Recent underwater surveys at Port Coogee Marina have revealed 180 species of non-fish fauna thriving at the popular Cockburn coastal attraction.
Following a series of earlier fish-focused investigations, the latest discoveries included a range of tiny sea critters including 118 species of Molluscs, Arthropods and Chordates, the three most common groups to be identified at the marina between February 2023-2024.
Some of the Molluscs included commonly known Bivalves like the Venus Clam and Southern Hammer Oyster, Cephalopods like the Star Octopus and Australian Giant Cuttlefish, and Nudibranchs like the colourful Gem Doris and showy Rostrata Egg Ribbon.
Arthropods included Crustacea like Decorator, Little Porcelain and Australian Blue Swimmer crabs, while Chordates included Lightbulb Sea Squirts, the Lollipop Ascidian and the Sea Pork.
The area was also alive with the wonderfully named Echinodermata (incl Sea Cucumbers), Annelida (incl Spoon Worms), Cnidaria (incl Sea Anemones), Porifera (incl Hairy Tube Sponge), Bryozoa (incl Lace Coral Bryozoan), Platyhelminthes and Nemertea.
Mayor Logan Howlett said the fresh survey results showed the City’s internationally accredited marina continued to provide a healthy environment where sea life could thrive in a sheltered environment.
“Our marina received an International Clean Marina Accreditation Level 3 through the Marina Industries Association back in 2018 and over the years a wide range of ocean species have paid our marina a visit,” Mayor Howlett said.
“We have regular visits from dolphin and Australian Sea Lions. In past years a Green Turtle, Albacore tuna and even a swordfish have thrilled onlookers.
“While diving, fishing and swimming in the marina is prohibited for safety reasons, due to it being a navigable waterway used by motorised vessels, these surveys are vital to gauge the health of our marina. These tiny critters live in our marina and play an important role in helping keep it clean and healthy.
“Importantly, our marina is also the site of WA’s first Seabin. Installed in January 2019, this floating bin captures all manner of rubbish, including microplastics.”
The monitoring program is the latest in a long-term marine biodiversity series completed by Aqua Research & Monitoring Services (ARMS), which first began sea life surveys at the marina in 2018.
ARMS marine scientists Glen Whisson and Alexandra Hoschke have completed 44 SCUBA surveys at the marina over the past seven years.
The latest included three 90-minute dive surveys across nine hours between February 2023 and 2024 along six 100m routes at various locations inside the marina.
Dr Whisson said a total of 281 photographs were used to verify the species, including two introduced species of molluscs (Dove Snail and Livid Fan Scallop), with neither currently a species of concern in WA, according to advice from Aquatic Pest Biosecurity at the Department of Primary Industries and Regional Development.
Other interesting observations included a pair of nudibranchs which are rarely recorded in WA, and the Blue Button (Cnidaria) which are a sub-tropical species only occasionally seen in southern waters.
Dr Whisson said the data collected over the past seven years was invaluable to gauge the health of the Port Coogee Marina ecosystem.
“We have entered these records onto the
iNaturalist website and they can be found easily by searching under Port Coogee Marina, WA,” Dr Whisson said.
“We know there are many keen divers and snorkellers in the Cockburn area and this kind of data is invaluable when trying to identify the critters they see in local waters.”
Find the three ARMS reports into sea life observations at Port Coogee Marina on the City’s
website.
Images: Orange Mollusc - Short-tailed Ceratosoma brevicaudatum. Blue spotted Mollusc Gem Doris - Dendrodoris krusensternii.
Credit: Aqua Research and Monitoring Services.