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Rocky Shores

Rocky outcrops in coastal areas (including sub-ecosystems of platforms, rock pools and boulder fields). Characteristic vegetation may include seaweeds (algae), lichens and microscopic plants.

 

MILLENNIUM ECOSYSTEM ASSESSMENT REPORTING CATEGORY

Coastal Ecosystems

 

What ecosystem functions do rocky shores perform?

Wind and waves shape rocky shores sometimes breaking rock into unconsolidated materials.

Rocky shores on N. Stradbroke Island protect inland ecosystems and island structure.

A combination of temperature, wind, waves and tides shape rocky shores. Particulates in wind and water cause abrasion, along with unconsolidated rock that may roll around with the ebb and flow of waves and tides in crevices and rock pools. Waves can pound these hard substrates and water stored in crevices and pools can expand and contract as temperatures change. The location of rocky shores at the interface of terrestrial (land) and marine ecosystems means rocky shores perform unique functions relative to other ecosystems (as shown in Table 1).

Through their hard physical structure rocky shores regulate disturbance to other coastal ecosystems by stabilising inshore sediments, building islands and other physical structures (such as coral reefs). For example Stradbroke Island was formed by the retaining role that rocky shores provide. A rocky headland trapped and accummulated sand providing the foundations from which vegetation could grow, binding sand particles and eventually forming an island.

Many animals and plants have adapted to live in these harsh conditions, which include storm surges, waves and winds.  Life in the flunctuating high and low tidal zones (the intertidal zone) provide challenges of both water inundation, exposure to the sun and possible predators. Plants and animals must tolerate the salty conditions and extreme changes in temperatures. Plants must also tolerate the lack of nutrient rich soils, soft or unconsolidated substrate in which they would otherwise use to grow and anchor themselves in other types of ecosystems. These harsh conditions provide natural biological control.

Rocky shores provide niche habitat for unique and unusual species of seaweeds, lichens, microscopic seaweeds, snails and limpets, barnacles, crabs, sea squirts and anemones. The structure and biological composition of rocky shores provide important shade and shelter, roosting, feeding and nursery areas for birds, fish and other species. Depending on its location, a rocky shore may be in an exposed or sheltered area. Of all seashore habitats, the sheltered rocky shore is generally more biodiverse, having larger numbers of species in greater abundance. Unique educational and research opportunities are provided by rocky shores and their diverse genetic resources.

 

Table 1:The relative magnitude (to other Ecosystem Reporting Categories) rocky shores perform each ecosystem function.

Ecosystem Function Category Ecosystem Function 0
1
2
3
4
5
Regulating Functions
Gas Regulation            
Climate Regulation            
Disturbance Regulation            
Water Regulation            
Soil Retention            
Nutrient Regulation            
Waste Treatment and Assimilation            
Pollination            
Biological Control            
Barrier Effect of Vegetation            
Supporting Functions
Supporting Habitats            
Soil Formation            
Provisioning Functions
Food            
Raw Materials            
Water Supply            
Genetic Resources            
Provision of Shade and Shelter            
Pharmacological Resources            
Cultural Functions
Landscape Opportunity            

 

What types of rocky shores are in SEQ?

There are two main types of rocky shores. Both these types of rocky shores also contain habitats such as platforms, rock pools and boulder fields, each containing their own unique species of fauna and flora. The two types of rocky shores are:

1/ high energy shorelines generally exposed to open seas; and
2/ low energy shorelines generally located in sheltered bays.

Plants and animals in rocky shores grow in different areas (zones). Three major zones can be identified on rocky shores: the splash zone, the littoral zone and the sub-littoral zone. Plants grow in areas depending on their ability to withstand time in and out of water (inundation and dessication). Plant growth zones are usually quite evident due to the stationary nature of plants. Although animals have similar zonation also based on their ability to withstand water inundation, sun and air exposure, animal zonation is not as obvious because they are generally mobile.

 

What is the area and extent of rocky shores in SEQ?

 

Threats to rocky shores can include fossicking and pollution from oil spills.

Links to other publications and websites

WetlandCare Australia
Caring for Rocky Shores
Marine Discovery Centre
AU Govt - Climate Change Risks
Journal of Marine Bio. and Eco.

Rocky shore ecosystems cover approximately 5 km2 of SEQ. This map shows rocky shores can often be found in high energy zones in SEQ such as Point Arkwright, Mudjimba Island, Point Cartwright, Caloundra Headlands, Redcliffe Peninsula, Cape Moreton, Point Lookout on North Stradbroke Islands and Burleigh Heads.

 

What is the vulnerability of rocky shores and threats to this ecosystem in SEQ?

Rocky shores are a robust and resilient ecosystem able to withstand extreme natural forces such as wind, rain, waves, sun exposure and low nutrient conditions. The greatest threat to rocky shore ecosystems is physical disturbance through human actions relating to fossicking and collecting. Many species (particularly those that shelter under rocks) are sensitive to light and are often crushed through trampling and the movement of rocks. It is important to leave rocks and shells where they are found. If seaweeds are attached to rocks do not try to pull them off and if handling animals do so with great care, returning them to the same position they were found. Over collecting of organisms (particularly gastropods and shellfish) is a recognised threat to this ecosystem hence the restrictions on the number of these organisms available for collection.

Pollution is the second greatest threat to rocky shore ecosystems. Pollution from oil spills and sewerage can unbalance the delicate foodweb, as was seen in 2009 during the oil spill in Moreton Bay. Human litter (e.g. plastic bags and fishing line) not only impact on the aesthetics of an area but can also attract pests (e.g. rats) and affect life on and around these ecosystems. Rising sea levels and changes in the temperature and chemical composition of the seawater due to climate change will also have an impacting factor on rocky shores in the future.

  

How do we manage rocky shores in SEQ?

The Queensland Government's Department of Environment and Heritage Protection is the state agency with responsibility for the management of rocky shore ecosystems. The main enforcing legislation protecting rocky shores through this agency is the Nature Conservation Act 1992. The Queensland Government's Department of Agriculture, Fisheries and Forestry provides the rules for collecting and fossicking on rocky shores. Some protection of rocky shores are provided under the Moreton Bay Marine Park Plan and further protection is provided under the Ramsar Convention.

Wetlandcare and Coastcare have community engagement programs aimed at better managing rocky shore ecosystems across Australia.