Monday 30 March 2015

Rockpooling Destination: Revisit South- West Penwith, October 2014 - Lichen Communities of the shore

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


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 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.


Winter waves had washed many 'by the wind sailors' (Velella velella) onto the shore. These extraordinary creatures are not one, but many organisms that form a colonial hydroid that floats on the oceans, driven by the wind against its sail. During winter storms hundreds can be washed up onto the shores of the Lands' End peninsular.  


'By the wind sailors' (Velella velella) are often washed up on the Cornish shores over Winter.
V. velella use their dorsal projections as a sail to sail across the oceans in search of small pelagic prey, which they catch with their stinging tentacles.

Habitat classification of the shore:



Substrate
LR (Littoral rock)
Habitat
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)
Biotope


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)
SubBiotope


LR.FLR.Liv.VerB (Verrucaria maura and sparse barnacles on exposed littoral fringe rock)

LR.FLR.Rkp.Cor.Bif (Bifurcaria bifurcata in shallow eulittoral rockpools)
Habitat classification of the shore anticlockwise from the top of the shore down:
 
LR.FLR.Lic.YG (Yellow and grey lichens on supralittoral rock)

 LR.FLR.Liv.VerB (Verrucaria maura and sparse barnacles on exposed littoral fringe rock)
LR.FLR.Lic.Ver (Verrucaria Maura on  littoral fringe rock)
  LR.HLR. MusB (Mussel and/or barnacle communities)
 LR.FLR.Rkp.Cor (Coralline crust dominated shallow eulittoral rockpools)
A crevice within the habitat LR.HLR. MusB (Mussel and/or barnacle communities)
 LR.FLR.Rkp.Cor.Bif (Bifurcaria bifurcata in shallow eulittoral rockpools)
and LR.HLR.FR (Robust fucoid and/or red seaweed communities).
Below are images of the organisms you may encounter in the lichen communities of the shore:


Lichens cover boulders of the supralittoral and littoral fringe. Yellow and grey lichens cover the boulders of the supralittoral  and below the black Tar lichen covers the boulders of the littoral fringe. LR.Flr.Lic.YG (Yellow and grey lichens on supralittoral rock) EUNIS: B3.111 and LR.FLR.Lic.Ver (Verrucaria Maura on  littoral fringe rock) EUNIS: B3.113.

 Yellow and grey lichens cover the boulders of the supralittoral. Habitat classification: LR.Flr.Lic.YG (Yellow and grey lichens on supralittoral rock) EUNIS: B3.111.

Tar lichen (Verrucaria Maura) covers the boulders of the littoral fringe. Habitat classification: LR.FLR.Lic.Ver (Verrucaria Maura on  littoral fringe rock) EUNIS: B3.113.


Periwinkles are the most prolific mobile fauna of the boulder field, where they seek refuge within crevices. Rough periwinkles (Littorina compressa nigrolineata) and occasional barnacles. Habitat classification: A variant of LR.FLR.Liv.VerB (Verrucaria maura and sparse barnacles on exposed littoral fringe rock) EUNIS: B3.1131.

Rough periwinkles (Littorina sp) and sparse barnacles.

Sparse barnacles, Small periwinkles (Melarhaphe neritoides) and Rough periwinkles (Littorina compressa nigrolineata) aggregate within pits and a depression of the boulder faces. 

Littorina compressa nigrolineata, sparse barnacles and limpet (Patella vulgata).

Littorina compressa nigrolineata

Littorina compressa nigrolineata

Wednesday 25 March 2015

Rockpooling Destination: Revisit of Land's End Peninsular, October 2014



The bay experiences a dynamic regime, alternating between periods of erosion and deposition. 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.


September, 2013
 The shore alternates between periods of deposition, sandy  and erosion, stony.
October, 2014

At the time of visitation the cove was comprised of boulders and bedrock with an occasional thin veneer of sand.


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 of the mid and lower shore host a similar barnacle community plus a variety of seaweeds, including where sand scour is event, ephemeral seaweeds. Rockpools occur throughout the shore, and a river flows downs from the cliffs.








Habitat classification:






Substrate
LR (Littoral rock)
Habitat


LR.HLR (High energy littoral rock)
LR.MLR (Moderate energy littoral rock)
LR.FLR (Features of ilttoral rock)
Biotope complex
LR. 


HLR.MusB (Mussels and/or barnacles on high energy littoral rock)
LR.MLR.BF (Barnacles and fucoids on moderately exposed shores)
LR.FLR.Lic.(Lichens on supralittoral and littoral fringe rock).
LR.FLR.Rkp (Rockpools)
LR.FLR.Eph (Ephemeral green or red seaweed communities
LR.FLR.CvoV (Littoral caves and overhangs).
Biotope



LR.MLR.BF.Fser (Fucus serratus on moderately exposed eulittoral rock)


LR.MLR.BF.Rho (Rhodothamniella floridula on sand scoured lower eulittoral rock)
LR.FLR.Lic.Ver (Verrucaria Maura on littoral fringe rock)
LR.FLR.Rkp.Cor (Coralline crust-dominated shallow eulittoral rockpools)
 LR.FLR.Rckp.SwSed (Seaweeds in sediment- floored eulittoral rockpools).
LR.FLR.Eph (Ephermeral green or red seaweeds (Fresh water or sand influenced)
LR.FLR.Eph.EntPor (Porphyra purpurea and Entomorpha spp. on sand scoured mid to  lower eulittoral rock)

Sub Biotope



LR.MLR.BF.Fser.R (Fucus serratus and red seaweeds on moderately exposed lower eulittoral rock)


LR.FLR.Rkp.Cor.Cor (Corallina officinalis and coralline crusts in shallow eulittoral rockpools)






Below are images of organisms you may encounter whilst rockpooling within these habitats:


Since April, 2014 the cove has comprised bedrock, boulders and cobbles. 


The littoral fringe bedrock supports a community of  tar lichen  (Verrucaria maura), periwinkles and occasional limpets and barnacles. Habitat classification: LR.FLR.Lic.Ver (Verrucaria maura on littoral fringe rock) EUNIS: B3.113.
Bedrock and boulders that a year ago were covered by sand are now slowly being colonized by fauna, many of whom appear to have moved down the rock from the Verrucaria maura and ephemeral green seaweed communities. Small periwinkles (Melarhaphe neritoides), Rough periwinkles (Littorina sp) and limpets occur on the gully sides, whilst rockpools and boulders are becoming colonised by ephemeral greens.
Periwinkles occur on the shore and are one of the most prominent mobile fauna of the littoral fringe and upper shore.
Small periwinkles (Melarhaphe neritoides).



Rough periwinkles (Littorina sp).
Rough periwinkle (Littorina compressa).
Rough periwinkle (Littorina sp).
Rough periwinkle (Littorina compressa nigrolineata).

Rough periwinkles (Littorina saxatilis agg and Littorina compressa nigrolineata).


Rough periwinkles (Littorina saxatilis agg and Littorina compressa nigrolineata).


Previously high levels of sand scour have limited species colonisation of the bedrock. Barnacles are scarce and organisms such as limpets (Patella valgata) and periwinkles are confined to crevices and leeward enclaves that offer protection from the waves and sand scour. Fucoids grow in occasional clumps, which are currently exhibiting seasonal die back. 


The cliff bases enable organisms to move up and down in response to the sediment regime and sand scour, as a result they support more stable barnacle communities with limpets, periwinkles, mussels and whelks. In the case of limpets the spray from the waves of this high energy shore, enable them to live far up the cliff base.Habitat classification: LR.HLR.MusB (Mussels and/or barnacles on high energy littoral rock) EUNIS: A1.11. 


Barnacles, Limpets (Patella Sp) and small periwinkles (Melarhaphe neritoides) cover the bases of the cliffs.


Small periwinkles (Melarhaphe neritoides) and barnacles.


Barnacles density is lower on the readily covered substrate of the lower cliff bases.

Common blue mussels (Mytilus edulis) cluster together in a leeward crevice of the cliff base.

M. edulis  and Limpets (Patella sp) aggregate in a leeward crevice of the cliff base.

M. edulis and a dog whelk (Nucella lapillus) within a crevice. 



Limpets (Patella sp), barnacles and N. lapillus.

N. lapillus
Beadlet anemones (Actina equina)  and Limpets (Patella sp) within a crevice.


The cliff bases hold a number of small coralline rockpools that support corallinaceae crusts, limpets and red seaweeds. Habitat classification: LR.FLR.Rkp.Cor (Coralline crust-dominated shallow eulittoral rockpools) EUNIS: A1.411
A coralline rockpool with limpets, corallinaceae crusts and ephemeral green seaweeds.
A deeper coralline rockpool further down the shore, with red seaweeds, including Corallinaceae crusts, Corallina officinalis and bootlace weed (Himanthalia elongata).


C. officinalis within a coralline rockpool.


A china limpet (Patella ulyssiponensis) which favours coralline rockpools.
Rhodophyta within a coralline rockpool.


Corallinaceae crusts are beginning to grow within the newly available rockpools.



A blenny  (Lipophrys pholiswithin a rockpool. Habitat classification: LR.FLR.Rkp (Rockpools) EUNIS: A1.41.




The distribution of fauna in the mid and lower shore is influenced by wave exposure, subtidal sand scour, fresh water runoff and desiccation. The result is a patchwork of biotopes that are not distributed evenly down the shore. Here the mid shore boulders are covered in ephemeral greens and the lower shore boulders are colonised by a patchwork of barnacles and fucoids. Habitat classification: LR.MLR. BF (Barnacles and fucoids on moderately exposed shores) and LR.FLR.Eph (Ephermeral green or red seaweeds (Fresh water or sand influenced).
This image of the shore taken in September, 2013 shows that there has since been extensive sand erosion, increasing the available hard substrate and abundance of ephemeral greens.  http://thesaltyscavenger.blogspot.co.uk/2014/02/rockpooling-destination-lands-end.html

By October, many of the perennial seaweeds are exhibiting seasonal dieback.


 The longer lived seaweeds of this shore have to endure periodic sand cover and scour.


The same general area in September, 2013 shows the seaweed covered by sand.
Blog post http://www.thesaltyscavenger.blogspot.co.uk/2014/02/rockpooling-destination-lands-end.html.
Thick topshell (Osilinus lineatus)


O. lineatus.



Ephemeral green algae (Entomorpha/Ulva sp) cover the relatively newly available boulders.Habitat classification: LR.FLR.Eph (Ephemeral green or red seaweed communities) EUNIS: A1.45.



The cliff bases  and boulders of the mid and lower shore that experience sand scour are also covered in Ephemeral green algae.  Habitat classification: LR.FLR.Eph.EntPor (Porphyra urpurea or Entomorpha spp. on sand scoured mid to  lower eulittoral rock). EUNIS A1.452


Ephemeral green algae and Porphyra sp cover mid and lower shore sand scoured boulders.

 In areas of the lower shore that experience sand scour the scour tolerant, sand binder (Rhodothamniella floridula) occurs. Habitat classification: LR.MLR.BF.Rho (Rhodothamniella floridula on sand scoured lower eulittoral rock)

The scour tolerant, R. floridula and ephemeral green algae (Entomorpha sp).


Mastocarpus stellatus, F. serratusR. floridula and the ephemeral green seaweed, Cladophora rupestris.


Where sand scour is reduced, barnacles, dog whelks (N. lapillus) and limpets cover the larger, more exposed boulders, whilst fucoid and red seaweeds colonise rock and boulders below. Habitat classification: LR.MLR.BF.Fser.R (Fucus serratus and red seaweeds on moderately exposed lower eulittoral rock).

M. stellatus forms a mosaic distribution with F. serratus. which is characteristic of the biotope LR.MLR.BF.Fser.R (Fucus serratus and red seaweeds on moderately exposed lower eulittoral rock).

F. serratusM. stellatus and C. rupestris with F. serratus showing seasonal die back.
The ephemeral green seaweed, Cladophora rupestris


Mastocarpus stellatus
M. stellatus


M. stellatus and the brown forking weed ( Bifurcaria bifurcata).

Blue raid limpet (Helcion pellucidum).

A polychaete on the lower shore.



Between the boulders of the lower shore are sediment filled rockpools which support a variety of seaweeds species including,  F. serratus and  red seaweeds including, C. officinalis, R. floridula and ephemeral greens.  LR.FLR.Rkp.SwSed (Seaweeds in sediment-floored eulittoral rockpools) EUNIS:A1.413.

Sand binder (Rhodothamniella floridula)
Rhodophtya
Possible black scour weed (Ahnfeltia plicata).
Rhodophyta

Coral weed (Corallina sp)


Combweed (Plocamium cartilagineum)


Lomentaria articulata


A hydrozoa

Gibbula umbilicus

A chiton
                                    A strawberry anemone (Actina fragacea).


 A. fragacea



Sea caves on the shore provide shade allowing species who are more sensitive to sunlight  to extend their occurrence beyond that of the rockpools. Habitat classification: LR.FLR.CvoV (Littoral caves and overhangs) EUNIS: A1.44.
M. stellatus, A.equina and coralinaceae crusts live in the shaded entrance of the sea cave.

Corallinaceae crusts occur within and extend beyond the rockpools of the cave entrance due to the shade provided by the overhanging cliff.



A raven looks among the shore......