Five years following the Deepwater Horizon oil spill, National Wildlife Federation (NWF) scientists have compiled a report detailing how 20 types of fish and wildlife were impacted by the pollution that continued for 87 days.
NWF said, “The full extent of the spill’s impact may take years or even decades to unfold , but Five Years & Counting: Gulf Wildlife in the Aftermath of the Deepwater Horizon Disaster examines what the science tells us so far.”
The report does not suggest that fishing is not good or that it will not continue to be so.
Following are updates on two species:
The mahi-mahi, also known as dorado, is an economically important species in the northern Gulf.
Like many fish, mahi-mahi produce fertilized eggs that float in the upper layers of the water column. Mahi-mahi were spawning at the time of the oil spill and it is therefore likely that their eggs and larvae were exposed to oil during 2010.
Larval or juvenile exposure to a chemical in oil from the Deepwater Horizon has been shown to cause significant developmental impacts in a number of fish species. Similar research in mahi-mahi corroborates these findings. Embryonic or juvenile mahi-mahi briefly exposed to Deepwater Horizon oil were later unable to swim as fast as unexposed fish. The concentrations of oil in the study were designed to mimic conditions in affected areas of the Gulf.
This could translate into increased mortality, as slower fish would likely be less able to catch prey or avoid predators.
These studies could help explain “crude oil toxicity syndrome,” which has been observed in a number of fish species, across both fresh and saltwater habitats.
Additional research has recently been funded that will look further into impacts in redfish and mahi-mahi.
American white pelicans nest in colonies of several hundred pairs on islands in remote inland lakes in North America, and they winter on the Pacific and Gulf Coasts.
Most white pelicans were in their northern breeding grounds at the time of the spill.
Two years after the spill, however, researchers found evidence of oil and dispersant in the eggs of white pelicans nesting in Minnesota. Scientists made this discovery at Marsh Lake, which is home to the largest colony of white pelicans in North America.
Petroleum compounds were present in 90 percent of the first batch of eggs tested. Nearly 80 percent contained the chemical dispersant used during the Gulf oil spill. White pelicans could have been contaminated while wintering in the Gulf, either through direct contact with remaining oil and dispersant or by eating contaminated fish.
Long-term increases in breeding pairs in Minnesota have occurred since 2004, but from 2011-2012 the breeding population has essentially stabilized.
Scientists from the Minnesota Department of Natural Resources are continuing to investigate the impacts of these compounds, which have been known to cause cancer and birth defects and to disrupt embryo development in other species.
Contaminated eggs have been found in two other states as well. In 2012, staff at the Upper Mississippi National Wildlife Refuge collected eggs that failed to hatch from pelican colonies in the Iowa and Illinois portions of the refuge.
Population declines in migratory shorebirds and reduced breeding productivity may have an impact on ecosystems outside the Gulf region. Therefore it is important to link wintering and breeding locations for migrant species in order to fully understand the impacts of the Gulf oil disaster.