11
Mar
Ecosystem Health: Pesticide Use from Forest Management Practices Threatens Essential West Coast Marine Organisms
(Beyond Pesticides, March 11, 2021) A Portland State University (PSU) study finds that pesticides from the forestry industry threaten clams, mussels, oysters (bivalves) along the Oregon state coast. Bivalves are excellent indicator species, signaling environmental contamination through their sedimentary, filter-feeding diet. However, continuous pesticide inputs—from various forestry management regimes—into watersheds along Oregon’s coastal zone endanger these species in downstream rivers and estuaries (river mouths).
Although research demonstrates many forestry practices (e.g.., road building, planting, clearcutting, thinning) have cumulative effects on the ecosystem, there is a lack of studies addressing the overall impact of multiple chemical mixtures and application on watersheds and subsequent aquatic transport. Like agriculture, conventional forest management across the U.S. depends on the use of toxic pesticides to control pest populations. However, pesticide residues from application drift, runoff, and contamination continuously jeopardize the health and fitness of various non-target species, including humans.
Marine ecosystem pollution is difficult to track and measure, and forestry pesticide regulations can invoke variations in water quality requirements through discrepancies in buffer zones and application concentrations. Therefore, studies like this can help guide future forest management practices to reduce the number of chemicals entering aquatic ecosystems. Researchers in the study note, “These findings highlight the need to address management practice effectiveness in controlling transport of potentially harmful compounds throughout the Oregon Coast Range. As scientific understanding of ecotoxicology evolves and new monitoring techniques become available, efforts to understand cross-ecosystem stressors are critical, especially to incorporate ecosystem-based management into watershed-scale or regional land management objectives that go beyond managing for single land use and individual classes of chemicals.”
The study identifies cross-ecosystem chemical threats to aquatic environments, particularly coastal ecosystems downstream from land-based forestry management practices. Researchers collected three species of bivalves from eight watersheds along the Oregon Coast—the Western pearlshell mussel (Margaritifera falcata), softshell clam (Mya arenaria), and Pacific oyster (Crassostrea gigas). Using a passive water sampler, researchers collected water samples from 15 different watersheds along the Oregon coast for 45 days. Scientists evaluated pesticide concentration and type in both bivalve tissue and water samples. To assess the relationship between forestry practices and downstream contamination, researchers compared pesticides present in samples to data on state-regulated pesticide use on forestland.
The study results detect 12 different chemical compounds (two herbicides, three fungicides, and seven insecticides) in both water and bivalve samples—five of which are current-use pesticides in forest management. Although pesticide concentration and type vary by season, organism, and watershed location, 38 percent of bivalve samples harbor pesticide concentrations high enough to accumulate in tissues. Indaziflam (a current-use herbicide in Oregon forestry) is present in seven percent of bivalve samples. Furthermore, water samples find current-use herbicides hexazinone and atrazine, and banned pesticides like DDT/DDE contribute to aquatic contamination downstream. The study uncovers that most contamination occurs along the Central Oregon Coast in the Siuslaw and Smith watersheds.
Pesticide contamination in waterways is historically commonplace as residues are widespread in U.S. rivers and streams. A 1998 U.S. Geological Survey (USGS) analysis revealed at least one pesticide is present in all U.S. waterways and a recent USGS report detects at least five or more different pesticides in 90 percent of water samples. Moreover, research finds millions of people already consume drinking water contaminated with pesticides or pesticide compounds from groundwater sheds. Thousands of tons of pesticides enter rivers and streams around the U.S. from agricultural and nonagricultural sources that contaminate essential aquatic ecosystems, such as watersheds consisting of surface water (i.e., lakes, streams, reservoirs, and wetlands) and groundwater. As the number of pesticides in waterways increases, it has detrimental impacts on aquatic ecosystem health, and some pesticides work synergistically with others to increase the severity of the effect. In addition to adverse health effects on marine organisms, these chemicals harm terrestrial organisms relying on surface or groundwater. Many of these chemicals cause endocrine disruption, reproductive defects, neurotoxicity, and cancer in humans and animals, and most are highly toxic to aquatic species.
Forestry management practices have long been a controversial issue for the timber industry, as environmental groups cite its contribution to non-point source pollution of surface and groundwater. Furthermore, studies find evidence of chemical contamination in nearby harvestable plants that are primarily used for medicinal uses by indigenous communities. Glyphosate use in forest management drifts to nearby wild, edible plants, contaminating them for more than a year after initial application. These plants contain glyphosate residues that exceed levels set by the U.S. Environmental Protection Agency for some food products. Providentially, there is a growing consensus between the forestry industry and environmental groups. In 2020, Oregon Governor Kate Brown (D) announced the Private Forest Accord—a collaborative effort between 13 timber/forestry operations and 13 environmental organizations to establish proactive legislation and recommendations for forest management practices. Moreover, Senate Bill 1602 was passed in the Senate and House in June 2020 and signed into law in July, changing some of Oregon’s non-federal forestland protections, such as buffer zones near streams during helicopter pesticide spraying.
The study demonstrates that pesticide use in forest management does infiltrate the watershed and transport chemicals downstream to rivers and estuaries. Likewise, the study finds past pesticide applications on orchards, Christmas tree farms, and homes further contribute to aquatic ecosystem contamination downstream. Indaziflam, the most common chemical present in bivalve tissue samples, is a potential leacher. The chemical’s leaching properties can account for its bioavailability in riverine and estuarian bivalves. The presence of atrazine in water samples is not surprising as past studies demonstrate it is pervasive in all aquatic environments, being regularly detectable in groundwater, and prone to leaching. Both indaziflam and atrazine are highly toxic in freshwater/marine organisms and fish. They can cause various health issues that have implications for human well-being, including endocrine disruption, neurotoxicity, cancer, kidney/liver damage, birth/developmental abnormalities, and reproductive dysfunction. Lastly, EPA classifies hexazinone as a carcinogen and dermal (skin) sensitizer/irritant with possible effects on birth/reproductive health and kidney/liver function. Although this chemical is slightly toxic to aquatic organisms, it is remarkably hazardous to micro-and macroalgae responsible for sustaining aquatic food webs.
Although this study finds that chemical concentrations present in Oregon’s watershed and bivalve tissue samples remain under federally established guidelines, aquatic environments continuously encounter environmental pollutants and toxic compounds known to have harmful biological consequences on both aquatic and terrestrial organisms. A recent report, “Human Health and Ocean Pollution,” finds that the combination of non-point source chemical contamination from microplastics and pesticide runoff can have an adverse synergistic effect on species’ health and ecosystem. Additionally, coastal and offshore aquaculture (farming of aquatic organisms) presents a new, looming threat to marine health. Namely, the use of antibiotics and pesticides on local marine ecosystems (e.g., insecticides to control sea lice in farmed salmon) results in coastal habitat loss and genetic and health risks to wild marine populations.
All aquatic environments are essential to human health and well-being, feeding billions, supporting millions of jobs, and supplying medicinal materials. However, marine species biodiversity is rapidly declining due to overfishing, global warming, pathogens, and pollution. This biodiversity loss may result in changes in marine and terrestrial ecosystem function and reduce ecosystem services. Therefore, this study highlights the need to identify non-point pollution sources readily contaminating aquatic ecosystems to establish regulations that mitigate adverse effects.
Study co-author Elise Granek, Ph.D., professor of Environmental Science and Management at PSU, concludes, “The levels of the particular compounds we detected are not something that federal guidelines consider harmful to human health, however, they may be harmful to animals in aquatic and marine environments. Additionally, we were just looking at a handful of compounds, yet aquatic organisms and their consumers are likely exposed to many more contaminants including microplastics and heavy metals, among others. How the exposure we detected—paired with other contaminants they may encounter in their waters—affect the animals sampled or their predators is a really interesting question and unfortunately we don’t have regulatory guidelines that consider exposure to multiple stressors.”
Chemical contamination is ubiquitous in terrestrial and marine environments. Therefore, indicator species like bivalves can act as sentinel species for chemical contamination, detecting risk to humans by exhibiting signs of environmental threat sooner than humans in the same environment. Unless more is done to address chemical pollution, humans will also continue to see similar declines in general health, fitness, and well-being.
Beyond Pesticides has long advocated for healthier and more environmentally friendly forestry practices to protect the environment and wildlife, particularly water resources. Unfortunately, within the Pacific Northwest, an area where the timber industry dominates, Oregon’s pesticide regulations do not provide adequate protection. Therefore, pesticide use should be phased out and ultimately eliminated to protect the nation’s and world’s waterways and reduce the number of pesticides that make their way into drinking water. Additionally, Beyond Pesticides has long advocated for protective, federal regulation that considers potential synergistic and additive threats, to ecosystems and organisms, from admixtures of pesticides.
Replacing pesticides with organic regenerative systems conserve water, nurture soil fertility, reduce surface runoff and erosion, reduce the need for nutrient input (i.e., fertilizers), and most critically, eliminate the use of toxic chemicals that threaten so many aspects of human and ecosystem life, including water resources. Learn more about the hazards pesticides pose to wildlife and what you can do through Beyond Pesticides’ wildlife program page.
For more information about pesticide contamination in water, see the Threatened Waters program page and Beyond Pesticides’ article Pesticides in My Drinking Water? Individual Precautionary Measures and Community Action, where Beyond Pesticides states: “This problem requires individual precautionary measures and preventive, community-based action to protect [individual and public health] and ultimately, stop ongoing pesticide use that ends up in drinking water from numerous agricultural, public land, and home and garden use. Beyond Pesticides urges a solution that keeps pesticides out of the water, rather than trying to clean them up after they enter our waterways and drinking water supply.”
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
