Biology - biodiversity and human impact

what is biodiversity

the variety of genes, species, and ecosystems

why is biodiversity important

provides food, medicine, materials, ecosystem stability, recreation, and economic value

biodiversity hotspots 

regions with high biodiversity under threat of destruction 

biodiversity hotspot examples 

tropical rainforests, coral reefs, islands, and deep oceans 

percentage of endemic species in Madagascar

80%

what are coral reefs made out of

tiny animals called coral polyps that live with symbiotic algae

what causes coral bleaching

loss of algae due to heat or pollution, causing corals to lose color or die

why coral reefs are important

habitat for 25% of ocean life, protect coasts by absorbing 97% of wave energy, support fishing and tourism industries 

main threats to coral reefs

rising sea temp, ocean acidification, pollution

mass extinction

the rapid extinction of many species due to sudden environmental change

background extinction

ongoing, natural extinction at a low rate

overpopulation

when a population exceeds its carrying capacity

grasshopper effect

process where pollutants travel long distances through air and water before redepositing elsewhere

bioaccumulation

buildup of toxins in an individual organism overtime 

biomagnification

increase of toxin concentration at higher levels of the food chain 

PCBs

industrial chemicals once used in coolants/lubricants, cause hormone disruption and cancer

what does DDT cause in birds

eggshell thinning, reduced hatching success

what causes eutrophication

excess nutrients from fertilizer and waste runoff lead to oxygen depletion and fish kills

major causes of biodiversity loss

habitat destruction, species exploitation, and ecosystem disruption

leading cause of extinction

habitat destruction

ocean bottom trawling

net fishing that damages sea floor habitats and coral reefs

what happened to the passenger pigeon

once the most common U.S bird; overhunted and went extinct by 1914

overfishing

harvesting fish faster than they reproduce

exotic pet trade 

capture and sale of wild animals, threatening species (blue-throated Macaw) 

invasive species

non-native species that spread rapidly and harm ecosystems

what causes acid rain

burning fossil fuels (releases CO2 and NO2)

normal rain PH vs. US PH

normal = 5.6, US = 4.3

greenhouse effect 

CO2 and methane trap heat in the atmosphere, warming earth 

paris agreement (2015)

global agreement to limit warming below 2 degrees celsius and cut emissions by 40-70% by 2050

effects of climate change

droughts, wildfires, crop losses, disease spread, rising temperatures

what causes ozone depletion

CFCs used in coolants and aerosols destroy ozone in the upper atmosphere

ozone layer importance

blocks harmful UV radiation

what drives deforestation

agriculture, logging, mining, oil extraction

plastic bottle lifetime

450 years

microplastics

tiny fragments that enter the food chain and accumulate toxins

best solution to pollution

reduce and ban single use plastics

endangered species act (1973) 

protects listed species; supports recovery and habitat conservation

4 species removed from the ESA

bald eagle, grizzly bear, gray whale, peregrine falcon

percentage of earth covered by deep oceans

about two thirds