challenge 5 - water, biodiversity and health

Question 1

what is the term for living without water and what are some organisms that live this way?

Answer 1

Anhydrobosis
> chironomid
> wood frogs - 65% of body water freezes
> tardigrade

Question 2

what are the physical properties of water (liquid phase)?

Answer 2

> three phases: solid, liquid, gas
cohesion: each molecule attracts its neighbour
adhesion: polarity of water molecules attracts them to other polar substances
surface tension: resistance to penetration by a liquid. water drops form because of surface tension, which causes the water to take a shape that minimises its surface area.
moderates temperature on large and small scales
high specific heat, meaning it takes a lot of energy to change its temperature

Question 3

what are the important properties of ice?

Answer 3

>provides a critical habitat
> little ecosystems
> polar bear habitat
> animals live in a solid state (frozen)
> cryopreservation - frogs

Question 4

what are the important properties of water vapour?

Answer 4

evaporative cooling: liquid to gas

> water transport system

Question 5

how is the ocean important for temperature?

Answer 5

> the oceans moderate the Earth’s temperature
coastal regions experience less extremes in temperature than inland regions
oceans water’s resistance to temperature change moderates temperature on a global scale.
oceans contain so much water that their heat capacity effectively limits the dramatic swings in global temperature that would otherwise occur.

Question 6

what are the chemical properties of water?

Answer 6

> universal solvent
> highly reactive
> solute particles irrespective of chemical nature impart a set of physical properties in solution.
  - pH -  acid/alkaline
  - NaCl - salinity
  - oxygen saturation - critical gases

Question 7

what s the distribution of water on Earth?

Answer 7

> 97% oceans (saline water)
3% freshwater
- most locked up in ice or in groundwater
- 0.3% of this water occurs in swamps/rivers/lakes
so only about 0.0072% of Earth’s water is easily accessible freshwater.

Question 8

what is water a major determinant of?

Answer 8

>life
> biomes
> ecosystems
> species assemblages
> distribution and abundance
> climate ( precipitation, temperature, sunlight, wind)

Question 9

what is a biome?

Answer 9

> major life zones characterised by vegetation type (terrestrial biome) or physical biome (aquatic biome)

Question 10

what are terrestrial biomes?

Answer 10

> distributed primarily as a function of climate and geography
consist of distinctive plants and animals with traits adapted to abiotic conditions
temperature and precipitation are two main factors that determine biomes
strongly influenced by rainfall.

Question 11

what is the water situation like in central Australia?

Answer 11

> rainfall variable and unpredictable
strong seasonality - dry winters
long periods without rain
episodic, infrequent rainfall events (no annual cycle) - but also floods and short-lived rivers
episodic rainfall events often the “drivers”
rainfall redistributed by topography
strongly dictates how life has evolved and survives in his environment
arid zones - thorny devil, kangaroo, frogs

Question 12

what are aquatic biomes?

Answer 12

> diverse and dynamic systems that cover most of Earth
> aquatic biomes account for the largest part of the biosphere in terms of area- 75%
  -oceans
  -estuaries
  -intertidal zones
  - lakes
  -rivers
  -wetlands

Question 13

how do you distinguish between aquatic biomes?

Answer 13

> distinguished by difference in chemical and physical properties
chemical factors include:
- salinity levels
- Nutrients (especially N and P)
- pH
physical factors include:
- light levels/depth
- water movement (waves, river flow, stagnant)
- temperature
many aquatic biomes are stratified into zones or layers defined by light penetration, temperature and depth.

Question 14

how are lakes divided when classifying them?

Answer 14

into several zones based on depth (light) and temperature

Question 15

describe aquatic biomes - wetlands

Answer 15

> habitats that are inundated by water at least some of the time and that supports plants adapted to water-saturated soil.
have high organic production and decomposition and have low dissolved oxygen
often develop in shallow basins, along flooded river banks, or on the coasts of large lakes and seas.
wetlands are among the most productive biomes on Earth
they slow down the movement of water
have a major role in water purification and reducing flooding
however, humans have destroyed up to 90% of wetlands
most threatened biome.

Question 16

what are the global threatening factors to freshwater?

Answer 16

> climate change
pollution (heavy metals, organic compounds, acidification)
salinisation
agriculture (irrigation, run-off, pesticides, fertiliser/nutrients)
eutrophication - enriched with nutrients
mining
thermal impacts
invasive species and disease
urbanisation - and resulting habitat loss.
HUMAN ACTIVITY IS DRIVING ALL OF THIS

Question 17

how does climate change impact on water resources in Australia?

Answer 17

> with increasing temperatures, it is important for water going from a liquid phase to a gaseous phase, i.e., more gaseous if temperature increases.
also lowers the average rainfall in Australia.

Question 18

define water security

Answer 18

“the reliable availability, sustainable use and protection of an acceptable quantity and quality of water for human health and production”

> agriculture and aquiculture

Question 19

what are the threats to water security?

Answer 19

> watershed disturbances
pollutants
water resource development
biotic threats

Question 20

what is wrong with the definition of water security?

Answer 20

fails to recognise the maintenance of biodiversity and its role in ensuring water security.

Question 21

what is a better definition of water security?

Answer 21

” sustainable access to adequate quantities of water of acceptable quality to ensure human and ecosystem health”

Question 22

what is the challenge with water security?

Answer 22

the challenge is reducing biodiversity threat, while maintaining water security
> dependent on securing water quantity and quality

Question 23

why are freshwater ecosystems important?

Answer 23

> water security is dependent upon maintenance of biodiversity
water quality - freshwater biodiversity plays a vital role in:
- nutrient uptake/cycling
- removal of chemical pollutants, heavy metal etc
- trap sediments
- mitigating pathogens
CRITICAL ecosystem function of water purification

Question 24

list the processes in the movement and cycling of water

Answer 24

>evaporation ---------  evapotranspiration
> transpiration -------- 
> condensation 
> precipitation
> infiltration, percolation and flow
> storage

Question 25

what are the different types of wetlands?

Answer 25

> swamps and marshes
> billabongs, lakes, lagoons
> salt-marshes, mangroves and mudflats
> bogs, fens and peatland
> springs

Question 26

how do wetlands purify water?

Answer 26

> soils, clays, micro-organisms, plants and animals all play a role
micro-organisms - bacteria, protists etc
- breakdown nutrients
- collate metals
- convert ammonia to nitrite and then nitrate
plants absorb nutrients like nitrates and phosphates

Question 27

what is biodiversity dependent upon in terms of water?

Answer 27

the maintenance of water security

Question 28

what is the significance of the bauxite reserves?

Answer 28

> trace elements (concentrations of ions, gases, etc) within water are often a critical determinant of the type of species present.
important determinant of species assemblages and ecosystem types.
therefore in the bauxite plateau, the water is heavily tainted by this mineral, and therefore, the species living there are highly tolerant of it.

Question 29

what can change the quality of water in a negative sense?

Answer 29

salinisation
> normally 3% salt
> freshwater becomes saline
> seawater becomes hypersaline

Question 30

what is the problem with human water-management? and how is it achieved.

Answer 30

> supply achieved through water storage.
  - dams
  - weirs
  - barrages
> these strategies can be detrimental to biodiversity.

Question 31

what are the negative effects of river damming?

Answer 31

> changes lotic (flowing water) to lentic (stationary water)
this has a range of effects including:
  -reduced flow, fragmentation of river
  - elimination of pool-riffle sequences
  - decreases water velocity
  - increases or decreases in water temperature and thermal stratification 
  - build up anoxic sediment - H2S, NH3
  - decreases oxygen levels - hypoxic or anoxic conditions
> barriers to movement
  - physical barriers
  - hydraulic barriers 
  - thermal barriers

Question 32

what is hypoxia and anoxia?

Answer 32

decreases in oxygen saturation of water
> hypoxia - low oxygen levels
> anoxia - no oxygen

Question 33

why do fish move/migrate?

Answer 33

>local movements
  - access food
  - avoid predators
  - defend territory
> long distance movements
  - migration
  - habitat selection
  - juvenile recruitment
> breeding 
  - restricts habitat use
  - interrupts spawning
  - reduces recruitment
  - population fragmentation and isolation