Thursday, 8 May 2014

There's a Mermaid hiding in our creek!

 Each successive modern generation is growing up in world that has less biodiversity and beauty than the one before. As a consequence the sense of loss at what is disappearing becomes diminished. Nowadays polluted creeks and lack of biodiversity have become the norm, a far cry from when the traditional Aboriginal owners were custodians of this land.

 It’s amazing to think that in suburban Sydney just a mere seventy years ago...platypus still occupied some of our creeks and streams. That was before most of the waterways were piped or sullied by storm-water drains and leaking sewage infrastructure. If we could suddenly turn back time to how the area used to be, then more people would realise the ugly truth of what our “civilisation” has done.

Just some of the junk removed from Manly Creek one Clean Up Australia Day
 Of course many of these creeks are now hidden away and choked by invasive weeds and discarded rubbish.  Incredibly though, some ancient denizens still cling to life in their murky waters, much like they have done for a large chunk of eternity.

 On Manly Creek, in the Northern part of Sydney, there is a place called Mermaid Pool (named after the young girls who used to bathe there in the Great Depression).  But a local native fish expert, Andrew Lo, insists that the real Mermaids are the fish themselves...and it’s hard to argue with his logic.

 Andrew was the guy who discovered that an amazing fish, which breathes through its skin and climbs up sheer rock faces, lives within the Manly Dam catchment area (in the upper sections of Manly creek-line).  This Climbing Galaxias population is the most northerly in Australia. It’s a living Gondwanan relic, but its clean-stream habitat is very vulnerable.   Members of the community once celebrated its birthday with a special 60 millionth birthday cake, a symbolic gesture during a protest blockade against development of its habitat. This area has since become a housing estate and one of the Galaxias’ creeks and bushland surrounds was ultimately bulldozed and concreted to make way for “progress”. Read  more about the Climbing Galaxias on the Australian Museum website.

 Back down the creek towards Manly’s surfing beaches you can still spot a number of other “Mermaids” which still migrate to spawn up this waterway just as they’ve always done...and they somehow still do it, despite the golf course dams, the pollution incidents, the choking exotic weeds, the irregular water flows, the algal blooms, the feral fish predators and the general lack of knowledge of their existence and consequently, any regard for their well-being..

 These are some of the native fish in question:-

 Jolly tail. The common galaxias spawns downstream in rivers and streams amongst vegetation on the banks of the estuary regions during a spring tide mainly in autumn. The eggs remain on the bank (out of the water) until the next spring tide when they hatch into larvae which are swept out to the ocean. For the next 5–6 months the larvae live in the sea and develop into juvenile fish, often referred to as whitebait.

The Striped Gudgeon is best recognised in the wild by the five to seven dark stripes on the sides of the body, and a dark stripe running posteriorly from the eye.
Andrew finds a tiny juvenile Striped Gudgeon during a survey

 Cox’s Gudgeon. Juveniles are able to climb waterfalls by rotating their pectoral fins so that the inside surfaces of the fins are pressed against the wall creating suction. 

Juvenile Cox's Gudgeon climbing a sheer rockface
Empire Gudgeon. Females are brown to golden and whitish below. In the breeding season males become bright orange-rea on the head and belly. The dorsal and anal fins become bright red-orange basally and with a dark sub-marginal stripe and lighter margins.

Australian Bass are an iconic, highly predatory native fish.Longevity is a survival strategy to ensure that most adults participate in at least one exceptional spawning and recruitment event, which are often linked to unusually wet 'La NiƱa' years and may only occur every one or two decades.

This Australian Bass was caught and released
The Bullrout should be handled with extreme care. The dorsal, anal and pelvic spines all have venom glands. A puncture wound from one of these spines can be excruciatingly painful.

The Flathead Gudgeon is primarily found on muddy bottoms, often amongst vegetation. The species occurs in freshwaters, but is also recorded from estuarine and protected areas in coastal bays. (There is also a Dwarf Flathead Gudgeon).

Firetail Gudgeon. This is a small native Australian fish that occurs in freshwater coastal streams. The body is generally grey to bronze with black scale margins. During the breeding season males can be almost black, with intense red-orange fins.

Firetail and Cox's Gudgeon

 Longfinned eel. Female eels can have millions of eggs in the ovaries. Developing leptocephali take about one year to return to the streams of eastern Australia. Glass eels arrive in New South Wales in early Summer. Those that make the additional journey south to Victoria arrive from January to late May. Young eels (called elvers) then swim upstream and spend a number of years maturing in freshwater.

Shortfinned eel. When they reach maturity, they stop feeding and migrate downstream to the sea, then anything up to three or four thousand kilometres to a spawning ground in deep water somewhere in the Coral Sea off New Caledonia.

Native fish migrate from the sea via Manly Lagoon up Manly Creek to breed.
In 2001 there was a herbicide spill near here from a local golf course which killed many thousands of fish. Manly Lagoon is rated as one of the most polluted waterways in Australia

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