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

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.

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

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

13.2 Living in water Abiotic factor – Temperature

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

13.2 Living in water Abiotic factor – Light

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

13.2 Living in water

13.2 Living in water

13.2 Living in water

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.

13.2 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.

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)

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

13.2 Living in water

13.2 Living in water

13.2 Living in water

13.2 Living in water

13.2 Living in water Distribution of marine life on rocky shores pp. 248-249 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.

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

13.2 Living in water Sorrento Back Beach

13.2 Living in water Sorrento Back Beach

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.

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.

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.

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

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

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.

13.2 Living in water

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

13.2 Living in water

13.2 Living in water

13.2 Living in water

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

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

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

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