The Washington Department of Fish and Wildlife (WDFW) and additional agencies have been tracking toxic chemicals in the Pacific Northwest. Even with indications that the environmental quality is improving, ecosystems are still in danger are others. One contaminant such as polychlorinated biphenyls (PCBs) indicates the ingestion of PCB’s throughout various food webs is a new concern. A series of studies suggest the PCBs are moving from smaller to larger fish. The first thought that PCBs in the sediment was moving through benthic community and fish eggs, but current studies have opened up yet another pathway.
The beloved icon of the Pacific Northwest is the Southern resident killer whale aka orca. These large mammals have taken on the burden of carrying some of the highest levels of PCBs in the world. Researchers continue to search out the how and why this is occurring and propose a shift in thinking how some of the region’s most damaging pollutants enter Puget Sound. Currently PCBs are thought to travel via the food web from phytoplankton to the orca. The orca stores the PCBs for its existence while alive and until it has decomposed.
Polychlorinated biphenyls (PCBs) are a class of manmade organic compounds and approximately 209 individual forms. With its low flammability and chemical stability, they were used mostly in transformers to transfer heat, but also in pesticide extenders, lubricants, hydraulic fluids and adhesives. The properties of PCBs were commercially desirable and this ability to resist degradation is why they exist today in the environment as a pollutant. They bind to sediment and soil particles and being hydrophobic the bioaccumulation in aquatic organisms is where they stay.
The Puget Sound food web starts from with phytoplankton being eaten by zooplankton, herring eat zooplankton, salmon eat herring and large mammals (orca whales) eat salmon. The biomagnification occurs throughout the food web and the apex predator (orca) has the highest PCB concentrations. The multiple sources of PCBs range from industrial point sources, storm drains and moved around by weather in forms of precipitation.
Compared to other waterways, Puget Sound seems to have a considerably higher level of PCBs in its living creatures. However, the concentration at the seafloor in its sediments is comparatively low. The root causes of this phenomenon are being researched to narrow down the causes. To say that the PCBs are diminishing over time may be misleading as the research shows another aspect on the PCB contamination levels. Indicating a shift in where the PCBs are stored as they continue to resist degradation.
The beloved Southern resident killer whale’s aka orca relies on a food web and ecosystem for its sustainability. The chinook salmon is a main source of food for the orca but is full of PCB toxic contaminants. PCBs stored in the fat of the salmon is transferred to the orca fatty tissues. Recent findings about how toxic chemicals creep into the food web, causing harm to species from herring and salmon to killer whales, could strengthen commitments to control pollution pouring into Puget Sound.
Researchers with the Washington Department of Fish and Wildlife (WDFW) and other agencies have been tracking toxic chemicals — including polychlorinated biphenyls (PCBs) — as they move from smaller to larger animals in Puget Sound. The killer whales’ feedings have taken advantage of the salmon, while they have adapted to take advantage of the salmon cycle it has come with a high cost. The killer whale species eat the large, fatty Chinook salmon. These killer whales are fattening up on salmon which contain high concentrations from the ecosystem’s food web. The diet of the killer whale is so contaminated due to human persistent organic pollutants (POPs) like PCBs, PBDEs and DDTs along with lead and mercury. The Washington Department of Health has set limits on human consumption of salmon to about 8 oz per week of the chinook salmon. The waters of Salish Sea may be the cleanest, but the spread of PCBs continues within food webs.
The adult orcs consume about 300 pound of salmon a day and up to 400 pounds if pregnant. The orca eats the whole salmon and the contaminants stores in one species fatty tissue goes to the apex predator fatty tissue. Puget Sound has a large urban area, large rural human population, and many industrialized ports and shorelines. These all provide a large source of non-point and point source pollution to waterways and coastal waters. Thus, the water acting as a pathway to the organisms throughout the ecosystems receive the pollutants. Bioconcentration occurs when the contaminants may enter through the organism’s gills or tissues. The bioaccumulation is a step process which chemical contaminants increase with each step of the food web. And the biomagnification is were contaminants are concentrated at levels that exceed equilibrium from dietary absorption of a chemical. The study of the Puget sound food web is showing that the pathway is linked to the biomagnification of the food web. Starting with the breaking up of PCBs by plankton and absorption to the lowest level of the Puget Sound food web. The apex predator being that of the orca and the migration from California to Alaska transports the pollutants with in the organism’s body the whole time.
The toxicity of the PCBs may affect the immune, reproductive, nervous, and endocrine systems of humans and other species too. Ties to cancer in animals and likely to cause cancer in humans as well, thus the ban in 1970s came about with negative health and environmental impacts. Manufacturing of PCBs was banned in 1979 with the Toxic Substances Control Act
Puget Sound is surrounded by large urban and rural human population, and industrialized ports. The Sound takes in numerous sources of non-point and point source pollution to Puget Sound (Konasewich, et al. 1982). The coastal environment receives chemicals that are measured in the sediments and testing in 1982 has been found in 183 organic compounds in the sediment, biota and water. Later studies in 1988, have found that toxic chemicals are present in many benthic and pelagic organisms in Puget Sound.
Understanding the terms of Bioconcentration (intake of chemical contaminants through tissue or gills and concentration exceeds that of the environmental levels), Bioaccumulation (chemical contamination increases with each step-in food web), and Biomagnification (chemical contaminants are concentrated at levels exceeding chemical equilibrium from dietary absorption of chemical). Taking into consideration the experimental partition coefficient, PCBs have a high coefficient thus a surrogate for lipids. PCBs are highly lipophilic and very hydrophobic. (Konasewich et al.)
A 2011 report by the Washington Department of Ecology (West et al. 2011) covers Persistent Organic Pollutants (POPs) in marine krill from Puget Sound. The report shows krill exhibited correlation with urban waters, suggesting urban waters represent where POPs enter the pelagic food chain. Entering the food web PCBs suggested to start in coastal areas and settle in the basins. The devastation starts here at the bottom of the food web and continues throughout the food web. The larger species carry the toxic pollutants in the fatty tissues up and down the pacific coast and into the Strait of Juan De Fuca and Puget Sound. Even though the basins differ as high concentrations in urbanized areas and low concentrations in less developed the accumulations of PCBs in krill was similar. The flow of tidal water and exchanges needs to be researched to show any correlations with pollutants and contamination of the waters.
The 20-year report Puget Sound Assessment and Monitoring Program (PSAMP) has monitored POPs in number of species. The studies have raised questions regarding the pathways of POPs from terrestrial sources end up in the Puget sound food web and the pelagic food web exhibits high exposure to some POPs. This goes back to the killer whales as apex predators taking in the POPs from terrestrial sources. The sediment contaminations may vary and show signs of diminishing but the increase in food web levels may indicate where all the POPs have migrated to as part of the ecosystems cycle. But how much can the ecosystem handle and what is the threshold for these consequences of the human species.
Another consideration was found as to the potential for remobilization by boats and personal watercraft of the sediment contaminant concentrations (Kennish 2002). The impacts of motorized water craft on shallow ecosystems needs to be considered. The estuarine and coastal marine environments serve as a repository for chemical contaminants from human interactions with the earth. Turbulent processes whether natural or due to human activities facilitate the remobilization and dispersal of pollutants. Shallow water areas are susceptible to watercraft propellers and the pressure of waves. The contaminated sediment within coastal waters and estuaries start out as sites that take in the contaminants delivered by the watersheds and air sheds too. The landscape of Washington takes all the human activities byproducts to the waters for distribution and stored until disturbed once more.
Puget Sound is comprised of many different basins that accept the loading pathway from atmospheric deposition, surface runoff, publicly-owned treatment works (POTWs) and direct ground water. One of the latest reports as to PCBs contaminant shows Whidbey Basin providing more than half of the Puget Sound Total from surface runoff. Detailed reports covering all many contaminants has surface runoff as the leading pathway to the coastal environment. However, once the contaminants reach the water edge they are dispersed in different ways to the ecosystems. With the human interactions sending all this pollution to ecosystems to resolve the other species are faced with devastation. Therefore, it is up to all humans to work together across the globe to resolve such destructive actions.
The actions of the Washington ecological sector have demonstrated a forward movement with various models. The techniques used in the various models and approaches reflect greatly on the Fundamentals of Toxicology from our course. While reading the report it steps the reader through the process of why certain data was used to start off with. Altering approaches and producing a more accurate model allowed for the next phrase as other metals and contaminants were added to the model. The application of the model reveals the calibration used, sensitivity analysis and various scenarios. The figures then paint a dismal path of destruction on the Puget Sound but does provide guidance.