Washed Up This Week

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.

Image from Fishes of Australia website (SA Museum specimen)

Image from Fishes of Australia website (SA Museum specimen)

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.

 

 

Magpie ray story on ABC 891

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.

Young leatherjacket at Henley Beach, March 2013

Young leatherjacket at Henley Beach, March 2013

 

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.

 Scott Ashby,

Chief Executive, Primary Industries and Regions SA

 

MODIS satellite image of the gulfs in early March

MODIS satellite image

This image taken on March 6th shows much higher chlorophyll levels on the western sides of both Gulfs – indicated by the red colour. Deeper waters, with 10x less chlorophyll are blue or green coloured.

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.

 

 

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.

Cow fish

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.

Fish are sometimes stranded alive in pools on outgoing tides, but usually they are dead, and a rare feast for seabirds. You might occasionally also find freshwater species on metropolitan beaches following rains that have washed fish, such as European carp, out of the Torrens.

Porcupine fish

Porcupine fish (a.k.a. balloon fish, puffer fish) Diodon sp

Best not to step on a dead, dried porcupine fish! It has nasty, long sharp spines. In a live fish the spines provide defence against predators, as does its ability to inflate its body, making the spines stick out – like an echidna in defensive mode. These fish are not built for speed.

 

 

 

Toad Fish Tetractenos

Toadfish – don’t eat!

These fish grow to about 15 cm (this one was about full size) and are common in shallow water in southern Australia. Like other members of this family, toadies are poisonous.

 

 

 

 

 

Short-headed Lamprey (a.k.a. Australian Lamprey) Mordacia mordax

Lamprey

Looking like an eel, these fish grow to about 50cm in length and move from marine to fresh water to breed. In the sea they parasitise other fish. Most fish have jaws, but Lampreys are blood sucking and have a round funnel-like mouth with many small sharp teeth.

All crabs belong to the group called the Decapoda – Latin for ‘ten legs’.

There are lots of crab species in the Gulf, and they range in size from tiny to quite large. Most have hard shell (carapace) unless they are moulting. This happens as the crab is growing. Calcium is reabsorbed from the old shell, which gradually becomes softer, and is used to grow its next shell. When the new shell is ready the old shell is cast off, and the new shell hardens quickly. Sometimes the soft, old shell is washed up. Hermit crabs don’t have a hard carapace, and they use empty marine snail shells to protect their soft bodies. As they grow they need to find larger snail shells. If you are collecting shells on the beach, be sure to check that there is not a hermit crab in residence!

The Blue Swimmer is probably the best known crab, and is sought after because it is abundant and tasty! If you see one in the water while you are swimming, or in a tidal pool, don’t get too close – a nip from their claws is painful.

Sand crab carapace – note the two dark red sots

Sand crabs are pale reddish with two darker spots on the carapace.

 

 

 

 

 

 

 

 

 

Spider crabs range greatly in size, but characteristically have really long legs.

Spider crab near Henley Jetty – approx 20 cm across the carapace

 

 

 

 

 

 

 

 

 

 

Tiny spider crab – approx 1 cm across the carapace

 

 

 

 

 

 

 

 

 

 

 

Rock crabs are smaller and chunkier than the swimmers and spider crabs, but are really good at wedging themselves under rocks and in cracks.

There are a few types of eggs or egg masses that are easy to recognize on the beach. Considering how many marine animals actually lay eggs, it is a bit surprising how few we see regularly!

 

The egg mass produced by a couple of species of the moon snail (Polinices conicus and P sordidus) is often mistaken for a jellyfish. That’s because you can barely see the miniscule eggs, but they are held in a transparent, firm, sausage-shaped jelly matrix. They start to appear on the beach in spring.

The moon snail (Polinices sp) lays eggs in a jelly-like matrix.

 

Eggs mass of the moon snail – not a jellyfish

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Squid eggs are also easy to recognize because they are soft, whitish and clumped together in a bunch.

A clump of squid eggs. There can be four or five eggs in each of the ‘fingers’.

 

 

 

 

 

 

 

 

 

 

 

 

 

A slightly mangled Port Jackson Shark egg.

The most common shark egg cases we find locally are those of either the Port Jackson sharks or skates. They are dark brown, rubbery and shiny when fresh, but when hatched or dry become hard brittle. The Port Jackson shark egg case is spiral shaped, tapering from the base to the tip. Skate egg cases are shaped like small pillows, with tendrils on each corner.

Hot water at Henley!

During the winter storms this year a couple of unusual objects washed up on the beach at Henley. This is the downside of making your own artificial reef – apart from the fact that it is dumping rubbish at sea. A big enough storm can dislodge very heavy objects, let alone hot water heaters and mattress bases.

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