Pollution, One of the Five Drivers of Biodiversity Loss

This week, I’m attending the Conference of the Parties to the Convention on Biological Diversity in Montreal. It has me thinking about how we got to this point, where this global meeting brings together countries and organizations from all around the world to discuss the biodiversity crisis. We got here thanks to five drivers of extinction, with pollution being one of the more insidious causes.

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Over the past 50 years, the natural world has experienced unprecedented rates of change with devastating implications. Today, approximately one million species are at risk of extinction globally, and integrally linked ecosystem services—from disease buffering to pollination—are at risk of loss. The five greatest drivers of biodiversity loss with the largest global impact are: changes in land and sea use; direct exploitation of organisms; climate change; pollution; and invasive species. These drivers are largely a result of underlying societal values and behaviors. If left unaddressed, they are predicted to continue or increase their detrimental impact. Transformative action is needed to alleviate these threats and the species declines that they contribute to.

Toxic Chemicals, Noise and the Plight of Southern Resident Orcas

Pollution is an important driver of change throughout all ecosystems, with particularly devastating effects on freshwater and marine habitats. Many types of pollution—air, water and soil among others—are increasing, with negative impacts for nature. Greenhouse gas emissions, agricultural fertilizers, plastic waste, oil spills and many other sources of pollution have had strong negative effects on the soil, freshwater, oceans and atmosphere that wildlife and people depend on. Contaminants, excess light and noise directly or indirectly threaten many species as well as human health and welfare. At the time of listing as “threatened” or “endangered” under the U.S. Endangered Species Act, more than 430 species were significantly impacted by pollution.

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Greg Goebel

Killer whales, or orcas, are an iconic species of the Pacific Northwest. Not only are orcas top predators and keystone species for local ecosystems, they are also culturally and economically important. The orca-watching industry supports over $216 million worth of economic activity in the Salish Sea region every year, generating more than $12 million in state and local tax revenue annually and supporting over 1,800 jobs. The Lhaq’temish, or Lummi Nation, are one of the many coastal Native American Tribes that have a long historic and/or spiritual connection with orcas. The Lummi people refer to the whales as “qwe ‘lhol mechen,” or “people that live under the water.” They have a special place in the traditions and culture of the region.

The Southern Resident orca population, found in the waters of Northern Washington State and southern British Columbia, was first listed as “endangered” in 2005 under the U.S. Endangered Species Act and is listed as “depleted” under the Marine Mammal Protection Act. Despite receiving federal protection, the population is still low—just 73 individuals (as of September 2022). There are many factors that have prevented these whales from recovering and one of the major issues is pollution—both from chemical pollutants and noise pollution.

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NOAA/SWFSC, SR3 and the Coastal Ocean Research Institute

Globally, killer whale populations found in the most polluted seas—around Japan, Brazil, the UK and in the Pacific Northwest—are trending toward collapse. Being a predator in this marine ecosystem, orcas sit at the top of the food web. Unfortunately, this also means that orcas are vulnerable to toxic industrial chemicals that can accumulate in their blubber. From plankton to the carnivorous chinook salmon that are essential prey for orcas, the amount of pollutants in the tissues of prey species along the entire food chain increases and magnifies in predators in a process called bioaccumulation. The highest levels are found in the tissues of the apex predator: here, that means orcas.

The most toxic type of pollutants found in orcas are Persistent Organic Pollutants, or POPs. Some of the worst POPs include Polychlorinated Biphenyls (PCBs – used in electrical equipment and military equipment such as submarines), Polybrominated Diphenyl Ethers (PBDEs – commonly used as flame retardants), Dichlorodiphenyltrichloroethane (DDT – an insecticide historically used in forestry and agriculture), and dioxins and furans (byproducts of burning plastics, wood and fossil fuels). These pollutants accumulate in the fatty blubber layer of the whales. When the food supply becomes low, such as during periods of low chinook salmon availability, the whales start using up this fat layer, releasing these toxic POPs as well. High levels of toxic heavy metals such as mercury and cadmium have also been found in orcas.

Even if the levels of these pollutants are not high enough to kill orcas directly, many are damaging to their health in smaller concentrations; for example, they cause immune system damage and make animals more vulnerable to diseases. In addition, these chemicals can affect the reproductive system, increasing the likelihood of unsuccessful pregnancies or reducing the likelihood of conception. Because some of these pollutants are fat soluble, they can be passed from mother to calf through milk. This has unfortunately contributed to the lack of recovery of the Southern Resident population, as first-born calves receive the highest dose of toxins and almost inevitably die. A low reproductive rate and a high infant mortality rate, both exacerbated by contaminants, mean that orca populations may continue to decline.

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Holly Fearnbach and Lance Barrett-Lennard/NOAA permit #19091

For the Southern Residents, pollution is not only in the form of chemicals. It is also underwater noise. The busy shipping channels of the Pacific Northwest reverberate with sound that can stifle the orca calls, meaning that they often have to “shout” in order to make themselves heard. This adds yet another stressor to this already imperiled population. However, laws were recently put in place by Washington State that require all vessels to stay at least 300 yards from Southern Resident orcas and at least 400 yards from the path of whales. All vessels must also reduce their speed (to 7 knots) within a half-mile of whales. In addition, the laws add some restrictions to commercial whale watching traffic, including a whale watching “no go zone” to the west of San Juan Island. This has helped to reduce at least one type of pollutant threatening this endangered population.

The orcas of the Pacific Northwest are a large and charismatic example of species whose recovery is being threatened by pollution. But there are many other species that are being killed, or whose health is being compromised, by pollution. From sea turtles and right whales becoming entangled in discarded fishing gear, to fish and seabirds with stomachs full of plastic fragments, to frogs absorbing toxic chemicals in pond water, to pesticides decimating bee and insect pollinator populations. We urgently need to reduce this flow of pollutants in order to save biodiversity.

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Jane Bullis

Establishing a National Biodiversity Strategy

The U.S. lacks a comprehensive and coordinated approach to tackling pollution and the five main drivers of the biodiversity crisis. Worldwide, 194 other countries have developed forms of a national biodiversity strategy. A national biodiversity strategy would address the extinction crisis by requiring more effective and coordinated use of laws and policies to protect biodiversity and reverse its decline, while reasserting the U.S.’ international leadership at this year’s Conference of the Parties to the Convention on Biological Diversity, happening now.

It is time for America to lead—to demonstrate how we can live in harmony with nature and to respect our environment. We cannot think of a more important roadmap toward a sustainable future than a comprehensive national biodiversity strategy. It will help us prioritize and safeguard the natural resources that are critical to humanity’s survival.

The time to invest in our planet is now, before it’s too late.