The physical environment

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.

• 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 (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.

Use the INTERACTIVE VERSION of this illustration to identify species here: https://www.derwentestuary.org.au/rocky-reefs-kelp-beds-and-inter-tidal-zone/

CONCLUSION: KELP FOREST ECOSYSTEM FUNCTIONING

The model below summarises the processes and functions of kelp forests on the Great Southern Reef ( the example is in South Australia).