December – what’s out and about
The Menai Straits (Afon Menai in Wlesh – meaning the river Menai) separates the Isle of Anglesey from mainland Wales. It is a narrow stretch of shallow tidal water and is home to a diverse range of marine wildlife. It is designated as an Area of Outstanding Natural Beauty and an Special Area of Conservation forming part of a network of protected sites (Natura 2000) across Europe.
One of the best and most enjoyable ways of accessing the Menai Straits is by water. From here the inter-tidal shore line can be reached as part of a fun and adventurous journey.
Orange lichen Caloplaca marin encrust exposed rocks at the top of the shore above the high water line forming a colourful band of painted rocks.
Channel wrack Pelvetia canaliculata can be found in a band below the lichens as you walk down the shore. They live in an area which only gets covered by the largest – spring – tides which are caused by the new and full moon events. Channel wrack spends most of its time out of the water presenting huge challenges for a marine algae.
In the middle shore Egg wrack Ascophyllum nodosum forms a dense band of seaweed. It contains a large air filled bladder which helps it float in the water aiding it to reach the light to photosynthesise. It is rich in minerals so is used in human foods and also for fertilising crops.
The Flat periwinkle Littorina littoralis is a common shellfish on sheltered shores where they feed on brown seaweeds especially egg wrack. The large shell acts a a lung to keep oxygenThe shell colour varies widely with the commonest being yellow. When seen underwater from below on seaweed the shell is camouflaged as it has a similar colour to the bladders on the seaweed. This way it gets protection from its fish predators.
The olive green form of the Flat periwinkle is the same colour as the brown seaweed when viewed from above water. In these situations they are more likely predated by gulls and other shore birds. This adaptation in shell colour provide an advantage for camouflage from a variety of different predators.
Lugworms Arenicola marina are easily recognised by their coiled casts which are commonly seen on inter-tidal sand and mud flats. The animal is not often seen unless your curiosity gets you digging! The lugworm lives in a U-shaped burrow and has adapted to its low oxygen environment by a well developed system of blood vessels to help carry oxygen.
