Habitat point records from 1989 UMBSM northern Firth of Clyde sealochs survey

The Cowal peninsula and mainland around the northern Firth of Clyde are deeply indented by six sealochs: Lochs Riddon, Striven, Goil, Long, the Holyloch and the Gareloch. The first two are connected by the East Kyle of Bute, a shallow channel running between Bute and the mainland. Loch Long is the largest fjordic loch in the group; Loch Striven has some similarities to Loch Long and is the second largest. Loch Goil forms a north-west trending branch of Loch Long, separated from the main body of the loch by a shallow sill. The latter three lochs all have a small percentage of intertidal to total area. The Gareloch is relatively shallow without subtidal rocky features, but does have a sill towards the mouth. The main feature of Loch Riddon is the Ruel Estuary, which has been designated a Site of Special Scientific Interest. The entrance into the East Kyle from Loch Riddon is via the shallower tide-swept narrows around the Burnt Islands; the area experiences the strongest current surveyed in the north Clyde sealochs. The Holyloch has no sill/basin features, the seabed sloping gradually out to deeper water in the Firth of Clyde. Like the Gareloch, it has a paucity of sublittoral bedrock. The whole area has been affected by sewage pollution with some improvement over the last 25 years, but the effects are still noticeable in the Gareloch and Holyloch. There is a strong Naval presence throughout the lochs with large submarine bases in the Holyloch and Gareloch. Twenty-one littoral and 82 sublittoral sites were surveyed, from which 27 habitat or community types were described. A list of the taxa recorded is also given. All the lochs in this system were characterized by sheltered communities. Only a few shores had communities typical of moderately exposed conditions, dominated by barnacles, the majority being fucoid-dominated and giving way to Laminaria saccharina forests in the infralittoral. Algal diversity in the infralittoral was low throughout the lochs, grazing echinoderms and chitons leaving large areas of denuded rock with abundant encrusting coralline algae. Steeply sloping bedrock in the circalittoral supporting a Protanthea simplex/Neocrania anomala community with Sabella pavonina and Ciona intestinalis. On most sites, however, bedrock and boulder slopes finished around the limit of the lower infralittoral/upper circalittoral and were replaced by shelly and sandy mixed sediment slopes with mud, finally leading onto mud plains in the deeper areas of the lochs. Scavenging mobile species, including hermit crabs, gobies and dragonets plus sediment-burrowing anemones Cerianthus lloydii, slender seapens Virgularia mirabilis, burrowing and tube-forming polychaetes and burrowing bivalve molluscs were found on these mixed sediments. Deeper mud, well worked by crustaceans including the Norway lobster, Nephrops norvegicus and the echiuran Maxmuelleria lankesteri was found in most of the lochs, other areas having beds of burrowing brittlestars, Amphiura spp. The large cerianthid anemone Pachycerianthus multiplicatus was also found in muddy sediments. Tidal streams affected sediment grading in the East Kyle. Here coarser and sandier sediments supported beds of brittlestars Ophiothrix fragilis and Ophiocomina nigra and the infauna included the heart urchin Echinocardium cordatum and the burrowing holothurian Labidoplax digitata. Two rare species were found in Loch Goil; the holothurian Ocnus planci and the tunicate Styela gelatinosa. The latter is a new British record and therefore assessed as of international conservation importance. In total 6 community types and 13 species have been assessed to be of regional, national or international conservation importance. Records currently considered sensitive have been removed from this dataset.