decline populations scientists observed reduction populations european species 1950s awareness decline populations classification modern day global mass extinction dates 1980s species frogs present continents decline today phenomenon declining populations affects thousands species types ecosystems recognized severe examples extinction severe implications global biodiversity 1980s decreases populations including population crashes mass localized spotted locations world declines known critical threats global biodiversity causes believed involved including disease habitat destruction modification exploitation pollution use introduced species radiation causes declines poorly understood topic currently subject ongoing research calculations based extinction rates suggest current extinction rate amphibians times greater background extinction rate estimate goes times endangered species included background past decades declines populations amphibians class organisms includes frogs occurred worldwide results published worldwide assessment populations global assessment found species globally threatened experiencing form population decrease species extinct iucn red list incorporates subsequent updates lists species critically endangered despite high risk group faces recent evidence suggests public growing largely indifferent environmental problems posing problems environmental workers alike habitat loss disease climate change thought responsible drastic decline populations recent years declines particularly intense western united_states central_america south_america eastern australia fiji cases appeared worldwide human activities causing loss world biodiversity amphibians appear suffering greater effects classes organism amphibians generally staged life cycle consisting aquatic larvae terrestrial adult phases sensitive terrestrial aquatic environmental effects skins highly susceptible environment organisms birds mammals scientists believe amphibians serve coal declines populations species indicate groups animals plants soon risk declines populations widely recognized late 1980s large gathering reported noticing declines populations amphibians globe species golden endemic costa_rica featured prominently subject scientific research populations suddenly crashed disappeared completely species including disappeared time species located related local human activities raised particular concern initial declines presented conservation issue late 1980s scientists remained reality gravity conservation issue argued populations organisms amphibians included naturally vary time argued lack long term data populations difficult determine declines reported worth limited time money conservation efforts initial come consensus declines populations real severe threat biodiversity consensus emerged increase number studies monitored populations direct observation mass mortality sites lacked apparent cause awareness declines populations truly global nature potential causes numerous potential explanations declines proposed causes associated population declines cause likely affect certain circumstances causes declines understood appear affect groups organisms amphibians causes include habitat modification introduced predators competitors introduced species pollution use harvesting declines occurred habitats effects likely occur causes declines complex attributed emerging diseases climate change increased radiation long distance transmission chemical wind artificial lighting suggested potential cause insects attracted lights making habitats habitat modification habitat modification destruction dramatic issues affecting species worldwide amphibians generally need aquatic terrestrial habitats survive threats habitat affect populations amphibians vulnerable habitat modification organisms require habitat type large scale climate changes modifying aquatic habitats preventing amphibians spawning altogether habitat habitat occurs habitats isolated habitat modification small area forest completely surrounded agricultural fields small populations survive fragments susceptible genetic drift extinction small fluctuations environment pollution chemical evidence chemical causing frog developmental extra limbs eyes varying effects frogs alter central nervous system like cause disruption production experimental studies shown exposure commonly greatly increase mortality additional studies indicated terrestrial adult stages amphibians susceptible non active ingredients particularly shown cause male african frogs development male female organs reported parts world study conducted laboratory sweden frogs exposed levels like existing natural bodies water europe united_states females exposed weakest concentration twice likely females control group given heaviest dose female effects likely local restricted areas near agriculture evidence sierra nevada mountains western united_states traveling long distances areas including california recent evidence points possible contributing factor worldwide decline amphibians radiation cloud cover like organisms increasing radiation factors harm dna amphibians particularly eggs damage depends life stage species type environmental parameters frogs produce dna damage susceptible effects loss layer exposure radiation kill particular species life stage cause damage dozen species amphibians studied severe effects reported publications peer reviewed journals representing authors north_america europe australia experimental enclosure approaches determine effects egg stages criticized example egg masses placed water depths shallower typical natural sites radiation important amphibians effect egg stage climate change likely exerted major effect declines example cloud forest series unusually warm years led mass frog golden increased level cloud cover result global warming warmed nights cooled daytime temperatures blamed growth fungus agent fungal infection immediate cause die offs climate change played pivotal role researchers included subtle connection inclusive climate linked epidemic hypothesis acknowledged climatic change key factor costa_rica new evidence shown global warming capable directly body condition additionally phenomenon landscape alteration pollution species invasions effect disease number diseases related mass die offs declines populations amphibians including red leg disease family entirely clear diseases suddenly begun affect populations evidence suggests diseases spread humans combined environmental factors considerable evidence parasitic type contributed developmental population declines amphibians regions genus complex life cycle host species host includes number species aquatic early stages transmitted aquatic larvae developing limb life stages produce developmental post frogs including additional missing limbs increase frog predation aquatic birds final host study showed high levels nutrients farming activities fuel parasite caused frog ponds lakes north_america study showed increased levels nitrogen cause sharp abundance parasites subsequently form developing limbs causing missing limbs extra limbs severe including extra limbs following large scale frog deaths australia central_america research teams areas came identical results previously species fungus clear recent amphibians australia americas linked fungus fungus belongs family known generally disease caused called frogs infected disease generally skin believed death occurs interference skin functions including maintenance fluid balance role barrier time infection death found weeks experimental tests infected animals carry fungus long days transmission fungus subsequent research established fungus present australia present north_america 1970s known record infection frogs sold pet shops laboratories world possible fungus exported africa introduced predators non native predators competitors found affect viability frogs habitats mountain yellow legged frog typically inhabits sierra nevada lakes seen decline numbers non native fish trout recreational fishing developing fall prey fish large numbers interference frog year causing decline manifest ecosystem increased noise levels frogs highly vocal reproductive behaviour involves use suggestions increased noise levels caused human activities contributing declines study thailand increased ambient noise levels shown decrease calling species cause increase shown cause widespread decline symptoms stressed populations populations beginning stages decline number signs potentially identify risk segments conservation efforts sign developmental instability proven evidence environmental stress environmental stress potentially raise diseases lead declines study conducted queensland australia example populations species found exhibit far greater levels limb pre decline years control years preceded die offs average years learning identify signals critical period population declines occur greatly improve conservation efforts conservation measures february scientists worldwide met atlanta form group called help save species amphibians disappearing starting captive breeding programmes conservation efforts created organizations help studies frog extinction educate people issue hand areas noticed frog like australia policies created prevent extinction species local initiatives placed conscious efforts decrease global warming turn conscious effort saving frogs south_america increased decline populations set policy try save frogs suggestions include getting entire governments place set rules institutions source guidelines local governments critical issue design protected areas amphibians provide suitable conditions survival conservation efforts use protected areas shown generally temporary solution population decline extinction amphibians crucial amphibians maintain high level genetic variation large diverse environments education local people protect amphibians crucial legislation local protection limiting use toxic chemicals including sensitive areas
Decline in amphibian populations