Tuesday, February 22, 2011

Taking on the winter shape…already

vb beach pano big-1

The beach is loosing the distinct flatter area of dry sand from the upper beach zone and a continuous sloping curve, typical of the winter shape (or winter berm) has quickly developed for the beach profile. The reason is clearly the strong onshore winds, strong swells and powerful waves crashing onshore. The highest tides are however not reaching the scarps from previous erosion.

In previous years these changes have more typically occur in April/May.

Monday, February 14, 2011

Tumbling Tumble Weed

spinifex seedAustralia doesn’t really have the true (by which I mean the American Western Movie Style) tumble weed but the seed of the humble Spinifex, Spinifex sericeus comes very close. This grass also known as the beach spinifex is crucial for dune stability. It usually forms tussocks and has long rhizomes that spread out through the sand and hold the dunes in place. It can easily be propogated from rhizome cuttings planted in damp sand. Interestingly this spinifex has separate male and female plants. The above photo shows the dried flower, from a female plant, now holding the fertile seed. It blows along the beach following the shifting sand and thus populating newly formed dunes. A very clever design!

spinfexmarram grass

The introduced marram grass, is now competing with native spinifex all along the Venus Bay beach and may eventually replace all the native spinifex. The marram grass also helps stabilize the dunes, that is why it was originally introduced, but its dense growth may contribute to steeper dunes by entrapping more sand, at the expense of the upper beach zone (ie summer berm) This may be one factor in an increased susceptibility to direct wave erosion.  The dense grass mat also inhibits other dune pioneer plants and may reduce the traditional nesting and foraging habitat available for some small animals and birds. For example at Summerland Beach on Phillip Island the change in dune shape bought about by marram grass replacing spinifex has meant special temporary penguin tracks have had to be constructed up the dunes to give access to the little penguins breeding areas.

Friday, February 11, 2011

Mess Up Days

You may have noticed some of the Pacific Gulls (Larus pacificus) looking a bit messy, this is just the juvenile birds moulting into their distinct black & white adult plumage. It is not due to oil or other pollutants clogging their feathers, just typical adolescent attire.

Tuesday, February 1, 2011

The Hooded Plovers Web of Life

I found this wonderful illustration on the Culture Victoria website under stories/ Land & Ecology.
The first ring has all sorts of tiny crabs and critters that Hoodies like to eat. The second ring shows some of the birds that share the beaches with Hoodies - some that stay there all year round and others that fly long distances to spend summer on the beach in Australia. Most birds share the crabs and critters with the Hoodies, but others like to eat the Hoodies, and other birds!
These creatures are linked together because they need each other to survive. Of course, humans are part of this web of life, and we have an affect on how it works.
More details on the CV website