Hill End to Spaniard Rocks & Back: Step-by-Step Part 6

As my walk continued from Hill End northwards on Rhossili beach, the dark drift patterns and fine strandline debris covering the sand eventually faded away to be replaced by dry sand ripple and swash/backwash patterns before arriving at the extreme north-east corner of Rhossili beach. This is the place where much of the flotsam ends up. It is not that Gower visitors are careless with their trash. Most of this stuff comes from far afield – sometimes as far away as South America. It does get periodically cleared away but is difficult to manage because the rubbish arrives and leaves with each tide, and can get buried or revealed from one high water to the next. Bicycle wheels, brightly coloured plastic pieces, fishing net and ropes, toothbrushes, balloon stoppers, and flip flops are common items along with the driftwood. The pile of organic and plastic rubbish lies adjacent to Spaniard Rocks which connect the tidal island of Burry Holms to Llangennith Burrows.

The geology here is interesting but on this occasion I focussed on the seaweeds which attach to the rocks along the water-filled channel between Burry Holm and Spaniard Rocks. There are many types intermingled. They include amongst others the brown Fucoid algae such as Toothed Wrack (Fucus serratus) , Spiral or Flat Wrack (Fucus spiralis), and Egg or Knotted Wrack (Ascophyllum nodosum). Bladder Wrack or Pop Weed (Fucus vesiculosus) was also present but not in its typical form. The numerous small, paired, almost spherical air bladders typical of the species were few and far between on specimens in the area where I was looking – so that there is confusion in my mind as to the identity of some of the weed I have named as Spiral Wrack.

There were also some red algae of the thin bladed type that dry out between tides into blackened streaks on the rocks (of the kind to which the lavabread seaweed belongs). Another red alga was the Sand Binder seaweed (Rhodothamniella floridula) which forms small humps of fine filaments trapping sand grains on rocks low on the shore; it is often found beneath the taller stalked fucoids. Finely branching red Polysiphonia lanosa was epiphytically attached to the Egg Wrack.

Of special interest this visit was the fact that the seaweeds were getting ready to reproduce. The Spiral Wrack had swollen receptacles on the forked frond tips that were not fully ripened yet. However, the Egg Wrack was ready to go. It has separate males and females. The male receptacles are bright golden green studded with orange pustules (conceptacles) that release a colourful fluid containing the sperms. I had seen these and reported on them before. This time I also saw the female receptacles which were dull green and covered with minute darker almost black blisters (conceptacles) containing the eggs. It almost seems as if you can see the eggs when you zoom in on the picture – actually just the light bouncing off the ripe eggs within the pustule.

Flat Wrack at Fermoyle

It was tranquil at Fermoyle on the Dingle Peninsula. Hardly a soul on the long sandy part of the beach, and only a solitary angler on the red rocky promontory at the western end. Vast swathes of short fruiting seaweeds clung to the rocks at the water’s edge, where the only sound breaking the stillness was the water gently lapping on the shore, while the seaweed danced slowly to the rhythm of the waves.

Three brown seaweeds: Furbelows, Sea Belt & Spiral Wrack from Studland Bay in spring

Common British seaweeds picture: Furbelows seaweed, Saccorhiza polyschides, washed ashore onto the sandy beach at Studland Bay, Dorset, UK, on the Jurassic Coast World Heritage Site (P1070086Blog1) 

Seaweeds usually start off life attached to rocks. Although Studland Bay is famous for its beautiful fine, clean sand, there are rocks to the west of the bay near Old Harry Rocks, and also the artificial substratum of what is locally termed the Training Bar. The Training Bar runs from the junction of Shell Bay and Knoll Beach (both are parts of Studland Beach) seawards in an approximately south-westerly direction. It is signposted with beacons on poles. Its purpose is to guide boats safely into the narrow entrance to Poole Harbour by the Sandbanks Ferry.

Seaweed becomes detached from the rocks for many reasons but most commonly due to strong wave action in stormy weather. The weed then floats around and often gets washed ashore. Because the weed may have been swilling around for a considerable time, the condition may be poor when it is found on the beach.

Most of the time the quantities of weed are moderate, scattered and impermanent  – it gets washed out to sea on the next tide. Occasionally vast banks of weed accumulate and do not disperse. If this happens, the National Trust (who own the beach) have hit on the novel idea of bagging it up and selling it as fertiliser for the garden. It makes excellent enrichment for the soil. For centuries, people have gathered seaweed for this purpose. In Alderney in the Channel Islands, for example, you can find evidence of the former wrack-gathering activities in the cobbled ramps that lead down to the beaches; these were constructed for the carts to get down to the shore. 

The top picture shows the commonly occurring kelp called Furbelows, Saccorhiza polyschides(Lightfoot) Batters, washed up at Studland Bay, Dorset. It is one of the largest brown seaweeds or Phaeophyceae. It has long strap-like leathery fronds. The stalk is short, flat and typically has a wavy ruff or frill either side of it as you can see in the picture below. Sometimes the stalk is twisted at the base. The holdfast at the base frequently has a warty and bulbous hemispherical appearance as well as rootlets. Lots of plants and animals prefer to settle here on both stalk and holdfast. The specimen below has red seaweeds attached to it. 

Common British seaweed photograph: Furbelows kelp, Saccorhiza polyschides (Lightfoot), showing wavy-edged lower stem and holdfast, washed up at Studland Bay, Dorset, UK - part of the Jurassic Coast World Heritage Site (P1070088Blog2)

Sea Belt or Poor Man’s Weather GlassLaminaria saccharina (Linnaeus) Lamouroux, is another large brown kelp but is easily distinguished from Furbelows. The frond is often a single blade and is has a crinkly surface that looks like that old-fashioned fabric known as seersucker.

Common British seaweeds photograph: Sea Belt or Poor Man's Weather Glass, Laminaria saccharina (Linnaeus) Lamouroux, washed up onto the sandy shore at Studland Bay, Dorset, UK - part of the Jurassic Coast (P1070094Blog3).

The stem of Sea Belt is short and slender as you can see in the photograph below. There are no lateral frilly edges. The holdfasts are a series of intertwined rootlets and there is no large bulbous structure.

Common British seaweeds photograph: Stems and holdfasts of Sea Belt, Laminaria saccharina (Linnaeus) Lamouroux, washed up on the sandy shore at Studland, Dorset, UK - part of the Jurassic Coast (P1070110Blog4)

You can find more pictures and information about these two kelps in a previous post – click here for Kelps at Kimmeridge Bay.

Studland Bay seaweed photograph: Flat or Spiral Wrack, Fucus spiralis Linnaeus, washed up on the sandy shore at Studland Bay, Dorset, UK - part of the Jurassic Coast World Heritage Site (P1070122Blog5)

One of the smaller brown seaweeds is Flat or Spiral Wrack, Fucus spiralis Linnaeus, pictured above and below. Like Bladder Wrack and Toothed Wrack it has a central midrib – but it doesn’t have any air bladders and the edges of the fronds are smooth. One of its supposed characteristics, and the one from which it gets the name Spiral Wrack, is the tendency of the fronds to twist -but you can’t rely on this feature alone for identification. When the forked tips of the fronds swell with reproductive products, they are lighter in colour and have a granular appearance. However, these swellings have a distinct longitudinal ridge or border around their edge which is a continuation of the blade or frond. This is one of the diagnostic features for the species.

There are more detailed pictures and explanations about Flat or Spiral Wrack click here for Flat or Spiral Wrack from Chapman’s Pool.

Common British seaweeds photograp: Flat or Spiral Wrack, Fucus spiralis Linnaeus, showing reproductive bodies at frond tips; Studland Bay, Dorset, UK - part of the Jurassic Coast (P1070123Blog6) 

Revision of a post first published 4 June 2009


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