Marine Biodiversity Data Portal - NI

Bruce's Cave, Rathlin Island.

[Site list for year 1987]

Survey number: 555 Event number: 19870526/24 Date: 1987-05-26 GPS: 55.30100,-6.16800. Depth: 3.5 to 0.2 m. [ View map ]

Site Description: A large deep sea cave near the NE point of Rathlin Island, beneath the east lighthouse. The walls of the cave are vertical with occasional ledges near the low water level. The roof of the cave is about 18 m above low water, and has razorbills and guillemots nesting on ledges. The cave channels swell and is very exposed, especially towards the mouth. The end has a small shingle beach about 150 m from the mouth and the cave is uniformly about 6 m wide. Towards the mouth, the illumination is gloomy and the littoral zone has a total cover of encrusting algae and little else. The intertidal has a blanket of corallines extending into the splash, and the upper splash has a total cover of Hildenbrandia with some Hydropunctaria maura (originally recorded as Verrucaria maura) extending 8-10 m up the vertical walls of the cave. Some Patella, Chthamalus, littorinids and Mytilus were present on ledges and deep in crevices. A transect was done across a narrow ledge near the mouth of the cave, having a typical community. The algal cover gradually diminished to nothing towards the back of the cave, probably due to the low light conditions? Entry to the cave should only be attempted when the sea is very calm.