Sticky water …

It seems strange to be writing about an alga that thrives in winter in the middle of one of Britain’s rare heatwaves but I came across two papers recently that shed some light on the ecology of Ulothrix zonata.  This is a species that has intrigued me for some time, having a very distinct preference for times of the year when our rivers are at their coldest and I have tried to unravel the reasons for this in some earlier posts (see “Bollihope Bhavacakra” and “The intricate ecology of green slime …”).

The lead authors on these papers are based at Irkutsk, beside Lake Baikal in Siberia, so are in a good position to contemplate the effects of cold conditions on algae.   Whereas I complain about plunging my hand into cold water in northern England to collect Ulothrix zonata, they had to Scuba dive under the ice of Lake Baikal in water only just above freezing point.  They have found two adaptations in the Lake Baikal populations of U. zonata to cold conditions.  The first of these is that the ratio of polyunsaturated to saturated fatty acids are higher in these populations than in those of other Ulothrix species.   This sounds as if it could be an algal equivalent of the “blubber” that insulates sea mammals but the truth is rather more mundane: it is part of a series of adaptations of the cell membrane that allows the organism to keep functioning despite the harsh conditions.

Living underwater is, in many ways, the easy option for a plant in Siberia, where the average outside temperatures in winter are less than -10 °C, and the record low is almost -50 °C.  Terrestrial plants adapt to such harsh environments simply by shutting down operations.   However, whilst the surface layers of Lake Baikal freezes, life below the ice can continue and there are several studies about the rich algal life within this enormous lake (which contains a fifth of the planet’s fresh water).   Enough sunlight can penetrate through the ice to sustain growth, albeit at a slow rate but, on the other hand, the cold water creates problems of its own.   In particular, the density of water increases as temperature drops, making it more viscous.  We might not notice that cold water is more gloopy than warm water but that is because how we experience viscosity is partly a function of our size.  What might be an insignificant change to a human can be a big deal to a microscopic alga.

The cell membrane is composed largely of lipids and, like margarine, these are soft in warm environments (such as frying pans) but hard in cold environments (such as refrigerators or Lake Baikal).  The problem for cells is that there are other molecules embedded in the lipid layers which help the cell obtain the raw materials it needs, and these will not be able to function if the lipids in the membrane are too rigid.   Molecules of saturated fats pack together more compactly than those of polyunsaturated fats which means that a membrane with lots of these is more rigid than one with a high ratio of polyunsaturates.   Consequently, if an organism is to thrive in cold environments then it is beneficial for it to have a high ratio of polyunsaturated to saturated fats in the lipid molecules.

Water is one of the molecules that submerged algae need to shift into their cells to keep their cellular machinery running as this is one of the raw materials of photosynthesis.   There is no shortage of water on the outside of the cell.  However, having a membrane composed largely of hydrophobic lipids means that this is not straightforward and one of the molecules that is embedded in the lipids belongs to a group of proteins called “aquaporins”.  These are shaped in such a way that there is a narrow channel in the centre (like the hole in a doughnut) through which water molecules can pass in single file.

Aquaporins are well known in animal, plant and bacterial cells but it is only recently that they have been found in algae too.   Aleksey Permyakov and colleagues showed that Ulothrix zonata populations from Lake Baikal and streams in the vicinity had more aquaporins in winter than the summer, which they interpreted as an adaptation that ensured a steady supply of water to the cell despite the higher viscosity of the water.  This is also the first time that algal cells have been shown to be able to regulate the amount of aquaporin in membranes in response to their environment.

These two observations together suggest how cold-tolerant algae may have to invest some of their hard-earned energy in modifying their membranes to help them thrive.  I suspect that this is part of a complex network of interactions here: survival in such extreme conditions is possible because the slow rate of growth in very cold water is offset by an even slower rate of grazing and other processes which remove algal biomass.  Diverting energy and resources to make more aquaporins, in turn, means that photosynthesis is not limited by a shortage of raw materials.   It is a fine balance but, if an organism can get this right, then there is an opportunity to thrive with relatively little competition from other organisms.  It is another reminder that ecology is a science that depends on a 365 day perspective and that we should not assume that a few fieldtrips when the weather is most clement will reveal all of its riches.

References

Osipova, S., Dudareva, L., Bondarenko, N., Nasarova, A., Sokolova, N., Obulinka, L., Glyzina, O. & Timoshkin, O. (2009).  Temporal variation in fatty acid composition of Ulothrix zonata (Chlorophyta) from ice and benthic communities of Lake Baikal.  Phycologia 48: 130-135.

Permyakov, A., Osipova, S., Bondarenko, N., Obolinka, L., Timoshkin, O., Boedekker, C., Geist, B. & Schäffner, A.R. (2016).  Proteins homologous to aquaporins of higher plants in the freshwater alga Ulothrix zonata (Ulotrichales, Chlorophyta).  European Journal of Phycology 51: 99-106.

The photograph at the top shows Ulothrix zonata growing on the bed of the River Wear at Wolsingham, Co. Durham in February 2009.

Hilda Canter-Lund competition shortlist 2017

The shortlist for the annual Hilda Canter-Lund competition to find the best algal photograph has just been uploaded to the British Phycological Society website and here is a quick guide to the images.  No less than three previous winners have made it to the shortlist again, along with three newcomers, so it looks like being a particularly intriguing year.

2013 winner Chris Carter has made it to the shortlist for the fifth time with an apical view of the desmid Pleurotaenium coronatum var. robustum with an image that combines aesthetics and technical ability in his own inimitable manner (above left).   The desmid genus Pleurotaenium typically has cylindrical cells several times longer than wide, so getting a good image of one end of a cylinder that is about 1/20th of a millimetre in diameter is quite an achievement.   He is joined on the shortlist by 2016 winner Tiff Stephens, who switches style this year to offer a macroscopic view of female reproductive cells of the subtidal red seaweed Bonnemaisonia clavata, collected off the coast of Vancouver Island in Canada (above right).   The prominent branchlet in the centre-right with its own side branches is 1.5 mm long.

John Huisman shares with Chris Carter the honour of being the most shortlisted photographer in the competition, with five nominations including the winning entry in 2014.   His image this year shows the green alga Ulva stenophylloides, at the centre of a diverse assemblage (above left), photographed whilst snorkelling off the coast of Western Australia.   Heather Spalding, by contrast, makes her first appearance on the shortlist, with a view of Chara zylanica beds in a brackish lagoon in Hawaïi (above right).  Note the small snail making its way across the plants in the foreground, reminding us of the important role that macroalgae play in structuring ecosystems.

We go back to Australia – the D’Entrecasteaux Channel in Tasmania actually – for the next entry: Luis Henriquez’s image of a young plant of the brown alga Carpoglossum confluens emerging from a bed of Caulerpa trifaria (above left). As well as providing a striking image, Luis’ image also tells a story of marine eutrophication as the slow growing brown algae such as Carpoglossum are struggling to compete with the fast growing green algae such as Caulerpa.   Finally, Alizée Mauffrey brings a completely different style to the competition, with a collage of images of seaweeds exhibiting different functional traits (above right).   As well as telling a story about how different morphological, phenological and physiological traits combine to equip each species to inhabit a particular niche, Alizée also creates a pleasantly abstract composition.   She is also the first person to submit an image produced using a flatbed scanner rather than a camera (for more examples of this technique, see An Ocean Garden by Josie Iselin).

This shortlist is unusual in that there is only a single true micrograph and a single freshwater alga (both represented by Chris Carter’s image).   A number – using both the light microscope and scanning electron microscope – were submitted but the judges who selected the shortlist felt that most did not quite make the grade.  It was a close call in a couple of instances (and, in at least one case, some minor adjustments to contrast might have persuaded us) but that is the sad truth.  It may simply be that taking a really good image using a high power microscope is a more technically demanding task than photographing macroalgae in situ?   If nothing else, this does show just how good a photographer Hilda Canter-Lund was.

The final step in the competition is for the council of the British Phycological Society to vote for the winning entry.  After that, a second (but equal) prize will be awarded for the best of the shortlisted entries in a contrasting style (i.e. a micrograph is a photo of a macroalga wins and vice versa).   Both winners should be announced within the next couple of weeks so keep an eye on www.brphycsoc.org for the announcements.  And, while you are there, browse through the archives of pictures that we’ve accumulated since the competition started in 2009 and enjoy some of the remarkable and beautiful organisms that they portray.

Sea of puddles?

I took this photograph of the Aral Sea (“Sea of Islands”) from the cabin window of our flight from Tashkent to London back in April.   The atlases which fed my young mind back in the sixties and seventies have changed enormously, but it is mostly political boundaries that have shifted, particularly in this part of the world.   There are few instances where the physical landscape has changed on quite such a scale as the Aral Sea which has largely disappeared from our maps.  This photograph was remarkable because you can actually see water: most of the Aral Sea is now just desert.

The Aral Sea was fed by two rivers: the Amu Darya – the Oxus of antiquity – and the Syr Darya. The latter was fed by the streams that flow down from the Tien’shan mountains (see “Theme and Variations”); the former rises in the Pamirs in northern Pakistan and then forms the border between Afganistan and Tajikistan before flowing through Turkmenistan and Uzbekistan to the Aral Sea.

Or, at least, that is what used to happen.   The story of the decline of the Aral Sea is a tale that puts most of the concerns about loss of connectivity of western European rivers into the shade.   In the 1960s, Soviet planners decided to use water from the Syr Darya and Amu Darya (“darya” is the Persian word for “river”) to irrigate the semi-arid lands of central Asia in order to grow crops such as cotton.   Not only did this reduce the flow of the rivers substantially, but poor design of the irrigation channels meant that most of the water did not get to the crops that it was meant to sustain.   The reduced flow of fresh water into the Aral Sea caused it to both shrink and become more saline (it is now as salty as the Dead Sea, according to some accounts).   In 1987 the lake split into two separate bodies, and the dried-up area between became the Aralkum desert.

It is a salutary story that, according to the limited research that I have been able to do on the Internet, wholly avoidable.  The Russian attitude to central Asia in the 19th century mirrored that of European power’s approaches to their colonies in Africa and Asia, with a mixture of geo-political manoeuvring and economic motives.  These attitudes were inherited by the Soviets in the 20th century and, even though experts predicted the dire consequences for the Aral Sea, the irrigation scheme was fixed into the Soviet’s five year plans and no-one dared contradict the Politburo’s decisions.

What is the relevance of this to us?   Only that we have just seen the appointment of a Secretary of State for Farming, the Environment and Rural Affairs who said, not much more than a year ago: “people in this country have had enough of experts”.

A tale of two diatoms …

I’ve been writing about the River Ehen in Cumbria since I started this blog, sharing my delight in the diversity of the microscopic world in this small river along with my frustrations in trying to understand what it is that gives this river its character.   We know that the presence of a weir at the outfall of Ennerdale Water has a big influence so, in 2015, we started to look at a nearby stream, Croasdale Beck (photographed above), which is similar in many respects but lacks the regulating influence of a lake and weir.  Maybe, we reasoned, the differences we observed would give us a better understanding of how the regulation of flow in the River Ehen influenced the ecology.

Broadly speaking, any kind of impoundment – whether a natural lake or an artificial reservoir – removes a lot of the energy from a stream that might otherwise roll stones, move sediment downstream and, in the process, dislodge the organisms that live there.   We noticed quite early in our studies, for example, that Croasdale Beck generally had less algae growing on the stones than in the nearby River Ehen, and also that the algal flora here was less diverse.

There were also some quite big differences in the algae between the two streams.  I wrote about one of the Cyanobacteria that are found in Croasdale Beck in “A bigger splash …” but there are also differences in the types of diatoms found in the two streams.  Most diatomists think about ecology primarily in terms of the chemical environment within which the diatoms live but I think that some of the differences that I see between the diatoms in the River Ehen and Croasdale Beck are a result of the different hydrological regimes in the two streams.

Several diatom species are common to both streams but two, in particular, stand out as being common in Croasdale Beck but rare in the River Ehen.  These are Achnanthes oblongella (illustrated in “Why do you look for the living amongst the dead?”) and Odontidium mesodon.  However, a closer look at the data showed that, whilst both were common in Croasdale Beck, they were rarely both common in the same sample.   If Achnanthes oblongella was abundant, then Odontidium mesodon was rare and vice versa, as the left hand graph below shows.   There were also a few situations when neither was abundant.

Odontidium mesodon from Croasdale Beck, Cumbria, July 2015.  Photographs by Lydia King.

The story got more interesting when I plotted the relative proportions of these two taxa against the amount of chlorophyll that we measured on the stones at the time of sample collection (see right hand graph below).   This gives us an idea of the total biomass of algae present at the site (which, in this particular case, are dominated by diatoms).   Achnanthes oblongella was most abundant when the biomass was very low, whilst Odontidium mesodon peaked at a slightly higher biomass, but proportions of both dropped off when the biomass was high.   I should point out that “high” in the context of Croasdale Beck is relatively low by the standards of other streams that we have examined and this adds another layer of complexity to the story.

When the biomass exceeds two micrograms per square centimetre, both Odontidium mesodon and Achnanthes oblongella are uncommon in the biomass, and the most abundant diatoms are Achnanthidum minutissimum, Fragilaria gracilis or, on one occasion, Cocconeis placentula.   A. minutissimum and F. gracilis are both common in the nearby River Ehen but C. placentula is very rarely found there.

The difference between River Ehen and Croasdale Beck is probably largely a result of the very difernt hydrological regimes, though this is an aspect of the ecology of diatoms that has been studied relatively rarely.   The differences within my Croasdale Beck samples is probably also a result of the hydrology, but reflects changes over time.   I suspect that Achnanthes oblongella is the natural “pioneer” species of soft-water, hydrologically-dynamic streams, and that Diatoma mesodon is able to over-grow A. oblongella when the biomass on stones increases due to prolonged periods of relative stability in the stream bed.  That still does not explain what happens when biomass is high and neither are abundant: the dataset is still small and we need to collect some more data to try to understand this. But the point of the post is mostly to remind everyone of the dangers of trying to interpret the ecology of attached stream algae solely in terms of their chemical environment.   And to make the point that a little more understanding of a natural system often fuels, rather than removes, the sense of mystery that is always present in nature.

a. The relationship between representation of Achnanthes oblongella and Odontidium mesodon in samples from Croasdale Beck between May 2015 and January 2017. Both axes are presented on square-root-transformed scales; b. relationship between representation of Achnanthes oblongella and Odontium mesodon and total epilithic biomass (as chlorophyll a). Lines show a locally-weighted polynomial (LOESS) regression fitted to the data.

Taxonomic note

Odontidium mesodon is the correct name for Diatoma mesodon (see “Diatoms from the Valley of Flowers”).   The name Odontidium had fallen out of popular usage, but Ingrid Jüttner and colleagues made the case to resurrect this genus for a few species that would hitherto have been classified in Diatoma.

Achnanthes oblongella, by contrast, is definitely not the correct name for this organism.  Three other names have been proposed: Karayevia oblongella, Psammothidium oblongella and Platessa oblongella.  The first two are not convincing and I have not yet been able to see the paper describing the third.  It will be interesting to see what a combined morphological and genetic study of this species (or, more likely, complex) reveals.

Reference

Jüttner, I., Williams, D.M., Levkov, Z., Falasco, E., Battegazzore, M., Cantonati, M., Van de Vijver, B., Angele, C. & Ector, L. (2015).  Reinvestigation of the type material for Odontidium hyemale (Roth) Kützing and related species, with description of four new species in the genus Odontidium (Fragilariaceae, Bacillariophyta).  Phytotaxa 234: 1-36.

Wetzel, C.E., Lange-Bertalot, H. & Ector, L. (2017): Type analysis of Achnanthes oblongella Østrup and resurrection of Achnanthes saxonica Krasske (Bacillariophyta). Nova Hedwigia Beiheft (in press).

 

Theme and variations

Following our visit to the cities of the Silk Road (see “Daniel and his den of diatoms …”) in April we turned our eyes in the opposite direction and, within an hour of leaving Tashkent, we had left the flat plains behind and climbing into the foothills of the Tien’shan mountains.   The intensive agriculture of the lowlands gave way to pine forests and, as the road started to twist and turn up the slopes, we started to get tantalising glimpses of the snow-capped mountains which straddle Uzbekistan’s eastern border with Krygyzstan.

As ever, I looked for opportunities to combine business and pleasure, collecting one sample from a small calcareous seepage in the hills near the village of So’qoq and another from a stream running through mixed geology near the village of Kumyshkang, where we were staying in a Soviet-era dacha.   Sampling the seepage drew some curious looks from two women who were collecting water mint from further downstream, and yielded an almost pure growth of a diatom that is either Achnanthidium pyrenaicum or a close relative.   This would have been, by the way, the diatom that I would have expected to find were I to sample a remote, unpolluted calcareous stream in the UK.

Achnanthidium cf pyrenaicum from a calcareous stream near So’qoq in eastern Uzbekistan (41°18’45.6” N 69 ° 51’40” E).  a. – d.: rapheless valves; e. – g.: raphe valves; h.: girdle view.  Scale bar: 10 micrometres (= 1/100th of a millimetre).

Later in the day, we explored a side valley of an unnamed river that flows through the village of Kumyshkang.  The steep landscape on the south side of the valley had a thin cover of scrubby vegetation (in contrast to the wooded slopes on the other side) and the stream tumbled off the hillside towards the river below.  The biofilm, partly as a result of this harsh environment and partly, I suspect, due to grazing by invertebrates, was very thin but, nonetheless, quite diverse, with Achnanthidium minutissimum predominating.  There were a lot of outcrops of pink granite in the hillsides around the stream, but there were other rocks too, including shales and slates.   The flora here, as a So’qoq, would not look out of place in samples I find in the UK although the mix of taxa is not what I would expect if granite was the predominant rock in the catchment.   I travel light, without meters to check the chemical composition of the water, so there is no way to confirm this.  Except by going back one day better prepared …

Diatoms from a stream near Kumyshkang, Uzbekistan (41°18’45.6” N 69 ° 51’40” E, approx. 1400 m above sea level).  .   i.: Ulnaria ulna; j. – l.: Achnanthidium minutissimum; m.: A. cf. pyrenaicum; n., o.: A. cf caledonicum; p.: Achnanthidium girdle view; q.: Navicula tripunctata; r. Navicula sp.; s. Gomphonema gracile; t. Gomphonema sp.; u. Surirella brebissonii var. kutzingii; v. Diatoma moniliformis; w. Nitzschia sp.; x. Planothidium lanceolatum; y. Reimeria sinuata; z.: Encyonema ventricosum; aa.: Encyonopsis sp.   Scale bar 10 micrometres (= 100th of a millimetre).

I should add a caution about names applied to Asian diatoms using identification literature written for European freshwaters, especially after my comments in “Back to the Himalayas …”.   Until the 1980s there was a widespread belief that diatom species were cosmopolitan and could be found all around the world.  This belief became self-fulfilling as, armed with this assumption, biologists set out with books written by and for Europeans and blithely applied the names to the diatoms that they found.  From the 1980s, however, papers started to appear in which people took a closer look at variation in some of these apparently cosmopolitan species and argued that there were, in fact, substantial differences between forms from different locations, and that there were, in fact, much greater numbers of diatoms than previously thought, and that many of these were restricted to particular geographic regions.   But then, in 2002 Bland Finlay and colleagues challenged this emerging view by arguing that it was not diatoms that were restricted in their distributions, it was the locations where these detailed studies had been performed that were rare.   In other words, given enough time and effort on the part of diatomists, we should expect to see these so-called endemic species cropping up in samples from all over the world.

This created a brouhaha within the diatom world which resulted in some further papers that questioned Finlay’s assertions and argued from theoretical grounds that there was no reason why diatoms should not be restricted to a limited geographical area.  As the new century progressed, diatomists added molecular barcoding to their armouries and this offered partial support for both positions: some diatoms – or at least some strains of some diatoms, Nitzschia palea and Gomphonema parvulum, for example – do appear to be genuinely cosmopolitan whilst others do not.  Of course, Finlay and colleagues always hold the trump card in this respect: it is not possible to disprove the existence of any so-called endemic species elsewhere in the biosphere until every conceivable habitat has been examined. But a truce, of sorts, does seem to be emerging.

Sampling the calcareous seepage near So’qoq, April 2017.  The picture at the top of the post shows the valley upstream of Kumyshkang.

The truth may well lie between the two extreme positions.  Maybe many diatoms really are widely distributed because random dispersal mechanisms for microscopic organisms are highly effective, as Finlay and colleagues argue.  But every time a few viable cells of a diatom species land on a suitable habitat, their small pool of genetic variability will either thrive or disappear.   When they thrive, the story of Darwin’s finches will be replayed and a combination of genetic drift and selective pressures will create variations on the original theme, just waiting for an observant biologist to come along and discover the new species.

The question that intrigues me is whether or not the bugs that crawl across the submerged stones in search of food ever notice the difference.   One of my perennial bugbears is that the careful taxonomic work that has resulted in the discovery of all this diversity within diatoms is rarely accompanied by ecological analyses of similar rigour.   In particular, do these different forms of what we once regarded as “cosmopolitan” species actually have any effect on how energy flows through the ecosystem?  Do they, in other words, taste different to the invertebrates that crawl across the stones in search of food?  Or, as Bland Finlay hinted in a subsequent review article, are these different genotypes, in effect, variations on the same basic “ecotype”?   In which case, a casual observer crouching beside a foreign stream may not know the precise name of every species he encounters but still may have a pretty good idea of how these fit into the bigger picture of aquatic diversity.

References

Finlay, B.J. (2002). Global Dispersal of Free-Living Microbial Eukaryote Species.  Science (New York) 296: 1061-1063.

Finlay, B.J. (2004). Protist taxonomy: an ecological perspective.  Philosophical Transactions of the Royal Society Series B 359: 599-610.

Finlay, B.J., Monaghan, E.B. & Maberly, S.C. (2002). Hypothesis: the rate and scale of dispersal of freshwater diatom species is a function of their global abundance. Protist 153: 261-273.

Kemmarec, L., Bouchez, A., Rimet, F. & Humbert, J.-F. (2013). First evidence of the Existence of Semi-Cryptic Species and of a phylogeographic structure in the Gomphonema parvulum (Kützing) Kützing complex (Bacillariophyta). Protist 164: 686-705.

Mann, D.G. & Droop, S.J.M. (1996).  Biodiversity, biogeography and conservation of diatoms.  Hydrobiologia 336: 19-32.

Telford, R.J., Vandvik, V. & Birks, H.J.B. (2006). Dispersal limitations matter for microbial morphospecies. Science (New York) 312: 1015.

Trobajo, R., Clavero, E., Chepurnov, V.A., Sabbe, K., Mann, D.G., Ishihara, S. & Cox, E.J. (2009). Morphological, genetic and mating diversity within the widespread bioindicator Nitzschia palea (Bacillariophyceae). Phycologia 48: 443-459

Vyverman, W., Verleyen, E., Sabbe, K., Vanhoutte, K., Sterken, M., Hodgson, D.A., Mann, D.G., Juggins, S., van de Vijver, B., Jones, V., Flower, R., Roberts, D., Chepurnov, V., Kilroy, C., Vanormelingen, P. & de Wever, A. (2002). Historical processes constrain patterns in global diatom diversity. Ecology 88: 1924-1931.

A view of the Tien’shan mountains from near So’qoq, Uzbekistan.

How green is my party?

It seems like only a short time ago that I was considering the manifestos for the 2015 General Election (see “The political landscape isn’t very green …”).   And it seems like a lifetime ago, such are the potential ramifications of the Brexit vote (see “What has the EU ever done for us?”).   So what are the main parties saying about the environment in their manifestos this time around?

First impressions are important and, looking at the contents pages, I see that neither of the two largest parties regard the environment as sufficiently important to merit a chapter to itself.  There are crumbs of comfort tucked away in the text of both: both, for example, commit to improve natural flood management and to take a lead in global action against climate change.  Labour go a little further than the Tories with an explicit commitment to replace the Great Repeal Bill with an EU Rights and Protections Bill which should guarantee environmental standards.   Both manifestos, however, make some bizarre claims: the Tories will create a “Shale Environmental Regulator” when the best way to manage shale gas extraction (if this were to be allowed) would be to strengthen the current regulator’s powers.  Labour’s plan to take utilities (including water) back into public ownership also makes little sense from an environmental perspective.  Indeed, by making utility bills into a political issue, it may even become harder for regulators to argue for price rises to pay for the capital investment necessary to improve water and environmental quality.  Neither manifesto addresses the important questions raised by Caroline Lucas and others (see “(In)Competent Authority?”) about who will watch the watchmen once the oversight of the European Court of Justice is removed.

What of the other parties? UKIP come straight out with a commitment to repeal the Water Framework Directive, claiming that it led to serious flooding in many parts of the country by preventing river dredging.  Curiously, given that this statement is tenuous, to say the least, their next sentence promises that UKIP will promote “evidence-based environmental schemes”.   Given the current state of Environment Agency finances, I hope that this claim is supported by plenty of cash, otherwise the evidence needed to promote strong environmental regulation will not be available.  Or maybe that’s the point?   Flick to the end of their manifesto and look at the fiscal plan: no explicit mention of the environment and only a meagre sum allocated to “provision for other policy items”.   I think we can move on …

The other two national parties give the environment more prominence.  The Liberal Democrats devote a whole chapter to “Keep our Country Green” and maintaining EU environmental standards is part of their case for fighting a hard Brexit.   Like the Tories and Labour, they commit to encouraging natural flood management; unlike the larger parties, they put a cash sum (£2 billion) against this pledge in the body of the manifesto.   Apart from this, the Lib Dems make few specific claims for how the aquatic environment will be managed; however, there is a much wider range of green measures in their manifesto than either of the two main parties can manage.

The Green Party also follow the trend for natural flood management and promise to put environmental protection at the heart of any future trade deals.  However, there is less detail in this manifesto than there was in their 2015 manifesto and, in particular, only a single reference to farming.   Even the most ardent EU supporters find it hard to mourn the end of the Common Agricultural Policy, and the Greens are not the only ones who realise that there is an opportunity here to build a greater emphasis on countryside stewardship into the system that replaces the CAP.

Despite this, the Green Party have the most visionary outlook of all the major political parties.  Labour and the Conservatives are still wedded to GDP growth, with the environment as a subsidiary issue but the Greens have a more holistic world view that challenges traditional economics.   I have just read Kate Raworth’s Doughnut Economics (Random House, 2017), which explores the possibility of alternative, more inclusive, healthier approaches to economic management.  The Greens get this, pointing out that “consumer capitalism is the problem, not the solution.”   That, however, is their greatest weakness as well as their strength: electoral success for them will depend upon those consumer capitalists being satisfied with less despite the larger parties seducing them with offers of greater prosperity.

We should probably look beyond specific references to the environment in order to divine the prospects for our water and countryside.   The Brexit negotiations will be key yet the manifestos can only capture the ambition of one half of the negotiation process.   What exactly does the Tory desire for a “deep and special partnership with the EU, which will allow free trade between the UK and the EU’s member states” mean?   It could mean a willingness to accept EU employment and environmental standards to ensure a level-playing field for trade.  But Theresa May has to keep a wary eye on the belligerent right-wing of the Tory party who will see such standards as “red tape” that should be sacrificed rather than compromise with the hateful Brussels bureaucracy.

Overall, I think that Theresa May and the Tories will bring too much ideological baggage to the negotiating table to allow a truly constructive partnership with the EU to emerge.   The narrow vote in last June’s referendum would justify a “soft” Brexit, for which the other parties will be better placed to negotiate.   The Lib Dems and the Greens both promise a second referendum to confirm the terms of UK’s leaving, which is a reasonable aspiration with the sole drawback that the electorate are already jaded and unlikely to have any enthusiasm to be dragged to the polling stations yet again.   Overall, given the lacklustre approach to the environment from both the main parties, perhaps our best hope on June 8 is another coalition?   If that includes the Green Party then maybe an awareness of the importance of sustainability and the environment will start to be embedded throughout Government policy instead of being quietly relegated to the margins.