Protecting the coral reefs of Culebra

Today’s Image of the Day from NASA Earth Observatory features Culebra Island, located about 17 miles east of Puerto Rico. 

The unique marine ecosystems of Culebra include extensive coral reefs safeguarded by the Culebra National Wildlife Refuge and the Luis Peña Channel Natural Reserve. 

Known as the “rainforests of the sea,” coral reefs host a diverse array of marine life. They are formed from the calcium carbonate excreted by tiny organisms called polyps.

Although coral reefs occupy less than 1% of the ocean floor, they are crucial habitats for nearly 25% of ocean species at some stage of their lives.

Landsat image of Culebra 

This Landsat 8 image – captured on February 10, 2024 – illustrates Culebra’s varied landscapes, ranging from the dry forests covering its hills to the stunning sandy beaches along its northern shore. 

“Deeper (dark blue) waters surround the island and nearby cays, while shallower (light blue) waters line the shores and lagoons. The green areas in shallow water are likely coral reefs, though seagrass meadows and seaweed patches can look similar,” noted NASA.

“You can absolutely see patch reefs east of Culebra in this image. But know that many of its reefs are located near the shore and are not easy to distinguish in Landsat imagery, depending on the depth of the water and the type of coral,” said Juan Torres-Pérez, a research scientist at NASA’s Ames Research Center.

Fringing and patch reefs 

NOAA’s detailed benthic habitat maps reveal that fringing and patch reefs are prevalent around Culebra, particularly to the north and east, with seagrass and seaweed meadows more common in the southern shallows. 

Fringing reefs are the most common type of coral reef. They are directly attached to a shore or border a landmass with little to no lagoon between the shore and the main reef body. Fringing reefs grow seaward directly from the coastline.

Patch reefs are small, isolated platforms of coral that can occur independently or within a larger system of reefs, such as a barrier reef. They often appear as “patches” dispersed throughout a lagoon, separated by areas of sand or sea grass. 

The reefs of Culebra feature key species such as branching staghorn and elkhorn corals, as well as mound-shaped and brain corals.

Environmental threats

Environmental threats such as coastal development, overfishing, and warming, acidic waters challenge reefs worldwide, including those around Culebra. 

Local issues, like increased runoff from development, also threaten these delicate ecosystems by introducing harmful pollutants. 

Furthermore, record-high global ocean temperatures in 2023 have led to a significant coral bleaching event, affecting reefs across 62 countries and territories.

The ongoing marine heat wave poses an added risk, especially with higher starting sea surface temperatures this summer compared to last. 

OCEANOS program 

NASA’s OCEANOS program is actively involved in studying and conserving these reefs. This program, designed for Hispanic/Latino high school graduates and first-generation college students in Puerto Rico, offers training in remote sensing, coral reef ecology, and other marine sciences.

In partnership with Sociedad Ambiente Marino, NASA’s efforts include planting over 160,000 coral pieces around Culebra to strengthen the reefs. 

This summer, OCEANOS students will also learn about coral farming, beach profiling, reef ecology, 3D printing of coral colonies, and seagrass conservation, further contributing to the health and resilience of Culebra’s marine environments.

Culebra Island 

Culebra Island is renowned for its stunning natural beauty and laid-back atmosphere. This small island is part of the Spanish Virgin Islands and is less commercialized than its neighbor, Vieques, or the main island of Puerto Rico. 

It’s especially famous for Flamenco Beach, often ranked among the most beautiful beaches in the world with its white sands and clear, turquoise waters.

Culebra has a protected wildlife refuge that covers approximately one-third of the island, providing shelter to a variety of wildlife, including sea turtles and seabirds. 

The surrounding coral reefs are vibrant and full of marine life, making it a popular spot for snorkeling and diving. Despite its small size, the island has a rich history, having been used as a naval gunnery and bombing practice site until 1975.

Today, Culebra is a favorite destination for those seeking a peaceful retreat in nature. The island’s emphasis on conservation and its community’s commitment to preserving its natural environment make it a unique place for eco-tourism. 

Visitors can also enjoy hiking, kayaking, and fishing alongside the local population, which is known for its warmth and hospitality.

Image Credit: NASA Earth Observatory 

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