The hidden impacts of shipwrecks

Shipwrecks are seen as mysterious past remains. Those silent giant resting at the bottom of the oceans hold many stories of pirates, commercial trade and explorations. Those wrecks arouse our curiosity. both imposing and fragile, wrecks represent fragments of the past frozen in time, lives that were suddenly cut short due to storms or others reasons. But beyond their historical significance, shipwrecks also reveal much more than just a sudden end.

Indeed while shipwrecks hold great archaeological value, their environmental impacts are also worth discussing as they hold both a positive and a negative impact on the marine ecosystems.

On the one hand, shipwrecks, at least the most recent ones, hold massive amounts of hydrocarbons in their thanks. For now the oil is contained within the wrecks. The problem is that slowly, the boats’ metal walls are corroding which weakens the vessels, and increases the risk of an oil spill. An oil spill would be a disaster for the marine ecosystem. Plants, fishes, shellfish, crustaceans, mammalians, birds, every living species would be affected and the balance of the ecosystem would be ruined causing large impacts.

Taking the example of the most important oil spill in the USA, on the 20th of April 2010 the Deepwater Horizon platform exploded discharging 750 million litters of oil in the Golf of Mexico. The consequences of this historical oil spill have been analysed closely.

For five years after the explosion, 75% of the dolphins pregnancies failed, i.e. they miscarried or the babies were stillborn. Up to 170 000 turtles were killed. Some fish, shrimp and squid populations have fallen by 85%. Sources have also reported 800,000 dead birds. The deep seas fauna has also been impacted by this oil spill. These areas have been described as ‘toxic waste dumps’, where elements of marine life normally found there have completely disappeared.

Alongside this threat of marine oil spill, we can also mention the problem of microplastic. Vessels are equipped with many objects, furniture, tools, that all have some plastic components. Those plastics are decomposed with time creating microparticles that spread unseen in the waters. Those particles are consumed by animals and accumulate in their flesh which in turn will be consumed by humans. Microplastics are invading our food supply and becoming dangerous for humans’ health. According to a WWF report, humans ingest approximately 5 grams of plastic per week which represent the amount of a credit card plastic.

Finaly, shipwrecks attract tourists. Impressed by the magic that the wrecks hold, tourists comes in large numbers in the deep sea to admire these old vessels. The wrecks are often hosting many species of animals and corals which makes the scuba diving even more incredible. The problem is that the over frequentation of those artificial reefs by humans is affecting the ecosystem. The marine biodiversity is stressed out by the presence of humans. These latest sometimes damage the corals structure or leave their belongings or waste behind. Tourists use some equipment’s like flashlights that impact the behaviour of some species.

On the other hand, wrecks have a an enormous potential of artificial reefs. Once cleaned of harmful chemicals, plastics and hydrocarbures, shipwrecks transform into something extraordinary : thriving reefs. The metal and wood walls and structures are ideal for species to hang on or to hide from predators. Marine species gather here, creating new homes in the metal structures.

As oceans warm, species are moving towards the poles in search of cooler waters. These artificials reefs that are the shipwrecks offer a place to those species where they can rebuild and thrive.

Shipwrecks hold a dual identity both as sanctuary and a threat for the marine biodiversity. It is important to manage those shipwrecks strategically so that we take advantage of their positive impacts on the biodiversity without having to suffer their threat.