Clashmore Quarry, Assynt: 2016
Ian M. Evans
Article originally published in The Highland Naturalist 13, March 2017, pp34-37. HBRG
I made six visits to this local site between May and November 2016, with a further one on the first day of 2017. Some were brief, just to check on seasonal progress, others were longer, with specific objectives. I have summarised the more interesting findings by date.
On 1st May, a brief sortie yielded two spring-flowering plants not seen before, lesser celandine Ficaria verna and field wood-rush Luzula campestris. Aerial parts of the former soon die back and confirmation of the latter requires the measurement of the anther:filament ratio, so both were missing from lists made later in the year.
I returned for a walkabout on 12th June, when I added a species to the (predictably) short list of birds, wheatears perched on the power supply wires along the northern edge of the site. Spring-brood green-veined whites were flying, as were small heaths. Two of the earlier dragonflies were flying in tandem, large red and common blue damselflies, and there were occasional four-spotted chasers moving at speed over the pools. One of few rove beetles that may be reliably identified in the field, Staphylinus erythropterus, was hunting over open areas; it is large (up to 18mm), with reddish elytra and paired patches of golden hairs on the rear part of the exposed abdomen.
Botanical fieldwork, on the north coast of Sutherland, took precedence during June-August, so I wasn’t there again until 28th August. Second-brood green-veined whites were about, but it was the numbers of the later-flying dragonflies that were really impressive. I gave up trying to count the common emerald damselflies and black darters at 50+ of each, many paired and egg-laying, and there was also a common hawker flying fast over the large pool, a new species for the site. Some casual stone-turning added the common shiny woodlouse Oniscus asellus to the invertebrate list.
Conscious of my neglect, I was back on 10th September with a small pond-net. There were active groups of whirligig beetles on the large pool, but they successfully evaded capture by making for deep water or, more surprisingly, diving. However, I did net some lesser water-boatmen, which included one of the larger species, Corixa punctata. I also came up with some green balls of jelly several centimetres in diameter, which I recognised as colonies of the peritrich ciliate Ophrydium. Under a high power microscope tiny contractile individuals may be seen embedded in the surface of the balls, accompanied by the symbiotic green ‘algae’ or zoochlorellae which give them their colour.
I was able, with a grapnel, to haul out of deeper water in the large pool a small sample of a ‘willow-leaved’ pondweed that I had noticed on an earlier visit, but had been unable to reach. This proved to be red pondweed Potamogeton alpinus, a species of still or flowing water, neutral or slightly acidic, which is most frequent in northern England and Scotland, and occurs occasionally in Assynt lochs. More surprising, however, on the well-vegetated western side of this pool, was a small stand of the unmistakeable ‘bottle-brush’ aerial stems of mare’s-tail Hippuris vulgaris. This is a rare aquatic in Assynt, previously known from just five sites in the north-west and south-east corners of the parish. One of these sites is Loch na Claise, less than a kilometre to the south of the quarry, but I am sure I would have noticed it, if then present, when visiting the quarry during 2015. The species has stout creeping rhizomes, with which it spreads locally, but it is presumably dispersed over longer distances by its small seeds, perhaps via the mallard which occasionally visit the quarry pools. I also made the unsurprising addition of meadow pipit to the bird list for the site.
I tried on this occasion to get a definite name for the giant-rhubarb Gunnera sp. on the side of the quarry (mentioned in the previous article), by collecting a single leaf and photographing its fearsome armature of spines. The account of the two species in Clive Stace’s New Flora of the British Isles (2010, p.123) would suggest Gunnera tinctoria, which he records as ‘often self-sown’ and ‘naturalised in scattered places’.
Learning, from an old friend, that research in Gunnera was being conducted at the Royal Horticultural Society’s Garden at Wisley, I contacted their Horticultural Taxonomist Dr Kalman Konyves. He replied that the ‘morphological part of our project is still to be finished’, and regretted that he ‘did not know any characters that are reliable enough to identify the two species’, adding that ‘we found this aspect of our project quite challenging’. Giant-rhubarbs may be quite widespread as self-sown escapes from cultivation in the north of Scotland, since we had seen some plants on a cliff near Strathy in August. However, it does not look as if we shall get a definite name for the Clashmore Quarry plant, or any others, in the immediate future.
I returned on 19th September with a more substantial pond-net on an extended handle, and this time managed to capture one of the elusive whirligig beetles. Members of the group are readily recognisable, not only by their behaviour and streamlined profile, but also because they have two pairs of eyes, for seeing in both water and air. However, identification to species can be quite challenging. Not in this case, thankfully: small (5mm), with a longitudinal seam down the pronotum and yellow beneath – a female Gyrinus minutus, widely recorded in Assynt. Despite wielding the pond-net with vigour, I did not catch any other water beetles, and realised, with some surprise, that I have not done so on any other occasion.
I did manage to net some more lesser water-boatmen, adding Sigara semistriata to the tally of this group; it is a small corixid, mainly northern in its distribution, but with only a few scattered records from the Highlands. I also captured an adult palmate newt and a well-grown larva of the common hawker dragonfly. In the shallows of the large pool I noticed slender stems of one of the bladderworts, which, under the microscope, proved to be lesser bladderwort Utricularia minor, adding to the already good list of aquatics. Whilst a single bladder was under the microscope, I spotted a water bear or tardigrade crawling on its surface.
A sample of some rather sludgy material from one of the smaller pools added water mites and some water fleas (small cladoceran crustaceans) to the aquatic invertebrate list. I attempted to identify one of the latter, using an FBA key dating back to 1941, and was very pleased when it came out as a species of Simocephalus, probably S. vetulus. Given the age of the key, I checked my identification on the internet. Some individuals were carrying live young inside their carapaces, and a dead one was being scavenged by tiny nematode worms. Water fleas are an important part of the food web in freshwater habitats and are collected elsewhere by aquarists for use as fish food. NBN has, however, no records for the group from the Highland area.
More stone-turning away from the pools yielded a few terrestrial invertebrates, including the ground beetle Nebria salina, a species with a good scatter of records across the Highland area, but none from this 10km square. I also had the almost ubiquitous common rough woodlouse Porcellio scaber and the equally widespread netted field slug Deroceras reticulatum. All relatively small beer, but helping to build up a picture of the biodiversity of the site.
My last visit of 2016 was on 10th November, with a special fine-meshed net for desmid samples, which I later processed and sent off to David Williamson (see previous article, pp.20-21). He later reported that the samples had been a ‘bit thin’, but, after a prolonged search under the microscope, that from the large pool had yielded 17 species, seven of which were new to the site, and one of the smaller pools just five, two of which were new. The variety new to the British Isles collected in 2015 had recurred, together with a related one, Closterium kuetzingii var. vittatum, which he described as ‘quite rare’ in Europe as a whole. The desmid tally for the site is now some 45 forms.
Rather more obvious was the large shiny fruiting body of a gill fungus on a cow pat. Bruce Ing kindly identified this from a photograph (not possible with many species) as the dung roundhead Panaeolus semiovatus; common enough, but worth noting since there are virtually no records of fungi from the site.
The sole record of a mammal from the quarry was a sighting of a pine marten back in the 1980s, and I tackled this deficiency on 1st January 2017. In the base of some grass tussocks on a bank, I found, as hoped, the runs of field voles, with characteristic piles of green droppings. Encouraged, I then searched larger tussocks of soft rush Juncus effusus elsewhere on the site, and in the bottoms there were more runs, droppings, and another give-away, short sections of stems of the rush, neatly chopped to length.
So, a further year’s visits have yielded some useful records for this intriguing area. I should perhaps devote more attention, during 2017, to the invertebrates, both aquatic and terrestrial, and also to the fungi. There must be some more water beetles in the pools, and I wonder if it would be feasible to run a moth trap tucked away in a corner for a few nights in the summer?