Projection: 80% of the damaged coral areas will be restored globally by 2050, which will aid in stabilizing the health of coral ecosystems and rebuilding marine biodiversity.
The Way Forward: Reef Management and Marine Habitat Preservation
Effective reef management and well-enforced marine protected areas are essential to protect these complex ecosystems from the many more local and global pressures they are now experiencing. Research into reef management involves regulation of fishing practices, control of pollution, and enforcement of marine protected areas to limit the human impact on coral ecosystems.
Moreover, habitat protection must be framed in a larger environmental health context; overfishing and coastal development are additional major threats to coral reefs and their associated marine species.
Positive effects of integrating reef management within a wider marine conservation policy have been demonstrated (and even at larger spatial scales such as MPAs, given their on-balance operation in the context relevant to bleaching and storm damage resilience) [47].
In the Seychelles, for example, a reef management plan introduced in 2014 that increased the extent of protected areas by 30% has led to a major improvement in coral health. With an increasing number of countries employing such tactics, reef management may hold the key to ensuring the survival and recovery of coral species and the biodiversity dependent on them.
Future Outlook: Improved reef management is projected to reach 90% of the planet’s reefs by 2050, protecting coral ecosystems from the impacts of a changing climate.
