Bay artificial reefs and their side affects

[liltuffy]

Well fellas after venturing offshore on Thusday and calling past Wello to check a few crab pots on the way home I've noticed of late a "brown silt" covering the pots and rope.

This stuff is not the horrible weed or slime that sometimes appears there rather a medium brown dirt. If you vigorously wash the pots off in the water it comes off.

This stuff seems to be putting the crabs off and not only that I can only surmise what a large amount of sediment would be doing to the reefs there.

All this green zone stuff and additional EPA measures (like expanding Harry Atkinson arti) to supposedly placate the locals to protect our bay seems to be damaging or perhaps killing off large sections of inshore reefs.

I don't really fish there but I know a heap of other Ausfishers do, has anyone noticed an unusually poor fishing result from the area for this time of year??

Craig

[Kleyny]

I highly doubt the silt would be coming from the arti reefs. More like it would be coming from all the earthmoving a developement up in the riverand surounds. their silt catching is very poor to say the least.

neil

[honda900]

Its a good point you make tho,

if you put down artificial reefs the currents and water movement have to move around the obstructions changing the landscape around the structure.

Regards
Honda

[oldboot]

The silt may be a result of some dredging...... or if they are dumping the " new material" out at harrie's it may be disturbing the bottom or may have fine material in the load.

I doubt very much that an established arti is going to be outputting silt.

If you check out a chart of that part of the bay....it is not hard to see what sort of effect the port construction has and will have on current flows arround wello and nearby areas.

from what I understand the tidal flow on the rise comes arround the west of Green and King..... it loops arround into the swimming bay..... as the spit submerges ( about 1 to 2 hours off high depending on tide flow) the current comming arround the east of green meets it and the flow reverses across the spit.......so the predominating rising tidal flow comes from the northern bay where it is deep......and past the port and major channels.
I have no scientific confirmation.... just my own observation and testimony of others.

remember tidal flow generaly comes from deep to shallow....... so unless there is a river or stream dumping material ( I don't think there is) it will be comming from deeper part of the bay.....or the bris river.

so I recon the silt willbe comming from arround the port or the channels.

cheers

[straddie]

They are still dredging Manly Harbour for the expansion so it could well be some runoff from there. There are a variety of sludges that form after winter as weed grows then dies, rots and turns into bubbly stinking messes in places. Hopefully it is the latter as anything originating from the bottom of Manly Harbour can't be good for you in my opinion.

[CreelReaper]

Straddie, the fish caught from Manly harbour still taste all right though!!

From memory, I think this sludge/mud whatever it is happens roughly at this time of the year and has done for the last 20 odd years. I think it might be as suggested, the dying off of some of the seaweeds/algae and is stirred up by the windy conditions that frequent this time of the year.

It has probably been more prevelant since the canals went in though.

Shane

[choppa]

a couple of websites that may help with arti's,,,,

http://www.environment.gov.au/coasts...ing/reefs.html

http://www.pir.sa.gov.au/fisheries/r...tificial_reefs

http://www.dpi.nsw.gov.au/fisheries/...tificial-reefs

the first site gives a laymen term on what conditions etc are expected to be fulfilled prior to a permit being granted

the second i included purely due to the fact that south australia has the most numbers of arti's (i believe) in australian waters,,,, this site shows locations,,, but interestingly what the reef is made up off

the third is what is (again i believe) the preffered method of arti make up,,,,, once more ""interestingly""" click on the photogallery prompt,,, good to see that something constructive is being done

choppa

[Lucky_Phill]

Thanks Chop....... I hope the " Tyre Modules " that have been used ( in SA ) were done many years ago, as this type of arti is NOT GOOD.

Even concrete is not ideal. But :-

The Reef Ball modules are a patented mold supplied by the Reef Ball Development Group and are made from a special mix of concrete that enhances marine growth while withstanding saltwater corrosion.

That photogallery is good. The arti's sure seem to be working well.


Natural rock and steel ' fish balls / pyramids are deemed the best. It is also amazing how quick a whole " habitat " can emerge from a sunken ship. HMAS Brisbane is an ideal example. Within months, it had attracted many forms of fish and plant life.

Phill
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[JRBK]

There is a silt trail on the redcliffe side of the hornibrook bridge where they're doing the bridge extension. Heads from the new revetment wall towards the brisbane river.
Has anyone ever noticed that the Pine River side of the old Hornibrook Bridge has silted up? I'm sure at low tide, the mud flats weren't exposed as much as they are nowadays.
Craig, i think the main problem is the dredging of the manly harbour, the shipping terminal extension, plus all the other development along the foreshores, which state government would allow before work commences.
And they want to have a go at the rec fisho? Think they should be looking in their own backyard prior to stopping others.
Mark

[oldboot]

There are lots of places that have silted up.

you just have to look arround wello point, thompsons beach and a heap of other similar places and the water depth is very much lower than it was 20 years ago.

What are the causes... good question...... many of these effects are very long term...... But I am sure some of the are short tern caused by development.

I am sure there are boffins that think the have a computer model they will show it all................ but who are they kidding........very few of these software models can be proven accurate or otherwise.

Shifting sand..... thats how it works.. it comes it goes.

cheers

[harry_h01]

Part of the cause to the silting of the Pine has been the extension of the Brisbane River Loading docks.

The original plans called for pipeing under the wharves to allow for the natural flow of water. This didn't happen and now there is a restricted flow of water in and out of the upper bay area. This has lead to the increase of silt being deposited in the Pine River and other reaches.

Harry

[Horse]

One of the excuses the EPA used for their poor report card score on Moreton Bay was the flooding of the Logan River.
If they would start to manage land use and runoff along with habitat destruction we would have a much healthier Bay.
It must be easier to attack fishos

[CreelReaper]

Absolutely right there Horse...... it is politically incorrect to target the real problems i.e. farming, land clearing, habitat loss and so on and so on. It is also an added bonus for them because they get to stop us neanderthal rec anglers from killing fish......