Rockpooling Destination: Revisit to Lands End Peninsula Sept 2015

As seen in the previous post the bay has experienced some recent changes in deposition and erosion, resulting in the formation of a strandline and winnowing of finer material from the uppershore cobble beach. However, these are not the only changes to have occurred as this post will reveal...

As seen in the previous post a strandline has formed on the upper extent of the cobble beach. The newly formed strandline is important as it provide a resource for food and shelter, on an otherwise barren upper cobble and boulder beach.

This photograph taken in June, 2015 shows the absence of a strandline on this section of the shore. See post http://thesaltyscavenger.blogspot.co.uk/2015/08/rockpooling-destination-revisit.html 

This photograph taken in June, 2015 shows much of the upper shore bedrock and boulders covered by seaweed. See post http://thesaltyscavenger.blogspot.co.uk/2015/08/rockpooling-destination-revisit.html

However, by September, 2015 the percentage cover of seaweed on upper shore boulders and bedrock has reduced. 

Bedrock that was covered in ephemeral green seaweeds are now bare, whilst the Fucus sp is reduced to stumps.

There is a distinct lack of 'green' in this photograph compared to the photograph below that was taken in June, 2015.

Fucus sp cover the boulders, whist ephemeral green seaweed lace the diluted and sand scoured rockpools. June, 2015. See post http://thesaltyscavenger.blogspot.co.uk/2015/08/rockpooling-destination-revisit.html

What could have caused this change? Abrasion from the winnowed sediment? Seasonal die back or grazing? Since June there has been an increase in limpet abundance, c. Could their grazing be accountable?

Limpet density is higher than in June, could it be that individuals moved with the changing season. Seasonal migrations are noted in limpet species of British species (http://www.marlin.ac.uk/biotic/browse.php?sp=4220) or, were  the limpets swept in with  the fronds of the strandline , as noted for limpets in Advances in Marine Biology vol 16 or, maybe population abundance has peaked as a feature of the limpet life histories?

Topshell density had also increased behind the stack.

There were no signs of the tube dwelling amphipods among the seaweeds of the sediment filled pools, only the cases of thier tubes remained.

In June many amphipods were observed occupying tubes which were in  turn enveloped among the green seaweed. See post http://thesaltyscavenger.blogspot.co.uk/2015/08/rockpooling-destination-revisit.html

All other seaweeds except the fucoids exhibited no or little seasonal die back at this time and the remaining habitats remained largely unchanged since June, 2015.