Beachcombing discoveries on Bailiwick of Guernsey sea shores

March 4th, 2013 by Melanie Broadhurst

The Alderney sea shore showing the strand-line (click image to expand - ©Melanie Broadhurst)

The Alderney sea shore showing the strand-line (click image to expand – ©Melanie Broadhurst)

Exploring the strand-lines of the intertidal shore provides an excellent insight into the rich marine life of the islands of the Bailiwick of Guernsey.

Strand-lines occur at the upper-most part of the sea shore, which marks the very edge of the sea.

A variety of marine life debris is left behind from each incoming tide, which can give beachcombers (a person who searches/ combs strand-lines) a different, yet exciting find, on a daily basis.

Beachcombing hunts are particularly interesting during spring tides, and during winter periods, when storms are more frequent and intense, leaving behind a wide range of marine debris.

Marine algae (seaweed) debris is one of the most common sights along the strand-line, ranging from large kelp stands (brown algae) to small delicate red algae species (known as Rhodophyta), such as Corallina officinalis.

Seaweed debris provides valuable organic material for the marine environment, refuge for marine invertebrates, and food for important seabird species.

A closer investigation of the washed-up seaweed debris can reveal fascinating marine life.

Dried sponges, starfish, sea mats, including hornwrack (Flustra foliacea) and even live insects can be found hidden amongst the seaweed fronds.

Mollusc shells such as scallops, limpets and periwinkles are also a frequent find, including strange looking loofah balls, which are actually whelk egg sacks.

A ball of empty whelk egg cases on the strand-line of an Alderney beach (click image to expand - ©Melanie Broadhurst)

A ball of empty whelk egg cases on the strand-line of an Alderney beach (click image to expand – ©Melanie Broadhurst)

Another common sight along the strand-line is cuttlefish bones, traditionally associated with budgerigars and pet shops.

A cuttlefish bone in the strand-line on an Alderney beach (click image to expand - ©Melanie Broadhurst)

A cuttlefish bone in the strand-line on an Alderney beach (click image to expand – ©Melanie Broadhurst)

Rarer finds include ray and shark egg cases, which are also known as mermaid’s purses.

Each egg case contains one shark or ray embryo which develops over several months. The egg cases found along the strand-line are predominately empty, which the juvenile shark or ray has left behind.

A number of different ray and shark egg cases are found throughout the Channel Islands, including the blonde ray (Raja brachyura), smalleyed ray (Raja microocellata) and the small-spotted catshark (Scyliorhinus canicula).

Excitingly, ray egg cases have been recorded this year across Guernsey’s strand-lines by La Société Guernesiaise.

Mermaid's purses. Three individual egg cases of a ray washed up on the sea shore at Champ Rouget, Chouet and discovered on 17 February 2013 (click image to expand - ©RLLord)

Mermaid’s purses. Three individual egg cases of a ray washed up on the sea shore at Champ Rouget, Chouet and discovered on 17 February 2013 (click image to expand – ©RLLord)

This on-going recording of egg cases and other marine life across the strand-line is particularly important, to understand Guernsey’s diverse marine life, over time.

Please visit the Shark Trust website for further information on shark egg cases and recording them along your nearest strand-line.

If you are also interested in recording marine life across Guernsey’s diverse marine environments, please contact La Société Guernesiaise, through Jessica Jennings by emailing [email protected]

While beachcombing please be aware of the rising tide, collect litter, wear suitable gloves and clothing, and avoid disturbing seabirds that use the sea shore for feeding and nesting.

 

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