Biol 367: Lecture 6: Climate Change: The Mother of All Threats?

Where is temperature change most pronounced?

The polar latitudes

What is CO2 associated with?

• Global warming

• Anthropogenic activity

How do we find evidence of historic CO2 and temperature change?

Bubbles in Antarctic ice cores show trends in CO2 and temperature over time → They are both increasing!

What are two changes associated with climate change?

• Increased precipitation (on average)

• Increased severity of weather events

Where is climate change most pronounced?

• Coastal regions

• Tropical regions

What are difficulties with displaying direct evidence of climate change?

• Difficult to show; often descriptive

• Show cause-correlation confusion/skepticism/denial

• Rebut with evidence via meta-analyses

What are 6 effects of global warming?

1. Increased temperatures and incidence of heat waves

2. Melting glaciers and polar ice

3. Rising sea level

4. Earlier spring activity

5. Shifts in species range

6. Population declines

How are polar bears effected by climate change?

Polar Bear Population Decrease

Correlated with changes in ice cover, temperature, habitat and resources

• Less ice = less hunting habitat

• Less cold = less denning habitat

• Less habitat = fewer resources

• Fewer resources = fewer bears

What is the most important determinant of whether or not habitat loss generated biodiversity loss?

• Highest monthly temperature

• Change in precipitation

What happens if If effects of Habitat loss + Climate change > effects individually?

Current conservation management strategies may be ineffective and inefficient

How is current climate and clmate change important factors for habitat loss?

Important factors determining the negative effects of habitat loss on species density and or diversity

• Current temperature is the most important determinant of habitat loss and fragmentation

What is a Meta-analysis via Systemic Review?

• Rigorous, comprehensive search

• Transparent inclusion criteria

• Compares apples - apples

• Creates weight of evidence

What are some examples of the syngeistic effects of climate change?

• Ocean acidification, warming and sea level rise

• Shifting species ranges + habitat loss / fragmentation

What are some examples of over exploitation?

• Overfishing

• Exotic animals as pets

• Trophy hunting

What is the Allee effect?

An ecological phenomenon where an individual's fitness or the population's per capita growth rate has a positive correlation with population size or density

What are some groups that experience exasterbated rates of over exploitaton?

• Primates

• Birds

• Reptiles

• Ordamental fish

• Reef corals

• Orchids

• Cacti 

• Trees

How do species self-regulate population

When populations are high there is increased competition for resources such that death rate is high and birth rate is low

This occurs because resource availability limits growth rate so species reach a max population size AKA carrying capacity

What is maximum sustainable yield?

amount of population that can be taken in perpetuity. The largest yield/catch that can be taken from a species stock over an indefinite period of time.

How is MSY used in traditional population management?

Traditional population management considers the stock of individuals species as a single biological unit, rather than as components of a larger ecosystem

Each stock is managed to bring in a maximum economic return, overlooking the need to leave behind a certain portion to continue its ecological role in the ecosystem

How did the use of MSY in fisheries cause a popultion crash?

• Used data to build a logistic harvesting model

Determined MSY to be ~10 million tons / year

Based on quota harvesting strategy & ‘average’ environmental conditions

But in 1972 environmental conditions disappeared; El Nino caused warmer temperatures and lower productivity of fish populations

= As a result MSY was too high!

Fisheries collapsed, and took over 20 years to recover

This demonstrates the fragility of assumptions that populations are in equilibrium and the average conditions never change

Why do Africans rely on Bushmeat?

• Hunting of wild animals is universal

• People have always relied on fish + game

• Bushmeat continues to be a primary source of protein for many Africans because  of limited alternatives

An estimated 30-80% of population gets protein from bushmeat

What are the causes of a growing bushmeat trade? how did it become a multimillion dollar industry?

• Poverty

• Food insecurity

• Increased access

• Increased demand in cities

• Few protein and income alternatives

• Ineffective policy and law enforcement

• Limited awareness 

What is the solution to the bushmeat trade?

We need to build a concerted effort that addresses not only the need to protect existing wildlife population but also to alleviate the potential human tragedy resulting from the economic factors driving the system

What are some examples of potential solutions to the bushmeet trade?

• Youth involvement in wildlife management

• Provision of alternative livelihood

• Learn about health risks of eating Bush meat

• Use of cultural values like Taboos and Totems related to wildlife

• Exploring ecotourism and Research potential

What are the cumulative effects of the bushmeet trade?

More people, more consumption = less chance of being sustainable

Expanding to countries and species not previously at risk due to an increase in commercial logging and associated roads

Roads + trucks link wilderness and hunters to cities and consumers

Local people getting more advances weapons as gain profit from bushmeat sales due to low costs

What are the individual ffects of the bushmeat trade?

• Loss of culture: Taboo, Norms and Totems

• Risk of contracting diseases like Ebola, Anthrax, Marburg Fever, East Coast Fever, SIV and TB

What is fishing down the foodweb?

As "resource" becomes extinct the market turns to another species until diminishing returns

→ We are eating our way through oceans

What is the tragedy of the commons in fisheries?

It is in each fishers interest to catch as many fish as possible even if the commons is damaged as a result

The fisher receives all the benefits from additional fish, but damage to the commons is shared by the group

If all fishers make this individually rational decision, the commons is destroyed and all the fishers suffer at the end

Individuals do not stop fishing until the costs outweigh the benefits

What are the global losses encurred from invasive species?

• 1 trillion/ year globally

• In Canada the ECCC estimated annual lost revenue caused by just 16 invasive species is $13-35 billion

• Damage, management and mixed costs

How did local ivasive fragment forests in Queensland Australia?

• Greater abundance of native IIiana species

• Greater impact on adjacent trees; altered composition and canopy = altered biodiversity

How does disease effect biodiversity?

Contributes directly to population decline but rarely causes extinction (3%)

More often interacts with other threats: invasion, habitat loss and degradation, climate change, overexploitation and loss of genetic variation

Importance might be: underestimated and increasing