| JNCCMNCR10221356 |
JNCCMNCR10000129 |
1982 Jones Menai Strait littoral rock survey |
JNCCMNCR10009618 |
1992-06-02 |
1992-08-02 |
DD |
Gorad-y-Gyt to Menai Suspension Bridge (Menai Strait) |
Point |
53.2265199873352 |
-4.1510788774388 |
WGS84 |
140167 |
Lacuna crassior |
FALSE |
|
|
FALSE |
Freshwater drains down the cliffs in places, resulting in luxuriant growths of Enteromorpha intestinalis which extend into the upper littoral. Lichens are poorly developed on these rocks, though the Verrucaria band can be detected where Enteromorpha does not blanket the shore. This shore is one which was visited annually from the 1930's by Prof. W.R. Brambell's easter marine zoology course, both for the general fauna of the limestone ridge and for the upshore shale fauna at Gorad y Gyt. Records resulting from this intensive collecting are numerous, often listed under the general locality name Cae Coch. Of particular interest were the boring mollusca of the lower shore; Hiatella was plentiful in the limestone and Zirphaea crispata in the soft basement shales. Collecting of the latter by student parties occasionally resulted in some damage since intact animals can be obtained only by attacking the rock with a crowbar. However, this kind of activity is much less common at the present time. The shore has always been subject to considerable deposition of fine sediment and it is probably this more than any other factor which limits the range of the species. There is evidence, so far inconclusive, that there is, in fact, more fine sediment in suspension and being deposited within the Menai Strait than was formerly the case. A complete fucoid zonation is present but Pelvetia and, to a lesser extent, Fucus spiralis, are limited by the prevalence of mobile substrata in the upper part of the shore. On the limestone shelves the factor limiting fucoid colonisation is generally the accumulation of fine sediment in depressions on the platform but where the rock is available for settlement well developed plants occur. At the lower edge of the shore, Laminaria saccharina and L. digitata become dominant, the latter large and with long stipes which, since they often bear Palmaria palmata as an epiphyte, are sometimes mistaken for L. hyperborea. This was the level of the shore which received the most attention from student courses; few new records have been added since the early 1970's and the main activity on the shore is now angling. Many anglers may be present on some days but they do not appear to cause significant disturbance since this shore is not suitable for bait digging. The shore retains this essential character to the Menai Suspension Bridge. All along, its sheltered nature is marked by the close approach of the land vegetation; the lower-hanging branches of the trees are trimmed off by the upper limit of salt water level presenting the appearance of having been neatly trimmed by a mechanical cutter. There are several seepages of fresh water and also untreated sewage (fortunately from small outfalls), which have a localised effect, increasing the quantity of green algae, in particular Enteromorpha intestinalis and Ulva lactuca. |
| JNCCMNCR10221270 |
JNCCMNCR10000129 |
1982 Jones Menai Strait littoral rock survey |
JNCCMNCR10009617 |
1992-06-02 |
1992-08-02 |
DD |
Penmon Priory to Black Rock (Menai Strait) |
Point |
53.2955578331601 |
-4.0600084379317 |
WGS84 |
145322 |
Dictyosiphon foeniculaceus |
FALSE |
|
|
FALSE |
Species lists compiled from records held at UCNW. At Trwyn y Penrhyn (630797) there begins an extensive shore of partially consolidated sediment. These reefs of shale, sandy mud and boulders have for many years been utilised for littoral ecology instruction and have been known to generations of marine biologists as Black Rock. It was one of the shores invariably visited by Professor W.R. Brambell's Easter Marine Zoology Course from 1931 onwards, and its rich fauna became well recorded. Black Rock rivalled Church Island on the richest locality in the Menai Strait. Taking three animal groups Porifera, Actinozoa and Decapoda, Black Rock proves richer in species in the two latter catagories, having 16 of the Straits' total of 55 Actinozon species and 23 of the 26 Decapoda to Church Island's counts of 14 of each. Only in Sponges is Church Island superior and even here Black Rock is the second richest site in the Strait. Black Rock is therefore a particularly important biological site; its value coming from its great variety of soft and hard substrata in a moderately sheltered situation and with strong tidal flows over the whole area. Sadly it must be added that the recorded richness depends on records which are mainly more than ten years old. Recent years have seen a decline in the shore's fauna. The habitats which were most rewarding were those in sand and under boulders, and both have deteriorated over much of the shore in recent years as a result of the activity of bait diggers. As an example, Dr C. Burdon Jones, who in the 1950's had worked on Saccoglossus ruber (one of the locality's interesting rarities) was unable to find specimens in the familiar localities when he re-visited Black Rock in 1982. The whole of the shore showed signs of massive disturbance when surveyed at about the same time. The larger boulders bear a well developed fucoid cover with plentiful Ascophyllum bearing Polysiphonia lanosa and Pylaiella littoralis. Barnacles colonise most stones, Balanus balanoides being dominant. Its major predator, Nucella lapillus is scarce on the small stones and appears in appreciable numbers only on isolated boulders on the lower shore where it occupies holes in the surface. Patella vulgata shells carry a well developed Barnacle cover. Southwards from Trwyn y Penrhyn, the lower shore consists of a dissected platform of consolidated mud and pebbles subject to limited wave action. Fucoid cover is well developed on the pebbles with F. spiralis extending far down shore on the very gentle slope and overlapping with F. serratus. At the lower levels are some particularly large limestone boulders, the most conspicuous of which was always visited by marine biology classes for its spectacular display of the anemone Edwardsiella ? cornea. This is the region of the shore richest in sponges. There are also numerous shallow sandy pools containing sand-tolerant algae on embedded pebbles. |
