Lucky heather …

maa_water_oct16_2

The interior of Shetland’s Mainland is rugged and remote and almost completely lacking basic tourist infrastructure such as footpaths that most hikers take for granted.  We located the approximate position of our destination on the skyline using our map then set off across heather-covered blanket bog, slithering down peat hags and across small streams until we reached our destination.  This was not a good time to find that I had left an important part of my sampling kit back in the car.

I searched every pocket of my cagoule and rucksack but I could not find my bag of toothbrushes.   These are the basic sampling tool of every diatomist, perfect for removing most algae growing on the surface of submerged stones.   Yet here I was, in one of the most remote corners of the country,  facing a beautiful small loch, but without any means of collecting a sample.   Jon, my co-worker on this trip, looked around us: “can’t you use a piece of heather?”

And so that is what I did: I pulled up a few shoots of heather, gripped them between two fingers and used these, toothbrush style, to clean the brown film off the surface of stones.   I picked out a few leaves and stems out of the final suspension and poured this into my sample bottle.   Problem solved.

sampling_diatoms_with_heath

Using a piece of heather (Calluna vulgaris) to sample diatoms from a loch in Shetland, October 2016.  The top photograph shows Lamba Water, Mainland (photographed above), during the same sampling trip.

Several of the stones that I picked up from the littoral zone of Lamba Water had slippery, gelatinous tufts which, when examined closely with the naked eye could be seen to be made of bead-like filaments which I recognised to be the red alga Batrachospermum (see “Algae … cunningly disguised as frog spawn”).    Under the microscope, the beaded appearance resolved into tufts of branches arising from a single main axis which, at low magnification, looked like a bottle brush.   Most of my previous encounters with this genus have been in hard water but Lamba Water has relatively soft water (alkalinity: 7 mg L-1 CaCO3; conductivity: 117 mS cm-1) and a slightly acid pH (6.4) due to the surrounding peat which stained the water a dark brown colour.   Browsing through my Flora, I did notice that many of the species listed do appear to have very broad ranges for conductivity that suggest a low sensitivity for rock type compared to other types of algae.   I would not like to make too much of this as the data in the Freshwater Algal Flora of the British Isles are relatively sparse, but it is something that would be interesting to pursue in the future.

batrachospermum_lambawater_

A tuft of Batrachospermum on a submerged cobble in the littoral zone of Lamba Water, Shetland Isles, October 2016.  Scale bar: approximately 1 centimetre.

batrach_lamba_nov16_3

magnification; right hand image at 400x (scale bar: 20 micrometres (= 1/50th of a millimetre).

One of the characteristics of Shetland is a very diverse geology packed into a relatively small area and the following day’s excursions took us to a very different lake on the other side of Mainland.   This was Loch of Girlsta, much deeper than Lamba Water (it is the only loch on Shetland with a population of Arctic Charr, I understand) and influenced by a narrow band of limestone (although most of the catchment seems to be the standard Shetland blanket bog).   By this time, we were having to contend with rain as well as strong winds and our time on site was limited.  I did, however, have a chance to spot some dark brown hemispherical colonies, mostly 3-4 mm in diameter, on some of the submerged stones.  Although the hemispherical colonies first made me think of Rivularia, when I was back in warm and dry conditions and had a chance to look at it under my microscope, it turned out to be Tolypothrix, the cyanobacterium that we last encountered in Ennerdale Water (see “Tales from the splash zone”) which is, chemically, quite similar to Loch of Girlsta, though perhaps with less peat in the catchment.   Both are in catchments with so little human influence that algae need to resort to nitrogen fixation in order to obtain the nutrients that they need to grow.

As an illustration of the extraordinary geological and ecological diversity that we encountered in such a small area, Loch of Benston, the final loch that we visited, was almost entirely underlain by limestone, and had extensive Chara beds.

girlsta_tolypothrix_colonie

Colonies of Tolypothrix cf distorta (arrowed)) on rocks in the littoral zone of Loch of Girlsta, Mainland, Shetland Isles, October 2016. 

girlsta_tolypothrix_oct16_

Microscopic view of a false branch of Tolypothrix cf distorta from Loch of Girlsta.  Scale bar: 10 micrometres (= 100th of a millimetre).

Back on the mainland (the British mainland, that is, rather than Shetland’s Mainland), it was the autumn colours that struck me, after a few days north of the treeline on Shetland.   The drive back south from Edinburgh took me through the wonderful array of brown, red and yellow hues of the Borders and Durham, itself, always looks spectacular at this time of year.   The diatom samples that I collected with those bunches of heather now need to be processed and, I’m sure, there will be more tales from the northern isles to tell once I’ve had a chance to look at these.

durham_riverbanks_oct16

Autumn colours on the Durham riverbanks, October 2016.

 

Advertisements

Blown away by Shetland

st_ninians_isle_oct16

Sometimes, my work takes me to places where my good intentions to highlight the importance of the microscopic world are swept away by the sheer grandeur of the landscape around me.  That happened last week when a sampling trip to the Shetland Islands ended sooner than expected, leaving me just enough time to hire a car and explore the UK’s most northerly archipelago before heading back to the airport.

We worked in the interior of Mainland, the largest of the islands, where the rocks were mostly covered by a thick layer of peat, amidst strong winds and periodic heavy showers.  When there were breaks in the clouds, the low sun imbued the landscape features with intense hues for short periods before the strong winds blew in more clouds.   Walking across the peat moorland was tiring and, when I had time to myself, I was ready for a change.

When I collected my hire car from Lerwick, I was given careful instructions on how it should be parked in gale force conditions such as these.   Park it facing away from the wind and a gust might pull the door from its hinges as soon as you opened it.  I got the impression, from the way that this was carefully explained to me, that this was something that happened quite regularly to tourists on the island.   Suitably briefed, I headed north across Mainland, across a narrow isthmus to Northmavine and past small settlements that looked more Scandinavian than Scottish in appearance clustered around sheltered bays.  My destination was Esherness, at the far north-western corner of the Shetlands, where waves, ten or more metres high, crashed against cliffs made of hard volcanic rocks that stretched away into the distance.   I was completely alone here, dwarfed by the landscape, buffeted by the wind blowing in off the Atlantic, but exhilarated by the experience.

eshaness_oct16_1

Sea cliffs at Eshaness, Northmavine, on Shetland, October 2016.  The upper photograph shows waves breaking on the tombolo connecting St Ninian’s Isle to Mainland.

The worst of the rain passed through overnight, but the strong winds persisted the following morning when I diverted from my drive back to the airport to the south-western coast where I stood on a beach looking across the waves to St Ninian’s Isle.   The island is separated from the mainland by a 500 metre “tombolo” – a narrow sand spit that just about stood proud from the sea although, today, the wash of the waves from both sides often met in the middle, disabusing me of any notions that I had time to get out and back with dry clothes and enough time to make it to Sumburgh airport in time to catch my flight.

My one and only souvenir from the trip was a bottle of gin from the Shetland Distillery Company, based on Unst, the most northerly island in the group.  The attraction of their “Ocean Scent” gin to me was that they used bladder wrack (Fucus vesiculosus) as one of the botanicals although freaks who expect to the scent of seaweed to waft out of the bottle on opening will be in for a disappointment.  The gin has the depth of flavour that one expects from a good craft gin, but the wrack is just one of a number of botanicals whose essences blend together in the final spirit.   Having tried this gin, however, I’m also intrigued to try the Isle of Harris gin that features sugar kelp (Saccharina latissima)as one of its botanicals.  I just need to find an excuse to visit …