The physical environment
Photo: Shutterstock
Photo: Shutterstock
Great Southern Reef Kelp Forests
The unique characteristics of the Great Southern Reef kelp forests result from interactions in the natural environment. The lithosphere, atmosphere and hydrosphere create the conditions required for kelp forests to grow.
Kelp are the foundation species (primary biomass) of the ecosystem (food webs, energy flows and nutrient cycles). The high primary productivity of kelp supports high levels of biodiversity.
Background photo: John Turnbull. Diagram: L Chaffer
Conditions kelp forests need
Rocky outcrops for kelp to attach to
Sunlight for photosynthesis to produce primary biomass
Low turbidity (clear water) to maximise sunlight penetration
Cool water - less than 20 °C is best (Maximum 26 °C)
Normal seawater pH levels (8.1 - alkaline) and salinity (35,000 ppm compared to freshwater at less than 1,000 ppm)
Nutrient rich water. Seasonal upwelling events provide essential nutrients.
Low to moderate wave energy although some species can survive on high energy coasts.
These conditions are found on rocky reefs in Australia's temperate latitudes.
Golden Kelp
Golden Kelp (Ecklonia radiata), the dominant species on the GSR, thrives to depths of approximately 30m and forms dense 'forests' in the most sheltered locations, however it is also known to grow to depths of 50 metres in Eastern Tasmania.
Other kelps and algae co-exist with Golden kelp where conditions suit. Giant Kelp mostly grows on reefs with moderate wave action and Bull Kelp is found in very high wave exposed locations such as Tasmania's west coast.
A rocky reef in the Derwent River Estuary, Tasmania, supporting a diversity of habitats such as kelp and sponges, and hundreds of different marine species in a small area.
https://www.derwentestuary.org.au/rocky-reefs-kelp-beds-and-inter-tidal-zone/
Use the INTERACTIVE VERSION of this illustration to identify species here: https://www.derwentestuary.org.au/rocky-reefs-kelp-beds-and-inter-tidal-zone/
VISIT THE SUBPAGES to investiage the biophysical environment of the GSR:
The Lithosphere
The Atmosphere
The Hydrosphere
The Biosphere
The model below summarises the processes and functions of kelp forests on the Great Southern Reef ( the example is in South Australia).
Source: Imgraben, S., Peters, K. and Brock, D. (2019). Conceptual models of nearshore reefs in the Adelaide and Mount Lofty Ranges region. DEW Technical note DEW-TER-2018-10, Government of South Australia, Department for Environment and Water, Adelaide