Scottish Natural Heritage (SNH) will this month begin a new long-term monitoring programme of environmental conditions in saline lagoons in the Uists.
SNH has invested in six data loggers which record a number of environmental variables every five minutes. These devices can be left in place for up to a year before they are retrieved and data downloaded.
Stewart Angus, SNH’s coastal ecology adviser, will visit North Uist in the coming weeks and will initially distribute the devices around the lochs at Clachan. They will be run for two tidal cycles there before they are moved to their home for the next year in Loch an t-Sruith Mhoir.
Mr Angus confirmed: “The Uists have some of the finest lagoons in Europe and Loch an t-Sruith Mhoir is one of the best of all supporting a number of unusual species that only live in a few lagoons – lochs that have both fresh water and sea water inflow.”
He explained that SNH’s monitoring of the Uists is similar to constructing a large jigsaw. Knowing how salt water functions in the islands is critical to understanding how rising sea levels will affect coastal habitats.
He added: “The data loggers will be moved around, gradually completing a few more pieces of the jigsaw, and adding to our understanding of the area. Our work in 2005 revealed there are complex relationships between surface water and ground water in the Uists that are extremely important in the context of rising sea levels.
“However, our understanding of these lochs is so poor that we do not even know what the tidal range is, though it is believed to be in the order of 50cm. Water levels change with the tide by just 50cms compared with the usual four metres on open Uists coats. The loggers will directly record temperature, depth, conductivity, and pH and will also give salinity via specialist software.”
Mr Angus stressed that though the equipment would be left in the open it will be placed in such a way as to minimise storm damage. Though there was just one boat on the loch it is operated by the local estate which would warn anglers about the location of the devices.
He added: “We are asking people not to approach the devices which resemble fluorescent light tubes if they come across them as this will disrupt the readings.”