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FIGURE 1.2 Hypoxia and nitrogen loading in the Gulf of Mexico (Turner et al., 2008). (A) Annual variations in the size of the hypoxic zone in late July and the nitrate plus nitrite nitrogen loading for the preceding May. (B) Increase in the ratio of the size of the hypoxic zone relative to nitrogen loading the preceding year. The breaks in the curve reflect hurricanes and droughts, but the overall trend is highly significant.

FIGURE 1.2 Hypoxia and nitrogen loading in the Gulf of Mexico (Turner et al., 2008). (A) Annual variations in the size of the hypoxic zone in late July and the nitrate plus nitrite nitrogen loading for the preceding May. (B) Increase in the ratio of the size of the hypoxic zone relative to nitrogen loading the preceding year. The breaks in the curve reflect hurricanes and droughts, but the overall trend is highly significant.

and extending beyond the dead zone, toxic blooms of dinoflagellates like Karenia brevis occur over areas as large as the entire northwestern Gulf of Mexico.

THE OPEN OCEAN PELAGIC REALM

Myers and Worm (2003) fired a shot heard around the world when they published their controversial assertion that 90% of all of the large (average approximately ≥50 kg), open ocean tuna, billfishes, and sharks in the ocean were gone. Severe depletion of coastal and shelf fisheries was widely accepted, but the open ocean was still considered one of the last great wild places on Earth.

Exploitation

Much of the controversy revolves around the use or misuse of highly complex “state-of-the-art stock assessment methods” (Sibert et al., 2006) to estimate fisheries impacts on population biomass, size, and trophic status



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