BP oil spill: Environmental impact

While almost no environmental damage results have been reported as yet – due to “litigation sensitivity” – the impact of this spill will be extremely serious.

The environmental damage is occurring in four ecosystems – the offshore waters, inshore coastal waters, the seabed, and shoreline wetlands and beaches.

Inshore
In inshore waters, the oil is distributed throughout the water column, and certainly into the inshore seabed sediments.

This will have affected much of the coastal shrimp and menhaden populations, which form the basis of the two largest fisheries in the region.

As well, the images of oiled seabirds, particularly pelicans, have become the face of this disaster to the world. The birds are nesting on coastal islands at present, and many of these islands have been heavily oiled.

The State of Louisiana lists some 600 species at risk from this spill – 445 species of fish, 45 mammals, 32 reptiles and amphibians, and 134 bird species.

And here is the body count for the large animals as of Day 60 (June 18):

Birds – total collected 1550, of which 885 dead
Sea turtles – total collected 469, dead 363
Marine mammals (mostly bottlenose dolphins) total collected 47, dead 44

And this is only the count of the ones that have been collected.

As we’ve learned from most spills, particularly offshore spills, most of the dead animals simply sink and are never recovered or counted.

One can assume for an offshore spill such as this that perhaps only 10 per cent of the large animal carcasses will be recovered, and thus multiply the observed mortality by a factor of 10.

Further, the damage in the water column will only be detected by methodical research, which has been slow to deploy. Nonetheless, it has certainly been enormous.

Shoreline
The damage to inshore wetlands and marshes will, as predicted by a federal government study in 2000, cause “severe adverse impacts” – some of them permanent. There will be a permanent loss of island habitat due to vegetation dying as a result of being oiled, and thus the accelerated erosion of the islands.

Offshore
In the offshore waters, it is virtually certain that substantial portions of the 2010 year-class of many pelagic fish species has been killed or otherwise injured by the spill.

Many species – blue fin tuna, sailfish, marlin, etc – were spawning pelagic eggs at the time in the same area and time as the spill, and many of those have undoubtedly been killed.

Additionally, many of the adult fish have been dosed with oil, and while some will have died already, many others will suffer sub-lethal injury that will persist for years. Other impacts offshore include the many sperm whales that have been seen surfacing in the oil.
One young sperm whale was recovered dead last week, and is being sampled at present.

Professor Rick Steiner, marine conservation biologist, Anchorage Alaska. Professor Steiner has been advising in the Gulf much of the past two months.