threats to biodiversity Flashcards
what are the direct threats to biodiversity
1) food
2) fashion
3) pets and entertainment
4) furniture and ornaments
5) traditional medicine
explain how food is a direct threat to biodiversity
- over exploitation to provide food for humans e.g.
1) Passenger pigeon (extinct)
2) cod
3) sword fish
explain how fashion is a direct threat to biodiversity
- animal skins for clothing have been used through history- however, certain species have been over exploited
1) leopards/tigers for fur coats
2) crocodiles for leather boots/bags
explain how pets and entertainment are a direct threat to biodiversity
1) pets ie parrots, lizards or tropical fish- displace them from natural habitats
2) house plants- air plants or insectivores plants
3) zoos- common to collect wild animals for zoo collections
4) aquaria- fish do not breed as successfully in captivity as conditions arent understood
how is furniture and ornaments a direct threat to biodiversity
- furniture made from tropical timber such as mahogany
- white piano keys made from elephant ivory
- corals and sea shells collected and sold as tourist souvenirs
how do traditional medicines act as a direct threat to biodiversity
- demand has led to numbers of selected species being collected desire little scientific evidence of effectiveness
1) tigers- used to cure a rage or problems ie skin diseases
2) seahorse- treat infertility, baldness and asthma
list the indirect threats to biodiversity
1) eradication of predators
2) introduced species
3) changes in abiotic factors
4) changes in biotic factors
5) habitat destruction
explain how eradication of predators is an indirect effect to biodiversity
- many species are killed beacuse they threten humans or human activities
ie
1) animals which threaten humans- sharks, poisoness snakes
2) pathogen vectors
how have changes in water availability indirectly impacted species
- land drainage of wetland has been reclaimed as farmland
- overexploitation of groundwater sources lower the water table which affects surface wetland habitats
how has dissolved oxygen indirectly impacted species
- oxygen levels decrease from hot water discharges from power stations
- oxygen levels decrease from the discharge of organic wastes such as sewage from their decomposition
- this impacts aerobic organisms reducing their survival
- drainage schemes disrupt anaerobic soils increasing nitrates pushing some species out of ranges of tolerance
how do changes in temp indirectly impact species
- changes to the distribution of species to areas more suitable or species may die out if they have nowhere to go
- hot effluent water increases water temp which can increase growth rates of vegetation, rates of decomposition etc causing deoxygenation
explain how water turbidity indirectly impacts species
- ploughing, mining, or dredging increase water turbidity
- reduces light penetration and prevent submerged plants from photosynthesising
- impact filter feeders whos gills become blocked
how does physical damage indirectly impact species
- disregarding litter or old fishing gear which causes individuals to become entangled or choke ect
what are the indirect changes in biotic factors that threaten biodiversity
1) pollinators - if insects die plants cant reproduce ie use of pesticides
2) seed dispersal - endangered herbivores species numbers decrease eg elephant = decrease plant pop
3) food chain impacts- a decline of populations may cause the increase or decrease of another
list the indirect affects on biodiversity of introduced species and examples
1) increased competition eg red and grey squirrel
2) introduced predators eg European water vole and American mink
3) introduced pathogens eg squirrel pox from the grey squirrel
4) species hybridization - changes to natural gene pool eg wildcat pop threatened by a domestic cat
5) loss of species that control abiotic factors eg beavers build damns which control water flow
