Reef ecosystems

Rocky reef program

We monitor our reef ecosystems using underwater surveys to support conservation of these key marine habitats and identify potential threats. Explore our data and methods and discover how citizen scientists are helping us to build a better picture of our reefs.

Sub-tidal reefs are one of our critical marine habitats that support local marine biodiversity and productivity. Across metropolitan Adelaide and the Fleurieu Peninsula, our network of reefs offer valuable shelter, breeding grounds and food for a variety of marine life including bony fish, sharks, rays, shellfish, and other invertebrates. Our reefs, like those found elsewhere in Gulf St Vincent and surrounding waters form part of the Great Southern Reef (GSR) ecosystem that spans Southern Australia.

The allure of these underwater landscapes attracts tourists, including snorkelers, divers, and nature enthusiasts, and at the same time supports commercial and recreational fishers.

Photo: M. Katz

Why monitoring?

Building knowledge of the marine biodiversity associated with our reef ecosystems enables us to track how they may be changing. This includes:

  • identifying new disturbances or threats
  • improving knowledge on certain species to support their conservation.

This important biodiversity information is critical to:

  • maintaining knowledge and informing future management actions to retain the balance of biodiversity in the region
  • helping us to educate the community about the diverse reef ecosystems throughout greater Adelaide.
Blue devil Photo: M. Katz

How do we measure them?

We conduct underwater reef surveys using Reef Life Survey (RLS) methods. This enables us to understand the complexities of reef biodiversity and maintain a consistent approach that can be used to compare the health of our local reef biodiversity to others found interstate and nationally.

Underwater surveys RLS methods. Photo: A Cooper

This has involved data collected from scientists and volunteer divers trained as part of our Reef Life Survey citizen science program.

RLS volunteers. Photo: A Cooper

Indicators

We collect a range of information called “indicators” to assess reef biodiversity. These measurements include:

Fish and invertebrate biodiversity & species richness

Species richness refers to the total count of fish and invertebrate species documented at a site and serves as a biodiversity indicator. Consistent or increasing species richness over time indicate positive reef condition.

Community structure

Community structure refers to the types and numbers of species present at each location, and how they relate to each other. Assessing community structure can be useful to identify changes to food-webs, biodiversity, and how reefs recover from disturbance over time.

Size and abundance of large fish

Large fish (those exceeding 200 mm) typically produce more offspring and help regulate predator-prey dynamics. Consistent or increasing numbers of large fish over time indicate positive reef condition.

Habitat cover

Macroalgae (seaweed) provides habitat for marine animals to live in. Macro-algae habitat is measured as percentage canopy cover over a site. Consistent or increasing macro-algae canopy cover over time indicate positive reef condition.

Reef fish thermal index

Many reef communities contain species adapted to various temperature ranges. Global warming may lead to the replacement of cooler-adapted species with warmer-adapted ones. The reef fish thermal index helps us to assess how reef communities may respond to climate change.

The GARR program is a collaborative initiative between Green Adelaide and the Marine Science Team, Department for Environment and Water. Information collected from this program contributes to Green Adelaide’s Strategic Plan and Performance Reporting Framework, State of Environment Reporting, State Report Cards and nationwide Reef Life Survey (RLS) supporting the Integrated Marine Observing System (IMOS) database enabled by the National Collaborative Research Infrastructure Strategy (NCRIS).

Want to know more?

Explore our Reef Ecosystems dashboard to find the locations and types of marine species found across metropolitan Adelaide and the Fleurieu coasts.

Learn more in our reports: