Clashmore Quarry, Assynt: multum in parvo

September 23rd 2016

Clashmore Quarry, Assynt: multum in parvo

Ian M. Evans

Article originally published in The Highland Naturalist, no.12, April 2016, pp 20-23. HBRG

Just north of the road to Stoer Head Lighthouse, in the township of Clashmore and parish of Assynt, West Sutherland, there is a small disused gravel quarry (NC036316). It lies about 1.5km from the coast of The Minch, at an altitude of 74m, between two rounded hills, Cnoc Breac to the west and Cnoc an Leothaid to the east. There is an isolated house to its west and a track leading north across moorland to Culkein Stoer on its eastern edge. Photo 1

Quarrying is thought to have started at some time in the late 1950s and probably ceased in the early 1980s when it had reached the track (pers.comm. Eachan Mackenzie).The original attraction of the site was a thick deposit of glacial sands and gravels lying on Torridonian sandstone bedrock.

Early in its history, a concrete loading bay for livestock was constructed, with associated fencing, at its western end. Much later, probably about 1994, when it was used briefly by contractors renewing the electricity supply to the area, some of the basement sandstone at the eastern end was dug out, yielding a deep pool; there are five other areas that hold water for some or all of the year.

The quarry is now bounded at its eastern end by steep banks exposing the sandy gravels which were its raison d’être. Its floor is littered in places with large erratic boulders, of a variety of rock types, also derived from the glacial deposits; elsewhere the floor is sandstone, still quite bare in places. The quarry proper is surrounded by undisturbed peat lying on the glacial deposits, bearing moorland vegetation on the northern and eastern sides and acid grassland to the south and west. Although I have driven along this road many times, I cannot remember sparing the quarry anything but a glance until 9th April of last year, when I decided to check its water bodies for frog-spawn. My diary records 15+ clumps, one of which was frosted, together with the remains of two female frogs that had been predated on their way to spawning; I also disturbed a common snipe.

Something about the largest pool must have impressed me, since four days later, on 13th April, I was back to sample it for desmid algae, which I send to an old friend in Leicestershire, David Williamson, who specializes in this group. These microscopic organisms are collected by running a plankton net through submerged vegetation, in this case a fine water plant that was abundant in the shallows. I knew this to be a stonewort, one of a group of green filamentous organisms, related to algae, that thrive in clean water, and a sample proved later to be the widespread species Chara virgata. This technique did indeed yield a reasonable desmid sample, which I posted off to David. I also accidentally netted two lesser water-boatmen of a widespread species of.‘base-deficient waters’ Hesperocorixa castanea, and a couple of small mayfly nymphs bearing seven pairs of elegant feather-like gills. These keyed out to the species Leptophlebia vespertina, known to fishermen as the Claret Dun, of which local records are few.

A little later, I received an excited telephone call from David; my sample had contained a desmid variety never previously recorded from the British Isles. Would I please obtain more material? Photo 2 This I did on 17th May, noting at the same time some of the early-flowering marsh plants around the pool, including marsh marigold Caltha palustris, cuckoo-flower Cardamine pratensis, marsh violet Viola palustris, and the cones of marsh horsetail Equisetum palustre. David’s discovery was eventually published in the Quekett Journal of Microscopy (Williamson, 2015), the abstract of his article reading ‘A rare variety of the desmid Closterium macilentum Brebisson 1856 has been found in West Sutherland.amongst a rich assortment of other desmids in an old quarry for the first time in the British Isles.’ The variety, substriatum, was originally described in a 1920 paper on the desmids of Finland, and David identified a further 35 desmids in the two samples.

About this time, I was looking for a new project to engage my interest during the summer, between distant botanical surveys. The site is only twenty minute drive from home, and the challenge of seeing what such a small area, just 130 x 50 m, might yield, appealed to me. Arbitrary boundaries were defined as the road to the south, the track to the east, a fence-line to the north and a nominal line at the edge of the disturbed area to the west.

The first systematic survey was done on 28th June, when Gordon Rothero and I spent an hour listing the bryophytes. Given the small size of the site, he recorded the very respectable total of 51 mosses and 13 liverworts. They ranged in size from large spiky cushions of the moss common haircap Polytrichum commune to tiny thalli of the liverwort known as crenulated flapwort Jungermannia gracillima, which is a ‘pioneer species of open base-poor rock’. The amount of water lying on the rocky floor of the quarry made it difficult to pick out smaller species, but Gordon did find some tufts of the awl-leaved swan-neck moss Campylopus subulatus, characteristic of ‘open gravelly or sandy places’, which was new to Assynt.

On 12th July, Gwen Richards and I spent 2½ hours logging the higher plants. The total was 124 species, a good haul for such a small area, and rather more than a day’s work yields in a 2km square on dourer ground elsewhere in West Sutherland. The flora is an interesting mix of relict moorland/acid grassland species, and newcomers that owe their presence to the use of the area as a quarry. Orchids were a particular feature, with a single spike of heath fragrant-orchid Gymnadenia borealis, another of heath spotted-orchid Dactylorhiza maculata ericetorum, at least ten spikes of lesser butterfly-orchid Platanthera bifolia, and some eighty deep purplish-red spikes of northern marsh-orchid D. purpurella spread throughout the wetter areas. Photo 3

The large pool had what appeared to be a single plant of common club-rush Schoenoplectus lacustris in its deepest part, other emergent aquatics in the shallows, such as least bur-reed Sparganium natans, and a fringe of marsh plants, including scarce species such as white sedge Carex curta, marsh cinquefoil Comarum palustre and marsh speedwell Veronica scutellata. At the edge of one of the shallower marshy areas we found skullcap Scutellaria galericulata, a species that does not usually occur quite so far from the shore-line in Assynt. Elsewhere in the quarry, much of the botanical interest was associated with open rocky areas, which harboured, amongst others, tiny plants of chaffweed Centunculus minimus and the small fern moonwort Botrychium lunaria. Perhaps least expected was a large plant of one of the giant-rhubarbs Gunnera sp. high on the southern bank. Four further species were added on other visits, including the uncommon slender rush Juncus tenuis.

The house to the west of the quarry belongs to long-time members of the Assynt Field Club, Roy and June Dunlop, who live in Greenock. They bought it in 1987 and have visited the area in most months of the year. Roy is a keen photographer and in August he sent me a compact disc bearing copies of colour slides he had taken in and around the quarry over the years, together with the originals and later digital images. I met up with Roy and June in late September, learned more about the history of the area from them, and have recently made a detailed list of the subjects of his photographs

This adds substantially to the animal life so far recorded from the site, including, for example, large red and emerald damselflies, black darter dragonfly, scotch argus and small copper butterflies, grey dagger, purple bar and six-spot burnet moths, and toads. Photo 4

On 29th August, Stephen Moran and I spent a couple of hours, on a slightly chilly afternoon, investigating the invertebrate life of the site. He deployed his D-vac, sweep net and beating tray, while I recorded his finds and also wielded a pond net. The results exceeded our expectations. So far, nearly 70 taxa have been identified; mostly listed in the appendix. They include representatives of nine orders of insects, two groups of arachnids, and a freshwater sponge; the sponge and some beetles have still to be named. Of particular interest were numerous examples of a tiny pselaphid beetle Reichenbachia juncorum, Photo 5 and a small black rove beetle Tachinus proximus; there appear to be no previous records of either from the North-west Highlands (on NBN Gateway). Stephen also found the mines, on skullcap, of the micro-moth Prochoreutis myllerana. Species photographed by Roy Dunlop, and ones noted by us on other visits in 2015, have been incorporated in the list below.

The final visit of the year was on 1st October, when lichenologist Dr Tony Fletcher and I spent an hour or so in the quarry. He has so far identified some 42 lichens from this visit, together with a lichenicolous fungus Abrothallus sp. He sampled some six microhabitats and the relative numbers of the species found by him in these is enlightening. They were, in descending order of richness: old fence-posts* along the northern edge (18), exposed rocks (13), the concrete of the old loading bay (7), heathland along the northern edge (4), bare earth and peat (4), grassland (2), with a few species occurring in more than one microhabitat. Probably the most interesting was Cladonia coccifera s.s.. This red-fruited member of a closely-related group of soil-inhabiting species is a rare, usually montane, species, confined to the Scottish Highlands.

Tony suggested that the variety of lichens on the site is almost certainly limited by its exposure to wind and rain; the west-facing sides of the old fence-posts, for example, were quite abraded. Also significant is the relatively short time, in terms of lichen colonization since rock surfaces in the quarry were uncovered. This last point was emphasised by the 18 species listed by him in a quick look at a south-facing field wall just across the road, which dates back to 1870s. Photo 6

In some eight hours of focussed recording we have now logged from this small site about 340 taxa, spread across the plant, animal and fungal kingdoms. Mind you, in three groups, desmids, insects and spiders, collecting in the field has been supplemented by many hours’ work with microscopes. It may be a sign of the times that the naturalists involved muster between them some 300 years of experience in their particular areas of expertise; then again, perhaps only such as us have the time for such frivolities. Fungi (other than lichens), most groups of invertebrates, and vertebrates (other than amphibians) have hardly been touched. We have just made a start on the insects and the freshwater habitats are largely unexplored, so there is plenty more to do.

Reference:

Williamson, D.B., 2015. The discovery of Closterium macilentum var. substriatum (Grönblad) Krieger in the British Isles. Quekett Journal of Microscopy 42, 511-514.

 

* Out of interest, fence posts have also been identified as an important habitat at Beinn Eighe NNR, somewhat to the south of Ian. See http://www.bbc.co.uk/news/uk-scotland-highlands-islands-15017589. These include the nationally scarce Mycoblastus affinis which was found on three posts http://www.snh.gov.uk/docs/A1499903.pdf.(Jeanette Hall)

 

List of animal life so far recorded:

Dragonflies and damselflies

Emerald damselfly (RD, July 1994, September 1995, August 2010) large red damselfly (RD, July 1995) common blue damselfly (12.7.15) blue-tailed damselfly (RD, June 1992; 12.7.15, 29.8.15), common darter (RD, August 2005, July 2006; 29.8.15), black darter (RD, August 2010)

Grasshoppers

Meadow grasshopper (29.8.15)

Mayflies

Claret Dun Leptophlebia vespertina (nymph, 13.4.15)

Caddisflies

Limnephilus vittatus (29.8.15)

True Bugs

Planthoppers: Anoscopus albifrons, Aphrodes bicincta, Arthaldeus pascuellus, Cicadula persimilis, Cicadella viridis, Deltocephalus pulicarius, Megophthalmus scanicus, Neophilaenus lineatus, Philaenus spumarius (all 29.8.15) Lacehopper: Cixius nervosus (m, 29.8.15) Jumping plant louse: Livia juncorum (adults, 29.8.15 – see galls) Mirids: Asciodema obsoletum, Closterotomus norwegicus, Cyrtorhinus caricis, Dicyphus pallicornis, Leptopterna dolobrata, Mecomma ambulans, Pachytomella parallela, Pithanus maerkeli, Plagiognathus arbustorum, Teratocoris saundersi, Trigonotylus ruficornis (all 29.8.15) Shorebug: Saldula saltatoria (parking place, 29.8.15) Aquatic bugs: Hesperocorixa castanea (13.4.15, 29.8.15), H. linnaei, Sigara scotti, Gerris odontogaster, Notonecta obliqua (all 29.8.15)

Butterflies & Moths

Green-veined white (RD, 2.8.14), small copper (RD, 1997), common blue (RD, 29.6.12), red admiral (RD, 12.9.10), small tortoiseshell (RD, August/September 1995), Scotch argus (RD, July 1994), meadow brown (RD, August 1984), small heath (12.7.15), six-spot burnet moth (RD, 26.6.12), fox moth (larva, RD, September 1994), grey dagger (larva, RD, July 1992), purple bar (RD, July 1995), twin-spot carpet (29.8.15), Prochoreutis myllerana (mines on skullcap, 29.8.15)

Beetles

Pterostichus niger (12.7.15), Harpalus latus (29.8.15), Haliplus ruficollis group, Reichenbachia juncorum (numerous), Micropeplus staphylinoides, Tachinus proximus [conf. RWJ Read],Tachyporus sp. (prob. dispar) Andrion (Sitona) regensteinense, Micrelus ericae, Protapion sp., Neocrepidodera transversa, Megasternum concinnum (all 29.8.15 unless otherwise stated)

Ants

Leptothorax acervorum, Myrmica ruginodis (29.8.15)

Flies

Geomyza tripunctata, Opomyza germinationis, Bibio pomonae, Eriothrix rufomaculata, Lonchoptera lutea

Sericomyia silentis (all 29.8.15)

Spiders

Xysticus cristatus (m, 2f), Pardosa sp.(imm), Tetragnatha extensa (all 29.8.15), Araneus diadematus (RD, no date), Larinioides cornutus (12.7.15), Meta segmentata, Ceratinella brevipes, Lepthyphantes tenuis, Allomengea scopigera (all 29.8.15)

Harvestmen

Nemastoma bimaculatum (29.8.15)

Amphibians

Common frog (RD, 10.8.09; 12.7.15), common toad (RD, toadlet July 1992, adult September 1994), palmate newt (juveniles, 29.8.15)

Birds

Common snipe (13.4.15), mallard (RD, 18.4.12)

Mammals

Pine marten (RD, 1980s)

Galls

Psyllid Livia juncorum on Juncus articulatus (12.7.15; adults on 29.8.15); fungus Puccinia urticata on Urtica dioica (12.7.15)

 

[The Highland Naturalist, no.12, April 2016, pp 20-23. HBRG]

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