Quinag Lochs Project A Study of Aquatic Invertebrate Communities Quinag Lochs Project By Gwenllian M. Richards Assynt Field Club May 2012 Funded by Culag Community Woodland Trust Ltd, John Muir Trust, Assynt Field Club, Substance (Assynt Angling Research), Scottish Wildlife Trust, and the Sutherland Partnership Environmental Fund, which was supported by Leader and Scottish Natural Heritage. Cover illustration: Loch Bealach Cornaidh, looking south from Sail Garbh email: [email protected] 1 Contents Abstract................................................................................................................................3 Introduction..........................................................................................................................3 Lochs....................................................................................................................................4 Sample Sites.........................................................................................................................5 Methods Used......................................................................................................................7 Lochan Feoir........................................................................................................................9 Lochan an Duibhe..............................................................................................................17 Loch Coire Riabhach.........................................................................................................24 Lochan Bealach Cornaidh..................................................................................................32 Unapool Burn Lochan 1 (West).........................................................................................40 Unapool Burn Lochan 2 (Middle).....................................................................................47 Unapool Burn Lochan 3 (East)..........................................................................................53 Loch Airigh na Beinne.......................................................................................................59 Interpretation of Results.....................................................................................................68 Bibliography......................................................................................................................75 Acknowledgements............................................................................................................76 2 Abstract Eight lochans on the John Muir Trust property at Quinag were sampled for aquatic invertebrates in the summer of 2010. The sites were chosen for their varying geology : one on Cambrian quartzite, six on Torridonian sandstone and one on Lewisian gneiss. Their pH values ranged from 5.3 to 7.2. Groups identified to species included: Odonata (8 spp.), Trichoptera (21 spp.), Hemiptera (2 spp.), Coleoptera (5 spp.), Ephemeroptera (5 spp.), Plecoptera (4 spp.), Bivalvia (3 spp.), Gastropoda (1 sp.), Hirudinea (1 sp.), Megaloptera (1 sp.). The number of groups and species represented in the samples varied from 12:25 (Loch Bealach Cornaidh) down to 8:10 (Unapool Burn Lochan 3 East). The relative abundance of particular groups appears to be related to pH, altitude, substrate and the amount of emergent vegetation. Introduction The Quinag Lochs Project was a study of aquatic invertebrates in several lochans around the base of the 808 metre mountain, Quinag, in the parish of Assynt, Sutherland. It was a follow-up to the Little Assynt Lochs Project which also recorded aquatic invertebrates in a group of lochs on the Little Assynt Estate, in the summer of 2010. This latter study was carried out by Caroline Bowes for the Culag Community Woodland Trust who own the estate. While the Little Assynt lochs all lie on Lewisian Gneiss, the eight lochs sampled around Quinag were chosen because they lie on three different base rocks: Lewisian Gneiss, Torridonian Sandstone and Cambrian Quartzite. The aims of the project were to give an indication as to what species might be present and whether any comparison could be made between the lochs on different rock types. The Unapool Burn lochans were chosen because of their small size and a previous record of Dytiscus lapponicus. The 3,699 hectare Quinag Estate is owned and managed by the John Muir Trust who partially funded the project which took place in July and August 2010. Other funders were the Culag Community Woodland Trust, the Scottish Wildlife Trust, Sutherland Partnership, Substance (Assynt Angling Research) and the Assynt Field Club. 3 Lochs The lochs chosen were: 1. Lochan Feoir on Cambrian Quartzite. 2. Lochan an Duibhe on Torridonian Sandstone. 3. Loch Coire Riabhach on Torridonian Sandstone. 4. Lochan Bealach Cornaidh on Torridonian Sandstone. 5. Unapool Burn Lochan 1 (West) on Torridonian Sandstone. 6. Unapool Burn Lochan 2 (Middle) on Torridonian Sandstone. 7. Unapool Burn Lochan 3 (East) on Torridonian Sandstone. 8. Loch Airigh na Beinne on Lewisian Gneiss with basic dykes. 8 7 5 6 Unapool Burn Lochans 4 3 2 1 © Copyright Ordnance Survey 4 Sample Sites Samples were taken at 38 different sites altogether. Loch Grid Ref. Site Lochan Feoir NC 23042522 A Lochan Feoir NC 22822526 B Lochan Feoir NC 22802504 C Lochan Feoir NC 22772523 Inflow Lochan Feoir NC 22802505 Outflow Lochan an Duibhe NC 21762555 A Lochan an Duibhe NC 21942546 B Lochan an Duibhe NC 22072550 C Lochan an Duibhe NC 21892554 Inflow Lochan an Duibhe NC 21712555 Outflow Loch Coire Riabhach NC 21692597 A Loch Coire Riabhach NC 21852592 B Loch Coire Riabhach NC 21942594 C Loch Coire Riabhach NC 21982590 Outflow Lochan Bealach Cornaidh NC 20682811 A Lochan Bealach Cornaidh NC 20912805 B Lochan Bealach Cornaidh NC 21072813 C Lochan Bealach Cornaidh NC 20642824 Inflow Lochan Bealach Cornaidh NC 21112805 Outflow Unapool Burn Lochan 1 (West) NC 22972923 A Unapool Burn Lochan 1 (West) NC 22952922 Inflow Unapool Burn Lochan 1 (West) NC 23032921 Outflow Unapool Burn Lochan 1 (West) NC 22982919 B Unapool Burn Lochan 1 (West) NC 23012922 C Unapool Burn Lochan 2 (Middle) NC 23052925 Inflow Unapool Burn Lochan 2 (Middle) NC 23072923 A 5 Unapool Burn Lochan 2 (Middle) NC 23082926 B Unapool Burn Lochan 2 (Middle) NC 23102924 C Unapool Burn Lochan 2 (Middle) NC 23092919 Outflow Unapool Burn Lochan 3 (East) NC 23322937 A Unapool Burn Lochan 3 (East) NC 23282935 B Unapool Burn Lochan 3 (East) NC 23202934 C Unapool Burn Lochan 3 (East) NC 23232937 D Loch Airigh na Beinne NC 21733116 Outflow Loch Airigh na Beinne NC 22003095 Inflow Loch Airigh na Beinne NC 21833106 A Loch Airigh na Beinne NC 22043096 B Loch Airigh na Beinne NC 21973112 C 6 Methods Used As far as possible, the sampling methods followed those of the Little Assynt project, but with some small modifications. A standard 1mm. mesh dip net was used for sweeping underwater and emergent vegetation and for kick sampling. If stones were present in the substrate, they were lifted and hand searched for clinging organisms. A total of 3 minutes sampling was done at each site. Selection of Sample Sites Locations were chosen to represent various habitats present in each loch. Inflows and outflows were sampled 10 m. from the loch edge. pH and temperature were measured at each place using a Hanna waterproof pH tester with replaceable electrodes ( Model Hi98127). pH readings were automatically temperature compensated and were accurate to + or - 0.1 pH. Grid references were made with a Garmin e Trex H personal navigator. Plant species in an area 5 m x 2 m next to the sample site were recorded for percentage cover or presence. Names used were as those in the Flora of Assynt (2002). Sample Collection Dip Net - Kick Sampling. This method was used on loch bottoms of silt, sand and gravel. The substrate was disturbed with one foot and kicked towards the dip net, for 30 seconds at a time. The contents of the net were then tipped into a collecting tray with water from the area being sampled. Amphibians were returned to the loch. Larger specimens of the Odonata were placed in water in small universal tubes and the rest of the sample was poured into wide-mouthed polypropylene jars. Dip Net - Sweeping. The net was swept through underwater and/or emergent vegetation or fine sediment too deep to kick. Contents of the net were tipped into a collecting tray (containing water from the site) after every 15 second sweep. Specimens were treated as above. Hand Searching. As many stones as possible were gathered during the allocated period, placed in collecting trays and then examined for clinging organisms. These were transferred to universal tubes containing water from the sample site. If a mixture of sediment types occurred at a sampling location, then the 3 minute period would be divided up between the different methods. For example: 1 minute kick sampling, 1 minute netting plants, 1 minute stone searching. 7 Sorting and Preserving Samples The jars were stored in a cool place for no longer than 1.5 days and, in most cases, less than 12 hours. Small amounts of sediment and water were placed in a collecting tray and scrutinized with a magnifying glass under a lamp. Invertebrates were removed with forceps or a paintbrush and preserved in tubes of 70% alcohol. Identification Preliminary sorting of the specimens into groups was done with the aid of the Field Key to the Invertebrate Fauna of a Small Stony Hill-Stream by M. Redfern (1969) and the Reader's Digest Field