In 2017 the Hunter Region of NSW was suffering from the worst drought in 50 years. In late 2017 my local creek at Port Stephens dried up for the first time in the last 18 years since I’ve been here.
As the water dried out, I took the opportunity to investigate all the species that occur in my creek. The shallows of the creek dried rapidly but the deeper pools retained water through most of the 2017 period.
Interestingly, I observed freshwater mussels moving from the shallows into the deeper water. They use their foot which is tongue like to push themselves along. This leaves a trail in the sediments which you can easily follow to the mussel.
I was quite surprised by the sheer number of them that were in my deeper pool that I would normally use as a fishing and swimming hole. Typically its over 3 metres deep but the drought saw it shallowing to less that 300mm. Freshwater mussels are great indicators of your streams health. They are sensitive to pollution and sedimentation so if you have healthy populations, your stream is more than likely healthy.
The water in the bottom of my pool was clear, warm and shallow so I decided to survey the freshwater mussels in it. I systematically, worked my way by hand through the bottom sediments, feeling for mussels and counting them.
Interestingly, I found around 2600 mussels in the pool. That’s great news and indicates my creek is generally health and has been so for quite some time. Mussels are very long lived 20-40 years and these were a good mix of small to large old mussels that I was finding, indicating healthy conditions for many years.
Unfortunately, I’m not a freshwater mussel expert but I have spent some time over the years with experts helping them collect mussels for identification. The mussels I found were all very similar in size, colour and shape. However, if you looked closely, occasionally, I would find something different.
The most common and abundant freshwater mussel was Hyridella drapeta.
Interestingly, in amongst the 2600 mussels were around 160 different ones, these were Hyridella australis.
They look very similar but if you look closely they have v-shaped sculpturing on the beaks of the shells.
Freshwater mussels are natural biofilters processing large volumes of water. They remove large quantities of nutrients, algae, bacteria and organic matter which helps to clean water bodies. Both H. australis and H. drapeta are classed as river mussels. They need permanent and flowing water to breed and survive so generally found in permanent flowing streams.
Many people want freshwater mussels for their fish ponds or farm dams to help keep them clean. River mussels are not suitable and will eventually die in a static water dam or pond. However, there is one species that thrives in static water dams and ponds. That’s the flood plain mussel Velesunio ambiguus. This mussel will live and breed up to huge numbers in your ponds and helps to keep your water clean. This is a commercially, cultured species so available for purchase from aquaculture farms like AustSilvers or if you just want one or two for a fish tank then check with your local aquarium shop.
BTW, If you want to start a sustainable population going in a farm dam you will need several hundred as initial stock.
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.
An Expedition into “The Myall Lakes National Park” – Gramastacus crayfish and Amphipods – and watching the dingo on my back trail!
I was surveying freshwater crayfish in the Myall National Park the other day and spent the day hiking by myself up the old Hawks Nest Seals Rocks Road and surveying the surrounding swamps. 20 years ago I used to drive this road and it was potholed then. Now it’s all a National Park and closed to vehicles and heavily overgrown in sections and still quite good in other sections. I think it’s an old mining road that is a raised, rocky road through the centre of the Myall swamps. Either side on the road is wet swampy areas that are impenetrable, reeds, saw grass, tee trees, paperbarks and swamp banksias, etc.
The procedure was to hike along the road and stop every kilometre or so, put on my waders and wander into the swamp to sample the aquatic fauna. I’d stop on the road, drop my pack, take off my hiking boots and put on my waders, grab my scoop net and bash my way through the scrub and scoop the underlying swamps. At the second site about 2 km in I noticed a large dingo about 50 metres up the track watching me. For the next several hours this large dingo just kept following me along the road always staying 50-100 m back. The track was alive with other life, mostly birds, the odd lace monitor and occasional snake. At the 7 km mark the dingo was still there and again I put on the waders, bashed about 6 mtrs off the road into the wetland and scooped the shallow water. All up less than 5 minutes scooping then back to the road to sort the catch, I would see what I had then take the tadpoles and macro inverts back and release them. As I climbed back onto the old road I looked back for my dingo and couldn’t see him, not a worry as he was a sneaky critter and liked to hide just peeping out to watch me. Anyway, I sat down on the road to sort the catch and glanced up the road in the direction I was heading and with a start there was my mate the dingo. The sneaky critter had passed me within 7 mtrs and I never saw or heard anything. It was a relief to have him in front as hiking along and watching my back trail was a hassle. For the next kilometre I followed him, then he disappeared and just before the 9km mark I saw him way in the distance heading north.
The crayfish were restricted to the smaller pools that still retained water as the swamps were drying out. Many of the Gramastacus crayfish were in berry. They are a small species and females with eggs weigh in at only 1.73 grams.
Much of the Myall freshwater swamps have large sphagnum moss areas and I was scooping the sphagnum looking for the freshwater crayfish that hide in it and was surprised by the large number of amphipods that were also hiding in the moss. Most of the larger female amphipods were also in berry with the eggs tucked up under the carapace between their legs. I don’t know the genus but they had very large gnathopods and very spiny legs. Perhaps sometime in the future I will identify the species. If anyone knows amphipods and can identify them please let me know.
Aquatic Biodiversity Survey and Baseline Mapping of Freshwater Crayfish and Aquatic Species of the Gosford Local Government Area
As Part of the Australian Crayfish Project and a sub project 100056 we have been conducting aquatic biological surveys the whole of the Gosford LGA. This project is major sponsored by Australian Aquatic Biological and receives sponsorship from Gosford City Council under their Ecological Research Grants scheme 2010. The project reached fruition in May 2012 with a total of ten aquatic biological catchments reports being issued to Gosford City Council.
The biological surveys were undertaken as part of both the broad Australian Crayfish Project (ACP) and Australian Aquatic Biological Survey (AABS) and a targeted sub-project on the Gosford LGA, Project 100056, Australian Aquatic Biological 2010.
Surveys of the Gosford LGA are completed on a catchment/drainage basis and a total of ten catchment areas were independently surveyed.
1 Wamberal Lagoon
2 Terrigal Lagoon
3 Avoca Lagoon
4 Cockrone Lagoon and Surrounds
5 Green Point to Kilcare & Bouddi NP – Coastal Streams
6 Erina Creek
7 Narara Creek 100056-7 Completed 67, 77, 78, 86, 87.
8 Point Clare to Mullet Creek
9 Mooney Mooney Creek
10 Mangrove Creek to Wisemans Ferry
This was a two year project that discovered much new information The primary aim of Project No. 100056 is to determine what freshwater crayfish occur where in the Gosford LGA. Primarily freshwater crayfish are the priority and the Gosford LGA represents a significant area for crayfish distributions, yet little is known on the distributions of crayfish in this area. Prior to the start of this research project only two species have recorded distributions within the LGA (Euastacus australasiensis and Euastacus spinifer) yet the extent of their distribution are unknown. Additionally, the area includes a number of coastal lagoons, lakes and streams all with independent catchments draining directly to the Tasman Sea that have been isolated from each other for millions of years and many containing unrecorded crayfish species.
The project also records information on all the other aquatic fauna found in the LGA as well as information on landforms and vegetation. All this is in order to facilitate the better conservation and management of the aquatic ecosystems of the Gosford LGA.
Note: For environmental and hygiene reasons (transfer of pests, diseases and weeds, etc.) each of the catchments are treated as individual systems and are surveyed separately with equipment and personnel being sterilized between catchments. A copy of our Hygiene Protocol and Code of Practice is available online at www.aabio.com.au
We managed to map the distributions of four freshwater crayfish species that occur in the Gosford LGA. Euastacus australasiensis, Euastacus spinifer, Cherax destructor and Gramastacus sp.