Sri Lanka’s waters, rich in marine biodiversity, are home to an astonishing 115 shipwrecks, dating back to as early as the second century BCE. These sunken vessels, long abandoned, have evolved into vibrant underwater ecosystems, attracting a diverse range of fish and providing valuable insights for marine conservation. A recent study conducted off Colombo’s coast has revealed that shipwrecks often support richer and more varied fish communities than natural coral reefs, offering an important lesson for both marine researchers and dive tourism enthusiasts.
The Shipwrecks of Colombo
One of the most prominent shipwrecks studied is the MV Thermopylae Sierra, a massive 155-meter bulk carrier that sank in 2012. Despite its abandonment, the wreck has become a thriving habitat for marine life. In addition to the Thermopylae Sierra, the study also focused on the Medhufaru wreck (sunk in 2009) and the Nilgiri tugboat (sunk in 1997), both of which have become popular dive sites.
In comparison to nearby natural coral reefs like Barracuda Reef and Anchor Point, these shipwrecks hosted significantly higher fish densities. A staggering 2,169 fish were recorded on the wrecks versus 749 on the coral reefs, highlighting the more complex structure of wrecks and the diversity of microhabitats they create. These structures, with their various crevices and overhangs, offer shelter, food, and safety for fish, making them crucial to both marine biodiversity and the livelihoods of local fishers.
Fish Communities and Their Preferences
The study, led by marine scientist Nishan Perera, identified a variety of fish species thriving around the wrecks. Snappers, commercially important for local artisanal fisheries, were especially abundant, while other species, like cardinalfishes and fusiliers, preferred the wrecks over the reefs. Interestingly, coral reefs were more popular with species like damselfishes and barracudas. This difference in fish assemblages underscores the unique ecological roles that both shipwrecks and natural reefs play in supporting marine life.
A method called diver-operated video transects allowed researchers to quantify and identify fish species with precision. The technique involved divers using cameras to capture footage along predefined paths on the wrecks or reefs, providing valuable data for post-survey analysis.
The Potential for Artificial Reefs
Sri Lanka’s government has also experimented with creating artificial reefs by sinking discarded buses and train compartments into the sea. While these structures show promise in supporting fish populations and deterring harmful activities like bottom trawling, experts like Arjan Rajasuriya from the National Aquatic Resources Research and Development Agency caution that such artificial reefs may not stand up to the harsh underwater environment in the long term.
However, the study on shipwrecks offers important lessons on how to design and develop sustainable artificial reefs. By mimicking the complex structures of sunken ships, artificial reefs could provide long-term benefits for marine ecosystems and the communities that rely on them.
Shipwrecks as Dive Tourism Attractions
Beyond their ecological value, shipwrecks hold great potential for Sri Lanka’s growing dive tourism sector. Currently, Sri Lanka generates $3 million to $5 million annually from dive tourism, but shipwreck expert Dharshana Jayawardena believes that number could increase significantly. Sri Lanka’s shipwrecks, many of which are nearly a century old, offer not only a thrilling dive experience but also immense archaeological value. The island nation’s shipwrecks surpass even those in popular dive destinations like Malaysia, Thailand, and Indonesia.
Notable wrecks, such as the HMS Hermes—the world’s first purpose-built aircraft carrier sunk during WWII—and the Roman shipwreck at Godawaya, offer a unique glimpse into history while supporting marine life. Despite the challenges posed by blast fishing and illegal salvaging, these wrecks remain an invaluable asset for both marine conservation and tourism.
