Fire Retardants Harm Killer Whales
High Levels of PBDE Contaminate Endangered Orca Off British Columbia
Feb 22, 2008
The killer whales (Orcinus orca) of British Columbia are facing multiple threats, the latest of which is exposure to PBDEs. Habitat loss, reduced numbers of their preferred prey (salmon) and ocean noise are also taking their toll on these orca populations.
The Orcas of British Columbia
These killer whales are separated into three groups-residents, transients and offshore. The resident populations in BC are further split into northern and southern resident groups. Resident populations of orca feed preferentially on salmon, while transients are known for feeding on other marine mammals. Very little is known about the offshore population, which has just recently been determined to be a separate group.
The southern resident population, known to many as J, K and L pods, was listed as endangered under the US Endangered Species Act in 2005. The three pods have been tracked for more than 30 years, providing researchers with much valuable information on killer whale behavior and life history .
PolyBrominated Diphenyl Ethers (PBDEs)
PBDEs are used as flame retardants in many common household items, including furniture, synthetic fabrics and computers. Recently it has been learned that these chemicals are released into the atmosphere even if the materials they are embedded in have not burned. Studies have linked PBDEs to health problems in domestic cats as well as humans and other wildlife.
While loss of human life and property from fires is undeniably an important issue, the negative health effects of PBDEs would seem to outweigh their potential benefits. Their persistence in the environment seems to match that of PCBs, which are also found in the orca at levels well above those proven to be toxic to harbor seals.
Both PBDEs and PCBs are endocrine disrupters. They have damaging effects on thyroid function and Vitamin A, immune function and reproductive health. And they are carried in the atmosphere far from their point of origin, where they may settle into aquatic sediment. This is where the fish that are the killer whales' primary diet become contaminated.
New Information Bad News for Killer Whales
The latest data, provided by Dr Peter Ross of Canada's Department of Fisheries and Oceans, shows that all of the populations of killer whale off of British Columbia have high levels of PBDEs to add to their other pollutant loads. The southern resident and transient populations showed higher levels of PCBs than the northern resident population.
Sadly the southern resident orca are also exposed to higher levels of ocean noise. When added to the concerns over loss of habitat, especially in the Puget Sound area where the human population continues to grow, and reduced numbers of salmon and other prey fish, the future of the southern resident population is at risk.
Efforts are underway in both British Columbia and Washington state to ban PBDEs and to improve the habitat of this important population of orca. These efforts should be mirrored throughout both countries if there is to be real reduction in PBDE levels in the environment.
 |
