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“The Loss of Diversity Causes and Consequences” Primary cause of the loss of diversity: habitat destruction habitat alteration habitat fragmentation Organisms have specific habitat requirements (abiotic and biotic) such as light moisture, temperature etc. Thus habitat modification and destruction and the extinction or extirpation of populations and species goes hand in hand. Genetic dilution (increased genetic homozygosity) Loss of genetically distinct populations within species is important – example trout and otters “The Loss of Diversity Causes and Consequences” Over exploitation of species – over fishing overharvesting of plants and animals passenger pigeon, bison, sturgeon Introduction of invasive species - species that have no natural predators or disease that out compete native species for resources. Dutch elm disease – elm bark beetle introduced fungus from europe and asia. Asian or silver carp http://www.wlfi.com/dpp/sports/outdoors/local-wlfilafayette-whats-being-done-about-asian-carp Mile a minute weed - Persicaria perfoliata introduced from asia Red Knots feeding in Delaware “The Loss of Diversity Causes and Consequences” Interrelatedness of species within ecosystems and between ecosystems. Horseshoe crabs and Red Knot as an example Red Knots are a shore bird that overwinter in Argentina and southern South America then fly 10,000 miles to the high arctic to breed in the spring and early summer to breed. They rely on horseshoe crab eggs as their source of energy to complete the journey and have enough energy to breed. What happens if there is decrease in the horseshoe crab population? What else are they used for? “The Loss of Diversity Causes and Consequences” Direct human use of global Net primary productivity (NPP) currently exceeds 3% and 4% on land. Indirect share of the unreduced (consumed or altered) global NPP exceeds 40% Can our species use 2/5 or more of the earth’s NPP and expect systems to remain stable? What does this suggest as human populations grow? “The Loss of Diversity Causes and Consequences” Can we turn to earth’s oceans? Currently we use in excess of 2% of the NPP of the sea. Resources are not concentrated and thus are difficult to harvest. People cannot efficiently harvest NPP from the sea because it is in the form of zooplankton and phytoplankton. Light penetration is limited. Photic zone is first 100 meters where 70% of earth’s photosynthesis takes place. 90% of ocean is aphotic – depths greater than 1000 meters no measurable light. Lack of nutrient availabiltiy. Nutrient lost to deep ocean sediments (nutrient sink).
