Kelp case study Flashcards
What makes an ecosystem vulnerable or resilient?
BELL, natural stress, human impacts
Why do ecosystems need to be managed and protected?
HUGIT
What percentage of temperate zones do kelp forests cover?
25%
Golden kelp
Ecosystem engineers –> habitat-forming species
Terms to describe parts of ecosystem
• Keystone species –> Southern Rock Lobster, Sea Otters (Northern California and Alaskan waters)
• Apex predator –> Great White Shark, Orcas
- Climax community –> when it is functioning at full capacity. Different for each ecosystem because of linkages and functioning (aim of management)
Countries where kelp forests exist and how many countries globally?
USA, Canada, UK, France, Norway, Denmark, South Africa, Japan, South Korea, Peru, Argentina, Chile, Iceland, New Zealand
–> 23
How far north and south can they grow?
10oS (Peru) and 66oN (Norway)
Where are kelp forests found?
On the west and south coast on continents near deep water up wellings
Biodiversity on the GSR
731 fish species, 4100 invertebrates and 978 seaweed species, 77% of which are endemic.
Note: there are 3x as many seaweed species on the GSR as there are coral species on the GBR (>3000 species of macroalgae on GSR)
How do kelp forests respond to east coast lows (large waves and flooding)
Natural resilience of kelp –> recolonising barren rock and high primary productivity as new blades grow - produce many spores for dispersal and fertilisation.
Flooding = increased turbidity –> interrupted solar energy transmission through water = decreased primary biomass productivity.
Increased nutrient loads (nitrogen and phosphorus) can cause eutrophication
Rate of change of kelp forests
- 38% of world’s kelp declined in past 50 years
- in aus, projections to 2100 predict an average loss of 62% of canopy forming seaweed
- 95% of Tasmania’s giant kelop forests have been lost, 98% in Norway, 90% in Canada
2% globally per year - rate/magnitude of change is father than ecosystem can recover
Climate change consequences
- ocean warming = kelp bleaching, reduced productivity and fewer spores
- increased magnitude and frequency of storms –> increased wave action, riping kelp from holdfasts (increased turbidity)
e. g. California’s coast, kelp south of point Conception had a 100% mortality rate during the winter storms - El Nino 97-98
Invasive species
- globalisation and climate change accelerated spread –> ballast water, aquaculture, biofouling on hulls, ocean currents
e. g. Northern Pacific sea star (ballast water) GSR effect native shellfish in Port Phillip Bay Area (food chain), lay 20 million eggs per sea star
e. g. cane toads - coastal wetlands and rainforests expanding ranges westward at 40-60km per year (affect red-belly black snake)
Urban development
- proximity to urban development
- discharge of polluted water (sewage) e.g. in Sydney, Lima, South Africa
- increased sedimentation etc. red tides produce potent neurotoxins, bioaccumulation
- increasing tourist value –> location near high populations
e. g. Japan 74% within 2km of coast near Tokyo (37million population)
e. g. palm oil in Sabah rainforests 40% gone
Overfishing
- overfishing of Southern Rock Lobster and Blue Gropers who are keystone predators –> for sea urchins
e. g. in 2012 Southern Rock Lobster was at <10% of natural levels - Blue Gropers are hermaphrodites - all born female. If juvenile fish caught before reaching sexual maturity, there will be an absence of breeding males in the community
Heritage value
- coastal areas of South East Australia are amongst the most densely populated regions of precolonial Australia
- Indigenous groups local inhabitants of GSR for 21,000 years
- Stewards of land and sea –> value for the biophysical habitat: conserving the ecosystems and sustainably managing marine resources –> celebrating important totems (e.g. Killer Whale, Sea Eagle and Black swan for Yuin people of Southern NSW) in ceremonies (songs, dances, story telling and other rituals)
e. g. Native people of Norway “Sami” people depend on kelp forests - shelter fish and species, food source BUT 80% kelp disappeared since 2002
Utility
- uses: products such as toothpaste, shampoos, align (extract from seaweed) used in Gaviscon to inhibit refluc, used to feed and look after animals, food source for aquaculture
- global seaweed industry valued at US$6 billion/year
- Economic important of GSR –> $38 million in tourism to Aus economy, $512 million into commercial fishing industry
Genetic
- More gentic diversity = more resilient to natural stresses and human impacts
- stronger linkages within foodweb, less likely for trophic cascade entire ecosystem
- kelp forests biodiverse –> extensive flora and fauna, biomass 1900mg/m2/year
- needs to be high levels of heterozygosity (differing alleles)
e. g. The Great African Seaforest
Intrinsic
- sustain aesthetic, spiritual, philosophical value needs to be genetically diverse to allow species to continue without threaten of extinction
- increasingly important as kelp forests becoming more wordly recognised as beautiful, underwater forests like rainforests
- spiritual awakening from tours
The need to allow natural change to occur
- allows species to adapt and survive in environment without disturbance of human intervention
- particularly important for kelp forests as act as carbon sink –> CO2 down in atmosphere and reducing ocean acidity
Spatial patterns and dimensions: location, altitude, latitude, size, shape and continuity
- Kelp forests are subtidal, extensive, rocky coast underwater ecosystems defined by their key component: the macroalgae kelp.
- they are located on the western side of continents in the cool waters of the temperate zone in countries such as USA, South Africa, Norway, New Zealand and Australia
- they are located near deep water upwellings between latitudes 40-60 degrees N + S (also 2-35m in depth)
- dominate 25% of the world’s coastal zones
- kelp are the trophic foundation of a complex food wed, multitude of flora and fauna
- west and south coast of 23 countries globally
- GSR –> extends 8100km from Byron Bay of Kallbari WA, diversity: 730 fish species, 4100 vertebrates, 987 seaweed species –> 77% of which are endemic
Weather and climate
Air and water temp: saline, 10-18oC, heat absorbed by kelp
Storms and wave action: deep water upwellings, large kelp ripped from holdfasts = large-scale die-back but regeneration, turbidity = increased nutrient absorption by kelp
Hydraulic
- west coast
- upwellings
- Kelp thrive where East Australian Current and Leeuwin Currents are weaker and cooler water is able to reach the coast (although this current is strengthening)
Geomorphic processes
- submerged rocky reef landscape (subtidal)
- shallow depths of continental shelf (if too deep, lack of available sunlight)
- continental drift of the indo-australian plate in NE direction = oldest and most diverse in Tasmania
- rocky reefs formed by erosion (wave action)
