Spatial patterns and dimensions
Image: Kelp forest below the surface of the water.
Source : John Turnbull www.marineexplorer.org
Where are kelp forests found ?
Figure 6: Locations of kelp forest ecosystems around Sydney
Source: John Turnbull www.marineexplorer.org
Location of kelp forest ecosystems
Kelp forests are found in marine waters, close to the coast, in areas of the world that have temperate to cool ocean waters.
Temperate means moderate.
Temperate latitudes refer to the latitudes between the subtropics and the polar circles.
In these latitudes, temperatures are not extreme, but range between warm to cool and vary with the seasons.
Kelp forests can occasionally be found in some tropical areas but only where ocean currents move cold water to the area and reduce the temperature of the water.
Figure 7: shows global distribution of Kelp forests.
Source : Wordpress.com
Spatial distribution
Where are kelp forest ecosystems found across the world?
Large kelp forests are found off the western coast of North and South America, in the North West Pacific near Japan and Korea, in the south west Pacific including Australia and New Zealand and off the south and west coasts of Africa.
One estimate suggested that the world's kelp forests cover about 3.5 million square kilometres.
Figure 7: Shows the global distribution of kelp forests.
What are the conditions affecting the location of kelp forests?
Kelp forests grow near the coastlines of the continents because kelp generally grows on sub-tidal rocky reefs where water is shallower. However, kelp forests can also grow in water up to a depth up of approximately 30 metres.
Sub-tidal simply means below the tidal zone.
Kelp can grow very close to the shoreline when a rock platform is situated below low tide level. Kelp often grows on underwater rock platforms below low tide level.
See figure 8 of kelp growing on an underwater rock platform at the shoreline.
The holdfast of kelp plants grow on the rocky floor of the ocean, which is a part of the benthic zone.
The global distribution of kelp forests reflects the importance of climate in determining the location and nature of kelp forest ecosystems.
The climatic conditions which are essential for their survival are -
Cooler ocean water temperatures.
Sunlight - so that photosynthesis can occur. Kelp grows to (approximately) the edge of the Arctic and Antarctic circles.
Medium wave energy - frequent heavy storms and strong waves are not ideal conditions for kelp.
Where do kelp forests grow in Australia ?
In Australia kelp forests grow in cooler coastal waters, in the south-east, southern and south western regions of Australia.
View the map of Australia's kelp forests and observe the distribution of algal vegetation (kelp forests and beds).
In Australia, the species of kelp which dominates the forests and beds is 'Ecklonia radiata' also known as golden or brown kelp. This species grows in kelp beds on rocky reefs and can form dense 'forests' when normal growing conditions prevail.
'Ecklonia radiata' (E. radiata) can be found in the shallow intertidal zone to depths of approximately 25 metres. Other common species of kelp which grow along the east coast include 'Phyllospora comosa' (P. comosa) and on the southern coasts, include Bull kelp and Giant kelp which grow off the coast of Tasmania.
The location of Australia's kelp forests and beds correspond with the location of the 'Great southern reef'.
The Great southern reef (GSR) has been recently named to acknowledge the long rocky reef which extends over 8000 kilometres from the NSW/Queensland border along the eastern and southern coastlines of Australia to the south western coastline of Western Australia.
The GSR is made up of rocky reefs, kelp forests and both under-storey (which means under the main kelp canopy) and sea floor ecosystems. It is home to thousands of species, many of which are not found anywhere else in the world.
Given that the GSR covers an area of 71 000km2, the area covered by kelp forests in Australia can also be stated as that.
Figure 8: shows rock platform extending below low tide level with kelp growing underwater.
Source - John Turnbull www.marineexplorer.org
Figure 9: Location of Great Southern reef and associated kelp forests in Australia
Source: Australian Academy of Sciences
Concepts and definitions
Temperate, benthic, sub-tidal, inter-tidal, Ecklonia radiata, Great southern reef
Did you know ?
In science, plants species are abbreviated, so that 'Ecklonia radiata' is shortened to E. radiata.
Activities
Describe the location of kelp forests around the world using the terms temperate, cool, marine and coastal.
Describe the location of kelp forests in Australia using the terms temperate, coastal and rocky reefs. Name the states in Australia which have large kelp forests growing in their coastal waters.
Compare the location and size of kelp forests in Australia's kelp forests to one other marine vegetation.
Explain how the following factors affect the spatial distribution of kelp forest ecosystems across the world - depth of water, temperature of water, access to sunlight, wave energy.
Why is the location of kelp forests in Australia associated with the GSR?
Use the online tool the Atlas of Living Australia to search for the location of 'Ecklonia radiata' and 'Phyllospora comosa'. Compare their spatial distribution.
Use the The NationalMap. This online tool provides access to spatial data from Australian government agencies. Select 'add data' and type in marine and oceans and find a data set which shows bathymetry. Outline the connection between ocean depth and kelp location.
Refer to Figure 9 below and the Atlas of Living Australia to describe where Giant kelp grows. Briefly describe the Giant kelp ecosystem.
Figure 9: Giant kelp forest ecosystem occurring at various depths beneath the ocean surface.
Source: environment.gov.au