Distant relatives …

Calder_StakesBr_June20

The easing of lockdown means that fieldwork can resume (real fieldwork, that is, rather than virtual perambulations around the margins of Lough Down) and I was in the Lake District last week collecting samples for an ongoing project.  The New Normal means a rethink of logistics to account for social distancing which, in my case, meant Heather taking the place of Ben as BenthoTorch wielder so that we could safely share a single car.

Our travels took us to the River Calder, a short river that rises on the western fells of the Lake District, just south of Ennerdale Water, and flows about 12 kilometres to join the Irish Sea at Sellafield (it actually flows through the BNFL site and those with a long memory may remember that the first incarnation of the nuclear reprocessing site was known as “Calder Hall”).   This is one of a number of rivers of this name in the UK, with an ancient Celtic root referring either to the violence of the flow or the stony nature of the bed.   The two roots are linked: a harsh hydrology will flush away all but the largest and roughest stones and, as the photograph above shows, the bed of the Calder has plenty of these.

When not photographing me peering at stream beds through a bathyscope, Heather noticed some bright yellow growths on the floor of the forest surrounding the stream which she recognised as a slime mold with the rather unappetisiing name of dog’s vomit.  For once, the Latin name, Fuligo septica, sounds more appealing.   Under the microscope, all I saw were spherical spores but these will germinate and the cells will aggregate to form an amoeboid-like mass that moves around searching for nutrients.    YouTube has some fascinating videos that shows this happening.

Fuligo_septica_June20

Fuligo septica – dog’s vomit slime mold – photographed in woodland beside the River Calder, Cumbria, June 2020 (photograph: Heather Kelly)

Slime molds interest me for another reason today: they are a group that has bounced around the tree of life in the years since I started my career.  When I was at school, slime molds were dealt with cursorily as one group within the fungi which, in those far-off days, were considered to be part of the plant kingdom.  In the far past, algae and fungi were grouped together as the “Thallophyta”.   This particular slime mold still sits in a class called the Myxomycota (literally “slime fungi”) which alludes to this heritage.  Now, the idea of fungi being relatives of the plants is quite laughable: they differ in so many ways, not least the completely different form of the cell wall and the absence of photosynthesis.   The fungi are treated as a separate kingdom but the slime molds have undergone one further divorce. No longer are they considered to be a group within the fungi, rather they have all been shifted to the Protozoa, itself also a separate kingdom.  The slime molds do, superficially, resemble some fungi in some respects but, in others, they are completely different.  This fragmentation from the straightforward view of biological classification of the past, resembles that which has occurred in the algae: once considered primitive “plants” but now spread between four kingdoms.   The Euglenophyceae, which have appeared in this blog on a couple of occasions (see “A visit to Loughrigg Fell” and “Puzzling puddles on the Pennine Way”), are, in fact, more closely related to dog’s vomit slime mold than they are to any other group of algae.

Fuligo_septica_micrograph

Microscopic view of cells of Fuligo septica, dog’s vomit slime mold. Scale bar: 10 micrometres (= 100th of a millimetre).

The slime molds are not the only group that used to be classified as fungi but which are now more closely allied to algae.   Potato blight (Phytophora infestans) belongs to the Oomycota (or “egg-fungi”, due to their large oogonia).   This group is now classified in the same kingdom (Chromista) and phylum (Heterokontophyta) as several groups of algae including the diatoms and brown seaweeds.   It is a fairly distant relationship in the grand scheme of things (equivalent to comparing yourself to a sea squirt) but it still means that I make my living from relatives of the organism that drove my ancestors to leave Ireland.

 

Some other highlights from this week:

Wrote this whilst listening to: old Glastonbury sets on the BBC iPlayer, particularly from 2009 and 2010, when I was there.   Notably Blur’s headline set (watch out for the crowd surfer who disappears from view halfway through Song 2.  I was directly underneath.   Also Dizzee Rascal from 2010 and highlights from Bruce Springsteen’s 2009 set.   And Radiohead from 1997.

Cultural highlights:  The new interpretations of Alan Bennett’s Talking Heads, produced by Nicholas Hytner on BBC2.  ]

Currently reading:   Lethal White by Robert Galbraith (aka J.K. Rowling).

Culinary highlight:  French onion ramen, a French/Japanese fusion from Tim Anderson’s Vegan Japaneasy.

The search for the perfect river …

Irt_Lund_Bridge_June20

One of the ironies of studying the health of aquatic ecosystems is that, whilst it is easy to recognise a polluted river, it is much harder to define the opposite: a river in its pristine state.  Back in the 1970s you could argue that it was not a particularly pressing question: there was so much obvious pollution in our rivers, lowland ones in particular, that simply reducing that load was the immediate concern.

The Water Framework Directive (WFD) ushered in a paradigm shift: defining the health of a river not in terms of the presence of undesirable traits (such as pollutants) but by the presence of desirable ones.  Just as a healthy human is defined by more than the absence of illness, so a healthy ecosystem means more than just an absence of pollution.   However, moving from these vague assertions to workable measures of river “health” has proved to be a substantial challenge.  The presumption was that we can define the health of a river by comparing its ecological properties with those of rivers that we already know are healthy, just as a doctor has a pre-determined idea of what a healthy body should look like and how it should behave.  Or, to put it another way, whether dealing with the human body or a river ecosystem, we compare what we can see with what we would expect to see were that body or ecosystem in peak condition.   Yet, for ecologists that begged another question: these expectations should be based on our own experience yet are there enough rivers left on our small, crowded , busy island in this perfect state to provide us with the experience we need in order to judge the condition of every other river?

Our search for these “perfect rivers” took us to the remotest corners, where the human footprint is barely discernible.  Information we got from these rivers allowed us to form a view of the properties to which all rivers and lakes should aspire.  There was, however, a hitch: these remote, unpopulated regions are generally unpopulated for a reason: their geological foundations made them unsuitable for most forms of agriculture, for example, so using these as a basis for comparisons with rivers in regions where the geological foundations gave rise to flatter landscapes and richer soils was not ideal.

We’ve grappled with this problem over the years and, like Goldilocks, failed to achieve complete satisfaction on our first two attempts.   Our original effort was deemed, after testing, to be too stringent by Environment Agency.  Chalk streams, in particular, even when they supported rich invertebrate and plant communities failed to achieve the crucial “good status” criterion when their diatoms were assessed.  The second effort, however, swung too far the other way, which made it unusable in hard water areas.   We’ve been scratching our heads for a few years to find a way of defining the “expected” condition for the large number of rivers that flow across lowland areas of the UK, but for which there are no pristine examples against which their ecological properties can be compared.

Our third attempt (“just right”, to push the Goldilocks analogy) has just been published in Ecological Indicators.   What we have done differently this time is, rather than seek out perfect examples of lowland rivers, we have looked at a large dataset of TDI values calculated from diatom samples – irrespective of the level of pollution – and plotted that against alkalinity (which shows the influence of limestone in the catchment).   The bottom edge of this relationship, then, shows the best we can expect at any particular alkalinity.   There are bells and whistles that don’t really belong in a blog post, but that’s the essence of the new approach.

Kelly_et_al_2020_Fig2

Modelled reference TDI values overlain on scatter plot of observed TDI. Blue line = original reference equation (“too stringent”: spring dashed, autumn solid); black line = current reference equation (“too lenient”); red line = new reference equation (“just right”: spring dashed, autumn solid).   Figure 2 from Kelly et al. (2020).

This immediately raises a question: how do we know that the best we’ve got is the best we can attain?  Suppose that all of our rivers are sufficiently altered by human actions that even the best we’ve got isn’t good enough?   There isn’t an easy way to answer this and, in fact, this approach was frowned upon for a long time because of the ambiguity in the outcomes.  However, having failed with all other approaches, and with so much more data available now, we felt that it was worth revisiting this approach.  Even so, the final step still needs to involve a scrutiny of the values produced in order to make a judgement about whether the best we’ve got equates to the elusive “reference state”.  The alternative is to use this value to define a different boundary (when I was involved in a similar exercise for Romanian lakes, for example, we decided that the best we had equated to the boundary between high and good status, rather than to the reference state).

The pure scientist may shudder at the thought that the final call is subjective rather than objective but a philosopher might understand us better. We have shifted our perspective from realism to idealism: the perfect stream, in other words, exists in our imaginations not in a real landscape (just as economists know that “perfect competition” is unattainable).   The early years of WFD implementation were dominated by this search for ideal “reference sites” but, apart from a few remote areas where population densities were low and wilderness still existed, the reality often proved elusive.  Over time, attention shifted to making sure that everyone agreed on a notion of “good enough” (the boundary between “good ecological status” and “moderate ecological status”).  Pragmatism won out over idealism and, more importantly, everyone recognised the dangers of basing a nation’s water management policy on extrapolation from the few plausible “reference sites”.    However, we’ve tried to keep alive the idea of a “guiding image”: a competent ecologist should be able to visualise the ecological condition to which s/he hopes that any individual stream or river could attain.    Nigel Willby wrote a thought-provoking editorial for Aquatic Conversation on this topic back in 2011 and this exercise of imagination, which seems at odds with the quantitative thrust of most modern ecology, is a valuable reality-check for the outcomes of high -powered statistical models.   Models are good friends, when it comes to addressing questions such as this, but poor masters.  At some point, some old-school boot-on-the-ground common sense is needed to spark their dry quantitative outputs into life.

Reference

Kelly, M.G., Phillips, G., Juggins, S. & Willby, N.J. (2020).  Re-evaluating expectations for river phytobenthos assessment and understanding the relationship with macrophytes.  Ecological Indicators 117: 106582

Willby, N.J. (2011).  From metrics to Monet: the need for an ecologically-meaningful guiding image.  Aquatic Conservation: Marine and Freshwater Ecosystems 21: 601-603.

Low_Butterby_June20_#2

Low Butterby pond, an ox-bow lake on the flood plain of the River Wear with flag iris and yellow water lily.  The photograph at the top of the post shows Lund Bridge over the River Irt in Cumbria. 

Some other highlights from this week:

Wrote this whilst listening to: I’ve taken a brief break from my Bob Dylan retrospective.  Enjoyed Phoebe Bridgers new album, Punisher, which led me back to Julien Baker’s album Turn out the Lights, as well as their joint EP as Boygenius.

Cultural highlights:  Days of the Bagnold Summer: lo-fi British comedy about a heavy-metal obsessed adolescent and his relationship with his mother.

Currently reading:   Peter Hessler’s Country Driving: A Chinese Road Trip.   Fascinating travel book that gets under the skin of modern China.

Culinary highlight:  a Victoria sponge with “peanut butter and jelly”-flavoured icing.  The search for a decent dairy-free icing/frosting continues with this is a strong contender.

More about Spirulina …

Spirulina_milled

This post is a brief follow-up to my post “Twisted tales …” in which I wrote about the cyanobacterial genus Spirulina.   My interest piqued, I bought a packet of milled Spirulina from a local health food shop and added it to pasta dough to make a rather vivid green tagliatelle.   The photograph below shows the result of adding about a tablespoon of Spirulina powder to a dough made from 150 g of flour and two eggs.

The effect, I should add, was mostly to add colour rather than flavour.   However, it made a fine bed to a portion of salmon cooked in a brandy source to an Asturian recipe in Claudia Roden’s The Food of Spain.   I remain a sceptic about the claims for Spirulina as a “superfood” (is there any such thing?) but it is high in protein (67%) and low in fat (0.9%) so it is certainly healthier than many of the ingredients that pass through our kitchen.   I’m also expecting that it will add a umani “kick” to sauces, stews and soups, though we haven’t got around to trying this yet.

Spirulina_tagliatelle

Spirulina powder and (right) home-made pasta dough with added Spirulina.  The photograph at the top of the post shows the fragments of Spirulina filaments in the powder (each about 10 micrometres – 100th of a millimetre – wide).

Some other highlights from this week:

Wrote this whilst listening to: Down in the Groove, Dylan and the Dead (a live album recorded in 1989 with the Grateful Dead) and Modern Times.  The latter is definitely a return to form after a few flat studio albums in the mid-1980s.

Cultural highlights:  Not sure that I can think of one this week.

Currently reading:   J.K. Rowling’s Harry Potter and the Chamber of Secrets: more nostalgia for the days when the children were young enough to want books read to them.

Culinary highlight:   Probably the salmon in a brandy sauce mentioned above served on home-made tagliatelle.

sprirulina_tagliatelle_with_salmon

The strange case of the migrant diatom …

Ach_tepidaricola_Elia_near_Vyzakia_190313

I’m taking time during lockdown to catch up on some papers that I had been meaning to write for some time.  One of these, for a special issue of the journal Ecological Indicators, is about the diatoms of Cyprus, a subject that I’ve touched upon in a few earlier posts (see “Diatoms from the Troodos Mountains”).  Writing about Cyprus, even via the dry prose of an academic paper, reminded me how much I had enjoyed earlier visits, and when I might be  able to return.

Most of the hard work to produce the data in this paper was, I have to admit, done by Marco Cantonati and, in the process, he has found several species that had not previously been described, which makes us wonder if the endemism for which the higher plant flora of Cyprus is well-known also extends to the diatoms.  There has been a vigorous debate about the extent to which diatoms are cosmopolitan rather than restricted to particular geographic areas in recent years, with evidence now to show that some species definitely seem to be cosmopolitan whereas others are much more localised in their distribution.  The diatom flora of an island such as Cyprus ought to be a valuable test case for this.

One species that we had not seen before but which, after searching the literature, Marco was able to match with a previously-described species was Achnanthidium tepidaricola – shown in the picture at the top of the post.  Achnanthidium is a large genus of small diatoms, and we have only really started to appreciate the diversity within the genus over the past 20 years or so (see “Quantifying our ignorance …”).  This particular species, however, has a story to tell.  It was first found growing on a wet stone wall in a greenhouse in the National Botanic Garden in Meise, Belgium by Bart van der Vijver a few months after the wall had been constructed.   Finding the same species in Belgium and Cyprus ought to be a hint that it is relatively cosmopolitan.  However, our story has an interesting twist …

The twist is that the wall that Bart sampled in the greenhouse in Meise was built with stones that had been imported from Turkey.  Suddenly, A. tepidaricola is looking less Flemish and more like a migrant.   Turkey is, of course, the nearest mainland country to Cyprus, and shares the same arid climate of the eastern Mediterranean.   Many of the streams in this part of the world will, naturally, dry out in the summer and the diatoms will have to be prepared to survive in these conditions.   Suddenly, A. tepidaricola growing both in Cyprus and on that one particular wall in Belgium is looking less like evidence of endemism and more like a hint that, even if not endemic to Cyprus, this species may be characteristic of the eastern Mediterranean.  It may be more widespread than that, but this is certainly where it is being recorded at the moment.

That’s the trouble with biogeography: the distribution of species is forever shifting, and our modern joined-up world only accelerates this process.  Dump a pile of stones from Turkey almost anywhere else in Meise and the Flemish climate would probably have sent Achnanthidium tepidarociola to the Great Biofilm in the Sky.  But these particular stones were put into a greenhouse where they were able to thrive and, eventually, to be noticed by Bart.   Humans helping previously unknown bugs to move across the world?  Where else have I heard about that before?

The photo at the top of this post was taken by Marco Cantonati and shows a population of Achnanthidium tepidarocola from Vyzakia, Cypris in March 2019.

Reference

Van der Vijver, B., Jarlman, A., Lange-Bertalot, H., Mertens, A., de Haan, M. & Ector, L. (2011).  Four new European Achnanthidium species (Bacillariophyceae).  Algological Studies 136/137: 193-210.

 

Some other highlights from this week:

Wrote this whilst listening to: 1980s Bob Dylan (probably not his greatest period): Empire Burlesque and Knocked Out Loaded.  Also an elderly, rather scratchy recording of Rachmaniov’s first two piano concertos with Rachmaniov himself on piano.   And Scottish singer-songwriter Siobhan Wilson’s There Are No Saints.  Well worth checking out, if you have never heard her before.

Cultural highlights:  Jojo Rabbit.   This one split the critics but was a box office hit.  There were too many negative reviews when it first came out for us to make the trip out to see it but our son persuaded us to give it a try.  Glad we did.   Very clever soundtrack.

Currently reading:   HG Well’s War of the Worlds.

Culinary highlight:   Caesar Salad, from a Felicity Cloake recipe in The Guardian.  We also found some pumpkin lurking in the depths of the freezer and turned it into a pie.   Ate both whilst sitting in the garden: a rare treat in our climate.

A load of balls …

Lough_Cullin_BKennedy

This post is still mostly about the ecology of Lough Down, though it draws heavily upon photographs taken at Lough Cullin, in County Mayo, Ireland.   Lough Down shares some characteristics with Lough Cullin, but more with Lake Wobegon.   I suspect that the summers in Lough Down are not quite as long or as hot as those experienced around Lake Wobegon but, also, that a walker passing around the edge of Lake Wobegon would not see the round balls of algae that are a common sight along the shoreline of Lough Down.   Maybe I’m wrong: if anyone in Minnesota knows differently, please do let me know.

From a distance, these look like an unsightly mass of algae cast up on the foreshore; it is only when you get close that you see that this mass is, in fact, composed of a large number of discrete spherical growths.   You can see, in the photograph below, where Bryan Kennedy, my erstwhile Lough Down correspondent, has built a few of these into an Andy Goldsworthy-esque sculpture.   These are “Cladophora balls”, a phenomenon encountered in lakes around the northern hemisphere.  In Japan, they’ve even made their way onto postage stamps.

Aegagropila_Lough_Cullin

Aegagropila linnaei washed up on the shore of Lough Cullin, Co. Mayo, Ireland.  The photograph at the top of the post also shows Lough Cullin (photographs: Bryan Kennedy).

Until relatively recently, as their name suggests, the alga from which these balls are formed, belonged to the genus Cladophora, a frequent subject on this blog (see “The pros and cons of cell walls” for a recent example).   Like Cladophora, these are branched filaments composed of relatively large, multinucleate cells with a reticulate chloroplast.  This was, however, recognised as a different species to Cladophora glomerata, the common species of enriched lowland rivers: Cladophora aegagropila.  However, recent molecular studies have shown that it is not so closely related to Cladophora glomerata as its outward appearance suggests, leading to the resurrection of a very old name, Aegagropila linnaei.

In rivers, Aegagropila linnaei forms carpet-like growths of short filaments, not growing into the long wefts that we associate with Cladophora glomerata.  However, C. glomerata can sometimes be profusely branched as well, so telling these two species apart both in the field and under the microscope can be tricky.   One of the most useful characteristics is that the branches of Aegagropila are sub-terminal, meaning that they arise just below the end of the parent cell, rather than at the end, as is the case in Cladophora (see diagram below).   It is strange that two such similar species in appearance are, in fact, not particularly closely-related.  This is, however, an important distinction asA. linnaei prefers, as far as we can tell, less enriched conditions than C. glomerata.

Aegagropila

Left: a section through a ‘Cladophora’ ball from Lough Cullin and, right, profusely-branched filaments of Aegagropila linnaei.  Photographs: Bryan Kennedy.

Why does it form these distinctive spherical growths in lakes?   I have not managed to find a paper that gives an authoritative explanation so here are a few possibilities, none mutually exclusive.  First, filamentous algae that display apical growth and copious branching tend to form hemispherical growths if attached and spherical ones if not.  We’ve seen that for Cyanobacteria such as Rivularia (see “More about Rivularia”) and Gloeotrichia (see “Rewriting history at Talkin Tarn”).  Second, the constant ebb and flow in the lake littoral zone will create a physical stress on attached carpets of Aegagropila leading, eventually, to parts becoming detached.  Third, the profuse branching that is characteristic of Aegagropila will mean that adjacent filaments will become entangled around another, creating a Velcro-type effect.   Finally, the apices of the filaments will continue to grow towards the light, meaning that the free-floating balls gradually expand in size.

Aegagropila’s dislike of nutrient-rich conditions mean that the number of places where it is found has been decreasing over recent decades.   It was, for example, recorded from several locations in the Netherlands in the past but not since 1967.  There are records from in the UK, but mostly from the more remote regions.   There are also a number of records from loughs in Ireland, as is the case here  The river form is, in my opinion, hard to differentiate unequivocally from Cladophora glomerata without very careful examination and this raises the spectre of “identification by association”, particularly when it is recorded by macrophyte surveyors who often do not have time to check material under the microscope.   Christian Boedeker, who has done much of the recent work on Aegagropila, thinks that a limited dispersal capability will mean that it will be slow to re-colonise habitats once it has been lost.

So that’s another day over here at Lough Down, a quiet lake that no-one has visited but everyone has got to know very well.   It’s one of those places, I like to think, where naturalists notice all of nature, not just the pretty, cuddly and exciting things.  Everyone leaves a little wiser, even if only because they have noticed that something everyone else overlooks is, actually, a thing of great intrinsic beauty.  As Garrison Keillor himself once said: “Thank you, God, for this good life and forgive us if we do not love it enough”.

Aegagropila_v_Cladophora

Diagrams of branching patterns in Aegagropila linnaei (a.) and Cladophora glomerata (b.).   Note how the branches of A. linnaei arise just below the end of the cell (“sub-terminal”, indicated by arrows) whereas the branches of C. glomerata arise at the ends.

References

Boedeker, C., & Immers, A. (2009). No more lake balls (Aegagropila linnaei Kützing, Cladophorophyceae, Chlorophyta) in The Netherlands? Aquatic Ecology. https://doi.org/10.1007/s10452-009-9231-1

Boedeker, C., Eggert, A., Immers, A., & Wakana, I. (2010). Biogeography of Aegagropila linnaei (Cladophorophyceae, Chlorophyta): A widespread freshwater alga with low effective dispersal potential shows a glacial imprint in its distribution. Journal of Biogeography. https://doi.org/10.1111/j.1365-2699.2010.02309.x

Boedeker, C., Kelly, C. J., Star, W., & Leliaert, F. (2012). Molecular phylogeny and taxonomy of the Aegagropila clade (Cladophorales, Ulvophyceae), including the description of Aegagropilopsis gen. nov. and Pseudocladophora gen. nov. Journal of Phycology. https://doi.org/10.1111/j.1529-8817.2012.01145.x

 

Some other highlights from this week:

Wrote this whilst listening to: This post has been a long time in gestation, so ’ve listened to a lot.  These included Bob Dylan’s Shot of Love, Infidels and Real Live, as well as Courtney Barnett’s A Sea of Split Peas and Arvo Pärt’s Tabula Rasa.

Cultural highlights:  The National Theatre At Home’s Streetcar Named Desire, starring Gillian Anderson.

Currently reading:   JK Rowling’s Harry Potter and the Philosopher’s Stone.  Comfort reading.

Culinary highlight:   I have to admit that fish, chips and mushy peas from Bells in Gilesgate was hard to beat.

Twisted tales …

Spirulina_ChrisCarter-

As opportunities for field work are still limited, I have returned to the banks of Lough Down for this post.   Lough Down, as some of you will have worked out for yourselves, is not somewhere that can be defined in terms of exact geographic co-ordinates, rather it is a state of mind.  However, that means that, in ecological terms, it is as diverse as I want it to be and, as such, it offers plenty of opportunities for writing about algae that I would not otherwise come across.   Thankfully, Chris Carter is another habitué of Lough Down and its environs, so I can use his pictures to illustrate these posts.

I used a Pasteur pipette to suck up a likely-looking patch of algae growing over some fine sediments in the littoral zone of Lough Down and brought this back to examine under my microscope.  When magnified, I was presented with the view of blue-green coloured helices twisting and turning across my field of view which means that this is almost instantly identifiable as the Cyanobacterium genus Spirulina.   It is, in effect, a helical cousin of genera such as Phormidium and Oscillatoria which we have encountered many times in this blog.   If you look closely, you’ll see that there are no heterocysts – the specialised cells responsible for nitrogen-fixation – whilst this particular population also has no gas vacuoles.  These are structures inside the cell which make the cells buoyant.  Many of the Spirulinaspecies found in warmer parts of the world have these, enabling them to live suspended in the water, whereas the temperate species tend to live at the bottom of lakes and ponds.  Whilst a few species definitely prefer freshwaters, most are associated with brackish and marine habitats, including saline lakes in Africa such as Lake Chad.

Spirulina is not a particularly common alga in UK and Irish freshwaters, but there is one habitat where it can be conspicuous: the shelves of health food stores.   All sorts of claims have been made for its health-giving properties – some supported by evidence, others not – earning it the epithet “superfood”.   There is, for example, evidence that women from communities around Lake Chad who regularly ate Spirulina (“Dihé”) had higher levels of Vitamin A than those who did not.   However, vitamin A deficiency is common in the region and the effects would not be pronounced in regions where there was a greater range of sources of vitamin A in the everyday diet.   On the other hand, Spirulina comes from the same sub-class as a number of Cyanobacteria known to produce neurotoxins, and there is some evidence (admittedly much less than for other genera) for it also producing toxins.   The aggressive marketing of Spirulina is enough to make me wary: there is no such thing as a “superfood”, except as one small part of a balanced diet.   Buy it and use it, by all means, but do not expect miracles.

I should mention, in closing that “Spirulina”, as commonly understood, is actually two genera: Spirulina and Arthrospira.  Much of the material sold as health food actually belonging to the genus Arthospira, which is broader than Spirulina and has more distinct cross-walls.   Looking at the Freshwater Algal Flora of the British Isles, I see a record for Arthrospira jenneri from a pond just a short cycle ride from my house from 1938.  Maybe I should make a trip one day soon to see if it is still there …

References

McCarron, P., Logan, A. C., Giddings, S. D., & Quilliam, M. A. (2014). Analysis of β-N-methylamino-L-alanine (BMAA) in Spirulina-containing supplements by liquid chromatography-tandem mass spectrometry. Aquatic Biosystems. https://doi.org/10.1186/2046-9063-10-5

Roy-Lachapelle, A., Solliec, M., Bouchard, M. F., & Sauvé, S. (2017). Detection of cyanotoxins in algae dietary supplements. Toxins. https://doi.org/10.3390/toxins9030076

Soudy, I. D., Minet-Quinard, R., Mahamat, A. D., Ngoua, H., Izzedine, A. A., Tidjani, A., … Sapin, V. (2018). Vitamin A status in healthy women eating traditionally prepared Spirulina (Dihé) in the Chad Lake area. PLoS ONE. https://doi.org/10.1371/journal.pone.0191887

Wrote this whilst listening to: Bob Dylan’s Live at Budokan, Slow Train Coming and Saved.  Also, Big Thief’s new single Love in Mine.  Still not sure how I missed their set at Green Man 2019.

Cultural highlights:  Enjoyed the film Peanut Butter Falcon, an indie hit last year which we missed first time around.   Also discovered a podcast on Spotify called Winds of Change by American journalist Patrick Radden Keefe.  It might be about American soft power and psy-ops at the end of the Cold War or it might just be a loopy conspiracy theory.  Not sure I know myself yet.

Currently reading:   Just about to start Sarah Walter’s The Paying Guest.

Culinary highlight:   Either a Yotam Ottolenghi recipe for tamarind and tomato braised chickpeas from the Guardian [https://www.theguardian.com/food/2020/may/09/tamarind-tomato-braised-chickpeas-savoury-porridge-browned-butter-lime-rice-pudding-yotam-ottolenghi-thrifty-recipes] or an improvised East-meets-West better-than-it-sounds risotto topped with steamed sea bass with ginger and spring onions.

How not to win the Hilda Canter-Lund competition

HCL_winners_2009&2010

The 2020 Hilda Canter-Lund competition for the best photograph of an alga is underway again, with a closing date of Friday 5 June.  Over the years I’ve written a few posts to encourage entries, by focussing on what makes a good entry for the competition (listed at the end of this post).  This time, however, I’m coming at the problem from a different angle because, each year, as we make our first review of entries in order to prepare a shortlist, the judges always reluctantly leave one or two images out due to fairly basic flaws that could have been corrected prior to submission.   At least two of our winners have used smartphones for their photos and even these now have basic editing capabilities, so there really is no excuse for a little cropping or tonal adjustment prior to submission, if that is what it takes.

A photograph is a record of a unique event.   It is objective, up to a point, but it reflects a decision, made by the photographer, about when to release the shutter.   The microscopist scans a slide, and picks out particularly well-presented organisms or cells, not overlain by other cells or detritus in the sample, and also for pleasing juxtapositions of cells or filaments.   The same applies to those who photograph larger algae.  Tiff Stephens, the 2016 winner, could have waited a few moments longer, taken a step along the deck to her left or right, or held the camera at a slightly different angle.   Each would have given her a slightly different image of essentially the same phenomenon.  Whether photographing landscapes or using a microscope, there is nothing sacrosanct about the image beyond it being a record of the photographer’s decision to press a button.  Indeed, I suspect that most of our shortlisted entries are not unique records of the phenomena they record, but one of a number of images, and that a second stage of decision-making is needed to select the image that will be used.

Tiff_Stephens_Swell_Life

Tiffany Stephen’s Swell Life: winner of the 2016 Hilda Canter-Lund prize.   The images at the top of the post show the 2009 and 2010 winners of the Hilda Canter-Lund competition, by Mariano Sirioni and Ernesto Macayo respectively. 

Having challenged the idea that the image, itself, is sacrosanct, there is no particular reason why you should not apply a third stage of decision-making and edit the image to enhance the story that you want to tell.   The field of view that is recorded when you press the shutter release is somewhat arbitrary.  You may be able to modify this, in a generic sense, in your camera’s settings but we usually adjust these only rarely and it is easier to adjust the pictorial space post hoc, using crop and rotate commands in a photo editing package.  The microscopist is further limited because most microscope stages do not rotate so the orientation of an organism can only be adjusted after the image itself has been collected.  Similarly, those of us who are photographing larger algae have only the small screens on our cameras with which to check images in the field, possibly in the face of inclement weather.  There is no disgrace in some judicious imaging editing once we can examine the image on a large screen, and the rules allow for this, along with focus stacking and stitching, essential tools in the microscopist’s armoury.

What about adjustment of colour and tone?   Bear in mind that colour, in the macro world with which we are most familar is reflected and objects can only reflect those wavelengths that reach them.  That means that colour and tone, in underwater photography especially, is not really a fundamental property of the organism you are photographing.   Move the same alga from a deep location to a shallow one, and it will look different for no other reason than the amount and quality of light transmitted through the water will change.   The microscopist is less likely to deal with reflected light, as the camera will be recording light that has passed through a specimen but, here too, the light is far from natural.  It will depend on the type of bulb, the intensity of light that you are using and the set-up of the microscope itself.  Once again, the colour and tones recorded are not fundamental properties of the specimen.   Under such circumstances, there seems to be no particular reason not to use the “levels” and “curves” options in editing packages to produce an image that is visually pleasing.  The judges are looking for basic authenticity and honesty in the image, so as not to deceive or misrepresent the natural world to the viewer, but there is a wide tolerance around this criterion because, frankly, natural light is, itself, so changeable.

The pair of photographs below illustrate this point well.  I was walking through local woodlands as I was thinking about this post.  May in the UK is the time when woodland floors turn a spectacular violet-blue due to the flowers of the bluebell (Hyacinthoides non-scripta).   I took the upper photograph on my iPhone then walked a few steps into the woodland to remove the dead tree that runs diagonally across the foreground.  I went back to my original position and took another photograph.   No more than 30 seconds elapsed between the two pictures, but the colour balance is completely different.   It may be a product of the metering in the camera itself (I’ve cropped both to show the same scene but the upper image had more bluebells and less woodland than the lower one) and this introduces another source of variation: the oh-so-clever electronics inside even fairly basic cameras that are making decisions on your behalf.

Shincliffe_bluebells_May20

Two images taken within 30 seconds of each other from the same spot in woodland near Shincliffe, Co. Durham, May 2020.  The images at the top of the post show the 2009 and 2010 winners of the Hilda Canter-Lund competition, by Mariano Sirioni and Ernesto Macayo respectively. 

Most scientists assume that photography offers a “truthful” account of the objects that they are recording.   That’s at odds with the approach of critical theorists in the arts and humanities who recognise how many interventions lie between any object and the final image that is presented to third party viewers.   Susan Sontag, for example, challenges the “presumption of veracity” – less of an issue, perhaps, for fine artists but almost everything we think of as “documentary photography” or “photojournalism” is loaded with presumptions by both photographer and viewer, and it is a small step from those disciplines to scientist’s efforts to use photographs as objective evidence in their research.

The Hilda Canter-Lund competition is, however, not about photography as a scientific tool, but as a means of communication.  Appreciating the artificial nature of photography should be a liberation not a constraint: you, as photographer, probably have as accurate a memory of the image you have captured as the jpeg or tiff file that represents the digital record of the moment you released the shutter.   So feel free to open up the file in an editing package and use your discretion to adjust all the factors that were either in-built constraints or impulsive spur-of-the-moment decisions.   And send the final image to us for consideration for the 2020 Hilda Canter-Lund prize.

You can find the rules of the competition at https://brphycsoc.org/hilda-canter-lund-prize/ along with examples of recent shortlists to inspire you.

Reference

Sontag, Susan (1977).  On Photography.  Penguin Books, Hamondsworth.

Other posts on photographing algae

How to win the Hilda Canter-Lund prize

How to win the Hilda Canter-Lund prize (2)

How to win the Hilda Canter-Lund prize (3)(guest post by Chris Carter, twice winner of the competition)

How to win the Hilda Canter-Lund prize (4)

 

Some other highlights from this week:

Wrote this whilst listening to: still working through my resolution to listen to all Bob Dyla’s albums in sequence.   This week I listened to The Basement Tapes, Desire, Hard Rain (much underrated in my opinion) and Street Legal.  Also enjoyed Jagged Little Pill by Alanis Morissette.

Cultural highlights:  The Assistant is an excellent but gruelling film that references the predatory behaviour of Harvey Weinstein but manages to do this almost entirely by inference and implication.

Currently reading:  Tamed by Alice Roberts, about the domestication of plants and animals, is interesting but rather turgid so I’m alternating chapters with Slaves of New York, a 1986 short story collection by Tama Janowitz which I borrowed from my son’s bookshelf.

Culinary highlight:   Baked cod topped with a pesto made from garlic mustard (Alliaria petiolata) foraged from the garden and allotment.

The dark side of the leaf …

Whites_Level_lower_epiphytes

Having mentioned in my previous post that the epiphytes on the top and bottom surfaces of a Potamogeton polygonifolius leaf were different, I have produced a companion piece to the painting I showed in that post.   The new painting is of the lower surface, and shows a greater number of diatoms than are present on the upper surface.  In order to explain why this is the case, it is helpful to look at the structure of the Potamogeton leaves.  The first image, therefore, shows a section through a leaf. It is quite a thick section but we can see the upper epidermis, the palisade mesophyll cells below this, which have plenty of chloroplasts in order to capture the sunlight that the plant needs for photosynthesis.  Below this, we can see parenchymous tissue arranged to create some large internal air spaces which contribute to the leaves buoyancy. Finally, at the bottom, there is a single layer of epidermal cells.   All this is crammed into a thickness of about half a millimetre.

Potamogeton_polygonifolius_leaf_section

Part of a section of a leaf of Potamogeton polygonifolius.  The leaf vein is on the left, thinning to the leaf blade on the right.  The leaf blade is about half a millimetre thick.   The picture at the top of the post shows an artist’s impression of diatoms and Chamaesiphon cf. confervicolus on the lower surface of a Potamogeton polygonifolius leaf. 

 Viewed from the underside, these parenchymous tissues create polyhedronal chambers, ranging from about 100 to 200 micrometres (a tenth to a fifth of a millimetre) along the longest axis.  There are also a few stomata scattered across the leaf surfaces (see the right hand image below).

With this in mind, take a look at my impression of the epiphytes growing on the lower surface of a Potamotgen polygonifolius leaf.   There are a number of cells of Chamaesiphon cf confervicolius, as seen on the upper surface, but there are several cells of the diatom Achnanthidium minutissimum, growing on short stalks, plus a few long, thin cells of Ulnaria ulna, growing in small clusters on the leaf surface (there were a few other species present, but such low numbers that I have not included them here).    It might seem strange to think of two surfaces of a leaf having such different communities of epiphytes but that’s because we’re thinking like large land-dwelling organisms, not like algae.   The longest alga visible in the image of the leaf underside is Ulnaria ulna, at about a 10th of a millimetre in length.  Therefore, to get a realistic impression of the two images, we really need to put a distance of five of these between them, and then pack the gap with chloroplast-rich mesophyll cells inside the Potamogeton leaf.   Allowing for foreshortening, this distance is about five times the height of the image.

Pot_polygonifolius_leaf

The structure of a Potamogeton polygonifolius leaf viewed from the underside.  The left hand image (100x magnification) shows a leaf vein running diagonally across the lower right hand side along with the polyhedron-shaped chambers; the right hand image (400x magnification) shows the outline of one of these chambers superimposed behind the epidermal cells with a stomata with two guard cells visible just above the centre.   Scale bar: 20 micrometres (= 1/50th of a millimetre). 

The epiphytes on the upper surface of the leaf get first dibs at the meagre Pennine sunlight, which then has to pass through the upper layers of the Potamogeton leaf, where the mesophyll cells will continue to feast on the tastiest wavelengths, leaving relatively meagre pickings for the epiphytes that hang around on the underside of the leaf.

Chlorophyll, the molecule that makes plants green, absorbs light over a relatively narrow range of wavelengths – predominately red and blue – and this means that there are plenty of other wavelengths awaiting an organism with different pigments.   Diatoms have chlorophyll, but they also have some carotenoids (principally fucoxanthin) that grabs energy from the green part of the visible light spectrum (which is reflected, rather than absorbed by chlorophyll) and passes it to the cell’s photosynthetic engine.  Having this capability means that they can survive in relatively low light, which is why we see more diatoms on the underside of the Potamogeton leaf than on the top.

And that, best beloved, is the story of how Potamogeton got its epiphytes …

 

Some other highlights from this week:

Wrote this whilst listening to: more Bob Dylan.   I’ve got to the mid-70s, which means the live version of Like a Rolling Stone on Before the Flood plus the great Blood on the Tracks.  Also, as I was reading Ian Rankin, I listened to John Martyn’s Solid Air.

Cultural highlights:  we’re watching the BBC adaptation of Sally Rooney’s Normal People

Currently reading:  Ian Rankin’s Rather be the Devil.

Culinary highlight:   A rather fine vegetarian chilli, from Felicity Cloake’s column in The Guardian last week.   Served with corn bread, using a recipe we got from a hand-me-down American housekeeping magazine during our time in Nigeria.

 

Whatever doesn’t kill you …

Potamogeton_epiphytes_April20

The previous post focussed mostly on the higher plants that I found in the short stream that connects White’s Level with Middlehope Burn.  I mentioned the mass growths of algae that I found growing immediately below the entrance to the adit, but I did not talk about them in any detail, instead spinning off on a tangent while I mused on why the water cress had a purplish tinge.

When I did find time to examine the algal floc, I found it to consist of a mix of three different algae, the most abundant of which was Tribonema viride, but there were also populations of a thin Microspora (not illustrated) and Klebsormidium subtile.   I talked about Tribonema in the drainage from the Hadjipavlou chromite mine in Cyprus last year (see “Survival of the fittest (1)”) and both Microspora and Klebsormidium are also genera that are known to frequent these habitats.  Indeed, there is evidence that the populations that grow in these extreme habitats have physiological adaptations that help them to cope with the conditions.  Brian Whitton, my PhD mentor, led several studies on these adaptations in the streams of the northern Pennines in the 1970s, and Patricia Foster did similar studies in Cornwall at about the same time.   There is probably a mixture of physiological strategies involved, including the production of low-molecular weight proteins, which bind the toxic metals, and the production of extracellular mucilage.  Most of the populations I find in such habitats have a distinctly slimy feel due to the production of extracellular polysaccharides, and it is possible that these play a role in trapping the metal ions before they can get into the cell and cause damage.

Tribonema_viride_WhitesLevel_Apr20

Filamentous algae from the drainage channel below White’s Level, upper Weardale, April 2020.  a., b. & c.: Tribonema cf. viride, showing the characteristic H-shaped cell ends.   d.  Klebsormidium cf. subtile.  Scale bar: 10 micrometres (= 100th of a millimetre).   The picture at the top of the post shows an artist’s impression of Chamaesiphon cf. confervicolus on the upper surface of a Potamogeton polygonifolius leaf. 

I also had a look at the algae growing on the submerged leaves of Potamogeton pergonifolius in the channel between the adit and Middlehope Burn.   One easy way of examining them is to add a small amount of stream water then shake the leaves vigorously in a plastic bag.  The result is a brownish suspension of algae that can be sucked up with a Pasteur pipette and placed on a microscope slide.  When I did this, I found a community that was dominated by a short cyanobacterium, closest in form to Chamaesiphon cf. confervicolus.  The other abundant alga in the sample was Achnanthidium minutissimum, which is often common in minewaters, along with smaller numbers of a few other species.  The total number of species in the sample was just 12, which is low by the standards of streams without metal pollution, but such suppression of all but the hardiest species is another characteristic effect of heavy metal pollution.

I’ve added a “cf” (from the Latin conferre, meaning “compare to”) to my identification of Chamaesiphon confervicolus because this is the closest name, based on a comparison with images in the Freshwater Algal Flora of Britain and Ireland.  However, it is not an exact match.  Whether this is because the metals have strange effects on Chamaesiphon (as we saw for diatoms in “A twist in the tale …”) or whether our knowledge of the species within this genus is imperfect is not clear.  But discretion is the better part of valour in this instance.  Chamaesiphon species fall into two groups: those that live on stone surfaces (see “Survival of the fittest (2)”) and those that live on algae and plants, such as the one we see today (another is illustrated in “More from the River Ehen”).   They consist of a single, elongate but gently tapering cell, attached at one end to the plant and enclosed in a sheath.   The upper end of the filament forms small spherical buds (technically “exospores”).  One reason that I am wary of calling this population C. confervicolus is that most illustrations of this species show a stack of exospores in the sheath, whereas the White’s Level population all had just a single exospore.

Chamaesiphon_confervicolus

Chamaesiphon confervicolus, growing on Potamogeton polygonifolius in White’s Level outflow, April 2020.   Note the exospores at the end of the cell.  f. and g. show the sheath very clearly.  Scale bar: 10 micrometres (= 100th of a millimetre). 

The picture at the top of this post shows an artist’s impression of the Chamaesiphon cf confervicolus on the upper surface of the Potamogeton leaf.   I wanted to get some idea of the size, shape and arrangement of the epidermal and stomatal cells on the Potamogeton leaves and resorted to the tried and tested technique of painting a layer of clear nail varnish onto the leaf surface, then peeling this off when it had dried.  This had the added (and unexpected) benefit of also pulling of the epiphytes, giving some idea of their arrangement on the leaf surface at the same time.   One extra observation that this yielded was that upper surface was dominated by Chamaesiphon, growing in clusters, whilst the lower surface had greater representation of diatoms.   I’ve also tried to portray the chloroplasts in the stomata guard cells.  Plant epidermal cells generally do not contain chloroplasts, as their purpose is to protect the mesophyll cells that are the main centres of photosynthesis.  Guard cells of stomata, however, need energy to open and close the stomata so these are the exception to this rule.  I had not even been sure that I would see stomata on the upper surface of the cell, as these are mostly found on the underside of leaves; however, Potamogeton appears to have stomata on both surfaces.  As ever, there is a certain amount of evidence along with a dose of extrapolation.   Imagined, but not imaginary …

You can find a description of the terrestrial plant life of Slitt Mine and its environs in this post on Heather’s blog.

References

Foster, P.L. (1982).  Metal resistances of Chlorophyta from rivers polluted by heavy metals. Freshwater Biology 12: 41-61.

Harding, J.P.C. & Whitton, B.A. (1976).  Resistance to zinc of Stigeoclonium tenue in the field and the laboratory. British Phycological Journal 11: 417-426.

Robinson, N.J. (1989).  Algal metallothioneins: secondary metabolites and proteins.  Journal of Applied Phycology 1: 5-18.

Say, P.J., Diaz, B.M. & Whiton, B.A. (1977).  Influence of zinc on lotic plants. I. tolerance of Hormidium species to zinc.  Freshwater Biology 7: 357-376.

Sorentino, C. (1985).  Copper resistance in Hormidium fluitans (Gay) Heering (Ulotrichaceae, Chlorophyceae).  Phycologia 24: 366-368.

(Note that Hormidium is the old name for the genus Klebsormidium.  There is an orchid genus called Hormdium and, as this was described first, it takes priority.)

 

Some other highlights from this week:

Wrote this whilst listening to: Bob Dylan’s New Morning and Pat Garrett and Billy the Kid.   Also, Samuel Barber’s Prayers of Kirkegaard.

Cultural highlights:  The Netflix series Unorthodox, about a young woman fleeing a Hassidic community in New York.

Currently reading:  Agatha Christie’s A.B.C. Murders.

Culinary highlight:   Arroz con leche (Spanish rice pudding) served with peaches poached in madeira.

A reasonable excuse for exercise ..

High_Mill_falls_Apr2020A redefinition of the travel restrictions hereabouts means that “driving to the countryside and walking (where far more time is spent walking than driving)” it is now “likely to be reasonable” within the terms of Regulation 6 of the The Health Protection (Coronavirus, Restrictions) (England) Regulations 2020. That means that, rather than plan another post about the fascinating ecology of Lough Down, I can look a little further afield.   As both Heather and I are writing chapters for a forthcoming book on the Natural History of Weardale, we turned our eyes to the hills, largely for exercise and a change of scenery, but also as part of our background research for these chapters.

We parked the car at Westgate and followed a path alongside Middlehope Burn, a tributary of the Wear with a long history of lead mining and, as such, a case study in how man has shaped the ecology of Weardale, both terrestrial (Heather’s domain) and aquatic.  The first part of the walk is through Slitt Wood, where the stream cascades over a series of low step-like waterfalls, alternately sandstone and limestone, illustrating the bedrock geology of the area.   The air is full of birdsong and there are patches of primroses feasting greedily on the light that is still plentiful on the forest floor at this time of year.   However, this idyll is short-lived as, passing through a gate we emerge into a grassed area surrounded by derelict mine buildings.  Early on a Saturday morning in the midst of the pandemic, we have the place to ourselves and it is a struggle to imagine this place as a busy industrial site.   Similar sites are scattered throughout Weardale and the surrounding dales; all are now closed but once they would have employed large numbers of people.  There would have been the miners, working underground, of course, but also gangs of people (including women and children) breaking down and sorting the ore as it was brought to the surface, plus ancillary workers involved in construction, both above and below ground.

A couple of hundred metres beyond the site of the main shaft at Slitt Mine, I spot an adit (a shaft driven horizontally into a hillside) and make my way towards it.  These are intriguing habitats for ecologists interested in the interactions between man and nature and I was intrigued to see what was growing in this one, White’s Level.  The mine’s levels and shafts act as natural drainage channels, collecting water that has percolated through the rocks but, because the miners have driven the levels along the mineral veins, the water comes into contact with lead, zinc and cadmium during the course of its underground journeys, emerging with concentrations far in excess of those deemed safe by toxicologists.  However, the channel immediately downstream of the entrance of White’s Level was lush with vegetation.   I could see thick wefts of filamentous algae giving way to beds of water-cress (Rorippa nasturtium-aquaticum) and bog pondweed (Potamogeton polygonifolius).  The latter two were surprising as, in my experience, most of the streams draining north Pennine adits are dominated by algae rather than by higher plants.

Whites_Level_April20

The stream flowing from White’s Level to Middlehope Burn, April 2020.  The left-hand image shows the beds of water-cress very clearly whilst the right hand image shows the filamentous algae growths immediately below the entrance.   The picture at the top of the post shows Middlehope Burn at High Mill Falls, just upstream from Westgate.

The water cress had a distinctive purplish tinge which is probably a response to stress.  We’ve encountered this type of colour-change in response to stress elsewhere (see “Escape to Southwold”).   In this post, and in “Good vibrations under the Suffolk sun …” I talked about how plants have to regulate the amount of energy from sunlight in order that their internal photosynthetic machinery is not overwhelmed.  Those posts were both written after a hot weekend in July, but this was a chilly and overcast April morning in the Pennines where the prospect of plant cells being overcome by heat seems faintly ludicrous.   Here, instead, is my alternative hypothesis.

Although White’s Level and the other mines in the northern Pennines were driven by the demand for lead, lead is a relatively insoluble element and zinc, which is found alongside the lead in the metal-rich veins of the northern Pennines, is more soluble and, therefore, has a greater toxic influence on the plants and animals in these streams.  Zinc affects the metabolism of plants in several ways, one of the most important of which is to reduce the effectiveness of the chlorophyll molecules which are responsible for photosynthesis.  It does this by nudging the magnesium atom, which lies at the heart of every chlorophyll molecule, out of place.

Whites_Level_macrophytes_Apr20

Macrophytes in the stream flowing from White’s Level to Middlehope Burn, April 2020.   Left: Potamogeton polygonifolius; right: Rorippa nasturtium-aquaticum.

What this does, then, is alter the balance of the equation that tries to balance energy inputs and photosynthesis.   If your chlorophyll molecules are hobbling along, then the point at which they are overwhelmed by even the meagre Pennine sunlight shifts so that  the need for the plants to manufacture their on-board sunscreen kicks in sooner.   Just a hypothesis, as I said: if you have a better explanation, please let me know.

A few hundred metres further on, there is another lush growth of water cress in the stream flowing out of another adit, Governor and Company Level, this time even extending beyond the metal grille designed to keep the curious from harm.  I most associate watercress farms with the headwaters of chalk stream, which are characteristically spring-fed and, therefore, have very stable conditions.   The adits of the northern Pennines are, this respect, very similar to springs insofar as their flow, temperature and chemical conditions vary little over the course of a year.   In that respect, it is perhaps less of a surprise that we find water cress growing so prolifically here.   The zinc, admittedly, is a complication we don’t find in most springs but, that apart, the adits could be thought of as man-made springs, creating a series of almost unique, but largely overlooked habitats.

In the next post, I’ll talk about the algae that I found in the White’s Level channel.

Governor_Company_Level_Apr20

A prolific growth of water cress in the drainage channel below Governor and Company Level, April 2020. 

Some other highlights from this week:

Wrote this whilst listening to: Still working through Dylan’s back catalogue: John Wesley Harding, , Nashville Skyline and Self-Portrait, the latter a blip in an otherwise superb run of albums.   Next up is New Morning but I want to re-read the chapter in Dylan’s Chronicles Volume One where he describes the genesis of this album before listening.

Cultural highlights:  My book group looked at Pride and Prejudice but, being deep into The Mirror and The Light, I did not had time to read this.   We watched the 2005 film version starring Kiera Knightly instead.   Turned out that three of the six participants in the book group had also watched the film the night before our Zoom meeting, rather than (re-)reading the book itself.

Currently reading:  Finally finished The Mirror and The Light which was, definitely, worth the effort.  Started Kate Atkinson’s Big Sky.

Culinary highlight:   Home-made tortellini filled with mushroom paté, served with a consommé made from turkey stock from the freezer.  Culinary ambition hereabouts always goes sky high in the week of the MasterChef finals.