Walkers along the Torrens banks between May Tce and Henley Beach Road in the past few days may have seen a number of dead or dying fish, particularly carp and possibly catfish. This is the EPA’s prompt response to our enquiry today:
We had a look at this and it appears that the recent rains have added a large organic load to the lowland Torrens River which, along with an obvious algal bloom, have resulted in the water holding minimal dissolved oxygen to sustain the many large carp and catfish you probably saw on your walk. While the current warm, sunny weather continues it is likely that more fish will continue to die. I would however expect the smaller fish to persist because they can usually get enough oxygen from gasping in the shallows, compared to larger fish that are more susceptible to these sorts of events. Council will be putting up signs and removing as many of the accessible fish as possible. Finally, these sorts of events happen occasionally in many lowland streams during the year, so it is not that unexpected for the bottom of the Torrens – and has occurred in the past through the same section of river.
To explain this further here is a paragraph from a 1988 EPA report: Dissolved oxygen (DO) is important for most aquatic organisms and varies with temperature, salinity, rainfall and runoff containing oxygen demanding organic material. Concentrations in unpolluted waters are generally between 7 and 10 mg/L. DO concentrations vary seasonally or even daily in response to temperature and biological activity. DO is used to indicate the degree of pollution caused by organic matter. DO concentrations below 5 mg/L are stressful to most aquatic animals.
Ambient Water Quality Monitoring of South Australia’s Rivers and Streams (Chemical and Physical Quality) EPA Water Quality Monitoring Report No 1, 1998
And another explanation of the impact of low dissolved oxygen, from a US website: Natural conditions such as high temperatures, large amounts of leaves and woody debris that fall into the river from streamside forests and an absence of waterfalls or riffles to aerate the water can lower DO concentrations. Nitrogen and phosphorus (N & P) added to rivers from point sources such as waste water treatment facilities or nonpoint sources such as runoff from agricultural or urban areas may enhance the growth of algae in streams and rivers. As algae complete their life cycle and die, they become a food source for bacteria which consume oxygen as they decompose the algae. Large populations of bacteria feeding on algae are able to consume all the oxygen available in water – thus leading to the death of other aquatic organisms, including fish, which depend on the DO. This is often described as a fish kill in the popular media. http://www.nespal.org/dissolved%20oxygen.html
posted by Angela Gackle on 17/5/2014
You are invited to join us on Wednesday 27th November 2013 – starting at 5pm for drinks and nibbles!
The venue is the Henley Sailing Club, 1 Seaview Road, West Beach
We have two guest speakers:
Tim Kelly, Outgoing Chief Executive, Conservation Council SA – Infrastructure, Development and South Australia’s Gulfs
Sam Gaylard, Principal Water Quality Officer, EPA SA – Aquatic Ecosystem Condition Reporting
RSVP for catering please to Liz McLeay:
by phone: 8332 9324
or email: firstname.lastname@example.org
A very successful Open Day was held at the Tennyson Dunes on September 15th. More than 100 people attended, together with Ian Hunter, Minister for the Environment and Sustainability, Shadow Minister Michelle Lensink and Stephen Mullighan, Labour candidate for the seat of Lee.
Professor Chris Daniels and Associate Professor Victor Gostin gave talks to groups of visitors, who were given tours of the dunes by members of the Tennyson Dunes Group.
The Tennyson Dunes Group was invited to a meeting with the Minister for The Environment and Sustainability the following week, where they were informed that the Minister has decided to declare Tennyson Dunes a Conservation Reserve, provided that the wider local community were supportive. A meeting will be held to gauge public opinion and a petition will be sent to local householders.
The return of warmer weather in recent weeks has lured many Adelaideans back to the coast – ready to embrace the beach culture that we so love in summer. If you were among the walkers or swimmers, perhaps you too have been appalled by the colour of the water – a huge unappealing brown slug hugging our favourite beaches.
The cause is a cocktail of silt and other pollutants that has been pouring out of the creeks and many stormwater drains that empty onto the coast for decades. The incoming and outgoing tides mix and spread this pollution – but only a bit. Water in Gulf St Vincent does not move extensively – it basically sloshes in and out (up and down the Gulf), so the pollution radiates slowly away from its source.
In still conditions, the silt settles out, and water quality can be pretty clear. When windy weather hits, the silt is remobilised – stirred up – and the water becomes brown once again.
Depressingly, this layer of gunge is now a permanent feature of the Adelaide metropolitan coast.
But the story is more complicated…
Below is the latest update from the Department for the Environment, Water and Natural Resources on the dead dolphins and morbillivirus.
Dolphin deaths – frequently asked questions
Date posted: 30 April 2013
What is the current situation with dolphin mortalities?
Test results and observations made during the post mortem examinations point strongly to dolphin deaths having been caused by an outbreak of dolphin morbillivirus.
What is dolphin morbillivirus?
Dolphin morbillivirus is one of a family of viruses that includes distemper in dogs and measles in humans. In dolphins, it is known to cause brain and lung infections and suppress immunity, leading to secondary infections. It has been found previously in overseas dolphin populations and in Queensland and Western Australia.
How is it transmitted?
Dolphin morbillivirus is transmitted by close contact between dolphins, including between mothers and newborns. It cannot be transmitted to humans. It is unlikely that the disease would be able to survive in the environment, outside an animal, for any significant length of time.
How many dead dolphins have been found?
Thirty-one dolphins have been found along the South Australian coast since 1 March. Twenty-six of these have been found in the Gulf St Vincent bioregion, three in Spencer Gulf and two in the South East. The most recent finds were juvenile dolphins at Port Broughton on 27 April and O’Sullivans Beach on 28 April.
Where have dead dolphins been found?
Dolphins have been found at Middleton, Maslin Beach, Seacliff, Sellicks Beach, O’Sullivans Beach, Grange, Port Noarlunga, Hallett Cove, Outer Harbor, North Haven, West Beach and the Port River, at Stansbury, Port Julia and Port Broughton on Yorke Peninsula, Danger Point and Canunda in the South East and at Brownlow Beach, Kingscote and Strawbridge Point on Kangaroo Island.
What do we know about the dead dolphins?
Most of the dolphins that have been identified are Indo-Pacific bottlenose dolphins , although at least two are short-beaked common dolphins. The age of the dolphins ranges from birth to young adult.
What has been found in the dead dolphins?
Sixteen dolphins have been examined to date. Five have tested positive for dolphin morbillivirus, including two examined by the University of Adelaide’s Veterinary School. Some results of laboratory examinations are still pending Many of the animals have pneumonia associated with parasite burdens (lung worm) and disseminated fungal infections. This suggests the animals have been stressed and may have had impaired immune systems at the time of death. This is characteristic of viral diseases.
Why haven’t all the dolphins been examined?
The inter-agency team looking into the dolphin deaths has concentrated on the carcasses found in Gulf St Vincent, as this is where the highest concentration of deaths has occurred. The dolphins recovered in the South East and in Spencer Gulf will be examined at a later date.
Five of the dolphins reported dead could not be recovered and therefore could not be examined.
What about the dolphin calf from the Port River?
Mimo, the Port River dolphin calf, was collected on 16 March. His behaviour appeared to be abnormal from birth, so his death may well have been unrelated to those of the others. The pathology results from his post mortem examination have not yet been received.
If you think the deaths are caused by morbillivirus, why have so few dolphins tested positive?
Not all of the dead dolphins were able to be tested for viruses because the carcasses were too decomposed. The others do show signs that are consistent with the secondary infections common in dolphins suffering from morbillivirus.
Are the dolphin deaths linked to the fish deaths?
The recent fish deaths have been linked to an algal bloom. We do not fully understand the predisposing causes of morbillivirus infection in dolphins, but the outbreak may be linked to the same warmer-than-usual water temperatures that caused the bloom.
Are dolphins dying because of the desalination plant?
Nothing surrounding the deaths of the dolphins points to any link to the desalination plant. Salinity levels in the gulf are not at a level that would be considered dangerous. Also, dead dolphins have been found well away from the desalination plant, where salinity levels are absolutely normal.
What tests are being carried out and where have samples been sent?
Most of the dolphins that have been recovered have been examined at the South Australian Museum by a collaborative group of pathologists, veterinarians and biologists. The dolphins examined at the museum are photographed and measured, then undergo a full post-mortem. Many samples are collected, including liver, kidney, brain, muscle, heart, blubber, stomach contents and urine. The samples collected for pathology will be studied immediately using a variety of tests such as histology, bacteriology and toxicology.
Other samples will be available for future studies if the need arises. In addition, all the bodies will be macerated and the skeletons examined in detail at a later date.
PIRSA is supporting the South Australian Museum and DEWNR with the dolphin mortalities, with the Chief Veterinary Officer assisting with port mortems and pathology diagnostics.
The University of Adelaide has also examined two dolphins. Tissue samples from these and from the South Australian Museum cases have been forwarded to the Australian Animal Health Laboratory at Geelong for virus studies.
Why are the results taking so long?
Most of these tests are undertaken in Australia but the toxicity tests are to be undertaken in New Zealand. Therefore it takes a significant amount of time to get full sets of results back.
What results have been received?
Laboratory testing has identified dolphin morbillivirus in tissues from five animals, and changes consistent with a virus infection were also seen in some tissues.
Tests for algal toxins in the dolphins were negative. Microscopic examination of tissues has been completed on some dolphins and the findings indicated that the animals had pneumonia. Some also had inflammation of the brain (encephalitis). Fungi were identified in some of the affected tissues.
When will more results be available?
Post mortems are still being undertaken, so the results will come in gradually over the next three or four weeks.
Surely this isn’t a normal situation?
The numbers of dead dolphins we have seen in the Gulf St Vincent bioregion is an unusual occurrence, which is why comprehensive testing is required to determine what is actually happening. This is the first time dolphin morbillivirus has been seen in South Australia.
Is this mortality event going to impact on dolphin populations?
At this stage it does not seem that the number of dead dolphins will impact the population of bottlenose dolphins living in the bioregion.
There is no precise number of how many dolphins live in the Gulf St Vincent region but it may be as many as a few thousand. Natural mortality of dolphins occurs regularly. However, the current observed dolphin mortalities are unusual. The Indo-Pacific bottlenose dolphin is protected by law but it is not a threatened species.
Did you hear about the extremely rare magpie fiddler ray Trygonorrhina melaleuca caught by fishermen in the Port River last week? There is a nice item about it on the ABC website (see link below), including an interview SARDI researcher Paul Rogers who is making some observations on the ray before releasing it back into the Port River at the request of the anglers who caught her.
This story is significant for many reasons.
1. This is a ray that has only ever been seen a few times before, and yet still exists – in the Port River – and we know so little about it!
2. It reminds us that there are many species that are unknown or not well understood, and that opportunities to learn more about them are valuable.
3. The anglers who caught the ray (from the Adelaide Game Fishers Club) recognised that they had caught something special, contacted SARDI and have requested that the ray be released back into the river.
4. It adds weight to the argument for protection of biodiversity in the Port River, which clearly supports some interesting species, despite being a busy industrial area.
Regular beach walkers will have seen the unusually high numbers of some fish species that were washed ashore before and around Easter.
If you were really unlucky you might also have seen one of the many dolphins washed up in the past month or so.
Friends member and marine champion Scoresby Shepherd discussed the massive kill with SARDI authority Marty Deveney in late March.
He noted that the species washed ashore are all poor swimmers, and that CSIRO has advised that sea temperatures along the coast have been up to 5 C warmer than the previous hottest temperatures recorded, with uniform temperatures throughout the water column.
Poor swimmers are unable to swim off to other waters or to surface waters. The role of the gale was merely to wash them ashore from over a wide area.
In other words this is an unprecedented marine heat wave similar to that on the WA west coast 3 years ago. The grimmer conclusion is that this is an extreme event that augurs the future for southern waters.
PIRSA issued the following statement last week:
FISH MORTALITIES UPDATE: No.1 – 5 April 2013.
You would be aware of the recent reports of fish kills and dolphin deaths in SA waters. The reports of fish deaths have extended across both gulfs since the start of March. While the suspected cause of the fish deaths is increased warm temperatures due to the recent, prolonged hot weather in South Australia together with reduced oxygen levels in water caused by algal blooms, the cause of the dolphin deaths is still being investigated.
On Wednesday, Minister Gail Gago released a statement announcing the appointment of a specialist cross agency team of senior officers from DEWNR, PIRSA, EPA and SA Water which will review all of the available information to see whether there is an adequate explanation. The team is led by myself. At this point in time, the available evidence is indicating that the likely explanation for the fish kill is an algal bloom linked to warm gulf waters and nutrient upwelling. This is supported by the preliminary investigations and analysis of water quality and fish mortality.
The EPA has ruled out any link with the desalination plant – the water quality parameters are well within prescribed limits. The fish kills under investigation extend across both gulfs (as far as Dutton Bay, north of Coffin Bay, and Port Neill also on Eyre Peninsula) and the South East.
To ensure that interested stakeholders are kept fully informed on this issue, we have established an email network where we will keep people informed of the progress of our investigations. We have also established a website at www.pir.sa.gov.au/fishmortalities where we will be posting updates and information, including FAQs, media releases and backgrounding about this matter. Progress reports will be published as we proceed.
Any fish or other marine life mortalities can be reported by phoning FISHWATCH on 1800 065 522.
Please feel free to send this email on to interested colleagues.
Chief Executive, Primary Industries and Regions SA
MODIS satellite image of the gulfs in early March
What about the Dolphins?
(text below based on news item from Adelaide Now 4/4/2013 and an ABC 891 radio interview on 3/4/2013)
Senior researcher and curator of mammals at the South Australian Museum, Dr Catherine Kemper said early results from the first dolphin autopsy had provided no clear answers, but revealed one possible cause.
Around 17 reports of dolphin carcases washing up on South Australian coasts have been reported in the past month.
It is the largest spike of reported deaths of marine mammals locally for a long time.
Dr Kemper said the last large spike in dolphin deaths was the result of shootings, with five reported deaths in the late 90s.
She said whilst it was not possible to draw conclusions from a single autopsy, traces of E. coli found around the animal’s blow hole and abnormal organ sizes were of concern.
With the amount of sealife washing up on local beaches recently, Dr Kemper said it may be possible, as has happened in other areas around the world, that biological toxins may be responsible for the deaths.
“This happens when you have red tides, algal blooms and dinoflagellates. The bacteria are digested by smaller fish and work their way through the food chain. We wouldn’t normally do testing for this, but we will this time.”
Whale and Dolphin Conservation Society science and education manager Dr Mike Bossley urged the State Government to set up a cross-departmental taskforce to investigate.
He said there was not enough co-operation between those investigating dolphin deaths, algal blooms and washed-up fish.
Dr Bossley said the cost to perform tests – particularly for dolphins – also was a problem.
“I’m concerned for two reasons – one is that the (deaths) are quite high and secondly, that we still don’t have any real idea of what’s causing it,” he said.
John and Trevor Fitzpatrick grew up at the Port in the 50’s/60s and have written a number of songs about their memories and experiences. John has given permission for a couple of their songs to be made available on the GSV website. Enjoy “Taperoo Beach” and “Port River Dolphins”!
ABC News 24 just broadcast an interview with Tony Abbott from Cairns in which he backs away from Marine Protected Areas because the science isn’t right! How predictable was that!? And how ironic when we think about the amount of dirty water that must be smothering the GBR right now.
The cow fish is a type of boxfish and are quite rigid. They are generally found on rocky reefs. We have about 20 species in Australia.