The Occurrence of the Venus shell, Tapes literatus, in the Port River

October 13, 2018 | Posted in: Climate change, Invasive species, Marine invertebrates, Molluscs

Last year, I found a Venus shell, Tapes literatus at the Ships’ Graveyard in the North Arm of the Port River. I reported the discovery in my article entitled Further Discoveries at the Ships’ Graveyard.

More recently, two more specimens were found on the western side of Torrens Island (8 October 2018).

My kayak partner (known only as Greg) picked up a live specimen he spotted whilst we were motionless in shallow water. He passed it to me for inspection, after which I released it back into the water.

 

Greg standing in the foreground

A little while later, Greg picked up a dead specimen which I asked him if I could keep. I was only able to throw it in to the bottom of our tandem kayak at the time.

The western side of Torrens Island

To keep a long story short, we managed to safely return to our cars at Snowden’s Beach with our collected specimen. I had to leave in a hurry, so I tossed the specimen in the boot of my car.

The specimen remained on the floor of my carport until today, when I finally got around to checking it out more closely. I confirmed that it was a Venus shell, Tapes literatus. I sent a text message off to to Peter Hunt from the Malacological Society of SA to notify him of the discovery.

In Further Discoveries at the Ships’ Graveyard last year, Peter commented that the shell was “definitely the common and wide spread tropical species Tapes literatus (Veneridae)” and that it was not native to South Australia. He advised that the numbers of them in the Port River and their level of invasiveness were unknown. He also wrote:

“If a colony does exist I expect that a colony will only be competing for a limited habitat space at this point (with displacement of other sand dwelling bivalves likely). Other implications of their existence should be researched earlier rather than later, more hastily if we can confirm a population existence with more finds. If my ID is confirmed, then this common species and other similar species are all well documented and can easily be researched.”

We provided the 2017 specimen (shown above) to the
South Australian Museum for their shell collection

I sent these two photos of my latest discovery (2018) off to Peter Hunt: –

The photo on the left featured two coins for size comparison. The photo on the right showed that the shell was slightly over 50mm wide.

Peter Hunt wanted to know the location of the two specimens that I had seen on this recent kayak trip, but I couldn’t answer precisely. I could only suggest that the two were found in a general area north of the North Arm, north of the power station, about a quarter of the way towards the old Quarantine Station on Torrens Island.

Peter made some further comments, advocating further collection and study.

“This is a very variable species, attracting many synonyms around the country. It may assist in tracing history, but everything suggests that it has come from the east… We should look for more as there may be lots now. This is larger than my find, so can only assume they are thriving.”

My sightings of the 2017 and 2018 specimens have both been posted on iNaturalist:

We agreed that more live and dead specimens should be collected, but acknowledged that the live collection ban enacted last summer to prevent the spread of Pacific Oyster Mortality Syndrome (POMS) could prevent our studies from progressing in the near term.

PIRSA’s website states that the blanket ban on the collecting of shellfish from the Port River remains in force, and provides clear reasoning. It states that “the taking of all bivalve shellfish (including oysters, mussels, cockles, razorfish) is not permitted from the Port River until further notice. The ban has been implemented to reduce the risk of spreading the Pacific Oyster Mortality Syndrome (POMS) virus that has been detected in feral Pacific Oysters in the Port River.”

Map of Port River bivalve closure (PDF 272.5 KB).

Furthermore, collection of bivalves is prohibited in all waters of West Lakes and Port Adelaide River between Bower Road, Semaphore Park and the junction of Lipson Reach and North Arm, Port Adelaide.

Once the ban is lifted, or a special exemption is granted to us, we intend to collect further specimens for future study.

Steve Reynolds is the current President of MLSSA and is a long-standing member of the Society. Steve is a keen diver, underwater explorer, photographer and is chief author of the Society's extensive back catalogue of newsletters and journals.

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