Habitat point records from 1986 Hiscock mid-Wales' sarns sublittoral survey
This survey was carried out to describe the sublittoral fringe communities on and around the Mid-Wales Sarns (Sarn Badrig, Sarn-y-Bwch and Cynfelin Patches), and to assess their scientific interest and nature conservation importance. The Sarns (reefs) are interesting geological features, being shallow sublittoral glacial moraines. The survey was conducted from the hard boat `St Margaret', and based at Abersoch on the Lleyn Peninsula in North Wales. Daily trips were made out to the reefs, and diving operations were based on the hard boat with inflatable tender for divers. At each site surveyed, records were made of abundance of plants and animals, and habitats were described. Suction samples were taken of sediment infauna at several sites. Photographs were taken to illustrate habitats, communities and species. The Sarns were remarkable for the extensive areas of distinctive communities on `unstable' substrata. A wide variety of algae, particularly Phaeophyta (brown algae), was recorded. At most survey sites, algae were dense and animal species were fewer and less varied. Twenty sites were surveyed, and descriptions of the different habitats and communities found on the reefs are given. The reefs were composed entirely of `unstable' substrata, of a wide range of sizes from large boulders down to fine sand. Distinctive communities dominated by ephemeral algae, were present in the sublittoral fringe on the reef crests, where there were mixed substrata exposed to fast tidal currents and strong wave action. In slightly deeper water, dense foliose algae dominated all hard substrata, with few animals present. Between 4 m and 9 m, Halidrys siliquosa forests covered extensive areas on boulders and cobbles in sediment. Pebbles were patchy but with a characteristic flora. In deeper water off the ends of the reefs, animal communities with a wide variety of species were present on tideswept boulders. Areas between the reefs were mainly covered with sand, and not investigated thoroughly. The conservation importance of the reefs as a whole is assessed, and of the 10 community types described. 11 algal and 4 animal species are identified as being of particular scientific interest. Many of the communities described are considered of regional or local importance; however the current-swept reef crests and the extensive Halidrys forests are considered to be of higher importance. The reefs as a whole are probably unique sublittoral features in the British Isles. Further work is recommended on Sarn-y-Bwch and Cynfelin Patches, both inadequately surveyed. The large boulder habitat, and areas at both the seaward and landward ends of the Sarns deserve further study.
dataset
name: 1986-Hiscock-mid-Wales-sarns-sublittoral-survey.csv
bd62e146-ff92-41b7-aca8-4b0e8b4dacbf
eng
Hiscock (1986) Sublittoral survey of the mid-Wales sarns (reefs): Sarn Badrig, Sarn-y-bwch and Cynfelin patches. July 2nd-9th 1986.
oceans
Marine
Marine Recorder
JNCCMNCR10000125
Habitat
MNCR
-4.419117302
-4.120066556
52.7978522
52.44396472
1986-07-02
1986-07-09
publication
2007-05-22
This survey was extracted from a Marine Recorder snapshot.
Comma Separated Values
Unknown
Open Government Licence v3.0
no limitations
Digital and Data Solutions, JNCC
custodian
Digital and Data Solutions, JNCC
pointOfContact
2018-05-17