nomic groups combined based on multivariate ordination varied roughly 2-fold among the 12 regions, from ≈43% in the Bay of Fundy to 74% in the Adriatic, but the trajectories and patterns of degradation were strikingly similar for all of them (Lötze et al., 2006). Most of the mammals, birds, and reptiles were severely depleted by 1900 and had declined even further by 1950. Among fish, diadromous salmon and sturgeon were depleted first, and then groundfish and large pelagics like tuna and sharks, and finally small pelagics like herring, menhaden, and sardines.
Oysters were the first invertebrates to suffer extreme depletion, and the massive destruction of oyster reefs by dredging has permanently destroyed much of the formerly great habitat complexity of estuaries and coastal seas worldwide (Jackson et al., 2001; Kirby, 2004; Lötze et al., 2006). Depletion of oysters moved progressively farther and farther from major markets like New York City, San Francisco, and Sydney, until eventually all of the stocks along eastern and western North America and eastern Australia had collapsed (Kirby, 2004). None of these wild stocks have substantially recovered because of eutrophication, disease, and habitat loss as described below, and oyster production now depends almost entirely on aquaculture.
Today, most fish and invertebrate stocks are severely depleted globally, and one-half to two-thirds of global wetlands and seagrass beds also have been lost (Table 1.1). Of the 80 species surveyed, 91% are depleted, 31% are rare, and 7% are extinct (Kirby, 2004). Nowhere are there any substantial signs of recovery, despite belated conservation efforts, except for nominal increases in some highly protected birds and mammals.
Beginning in the 1950s, accelerating increases in the number of introduced species and degradation of water quality due to excess nutrients from the land have surpassed fishing as the major factors in the degradation of estuaries and coastal seas, although fishing still plays a major role (Jackson, 2001; Jackson et al., 2001). Numbers of introduced species in the five best-studied estuaries range from 80 to 164 (average 117) species, where they have commonly displaced native animals and plants to become the dominant species. Geochemical and paleobotanical evidence of eutrophication in cores is readily apparent since at least the 19th century due to deforestation and agriculture, with consequent runoff of sediments and nutrients (Zimmermann and Canuel, 2002; Colman and Bratton, 2003; Lötze et al., 2006). These effects were aggravated by the extirpation of suspension feeders like oysters and menhaden (Jackson, 2001; Jackson et al., 2001). The situation then largely stabilized until about 1950 when new influxes of nitrogen fertilizers began. Today, most of the estuaries