Ecosystems at Risk - GBR

What are the spatial patterns and dimensions of the GBR

What are the spatial patterns and dimensions of the GBR

Location: off the east coast of northern queensland; stretches from the tip of cape york to lady elliot island

Latitude: Tip of cape york (8s), Lady Elliot Island (24S)

Size: 348000 km squared, made up of 2900 individual reefs, 35m deep inshore waters, 2000m deep in its depths. Comprised of fringing and barrier reefs, continental islands, coral cays and 70 different bioregions making it ecologically diverse

Shape: defined by the continental shelf of australia → 2000m dropoff

Continuity: over 500 000 years old

1500 fish species

6 turtle species

200 bird species

500 seaweed

600 echinoderms

125 sharks and rays

360 hard coral

What are the three environmental requirements necessary for coral reefs to form

Water temp → 17-29 degree range, 32 degrees causes bleaching, warm water essential for coral to grow. Coral bleaching leads to excess sugar development and polyp expels ZooX, polyp dies leaving white skeleton \n Sunlight → coral found in clear ocean water less than 50km deep \n Salinity → corals thrive in stable saline conditions. To much salinity causes stunting of growth, too little salinity causes ZooX to die

What are cyclone impacts (Atmosphere)

Positive → fast growing coral such as branching coral breaks easily but clears the way for slower growing coral to establish itself, cool ocean waters down reducing risk of bleaching events \n Negatives→ cyclones destroy, massive influx of fresh water can impact on salinity and turbidity levels, rivers can increase sediment load distributed over reef impacting on algal growth

what are Sediment (Lithosphere) impacts

Increases turbidity → affects light penetration in the water and thus affects photosynthesis process of coral polyps. Can also smother coral and seagrass beds → affects habitat

what are waves and currents (Hydrosphere) impacts

GBR is a barrier to wave energy creating a relatively calm lagoon behind it. Coral cays → like LEI rely on actions of waves to accumulate broken coral onto shoreline to build up the island. Coral polyps rely on ocean currents to deliver nutrients in form of algae/zoox to them to survive

what is coral spawning?

reefs produce solid limestone (dead skeletal remains of coral polyps) which are building blocks of the reef. New coral colonies build on the limestone structure of dead coral polyps. Spawning events cause new coral growth

explain the relationship of relationship of polyps and ZooX algae

crucial symbiotic relationship: Zoox algae produces sugars and oxygen for polyp through photosynthesis. In return, polyp provides nutrients for algae to survive.

What are some interactions that lead to diverse ecosystems

Cyclones (A) → coral establishment \n Limestone skeletons (L) \n Algae and coral poly[s (B) provide habitat and attract animals \n Algae (B) crucial to the food chain. Massive biodiversity within reefs is possible because of the amount of food available, massive rate of nutrient recycling within reef systems. Some fish actively feed on coral as a food source (parrot fish). Abundance of fish attracts higher order predators (dolphins/sharks) \n Fish interactions (B): smaller fish helping larger fish (cleaning parasites) \n Echinoderms: positive role in feeding on fast growing corals; allows slower species to grow \n Sharks, rays (B) impact on food chain \n Mantas (B) attracted due to continental shelf causing mass plankton \n Sea birds (B): fish in lagoons attract high number and diverse variety

what are some interactions that lead to efficient functioning of ecosystems

Water temp (H) \n Sunlight (A) \n Salinity (H) \n cyclones/storms (A) cooling water \n Sediment (L) \n Limestone skeletons (L) \n Waves and currents (H) deliver nutrients and accumulate coral on shoreline \n Algae and polyps (B) → growth of coral \n Algae (B) crucial to the food chain. Massive biodiversity within reefs is possible because of the amount of food available, massive rate of nutrient recycling within reef systems. Some fish actively feed on coral as a food source (parrot fish). Abundance of fish attracts higher order predators (dolphins/sharks) \n Crustaceans clean ocean floor; take in nutrients and expel clean sand \n Echinoderms (B) clean reef \n Sea birds (B) transport of seeds

What is the impact of earth movements on GBR?

continental drift: influences the growth rate of coral due to reefs moving into warmer waters, if water is too warm ZooX will leave the polyps causing bleaching

what is the impact of weathering on GBR

\n chemical weathering: coral's lime shells are broken down by chemical reactions. Ocean acidification (impact of climate change) causes reduced habitat and life, impacts food web as carbonate ions become less abundant which are needed for corals, oysters, crustaceans etc \n mechanical weathering: large waves and strong winds associated with cyclones may break apart and move large areas of coral. Biological weathering through parrotfish, molluscs etc break apart the coral and move them

Explain invasion and succession in GBR

closely linked with wind and wave energy. Plants are able to invade the cays by using waves and wind as transporters of their seed. Plants also use birds to transport partially eaten seeds → deposited onto islands in bird droppings → soil structures form causing pioneer species to invade/colonise the clay (grasses form → creates higher order plant communities)

Identify and explain 2 natural stresses on GBR

Cyclones

Major source of damage to reef, create huge waves that destroy coral, bring large amounts of fresh water which alters salinity levels, increased occurrence and severity due to global warming adjustment: coral spawning

COTS

Alters reef by eating coral polyps, in plague proportions it severely alters GBR. feeds on living tissue through the process of stomach eversion which breaks down polyp tissue. Leaves a white coral skeleton which is invaded by algae and worms adjustment: coral spawning, triton snail

what is the rate of change of cyclones/COTS

Cyclones: catastrophic

COT: Gradual in small proportions, catastrophic in plague proportions. Coral has low elasticity → sometimes takes 12-15 years for coral to reach its pre-infestation levels. If reinfestation of COTS occurs within the elasticity period it could alter GBR significantly

Determine vulnerability and resilience of GBR

Biodiversity

Immense biodiversity = resilient Extent

Large extent = resilient

Location

Effects of el nino events (bleaching) and cyclones. Proximity to coast → urban growth and mining = vulnerable

Linkages

Many linkages and varied given the biodiversity = resilient

Malleability

Complicated by threats from multiple sources and climate change. Never quite returns to pre stress state = vulnerable

Amplitude

Reached limit with bleaching events. Only getting worse with climate change. Multiple threats = vulnerable

Elasticity

Low elasticity rate, slow to recover = vulnerable

Outline negative human impacts on GBR (climate change) More extreme weather events

More extreme weather events

• Bleaching events

• Ocean acidification

• Turtle gender reliant on heat of sand

• Fish movement in line of cooler currents

• More rainfall meaning change in salinity levels

Outline negative human impacts on GBR (farming)

sugar cane/cattle

Land clearing= more surface runoff=more nutrient and sediment

• Runoff nutrient rich promotes algal growth

• Increased sediment in water smothers coral/sea grass

• Nutrient rich water supports COTS

• Unsustainable stocking leads to soil erosion

Outline negative human impacts on GBR (rec/commercial fishing)

• By catch (animals caught in nets indiscriminately drowning

• Fish strike

• Anchors cause damage

• Several aquatic species released

• Source of oil spills -Illegal activities in delicate zones

Outline negative human impacts on GBR (bulk carrying sea vessels)

• Anchors cause damage

• Source of oil spills

• Threats of running aground on shallow reefs -oil spills

• Spills, toxic paint

• More ships transmitting through reef

• Feral aquatic species released

• Fish strike

Outline negative human impacts on GBR (tourism)

• Trampling and souveniring of coral

• Close interactions with wildlife disrupt normal behaviour and impacts breeding cycle

Outline negative human impacts on GBR (mining)

• More mines= more greenhouse gases

• Port development requires dredging=turbidity=impact on fish

What are positive human impacts

COTS Culling program

Zoning

Education

Outline GBR zoning

Started in 2004 July \n Zoning defines allowed human activities in an area \n It protects marine environments (legally bound) \n 8 zones in plan with 4 covering 95% of the GBR \n o General use - all use allowed \n o Habitat protection - all use allowed \n o Conservation park - limited amount of fishing \n o Marine national park - no fishing just boating, diving, and photography \n Preservation zone is completely off limits \n Effectiveness - full coverage, (intergenerational equity - ensures that the next generations to come can enjoy and utilise the environment sustainably and a precautionary approach - ensuring that parts of the reef which are currently not damaged are maintained as a precaution) \n Ineffectiveness - only 1% is in the preservation zone, zone confusion regarding boundaries, tourism and fishing do still exist

Reasons for management and protection (Maintenance of Genetic Diversity)

Amazing diversity Wide array of animals rely on the reef, including one of the worlds most important dugong populations and six of the worlds seven species of marine turtle. Some 1625 species of fish swim among more than 450 species of hard coral

Reasons for management and protection (utility value)

tourism → creates money/jobs with 2 mil visitors a year

Recreation (sailing, boating, fishing, visiting)

Commercial fishing industry $200 mil

Reasons for management and protection (intrinsic value)

Connections with indigenous population (spiritual role)

Aesthetic value

One of the most beautiful ecosystems on earth, full of vibrant colours

Reasons for management and protection (heritage)

Words largest reef ecosystem, spiritual role

Reasons for management and protection (Need to allow natural change to proceed)

As an important reservoir for biological diversity, as it contains many undiscovered species To prevent coastal erosion: blocks strong waves that can erode coastal land

Explain the traditional approach to management

Indigineous peoples approached management by being stewards as there is an obligation to look after one's country because of the spiritual links with the land. \n Focus on using marine and terrestrial resources in a sustainable way \n Did this through a details practical knowledge of the ecosystem, its natural history and habitats, animal migration patterns and seasons \n Four underlying concepts that underpin their approach are: \n Subsistence→ traditional, indigineous communities are self-sufficient. They rely on the environment for basic needs \n Sustainability → reliant on continued access to environmental resources \n Custodianship → communities and individuals have responsibility to act as guardians/caretakers of environment \n Reciprocity → families and communities will pay back deeds/goods which have been given to them

Outline some traditional management strategies

Controlled access to reefs: Access restricted by customary tenure arrangements. Right to fish in a particular area is controlled by a clan/chief/family who regulate exploration of marine resources \n Fishing techniques: Traditional techniques and tools are fairly labour intensive but effective in catching organisms for consumption. They are low intensity, small scale and only allow for limited removal of species through spears and nets. \n Conservative harvest practised: only take what's needed \n Variety of species targeted rather than just one species \n Limits on size of fish \n Totems: Animal that clan is spiritually defined. Cannot be hunted \n Taboos: Sites where hunting is prohibited/restricted \n Nomadic Lifestyle: Groups moved regularly as hunters/gatherers. Allowed areas to regenerate and species to replenish. Low clan populations reduced stress on surrounding environment

Outline some contemporary managment strategies

Zoning \n Moorings: Allow boat skippers to tie up without use of anchors. Prevents damage created by anchors and anchor chains dragging along seabed \n Difficult to police due to size of reef \n Tourist Education: Promotes importance of environmental protection and impact of human activities on ecosystems \n Visitors to reef pay small fee which is used by GBRMPA to undertake education programs and manage ecosystem \n COTs culling: COTS BOT injecting bile salts/vinegar injections Repelling through triton snail mucus \n Boat Management: Speed limits enforced to reduce damage from waves \n Reef Restoration: Establishment of coral nurseries to regenerate coral communities