Over a thousand unwanted subway cars are being dumped into the ocean in the United States. But worry not environmentalists; these are going to form artificial reefs. Over at amNewYork there’s a video of carriages being dumped – sorry, recycled – into the sea and Robert Martore, of the South Carolina Department of Natural Resources, tells you “it’s not a means of waste disposal”. Perish the thought. In fact, says Martore, “they’re almost custom made to be fish houses”.

I guess fish love asbestos then – Newsday and others note that there is plenty of the carcinogen in the carriages. Removing it would have cost $27 million. “New Jersey’s artificial-reef program should only utilize the highest quality materials. There are unanswered questions about the integrity of the subway cars,” Tim Dillingham of the American Littoral Society says in the Asbury Park Press.

Subway cars are made of thinner steel than ships sunk for reefs and tend to degrade reasonably quickly. A 2005 report from New Jersey states that subways cars are prohibited for use in reef construction there, but authorised a pilot study using them. Now either the evidence has changed or the finances have. The Press of Atlantic City quotes numerous studies cited in justifying the decision. It also notes that subway cars are not an acceptable material for artificial reefs under current state guidelines and under the Army Corps of Engineers permits for the sites in that area. Those are now in the process of being changed.

Some artificial reefs appear to have been successful. Others less so. Earlier this year divers began dismantling a failed artificial reef made of tyres in Florida that had come loose and started damaging coral (Nature, subscription required). Doubts have also been aired about plans to leave oil rigs in place as artificial reefs after they become redundant (Nature, subscription required).

Image: Natural coral among artificial reef materialsby Dr James McVey / NOAA