Lecture 9 Flashcards
Why is the coastal environment important?
Commercial Activity
Coastal development
Recreational use
Conditions and resources are needed for a healthy ecosystem.
Resources
- Nutrient availability, Oxygen/carbon dioxide, Food sources
Conditions
- Light, Temperature/Salinity structure, Exposure to air/depth range, Habitat structure
o Feeding, Predation/defence, Larval settlement, Sedimentation rate, Physical Energy (waves, currents)
What’s different about the coastal environment?
Marine organisms have evolved (or are evolving) to make best use of the resources that are available and conditions they are subjected to.
- Organisms that are subjected to a wider range of conditions (cyclic, erratic or directionally changing) have greater ranges of tolerance.
Disturbance Definition
an event, caused by physical, chemical, or biological agents, resulting in changes
Resilience Definition
the rate at which an ecosystem returns to its original state after a disturbance
Response to disturbance
1) Stress on the marine environment
2) Response of marine organisms
3) Loss of Biodiversity
4) Recolonisation depends on dispersal patterns? Adaption?
Tipping points definition
A critical threshold when a small change can have potentially drastic effects. point at where the system is post-threshold state. Gone over the hump and changes to what is natural.
What are the main terrestrially-derived fluxes to the coastal environments from humans?
Gaseous nitrogen à farming
Sewerage and industrial outfalls
Leaky septic tanks
What are good indicators of the effect of these fluxes on coastal environmental health and why?
- Increased algal growth (phytoplankton, microalgae) and seaweed
- Alteration and loss of seagrass habitats,
- Increase in extent and duration of anoxic and hypoxic water, = dead zones and ecosystem collapse
- Harmful algal blooms, = (shift in species composition of phytoplankton)..red tide cape Rodney)
- Coral reef degradation (algae outcompete coral larvae)
What is an indicator and what makes a good one?
- Easy to understand
- Adaptable –> specific to situations
- Long term
- Integrative
How do tipping points make monitoring difficult?
Why is historical data important to characterising tipping points and developing indicators?
Tricky to identify when a tipping point will occur before it does. We need to carefully monitor it and look at historical data to get an idea of what the system was like, its current state and the trend.
What are the main inputs and removals of nutrients in coastal environments?
Removal = Fishing (phytoplankton –> zooplankton –> fish)
Addition = Agriculture runoff
Generally, input>output (even with overfishing)
