A visit to Loughrigg Fell

Lily_Tarn_Loughrigg_May15

Looking east across Lily Tarn, Loughrigg Fell, near Ambleside in Cumbria, May 2015.

I was in the Lake District earlier this week, teaching a course at the Freshwater Biological Association (of which, more later). En route, I stopped off at Ambleside, and climbed up onto Loughrigg Fell in search of algae. Why here? Well, this was one of a small number of locations identified as an “Important Plant Area” (IPA) for freshwater algae.   IPAs are an initiative of the charity Plantlife as a way of identifying those areas of the country of greatest botanical importance.   The problem we have with freshwater algae is the strong tradition of recording that is central to understanding distributions of organisms is less well established for freshwater algae than it is for many other groups (see “A “red list” of endangered British diatoms?”).   This, in turn, probably links back to the small number of amateurs interested in the microscopic world. Competent amateurs form the backbone of recording networks for much of the UK’s flora and fauna.

The desmids are one of the few exceptions to this generalisation, and the freshwater algae IPAs are largely based on the careful observations of one expert amateur, David Williamson. Loughrigg Fell was one of a number of sites that fell out of an analysis of his data, as a large number of species of desmid have been recorded from here, including a few that have rarely been recorded elsewhere.

Euglena_mutabilis_Loughrigg

Euglena mutabilis, from a Sphagnum pool on Loughrigg Fell, close to Lily Tarn, May 2015. Scale bar: 10 micrometres (= 1/100th of a millimetre).

However, the most distinctive taxon that I found in the first sample I looked at (from a squeezing of Sphagnum living in a boggy pool near Lily Tarn) was not a symmetrical and sedate desmid (see “Hunting for desmids in Upper Teesdale”) but a wriggly and squirming alga that I recognised as Euglena mutabilis.   When I was teaching at university in Nigeria, I used to set my students an essay “Euglena: plant or animal? Discuss”.   The Euglena that I found in this boggy pool on Loughrigg had distinct green chloroplasts for photosynthesis, but not all species in this group have these. Some, instead, obtain their nutrition from carbon compounds dissolved in the water. What is more, I expect “plants” to have rigid cell walls whereas Euglena has a flexible “pellicle” (made of protein, not cellulose) which enables the organism to constantly change its shape, and to move around.   Most Euglena species have a flagellum; E. mutabilis is an exception and the photographs and video show characteristic euglenoid movement (“metaboly”) as the cell changes shape and the cytoplasm streams in to fill this up.   Of course, modern biologists do not really hold with a rigid distinction between “plants” and “animals” but it was still a useful way to get undergraduates thinking.

Euglena mutabliis is a very characteristic species of acidic environments, found not just in Sphagnum bogs, but also in acid mine drainage, where the pH can be as low as 2.0.   Living in such acid environments creates considerable problems for organisms so E. mutabilis has attracted much attention from people wondering how it copes.   The inside of all cells tends to be more-or-less neutral and most enzymes are optimised to work best under such conditions.   However, cell interiors also naturally have a negative charge, which means that hydrogen ions – the ‘active ingredient’, if you like, of acidity, naturally flow into cells. The evidence that we have shows that the pH inside E. mutabilis cells adjusts as the pH outside changes, though it is never as acid as conditions outside the cell. This must mean that the cells are using a lot of energy pumping the unwanted hydrogen ions out.

There are some great views from Lily Tarn, though the clouds were quite low during my visit.   Windermere spreads out to the south, and I could just make out Wray Castle on the west shore, the original home of the Freshwater Biological Association.   To the north, I could see the flanks of Helvellyn when the clouds parted, and the track that led up to the Fairfield Horseshoe.   The ground falls away steeply to the east of Lily Tarn, and you can look down into Ambleside itself, only a couple of kilometres away.   And that’s where I’m heading for my next post …

Reference

Brodie, J., John, D. M., Tittley, I., Holmes, M.J.,Williamson, D.B. (2007) Important Plant Areas for algae: a provisional review of sites and areas of importance for algae in the United Kingdom. Plantlife International, Salisbury, UK.

Hargreaves, J.W. & Whitton, B.A. (1976). Effect of pH on the growth of acid stream algae. British Phycological Journal 11: 215-223.

Hargreaves, J.W., Lloyd, E.J.H. & Whitton, B.A. (1976). Chemistry and vegetation of highly acidic streams. Freshwater Biology 5: 563-576.

Pentecost, A. (1982). The distribution of Euglena mutabilis in Sphagna, with reference to Malham Tarn North Fen. Field. Studies 5: 591-606.

 

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John Walter Guerrier Lund (1912-2015)

I was sorry to hear that John Lund died a few days ago.   I first encountered him in a second year undergraduate lecture on succession, when his pioneering work on seasonality in lake phytoplankton was used as an example.   He was appointed to the Freshwater Biological Association in 1944 and produced a series of important papers on the ecology of the phytoplankton based on his observations in Windermere and nearby lakes over the next decades.   I also remember a paper he wrote for the now sadly defunct journal Field Studies, which demonstrated a broader interest in the natural history of freshwater algae. And, in 1996, along with his wife, he published a marvellous book, Algae: their Microscopic World Explored.   She provided the pictures, he wrote the text, drawing on his extensive experience of all algal groups.   You can find more details of his life at the Fritsch Collection website.

Others will write full obituaries in due course. I only met John on a few occasions but the last visit was very memorable.   I was searching for a freshwater Chrysophyte called Phaeodermatium, a relative of Hydrurus foetidus (see “A brief excursion to Norway”).   In their book, John Lund had explained that it thrives in the colder months of the year and usually disappears in summer.   He also commented that it was found in the stream that flowed through his garden.   As it happened, I was going to a meeting in Windermere at about this time and I thought that I could take this opportunity to visit John Lund and collect a sample from his garden.   I called ahead, arranged a time to visit and, at the appointed time, my colleague who had driven me over from Durham dropped me off at his old slate cottage, Ellerbeck, on the north side of Ambleside.   My colleague was going to wait in Ambleside for half an hour or so until I joined him with my sample.

John, at this time, was in his late 90s, physically frail and almost blind, though his mind was still sharp and he was as courteous as ever.   He not only welcomed me to his house but also announced that he would join me on the excursion through his extensive garden to find the alga.   We made our way very slowly along the paths towards the stream, talking about mutual acquaintances.   At one point he stopped, lifted his head and asked me: “are we close to the Magnolia tree?”   I said that we were.  Then, rather wistfully, “it’s very beautiful at this time of year isn’t it?”   And then we moved on again towards the stream.   I was due to be at a meeting in the very near future and took advantage of John’s lack of sight to discretely text my colleague to tell him to go on without me.

We reached the stream eventually, and I stepped in to collect my samples. He had mentioned that Phaeodermatium formed crusts on rocks and stones that could become so thick that the rocks were slippery to walk on. The rocks were certainly slippery but, when I looked at my haul under my microscope a day or two later, the sample was dominated by Diatoma mesodon not Phaeodermatium. We then made the slow journey back through the garden to his house, where I said goodbye and walked into Ambleside where, in the absence of any local taxis, I had to wait for the next bus to Windermere, eventually arriving at my meeting about an hour after it had started.

His house, Ellerbeck, incidentally, gave its name to the monotypic diatom genus Ellerbeckia.   John Lund was married to Hilda Canter-Lund, in whose memory the Hilda Canter-Lund photography prize was established (see “Hilda Canter-Lund photography award 2013 winner”.

References

Canter-Lund, H. & Lund, J.W.G. (1995). Freshwater Algae: Their Microscopic World Explored. Biopress, Bristol.

Lund, J.W.G. (1961). The algae of the Malham Tarn district. Field Studies 1: 85-115.