No excuse for not swimming …

Lyons_lake_Hetton-le-Hole

Lyon’s Lake, Hetton-le-Hole, County Durham, May 2015.

After my sojourns in the Lake District and Latvia, I find myself back home in north-east England for a few days.   Whilst I was away, a small packet had arrived in the post, containing a sample of algae collected from a local lake. The bottles contained globules of bright green jelly-like material, with enough integrity to pick up with the fingers and they were intriguing enough for me to drive across one lunchtime to take a closer look at the lake where they came from.

Hetton Lyons Country Park is on the Permian Limestone plateau about 10 kilometres from where I live. It is on the site of a former colliery which closed in 1960 and the surrounding land has been reclaimed and partially converted to a country park.   The lake – probably a hectare or so in size – is used for angling and water sports, and the paths around the edge were busy with cyclists and dog-walkers.   It is on the edge of Hetton-le-Hole, a small town whose odd name refers to its location in one of the more sheltered parts of the plateau.

Aphanothece_stagnina_Hetton

A mucilaginous colony of Aphanothece stagnina (left) with (right) a microscopic view of the individual cyanobacterial cells embedded in mucilage. Scale bar: 25 micrometres (= 1/40th of a millimetre).

There were plenty of green algae around the margins of the shallow lake but, amidst this in a few locations, I could also see the small globules of the alga resting on the bottom which, like the colonies I had been sent, could easily be picked –up.    Under the microscope, these resolved into tiny cyanobacterial cells, mostly oval in outline and about five micrometres in diameter.   These belong to Aphanothece stagnina, a relative of the Gloeocapsa alpina, which we have seen in two other recent posts (see “The mysteries of Clapham Junction” and “Poking around amongst sheep’s droppings …”), albeit in very different habitats.

The word “cyanobacteria” alone is usually enough to make the manager of a recreational lake break out in a sweat.   Many cyanobacteria produce toxins that can affect the nervous system and the liver. This means that no contact water sports (swimming and canoeing, for example) can take place and dog-owners have to be warned not to let their pets drink from the water.   However, as far as I can tell from a brief search on the internet, Aphanothece is not a genus that is often reported in association with toxic blooms.   One less excuse, then, not to go wild swimming in a lake in north-east England on a breezy May afternoon …

More from Loughrigg Fell

As I do not pretend to great expertise on the desmids, I sent photographs of the specimens I collected during my visit to Loughrigg (see “A visit to Loughrigg Fell”) to Dave John who, in turn, passed them to David Williamson, to confirm their identities.   David Williamson co-authored the most comprehensive work on British desmids currently available, so I’m pleased to have his views on these specimens. To be honest, I was a little disappointed that I found so few desmids at a location from which so many had been recorded in the past. But then I am not a desmid expert, and may not have been looking in the best places.

Lily_Tarn_desmids_May15

Desmids from the margins of Lily Tarn, Loughrigg Fell, Cumbria, May 2015. a. Netrium digitus var. latum; b. Closterium dianae; c. Closterium dianae var. minus; d. Closterium directum (e. shows an entire cell of C. directum, photographed at lower magnification). Scale bar: 25 micrometres (= 1/40th of a millimetre).

I also found several cells of Eremosphaera viridis in squeezings from submerged Sphagnum at the edge of Lily Tarn.   At first, I thought that this was a colony of small cells but it is, in fact, a single large cell containing numerous small chloroplasts around the edge, giving it a very distinctive appearance. Like the desmids, it is a member of the Chlorophyta, or green algae, but it belongs to a different order, the Chlorellales rather than the Zygnemetales. That means that they are as different to one another as a rat is to a human.   By contrast, Euglena mutabilis, which we met in the previous post, is as different from a desmid as a human is from a slug.

I can recommend the desmids to anyone interested in microscopy.   They are, in many ways, much more amenable to amateur study than the diatoms. Desmids are generally about an order of magnitude larger than diatoms, which means that you can study them with a medium-power objective, rather than an expensive oil-immersion objective.   There is, in addition, a good English-language guide available whereas much of the key literature on diatoms is in German.   There are also plenty of sources of information available online. The only drawback with desmids is that their habitats are less widespread. Alternatively, I could put a positive spin onto this and remind you that a fascination with desmids will take you to some of our most spectacular landscapes.

Eremosphaera_viridis_Lily_T

Eremosphaera viridis from submerged Sphagnum at the margin of Lily Tarn, Loughrigg Fell, Cumbria, May 2015. Scale bar: 25 micrometres (= 1/40th of a millimetre).

Reference

Brook, A.J. & Williamson, D.B. (2010): A Monograph on some British Desmids. Ray Society, London.

Poking around amongst sheep’s droppings …

A couple of kilometres away from the stream featured in the previous post is an old quarry that we visit each year as part of this course (see “Nosing around for blue-green algae …”).   In a damp flush at the edge of the quarry floor, we found some patches of what looked, from a distance, like sheep droppings.   A useful strategy, shared by most of the human race, is to assume that anything that looks like a sheep’s dropping probably is a sheep’s dropping, and not to go prodding at this with a finger.   However, a curious soul in the distant past with a sense of adventure ignored this precept and discovered that a few of these were, in fact, growths of Cyanobacteria.   Most natural historians, wisely, focus their attention on more spectacular aspects of life on earth; however, a few of us have retained this childish instinct to poke at anything that looks like sheep’s droppings.

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Scytonema sp. from a flush at Whitbarrow Quarry, Cumbria, May 2015

A small part of one of these growths, teased out and mounted on a cover slip, reveals itself to have the characteristics of the genus Scytonema although, today and despite a long hunt, I could not find any filaments that presented themselves in a suitable position to photograph. The illustration below, therefore, is of a growth of Scytonema from another calcareous site in Cumbria. The Cyanobacteria is, you may remember, the modern name for the “blue-green algae” which is often confusing as many Cyanobacteria are not blue-green in colour.   What we can see here is a chain of cells (a “trichome”) which are surrounded by a thick sheath (“trichome” plus “sheath” equals “filament”, in Cyanobacteriological lore).   The sheath is a yellow-brown colour, due to a pigment called “scytonemin” which acts as a sunscreen, absorbing ultra-violet radiation and, in the process, obscuring the blue-green colour of the trichome within.

Scytonema_Sunbiggin_Tarn

Scytonema sp. from a calcareous flush at Sunbiggin Tarn, May 2005.   Scale bar: 10 micrometres (= 1/100th of a millimetre).

Two other characteristics of Scytonema are visible in the photograph.   Both the left and right hand pictures shows “false branches”: if the trichome breaks for any reason, either or both of the broken ends keep growing and break out of the filament. The left hand illustration is a single false branch and, just to the left of the branch you can see the distinct “heterocyst”, a cell where nitrogen fixation takes place.   The wall of the heterocyst is thicker than that of other cells, as nitrogen fixation can only occur in the absence of oxygen.

Walking back from the quarry towards the minibus, Allan pointed up at dark patches on the cliffs looming over us.   It was Gloeocapsa alpina, the same species that we met a short while ago in a cave on Malta (see “The mysteries of Clapham Junction …”).   The cliffs at Whitbarrow are, in effect, a vertical “desert” from the point of view of any organism that aspires to live there. These Cyanobacteria, with their ability to “re-boot” on those occasions when conditions are favourable for growth, have an advantage here.   One guesses that the damp climate of north-west England is slightly more forgiving than that of a Mediterranean hillside but it is still a tough habitat in which to survive.

Gloeocapsa_alpina_Whitbarro

Growths of Gloeocapsa alpina (arrowed) on the cliffs at Whitbarrow Quarry, May 2015.

Love and sex in a tufa-forming stream …

The reason behind my trip to the Lake District a couple of weeks ago was to teach a short course on identification of freshwater macroalgae with Allan Pentecost (see “Heatwave? What heatwave” and subsequent posts for more about last year’s course).   One of the sites we visit with the students is a small stream flowing off Whitbarrow, a Carboniferous limestone outcrop in southern Cumbria.   The bed of the stream is covered with tufa, formed from calcium carbonate precipitated from the water. We bring the students here because there is usually a good variety of cyanobacteria for them to learn to recognise in the field and to sample for later investigation in the laboratory.   Amongst these cyanobacterial growths, however, we also saw a few patches of green filaments on the stream bed, which we also took back with us.

Whitbarrow_tufa_stream_May1

Sampling Whitbarrow tufa stream in May 2015.

These filaments turned out to be growths of the green alga Oedogonium. You may remember that I wrote a post last year with the title “The perplexing case of the celibate alga …” in which I commented that Oedogonium, though a common genus in freshwaters, is difficult to identify to species because this requires the reproductive organs which are rarely seen in the wild.

Our population of Oedogonium, however, was fertile, and this enabled us (Allan, to be strictly honest, as he knows the algae of tufa-forming streams extremely well) to name it.   The images below show the distinctive swollen oogonia within filaments of narrow cells (compare these with the much broader cells observed in “A case of mistaken identity?”). These oogonia look as if they have already fused with the male antheridia to form zygotes, which will eventually be released. These zygotes can lie dormant for a long time, which makes sexual reproduction a useful technique for overcoming adverse conditions (see also: “The River Ehen in March”). Not very romantic, I know, but that’s the reality of life at the unprepossessing end of biodiversity.

Oedogonium_calcareum_Whitba

Oedogonium calcareum from Whitbarrow tufa stream, May 2015, showing oogonium. Arrows indicate position of “caps” (scar tissue from intercalary cell division) a. scale bar: 20 micrometres (= 1/50th of a millimetre); b. & c.: scale bar: 10 micrometres (= 1/100th of a millimetre).

Following in Arthur Ransome’s footsteps …

Riga_May2015

Town square in old Riga, with St Peter’s church and the ‘House of Blackheads’, once belonging to the ‘Guild of Unmarried Merchants’.

Last week, as I watched sailing dinghies on Windermere from the windows of the Freshwater Biological Association’s laboratory, I was reminded of the novels of Arthur Ransome, which I had read avidly when I was young. This week, by curious serendipity, I find myself in another city with strong associations with Arthur Ransome. In preparation for this trip, I pulled my old copy of Racundra’s First Cruise from my bookshelf and started reading. The first paragraph is one of the most evocative in all travel literature:

“Houses are but badly built boats so firmly grounded that you cannot think of moving them. They are definitely inferior things, belonging to the vegetable not the animal world, rooted and stationary, incapable of gay transition. I admit, doubtfully, as exceptions, snail-shells and caravans. The desire to build a house is the tired wish of a man content thenceforward with a single anchorage. The desire to build a boat is the desire of youth, unwilling yet to accept the idea of a final resting-place.”

That was written in 1923, as Ransome sailed in his small cruiser, Racundra, travelling from Riga to Tallinn (then known by it’s German name, Reval), and then across the Baltic to Helsinki (which Ransome refers to by it’s Swedish name, Helsingfors), and finally back to Riga. Ransome, at the time, was the Guardian correspondent in Russia, and had covered the Russian revolution and the subsequent wars of independence in the Baltic states. The person referred to coyly as ‘The Cook’ was actually his lover (he was already married at this time), Eveginia Petrovna Shelepina, formerly Trotsky’s secretary.

And so here I am in Riga, en route to a scientific meeting and, alas, amongst the ‘badly built boats’ of the terrestrial world rather than afloat. Ransome’s phrasing is harsh on Riga, whose old town centre is a UNESCO World Heritage Site, with architecture betraying its historical links with Germany, as part of the Hanseatic League. Walking through the old town’s narrow cobbled streets, lined with attractive gabled buildings was a delight, though the journey in from the airport contained plenty of reminders of Riga’s recent past as part of the Soviet empire.

I’m enjoying the food here, too: hearty meat-rich dishes washed down with local beers. The words ‘sausage’ and ‘dumpling’ crop up frequently on menus, separately and, on occasions, together. This is not a great place to be a vegetarian, I fear. My culinary highlight? Sliced bull’s testicles. Recommended, so long as you are not the one who has to explain to the bull what is about to happen.

Ellerbeck and Ellerbeckia

In the post I wrote just after John Lund’s death had been announced (see: “John Walter Guerrier Lund (1912-2015)”), I mentioned that there was a diatom genus named after his house in Ambleside. As I was in the area, I thought I would pay a quick visit so that I could put a picture of Ellerbeck, the house, alongside images of Ellerbeckia, the genus.   I walked down off Loughrigg Fell, through Ambleside and onto the road that leads out towards Kirkstone Pass. A left turn onto, Sweden Bridge Lane followed by a right onto Ellerigg Road brought me, a couple of minutes later, to Ellerbeck, the last of a row of stone cottages right at the edge of the village.

Set on a hillside and surrounded by garden plants, Ellerbeck was not an easy house to photograph, so forgive the odd perspective in the picture below.   The gardens around Ellerbeck are, I imagine, quite wonderful in the summer, though today was not a day to linger.

Ellerbeck_Ambleside

Ellerbeck: the home of John and Hilda Canter-Lund in Ambleside, Cumbria, photographed May 2015.

The next pictures show Ellerbeckia arenaria, the only representative of the genus found in the UK.   First there is a colony of live cells; after this, I have included some views of cleaned valves.   It is, as you can see, a large, heavily silicified valve with a distinctive cross-hatched pattern on the mantle.  The cells are joined together to form long chains, which often stay together even after the cells have been cleaned with oxidising agents.   One interesting feature of Ellerbeckia that is not easy to see with the photographs here is that the two valves that make up the cell wall are different from one another. One has a convex face, whilst the other has a concave face.   The radial markings on the valve face also differ, so that the “ridges” on one knit with the “grooves” on the next.   This may explain why the colonies are so resilient compared to, for example, Melosira varians (see “Fertile speculations”).

Ellerbeckia_arenaria_CFC

Ellerbeckia arenaria, photographed by Chris Carter.

There is an irony to Ellerbeckia, the genus, being named after a house surrounded by the soft waters of the Lake District in northern England. Looking at my database, I noticed that most of my records were from hard waters in the south, including several chalk streams. I have found it in Cassop Pond, near my house, which is at the foot of the Permian limestone escarpment, but I would not expect to find it in the softer waters of the Lake District.   On the other hand, my old copy of West and Fritsch (1927) says it “occurs on wet rocks, sometimes forming crisp mat-like masses on dripping sandstone, and is common on the Brit[ish] Carboniferous sandstone.”   Maybe I’m just not looking in the right places.

Ellerbeckia_arenaria_112045

Cleaned valves of Ellerbeckia arenaria, from the Great Stour (Kent), Ripper’s Cross, May 2011.

Reference

Crawford, R.M. (1988) A reconsideration of Melosira arenaria and M. teres, resulting in a proposed new genus. pp. 413-433. In: Algae and the Aquatic Environment, edited by F.E. Round. Biopress, Bristol.

West, G.S. & Fritsch, F.E. (1927). A Treatise on the British Freshwater Algae.   Cambridge University Press, Cambridge.

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.

 

Diatoms and the space-time continuum …

A month ago, I wrote about the problems I had identifying Gomphonema species in the River Ehen (see “Diatoms and Dinosaurs”).   My work on the River Ehen happens in brief, intense bursts before I have to move on to other jobs and, once in a while, I need to sit back and take some time to revisit some of my older samples in order to compare their composition with that of my most recent collections. The first picture below is a sample from March 2013, the lower comes from a location about 2.5 km downstream in April 2014.   In both cases, the larger cells correspond most closely to Gomphonema gracile whilst the smaller ones look like members of the G. parvulum complex. However, when you arrange the cells in order of diminishing size, there seems to be a continuum between the long “G. gracile” cells and the shorter “G. parvulum” cells.   This seems to confirm what Dawn Rose and Eileen Cox were saying in the paper to which I referred in my earlier post. You may remember, too, that I commented on a similar phenomenon occurring in populations of Hannaea arcus from the River Ehen (see “Diminishing with age …”).

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Gomphonema gracile / parvulum from the River Ehen, Mill, March 2013.

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Gomphonema gracile / parvulum from the River Ehen, Ox-bow, April 2014.

The phenomenon becomes more interesting when I compare the dimensions of Gomphonema cells in the two samples.   First, I measured 25 cells in two samples from exactly the same location in the River Ehen but collected 15 months apart. In December 2013, the median length was 32 µm (max: 51; min: 21 µm) whilst in April 2014 it was 25 µm (max: 38; min: 17).   This confirmed what I suspected as I had photographed the diatoms: the smaller diatoms were more abundant in the April 2014 sample compared with December 2013. Note that the largest cells encountered are of a similar size, but there is a longer “tail” of small cells, as we might expect if we were observing the natural cycle of size reduction.

Next, I compared the dimensions of two samples collected on the same date but 2.5 km apart.   This time, cells at the Mill (the upstream site) were generally larger (median: 32; max: 39; min: 23) than those at the Oxbow.   What I think may be happening here is that the upstream populations are, to some extent, “seeding” populations further downstream. Some of the cells will be washed out of the biofilms and a few of these may become lodged into biofilms further downstream where they, in turn, will establish and, in time, divide.   So far, we only have the scraps of evidence from the Ehen plus some data for a different species in the River Wear to support this hypothesis but it is worth exploring in more detail at some point.

Gomphonema_lengths_same_sit

Valve length for 25 cells of Gomphonema gracile / parvulum from River Ehen, oxbow, in December 2013 and April 2014.

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Valve length for 25 cells of Gomphonema gracile / parvulum from River Ehen, Mill and Oxbow, in April 2014.

There is another twist to this tail because the consensus in the literature is that “Gomphonema gracile” is more sensitive to pollution than “Gomphonema parvulum”. My experience is that any reference to the ecology of diatoms should be treated with caution, as it is often laced with hearsay and tradition rather than underpinned by hard evidence. However, a quick look at datasets that I have suggested that this difference in preferences might be the case, despite the morphological continuum. The 90th percentile of alkalinity measurements for samples which contained “G. gracile” was 58 mg L-1 CaCO3, whereas for samples containing “G. parvulum” it was 175 mg L-1 CaCO3. An outlier of G. gracile was recorded at 224 mg L-1 CaCO3 but this record represented a single valve (i.e. half a dead diatom). I have put both species names in inverted commas because of the taxonomic and nomenclatural confusion that makes all of our records somewhat suspect. A similar situation occurs with phosphorus, with “G. gracile” being associated with sites with lower phosphorus concentrations than “G. parvulum”.   The 90th percentile of reactive P measurements for samples with “G. gracile” was 28 µg L-1, whereas for “G. parvlum” it was 173 µg L-1.

I think that there are two possible explanations for these patterns. The first is that the species that is more likely to occur downstream will be associated with higher alkalinity and nutrients, because this reflects the general longitudinal change along rivers. However, another possibility is that environmental preferences change during the cell cycle. There is extensive evidence from ecotoxicology which demonstrates that young life stages of many species are much more sensitive to a whole range of stressors than mature stages. There is, to the best of my knowledge, no similar evidence for diatoms, but it is conceivable that the initial cells, for example, may be more sensitive than cells later in the life cycle.   This, then, could also work to restrict the distribution of “G. gracile” to cleaner stretches of river, and prevent reproduction in the enriched conditions that “Gomphonema parvulum” can tolerate.

Far more questions than answers.  As I alluded in Diatoms and Dinosaurs, there is an unwritten assumption amongst many diatom taxonomists that the silica frustule contains all that we need to know in order to understand diatom taxonomy.   A number of taxonomists are challenging this assumption with their work now, but there are still many traditionally-minded taxonomists out there whose horizons do not extend beyond the frustule. Yet there are also several diatom genera, not just Gomphonema, where silica-based taxonomy seems to generate more heat than light. I do wonder how many more of these problems might resolve themselves if people took the time to stand back and consider the life cycle in a more rigorous manner.

 

 

The mysteries of Clapham Junction …

One of the surprises of our short visit to Malta was encountering signs directing us to “Clapham Junction”, which turned out to be the informal name for an area known in Maltese as Misraħ Għar il-Kbir.   The term arises from the deep “cart tracks” gouged into the limestone pavements which criss-cross in the manner of railway lines outside a busy station. Similar ruts are found at several locations in Malta and pose one of the island’s great archaeological mysteries. The best guess is that they originated at around 2000 BC, possibly as a result of primitive carts or sleds being pulled across the naturally weak limestone.

Clapham_Junction_Malta

Clapham Junction, Malta. The right hand picture shows the deeply-rutted limestone pavement that gives the area it’s name.

On the day we visited, the site was almost deserted. The downside of this was that we stumbled through the scrubby vegetation for some time before we actually found the tracks for ourselves (eventually sighting another couple of tourists on a nearby ridge).   But there is something quite special about straying away from the tourist honeypots, away from interpretation boards and signage, and exploring these locations alone.

Ghar_Il-Kbir

The cave complex at Għar il-Kbir, April 2015.

A little further away, behind a dry stone wall, the land fell away into a natural hollow, which was, until the roof collapsed a natural “karst cavern”.   Caves around the edge of this hollow show signs of habitation: walls at the entrance and dividing the living space within the caves.   Life as a troglodyte makes perfect sense in the harsh Mediterranean climate of Malta and there is evidence that these caves were inhabited until the early 19th century.

Inside, my eyes were caught by the blue-greenish films on many of the rocks.   Algae, like humans, do not thrive in the hot, dry climate here so, again like humans, they seek out cooler, more shaded situations.   I scratched a few flakes of the film off the stones to take home so that I could have a closer look.   When I got back, I put them on a slide with a drop of water and put this under my microscope for a closer look. What I saw was a mass of tiny cells.  My best guess at a name for these colonies is Gloeocapsa alpina (the species name was suggested by Allan Pentecost) .  We have met this genus at least once before, co-incidentally also associated with an archaeological site (see “More reflections from the dawn of time”). If you look closely at the final picture, taken by Chris Carter, you’ll see the typical prokaryotic cell lacking distinct chloroplasts.

Aphanocapsa_Ghar_Il-Kbir

Inside the largest cave at Għar il-Kbir with (right) the blue-green crust under the microscope (scale bar: 10 micrometres (= 1/100th of a millimetre).

The higher humidity in the caves makes it slightly easier for the algae to survive than outside and there is also evidence that cave-dwelling species have specially-adapted photosynthetic apparatus to allow them to make the most of the limited light that is available here. Understanding the growth off microorganisms in environments like this also needs a major re-adjustment in thinking. Outside the caves we had been wandering through masses of wild flowers that thrive in the spring in the makkja (the Maltese term for the Mediterranean scrub vegetation). When we pass through the entrance to the cave, however, we have to slow our mental time clocks down, and stop thinking in terms of annual, biennial or perennial plants.   These algae, along with those that thrive as crusts in deserts, hot and cold, are opportunistic, capable of “shutting down” their metabolism for long periods (years, if  necessary) then “rebooting” to make the most of brief periods when there is enough water to function.

Aphanocapsa_CFCarter

The cyanobacterium Gloeocapsa alpina from Għar il-Kbir, Malta, April 2015.   Photograph by Chris Carter.

So much for the algae. The sun was now high in the sky and if you really want to understand the ecological realities of the Mediterranean climate, I recommend a three kilometre walk to the nearest village in search of shade, a drink and some lunch.

Reference

Albertano, P. (2012). Cyanobacterial biofilms in monuments and caves. pp. 317-344 In: The Ecology of Cyanobacteria II: Their Diversity in Space and Time (edited by B.A. Whitton). Springer, Dordrecht.

Vestal, J.R. (1993). Cryptoendolithic communities from hot and cold deserts: speculation on microbial colonization and succession. Pp. 5-16. In: Primary Succession on Land (edited by J. Miles & D.W.H. Walton).   Blackwell Scientific Publications, Oxford.

Is our world too complex to be trusted to politicians?

I am not the only person to comment that the environment has been largely sidelined in the 2015 General Election (see “A plague on both their houses“).   As a result, my efforts to find points of contact between the election campaigns and my life as an ecologist have taken some odd twists and turns.   What, for example, should an ecologist make of Ed Miliband’s attack on David Cameron’s handling of the situation in Libya in 2011, and on the Tories’ angry response?

But first, some good news: less focus on climate change in the election has, at least, spared us from the ranting of climate change deniers.   I have often found myself wondering why the opinions of few non-scientists have gained so much traction over the past decade or so. The answer, I suspect lies in the very nature of climate science, and the complexity of the systems with which it is concerned.   Note my use of the word ‘complexity’ rather than ‘complicated’. This is an important distinction. A car engine is complicated because there are many interconnected components. Nonetheless a good mechanic will understand how they all fit together and, more importantly, be able to diagnose faults and have confidence that any adjustments that s/he makes will solve the problem. Scientists understand ‘complexity’ rather differently and, crucially, recognise that cause-effect relationships are less straightforward.   This means that complex systems are less deterministic. Tinkering with one component will not necessarily have the effect you want and, indeed, may even make it worse.   Consequently, predictions need to encompass a range of outcomes, each with an estimate of its likelihood.

Climate scientists understand this and gone to great lengths to understand the uncertainties associated with their predictions and to publish these in the peer-reviewed literature. Unfortunately, this has, in the process, provided fuel to those who, for their own reasons, want to play down the implications of global warming. They can tug and tug at every thread left hanging out of the fabric of an argument and gleefully draw everyone’s attention away from the substance of the debate.   It is exactly the same tactic as that used by Creationists looking to undermine evolution.

No politician would be as naïve as climate scientists. All their policies are packaged and presented as neat, deterministic cause-effect relationships.   This is the case even when we know that, in reality, we are dealing with aspects of society, economics, international relations, or whatever, all of which are complex systems and, therefore, resilient to meddling by politicians elected with a five-year mandate.  We all want to believe the promises that politicians will Get Things Done; the issue is which set of policies we want, not whether they are being hopelessly naïve in offering them to us in the first place.

Ah yes … international relations.   This brings me back, neatly, to Libya.   The Conservatives, in their manifesto, claim credit for “….intervening to prevent a massacre in Libya”. This is true; however, they were dealing with a complex system, and short-term measures to prevent a massacre did not prevent the country’s political system subsequently unravelling, creating a space for militias and, indirectly, contributing to boatloads of migrants fleeing across the Mediterranean Sea.   Miliband clearly hit a sensitive nerve, because the Tory response was to attack him rather than to defend their policy.   To be fair, Cameron was dealing not just with a complex international issue but also with a British public jaded by lengthy, costly and ineffective interventions elsewhere in the Muslim world. And, as every Tory leader loves to be compared with Winston Churchill, we should remind David Cameron that he is in good company in his blunders in Middle East policy.

Though the details differ, climate science and international relations both belong to the same class of “complex problems”.   The difference is that practitioners of the former are frank about the issues that this raises, whilst politicians prove to be reluctant, time and time again, to publicly contemplate alternative outcomes to their policy pronouncements. And it is not just foreign policy where politicians and policy makers are reluctant to be frank about their practices and to put all their evidence in front of the public (see “The madness that is ‘British Values’” for another example).

All the political parties are guilty of this. It is the nature of the game that they play, the need to be seen to Get Things Done (or to show that the other lot failed to Get Things Done) before the cycle grinds round and we are all looking towards the next election. I am trying not to sound too cynical about the system but my professional life brings me into contact with many issues that require more time than a five year political cycle.   Perhaps – dare I write this – democracy has some limitations in our modern age?