10 Animals Who Are Still Hurting From The BP Oil Spill

Brown pelicans were already a threatened species when the BP oil spill occurred. After the spill, nearly one thousand were collected for cleaning, but more than 500 died. The population has largely rebounded, with the number of brown pelicans reported nesting in 2012 nearly as high as it was pre-spill. But images of the oil-slicked pelicans became an ubiquitous part of the media's coverage, and the oil has stuck: Two years later, researchers detected chemical and petroleum pollutants from the BP spill in the eggs of white pelicans in Minnesota, chemicals that could negatively affect embryo development.

A late 2013 study found dolphins in the vicinity of the BP oil spill showed previously unseen signs of sickness, including lung damage, low levels of adrenal hormones and unhealthy weight loss.

"I've never seen such a high prevalence of very sick animals -- and with unusual conditions such as the adrenal hormone abnormalities," one of the study's authors, Dr. Lori Schwacke, stated at the time.

Researchers also found an "unusual" spike in dolphin strandings; according to National Oceanic and Atmospheric Administration (NOAA) findings: In 2013, bottlenose dolphins were found dead or stranded at rates three times higher than the average pre-spill rate.

NOAA research released in August 2013 found large numbers of sea turtle strandings in the years since the spill, with about 500 stranded sea turtles in the area affected every year from 2011 to 2013. (Historically, estimates for strandings in the area would have been closer to 100 per year.)

It's difficult to measure just how many sperm whales were affected, but one arresting photo of a rotting, burnt sperm whale carcass circulated widely after researchers saw the animal from a ship about 77 miles from the Deepwater Horizon site in June 2010. A 2013 study of sperm whale skin samples found higher than usual levels of genotoxic metals in Gulf of Mexico whales after the spill, with the whales closest to the site of the spill with the highest levels.

The genotoxic metals, including nickel and chromium, are capable of damaging DNA, causing lasting genetic impacts on generations of whales. In the short term, even a few whale deaths can affect an entire population as sperm whales, already an endangered species, give birth to very few calves.

"As soon as we get to the level of three deaths caused by human interaction -- and this would include the oil spill -- that would jeopardize that particular sperm whale population," Celine Godard-Codding, an environmental toxicologist at Texas Tech University, told National Geographic.

As water birds, loons are vulnerable to water pollution -- and researchers have found they were indeed affected by the spill. A 2013 study of loons turned up dangerous levels of PAH (polycyclic aromatic hydrocarbons) in their bloodstreams, which could contribute to anemia, weight loss, liver damage, cancer, immunosuppression and other health issues.

In the immediate aftermath, red snapper in the affected area were found with lesions and rotting fins. While such physical scarring are less common in fish four years later, a recently published study conducted between 2011 and 2013 found the population of young snappers in the Gulf unusually small, with a noticeable decline in other reef fish as well.

The Gulf Coast is home to about two-thirds of American oysters, but that population was significantly impacted by the spill. As non-moving organisms, oysters couldn't avoid the spill, and population growth was significantly down in 2011, 2012 and 2013. Across the northern Gulf of Mexico, oyster larvae were much rarer than usual, and mortality was high. According to fisherman, oyster populations are still drastically low (and fisherman can file claims for compensation as a result).

Crab populations are also down, with a major drop of blue crabs identified in 2013. One reason could be still-slick marshes, which the crabs could be avoiding as they select their habitats. The remaining crabs were still showing signs of damage as of 2013.

"People are bringing in (crabs) that are really messed up," Darryl Felder, a University of Louisiana biology professor, told the Tampa Bay Times. "The crab catches are really down, and what they're getting have big lesions on them -- lesions and fungal or bacterial infections."

These massive fish feed at the water's surface for hours. A study published in August 2013 identified uncharacteristic whale shark sightings off the Florida Gulf of Mexico possibly connected to the spill, meaning the oil altered the fish's typical migratory paths. But not every whale shark was able to avoid the oil, confirmed biologist Eric Hoffmayer to National Geographic, and the oil could clog or suffocate their gills and contaminate their prey. A year after the disaster, researchers identified the already vulnerable whale sharks as a species uniquely at risk.

The 2010 spill occurred during spawning season for yellowfin and bluefin tuna, meaning the fish embryos, larvae and newborn fish were also affected. According to a recent study, this resulted in defects in heart development, which affects the development of other organs and could lead to shortened lifespans. In addition, according to the NWF report, blackfin tuna, blue marlin, mahi-mahi and sailfish all had fewer larvae in 2010 than in the three years before.