What Are the Major Threats to Aquatic Biodiversity? Habitat loss Invasive species Pollution Climate change Overexploitation … All in the “face” of the growing HUMAN POPULATION.

Natural Capital Marine Ecosystems Ecological Services Economic Services Climate moderation Food CO2 absorption Animal and pet feed Nutrient cycling Pharmaceuticals Waste treatment Harbors and transportation routes Reduced storm impact (mangroves, barrier islands, coastal wetlands) Coastal habitats for humans Figure 8.5: Marine systems provide a number of important ecological and economic services (Concept 8-2). Questions: Which two ecological services and which two economic services do you think are the most important? Why? Recreation Habitats and nursery areas Employment Oil and natural gas Genetic resources and biodiversity Minerals Building materials Scientific information Fig. 8-5, p. 172

Habitats for many species Transportation corridors Natural Capital Freshwater Systems Ecological Services Economic Services Climate moderation Food Nutrient cycling Drinking water Waste treatment Irrigation water Flood control Groundwater recharge Hydroelectricity Figure 8.15: Freshwater systems provide many important ecological and economic services (Concept 8-4). Questions: Which two ecological services and which two economic services do you think are the most important? Why? Habitats for many species Transportation corridors Genetic resources and biodiversity Recreation Scientific information Employment Fig. 8-15, p. 181

900,000 800,000 700,000 600,000 500,000 Fish landings (tons) 400,000 1992 300,000 Figure 11.7: Natural capital degradation. This graph illustrates the collapse of Canada’s 500-year-old Atlantic cod fishery off the coast of Newfoundland in the northwest Atlantic. Beginning in the late 1950s, fishers used bottom trawlers to capture more of the stock, reflected in the sharp rise in this graph. This resulted in extreme overexploitation of the fishery, which began a steady decline throughout the 1970s, followed by a slight recovery in the 1980s, and then total collapse by 1992, when the fishery was shut down. Despite a total ban on fishing, the cod population has not recovered. The fishery was reopened on a limited basis in 1998 but then closed indefinitely in 2003 and today shows no signs of recovery. (Data from Millennium Ecosystem Assessment) 200,000 100,000 1900 1920 1940 1960 1980 2000 Year Fig. 11-7, p. 257

Deep sea aquaculture cage Fish farming in cage Trawler fishing Spotter airplane Purse-seine fishing Sonar Drift-net fishing Long line fishing Float Buoy Figure 11.8: This diagram illustrates several major commercial fishing methods used to harvest various marine species (along with methods used to raise fish through aquaculture). These fishing methods have become so effective that many fish species have become commercially extinct. lines with hooks Deep sea aquaculture cage Fish caught by gills Fig. 11-8, p. 259