For the past 12 months AABio has been surveying the coastal creeks, streams and swamps of the Coffs Harbour City Council’s local government area. The surveys are now complete and the final report has been issued to Coffs Harbour City Council.
The focus of the survey is freshwater crayfish and crustaceans but all aquatic organisms are surveyed and recorded. We were specifically surveying for Tenuibranchiurus crayfish which are a rare and cryptic species in the area. Typically we would catch 150 C. cuspidatus for only one tenuie. We found abundant Cherax cuspidatus and Euastacus dangadi in the region plus numerous other crustaceans. So far we have found five different species of freshwater shrimp. Most species found are common and expected in the area, however we did make some startling discoveries.
We found some unusual species like limpets but of significance was the discovery of an extremely unusual freshwater crab. We were surveying a coastal creek flowing through a suburban Coffs Harbour area and finding long finned eels (Anguilla reinhardtii), intermediate spiny crayfish (Euastacus dangadi), plague minnows(Gambusia holbrooki), empire Gudgeons (Hypseleotris compressa), riffle shrimps (Australatya striolata), glass shrimp (Paratya australiensis), eastern river prawns, (Macrobrachium tolmerum), toebiters (Stenosialis australiensis), which were all common, abundant and expected. What was not expected was finding a freshwater crab! Not just any ordinary freshwater crab but something quite unusual. It’s a first for the ACP we hadn’t found these before. If in doubt I always contact the expert in that particular field. In this case its Peter Davie from the Queensland Museum, he’s the man for crabs and I asked him, “what this!” He advised it’s a River Swimming Crab, Varuna litterata. A marine crab known to occur in freshwater, being excellent swimmers and able to move with the currents along the coast. In Australia they have only been recorded from south east Queensland and north into Northern Australia (Qld Museum). They are also known to occur in India, East Africa and Japan. The discovery of this species this far south greatly increases the known distribution of the species. A specific research projects to acquire new knowledge on this species has been started with The Australian Crayfish Project www.austcray.com Eventually we will submit a scientific paper on the range extension. For an article with more photos, site locations, water quality data, etc. Go to: River Swimming Crab Article. http://www.austcray.com/2014/08/river-swimming-crab-herring-bow-crab-varuna-litterata-2/
Our thanks to Coffs Harbour City Council and specifically to Rachel Binskin, their Biodiversity Officer for their support of the research project and patience awaiting its completion. The project dragged on longer than expected.
Bifenthrin is a pyrethroid insecticide typically applied by pest controllers to protect against termites. It has a high toxicity to aquatic organisms. In July 2012 bifenthrin contaminated Jamison Creek, Wentworth Falls, NSW and caused a mass mortality event of freshwater crayfish and macroinvertebrates. As part of the Australian Crayfish Project we volunteered to conduct a follow up survey of Jamison Creek and similar creeks in the area to monitor the recovery of freshwater crayfish and fish in the creek after this catastrophic event.
Results of those surveys were included in a scientific paper which has been presented at 7th Australian Stream Management Conference held in July at Townsville, Queensland.
St Lawrence, A., Wright, I.A., McCormack, R.B., Day, C., Smith, G. and Crane, B. (2014). Bifenthrin pesticide contamination: impacts and recovery at Jamison Creek, Wentworth Falls, in Vietz, G; Rutherfurd, I.D, and Hughes, R. (editors), Proceedings of the 7th Australian Stream Management Conference. Townsville, Queensland, Pages 558-567.
AbstractIn July 2012, over 1000 dead Giant Spiny Crayfish (Euastacus spinifer) were found in a two kilometre reach of Jamison Creek, Wentworth Falls, including within the Greater Blue Mountains World Heritage Area. A multi-agency investigation discovered the crayfish were killed by a termiticide, Bifenthrin, and that the effects extended beyond the crayfish to the entire aquatic macroinvertebrate community. The contaminant entered the creek via a conventional stormwater drainage system of pits and pipes, which provided a direct connection between the property at which the pesticide was over-applied and the creek 300m away. The pest control operators involved were prosecuted.
Our paper is now available on the conference website:
A new species of Gramastacus freshwater crayfish has been described by Rob McCormack resulting from research over the last eight years as a volunteer on the Australian Crayfish Project (ACP). The eastern swamp crayfish from the genus Gramastacus, was published in the open access journal ZooKeys.
Only one other species of Gramastacus crayfish is known and that occurs some 900 km away in the Grampians region of Victoria. This new species is found in lowland ephemeral habitats between 3 and 48 m a.s.l. surrounding coastal lakes and lagoons from Wamberal Lagoon, north along the coastal strip to Wallis Lake, a straight line distance of 165 km.
This new species “The eastern swamp crayfish Gramastacus lacus” is one of the world’s smallest freshwater crayfish species with specific habitat requirements, preferring ephemeral habitats (smaller creeks, swamps, wet areas and stump holes) that offer conditions that enable their survival and presumably limit threats from other predators, such as eels. Habitats in the same area that consist of permanent water invariably contain large numbers of freshwater eels (Anguilla reinhardtii) and native fish gudgeons (family Eleotridae) but not G. lacus. Many ephemeral swamps and creeks can revert from dry beds to water bodies several metres deep when flooded. Eels and fish may penetrate into and temporarily visit some habitat areas but G. lacus takes refuge in the periphery, protected within the thick reeds and flooded grasses along the shallow edges, well away from the deeper water.
Being dependent on regular natural flooding and drying cycles, only lowland, swampy areas are suitable for this tiny crayfish. Each crayfish digs a small rounded cross-section burrow up to one metre deep into the water table to survive the drying cycle. Some areas are riddled with these small burrows as they are a prolific species and can occur in very high numbers in small habitat areas.
They are found in one of Australia’s, most developed and fastest developing regions, unfortunately, this means that much of their habitat has been lost in the past, these ephemeral areas are the first to be drained or reclaimed to make way for agriculture, industry, housing developments, golf courses and infrastructure, etc. Now, with this species description, this crayfish must be considered in any future developments and hopefully future habitat loss will be reduced.
The scattered populations of Gramastacus seem highly fragmented and many are increasingly threatened by a range of threats other than human development. Invasive crayfish, pest fish species like plague minnows and swordtails, rising sea levels and falling water tables all are increasing threats. Luckily, the large number of National Parks and Reserves along the coastal strip provides safe refuges for some populations.
“The eastern swamp crayfish Gramastacus lacus sp. n. (Decapoda, Parastacidae) a new species of freshwater crayfish from coastal New South Wales, Australia” was published in Issue 398 of ZooKeys. This is a free access journal and if you would like a copy of the paper in full go to: http://www.pensoft.net/journals/zookeys/article/7544/abstract/the-eastern-swamp-crayfish-gramastacus-lacus-sp-n-decapoda-parastacidae-a-new-species-of-freshwater-crayfish-from-coasta
This post relates to some photos Chris from Queensland sent me. They are of his Cherax depressus which he found in the Noosa area. He caught the pair after a heavy rain event and took them home to his aquarium. The area they were captured is usually dry so they only come out of their deep burrows and get active when there is water around.
This is what Chris said:
“These two Yabbies are very polite and well behaved, they were very cautious in the aquarium at first. I put a red LED floodlight on the tank at night, just to see what they got up to, and found that almost every night these two yabbies would be side by side “dancing” – it was the female trying to instigate mating. The male wouldn’t perform so he was isolated for a few days. Two days after putting the male and female back in the same tank she was berried.”
“The babies began dropping from the mother on about the 10th of Jan, 2014. I kept the mother in a Guppy breeding tank for a few days to separate the babies from the mum, on the assumption that the mother would eat the babies. After three or four days I realised that the babies were safe so I put the babies in with their mum in a separate tank. Almost all of the babies reattached themselves to the mum. After two weeks the mother and babies are still living together, she ignores her young as they climb on her claws and eyes and get piggybacks during feeding time, but they very rarely go to the tail anymore. The mother has shed her shell and simply appears to be happy, surrounded by her offspring.”
Cherax crayfish make great aquarium pets and they occur throughout most of Queensland. But make sure you are catching Cherax and not Euastacus. Please remember, all Euastacus freshwater crayfish are protected in Queensland under the Fisheries Act 1994 and Fisheries Regulation 2008, regardless of size. The catching or possession of these crayfish is totally prohibited so you cannot keep small ones as pets.
I’ll do an article on how to tell the difference between Cherax and Euastacus for those of you that don’t know the difference, so stay tuned.
False spider crabs Amarinus lacustris are a widespread and relatively abundant small crab species inhabiting low salinity and freshwaters waters in south eastern and eastern Australia, New Zealand, and Lord Howe and Norfolk Islands. They are a small freshwater crab species only reaching 10 mm in body width, with a distinctive H-shaped groove on their back. They are a slow growing species that can be covered with weeds or algae growing on their shell which makes them harder to see and for predators to find. It’s a small vulnerable species that is cryptic in nature and rarely seen or captured, spending most of their life hiding in thick reeds and roots or under rocks that offer protection and shelter from predators. Though widespread and when present they can be abundant (the ACP has found them at over 100/m2) they are a cryptic species that makes finding them difficult. The knowledge base on this species is relatively small, additionally, little has been done on the taxonomy and genetics of this widespread crab species and it is currently proposed that the current description may in fact represent three or more distinct species.
The ACP is intensifying research on this species and continues to collect specimens from across Australia. As we collect more specimens we are getting to know their habitat preferences and it’s becoming easier and easier to find these elusive creatures.