What is meant by runaway effects?
Self-reinforcing feedbacks could push the Earth System toward a planetary threshold that, if crossed, could prevent stabilisation of the climate even as emissions are reduced. E.g. melting of ice caps expose more ocean (lower albedo) which lead to further warming, further melting, etc. Irreversible, can change ocean currents & permanently change the climate around the world.
What are production and trophic efficiencies?
- Production “efficiency”: the % of energy
assimilated by an organism that is converted into biomass (i.e. growth). Depends on the organism, insects and reptiles are more efficient whilst mammals being endotherms consume more energy for body heat. - Trophic “efficiency”: the % of energy transferred and used by the next trophic level. Simplified estimation considered to be 10% per trophic level.
How does temperature change relate to nutrient transfer?
Biodiversity loss and changing conditions (e.g.
climate, water) will impact efficiency pathways
Increased temperature (climate)
= more energy into cellular respiration
= less available for growth
Give an example of how change to 1 species can have detrimental ecosystem effects?
Nutrient rich runoff from farms can generate algae overgrowth in water systems. The overgrowth of algae consumes oxygen and blocks sunlight from underwater plants. When the algae eventually dies, the oxygen in the water is consumed. The lack of oxygen makes it impossible for aquatic life to survive.
Give an example on ecosystem change which affects natural cycles?
Clearing forest affects the natural cycle of water evapotranspiration through the trees & recycled rainfall, resulting in less rainfall & less biomass in the area. Nutrient cycling slows as less rain means habitat supports less primary producers and decomposers have less detritus to feed on. Biodiversity decreases.
What is an organisms’ physiology?
the functions and activities of living organisms and their parts, including all physical and chemical processes
What is ecophysiology? can you give an example?
the study of how the environment, both physical and biological, interacts with the physiology of an organism. E.g. temperature affects endotherms as they need to use energy to thermoregulate and also affects the activity of ectotherms which rely on external temperature for their bodily functions & behavious.
What factors shape physiology and fitness?
- Development, regulated by: * Temperature
* Moisture * Population density * life history - Phenology: Timing of important life history events
- The organism’s fitness: (ability to survive +
ability to reproduce)
How do we measure responses in ecophysiology?
We explore:
- the limits placed on organisms by their physiology (e.g. seasonal migration)
- how organisms respond to environmental challenges (e.g. acclimation)
- how organisms have adapted to their ecological niches (e.g. specilalisation)
What is phenology?
The influence of climate on annual phenomena (timing) of animal and plant life such as reproduction and migration
How do individual responses translate to communities?
A change in one component of the network can affect many other components, e.g.
environmental change > effects phenology & bahaviour of a species > changes species interactions > extinction of some species > further shifts in distribution > changes in community structure
Liebig’s Law of the minimum is?
Growth [in plants] is determined by the scarcest resource (limiting factor): nutrients, water, light, oxygen
Why study ecophysiology?
To understand physiological thresholds in response to environmental challenges.
Discuss the implications for fitness when environmental conditions are outside the optimum range?
Fitness decreases and physiology focuses on surival, therefore can lead to non vital functions e.g. ability to reproduce narrows or stops.
Name and describe three general ways in which individual organisms can respond to environmental change?
- Stay: tolerate, evolve, moderate physiology or behaviour. E.g. acclimation, behaviour change, phenotypic plasticity
2: Go: colonise new territory
3: Die: failure to do any of the above results in extinction
Give examples of 2 invasive species in Aus and scale of the problem:
- Cane toads: large scale impact on predators which eat them and die from their poison, sucha as quolls, goannas, crocodiles, birds. having trophic cascade impacts as causing predator /prey imbalance. no effective controls available at this stage.
- Rabbits: large scale impact, 300+ native species threatened, controls include pathogens but does not lead to long-term eradication.
Describe natural invasion and human-induced invasion?
Natural colonisation = ecological succession: gradual process of species colonisation and species replacing each other.
Difference today is that it is vastly accelerated by human globalism. Seas are also warming up faster due to anthropogenic global warming, allowing marine species to expand their range towards the poles.
What are the 4 stages of invasion?
- Arrival – can be accidental (e.g. in ballast water) or deliberate (e.g. introduced for hunting or aesthetics)
- Naturalisation – establishment (lag phase). A population is considered established once it is able to successfully reproduce outside of its native range.
- Invasion – spread of invader: Individuals start to spread away from the point of introduction. We can use our knowledge of fundamental niche of a species to predict the severity of the impact of an invasive species. e.g. predicting the spread of cane toads.
- Impact – Generally, we talk about impacts on: Agriculture, Quality of (human) life, Environment & management costs.
An example to use for invasive species:
“Due to climatic warming, Asterias amurensis, a keystone boreal predatory seastar that has established extensive invasive populations in southern Australia.” This seastar is spread via ballast water in cargo ships. If found native in temperate waters of east asia, but is now established in Australia. There is a natural barrier of warm water between the sites (the larvae needs colder waters to survive), so its not a case of natural migration. There are now concerns that they will continue to spread to antarctica and extensive studies have been made to predict if/when this will occur.
An example to use for habitat loss in Australia:
Pelicans on the decline, require cast amounts of fish and therefore healthy waterways to feed & raise their chicks. “Like most water birds, they face challenges from a reduction and change in water flow regimes and loss of habitat due to competition with development of urban environments.”
An example to use for sampling/counting populations:
“researchers, conservationists and state officials has led to the use of drones and artificial intelligence to more effectively count the population of the colony [of pelicans]. Mr Carnegie regularly flies a drone over the colony, taking a series of images and videos that are sent to the University of New South Wales where they are analysed by an AI program. “
What is the Allee effect?
Apparent during lag phase of invasion. Slow population growth when the population is small. Due to:
* Difficulty finding a mate
* Species that feed cooperatively are less efficient
* Species that defend cooperatively are more vulnerable
* Less genetic diversity
What are the 4 stages of managing invasion?
- Prevent: prevent introduction/escape.
- Eradicate: remove species
- Contain: control spread
- Maintain: protect biodiversity
