The damage done to the environment by the Deepwater Horizon oil spill seems to be subsiding after five years of marine devastation. Scientists report fewer dead dolphins washed ashore this year than in previous years following the oil spill in the Gulf of Mexico.
An oil rig explosion in April of 2010 killed 11 crew members and sank the rig. It took months for the oil flow to be stopped, causing a slick in the Gulf of Mexico big enough to be seen from space. Oil found its way from the spill across the gulf, damaging much marine life. Various species, from tiny creature on the seafloor to dolphins and whales were affected.
According to the Tampa Bay Times, the largest animals suffered the most. Dolphins and whales were exposed to the oil by inhalation at the surface, absorbing the oil that they came into contact with in the water, and from ingestion of contaminated food.
The National Oceanic and Atmospheric Administration, or NOAA, has been studying the effects of this spill on marine life since it happened. Earlier this year, Dr. Teri Rowles spoke about the unusual mortality event caused by the spill.
These studies have increasingly pointed to the presence of petroleum hydrocarbons as being the most significant cause of the illnesses and deaths plaguing the Gulf’s dolphin population. This study carries those findings significantly forward.
Some of the causes of death due to the oil include damage to adrenal glands, increased risk of pneumonia and a higher rate of complications with pregnancy.
As of October 11, there were 1,433 reported deaths of whales and dolphins due to oil exposure. Most of these deaths, 1,246, were of bottlenose dolphins. That is an average of 248 dead bottlenose dolphins per year since the spill as opposed to the average 74 prior to the accident.
However, the number of deaths this year dropped from the last four years according to research biologist with the National Marine Fisheries Service, Jenny Litz.
The number of mortalities in the region has declined since the peak years of 2010 to 2014.
Right now scientists are considering whether to declare the mortality event over. Regardless of the decision, there will still be years of research to be done looking at the long term effects of oil exposure on marine life.