Species point records from 1978 NCC Loch Obisary survey

Published by:
Joint Nature Conservation Committee
Last updated:
15 December 2015
Topic:
Environment
Licence:
Open Government Licence

Summary

A preliminary survey was made of Loch Obisary, the largest brackish water loch in North Uist, Outer Hebrides. The loch has a single narrow connection to the sea, through which sea water enters at high tides. Salinity, temperature and depth measurements were taken throughout the loch and revealed the presence of a distinct halocline and thermocline in the north basin of the loch at about 4 m depth, neither of which were present in the south basin. The salinity of the water above the halocline in the north basin and throughout the south basin was 13 - 14 ppt whilst that below the halocline had a maximum of 28.5 ppt. Temperature decreased by approximately 1 degree Centigrade at the level of the halocline and rose again by approximately 0.5 degree Centigrade near the bottom of the loch. The flora and fauna were investigated both by diving and by shore collections. Two distinct communities of plants and animals were found in the loch: i) A 'freshwater ' marginal component consisting of freshwater euryhaline species and true brackish water species found above the halocline in the north basin and throughout the south basin of the loch. ii) A marine component consisting of marine euryhaline species numerically dominated by the red alga Phyllophora pseudoceranoides and the tunicates Ciona intestinalis and Ascidiella aspersa. Comparisons are made with other studies of brackish lochs and waters and it is concluded that Loch Obisary is an interesting and unusual example of this scarce habitat type.

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Additional information

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Added to data.gov.uk
2018-05-17
Access contraints
no limitations
Harvest GUID
0a2495e7-6ebf-4883-a5f3-2e3ab7b69dd8
Extent
Latitude: 57.56071656° to 57.51255964°
Longitude: -7.229043798° to -7.152251725°
Spatial reference system
Dataset reference date
2001-08-29 (publication)
Frequency of update
Responsible party
Digital and Data Solutions, JNCC (custodian)
ISO 19139 resource type
dataset
Metadata language
eng
Source Metadata
XML
HTML

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