Monthly update from Friends of the Bluff

     Calling your Bluff.. .

CALLING YOUR BLUFF - February 2007

Swans dabbling in the wake of yachts reflected in a wind-bristled sea; rippling vistas beyond lugubrious cormorants on bow rails wings spreadeagled and flat-footed pelicans sunbaking self-consciously on jetty bollards. Ah yes! The Barwon estuary really is just a postcard.
But the sun drenched postcard images belie the extraordinary contradictions that shape the estuary. And who would think from the photos that a regurgitating crab could have such an impact on the physical make-up of the estuary.
The Barwon estuary is a dynamic, shifting environment extending from the relative calm of the upper reaches, via the mud-soaked mangroves to the tempestuous lower reefs. The major influences of tide and weather dictate the accreting and conceding of sand, sucking, scouring, cutting and moulding the landscape on a daily basis. A built environment of breakwaters, retaining walls, boat ramps, drains and structures all impede the natural processes. Whatever happens upstream invariably impacts on all things downstream. The estuary fringe is sandy or muddy or occupied by reeds and grasses or salt and mangrove or moonah, sometimes all at the same time.
And at times the estuary is both wet and dry. Well, wet and not so wet
At low tide the expanse of sand and mudflats appear to be quite uniform in appearance but closer inspection shows it to be a mosaic of undulations, mounds, lumps, sandy ripples, moisten runnels and waterlogged depressions all sculpted by the activities of a host of birds, fish and invertebrates.. Breathing, burrowing, defecating, probing, scratching, nestling and expectorating all have a profound affect on the topography of the area.
A marauding horde of soldier crabs, for instance, has a radical influence on its environment. Emerging at low tide, thousands of these imperial blue storm troopers swarm across the sandflats in a dredging frenzy, processing huge quantities of sand through revolving mouth parts extracting organic detritus and tasty micro-algae tidbits. leaving the landscape littered with regurgitated sand pellets. When disturbed, soldier crabs, the only flavour of crab to walk forwards ironically turn sideways and corkscrews rapidly into the sand creating tiny dampened whelts and hollows. The distribution of these little globe shaped crabs is also dependent on the landscape. Preferring sodden depressions to the more drained mounds, their intense activities greatly disturb an otherwise smooth surface.

Far removed from poetic postcard gentility, the estuary is embroiled in a state of flux, constantly

by the influences of the really big and the really small. And don't get me started on the provocative sex and violent savagery of some its inhabitants.
As part of Festival of the Sea, the 2007 "Connection with the Sea" seminar will take an intimate look at our wonderful and fascinating estuary. With a panel of experts to guide us, five exciting field trips to choose from and our famous lunch this years seminar will be a must. Water, sand, mud, sex and violence-just another day in Barwon Heads. Sponsored by CoastAction and Friends of the Bluff, the seminar will take place on Wednesday March 14th from 9.15am at the Barwon Heads Hall. There is no cost but there is a need to book early to guarantee your place. Phone Dianne Moore on 52264669 for bookings and enquiries.
Now, swan poo is seagrass rich making it a great source of nourishment for bacteria and.......

 

Jon Duthie