Chemistry:WDFW Toxics in Biota fish monitoring

Fish are an important component of the Washington Department of Fish and Wildlife's (WDFW) Toxics in Biota Program, part of the Puget Sound Ecosystem Monitoring Program (PSEMP, recently renamed from PSAMP). Since 1989 fish indicator species have been used to monitor contamination of Puget Sound by chemicals such as poly-chlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), pesticides, and metals. English Sole, the first species studied for the Toxics in Biota Program, have been used for monitoring by WDFW since 1989. As of 2015 the program also monitors copper rockfish, quillback rockfish, brown rockfish, coho salmon, chinook salmon, Pacific herring, and Pacific staghorn sculpin. Exposure and effects of each contaminant are monitored for each species, and more in-depth studies of specific regions are performed if monitoring indicates a contamination problem.

Geographical characteristics making Puget Sound especially susceptible to contaminants include funneling of fish through narrow inlets, restricted exchange of water, shallow sea floor sills, and freshwater inputs from urban sources. One of the largest sources of contaminants is stormwater runoff. During heavy rain events metals, persistent organic pollutants (POPs), and pesticides flow untreated into local waterways, streams, and lakes. Impervious surfaces such as roads provide a route for deposition of metals and POPs by cars and industrial emissions, before subsequent discharge into nearby water bodies. The highly urbanized coastline of southern Puget Sound results in stormwater runoff containing high concentrations of contaminants.

Three study types

Three types of Toxics in Biota studies are performed by WDFW, usually in sequential order. Baseline Assessment Studies examine temporal tends in contaminants. Focus studies are performed in regions where Baseline Studies indicate contamination. Focus Studies provide specific spatial distributions of contaminants in Puget Sound regions and their effects on biota. Pilot Studies are used to test the assumptions of the two former studies. For example, a Baseline Study indicating high concentrations of PCBs in rockfish may lead to a Focus Study determining that endocrine systems of rockfish in that region may be disrupted by PAHs at these concentrations. Pilot Studies would then examine the extent to which factors like age influence disruption of rockfish endocrine systems. Pilot Studies are only necessary if there is no literature available to address the assumptions of Baseline and Focus Studies.

Contaminants and methods of analysis

Contaminants

Contaminants monitored in fish include polycyclic aromatic hydrocarbons (PAHs), poly-chlorinated biphenyls (PCBs), certain chlorinated pesticides, mercury, and lead. PAHs are commonly produced by burning organic matter, and can be carcinogenic. PCBs are highly toxic to aquatic life, persisting for long periods of time in the environment and bioaccumulating in organisms. PCBs are the class of contaminant most often identified in high enough concentrations to cause harm to Puget Sound fish. Chlorinated pesticides like DDT are toxic to fish and persist for decades in the environment. Metals such as mercury can damage the central nervous system of fish.

Analysis methods

Methods used to measure exposure and effects from these contaminants include bioaccumulation in tissue and bile, liver lesions, endocrine disruption in male fish, and abundance of fish populations. The three types of studies performed by Fish and Wildlife examine changes in contaminant exposure over time, their spatial distribution, and the effects of exposure on each species of fish. These data are also used to issue human health advisories on the consumption of fish in Puget Sound based on Department of Health recommendations.

Several different assays are performed to quantify concentrations of these toxicants in fish tissues. Chemicals such as PAHs that are converted to metabolites within the fish are quantified by measuring concentrations of the metabolite using high-performance liquid chromatography and a quantification method. Metal concentrations in tissues are analyzed using atomic absorption methods.

Spawning success

Estrogenic substances in the environment can disrupt the sexual development of fish, inhibiting testicular growth and sperm production. Biomarkers are often used to monitor concentrations of these endocrine disruptors in the environment. Vitellogenin, a sex-specific protein, is synthesized in the liver of fish in response to estrogen, a female hormone. This protein is produced when males have high concentrations of estrogens circulating in their bodies, indicating endocrine disruption. Quantification of vitellogenin is performed by measuring competitive binding to an enzyme in the presence of another identifiable protein, usually one that fluoresces. Liver disease is examined in English Sole as an indicator of PAH contaminated sediments by removing liver samples and searching for lesions under a microscope. Spawning success is determined by analysis of reproductive organs under a microscope and is compared with bioaccumulation of contaminants for correlation.

Species monitored

WDFW monitors contaminant bioaccumulation and effects in Puget Sound fish that are abundant or ecologically valuable. Bioaccumulation of contaminants for each species is dependent on several factors. Fish that live longer, that do not migrate to other regions, and that live near sediments are more likely to be exposed to toxicants. In addition, fish at higher trophic levels and fish with high fat content accumulate more contaminants. The following species have been studied by WDFW in Puget Sound:

English sole were the first species monitored in the Toxics in Biota program. They live up to 21 years and are demersal, living close to sediments. Because their movement within Puget Sound is limited and they are in contact with contaminated sediments, bioaccumulation of toxicants is reflective of contamination in regions where they are collected. From 1989 to 1999 English Sole were monitored annually for contaminant bioaccumulation and liver lesions. Since then bi-annual monitoring has occurred throughout Puget Sound, particularly in urban regions like Tacoma and Seattle.

Rockfish, another demersal species, are often in close association with toxic sediments and consume contaminated benthic invertebrates. They have an increased risk of exposure to contaminants because they can dwell within the same contaminated basins and inlets accumulating toxicants their entire lives, particularly in the central and southern Puget Sound basins. Three species of rockfish have been monitored bi-annually since 1990. Quillback, copper, and brown rockfish are quite long-lived, with the oldest collected for the Toxics in Biota program estimated at 60, 46, and 27 years respectively.

Pacific Herring are pelagic and have a large home range as adults, but when they spawn on near-shore habitats they become exposed to lipophilic molecules like PCBs. Fertilized herring eggs in contact with sediments during their 14-day incubation period are exposed to persistent bioaccumulative toxins at a particularly vulnerable stage of life. Because their life spans are generally under 6 years, tissue bioaccumulation of contaminants is reflective of recent environmental conditions. Baseline monitoring of herring has been carried out annually since 1999.

Chinook salmon and coho salmon spend early life in freshwater and adult life in marine waters before returning to freshwater to spawn and die. This migratory life history exposes salmon to a wide variety of contaminants. Biomagnification of toxicants is often a problem in salmon due to a varied diet of benthic invertebrates and fish. The high fat content of salmon muscle tissue also increases accumulation of lipophilic contaminants. Coho and chinook have been monitored since 1990, with samples currently being taken twice each year.

Pacific staghorn sculpin are another demersal species occupying a high trophic level, feeding on other fish and benthic invertebrates like crabs and mollusks. Their eggs are laid on muddy, sandy, or rocky substrates, allowing reproductive impairment studies to be performed on site. Restricted movement and a life span of up to 10 years makes bioaccumulation of toxicants in sculpin indicative of spatial patterns of contamination. The WDFW website does not indicate that Pacific staghorn sculpin are currently monitored however.