Monday, 4 August 2014

Life in a Beach

Each area of coastline is different.  It is not a case of the same species be present is slightly different numbers, each place seems to be the product of different ecological rules.  Sandy beaches are normally somewhere where animals are very scarce, perhaps only a few ghost crabs are present.  However the beach at Archer Point, close to Cooktown, is literally crawling with life.

Amphipod burrows
Amphipod burrows near high tide line

Amphipod about 1 cm long.
An amphipod

I have never seen a beach covered with burrows all the way from the low tide mark to the high tide mark before.  I even had to dig up the ground to find out who was in the burrows.  Amphipods jumped out of the first handful of sand so must be just below the surface.

Amphipods are basically a small (1 cm long) prawn-like animal that walks on land.  They have very big eyes and are nocturnal.  When chased, they can jump like crazy to avoid being caught.

Since seeing the amphipods at Archer Point, I have kept my eyes open and have scanned several beaches which seem similar in terms of protection and sand properties.  Finding amphipods on these other beaches is a struggle.  Normally, there are a few amphipods under washed up leaf litter and seaweed.  It is unusual to find large numbers on a beach that is almost clear of plant debris.  I suspect that there is freshwater seepage concealed within the beach which some how helps the amphipods.

Recently 4WD vehicles were allowed back on many Queensland beaches.  Scientific research had shown that vehicles driving on the beach crush many of the animals that live in the sand and hurt the ecology of the beach. My position on this matter is that each place has to be assessed individually.  It is nice to be able to pull up right beside the sea and relax and I would not like to see every beach fenced off.  Many beaches are reworked so much by wind and waves that few living animals are present and driving on these beaches does little damage.  However it is repulsive to find tyre tracks all over remote beaches where people should be able to enjoy freedom from such things.  In this case, there is no reason to drive on the beach at Archer Point as the beach is only 300 m long and has an unusual ecology featuring vast number of amphipods which would suffer due to vehicles on the beach.

There is no point in driving onto this beach as it is so short, yet lots of people do it
Amphipod holes beside tyre tracks

No comments:

Post a Comment