1. VCE Biology Unit 2 Area of Study 01 Adaptations of Organisms
Chapter 13.2
Environmental factors and adaptations

2. 13.2 Living in water Good place to live.
O2 and CO2 and N are dissolved from atmosphere.
O2 also released from as by-product of photosynthesis and CO2 released as a by-product of respiration.
Mineral nutrients (phosphates, nitrates, chlorides, sulfates and carbonates) dissolved from land.
Run off from fertilised lands brings increased amounts of nutrients to the water.

3. 13.2 Living in water Abiotic factor – pH
pH – determined by amount of CO2 dissolved in water, which forms carbonic acid (H2CO3).
pH of inland waters 6 – 9.
Too much CO2 in water (low pH) will kill off fish
Acid water (like acid soils) deficient in mineral nutrients

4. 13.2 Living in water Abiotic factor – Temperature
Water retains heat very well. Water absorbs and releases heat with little change in temperature.
Aquatic habitats usually not affected by drastic temperature fluctuations.
Deep water lakes have temperature layering (fig 13.2, page 246). As water warms up it becomes lighter. This creates different temperature environments

5. 13.2 Living in water
Abiotic factor – Temperature

6. 13.2 Living in water Abiotic factor – Light
Water allows light to reach photosynthetic organisms.
The quality of light changes with depth (see figure 13.3 page 247)
Turbidity also affects penetration of light: the muddier the water the less light can penetrate. Few plants grow in muddy water

7. 13.2 Living in water
Abiotic factor – Light

8. 13.2 Living in water Adaptations of billabong animals
Pygmy perch (Nannoperca sp.) small native fish that lives in slow moving water
Factor affecting Pygmy perch is competition from introduced species (carp, trout, mosquito fish [Gambusia affinis holbrooki])
Waterboatmen also found in slow moving water. They have long paddle like feet to help them move across the surface of the water

9. 13.2 Living in water

10. 13.2 Living in water

11. 13.2 Living in water

12. 13.2 Living in water Adaptations of plants living in water
Hydrophyte (water loving) plants – water low levels of [O2] and light compared to air.
Aquatic vascular plants include rooted emergence plants e.g. reeds (Fig 13.6(a) p. 248), and crop plants e.g. rice.

13. 13.2 Living in water Adaptations of plants living in water continued
Water lilies have roots anchored in mud with their leaves (filled with air spaces) floating on the surface (Fig 13.6(b) p. 248).
The leaves have stomata only on the upper surface of the leaves.

14. 13.2 Living in water Adaptations of plants living in water continued
Submerged sea grasses have their roots and shoots under water (Fig 13.6(c) p. 248).
Leaves are flat with increased surface area
Few stomata
Very thin cuticle
Gases diffuse between water and plant across the entire leaf surface
Spongy tissue in leaves and stems ‘traps’ O2 from photosynthesis to be used for respiration in the roots.
Small amount of transport tissue (xylem)

15. 13.2 Living in water Xylem and Phloem - Transport systems in plants
Phloem transports sugars and other organic compounds through plant
Xylem transports water and minerals
See Chapter 9 section 3 pages 161 – 167

16. 13.2 Living in water

17. 13.2 Living in water

18. 13.2 Living in water

19. 13.2 Living in water

20. 13.2 Living in water
Distribution of marine life on rocky shores pp
Environmental factors change with position on shore
Zonation determined by tide
Rising tide submerges organisms in sea water
Falling tide exposes organisms to air
From low to high tide marks – graduation of increasing exposure to drying wind, sunlight, high temperatures during and low temperatures during night.

21. 13.2 Living in water Zones Supratidal – above high tide
Spray – between average high tide and extreme high tide
Intertidal – between average low and high tides
Subtidal – below average low tide

22. 13.2 Living in water
Sorrento Back Beach

23. 13.2 Living in water
Sorrento Back Beach

24. 13.2 Living in water Subtidal Zone Least stressful zone
e.g. algae – most abundant brown kelp (strongly attached to rocks by holdfasts)
Long floating fronds for photosynthesis, some have air-filled bladders
Small red algae (epiphytes) live on brown kelp.

25. 13.2 Living in water Intertidal (Littoral) Zone
Brown algae (Hormosira banksii) (also known as sea grapes or Neptune’s necklace)
Protected from drying winds and high temperatures by a covering of sticky mucilage and water-filled bladders.
Green and red algae live amongst brown algae.

26. 13.2 Living in water Intertidal (Littoral) Zone
Herbivorous and carnivorous molluscs live amongst algae.
Retreat into hard shells for protection.
Barnacles do not move; when exposed to air they close their hard shells, when exposed to sea water they open up and filter water for nutrients.

27. 13.2 Living in water Intertidal (Littoral) Zone
Rock pools provide places of refuge for sea stars, some fish, crabs, etc.
Water temperature varies greatly depending on depth, length of time of exposure to air

28. 13.2 Living in water Spray Zone Receives spray and splashes of water
Intense exposure to sunlight, evaporating water and concentrating salt
Extreme variations in temperature (day - night)
Few organisms live here
Tolerant of dry conditions

29. 13.2 Living in water Spray Zone continued
Cynobacteria (blue-green algae)
Crustose
Orange or yellow lichens
Snails
Supratidal Zone
Completely out of range of sea water.

30. 13.2 Living in water

31. 13.2 Living in water Adaptations to mangroves
Type of plant that can live in intertidal (littoral) zone on muddy soil
Fluctuating salinity levels (tides and freshwater from streams/rivers)
Lack of O2 at roots
Aquatic environment for seed dispersal

32. 13.2 Living in water

33. 13.2 Living in water

34. 13.2 Living in water

35. 13.2 Living in water Adaptations to mangroves Getting rid of salt
Some mangroves actively pump salt out at roots.
Some mangroves have salt-excreting glands on leaves

36. 13.2 Living in water Adaptations to mangroves Specialised roots
O2 normally enter roots through lenticels
Mangroves have evolved aerial roots, all of which have lenticels
These include peg roots, pneumatophores and silt roots
Pneumatophores increase surface area exposed to air for O2 uptake at low tide

37. 13.2 Living in water Adaptations to mangroves
Specialised roots continued
Cable roots spread laterally
Cable roots and pneumatophores provide stability for plant
Cable roots have fine hair-like roots that absorb nutrients and water

38. 13.2 Living in water Adaptations to mangroves Seed dispersal
Seed are buoyant and adapted for dispersal by water.
Some mangroves are viviparous (seeds germinate and young plants whilst attached to parental plant).
Young plants drop off with developing root system.
Can quickly establish in muddy substrate and not get washed away by waves