COUNTRYSIDE COUNCIL FOR WALES
SITE OF SPECIAL SCIENTIFIC INTEREST: CITATION
ANGLESEY RHOSNEIGR REEFS
National Grid Reference: SH313727
Site Area: 27 ha
Rhosneigr Reefs consist of a group of rocks and flanking reefs situated just to the south west of Rhosneigr on the west coast of Ynys Môn. Extensive areas of intertidal bedrock and sandy sediments are included within the site.
The site is a classic area for the research and educational study of marine algae. It is of particular importance for the abundance and variety of rock pools present, formed by the combination of extensive bedrock outcrops with the shallow-sloping sandy beach. Rock pools are present on the shore at a range of tidal heights. The size of many of the pools permits a considerable upwards extension of many species and is particularly well represented here. The extensive lagoon formed at low water contains a rich marine flora and fauna. Shelter provided by outlying rocks minimises sand scouring and enhances development of these communities.
In addition to a high diversity of littoral and shallow sublittoral algae present in these pools several less common or rare species such as the red algae Laurencia obtusa occur. Faunal communities are similarly well developed and include the spider crab Pisa tetraodon near its northern limit in the British Isles.