3.2: Human Imapct On Biodiversity Flashcards
(8 cards)
Invasive alien species case study: gray squirrel invasion in the UK
Gray squirrels -> introduced to UK from North America in 19th century
-> originally brought as ornamental additions to estates -> become major invasive species
IMPACT:
Outcompete native red squirrels for resources (food, habitat, etc)
Carry squirrel pox virus -> fatal to red squirrels but gray squirrels have resistance
MANAGEMENT STRATEGIES:
Culling programs: reduce gray squirrel populations, restore red squirrels and restore native biodiversity
Forest management: selective tree planting, creating corridors -> more favorable conditions for the native species (red squirrels more arboreal than gray)
Research and monitoring: continual research + monitoring of squirrel populations + their impacts -> help develop effective management strategies
Extinct due to human activity: Caribbean Monk Seal
First discovered by Columbus in 1494
Before exploitation population of: 233,000 - 338,000
Columbus: hunted for food
1600s: hunted to use oil to lubricate machinery on sugar plantations, for display
1880s: very rare but stronghold in Keys west of Yucatan
1915: 200 were killed there
1952: Last reliable record: small colony at serranilla Bank
1973: aerial survey -> no seals
1980 and 1984: vessel surveys -> no seals
1986: approx. date of extinction
NICHE:
Unknown, likely regulated fish populations
HABITAT: Caribbean, Mexico, United States
FACTORS LEADING TO EXTINCTION:
Ecological: overfishing of prey, habitat degradation, natural vulnerability due to isolated population.
Social: hunted for food+skin+oil, tourism, human disturbance
Political: lack of legal protection, delayed conservation efforts/persecution
CONSEQUENCES OF ITS EXTINCTION:
Ecosystem: Disruption of food chain -> were top predator -> overpopulation, loss of biodiversity -> reduced resilience, ecosystem shifts
Humans: loss of scientific value + tourism potential, loss of culture, warning signs for dangers of human activity
Critically endangered species: Javan Rhinoceros
Current population estimate:
68 (29 males, 24 females, 15 kiddies)
None currently in captivity
68 in Ujung Kulon National Park
-> 33% of adults might breed
-> population not increased significantly over last 20 years
—> changes in park habitat, competition, humans
GEOGRAPHICAL RANGE:
Currently only in Indonesia
Previously in Bangladesh, China, Cambodia, India, Laos, Malaysia, Myanmar, Thailand, Vietnam
HABITAT: lowland tropical rainforest in vicinity of water
-> previously more open mixed forest, but do it its rarity preferred habitat not known
NICHE: mega herbivore -> control growth of certain plants
FACTORS THREATENING POPULATIONS:
Ecological:
invasive plant species -> dominate habitat -> prevent growth of food
Competition for food -> Javan banteng
Disease transmission from cattle
Natural disasters
Social:
Illegal hunting/poaching (demand in traditional medicine)
Human encroachment
Poison fishing -> indirectly harm rhino + ecosystem
Agriculture and aquaculture (annual and perennial non-timber crops)
Biological resource use (hunting, logging)
Political:
Limited habitat protection -> confined to 1 national park
Inadequate enforcement of laws
Slow habitat management efforts
Critically endangered species: Javan Rhinoceros
CONSEQUENCES OF ITS EXTINCTION:
Ecosystem:
Loss of biodiversity
Disruption of ecological balance: big role in shaping vegetation structure/composition -> extinct -> overgrowth
Humans:
Cultural impact: cultural significance in Indonesia
Scientific loss: species offer insight into evolutionary biology, ecology, etc.
Indicator of environmental health: loss could signal broader issues
CONSERVATION EFFORTS:
In-place conservation efforts: legally protected in Indonesia and under CITES since 1975
Protected and monitored by park authorizes, WWF, YABI
5 rhino proteciton units in the national park
Systemic camera trap monitoring + DNA analysis for tracking
No poaching reported since 1970s
91% of population protected in designated area
Invasive Arenga palm removal efforts ongoing
Conservation planning and policy:
National rhino conservation strategy and action plan (2007-2017) guide efforts
2015 -> population and habitat viability assessment -> emphasize critical threat of poaching
Inter/national laws -> support protection, trade restriction, compliance enforcement
Conservation sites identified and managed
Species management:
No harvest or reintroduction program yet
No ex-situ conservation/breeding program
Education and awareness:
Active education and awareness programs in place
Subject to international trade controls + management agreements
Recovered/recovering species (species whose conservation status has improved due to human intervention): Island Fox
Current population estimate:
4,001 mature individuals
Current conservation status: near threatened
Previous conservation status: critically endangered
1990s-2000s -> severe decline:
Declined drastically on 5/6 Channel Islands (1990s)
2002: total number from 6k -> 1.5k
Captive breeding and recovery:
San Miguel, Santa Rosa, Santa Cruz Island’s -> dropped to 15-50 individuals
2003: Captive breeding program -> significant recovery by 2011
Santa Catalina:
1999 canine distemper outbreak -> almost wipe eastern population
Translocations efforts -> 1.5k by 2011
San Clemente:
Population steadily grew from 250 adults (2001) to 700 adults (2011)
Highest density -> stabilized dune habitats
Population monitoring:
Estimates based on capture-recapture methods
HABITAT:
Forest/shrubland/grassland/marine intertidal habitat
NICHE:
Habitat generalist, omnivorous, disperse seeds
Keystone species but has some predators
Recovered/recovering species (species whose conservation status has improved due to human intervention): Island Fox
FACTORS THREATENING POPULATIONS:
ECOLOGICAL:
Predation by invasive species: golden eagle
Disease outbreaks: canine distemper virus
Low genetic diversity: reduce ability to adapt + increase vulnerability to disease
Naturally small population size: more susceptible to extinction from changes in
SOCIAL:
Introduction of invasive species: tied to human activities (boating, habitat changes)
Potential disease introduction from human movement or domestic animals
Public stakeholder conflict: previous management focused on the Island Shrike -> risk to foxes
POLITICAL:
Longterm dependence on conservation: considered conservation reliant species -> requires ongoing government support
Risk of inadequate future policy or monitoring: relation in management -> new threats
HUMAN INTERVENTIONS:
RESEARCH AND MONITORING:
Systemic monitoring programs across all islands
Population/mortality data used to assess extinction risk
Periodic testing for disease exposure
Tracking via radio collars/capture-recapture studies
Federally listed as endangered (US endangered species act)
Formation of island fox conservation working group
CAPTIVE BREEDING AND REINTRODUCTION:
Emergency captive breeding program
In-situ breeding -> prevent disease exposure
Over 300 released 2001-2008
Wild reproduction eventually outpaced captive efforts
DISEASE MANAGEMENT:
Vaccination programs against canine distemper virus + rabies
Vaccinated core strategy -> natural immunity while protecting key populations
Epidemic response plan created
INVASIVE SPECIES CONTROL:
Golden eagle relocation
Feral pig and deer removal
Reintroduction of bald eagle -> restore ecosystem balance
HABITAT AND ECOSYSTEM RESTORATION:
Removal of non-native species -> native vegetation
Address vegetation degradation (due to sheep grazing)
Support re-establishment of island habitat complexity
EDUCATION AND OUTREACH:
Programs implement to engage public and stakeholders
IMPACT OF INTERVENTIONS:
Population recovery:
2012:
San Miguel: ~400 adults
Santa Rosa: ~500 adults
Santa Cruz: >900 adults
Santa Catalina: >1,500 individuals (total)
All subspecies approaching/reaching pre-decline levels
Reduced predation:
Golden eagle removed -> increased survival rates
Disease prevention:
No major outbreak since implementation of CDV + rabies vaccination programs
Vaccinated flow-> antibody levels consistent with protection
Stable wild populations:
All captive foxes -> released 2008
Population now self-sustaining
Improved ecosystem health:
Habitat quality + ecological balance improved via removal of invasive species + rewilding efforts
Model for conservation:
Conservation success story -> effectiveness of intensive, collaborative recovery strats
The tragedy of the commons: the Pinta Island Tortoise
Extinct
Habitats: beaches in Galapagos, Ecuador
Life expectancy: 150 years
Size: 1.5 m, 230 kg
Diet: herbivorous
No known predators, one of largest tortoises in recorded history
LONESOME GEORGE:
The last known pinta island tortoise
Died in 2012 -> official extinction of the subspecies
Despite trying no other individuals found, attempts at breeding him failed
HUMAN ACTIVITY:
1800s: whalers + settlers collected them for food
-> easy to capture
-> require little care
-> survived long voyages
No regulation -> people took as many as they wanted -> tragedy of the commons
Also introduce invasive species (eg goats) -> destroyed vegetation and food sources
Other species preyed on eggs, livestock damaged tortoises habitats
=> extinction in the wild
REDUCTION IN BIODIVERSITY:
Herbivores, seed dispersers -> shaped island vegetation
-> their loss -> disrupt plant communities + balance
Invasive species further lower biodiversity
Loss of tortoise affect water flow, fire patterns, increased charcoal levels, etc.
TRAGEDY OF THE COMMONS:
No specific government govern tortoises -> shared resource
Hunting + invasive species -> population depleted over time
-> took tortoises because if they didn’t someone would
-> key principle of tragedy of commons
Habitat loss also due to invasive species + lower genetic diversity -> lower resilience
ACTIONS ATTEMPTED:
Captive breeding program: increase population of related subspecies
Invasive species removal: non-native species removed -> restore natural habitats
Rewilding efforts: 2010 - tortoises from similar populations were introduced to take over their role
Genetic research: hybrid tortoises with partial pinta ancestry discovered -> selective breeding efforts
Ongoing restoration: continuous monitoring of vegetation, invasive species, tortoise populations -> long term conservation
The tragedy of the commons: Gulf of Mexico dead zones
Dead zone: an area where there is little to no oxygen and therefore is incapable of supporting life
Many farms in central USA -> fertilizer
Heaven rain -> runoff -> Mississippi River -> Gulf of Mexico
-> fertilizer creates dead zones via eutrophication
EFFECT ON BIODIVERSITY:
Loss of habitat: low oxygen conditions -> environment cannot support animals/plants
-> immobile animals likely to die
Food webs: due to migration out of dead zones -> food web in dead zone and in new area disturbed
CONSERVATION EFFORTS:
Sustainable farming techniques: switching from harmful techniques (monoculture, excessive tillage) to techniques like cover cropping -> nutrients added absorb fully -> no leaching/runoff
Nutrient management plans: using + applying fertilizers with plan -> farmers minimize runoff -> reduce dead zones
Policy and programs: government led initiatives -> Environmental Protection Agency’s request to develop strategies to reduce runoff for financial incentives
-> encourage farmer to develop plans to minimize runoff + excessive fertilizers
THE TRAGEDY OF THE COMMONS:
Farmers utilize fertilizers without consideration of larger effects beyond immediate area
All farms use fertilizers -> large amount of runoff through Mississippi River -> Gulf of Mexico -> fast buildup of chemical pollution/eutrophication -> unnaturally high rate of dead zones -> large effect on biodiversity of the region
