Case Study 1: Kelp Forests

Question 1

Nature of Global Kelp Forests

Answer 1

• aquatic ecosystems dominating 25% of the coastal zone of temperate regions
• 85% of temperate fish, 95% of molluscs, 90% of sea stars are unique to temperate reefs and kelp forests
• uses = recreation, tourism, commercial fisheries
• biomass productivity is comparable to terrestrial rainforests = 1900g/m2/year

Question 2

Characteristics of kelp

Answer 2

• macroalgae
• foundation of a sub-tidal habitat
• can grow up to 35m high, forming a canopy

Question 3

Kelp forests at risk

Answer 3

• natural stresses = urchin barrens, storms, ENSO
• human impacts = overfishing, urban development, human induced climate change
• decreasing at an average rate of 2% / year globally
• warming hotspot along East Coast of Canada sees a loss of 89% since 1982
• Norwegian coast sees loss of 80% since 2002
• 95% of tasmania’s giant kelp forests have been lost

Question 4

Nutrient Cycles

Answer 4

• High biomass productivity + biodiversity
• nutrients is removed by human activity through overfishing, and added runoff
• overfishing of apex predators (bronze whale shark) results in trophic cascades, causing disequilibrium + overfishing of key stone predators like southern rock lobster reduces kelp cover due to urchins increasing population
• runoff: increased turbidity due to algal blooms (eutrophication), reducing sunlight

Question 5

Energy Flows

Answer 5

• energy from sun is used by primary producers through photosynthesis, flowing to herbivores, carnivores, apex predators and decomposers
• loss of energy through each level results in decreased population
• energy availability is dependent on sun exposure

Question 6

Spatial patterns and dimensions of kelp forests

Answer 6

• dominates rocky coastal environments in temperate latitudes in 23 countries globally
• covers 25% of the world’s coastlines in waters of 2-35m depth
• most prolific coastal ecosystem in NZ, South Africa, Chile, UK, Japan, Iceland, Russia
• found between latitudes 40-60 degrees North and South of the equator –> can survive lats of 10 degrees (peru) and 66 degrees (norway)
• ideal water temp = 10-18 degrees C
• west coast of continents (cold ocean currents, deep water upwelling)
• greatest density found in the Northern pacific ocean on the coasts of Japan and the US

Question 7

Kelp Forests of the GSR - location

Answer 7

• 8100km in length, covering 79 000km2
• made of thousands of individual reefs that stretch over 6 Australian states along the southern half of the coastline
• extends from latitudes 27 degrees S to 45 degrees S
• depth of 2m to 35m
• extends from Brisbane (27’S,153’E) to Kalbarri, WA (28’S, 114’E)

Question 8

Biodiversity of the GSR

Answer 8

• global diversity hotspot, 77% of species are endemic (such as weedy sea dragon, giant Australian cuttlefish, Australian fur seal)
• 731 fish species, 4100 invertebrates, 978 seaweed species

Question 9

Dynamics of Weather and Climate

Answer 9

• Air and water temperature
• Storm and Wave Action
• Hydrologic processes: thermal temperatures and ocean currents,
• Geomorphic Processes
• Biogeographical processes

Question 10

Dynamics of weather and climate: air and water temperature

Answer 10

• ideal water temp: 10-18 degrees C (however; can be found as warm as 24 degrees in QLD and as cold as 5 degrees in Greenland)
• ocean temps are influenced by air temps as heat is absorbed and transported away from the equator
• thermal stress on kelp forests a more likely to occur at latitudes lower than 20 degrees and higher than 40

Question 11

Dynamics of weather and climate: storm and wave action

Answer 11

• ocean currents drive ocean temperatures
• cold water currents flow over the west coast of continents and result in deep water upwelling, increasing nutrients
• in Aus, kelp forests thrive in areas where cold water is from the West Australian current and Antarctic circumpolar events (away from the warm water currents of EAC and Leeuwin)

Question 12

dynamics of weather and climate: geomorphic processes

Answer 12

• require hard, submerged rocky reef substrate to anchor to (found along fringing waters of coastlines) in shallow depths of the continental shelf
• reefs that are too deep = limited sunlight and may be too cold in extreme latitudes
• locations close to steep continental slopes may be more productive as there is larger swells and regular deep water upwelling
• erosion forms rocky reefs, wave action creating diverse habitat of holes in softer rock (limestone) and cracks in harder rocks (sandstone)
• diversity of rock substrate and relief facilitates the diversity of kelp forests

Question 13

dynamics of weather and climate: biogeographical processes

Answer 13

• primary succession
• kelp acts as a pioneer species by colonising rocky substrate
• secondary succession
• invasion
• modifications

Question 14

primary succession:

Answer 14

• primary succession: gradual growth of plant life in an ecosystem where there was previously no vegetation / soil (eruption of underwater volcano creates a seamount that is void of plant life)

Question 15

secondary succession

Answer 15

• secondary succession: when plants and animals are replaced in a location that has been disturbed but previously supported life (e.g. urchin barrens may be replaced by kelp forests following the release of kelp spores from a neighbouring community)

Question 16

invasion:

Answer 16

follows a disturbance (ENSO) and results in increased species diversity and ecosystem resilience

• can also negatively impact diversity if a new species destroys the foundation of that ecosystem, replacing it with another
• e.g. tropicalisation of herbivorous fish to kelp forests

Question 17

modifications

Answer 17

occur when species + ecosystems adapt to change

• rapid growth in local urchins can be countered by a relative growth in local lobster populations leading to ecological balance
• species might also migrate in response to change (changing patterns in ocean currents)

Question 18

important species in the GSR:

Answer 18

ecosystem engineers: golden kelp
keystone species: southern rock lobster
apex predators: great white shark

Question 19

ecosystem engineer

Answer 19

an organism that creates / maintains a habitat, having a large impact on the species richness

Question 20

keystone species

Answer 20

a species that has a disproportionate impact on the ecosystem in comparison to its population, largely affecting the ecosystem

Question 21

apex predator

Answer 21

a predator at the top of the food chain (occupying the highest trophic levels) that does not have natural predators

Question 22

natural stresses

Answer 22

• storm and wave action (East Coast Lows)
• invasion (predator / prey imbalance)
• ENSO (La Nina)

Question 23

Storm and Wave Action (East Coast Lows) as a natural stress

Answer 23

• plant attaches to seafloor with haptera (holdfasts) that keep them rooted to the substrate
• life expectancy of kelp is 7 years and unpredictable as they are vulnerable to large storms
• combination of warmer waters with fewer nutrients, new invasive species and overgrazing as well as more severe and frequent storms due to climate change is making them vulnerable
• tasmania’s east coast

Question 24

Tasmania’s East Coast - Storm and Wave action

Answer 24

• 95% of the kelp has disappeared since the 1940s
• it is now enlisted as an ‘endangered ecological community’ - this being the first time the country has given protection to an entire ecosystem
• temperature of waters have increased by approx 2.5 degrees, introducing the invasive species to consume the kelp, which is exacerbated by the overfishing of of rock lobsters

Question 25

Invasion - predator / prey imbalance

Answer 25

• urchins pose the biggest threat to reefs in port Philip bay and the over abundance of long-spined sea urchins is increasing
• the infestation in Northern Port Philip bay was noticed during the millennium drought, which forced urchins to turn to algae as a primary source
• deteriorating macroalgae lead to the infestation of japanese kelp, transported through ballast water
• overfishing of southern rock lobster has added to this

Question 26

ENSO (la nina)

Answer 26

• stands for El Nino Southern Oscillation
• La nina = the positive phase of ENSO; sustained positive SOI (southern oscilation index) values and extensive cooling of the central and eastern tropical pacific ocean, accompanied by warmer than normal sea surface temperatures in western pacific ocean
• La Nina is associated with increased probability of wetter conditions over much of Aus, and higher numbres of tropical cyclones
• changes to the atmosphere include: sustained cooler SST across central and eastern tropical pacific ocean, increased convection/cloudiness over tropical australia, PNG, indonesia; increase in strength of trade winds, sustained positive values of the SOI above 8+

Question 27

Adaptations of golden kelp

Answer 27

holdfasts (haptera) 60 cm wide to keep anchored

gas bladders (pneumatocysts) keep upper portions of kelp afloat, more sunlight and nutrients due increased surface area

Question 28

Adaptations of Southern rock lobster

Answer 28

hard shell for protection

feeds at night

Question 29

Adaptations of leafy sea dragon

Answer 29

camouflaged to appear a floating seaweed

males are responsible for child bearing

Question 30

types of adaptation

Answer 30

behavioural: responses made by the organism
physiological: body processes
structural: features of an organisms body

Question 31

Natural stress

Answer 31

ENSO, severe storms, urchin outbreaks

Question 32

Human impacts

Answer 32

marine heat waves (Kalbarri WA), kelp bleaching, tropicalisation and urchin barrents (all CC)

overfishing 
urban development (pollution, introduced species, tourism

Question 33

Kelp trajectories within different regions

Answer 33

• southern intrusion of the Eastern Australian Current has expanded the range of sea urchins
• high temperatures from the ‘warm blob’ in Northern California triggered a population boom of purple sea urchins
• 38% of the world’s kelp forests have declined over the past 50 years
• in Australia, projection to 2100 predict an average loss of 62% of canopy forming seaweed

Question 34

Human impact - climate change

Answer 34

• greatest long-term threat to kelp forests
• caused by global emissions of green house gases (CO2) from burning fossil fuels, land clearing
• current concentration of CO2 in atmosphere is the highest in the last 800 000 years
• 1 degree Celsius increase in global average temperature since preindustrial time (1990)
• the warmest 20 years on record have all occured since 1990
• by 2100, sea temps of SE Aus would be 2.5 warmer
• increase in marine heatwaves
• increase in extreme ENSO

Question 35

the ocean as a sink

Answer 35

• 90% of all excess heat in our atmosphere is stored in oceans
• oceans have absorbed 30% of emitted CO2 from human activities since 1990
• average reductions of between 0.06 and 0.32 ph units over the next century

Question 36

climate change - WA marine heat wave 2011

Answer 36

• indian ocean off WA is a hotspot where rate of ocean warming is in top 10%
• temperature increase of 0.65 degrees over 50 years
• warmer temps are shifting southwards - 20 -50 kms a decade
• 2011: summer temps reached 2-6 degrees above longterm averages across 2000km coastline

Question 37

impacts of the marine heat wave

Answer 37

• loss of kelp forests across 1 million ha of reef in NW GSR and 100km range contraction of canopy forming seaweeds –> risk of species extinction, lack of suitable habitat retreat farther south and high rates of endemism
• kelp forest declined by 43% from 2011-2013, the range of forest cover decreasing by 100km, area shrinking by 370km2 –> based on surveys of 65 reefs along WA coast
• replacement of kelp forest with turf

Question 38

climate change: kelp bleaching

Answer 38

• whitening of macroalgae due to loss of pigments used for photosynthesizing as a result of stress (typically thermal stress and ocean acidification)
• water temps above 24 degrees for greater than 2 weeks can result in bleaching
• 50% of the GSR display bleaching symptoms

Question 39

climate change - tropicalisation of herbivorous fish and expansion of urchin barrens

Answer 39

• warm temperature and tropical species are expanding poleward and increasing in abundance
• strengthening of warm water current (EAC and Leeuwin)
• subtidal sea urchin, intertidal invertebrates, zooplankton, tropical fishes have expanded into temperate aquatic ecosystems
• sea urchins: range extension and population expansion leads to overgrazing, barren formation, reduced fishery productivity
• SW GSR: tropical herbivorous fish (surgeonfish) are preventing recovery of kelp forests
• tropical fish inhabiting as far south as Sydney (cabbage tree bay, manly)
• tasmania has moved from 3% urchin barren to 30% since 1978
• advancing poleward at 160km / decade

Question 40

future outlook of tropicalisation

Answer 40

by 2020, 20% increase in the mean flow of the EAC

- 50% of Tasmania’s coast will become barren if warming continues

Question 41

human impact - overfishing

Answer 41

• when fish are caught at a rate higher than replacement

- 29% of commercial species were overfished or vulnerable to overfishing

Question 42

human impact - overfishing in the GSR

Answer 42

GSR

• blacklip abalone and southern rock lobster = 2 most valuable commercially fished species in shallow, rocky reefs
• rock lobster stocks hit historical lows of less than 10% of natural levels in 2012
• intensive fishing has reduced the stock of legal sized lobster on Eastern reefs to approx 2-8% of pre-fished biomass by 1990
• fishing has reduced the abundance of large lobsters capable of preying on urchins

Question 43

human impact - overfishing in tasmania

Answer 43

• Northern Tas: stock numbers have reduced by 90%

0 lobsters capable of preying on urchins are 138mm, much larger than recreational size limits 110mm

Question 44

impacts of urban development

Answer 44

• localised pollution including nitrogen enrichment from discharge of sewage and storm water
• 70% of Australians (16 million) living within 50km of GSR
• increased sedimentation (turbidity)
• chemical pollution from industry areas like Port Botany and Port Phillip Bay
• Sewage and Crayweed: until the late 1990s, sydneys beaches were polluted with 1 billion L of untreated sewage daily causing extinction of crayweed

Question 45

impact of urban development - eutrophication and red tides

Answer 45

• excess of nitrogen and phosphorus causes eutrophication with overgrowth of algae, which consume oxygen and block sunlight
• red tides contain potent neurotoxins and bacteria that kills fish and poison humans

Question 46

tourism :(

Answer 46

• reef supports activities worth 10 billion annually
• reef and adjacent coast = 40 billion annually
• sediment runoff from increased stormwater discharge increases turbidity
• byron bay: stress of 1.7 million visitors during summer periods

Question 47

Introduced Species

Answer 47

• Australia has 250 introduced marine species
• transported: ballast water, biofouling on hulls, aquarium imports, ocean currents
• daily, 3000 species of marine organisms transported around the world in the ballast water
• Japanese seaweed and Northern pacific seastars are examples

Question 48

The Northern Pacific Sea Star

Answer 48

Port Phillip Bay: composed of 54% of fish biomass as it spreads rapidly
has major impact on native species, as it feeds on native shellfish, worms, sea stars

Question 49

Japanese Seaweed :)

Answer 49

spreads naturally through the millions of spores released by each organism and through biofouling.

can form dense forests, resulting in competition for light and space

Question 50

Reason for protection: Heritage: Indigenous

Answer 50

• Yuin nation made of the Walbanga and Djirangang peoples, traditional owners of the Eurobodalla Shire
• Montague Islands feature artefact scatters and middens
• islands are used for traditional ceremonies, food, and places of education for men
• dreaming stories link the island to mainland’s gulaga
• murrarang aboriginal area = south coast’s largest midden, lagoon north of healdnad is home to serpent associated with traditional beliefs regarding creation

Question 51

Reason for protection: Heritage: Post-colonial scum

Answer 51

1851: Moruya was the centre for Eurobodalla’s development
1880: shipbuilding began to thrive in Bateman’s Bay
1881: lighthoues was built on Montague Island
19th century = commercial fishing began
20th century = oyster farming
- more than 10 shipwrecks, including John Penn and the Lady Darling

Question 52

Reason for protection: Utility: Globally

Answer 52

• Ecosystem services: $43 000 per hectare per year (grossly inadequate figure as limited studies done on their value)
• Kelp harvesting: 16.8 billion (2016)
• acts as a carbon sink, with high rates of absorption (around 30 - 60 x the rate of landbased plants)

Question 53

Reason for protection - genetic diversity

Answer 53

• 77% of species in the GSR are endemic
• -> seaweed = 40-77%
• -> invertebrates = 22-56%
• most productive aquatic ecosystem, 1900g/m2/yera
• 731 fish species, 4100 invertebrates, 978 seaweed species
• 29% of species are overfished / vulnerable to overfishing
• Northern Tas - lobster stock reduced by 90%
• bateman’s marine park = breeding place for over 40 000 sea birds, a nesting site for 8-12000 little penguins (Aus’s only penguin)

Question 54

Intrinsic Value

Answer 54

• place for 40 000 sea bird and nesting site for little penguins
• can be seen from space
• 2.7 million surfers surf a location i the Southern Reef (e.g. the Box, Margaret River Valley, Seal Rocks, Bells Beach)
• 2.5 million domestic and international tourists / year to the GSR annually

Question 55

Reason for protection: utility - GSR

Answer 55

• Ecosystem services: $187 billion per year
• Tourism: $38 million per year
• Commercial fisheries: $512 million per year
  (rock lobsters = $376 million, abalone = $136 million per year)
• Kelp harvesting: $3 million with projected values of $1000 million (2025), and 1.5 billion (2040)

Question 56

The need to allow natural change to occur:

Answer 56

• an area of enormous biodiversity, most not yet discovered (i.e. upwards of 10 000 species not yet discovered)
• allows for discoveries from observing ecosystem (medical, scientific)
• offset the increase in climate change through being a carbon sink

Question 57

Traditional and Contemporary Management

Answer 57

Traditional:

• hunting, gathering, nomadism, stewardship, ranger program
• native title claims

Contemporary

• zoning and marine parks
• ecological restoration (lobster restocking and urchin culls)
• citizen science (reef watch)
• kelp restoration / habitat restoration

Question 58

Traditional: hunting, gathering, nomadism, stewardship, ranger program

Answer 58

Local + regional

• knowledge of 21000 years
• middens and artefacts have been retained
• 120 ranger groups
• employed 2500 indigenous peoples

Question 59

Traditional: native title

Answer 59

Regional, national

• recognised over approx 32% of Australian land and waters
• South Coast claim covers 17000km2, extending to national parks, state forests, council lands, crown land
• 52 indigenous groups and more than 850 members of the Yuin community now have traditional fishing rights

Question 60

Zoning + marine parks

Answer 60

Regional + federal
Positives:
Conservation of biodiversity and ecosystems, protecting breeding, nursery and feeding habitats.
Providing benefits in long term research and also sanctuary zones protect fish and may benefit adjacent fisheries through spill over.

Negatives
Raises the profile of an area for marine tourism. Only 20% of marine park area in NSW is ‘no-take’, only 7% of the coast is protected from fishing. Commercial fishing is allowed in 80% of the waters within marine parks, and recreational fishing occurs in 97% of commonwealth waters. MPAs increase concentration of commercial fishing activity.

Example: Bateman’s Bay Marine Park
Covers an area of 850 km2
Sanctuary zones cover 25% of park
Over 80% of the park is open to recreational fishing and commercial fishing is limited to general use zones (50% of park).

Question 61

Ecological Restoration

Answer 61

Involves reducing catch limits through legislation, lobster restocking and harvesting and cull of long-spined sea urchins.
Legislation (regional)
- Tasmania: cut recreational and commercial fishing by more than 50% since 2013. Reduction of recreational fishers from 5 lobsters to 2. Recreational rock lobster harvests reduces from 55t (2013) to 35t (2019)
- SA: closes the rock lobster season for one month each year between September and November to allow sotcks to rebuild
- WA: fines, individuals who illegally fish abalone and lobster could face 4 years imprisonment or fines up to 400 000

Lobster restocking is used in MPAs and has been shown to improve lobster yield at the release site by 60%. 30 000 lobsters per year have been relocated from healthy reefs in Southern Tasmania to at risk reefs in northern Tasmania.
Over the last 3 years, 145 000 lobsters have been translocated along the coast of Tasmania.

Commercial and recreational divers are subsidised $0.75/kg for harvesting or culling urchins. The total weight of sea urchins harvested under the program is over 750 tonnes, amounting to 2 million urchins.

Question 62

Citizen Science - Reef watch

Answer 62

Local and regional
More than 5700 volunteers.
Increased stewardship through the ‘adopt a reef’ program.
Data is gathered to support management of these ecosystems. For example, snorkellers and divers look for ‘bioindicator species’
Limitation = only monitoring sites <6m in depth and clustered close to major metropolitan areas.

Australian research council over the last years has awarded 55 million dollars to coral reef research and only 4 million dollars to temperate reef research.

Question 63

Kelp restoration / habitat restoration

Answer 63

Regional
SIMS has over 100 scientists, representing broad skills in marine science.
Healthy, fertile adult crayweed plants are removed and attached to deforested rocks using biodegradable mesh – increasing reproductive rates. Crayweed transplanted onto Sydney’s reefs generally survived (40-70%) and reproduced 5-12 recruits per o.1m2 after 1 year.