• commercial-word trade in endangered species fostered by huge markets
• substinence- defined as harvest of resources for food, not profit( bushmeat trade)
• incedental-byproduct of some other form of exploitation
• recreational-type of extinction resulting from human recreational activities
• indirect-due to human activities other than direct human exploitation

• 50% of fish stocks are fully exploited
• sardine stocks off California Japan
• Anchovy off Peru
• collapse of Canadian cod fishery

direct-population collapse

indirect- destruction of coral reefs, trophic web interaction

• developing models taht are explicitely, multiple species
• look at results and modify based on adaptive mgmt
• use moratorium and change season when one can fish
• better science leads to better politics

• reduces demographic success
• reduced dispersal reduces re-colonization of empty sites
• limited gene flow--- reduced genetic diversity, increased inbreeding
• dificulty locating members of opposite sex
• some species may not disperse outside preferred habitat at all

specialized diets of large-beaked insectivores of specific insects

• many tropical insectivores specialized on foraging "substrate" ex. Bicolored antbird- professional army follower
•  select habitat with dense lianas

• organisms hihger in trophic web control populations of those that are lower
• fragmentation causes loss of top predators, which can change local communities and ecosystems due to trophic cascades( top-down effects)

hard to predict. familiar example: heating item to point of combustion

reduced tree productivity in Amazon forests= climate tipping point

• low pH in rain, snow, fog, rime ice ultimately affecting ecosystems via soils and waters
• caused by sulfur and nitrogen oxides
• inhibits calcium uptake in plants
• damages gills in fish
• soil depletion

cover 1.4% of land surface

Consequences of built structures

• roads form barriers to movement
• road kills
• roads allow people access to areas where sensitive wildlife often disappear

• chlorinated hydrocarbons are pesticides persistent to break-down in environment, soluble in animal fats

birds of prey acquired high concentrations of DDT and its metabolites- populations declined throughout US due to eggshell thinning and other reproductive problems

relatively inert gases produced in large quantities by humans as refrigerants, aerosols in deodorants, etc.

effects: cuase of ozone hole. reduced egg survival. may contribute to amphibian declines

greatest threat to bioD today. deforestation is root cause of forest fragmentation.

causes deforestation ranked by importance

• substinence farming
• cattle ranching
• logging
• mining
• residential development

desertification

land degredation( and consequent loss of productivity, species diversity) in arid and semiarid ecosystems due to human activities

Causes of destertification

• overgrazing
• withdrawal of water
• cutting of woodland vegetation, climate change

consequences of destertification

• loss of unique habitat, rich in endemics
• many desert-adapted species sensitive to loss of habitat
• deserts and woodlands vulnerable to desertification relatively poorly protected by parks

these chemicals operate primarily as estrogen mimics.

examples: pesticides like DDT, dioxins, PCB's( whose action mimics sex hormones functionally)

defines as increased ecosystem productivity due to enhancement of planting nutrients.

cause: nitrates, phosphates( agricultural runoff from fertilizers, urban runoff), which enhance growth of phytoplankton and other plants

consequences: dead zones, replacements in impoundments of oligotrophic species by eutrophic ones, increased frequency red tides

habitat- the physical and biological surroundings of an organisms

habitat can by described in terms of both quantity, quality( quality determined by how well a species does demographically) source habitats have higher quality than sink habitats

• include Hg, Pb, Cd, Al, all generally toxic, depending on form
• sublethal effects in colonial wading birds: little blue herons

• mixture of fog and smoke that undergo photochemical reaction of hydrocarbons and nitrogen oxides

Effects:

• kills native vegetation
• affects coniferous vegetation in mountains surrounding LA basin
• likely cause of declining mushroom forming fungi in Europe

cascades into effects on rivers, coral reefs

occurs as a result of overgrazing and unsuitable cultivation practices

 source- high quality habitat that on average allows the population to increase

sink- very low quality habitat that cannot support a population

biotic homogenization

non-indiginous species

any species outside its native( non human influenced) geographic range.

the sequential use of multiple water bodies by boaters

demonstrated to spread Eurasian water milfoil among northern lakes

policies to check boats for aquatic weeds, clean them off, and reduce lake-hopping are underway

protection of specific natural and/or cultural features

ex. Chalmette battlefield=natural history unit

managed mainly for science/wilderness

( Adirondack park)