Wednesday, 30 November 2016

Storms bring up peaty wood remains!!

Winter storms have brought up peat and semi- fossilised tree remains that aggregated among the strand line that otherwise comprised a variety of washed up bryozoan species. The peaty wood remains give an indication of the vast tracts of woodland and swamps that once stretched between East Anglia and continental Europe.

Wednesday, 9 November 2016

Rockpooling destination: Revisit West Penwith, June 2016

The rocky shore is comprised of boulders and bedrock with rockpools, crevices and gullies. Habitat classification: LR.HLR (High energy littoral rock) EUNIS: A1.1 , LR.FLR.Rkp (Rockpools) EUNIS:A1.41 and LR.FLR.Lic.(Lichens on supralittoral and littoral fringe rock) EUNIS: B3.11

The rocky shore is a high energy environment comprised of boulders and bedrock with rock pools, crevices and gullies.

The high energy environment of the shore leads to an extended lichen zone, that descends over much of the boulder field, which apart from Littorinids is relatively barren. Patches of lichens extend further down into the barnacle communities, which dominate from the upper to lower shore, inter-dispersed by shallow coralline rockpools in the mid shore, and deeper cobble filled rockpools on the lower shore. As the low tide mark is reached wave tolerant seaweeds lace the gullies.

Habitat classification:

LR (Littoral rock)
LR.HLR (High energy littoral rock)
LR.FLR (Features of littoral rock)
Biotope complex
LR.HLR. MusB (Mussel and/or barnacle communities)
LR.HLR.FR (Robust fucoid and/or red seaweed communities)
    LR.FLR.Lic.(Lichens on supralittoral and littoral fringe rock).
LR.FLR.Rkp (Rockpools)
LR.HLR.MusB.Cht (Chthamalus sp on exposed upper eulittoral rock)
LR.HLR.MusB.Sem (Semibalanus balanoides on exposed to moderately exposed or vertical sheltered eulittoral rock)

LR.FLR.Lic.Ver (Verrucaria Maura on  littoral fringe rock)
LR.FLR.Lic.YG (Yellow and grey lichens on supralittoral rock)
LR.FLR.Rkp.Cor (Coralline crust dominated shallow eulittoral rockpools)
Below are images of the organisms you may encounter in these habitats:

Among the mobile boulders and bedrock of the littoral fringe are populations of rough and small periwinkles with occasional limpets on the lower littoral. In this high energy environment organisms are confined to crevices and nooks, where they are buffeted from the full force of the waves and potential dislodgement. Habitat classification:  LR.FLR.Lic.(Lichens on supralittoral and littoral fringe rock) EUNIS: B3.11

During winter storms slabs of granite were broken away from the bedrock. Now in June this rock has not yet been colonised. 

The same area of bedrock in March 2016.

The exposed uppershore bedrock is covered in dense barnacles, with crevices jammed by mussels, anemones and coralline seaweeds. Small periwinkles occur among the barnacles, seeking shelter within the dead barnacle tests. The black lichen Lichina pygmaea forms tufts on the upper rock. All these organisms are characteristic of the biotope: LR.HLR.MUSb.CHT (Chthamalus sp on exposed upper eulittoral rock) EUNIS: A1.112. Darted among this habitat are small coralline rockpools. Habitat classification: LR.FLR.Rkp.Cor (Coralline crust dominated shallow eulittoral rockpools) EUNIS:A1.411.
Lichina pygmaea forms tufts of varying density

During the summer months rockpools experience prolific growth of ephemeral green seaweeds.
 The distribution of the ephemeral green seaweeds can be patchy.

In many cases the ephemeral green seaweeds dominate the coralline rockpools.

Ephemeral green seaweeds come to dominate many of the shallow rockpools during the summer months.

The coralline rockpools of the mid and lower eulittoral support a greater diversity of seaweeds than the upper, including Bifurcaria bifurcata, Corallina officinalis, coralinaceae crusts and ephemeral green seaweeds, along with beadlet anemones, china limpets, flat topshells and thick topshells. Habitat classification: LR.FLR.Rkp.Cor.Bif (Bifurcaria bifurcata in shallow eulittoral rockpools) Eunis A1.4113

Bifurcaria bifurcata in a shallow coralline eulittoral rockpool

Compared to March there are a greater diversity of  ephemeral and seasonal seaweeds, including Scytosiphon lomentaria.

On the sections of moderately exposed lower shore the diversity of seaweeds on the exposed bedrock also increases.
In these areas the abundance of barnacles is lower and the abundance of topshells, anemones, limpets, fucoids and red seaweeds increase. Habitat classification: LR.MUSb.Sem (Semibalanus balanoides on exposed to moderately exposed or vertical sheltered eulittoral rock) EUNIS: A1.113.

Red seaweed 'turfs' form between damp crevices and beneath overhangs.

The highest diversity of life is still found within the rockpools and on the lower shore were there is an explosion of seaweeds!

As the subtidal pools are reached the abundance of red seaweeds and kelp increase.

Monday, 26 September 2016

Common anemones of the shore

Anemones are some of the most colourful organism of the shore. Usually found within rockpools or crevices, anemones belong to the Anthozoa and posses stinging tentacles with which they trap and catch their prey. Out of water anemones look like bobs of jelly but when immersed their tentacles come out and they look quite different! Below is a guide to some of the common intertidal anemones of UK shores.

Beadlet anemone (Actina equina)
This is the most commonly encountered anemone on the shore and can be found on open rock, in crevices, beneath overhangs or in rockpools. It comes in a variety of colours and sizes.

Beadlet anemones on a harbour wall

Beadlet anemones look like blobs of jelly when out of water

They come in a variety of colours, including red, orange and green be carfeul as in some areas of the country green ones can represent a similar species!

When they are immersed in water, blue 'beads' can be seen encircling the column.

Strawberry anemone (Actinia fragacea)
The body of a strawberry anemone is spotty and looks a bit like a strawberry!

Snakelocks anemone (Anemonia viridis)
These anemones are usually encountered within rockpools and sometimes attached to seaweed. It can appear green or pinkish


Gem anemone (Aulactinia verrucosa)
This anemones is usually found in rockpools with sand and pebbles, which is occur amongst making it sometimes hard to spot!

The column has rows of white dots.

Dahlia Anemone (Urticina felina
The Dahlia anemone is the largest anemone encountered on the shore and often found in rockpools beneath boulder over hangs.

When the Dahlia anemones withdraws its tentacles its column that is covered in sand and shell can be seen. 

Anthopleura sp

Cereus pedunculatus


Wednesday, 20 July 2016

Rockpooling Destination: Revisit Lands End Peninsula, June 2016

Steep cliffs surround the bay, the lower craggy edges covered in lichens. The cliff bases and steeper bedrock transition between the lichen and barnacle communities with limpets, periwinkles and whelks. Boulders and bedrock on the shore host a similar barnacle community plus a variety of seaweeds, including where sand scour is event, ephemeral seaweeds. Rockpools occur sporadically throughout the shore, and a river flows downs from the cliffs.

The bay experiences a dynamic regime, alternating between periods of erosion (stony) and deposition (sandy).The underlying substrate is boulders and bedrock, however, variable amounts of sand may be deposited on top, sourced from the sand bar situated offshore. The communities encountered reflect the alternation between these regimes.

Please see previous blog posts:

For the past 21 months the shore has been stony and a series of rockpooling visits has documented the slow colonisation and succession of the sea shore communities of the newly available substrate. Now the shore is experiencing increased sand deposition which is influencing the communities previously documented. Notably, increased sand deposition and reduced seaweed cover and the infill of many of the sediment filled rockpools.

Below are images showing the change in sediments and habitats observed since April 2015/ March 2016.

 The shore in June 2016, shows an increased fucoid and ephemeral seaweed cover since March, 2015.

The rocky shore in March 2016 exhibits increased sand deposition, reduced seaweed cover and rockpool occurrence since June 2015.

The shore in June 2015 is predominantly comprised of bedrock and boulders and has an increased seaweed cover and rockpool occurrence. 

This photograph taken in September 2015 shows the typical Fucoid and ephemeral seaweed communities that covered the bedrock and boulders of the shore which has now  been mostly covered by sand.
Rather than fucoid seaweeds ephemeral seaweeds are now the dominant seaweed on this section of the shore.

This photograph taken in June, 2015 shows an area of the shore before the sand was deposited. 
Now sand has covered much of this habitat.

Sand continues to be deposited on the shore, covering the fucoid habitat.

Ephemeral seaweeds such as Porphyra sp cover rocks of the lower shore.