D'Arros and St. Joseph

D'Arros and St. Joseph Special Reserve protects a remote island and atoll system in the Amirantes Group of the Seychelles outer islands, approximately 255 kilometers southwest of Mahé. D'Arros Island is a low-lying sand cay roughly five kilometers in circumference with a maximum elevation of three meters, while St. Joseph Atoll comprises 16 small islets surrounding a shallow lagoon connected by a one-kilometer-wide deep channel. Formally designated as a Special Reserve in 2020 after decades of private conservation stewardship, the reserve is owned and managed by the Save Our Seas Foundation. The SOSF D'Arros Research Centre, established in 2004, has conducted over 15 years of pioneering marine and terrestrial research, making these islands among the most intensively studied in the Seychelles outer islands. The reserve protects critical habitat for endangered green and hawksbill turtles and exceptionally rich coral reef ecosystems.

D'Arros and St. Joseph support remarkable wildlife diversity for their small size and low elevation. The islands host one of the longest-running turtle monitoring programs in the Amirantes, documenting nesting populations of both endangered green turtles and critically endangered hawksbill turtles, making it the only location in the Seychelles where both species nest and forage in significant numbers. A 2017 rapid biodiversity assessment recorded over 514 fish species in just 19 days, demonstrating extraordinary marine diversity. The reef systems support healthy populations of reef sharks, eagle rays, and manta rays. Lemon sharks use the St. Joseph lagoon as a nursery ground, with juveniles sheltering in the shallow waters. Seabird colonies include important breeding populations of sooty terns, crested terns, and lesser noddies. The terrestrial fauna includes coconut crabs, geckos, and various invertebrates adapted to the sandy island environment.

The terrestrial vegetation of D'Arros Island includes a mix of native coastal species and legacy plantation vegetation, including coconut palms and casuarina trees. Native coastal plants such as Scaevola, Tournefortia, and Pemphis form the natural vegetation fringe. Restoration efforts led by the Save Our Seas Foundation have focused on removing invasive species and replanting native vegetation to improve habitat quality for nesting seabirds and turtles. The St. Joseph Atoll islets support sparse but ecologically important vegetation including native beach crest plants that stabilize the sandy substrate. The marine environment features healthy coral reef communities surrounding both D'Arros and St. Joseph, with coral gardens in the shallow lagoon of St. Joseph supporting a high diversity of hard and soft coral species. Seagrass beds in the lagoon provide critical grazing habitat for green turtles. The lagoon's mangrove-fringed shores on some islets contribute to the ecological connectivity between terrestrial and marine environments.

D'Arros and the St. Joseph Atoll are coralline sand cays sitting on the Amirantes Bank, a shallow submarine limestone platform. At approximately 15,000 years old, these islands are geologically young, formed from accumulated coral sand and reef debris on the bank surface. D'Arros Island is a roughly oval sand cay with sandy beaches wrapping around its entire five-kilometer perimeter and a maximum elevation of only three meters above sea level. St. Joseph Atoll is a classic atoll formation with 16 islets arranged around a central lagoon, connected to the open ocean through passes between the islets. The deep channel separating D'Arros from St. Joseph, roughly one kilometer wide and 60 to 70 meters deep, creates a dramatic bathymetric transition that influences marine species distribution and current patterns. The surrounding Amirantes Bank drops off steeply on its outer edges to deep ocean floor, creating conditions for nutrient upwelling. The coralline geology makes both islands highly vulnerable to sea level rise.

D'Arros and St. Joseph experience a tropical oceanic climate moderated by the surrounding Indian Ocean. The northwest monsoon from November to April brings calmer seas, warmer air temperatures reaching 31 degrees Celsius, and most of the annual rainfall. The southeast monsoon from May to October produces cooler conditions with stronger winds that can generate significant wave action on the exposed banks. Sea surface temperatures range from approximately 26 to 30 degrees Celsius seasonally. The extremely low elevation of both D'Arros and the St. Joseph islets makes them vulnerable to storm surges and spring tide overwash. Rainfall is moderate for a tropical location, with the surrounding ocean providing the primary moisture source. Climate change poses an existential threat to these low-lying formations, as even modest sea level rise would progressively reduce the land area available for nesting turtles and seabirds.

D'Arros Island is named after Baron d'Arros, a French naval officer and administrator of the Île de France (now Mauritius) in the eighteenth century. The island was developed as a coconut plantation during the colonial period, with workers living on the island to produce copra. This plantation history is typical of many Amirantes islands. The island changed hands several times during the twentieth century, passing through various private owners. In 2012, the Save Our Seas Foundation acquired D'Arros Island and began transforming it from a private estate into a dedicated conservation and research station. The surrounding St. Joseph Atoll remained largely uninhabited throughout its history, with only occasional use by fishermen. The transformation from private ownership to conservation reserve represents one of the most significant private conservation investments in the Seychelles outer islands.

The formal designation of D'Arros and St. Joseph as a Special Reserve was announced on March 26, 2020, though the waters had functioned as an informal sanctuary for decades under the Save Our Seas Foundation's stewardship. The SOSF D'Arros Research Centre was established in 2004, initiating systematic scientific research on the islands and surrounding marine environment. For over 15 years, the research center has conducted the longest-running nesting turtle monitoring program in the Amirantes and the most detailed coral reef monitoring program in the Seychelles, using advanced techniques including stereo-video photogrammetry, baited remote underwater video systems, and visual census methods. The Special Reserve legislation bans fishing within one kilometer of the islands and prohibits any development on St. Joseph Atoll. A portion of D'Arros Island has been set aside for consideration as a Ramsar Wetland Site. The reserve represents a successful model of private philanthropic investment in marine conservation.

D'Arros and St. Joseph are not open to general tourism, with access restricted to researchers, foundation staff, and specially invited guests. The primary attractions for those who do visit are the extraordinary marine environments surrounding both islands. The coral reefs offer world-class diving and snorkeling, with the 2017 rapid assessment recording over 514 fish species highlighting the exceptional diversity. The St. Joseph lagoon provides a unique environment for observing juvenile lemon sharks, sea turtles, and rays in shallow, crystal-clear water. The deep channel between D'Arros and St. Joseph is a dramatic diving location where the shallow bank drops abruptly into deep ocean, with encounters with larger pelagic species including manta rays and reef sharks. On land, the turtle nesting beaches are the primary focus, with the research team monitoring nesting activity year-round. The seabird colonies on the St. Joseph islets are accessible only to researchers conducting population surveys.

D'Arros and St. Joseph are not open to public visitors. The islands are accessible only to Save Our Seas Foundation researchers, staff, and approved collaborators. The SOSF D'Arros Research Centre on D'Arros Island has accommodation and laboratory facilities for researchers, along with the infrastructure needed to support field operations including boats and diving equipment. There is no commercial transport to the islands; access requires a charter flight to the nearest airstrip or a multi-day boat journey from Mahé. The research center is self-sufficient in basic necessities. Scientists interested in conducting research at D'Arros must apply through the Save Our Seas Foundation. The foundation periodically shares research findings and conservation updates through its publications and website, providing a virtual window into these remote islands for the broader public.

The conservation program at D'Arros and St. Joseph combines rigorous scientific research with practical habitat management. The turtle monitoring program tracks nesting success of both green and hawksbill turtles, providing critical long-term data on population trends for these endangered species. Coral reef monitoring employs state-of-the-art techniques to track reef health, resilience, and recovery following bleaching events. Invasive species management on D'Arros Island includes removal of non-native plants and efforts to eradicate rats, which threaten nesting seabirds and turtles. The 2020 Special Reserve designation provided legal backing for conservation measures that had been voluntarily implemented for years. The no-fishing zone within one kilometer of the islands protects critical reef fish populations and the juvenile shark nursery in St. Joseph lagoon. Climate change remains the most significant long-term threat, with sea level rise endangering the low-lying islands and warming seas threatening coral reef health. The research data collected at D'Arros contributes to regional and global understanding of tropical marine ecosystem responses to environmental change.