Australian Aquatic Biological

Australian aquatic biodiversity research and consultancy

Central Highlands Burrowing Cray Engaeus affinis (Smith & Schuster 1913)

Engaeus affinis from a communal burrow, Healesville, Vic

Engaeus affinis from a communal burrow, Healesville, Vic

This species is endemic to Victoria with a relatively small distribution known at this time (estimated extent of occurrence of approximately 200 km2). Found in the upper Yarra, Acheron, Yea and Big Rivers. An area roughly from Kinglake to Eildon to Jamieson to Noojee to Hoddles Creek. Central Highlands Burrowing Cray Engaeus affinis has been assessed on the IUCN Red List as Data Deficient. 

Engaeus affinis, Healesville, Vic

Engaeus affinis, Healesville, Vic

It’s a robust species and at many sites relatively abundant. Typically, it’s a communal burrower, both type 2 & 3 burrows with multiple surface entrances (20 or so) over a square metre. Both fans shaped entrances and chimneys. Surface openings descend into large central burrows. Central burrows are relatively large in diameter (150 to 200 mm), typically water filled and tending horizontal and descending and converging into a larger chamber.

Engaeus affinis, Badger Creek, Vic

Engaeus affinis, Badger Creek, Vic

Typically, the easiest way to capture is to excavate down to the water level, usually from 200 to 600 mm deep. Once water is found, wait, (patience required), larger males will come to investigate the disturbance and you can grab them, otherwise, every 5 minutes or so, shove your hand down the burrow and feel around in the water. If you are lucky and have good feeling in your fingers you should be able to grab one every 5-10 minutes. That’s the way we collected the specimens for this article.

Burrow entrance, Badger Creek, Vic

Burrow entrance, Badger Creek, Vic

Those from Healesville were in a yellow clay on the slope beside a creek approximately 1.2 metres above the creek water height (7 metres from creek bank) but had water at 650 mm in the burrow system. Those from Badger Creek were in a fine silty material in a seepage area in the tree fern forest with water only 100 mm below ground level and over 100 m from Badger Creek.

Engaeus affinis, Badger Creek, Vic

Engaeus affinis, Badger Creek, Vic

Happy Yabbying

Cheers

Rob

Lowland Burrowing Crayfish Engaeus quadrimanus

Also known as “The Mernda Land Yabby” Engaeus quadrimanus (Clark 1936) is a relatively widespread and locally abundant species. It’s a lowland species generally found under 250 m a.s.l. from just north of Melbourne, east along the Victorian coast to just before the NSW border. Engaeus quadrimanus has been assessed as Least Concern on the IUCN Red List.

Engaeus quadrimanus - note the burrow entrance behind

Engaeus quadrimanus – note the burrow entrance behind

This specimen is from the west of the range. Collected from the bank of Fish Creek a tributary of the Tarwin River crossing Meeniyan-Promontory Rd, Fish Creek, Victoria.

A very robust and adaptable species that usually has large colonies with the area being riddled with burrows. Typically, burrows are round to oval in shape and open with excavated material at the entrance (see photo). In some areas they can create a pelleted chimney but for many areas it’s just an open hole in the ground as the excavated material has been washed away with flood waters. Burrows are type 2 and relatively basic with only 2-3 surface entrances descending to a horizontal corridor then a deeper burrow to water table. Typically most of the burrow system is flooded and typically they are individual burrows with both males and females having their own burrows. One of the keys to the species is that they are intersexed so hard to determine which are males and which females. Breeding season is autumn and they can be found sharing burrows together then. The species is extremely active during flood events and uses the creeks to migrate and find mates, etc.

Fish Creek

Fish Creek

For a similar article on this species and images from populations further east, go to: http://www.austcray.com/2015/09/engaeus-quadrimanus-from-cann-river-victoria/

Cheers
Rob

 

Orbost Spiny Crayfish paper finally published

Euastacus diversus from Ellery Creek (Brodribb drainage) showing 2 marginal squamal spines

Euastacus diversus from Ellery Creek (Brodribb drainage) showing 2 marginal squamal spines

Started in 2005 the quest to rediscover the Orbost Spiny Crayfish Euastacus diversus has been a long and intriguing journey cumulating in the publication of this paper.

This story began back in 1959 when one of Australia’s foremost expert on freshwater crayfish at that time, Edgar Riek, discovered this small freshwater crayfish species in the east Gippsland region of Victoria. Then in 1969 he described the species and named it Euastacus diversus. Since that day this crayfish has remained a rare and elusive species.

In 1986, the then current expert on the genus Euastacus, Gary Morgan, searched for this species but was unable to find any in the wild. As a consequence he redescribed the handful of original specimens collected by Riek in 1959 that are held at the Australian Museum. Gary Morgan’s detailed description, published in the Memoirs of the Museum of Victoria 30th May 1986, was the latest scientific publication on this species and forms the basis of all current information and opinions until now.

In 2005, the Australian Crayfish Project (ACP) was started, involving one of the largest projects researching freshwater crayfish ever seen in Australia. Between 2005 and 2007 we also failed to find any specimens of Euastacus diversus for the type locality general area 40 miles north of Orbost. Then in 2007 we changed our methods and successfully started finding more and more specimens. Up to 2011 a considerable number of E. diversus and other Euastacus species were found in the wild. The project has been very successful in finding this and other crayfish species, and large areas of southern NSW and eastern Victoria were systematically biologically surveyed specifically for freshwater crayfish. We found Euastacus specimens everywhere and most did not match the description for the known species leading to much confusion. However, genetic analysis by the Carnegie Museum of Natural History in the USA helped clarify the situation resulting in the thorough redescription of E. diversus and the discover of a number of new species.

Euastacus diversus redescription 2015

Euastacus diversus redescription 2015

The research culminated in this paper titled “Re-description of the Orbost Spiny Crayfish, Euastacus diversus Riek 1969 (Decapoda: Parastacidae), in Eastern Victoria, Australia” published in the journal “Freshwater Crayfish”. The paper redescribes Euastacus diversus to include the Bonang River crayfish (previously thought to be a new species).

The Bonang River crayfish from the most northern extent of distribution

The Bonang River crayfish from the most northern extent of distribution

The Bonang taxon represent a morphologically distinct population of Euastacus diversus that is genetically 1.95% divergent from the E. diversus type locality populations.

Euastacus diversus from Riddle Creek

Euastacus diversus from Riddle Creek

The research extends the distribution of the species to the Brodribb, Yalmy, Rodger and Bonang River drainages at elevations ranging from 350 – 950 m a.s.l., with an overall Extent of Occurrence of 465 km2. Research continues on E. diversus which will surely increase the Extent of Occurrence. Research also continues on the new Euastacus species and hopefully the first of the new species descriptions will be published later this year.

Citation:

Coughran J, McCormack RB and Fetzner Jr. JW (2015). Re-description of the Orbost spiny crayfish, Euastacus diversus Riek 1969 (Decapoda: Parastacidae), in eastern Victoria, Australia. Freshwater Crayfish 21(1): 185-197.

 

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Aquatic Biodiversity Survey of Coffs Harbour coastal region completed

Aquatic Biodiversity Survey Coffs Harbour Region

Aquatic Biodiversity Survey Coffs Harbour Region

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.

Cherax cuspidatus

Cherax cuspidatus

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.

Euastacus dangadi

Euastacus dangadi

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/

The Freshwater River Swimming Crab Varuna litterata

The Freshwater River Swimming Crab Varuna litterata

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.

The Southern Lobster Euastacus yanga

The Southern Lobster

The Southern Lobster
Euastacus yanga

We have finally finished our aquatic surveys of the lower Clyde River, NSW. It’s an exciting area with mostly pristine clear flowing streams full of aquatic life. The results of the survey have been extremely interesting and have resulted in some significant findings. We have identified 3 different freshwater crayfish species in the lower Clyde River and they all match the known descriptions for all three species. Interestingly, the specimens of Euastacus crayfish previously collected from the upper Clyde are generally morphologically different to those in the lower Clyde. Eventually we will get the genetics done on all the specimens collected and then work out whether the upper Clyde specimens are a morphological variation or a separate species. Stay tuned for further updates. The full results of the aquatic biological surveys will be complied into a report and issued to the Southern Rivers Catchment Management Authority.

The Lower Clyde River NSW

The Lower Clyde River NSW

We surveyed 57 sites and at 43 of those we captured freshwater crayfish. A total of 149 Euastacus yanga were captured, examined, weighed, measured, and released during this survey. Euastacus yanga has the third largest distribution of any Euastacus species in Australia after E. spinifer and E. armatus. Found in south-eastern New South Wales from Robertson all the way south to north-eastern Victoria. It’s distribution extends from the Shoalhaven River in the north, then south through the Clyde, Deua, Tuross, Brogo, Murrah, Bega, Towamba, Womboyn, Wallagaraugh and Genoa rivers, as well as all the smaller coastal rivers and creeks running into all the inlets, lakes and bays down the coast. Found from 50 m to 895 m a.s.l it is a widespread and abundant species.

Berried female Euastacus yanga in a small clear feeder stream

Berried female Euastacus yanga in a small clear feeder streams

We observed Euastacus yanga to commence breeding in mid May in water temperatures between 11.3-12.1°C. The berried females nurtured their eggs and young till mid November to mid December when they released their brood into the streams. A huge amount of information was gathered as part of the surveys and this will be compiled into a peer reviewed scientific manuscript.

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