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GEO-6 Regional Assessment for North America


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An emerging threat to marine biodiversity is the accumulation of plastics in oceans, lakes, and rivers. While this problem has been acknowledged for many years in the context of the oceans, recent findings indicate disturbing levels of plastic microbeads in the Great Lakes and St. Lawrence Basin (Provencher 2014; Johnston 2013). Remote Arctic sea ice has already been found to contain high concentrations of microplastics, and the extent to which melting ice will release anthropogenic particulates into the ocean is not yet fully known (Obbard 2014). Microplastics have entered the food chain; they are regularly ingested by fish, birds (Figure 2.3.3) and marine mammals, and toxic bioaccumulation and, in some cases asphyxiation and starvation, often result. Microplastics emerge from a variety of sources, including microfibres from clothing put through washing machines, microbeads in body wash, shampoo, and toothpaste, the photodegradation of plastic bags, debris from car tires, and others. After several states, including Illinois, New Jersey, Wisconsin and California, moved towards phasing in a ban on microbeads in personal care products, the US government passed a law in late 2015 banning them nationwide, and the Canadian government appears prepared to take similar action. In the meantime, several large cosmetics firms have voluntarily declared they will stop using them in their products (See also discussion of marine plastics in sections 2.5.4 and 2.6.1).


Fertilizers from agriculture, phosphates from detergents and industry, and sewage from towns and cities add nutrients to aquatic systems, sometimes causing algal blooms. In recent years, algal blooms have been reported in lakes, reservoirs, ponds, rivers, swamps and estuaries in both Canada and the US. Some past successes in nutrient reductions, particularly in the Great Lakes, are now being reversed as nonpoint source runoff from growing population increases. Over the past 16 years, nitrogen has increased in 28 per cent of water bodies sampled and decreased in 12 per cent, while phosphorus has increased in 21 per cent and decreased in 29 per cent. Although harmful marine algal blooms occur naturally, they appear to be increasing in their prevalence and impacts, especially in the oceans off North America’s coasts (Lewitus et al. 2012). In the summer of 2015, for example, a record- breaking toxic algal bloom spread from the Aleutian Islands


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Figure 2.3.3: Plastics ingested by seabirds, 1969–2011


0.00 0.10 0.20 0.30 0.40 0.50


astern orth Pacic 


astern orth


Pacic  Area


ubarctic orth Pacic 


Plastics found in the digestive tracts of dead northern fulmars (Fulmarus glacialis) in the North Pacific, Canada 2011. Source: Avery-Gomm et al. 2012


to southern California, threatening wildlife and forcing some fisheries to close; unusually warm ocean temperatures are suspected.


Overexploitation, combined with other stressors such as increased temperature, decreased salinity, and increased acidity, have contributed to declines in some fish stocks in both oceans and the large northern bays. “Declining stocks include groundfish, such as Atlantic and Pacific cod, lingcod and rockfish, pelagic fish such as herring and capelin, and anadromous fish such as coho, Chinook salmon, Atlantic salmon, and Arctic char. Management measures designed to reverse longterm fisheries declines have been largely unsuccessful. Depending on the fishery, rebounds have been hampered by large-scale oceanographic regime shifts, loss of spawning and rearing habitat, and contaminants” (DFO 2010). Some fisheries are in recovery mode, such as turbot (Scophthalmus maximus), sablefish (Anoplopoma fimbria) and Pacific sardine (Sardinops ocellatus) in the West Coast


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