What are Marine Biodiversity Hotspots?

Marine biodiversity hotspots are regions teeming with a high number of species found nowhere else, many of which are endangered. Despite their ecological importance, these areas face significant threats such as habitat loss and degradation, placing them among the highest conservation priorities globally. Although hotspots represent critical strongholds for marine life, they are under mounting pressure from human activity and environmental changes.

Mesoamerica and the Caribbean are two such regions, distinguished by their exceptional biodiversity. The Mesoamerican Barrier Reef System, the second-largest barrier reef system in the world, stretches through this area. Beyond their natural richness, these regions are also home to many Indigenous communities who have long maintained a close and respectful relationship with their environment. Although Mesoamerica covers less than 2% of the Earth’s surface, it harbors 12% of the planet’s biological wealth, supports 8% of the world’s mangroves, and has 31% of its land designated as protected areas. Meanwhile, the Caribbean is recognized as one of the largest centers of endemic biodiversity in the world, with approximately 50% of its plant species found nowhere else, thanks to its unique geography and climate.      

Why is Marine Biodiversity Critical to Ocean Health?

When considering biodiversity, the mind often turns first to land-based ecosystems, yet the ocean holds around 80% of the planet’s biodiversity. Healthy marine ecosystems are essential for a resilient, productive, and adaptable ocean, supporting not just ocean life but human communities worldwide.

Marine biodiversity ensures that ecosystems continue to function even as individual species’ populations fluctuate. A resilient ecosystem can withstand disturbances without collapsing, maintaining natural processes that are vital for life, such as carbon storage, water filtration, and the provision of food. Each species, from the smallest plankton to an apex predator such as the tiger shark, plays a unique role. In many cases, different species can perform overlapping ecological functions, meaning that the loss of one might not immediately disrupt an ecosystem. However, this redundancy has its limits.

What Happens If Marine Biodiversity is Lost? Many marine species have no functional equivalents. Their extinction would erase millions of years of evolution and could cause cascading effects across entire ecosystems. As biodiversity declines, so too does nature’s ability to sustain the ecosystem services we depend upon, from food security and medicine to cultural practices. 

The Mesoamerican Marine Biodiversity Hotspot

The Mesoamerican Marine Biodiversity Hotspot stretches across much of Central America, spanning subtropical and tropical ecosystems from central Mexico to the Panama Canal. Offshore and nearshore islands in both the Caribbean and Pacific Oceans add further biological richness, supporting endemic species and vital seabird nesting sites.

At the heart of this region lies the Mesoamerican Barrier Reef, extending roughly 1,000 kilometers from Mexico’s Yucatán Peninsula through Belize, Guatemala, and Honduras. It shelters over 4,000 species, including whale sharks, sea turtles, and manta rays, making it one of the world’s most significant marine ecosystems. The reef, alongside extensive mangrove forests and seagrass meadows, not only supports biodiversity but also buffers coastlines against storms and erosion.

Mangrove forests flourish along both Caribbean and Pacific coasts, particularly in Belize, Honduras, Nicaragua, Costa Rica, and Panama. Key species include red mangrove (Rhizophora mangle), white mangrove (Laguncularia racemosa), and black mangrove (Avicennia germinans), among others. These forests are vital nurseries for fish and crustaceans, wildlife habitats, and protect coastal communities from erosion and sediment loss.

Seagrass beds, dominated by species such as turtle grass (Thalassia testudinum) and manatee grass (Syringodium filiforme), also play a crucial role in maintaining healthy marine ecosystems throughout the Caribbean coasts of Central America.

A nurse shark and a Caribbean whiptail ray resting on a seagrass bed. CC Rachel Graham/MarAlliance

An interesting biogeographical divide runs through Central America: coral reefs on either side of the isthmus are built by entirely different species, with no shared reef-building corals between the Caribbean and the Pacific provinces.

Our Work in the Mesoamerican Marine Biodiversity Hotspot

At MarAlliance, we are deeply committed to protecting marine megafauna within this biodiversity hotspot and beyond. 

In Belize, home to more than 290 km of the Mesoamerican Barrier Reef and three of the four atolls in the Western Hemisphere, we have been conducting research since 2004. Lighthouse Reef Atoll has served as a key site for studying sharks, rays, sea turtles, and large finfish. Using a combination of traditional and innovative monitoring techniques, we aim to generate a comprehensive understanding of the health and dynamics of these populations.

Honduras hosts the eastern extent of the Mesoamerican Barrier Reef and extensive coastal habitats. Declared a national shark sanctuary in 2011, Honduras holds immense promise as a leader in marine conservation, though there is much work to be done to ensure the laws are simplified and enforced. Our research here is helping to establish the first baseline data for shark populations across the country, having successfully completed surveys in the Bay Islands, the Miskito Cays, and along the northwestern coast of the country. A national educational campaign debuting this year will serve as a template for our broader strategy to catalyse behavioural change for Central America’s sharks through immersive education exhibits in Honduras, Belize, and Panama. This critical information supports the evaluation and future management of the country’s marine protected areas (MPAs) and its national shark legislation.

In Panama, we are advancing marine megafauna conservation by generating vital data on species abundance and distribution. Our work informs legislation aimed at protecting sharks, rays, and large fish species. Collaborating closely with local fishers, we conduct ongoing wildlife monitoring in and around the country’s marine protected areas, promoting stewardship and sustainability. We also co-launched a major coral reef conservation and research initiative in Guna Yala, marking the most comprehensive reef and fish assessment in the region in over two decades. This effort addresses the urgent need for updated data to guide the protection of these vital ecosystems.