Lecture 28-33 Flashcards
Land use change def
Conversion of existing natural ecosystems to other forms of landscape (generally for anthropogenic use)
What are land use changes associated with agriculture?
deforestation (lost roughly 25% of global land area) –> europe is incredibly deforested
draining or modifications to wetlands
modification of grasslands
How does deforestation impact the carbon cycle?
It impacts atmospheric CO2: trees are a major source of carbon sequestration. Carbon is required to build the persistent woody structure of trees.
Trees do not sequester carbon at the same rate throughout their lifecycle
- growth slows as the trees reach maximum height (so does carbon sequestration)
therefore, uptake of atmospheric carbon is reduced due to deforestation
- annual plants (crops) do not sequester as much carbon as trees –> lesser permeance than trees
- animal (pasture land) emit GHG through respiration
Carbon stored in wood is ultimately returned to the atmosphere through decomposition
How does deforestation impact the hydrological cycle?
Trees are a major part of the recycling of green water, even more so than other plant groups
A large tree pop. can actually impact local weather patterns through a high degree of transpiration and cloud-seeding secondary chemicals
Influence cloud cover
Explain the flying river
Density of plant life in the Amazon rainforest impacts weather patterns
Aerial river: system which brings moisture over large areas as a result of wind currents and significant plant transpiration. Water evaporated from the tropical atlantic ocean is brought by winds–produces rain but the air is recharged by recycled forest moisture. After reaching the mountains, moisture condenses and produces precipitation along the Andes. The rest of the moisture produces rainfall in Southeastern South America.
Enough trees must exist to keep the river flowing. Failure of the flying river will likely cause the reduction in rainfall in many places –> tipping point to greater forest loss in the Amazon.
What are the impacts of deforestation on nutrient cycles?
High rates of precipitation in tropical forests: soil nutrients released through burning quickly lost in soil
Area burned becomes unproductive quickly: needs burning of new virgin forest for continued harvest
Slash-and-burn agriculture
Farming technique involving the removal of woodland through the use of fire, and the farming of that land using the nutrient-rich ash as fertilizer
most common in areas with poor soil fertility (tropical areas), low GDP, and high rates of poverty (primary method for deforestation in the Amazon)
What are the impacts of deforestation on radiation budget?
Canopy cover is dark in colour –> has low albedo
Cropland and pasture actually better for albedo than tree cover –> reflect more solar radiation
What are the impacts of deforestation on biodiversity?
Forests harbor the highest levels of biodiversity for terrestrial species
Land use change leading to habitat loss of degradation –> most significant cause of species extinction risk
Land use change and biodiversity are not equally distributed globally
What is the impact of agriculture on grassland?
temperature grasslands are the most endangered biome on most continents
grasslands biome seized for cropland and pasture
- much less effort required to convert to agriculture than forest or wetlands
pasture is not equivalent to native grasslands
- completely different species assemblages
- many more native species in grasslands
- biodiversity loss
What is the role of grasslands in the carbon cycle?
grasslands may be a more reliable form of carbon sequestration than forests under a regime of increased forest fire frequency under climate change
grasslands store more carbon in soils than in aboveground biomass (roots and soils survive forest fires)
What are the impacts of agriculture on wetlands?
50% of global wetlands have been drained for agriculture production
Existing wetlands can be modified for rice production
- Dramatic loss of biodiversity in modern rice cultivation
Modification of existing water systems for irrigation
- Change in sedimentation rates can result in loss of landmass
What are the consequences of wetland loss?
1) Conversation of a green and blue water reservoir to a system which holds much less water, for a shorter period of time
- Loss of water to runoff, or rapid turnover through transpiration
2) Change in GHG cycles:
- Artificual fertilizer increasing production of nitrous oxide
- Changes in production of methane of CO2
3) Soil degradation
- Loss of soil organic matter
4) Loss in biodiversity
- Most wetland species are olbigate to that type of ecosystem (cannot live outside of a wetland)
5) Ecosystem services such as water filtration and flood prevention
What is urban expansion?
Agriculture is usually situated near human habitation
As cities grow, expand outwards and growth eventually overtakes. Agricultural land is converted to urban space
How does urban expansion impact environmental systems?
Changes local radiation budget
Changes local hydrological cycles
Changes carbon cycle
Changes nutrient cycle
Biodiversity loss
How does urban expansion change radiation budget?
most man-made surfaces have a low albedo
urban heat island: increased temperature resulting from heat radiating from low albedo man-made structures
How does urban expansion change the hydrological cycle?
Covering land surfaces with non-porous coatings (asphalt) contributes to uncaptured runoff and slows/prevents groundwater infiltration
Surface mining consequences
dramatically alters landscapes: removal of forest, wetlands or grasslands
alter morpology of the landscape
Mountaintop removal mining consequences
removal of all biomass and mass modification of the geology of a region
permanently alters the topography of a landscape –> changes how water and sediments move through the environment
Impacts of surface and sub-surface mining
Chemical contamination of the lanscapes
Some mined substances need processing before market or require chemicals for extraction
- Chemicals used in these processes often highly toxic
- Long history of improper storage of these chemicals in the mining industry
Reforestation
Potential to remove 25% existing atmospheric carbon
Effort goals:
- reduce soil erosion and occurrence of sandstorms
- significant contributor to meeting GHG reduction goals
- recreate a local timber industry
- support local biodiversity (many species dependent on tree cover for survival)
- cultural pride
Reforestation in Iceland
Rapid and extensive desertification (land degradation in arid, semi-arid, and dry sub-humid areas) resulted in Iceland
- Land degradation where biological productivity of soil is lost
High winds
- stripped soil and produced deadly sandstorms
What are some challenges with reforestation?
Remaining soil is of very poor quality (little organic matter)
Lack of other plants to help support tree growth
- Herbaceous species improve local moisture through transpiration
- Support microbial communities essential for healthy plant growth
Short growing season
- Carbon sequestration is related to growth rate
- Short season = slow growth
Feral sheep are common
- Most trees planted are seedlings, easy food for sheep
Replanting trees does not replicate natural species’ richness
- Does not replace dependent species
- Some will return, but some do not naturally reoccur after deforestation
Ecosystem services
Outputs, conditions, processes of natural systems that either directly or indirectly benefit humans
- Benefits can be essential or simply helpful
- Benefits can be material or social
Involved aspects of hydrology, biogeochemistry, ecology, and economics
Briefly recount the timeline of the ecosystem theory
Pre 1970s: we are self-sufficient as a species (domination of nature, can solve any shortcoming through technology)
1970s: ecosystem service concept popularized as a conservation framework –> protect the environment movement
1990s: ecosystems provide a service that can be quantified and valued monetarily
2003: Millennium ecosystem assessment project funded by UN
What is the Millennium Ecosystem Assessment?
Ecosystem services can be categorized into 4 main types:
1) provisioning services
2) regulating services
3) cultural services
4) supporting services
Provisioning services
goods/products derived from ecosystems
examples:
- food resources (plants, animals, fish)
- freshwater
- raw materials (wood, fibers, oils)
- energy (biofuels)
- pharmaceutical resources (traditional medicines and sources of new pharmaceuticals)
Regulating services
The benefits obtained from the regulation of moderation of natural processes
Examples:
- moderation of extreme events
- air and water purification
- climate regulation
- carbon storage
- decomposition
- prevention of soil erosion
- pollination
What is an example of moderation of extreme events (regulating services)?
Mangroves reduce damage from floods, hurricans, droughts.
They protect shorelines from exreme wave events, and also provide additional ecosystem services, for example in the form of products (fish)
How is air purification a regulating service?
Plants purify air through several different mechanisms
- CO2 removal through photosynthesis
- Removal of particulate matter that is dangerous for humans (plant leaves are covered in wax or hairs that particulate matter sticks to. When it rains, it bring the particulate matter to the soil where is it less likely to go back into the atmosphere)
- Nitrogen fixation in leaves –> mediated by symbiotic bacteria
How is water purification a regulating service?
Waste-water treatment: specific components of aquatic communities are excellent at removing and purifying elements of water contamination
Wetland plants naturally remove excess nitrogen and phosphorus from agricultural fertilizer runoff
Uptake contain heavy metals from soils (can then be removed, taking the heavy metals with them)
Mussels (and other bivalves):
- filter feeders
- will concentrate pollutants as they consume phytoplankton (microplastics, pesticides)
What are constructed wetlands?
Artificial wetlands designed to maximize the water filtration potential of a wetland ecosystem
How is erosion prevention a regulating service?
erosion prevention and maintenance of soil fertility: soil erosion is a key factor in the process of land degradation and desertification
What role do decomposers have in regulating services?
Major role in the carbon cycle and supporting heterotrophs and photosynthesizes
- complex organic molecules reduced to atmopsheric CO2 or different simpler carbon molecules
Release of minerals and elements into the environment for further use by life
Role in suppressing disease transmision in communities (example vultures only eat dead matter –> important scavenger and effective rapid decomposers)
How is pollination a regulating service?
Estimated 35% of crops directly dependent on pollination for production of harvestable product
- 33% of all plant species require a pollinator for seed production
- loss of pollinators would see seed production reduced by 80% in half of all flowering plant species
Cultural services
include non-material benefits that people obtain from ecosystems such as spiritual enrichment, intellectual development, recreation and aesthetic values
Example:
- River in New Zealand given legal personhood under law
- India gave the Ganges and Yamuna River status as lining humans under the law
Supporting services
ecosystem services internal to ecosystems, maintaining ecosystem integrity, funcitoning, and resilience and the capacity of ecosystems to produce provisioning, regulatory and cultural services
examples:
- photosynthesis
- nutrient cycling
- water cycle
- soil formation
- genetic resources
- habitat
Allelic diversity
the variety of alleles between and within populations of species
provides genetic resources for
- improving commercial crops and livestock
- adaptation to environmental stressors (wild and domestic species)
How are genetic resources a supporting service?
Species are not uniformly genetically identical across their range
Local adaptation fueled by environment and local genetic mutation
- Create substantial allelic diversity across the range of a species
Genetic adaptations within an isolated sub-population may be useful for adapting to climate change
Example: genetic engineering program that produced american chestnut trees which are highly resistant to fungal disease
Genetic resources with the chestnut tree
Single-gene insertion (a wheat gene)
Produces a single enzyme
Destroys a compound in the pathogen called oxalate
- pathogen uses oxalate to initiate the infection
Without oxalate, pathogen cannot infect a chestnut
- Effectively making the trees immune
Release of teh transformed American chestnut would be a major paradigm shift for conservation
- The first genetically modified organism which has been created to replace a non-transformed native species
Economic valuation of ecosystem services
major application of the ecosystem services concept in the 21st century
- assigning an economic valuation in order to value the loss of these services
How much is someone willing to pay to have a service or to pay to not be without a service (WTP and WTA)
Valuation likely to differ at the local scale
Benefits of ecosystem services may not be direct (externalities)
Externalities definition
cost of benefit received by a third party who had no control over how the cost of benefit was created
The Economics of Ecosystems and Biodiversity (TEEB)
Study attempting to quantify economic valuation of global biodiversity
Amazon Fund
21$ billion fund support alternative economic development in Brazil, halt deforestation
Norway –> 1$ US billion
Germany, USA, UK –> pledged 5$ US billion by 2020
What are the primary drivers of biodiversity loss
habitat loss
invasive species
overexploitation
pollution
climate change associated with global warming
influencers: humans pop. growth, increasing consumption, reduced resource efficiency
Contaminant def
presence of, or elevated concentrations of, a potentially toxic substance in the environment
Pollution def
contamination that results in measurable effects on natural processes (abiotic or biotic)
Primary pollutant def
pollution that is produced directly from a source
Secondary pollution def
primary pollutants undergoing chemical changes within a natural reservoir, forming a different form of pollutant
Bioaccumulation def
toxin levels increasing in the body tissues of an individual during its lifetime
limited to the lifetime of an individual
biomagnification def
toxin levels concentrating in higher trophic levels
species of higher trophic levels –> higher concentrations of these pollutants
What are some natural sources of pollution?
Volcanoes releasing large qties of gaseous pollutants
Fossil fuels leaking into natural bodies of water (petroleum seep)
What are the 4 main groupings of pollution?
Land pollution
Air pollution
Water pollution
Energy pollution
Land pollution
Deterioration of land surfaces (above or below ground) as a result of contamination
Common examples:
- Landfill
- Soil contamination
- Pesticides and herbicides
Often the source of contaminants which enters water or air reservoirs
Litter/landfill
disposal area for solid waste
landraising: piling solid waste on the surface
landfilling: digging a hole for the burying of solid waste
What are modern landfills?
Multiple layers of protection to contain solid waste and leachates within the landfill
Sealed with impermeable layer –> low impact on environment
- risk of seal breaking and leaking
Designed to be buried once filled and converted to greenspace
These produce methane (because sealing it prevents access to oxygen)
Soil contamination
Any substance present in a soil which is potentially harmful to human health
- both manmade substances and exceedingly high levels of natural substances
examples:
- heavy metals
- pesticides and herbicides
What is the risk with urban horticulture?
Urban soils are often heavily contaminated after successive generations of urbanization
Plants take up heavy metals in soils and incorporate into tissues
Urban horticulture may be exposing populations to heavy metals from contaminated metals
Pesticides DDT
DDT was the first known pesticide that could effectively kill a wide number of different insect species
Widely heralded as a miracle compound (relatively non-toxic to humans)
Applied very liberally
DTT can both bioaccumulate and biomagnify
- entered food chains through water and soil contamination
Banned 1970-1980s
DDT in birds
High levels of DDT interfered with calcium metabolism
Female birds contamined with high levels of DDT produced eggs with eggshells too thin to incubate
- The female would crush the egg shell during incubation
Resulted in significant declines in several bird species
Water pollution
pollution of blue water resources
Example:
- human sewage
- PCBs
- Mercury
- heavy metals
- fertilizers
- oil spills
- pharmaceuticals
Mercury
Cycles through atmosphere, water and soils
Natural sources –> volcanoes, fires, chemical weathering
Anthropogenic activities –> coal burning, mining, waste incineration
Mercury causes the greatest rates of harm once it enters water systems
What are the impacts of mercury in water systems?
Climate change and overharvesting may have a positive feedback on mercury biomagnification and bioaccumulation
What are the impacts of mercury in water systems?
Climate change and overharvesting may have a positive feedback on mercury biomagnification and bioaccumulation
Phosphorous runoff
Phosphorous (P) is a major limiting nutrient in plant and algae growth
P is incorporated into fertilizer in modern agriculture –> plants to not absord all P in fertilizer
Excessive runoff of P enters waterways, and results in eutrophication
Eutrophication
Excessive P in waterways causes an algae bloom
As algae die, large increase in decomposition by bacteria
Decomposition requires oxygen –> removes large amounts of oxygen from water
Fish die from lack of dissolved oxygen in water
Pharmaceuticals
Medicines and artificual hormones for human and animal use
Can be directly released during production
Can pass through the body and be excreted in urine
Some pharmaceuticals enter water systems
Can enter food chains or have direct impact on wildlife
Can be reintroduced back into drinking water
Many older water treatment systems are not designed to remove pharmaceuticals
Effects:
- Increasing prevalence of antibiotic resistant bacteria
- Inducing sex change in fish
Air pollution
pollutants suspended in, or derived from, the atmosphere
Examples:
- GHG
- smog (particulates)
- heavy metals (lead)
- acid rain
Lead
mainly locked in geological sources
Anthropogenic lead is released into the air during coal combustion, manufacturing, incinerators, jet fuel
What happens when lead bioaccumulates?
Brain damage
Lower IQ
- can affect babies in utero
- greater effects in children with developing nervous systems
Can become stored in bones and release years after inital exposure
Acid Rain
sulfur dioxide (SO2) and nitrogen oxides (NOx) in the atmosphere react with atmospheric molecules (H2O, O2) to form sulfuric and nitric acids
- nitrogen oxides –> agriculture
- sulfur dioxides –> industry
Acids mix with precipitation, fog, snow
- Acid rain (fog and snow)
pH of typical rain –> 5.6
pH of acid rain –> 4
Impacts of acid rain
Directly affects pH of soils and freshwater ecosystems
In soils, it removes important plant nutrients through chemical reactions
In freshwater ecosystems, mortality of species throughout trophic levels, juvenile forms of species generally more vulnerable
Energy pollution
pollution resulting from the transfer or production of energy in systems
noise, light, thermal energy
Thermal pollution
anthropogenic change of temperature in systems
can occur in heavily managed water systems and near powerplants that require water as coolant
- releasing water from reservoir is going to be colder than the stream (since depth of reservoir is more significant than the stream –> more cold)
Noise pollution
excessive noise contaminating systems
all cetaceans communicate by sound
- shipping and other marine activities impair this
increases stress, limiting ranges, suspected cause of mass stranding
Light pollution
contamination of environment with excessive artificial light (generally at night)
dangerous for birds, baby turtles
dark-sky reserve: conservation area defined by absence of artificial light during night
epidemic vs. pandemic
epidemic: affecting large number in region
pandemic: spread over several countries
What are the 4 types of agents?
Viral
Bacterial
Parasitic
Fungal
Explain the epidemiological triad
Host: organism harboring the disease
Vector: organism that carries and transmits the infectious pathogen to host
Agent: the microbe that causes disease
Environment: the external factors that allow transmission
What was the effect of Peacock Cichlid ocellaris on the food web of Lake Gatun in Panama?
The Cichlid fish ae all the fish that ate insects. As a result, there was an increase in insects. It caused the collapse of the fish populations that kepy mosquitos in control.
An increase in mosquitos lead to an increase in malaria cases.
What is a non-native species?
A species introduced to a region outside of its natural historical range (where it evolved)
What is a biological invasion?
It is the spread and establishment (I.e. forms a self-sustaining population) of a species into a region beyond its natural range (where is evolved).
Explain the process of a biological invasion
Introduction –> (formation of a self-sustaining population)
Establishment –> impacts often detected here
Geographic spread (gets hard to eradicate the more it spreads out)
Natural of human-assisted dispersal
What is an invasive species?
A species undergoing a population outbreak that causes adverse ecological or economic effects
An introduced (alien) species that spreads rapidly (i.e. a highly successful invader
How are humans playing a part in biological invasions?
Species are being moved long distances to regions that they could never reach without human assistance
The Great Ameican Biotic Exchange
3 million years ago: North and South America became connected by the Panama land bridge
Mammal moved north and south
A series of extinctions followed on both continents
North America mainly dominated
The Great Ameican Biotic Exchange
3 million years ago: North and South America became connected by the Panama land bridge
Mammal moved north and south
A series of extinctions followed on both continents
North America mainly dominated
What is peculiar about the rates of biological invasions in the present?
Invasions are now occurring at unprecedented rates
How are modern (human-facilitated) invasions occurring?
Accidental introductions
- Hitchhikers (ballast water, brown tree snake)
- Escapees (asian carp)
Deliberate introductions
- Biological control (mongoose)
- Live trade (food - nile perch, ornamental - kudzu, pet release - goldfish)
How is ballast water contributing to biological invasions?
3-10 billion tonnes of ballast water moved annually
1 liter contains hundreds of zooplankton, thousants of phytoplankton, millions of bacteria and billions of virus particles
7,000 species are carried in ships at any given time
Water is release in different waters –> species are introduced to the ecosystem
Example: zebra mussels
How did the brown tree snake become an invasive species?
Austraia, Indonesia –> Guam
Through military aircraft (hitchhikers)
caused 16 extinctions (birds, lizards, bats)
Danger to humans: snakebites, power outages
Economic impacts: $10 billions US from 1986-2020
How did the asian carp become an invasive species? What are its impacts?
from Asia –> used in aquaculture facilities throughout US. It was introduced to fixed areas to eat phytoplankton we did not want
Imported in 1970s, escaped shortly after
It escaped during a flooding established in Mississipi River
Example of a escapee
Outcompete native fishes (food and space)
Consume 20-40% of its body weight
How did the mongoose become an invasive species? What are its impacts?
From asia –> Mauritius, Fiji, West Indies and Hawaii in the late 1800s
It was introduced to control rats in sugar cane fields
Example of deliberate introductions (biocontrol)
Declines and extirpation of native mammals, birds, reptiles, amphibians (eat anything)
How did the nile perch become an invasive species? What are its impacts?
From most of africa –> Lake Victoria, Africa in 1954
It was introduced to counteract drastic drop in native fish stocks (overfishing)
Example of deliberate introductions (live trade - food)
Caused 200+ spp extinctions (endmeic cichlids)
Led to deforestation (drying it out requires more wood –> deforestation –> soil erosion)
Soil erosion leads to eutrophication
Displacement of people
How did goldfish become an invasive species? What are its impacts?
From asia –> now in most natural water bodies
Example of deliberate introduction (Live trade -Pet release)
Competitor and predator of native fish
Stir up mud by sucking up rocks and spitting them out, which increases cloudiness (affects plant growth)
How did kudzu become an invasive species? What are its impacts?
From asia –> introduced to the US in 1876 for the centennial exposition in Philadelphia
Introduced for ornamental reasons, also for erosion control
Example of deliberate introduction (live trade - ornamental)
Smother other plants
Outcompetes for light
Doubles emissions of nitric oxide
How did starlings become an invasive species? What are its impacts?
From Europe –> Central Park NY
March 6, 1890
A single person introduced every bird mentioned in Shakespeare’s plays to America
Release 60 starlings - today more than 200 million from Alaska to Mexico
$800 million annually in crop damage
Disease spread
Eat a lot of seeds –> destroys crops
Plane crash
What are differences between natural (prehistoric) and human-assisted invasions?
Natural invasions:
- low frequency of long-distance dispersal events
- small number of species transported per event (except during biotic interchange)
- small variation in mechanisms and routes of dispersal
- Rare to have invasions between biogeographic realms
- Low potential for synergies with other stressors
Human-assisted invasions:
- very high frequency of long-distance dispersal events
- potentially large number of species transported per event (except during biotic interchange)
- extremely large variation in mechanisms and routes of dispersal
- Common to have invasions between biogeographic realms
- Very high potential for synergies with other stressors
Why are biological invasions bad for native biodiversity?
They are a major threat since non-native consumers cause more damange to prey popultions than do native consumers
What are the impacts of zebra and quagga mussels?
Benthification (resources being sucked out)
Increased concentration of ammonia, nitrates, phosphates
60 native unionid mussles threatened with extinction (suffocate native mussels)
$300-$500 million annually in damages to power plants and water systems in the Great Lakes region
What are some common traits of invasive species?
Not a picky eater (eat a lot of things)
High tolerance for different environmental conditions
Phenotypes variations
What are some common traits of invaded ecosystems?
Islands and lakes –> relationship between diversity and size
Smaller area –> likely to run into something they have not before
What are the proportions of modern animal extinctions in which invasions were a causal factor?
Global animal extinctions: 54-62%
Global fish extinctions: 48%
Global mammal extinctions: 48-69%
Global bird extinctions: 50-60%
Global reptile extinctions: 57%
Are the impacts of invasions predictable?
No, invasions can disrupt ecosystems in unpredictable ways
What was the effect of opossum shrimp on Kakonee Salmon in Flathead lake?
Introduced hoping to increase salmon populations for fishing
Salmon are a focal species, and eat zooplankton and opossum shrimp. Shrimp eat zooplankton
However, salmon and shrimp are active at different times
- Salmon eat during the day, dive deep at night
- Shrimp feed on zooplankton at night.
As a result, the shrimp were eating the salmon’s food source
Lake trouth increased since it eats the shrimp –> increasing salmon predation
Are biological invasions easy or difficult to manage?
Invasive species are hard to eradicate
List an example of successful eradications of an invasive species
Zebra mussles in Lake Waco and Lake Winnipeg using potassium chloride
Mongoose eradicated from 6 islands using traps and poison
Goldfish eradicated in West Medical Lake, cost $150,000 to remove
How is decreasing arctic sea cover predicted to impact future invasions?
New invasion pathway for species and organisms to cross
What should be done to avoid future biological invasions?
1) Create systems of early detection and rapid response at national and international scales
2) Develop better risk assessment methods for identifying and prioritizing high-risk invaders
3) Identify and control emerging vectors and pathways
4) Tighten regulations concerning trade in live organisms
Zoonoses (zoonotics)
diseases and infectinos of vertebrate animals that can be transmitted to humans
What are the types of zoonotic diseases
Emerging:
- newly appear in humans (or now rapidly increasing in incidence or range
- example: ebola, HIV/AIDS, COVID19
Endemic:
- Occur intermittently
- Triggered by events
- example: anthrax, leishmaniasis, rift valley fever
What are some transmission routes of zoonotic diseases?
Aerosol: occurs when droplets are passed through the air from an infected animal and are breathed in by a person
Oral: occurs by ingesting food or water contaminated with a pathogen.
Direct contact: requires the presence of a pathogen in the environment or within an infected animal A person becomes exposed when the pathogen directly touches open wounds, mucous membranes or the skin
Fomie: a formite is an inanimate (non-living) object that can carry a pathogen from an animal to a person. (surfaces)
Vector: occurs when a an insect acquires a pathogen from one animal and transmits it to a person
Give some examples of when zoonoses became human disease outbreaks
1) Epidemics of European diseases in the Americas. Shortly after the arrival of Europeans in the sixteenth century were responsivle for the deaths of up to 95% of the indigenous popultions (diversity of domestication in Old World)
2) Tuberculosis outbreak of nineteeth century. Associated with industrialization in Western Europe and over-crowding; killed 1/4 pop.
3) Zoonotic sleeping sickness in 1910s. Associated with expansion of colonial rule in Africa. Killed 1/3 in Uganda and 1/5 in Congo River Basin.
4) Influenza pandemic of 1918. In the last months of WW1, and following years (1918-1921). Killed 50 million people
What is zoonotic spillover?
Transmission of pathogens from wild animals to humans
Why are bats common disease transmitters?
Bats are very diverse. A lot of species with huge populations.
They fly, and have adaptations for flight
They also do not have symptoms from most diseases
Why are the rates of zoonotic spillover increasing?
1) Increasing demand for animal protein
2) Unsustainable agricultural intensification
3) Increased use and exploitation of wildlife
4) Unsustainable utilization of natural resources accelerated by urbanization, land use change, extractive industries
5) Travel and transportation
6) Changes in food supply chains
7) Climate change
How is increasing demand for animal protein driving zoonotic disease emergence?
Produce 3x more meat we did 50 years ago
Southeast Asia, Sub-Saharan Africa: rapid increase
Per capita increase in animal consuption + pop. growth
Pigmeat is the most popular meat globally, but production of poultry increasing most rapidly
How is unsustainable agricultural intensification driving zoonotic disease emergence?
Increased demand –> intensification and industrialization of animal prodution
Genetically similar animals (more vulnerable to infection) example: factory famring promoted swine flu
Close proximity, poor conditions
Since 1940, agricultural intensidication associated with >50% of all zoonotic infectious diseases in humans
How is increased use and exploitation of wildlife driving zoonotic disease emergence?
Bushmeat: harvesting wild animals as source of protein
Recreational hunting, decorative, medicinal, commercial products
New roads in remote areas –> increased access
How is unsustainable utilization of natural resources accelerated by urbanization, land use change, extractive industries driving zoonotic disease emergence?
Rapid urbanization leads to novel contacts with wildlife, livestock, and ppl
- Irrigation systems encourage vector-borne zoonoses
- Deforestation and fragmentation
- Ecological tourism
- Encroachment into wildlife habitats
Deforestation leads to increased infectious diseases
Give an example of deforestation leading to increased infectious diseases
Malaria in Amazon
- 10% increase in deforestation leads to 3.3% increase in malaria incidence
Increased biting rate, available breeding habitat for primary vector, increased survival
- a lot of fruit bats
- killed habitats so move into the village
- bats like fruit, so they take sips –> transfer of bodily fluids that ppl would then drink
- get diseases from pigs eating the fruits that bats ate
How is travel and transportation driving zoonotic disease emergence?
Diseases can move around world faster than incubation periods
Increasing human travel and trade
How are changes in food supply chains driving zoonotic disease emergence?
Increased opportunities for cross-contamination
Difficult to trace
Rapidly expanding and poorly managed wet markets
Food chain length is increasing
Passing through more countries increases the chances of it getting infected
How is climate change driving zoonotic disease emergence?
Zoonoses are climate sensitive and will thrive in warmer wetter climates
Heavy rainfalls increase mosquitoe breeding sites
High water temp –> larvae develop rapidly
Biting rate increases with temp. and humidity
By 2085, estimated that about 50-60% of the projected global pop. would be at risk of dengue transmissions
Warm, wet winters and springs led to expanding pop. of rodents to move indoors in search of water/food, increases human-rodent interactions
Influenza types
Influenza A: infects a wide range of animals including birds
Influenza B: mainly infects humans
Influenza C: infects humans and pigs but more rare than type A and B
Influenza D: infects cattle
How did influenza evolve?
The outer membrane of a flue virus covered with enzymes H (hemagglutinin) and N (neuraminidase)
These help the virus attack to, and break into and out of host cells
There are diff types of H and N, and fidd viruses have diff. combinations of these types
H and N (antigens) trigger immune responses (antiboies) by the host
A person’s immunity to these antigens reduces the probability of infection and the severity of disease
A person’s immunity to one H-N combination confers little or no protectino against a diff combination
Therefore, mutations in viruses can create strains that infect large numbers of people
What are the two ways in which influenza viruses evolve?
Antigenic drift: point mutations cause small changes in the surface antigens (H and N)
- These can lead to regional epidemics in populations that have had no previous exposure
- Small changes to antigens and spike proteins make it so that some antibodies to not recognize (local outbreaks)
Antigenic shift (Genetic reassortment): the process by which the whole H-N combination changes
- Large pieces of genome are exchanged between different viruses attacking the same cell
- Produces novel flu strains distinct from all previous strains –> potentially causing a pandemic
How did influenza show up and mix?
Bird virus –> pigs = mixing vessels –> reassorted virus –> human virus
= humans become mixing vessels
Zoonotic coronaviruses
named corona for the crown-like arrangement of spike-shaped proteins on surface
Some cause mild upper respiratory illness (common cold)
SARS-CoV-2
enveloped virus
spike (S) protein allow virus to bring and enter host cells
As with SARS-CoV, S protein brings with ACE-2 receptors on human cells (concentrated in upper and lower airways of lungs)
RNA is 30,000 letters long (one of the largest RNA viruses)
High mutatino rate + proofreading (reduces negative mutations)
How did SARS-CoV-2 arrive in Wuhan?
First detected in December 2019 in Wuhan (present in Hubei province for about a month prior)
15 000 km from closest known sarbercovirus (in horseshoe bats in Yunnan province)
First deteced cases associated with Huanan wet market in Wuhan
Not certain of animal source, but live civets, foxes, minks, and raccoon dogs, all susceptible to sarbercoviruses were for sale
Farmed for their fur at large scale and then sold to animal markets or were sold alive for food
How was SARS-CoV-2 transmitted to humans?
Recent evidence: 2 separate zoonotic transmissions
Bats –> intermediate host (wild animals and domestic animals) –> humans (two seperate species that passed it on to humans)
How did pork shortages contribute to the emergence of SARS-CoV-2?
Shortage of pork products in China in 2019
African swine fever virus pandemic, led to 150 million pigs culled in China (slaughtered to prevent pigs from passing on the disease)
Pork prices reached record high in November 2019
Food consumers and producers resorted to alternative meats, including farmed and captured wildlife
How can we manage and prevent future zoonotic outbreaks?
Raise awareness and understanding of zoonoses
Increase investments in interdisciplinary approaches
Expand scientific enquiry into social, economic, ecological dimensions of emerging diseases
Improve cost-benefit analyses of emerging diseases
Develop effective means of monitoring and regulating practices
Include health considerations in incentives for sustainble food systems
Identify key drivers of EID in animal husbandry
Support intergrated managed of landscapes that enhance sustainable co-existence of agriculture and wildlife
How does the extinction vortex work?
5 threat to biodiversity (land use change, overharvesting, pollution, invasive species, climate change, disease)
–>
Small, fragmented, osilated populations
–>
demographic instability and inbreeding
–>
Population decline
–>
extirpation or extinction
Additive model
the combined effect of two or more stressor is additive when equaliting the sum of the individual effects
stressor 1 (-) + stressor 2 (-) = ecosystem (–)
Non-additive model
1) Antogonistic: the combined effect is less than the expected additive effect
stressor 1 (-) –> stressor 2 (-)
stressor 1 (-) and stressor 2 (-) –> ecosystem (–)
2) Synergistic: greater than the expected additive effect
stressor 1 (+) <–> stressor 2 (+)
stressor 1 and stressor 2 –> ecosystem (–)
How do agrochemicals increase risk of human schisosomiasis
By supporting high densities of intermediate hosts. Predator mortality increases greatly in the presence of the pesticide
Example:
Snail-borne parasitic disease
One of the most pimportant water-based diseases of humans in developing countries
Caused by tremotodes
Snails = intermediate hosts
Humans=the definitive host
Infected when free-swimming life stages of trematodes released from snails in waters penetrate skin of definitive host and mature into adults
When you remove the top-down effect, the snail density becomes higher because they were limited by predation (predators controlled snail populations)
Bottom up effects: more algae = more snails
What type of interaction is pollution and climate change in its contribution to pest outbreaks?
additive interaction
pollution (+) + climate climage (+) + overfishing (+) –> pest outbreaks
What type of interaction is pollution, overfishing and climate change in its contribution to jellyfish blooms?
additive interaction
pollution (+) + climate climage (+) + overfishing (+) –> jellyfish blooms
How does overfising, eutrophication, climate change and habitat modification promote jellyfish blooms?
Climate change increases phytoplankton –> increases zooplankton –> increases jellyfish blooms
Eutrophication increases phytoplankton and decreases higher predators –> increasing jellyfish blooms
Overfishing decreases higher predators –> increasing jellyfish blooms
increasing jellyfish blooms decreases fish larvae –> decreases higher predators (positive feedback loop)
How does overfishing and nutrient pollution interact with temperature to disrupt coral reefs?
Removal of herbivores by overfishing, increased water temp., pollution from domestic sewage/agriculture runoff
Removing all three forces that limit the growth of algae –> overgrowth of coral by algae (unhealthy reefs)
What is an exampe of an antagonist interaction?
1) Climate change and overfishing increase neurotoxicant in marine predators
- Big fish have higher concentration of mercury, overharvesting cod reduces mercury
climate change (+) + overfishing (-) –> neurotoxicant in marine predators
2) Effects of biological invasion and environmental warming on detritus processing in freshwater ecosystems
- invasive species have an easier time breaking down leaf litter
climate change (+) –> invasive species
climate change (+) + invasive species (-) –> detritus processing
What are characteristics of synergies?
Occur when stresses overlap
Often unpredictable
Sudden disruptions or abrupt shifts
Nonlinear behaviour (e.g. feedback loops, cascading effects)
Give an example of a synergistic: land use, biological invasion, grassland persistence
Alteration of fire regimes by land clearing and grass invasion
woody vegetation –> fire –> selection for grass –> grassland (<–introduction of invasive grasses) –> (flammability/microclimate) fire
Invasive species takeover grassland (perpetuate feedback)
Self-sustaining their ideal environment
Risk of fire increases with abundance of exotic weed
Synergistic interaction: n-pollution, disease, amphibian deformities
Parasites in the food web: linking amphibian malformations and aquatic eutrophication
Sever limb abnormalities induced in Pacific treefrogs exposed to trematode parasite
Eutrophication causes shift in snail species composition toward the exclusion first intermediate hosts of parasite
Synergistic interaction: land use, climate change, bird populations
Additive effects of climate change and land-cover change on long-term population trends of North America
Synergistic interaction: invasive algae, invasive bryozoan, kelp
kelp beds are determined by the abundance of sea urchin
Japanese seaweed: forms dense meadows, competes with kelp beds, harmful to sea urchins and possibly lobsters
Bryozoan: colonial organism, forms thing mesh-like encrustation on kelp, increase tissue loss and blade breakage
If kelp is intact, codium cannot invade well
Kelp encrusted with membranipora become fragile
Breakage of kelp allows codium to displace kelp
Synergistic interaction: CO2, invasion, native oysters
Ocean acification increases the vulnerability of native oysters to predation by invasive snails. As shells get thinnger, it becomes easier for snails to drill into the oyster shells. Invasive snails were tolerant to elevated.
CO2 in surface waters –> acidification –> reduced shell thickness of prey molluscs –> vulernability to predation
The extinction vortex: amphibians
effects of land use change on amphibians
- an estimated 63% of all amphibian species affected, and as much as 87% of the threatened species affected
- require microhabitats with appripriate conditions (moisture, temperature, pH, refuges, food, easily disrupted)
- most species in rainforests (72%)
- require multiple habitats throughout life
What are the effects of overharvesting on amphibians
harvested for food, medicine, research, teaching, pet trade
hundreds of millions consumed each year in EU and USA
Effects of pollution on amphibians
Uniquely permeable skin, cannot control movement of water across external surface –> very sensitive to changes in water quality
Mercury, pesticides, herbicides, endocrine disruptors (testicular oogenesis in wild leapard frogs due to atrazine)
Effects of invasive species on amphibians
Competition for food, spaces, other resources
Direct predation on adults or larvae
Vectors and reservoirs for disease and parasites
Hybridization with native species
Effects of climate change on amphibians
Altered breeding phenology (shifting timing of breeding) led to decreased survival of larvae (snowmelt or desiccation)
Sensitive to changes in precipitation (permeable skin)
Changes to species range (to higher elevations, new species interactions)
Rising sea level –> loss of coastal wetlands
Increased UV-B radiation damages amphibian eggs
Effects of disease on amphibians
Fungal pathogen
Epidemic disease associated with numerous amphibian population declines around the world
Synergies or ecological surprises
Occur where stressors overlap
cause unexpected changes in ecosystems
Result from the connectedness of environmental systems and their components (system complexity)
Demonstrate that environmental problems cannot be solved in isolation –> we must use a system-level approach
