Marine Biodiversity Data Portal - NI
Isle O'Valla (sediment), Strangford Lough.
Survey number: 555 Event number: 19860617/21 Date: 1986-06-17 GPS: 54.36083,-5.55100. Depth: 3.5 to 0.2 m. [ View map ]
Site Description: A sheltered shore in Strangford Narrows which has a very complex mixture of different sediment types amongst grass topped rock outcrops and rock ridges. The sediments include fine sand, mud, muddy sand, gravel and pebbles, and mixtures of these occur at different depths. The transect was situated between the Isle O'Valla and Cloghy Rocks and encompassed many of these sediment types. Backing was farmland used for grazing. The profile shows an uneven slope with a steep shingle upper shore, with Pelvetia and Fucus spiralis zones, a flat muddy shelf with few small Arenicola occurs beneath this, and the lower shore becomes steeper with fine and muddy sand with an irregular surface due to an abundance of Arenicola casts. The lower shore became stony with the sand being due to digging of Arenicola. Much water collected in the many small troughs between mounds. Many Lanice were present on the lower shore. Much of the shore was covered with algae which bound to the sand, notably brown filaments predominating the lower shore, and Enteromorpha in the upper. Ulva and Porphyra were also present. Stones and boulders occurred which had Ascophyllum, fucoids and Semibalanus attached. Digging revealed that stones and gravel occurred beneath the surface, the depth increasing towards high water. The flattened shelf in the upper shore had clay beneath the surface. The sediment contained Tellina, Macoma and Corophium.
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Species list (49 species recorded)
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