Wildlife of the Menai Strait
The Menai Strait has a wide variety of habitat types and is home to over 1,400 recorded species of plants and animals. The area forms part of the Menai Strait and Conwy Special Area of Conservation (SAC). This is a designation which enables the protection of special habitat types and species (excluding birds) which are considered to be most in need of conservation at a European level.
The combination of strong currents in the Strait along with other environmental factors has led to the development of a number of rare features and unusual animal associations. For example, Halichondria panicea (a sponge) and Tubularia indivisa (a hydroid) live together, forming extensive mats over the sea bed in an area of tidal rapids. It is these very currents which both supply food and prevent the deposit of sediment, which allow these creatures to survive in huge numbers.
The variety of rock types and their complex formations present throughout the SAC provide many different types of subtrate for colonisation by different species of marine plants and animals.
This includes species which live on the surface of the rock such as seaweeds, barnacles, sponges and soft corals, and species that are able to bore into the surface of the rock, including piddocks, rock boring sponges and acorn worms.
Cobble and boulder areas provide under-cover shelter, as well as space between the rocks for more delicate species that are not able to survive on open rock surfaces. Areas of rock with fissures, cracks and crevices provide habitat for shade-tolerant species.
The waters of the whole SAC are relatively turbid which limits the water depth to which seaweeds within the SAC can survive. Sediment type has a strong influence over the types of marine species which are associated with intertidal and subtidal sediment areas within the SAC. The surface of the sediment is often apparently devoid of vegetation, although mats and films of micro-algae are common.
Muddy areas are highly productive, containing high levels of organic material and are very important to the marine ecosystem, playing an important role in marine food chains. They generally support very large numbers of an individual few species. Diversity of various species, including marine worms tends to increase with increasing levels of sand and gravels, particularly where conditions result in sediments being muddier. In areas of coarse sand, where the sediment is of similar grain size, the sediment is easily moved by waves and tides and only a few specialist species are able to exist in these areas.
Strong tidal streams result in characteristic communities, dominated by filter feeding animals fixed onto or into the seabed, typically including soft corals, hydroids (sea firs), bryozoans (sea mats), large sponges, sea anemones and mussels. The fast-flowing water brings a good supply of food and nutrients, supporting the growth of these animals and, in many areas of the strait, sponges are able to grow to unusually large sizes.
In areas of extremely strong tidal currents, species are restricted to those that grow as thin encrusting layers across the seabed, anything larger would get swept away. The lack of strong wave-action within much of the SAC results in the rocky shores being dominated by seaweeds like the serrated wrack Fucus serratus and kelps such as oarweed Laminaria digitata. Areas within the SAC which are exposed to moderate wave-action, such as the north Penmon coast are dominated by a mixture of seaweed, mussels and barnacles, which are resistant to dislodgement by waves.
Waves can also influence the size and shape of animals and plants. For example, mussels found on rock habitats in sheltered areas within the strait are much larger than those on the north Penmon coast because they are able to open their shells and feed more frequently in the more sheltered conditions.
The nationally scarce dwarf eelgrass Zostera noltii is found in the area between Beaumaris and Lleiniog.
Birds Of The Menai Strait
The Straits are home to a wide variety of shore and wading birds, such as little egret, oystercatcher, curlew and redshank. The famous Puffin Island stands at one end of the Strait. During some winters, internationally important flocks of common scoter have been observed, gathering to feed upon the plentiful populations of bivalve molluscs.
Magical Bioluminescense
At the North West end of the Menai Strait you will find Penmon point. A great place to look out for a magical light show made by plankton. The best time to see the plankton is when it is dark. The plankton is usually spotted during astronomical twilight, which is between 11pm and 3:30am in the UK in June and July.
Video courtesy of You Tube- Ray Leigh