The end of the road?

My final post for the year has traditionally been a round-up of the previous 12 months and a look ahead to the year to come.  This year, however, with the publication of the UK-EU trade agreement on Christmas Eve, there are serious matters that need to be considered.   The UK leaves the EU at 11pm on 31 December 2020 with, if the press releases are to be believed, reassurance that high environmental standards will be maintained, thanks to key clauses in the agreement (“Title X: Good Regulatory Practice and Regulatory Co-operation”).  Let’s put this to the test, using the “thoughtful reform” set out by Environment Agency Chief Executive James Bevan earlier this year (see “But …”).

Bevan’s call for “thoughtful reform” seemed to dilute the “one out, all out(1OAO) rule” that is at the heart of the Water Framework Directive, so let’s see how this might be handled under the terms of the trade deal.   This is not about the pros and cons of the 1OAO rule, only about whether a system that deviated from the 1OAO rule could be construed as violating the terms of the trade deal.

The first clause of the General Principles under this Title is: “Each Party shall be free to determine its approach to good regulatory practices under this Agreement in a manner consistent with its own legal framework, practice, procedures and fundamental principles49 underlying its regulatory system.”.   So long as the UK has appropriate primary and secondary legislation in place, in other words, the 1OAO rule is fair game.   Let’s read on.

Chapter 7 of this Title deals with Environment and Climate and Article 7.2 deals specifically with non-regresssion (“A Party shall not weaken or reduce, in a manner affecting trade or investment between the Parties, its environmental levels of protection or its climate level of protection below the levels that are in place at the end of the transition period, including by failing to effectively enforce its environmental law or climate level of protection”).   Most ecology professionals would regard weakening the 1OAO rule as “regression” but does it affect trade or investment?   

The next clause read: “The Parties recognise that each Party retains the right to exercise reasonable discretion and to make bona fide decisions regarding the allocation of environmental enforcement resources with respect to other environmental law and climate policies determined to have higher priorities, provided that the exercise of that discretion, and those decisions, are not inconsistent with its obligations under this Chapter”.  So maybe the UK government could argue that, regrettable though it may be to ditch the 1OAO rule, they are only doing this to strengthen other aspects of environmental protection.   

So let’s hypothesis that the 1OAO rule is scheduled to be ditched as part of a post-Brexit overhaul of environmental protection policy for the reasons outlined above but that the EU cries “foul”.  What next?   We skip several paragraphs until we reach Article 7.7 Dispute Settlement.  The text goes on to say: “The Parties shall make all efforts through dialogue, consultation, exchange of information and cooperation to address any disagreement on the application of this Chapter”.   If that doesn’t sort it out, then there are three remedies available: Articles 9.1 [Consultations], 9.2 [Panel of experts] and 9.3 [Panel of experts for non-regression areas].  Article 9.1 seems to be a continuation of the reference to “all efforts” in 7.7 whilst the other two Articles refer to a Panel of Experts.  These will consist of three people with “specialised knowledge or expertise in …  environmental law”, which seems to point to lawyers rather than ecologists in our case study, and they should be independent of both UK, EU and Member State governments.   They can receive written submissions from persons with relevant specialised knowledge and they produce a report which will determine whether or not the UK proposal to weaken 1OAO are contrary to the terms of the deal.  

Let’s say the panel of experts decides that the UK’s actions contravene the non-regression clause but the UK government disagrees.   At this point, an arbitration procedure starts up with, at the end, a tribunal (legal experts wholly independent of UK and EU courts) delivering a verdict.  If that finds against the UK, then there is the option of “suspension of obligations” (meaning, I presume, that the EU introduces some quid pro quo sanctions against the UK).   However, there seem to be plenty of ways for a competent government lawyer to game the system well before it reaches these latter stages so the 1OAO rule is, I suspect, doomed.  

This is all, I hasten to add, hypothetical: the 1OAO rule is a convenient pawn with which to test the new system largely because the Environment Agency have already signalled their intent.  The 1OAO rule is, let’s be honest, far from perfect.   The more general lesson would seem to be that whilst ecology and biodiversity standards that we inherit from the EU appear to be protected by the trade deal, in fact there are enough loopholes to make them extremely vulnerable.   Maybe we are naïve to expect more: this is a trade deal after all and the focus is on aspects of environmental protection that will affect competitiveness.   For every other aspect of safeguarding our environment and biodiversity, we are on our own …

Some other highlights from this week:

Wrote this whilst listening to:  Adrianne Lenker (of Big Thief)’s songs and instrumentals and Sing Me Home by Yo-Yo Ma and the Silk Road Ensemble

Cultural highlights:  Revisiting old films on the BBC iPlayer, including The Godfather and Tamara Drew.

Currently reading:   Rodham, by Curtis Sittenfeld: a novel describing an alternative future in which Hilary never married Bill Clinton.   Ennerdale Water makes a brief entrance.

Culinary highlight: Christmas Dinner, of course: roast turkey, potatoes roasted in goose fat, brussels, parsnips, gravy, cranberry sauce, bread sauce, Christmas pudding, brandy butter …

As old as the hills ..

I need to start with a confession: fieldwork in Cumbrian streams in December has a few drawbacks, not least of which is the water temperature.  Picking up boulders from a stream involves plunging your arm into cold water.  I’ve tried different sorts of gloves, but these inevitably result in a loss of dexterity and, unless the air temperature is really low, it is better to grit your teeth, roll up your sleeve and make sure that there is a warm fleece waiting bankside when you finish. 

This invariably means that my encounters with the submerged plants in this streams are brief and it is easy to miss features of interest. Nonetheless, on my most recent visit to the River Irt  a couple of weeks ago, I noticed some dark spots on some boulders that, despite the temperature, required a closer look.   Given the constraints of fieldwork under these conditions, I was not even sure at first whether I was looking at algae or moss.   It was only when I was back in my warm study, viewing the pictures on a big screen and with my samples teased out in a Petri dish that I was able to work out what I was seeing.   It was actually an acrocarpous moss (name, at present, not known) but accompanied by (and only just visible with the naked eye) tufts of Cyanobacterial filaments at a few points along the stem.   

A submerged boulder in the River Irt, December 2020.  Dark patches are mosses with associated cyanobacteria (and some young filaments of Lemanea fluviatilis) and green patches are mostly Mougeotia, Spirogyra and Zygnema.  The picture at the top of the post shows Cinderdale Bridge on the River Irt.  

I’ve encountered cyanobacteria associated with mosses in this area in the past (see “River Ehen … again”) and initially assumed that this was the same genus, Tolypothrix.  However, a closer look showed this not to be the case.  The lower image shows the broad arrangement of cyanobacterial filaments, with a row of cells (the “trichome”) lives within a thick sheath and then, in the upper image, two filaments appear to collide and veer off out of the sheath.  That’s called a “false branch” in cyanobacterial jargon: “false” because the trichome itself doesn’t branch even though the whole filament looks like it has branched.  False branches are a characteristic of a relative of Tolypothrix, Scytonema.   I’ve reported on Scytonema from this catchment before (see “Close to the edge in Wastwater“) but this species is different in both habitat and appearance.  The one I wrote about before was attached directly to the rock and had sheaths that were heavily pigmented whereas this species (probably Scytonema crispum) grew on mosses in the river that flows out of Wastwater and had little or no pigmentation in the sheath. 

Scytonema crispum from the River Irt at Cinderdale Bridge, December 2020.  Scale bar: 20 micrometres (= 1/50th of a millimetre)

These alga were growing in a river that flowed through some spectacular landscapes: the Wastwater screes rise up dramatically from the south-eastern shore and, at the northern end of the lake, the peak of Scafell Pike, England’s highest mountain is often visible.   These are composed of rocks of the Borrowdale Volcanics group, dating from the Ordovician era, approximately 450 million years ago.   That means that they are about twice as ancient as the dinosaurs.  By contrast, fossil remains of the cyanobacteria have been found from rocks that are 3.5 billion years old.  That means that, relatively speaking, the mountains surrounding Wastwater are mere babies compared with these algae.   Of course, cyanobacteria will have evolved over this time; however,  the Borrowdale Volcanics have been weathered, faulted and folded over the millenia too.   So, so long as you remember that change is the only constant in both geology and biology, these simple, largely inconspicuous filaments are, quite literally older than the hills.

Some other highlights from this week:

Wrote this whilst listening to:  RM Hubbert and Aidan Moffat’s Ghost Stories for Christmas.   Deliciously dark Christmas album from 2018.   But not as dark as Lou Reed’s Christmas in February.

Cultural highlights:  The film Ma Rainey’s Black Bottom, with Viola Wilson and Chadwick Boseman

Currently reading:   just finished The First Christmas by Marcus Borg and John Dominic Crossan and just starting Merlin Sheldrake’s Enchanted Life, about the fascinating world of fungi.

Culinary highlight: made my annual batch of Christmas ice cream, with mincemeat and plenty of cinnamon, cloves and nutmeg.  Served this with pears poached in ginger wine and port and some 

Curried diatoms?


Last week’s musing on mayfly anatomy has crystallised this week into a finished image of a nymph of Baetis rhodaniifeeding on stream algae.   One mandible is visible on the left cutting through a mixture of green algae and diatoms whilst a glossa – the nymph’s equivalent to a tongue – probes the biofilm at the centre right of the image.   At the back, you can see the nymph’s right foreleg extending up above the stone surface.   The algae in the picture are common in Lakeland streams: Gomphonena acuminatum and Tabellaria flocculosa along with the green alga Ulothrixon the left foreground, as an example of the thicker biofilms giving way to, on the right, an assemblage typical of heavily-grazed biofilms, with Cocconeis lineata prominent.    

Cocconeis lineata is often prominent at a location in Croasdale Beck, a small tributary of the Ehen that we visit regularly.  This is also a location where we often see large numbers of mayfly grazers as well as other invertebrates that can feed on algae (see “Blind to the obvious …”). It is often cited as a diatom that is resistant to grazing due to its low profile.  However, the story is not quite so straightforward as that as there is an unusually large number of broken valves, suggesting that the nymphs, even if they do not eat as many of the Cocconeis as they do other algae, do manage to damage them in the process.  Not only were there significantly more broken than intact valves but also the upper valves were more likely to be damaged than the lower ones, which would be in line with expectations, given what we know of how mayfly nymphs feed.   

Cocconeis lineata from Croasdale Beck, Cumbria, September 2020.  Top two rows: rapheless (upper) valves; bottom row: raphe (bottom) valves.  Scale bar: 10 micrometres (= 1/100th of a millimetre).  

The literature often refers to “selective grazing” and these illustrations may offer us a way of thinking through what this means.   Firstly, from the point of view of a mayfly nymph or a snail, the scale difference, even between the mouthparts and the algae, means that this only going to operate at a fairly coarse scale.  If grazing is selective then, to use a human analogy, it means choosing a restaurant serving French rather than Indian food rather than preferring broccoli to carrots.    Most of the species within biofilms are too mixed up together for us to contemplate an organism the size of an Ecdyonurus or Baetis nymph selecting one species over another (the situation may be different for smaller grazers such as the Chironomidae).   It is easier to conceive of the nymphs sensing the gross composition of a biofilm – whether there are lots of succulent young filaments of green algae or less nutritious cyanobacteria, for example. 

Broken valves of Cocconeis lineata from Croasdale Beck, September 2020.   Top row: rapheless (upper) valves; bottom row: raphe (bottom) valves.  Scale bar: 10 micrometres  (= 1/100th of a millimetre).  

There is, however, some evidence of diatoms producing compounds that deter grazers, and also that this trait varies between species.   Most of the studies, to date, come from the marine environment rather than streams so we need to extrapolate with care.  One paper does include some freshwater diatoms in a survey of aldehyde production although none tested positive.   That does not mean that freshwater diatoms do not produce aldehydes: one of the problems is that the algae that are easy to culture are often the fast-growing unfussy species and these tend to be the ones on which studies are focussed.   My suspicion is that aldehyde production is more likely to be found in the less abundant species which divert some of their energy to this rather than to simply growing and dividing.   A diverse community that includes a few aldehyde producers might be less attractive to grazers than a community where one non-aldehyde producer dominates.   Therefore, the greater the success of a diatom, relative to other algae, the more vulnerable it will be to grazers.  Crop back this prolific grower and the aldehydes will be more noticeable to the sensila on the nymph’s glossa.   It is another variant of the cat-and-mouse games I described in The stream easts itself … with a similar end-result of justifying diverse assemblages.

To extend my analogy of humans preferring a French restaurant to an Indian restaurant, one plant-based constituent of Indian meals (Capsicum spp.) produces a secondary metabolite which itself probably evolved to deter mammalian grazers (capsaicin) that is detectable even at relatively low concentrations relative to other ingredients.   Basmati rice is, as it were, protected from grazing by anyone who dislikes spicy food, even though it is not naturally spicy itself.  Several other common ingredients of Indian cuisine (potato, tomato, aubergine) are from the same family as Capscicum spp but are not spicy so, once again, we can extend this to diatom-dominated biofilms and speculate that a few species could provide enough aldehyde to protect the many, and that aldehyde production does not need to be a general response of all diatoms.   

There might, of course, be mayfly equivalents of groups of lads who role up at their local Tandoori restaurant at the end of a drinking session on a Saturday night determined to eat the hottest curry on the menu, but there I go again: stretching a metaphor to breaking point and then giving it a gentle push into the realm of the absurd.  Regular readers should be used to this by now …


Wichard, T., Poulet, S.A., Halsband-Lenk, C., Albaina, A., Harris, R., Liu, D. & Pohnert, G. (2005).  Survey of the chemical defence potential of diatoms: screening of fifty one species for alpha, beta, gamma, delta-unsaturated aldehydes.  Journal of Chemical Ecology 31: 949-958.

Willoughby, L.G. (1988).   The ecology of Baetis muticus and Baetis rhodani (Insecta, Ephemeroptera) with special reference on acid water backgrounds.   Hydrobiology 73: 259-273.

Also: a poster and an abstract from Gary Caldwell’s research group at the University of Newcastle:  and

Some other highlights from this week:

Wrote this whilst listening to:  Tom Waits and, in acknowledgement that Christmas is just two weeks away, Christmas in Puebla, 17th century Mexican Christmas music from Siglo de Ora.  Come to think of it, my Tom Waits session started on a Christmas theme, with “Christmas Card From A Hooker in Minneapolis”.  That’s about as festive as my Christmas playlist gets, I’m afraid …

Cultural highlights:  The well-received film Saint Frances, written by and starring Kelly O’Sullivan.   We’ve been waiting to see this for some time and it has finally arrived on streaming services in the UK.  

Currently reading:   The Book of Lost Things by John Connolly, a rare excursion, for me, into fantasy fiction.  

Culinary highlight:    Homemade Spirulina pasta filled with smoked salmon, cream cheese and dill served in a lobster bisque (the latter, I have to confess, from a tin).  

Flatpack flies …

Emboldened by last week’s foray into the world of invertebrate ecology, I thought I would push ahead with a picture of a different mayfly nymph grazing on algae as a “compare and contrast” exercise.   Mayflies form a distinct order and just as we would not expect a human to behave similarly to a gibbon or baboon, so we should not assume that members of different families within the Ephemeroptera feed in the same way.  Trying to convey this pictorially at the scale of the algae on which mayflies graze, however, requires quite detailed knowledge of the mouthparts of different species.  

My explorations of how Baetis rhodanii, another important grazer, feeds led me to a 1950 paper by T.T. (“Kitten”) Macan, an entomologist at the Freshwater Biological Association.  In this paper he lays out the mouthparts of various species of Baetis almost as if they were the parts in an Ikea instruction manual (come to think of it, “Dagslända”, the Swedish word for “mayfly”, would make a very plausible name for an Ikea product).

Structures of Baetis pumilus from Macan (1950).   Mx: maxillae; H: hypopharynx; L: Labium; Md: mandibles; 1-7: gills, numbered from the front; f,m,h: fore, mid and hind legs.

We do not get much of a sense from these drawings, however, of how they fit together and, more importantly, how they interact to manipulate food into the nymph’s mouth.   The same is true for many photographs of Baetis rhodaniilargely, it must be said, because the mouthparts are on the underside of the head and, therefore, difficult to photograph when the organism is alive.   I’ve included two labelled photographs taken from Kenny Gifford’s excellent website The Microscopic Life of Shetland Lochs which, along with Macan’s scale drawings, give me some raw material from which to plan a painting of a Baetis nymph feeding on algae.

The head of a nymph of Baetis rhodanii from Fitch Burn, Shetland Mainland, collected and photographed by Kenny Gifford ( with labelled mouthparts. The head is about a millimetre across.

Some of the mouthparts are relatively straightforward to interpret, as they have direct mammalian analogues, and because Baetis feed by chomping (for want of a better term) on the algae on a rock surface. So we can see a basic apparatus of upper and lower jaws (maxillae and mandibles respectively) plus upper and lower lips (labrum and labium respectively).  Where mayfly nymphs differ from humans is in the various “palps” that accompany the mouthparts.   In the previous post I mentioned how the labial palp of Ecdyonurus was adapted into a brush-like appendage that swept the algae towards the mouth.  In the case of Baetis, the key feeding action is the downward thrust of the mandibles rather than the brushing of the labial palps, so these are not so distinctive.

One other important characteristic visible in the illustrations are the glossae and paraglossae, extensions of the labium roughly analogous to our tongues.   These, like our tongues, are equipped with sensory organs that, presumably, have some control over the nymph’s feeding behaviour.   Baetis nymphs, unlike humans, make little or no use of vision when feeding, so these other senses are particularly important.   The head of the Baetis nymph is about a millimetre across, or between 50 and 100 times larger than the organisms on which it feeds, to give you some idea of scale. 

A different view of the head of a Baetis rhodanii nymph with some different features labelled.  Again, the head is about a millimetre across.  Photographed by Kenny Gifford.

All of this is, as I said at the start of the post, preparation for a painting of Baetis grazing on stream algae.  This preoccupation with anatomy as a precursor to art puts me in noble company (see “I am only teaching you how to see …”) even if my intentions are rather more modest than Leonardo’s.   The point where we meet is also, however, a launchpad for the imagination: at some point we need to couple the anatomical evidence with a dash of imagination in order to bring viewers a little closer to experiencing life on a different scale. 


Gattolliat, J.-L. & Sartorini, M. (2008).  What is Baetis rhodani (Pictet, 1843) (Insecta, Ephemeroptera, Baetidae)? Designation of a neotype and redescription of the species from its original area. Zootaxa 1957: 69-80.

Macan, T.T. (1950).  Descriptions of some nymphs of the British species of the genus Baetis (Ephem.).  Transactions of the Society for British Entomology 10: 143-166.

Some other highlights from this week:

Wrote this whilst listening to:  When Strangers Meet by Yo-Yo Ma and the Silk Road Ensemble which includes a divine interpretation of Filippo Azzaiole’s Chi passa per’sta strada (“those who pass along this street”) played on oriental instruments.   And Odin’s Raven Magic by Sigur Rós.

Cultural highlights:  The National Theatre production of The Three Sisters, adapted from Chekov’s original by Inua Ellams.

Currently reading:   still Wanderlust: A History of Walking, by Rebecca Solnit. 

Culinary highlight:    Mushroom risotto made with spelt rather than rice and served with creamed spinach and homemade crispbread.