Do sunken ships help or harm marine life? What in the World podcast, BBC World Service

Key Concepts:

• Artificial reefs: Man-made structures placed on the seabed to provide habitat for marine life.
• SS United States: A large cruise ship planned to be sunk off the coast of Florida to create an artificial reef.
• Colonization: The process by which marine organisms inhabit and establish themselves on artificial reefs.
• Biodiversity: The variety of life in a particular habitat or ecosystem.
• Decontamination: The process of removing pollutants and contaminants from a structure before it is sunk.
• pH Neutral: A state where a substance is neither acidic nor alkaline, ensuring it doesn't harm the marine environment.
• Invasive species: Non-native organisms that can harm the local ecosystem.
• Seagrass meadows: Underwater flowering plants that are important for carbon sequestration and marine habitat.
• MUSA (Museo Subacuático de Arte): An underwater sculpture park in Mexico designed to attract tourists away from natural reefs.

1. Introduction: Sinking the SS United States

• The BBC World Service's "What in the World" discusses the planned sinking of the SS United States, a massive cruise ship, to create the world's largest artificial reef.
• The goal is to improve biodiversity, local tourism, and fishing.
• Georgina Rannard, climate and science reporter, provides insights into the benefits and drawbacks of artificial reefs.

2. The SS United States Project

• The SS United States is longer than the Titanic and could carry over 3,000 passengers and crew.
• The ship will be sunk off the coast of Florida, joining other artificial reefs.
• The dual purpose is to create a habitat for marine species and boost tourism.
• Tourists can visit the site via glass-bottomed boats, diving, or snorkeling.
• The project aims to divert tourism from more fragile natural reefs.

3. Preparation Process

• The preparation process is lengthy, taking about one and a half years.
• The ship contains contaminated materials like metal, plastics, oils, and chemicals, which must be removed.
• Decontamination involves cleaning and removing all hazardous materials and paint.
• Historically, sinking ships involved using explosives to flood the vessel.
• The SS United States project is estimated to cost around $10 million.

4. Colonization and Habitat Creation

• Colonization is largely a natural process.
• Within five years, artificial reefs can see an increased number of fish, coral, and algae.
• Species colonize the interior spaces of the ship, such as dining rooms and cabins.
• In some cases, coral transplantation is used to accelerate the colonization process, as seen in Mexico.
• The establishment of plants creates nutrients, attracting fish and establishing a biological cycle.

5. Environmental Risks and Regulations

• There is a risk of toxicity and pollution if decontamination is not done properly.
• The US has a regulated industry for preparing ships for artificial reefs.
• Companies specialize in taking ships that are no longer commercially viable and preparing them for sinking.
• Historians argue that the SS United States should be preserved as a museum instead.

6. Motivations and Controversies

• Creating artificial reefs is an involved and potentially inconvenient way of disposing of ships.
• The decontamination process is costly, and materials like scrap metal could be sold.
• The sinking of historic ships is controversial, with some arguing for their preservation.
• Proponents argue that it preserves the ship's legacy and provides value on the sea floor.

7. The Scale of Artificial Reefs

• There are approximately three million shipwrecks on the sea floor.
• Artificial reefs cover about 19 square kilometers (seven square miles) of the US sea floor.
• The main question is whether sinking structures is the best way to protect marine species threatened by global warming and pollution.
• Environmentalists argue for focusing on protecting existing natural environments.
• Various items, including airplanes and New York subway cars, have been sunk to create artificial reefs.

8. Best Practices and Materials

• Japan has been creating artificial reefs for 400 years to attract fish for fishing.
• The US has been doing it since the 1970s.
• Materials should be environmentally safe and pH neutral to avoid altering ocean chemistry.
• A failed project in the 1970s involved sinking three million tires, which released toxins and damaged coral.
• Proper anchoring is crucial to prevent damage to surrounding ecosystems.

9. Types of Artificial Reefs

• Most artificial reefs are custom-made structures.
• MUSA in Mexico features 500 sculptures, including human figures and a Volkswagen car, made of beneficial or neutral materials.
• Cones with holes are used to protect seagrass meadows and coral reefs.
• Some reefs are designed to protect coastlines from erosion and storm damage.

10. Evidence of Effectiveness

• Long-term impacts are difficult to study due to the complexity of separating variables.
• Short-term studies show a bloom of life, with fish colonizing and creating nutrient cycles.
• Non-native species can also colonize, potentially harming the environment.
• One study showed seagrass colonizing an artificial reef, attracting fish.
• A concrete reef in Puerto Rico saw short-term growth in fish and coral but also a seaweed bloom due to nutrient imbalance, leading to coral death.

11. Long-Term Concerns and Trade-offs

• There are concerns that artificial reefs may disrupt natural ecosystems by drawing species away from them.
• Artificial reefs can divert tourists from over-visited natural reefs.
• Artificial reefs cannot replace coral reefs; both need to be maintained.
• Protecting coral reefs from pollution and ocean warming is essential.

12. Conclusion

• Artificial reefs offer potential benefits for marine life and tourism, but their long-term impacts are still uncertain.
• Careful planning, proper materials, and thorough decontamination are crucial to avoid environmental harm.
• Protecting existing natural reefs remains a priority.