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Topic 12 The Biodiversity Crisis Why Should We Care About Biodiversity? Use Value Economic profits Medicinal sources Ecological services Nonuse Value Aethetics Enjoyment Cultural inspiration Ecosystem Services This is the idea that nature provides many services beyond economic goods that are not accounted for: Gas regulation Water purification Waste remediation Nutrient cycling Soil formation Etc…. Worth $16-54 trillion US dollars, on average $33 trillion (Costanza et al. 1997) Biodiversity & ecosystem functioning Ecological communities with higher biological diversity are more resilient* and stable** than those with low biodiversity. Both species and functional diversity levels are important factors in maintaining ecological communities. Species diversity: the number of different species it contains (species richness) combined with the abundance of individuals within each of those species (species evenness). Functional diversity: the number of different species performing specific roles in the community (eg diversity of primary producers or decomposers) *Resiliency is the ability to recover from a disturbance. **Stability refers to the maintenance of trophic levels and interspecific interactions. Cenozoic Era Period Millions of years ago Quaternary Today Bar width represents relative number of living species Extinction Species and families experiencing mass extinction Current extinction crisis Tertiary 65 Extinction Cretaceous Mesozoic Cretaceous Jurassic 180 Extinction Triassic Triassic 250 Extinction 345 Extinction Permian Paleozoic Carboniferous Permian Devonian Devonian Silurian Ordovician Cambrian 500 Extinction Ordovician Fig. 4-12, p. 93 The Biodiversity Crisis Endangered & Threatened Species AT RISK SPECIES Some species have characteristics that make them vulnerable to ecological and biological extinction. Generalist and Specialist Species: Broad and Narrow Niches SPECIES GONE OR AT RISK The International Union for the Conservation of Nature and Natural Resources (IUCN) publishes an annual Red List They place species into 9 categories The 2010 Red List contains 18,351 species at risk for extinction out of 55,926 evaluated (33%). SPECIES EXTINCTION Species can become extinct: Locally Ecologically Globally (biologically) Global Extinction Some animals have become prematurely extinct because of human activities. Dodo Steller’s sea cow SPECIES AT RISK Percentage of various species types threatened with premature extinction from human activities. U.S. STATS Threatened species by broad taxonomic grouping: Mammals: 37 Birds: 74 Reptiles: 32 Amphibians: 56 Fishes: 177 Molluscs: 273 Other Invertebrates: 258 Plants: 245 U.S. FWS Reasons for biodiversity loss HIPPO H:habitat destruction and degradation I: invasive species P: population growth in humans P: pollution O: overexploitation H: habitat degradation or loss Terrestrial Deforestation Loss of grasslands Aquatic and marine Benthic habitat loss Erosion Eutrophication TROPICAL DEFORESTATION Why Should We Care about the Loss of Tropical Forests? HABITAT LOSS, DEGRADATION, AND FRAGMENTATION EXAMPLES Commercial fishing BEFORE AFTER I: invasive species Non-native species Not all exotics are invasive Characteristics of invasives Many invasive species have qualities that make them successful in novel environments Also depends on qualities of the habitats they are introduced to © US FWS Zebra mussel ~2 months ecological & economic damage Zebra mussel impacts Negative Decreased populations of native shellfish Altered water chemistry Disruption of trophic dynamics Positive Increased water clarity Increased light penetration into water column Increased photosynthesis Increased populations of some other organisms Cane toad (Bufo marinus) P: pollution Terrestrial Acid deposition Toxic dump sites Litter Pesticides Inorganic fertilizers Tropospheric ozone Aquatic and marine Cultural eutrophication Pollutant deposition and leaching Litter Pollutant Impacts: Litter Pollutant Impacts: Nutrient loading Pollution Each year pesticides are estimated to kill: Kill about 1/5th of the U.S. honeybee colonies. 67 million birds. 6 -14 million fish. And to threaten 1/5th of the U.S.’s endangered and threatened species. Peregrine Falcons: a success story O: overexploitation Hunting Commercial fishing OVEREXPLOITATION Figure 11-16 Over-fishing: About 75% of the world’s commercially valuable marine fish species are over fished or fished near their sustainable limits. Big fish are becoming scarce. Smaller fish are next. 30% of the fish that are caught are discarded. Bycatch Tragedy of the Commons Some resources are widely available and owned by no one (or everyone, depending on your perspective). Many fisheries operate by the concept “if I don’t take it, someone else will”. (A) Trajectories of collapsed fish and invertebrate taxa over the past 50 years (diamonds, collapses by year; triangles, cumulative collapses). Data are shown for all (black), species-poor (<500 species, blue), and species-rich (>500 species, red) LMEs. Regression lines are best-fit power models corrected for temporal autocorrelation. (Worm et al 2006, Figure 3A) Local examples Figure 1. Frequency distributions of maximum known declines among marine fish populations over periods of at least 10 years, shown (a) for all 232 populations (the median decline of 83% is identified by a vertical line) and for 3 families: (b) Clupeidae (n = 56, median decline = 91%; includes Atlantic herring, Clupea harengus); (c) Gadidae (n = 70, median decline = 80%; includes Atlantic cod, Gadus morhua, and haddock,Melanogrammus aeglefinus); and (d) Pleuronectidae (n = 30, median decline = 74%; includes flatfishes such as flounder, sole, and halibut). Hutchings and Reynolds 2004 Fish farming in cage Trawl flap Trawler fishing Spotter airplane Sonar Purse-seine fishing Trawl lines Trawl bag Long line fishing Fish school Drift-net fishing Float Buoy Lines with hooks Deep sea aquaculture cage Fish caught by gills Fig. 12-A, p. 255 Shark finning Bycatch Incidental capture of non-target aquatic animals in fishing operations (commercial or recreational) Discards in US Fisheries (2002) FISHERY DISCARD WEIGHT (mt) DISCARD RATE SPECIES SEUS, G. of Mexico shrimp trawls 507,845 4.39 Snappers, mackerel, Atlantic croaker, crabs, porgies, menhaden Northeast groundfish fishery 97,688 1.79 Spiny dogfish, skates, butterfish, monkish, hake West coast groundfish fishery 23,297 0.88 Flatfish, skates, halibut, whiting, sharks Source: Harrington et al., 2005 Global Discards (1992-2001) Source: Kelleher, 2005 Commercial whaling: another tragedy of the commons 1925-1975 1.5 million whales killed 8 of 11 major species reduced to levels not profitable to hunt any more Commercial whaling Current pop. sizes: Humpbacks 10,000 Fin 56,000 Minke 149,000 Blue 10,000 Pre-exploitation pop. sizes: Humpbacks 240,000 Fin 360,000 Minke 265,000 Blue 200,000 Roman & Palumbi 2003 International Policies International Convention for the Regulation of Whaling, 1946 to regulate global whale stocks (est.’d the IWC) Mission was to set sustainable quotas Moratorium 1986 (US ended commercial whaling in 1970) Commercial Whaling Despite ban, Japan, Norway, and Iceland kill about 1,300 whales of certain species (minke, fin, humpback) for “scientific purposes”. Figure 12-5 Lake Victoria Whooping cranes: a fledgling success story Whooping Crane Cons. Assoc. Current Whooping Crane population: Wild #: 407 (99 pairs) Captive #: 167 (34 pairs) Source: Whooping Crane Conservation Association P: human population growth