An Indian summer on our riverbanks …

One of my favourite places in County Durham is, paradoxically, also one of the most polluted.   When I first visited, over thirty years ago, the stretch of the River Team pictured below was heavily polluted from several sources, including sewage works, abandoned coal mines and a large battery factory, just a couple of kilometres upstream. The latter made the river an ideal open-air laboratory for work that we were doing at the time on the effect of heavy metals.   The River Team, like many other rivers in this part of County Durham, flowed through a gorge incised into the landscape. The steep slopes of the gorge made agriculture and settlement impractical so locations such as this are blessed by beautiful wooded valleys (the incised meander at Durham City is the most famous example of these – see “The River Wear in summer”).

Causey_Arch_July2014

Causey Arch crossing the River Team in County Durham, July 2014.

Causey Arch, the bridge in my picture dates from 1726 and is the oldest surviving single-arched railway bridge in the world and is a reminder of the region’s industrial heritage. George Stephenson is a local lad and the Stockton and Darlington Railway, the first public railway to use steam locomotives, is just 50 km to the south. So do not be deceived by the idyllic view of the wooded gorge around Causey Arch: the surrounding area has a high population density and a long history of water-polluting industries.

Although the battery factory that polluted the river in the 1970s and 80s has now closed, the river is still heavily polluted, particularly from a sewage works about a kilometre upstream from where this photograph was taken.   There has, however, been one other change since my first visits in the early 1980s: the banks of the river are now thick with the pink-flowered plants of Himalayan Balsam, Impatiens glandulifera.   The riverbanks do not just look different, they are also heavy with Himalayan Balsam’s sweet, pungent odour.  Ironically, these changes have taken place as the water quality itself has gradually improved.

As the name suggests, Himalayan balsam is not a native plant; it was introduced here in the 19th century for its attractive pink flowers but has escaped from gardens to become a nuisance over much of the country.   You can read more about this in Heather’s blog, written in preparation for her trip to the Himalayas later this year.   She refers back to Frank Smythe’s classic book “Valley of Flowers” in which he notes that, even in the Himalayas, this plant is often a nuisance weed.

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Himalayan balsam, Impatiens glandulifera, growing at Causey Arch, County Durham, July 2014.

My own private gripe with Himalayan balsam is that the tall plants grow just far enough apart to allow nettles to thrive in the gaps. I’ve struggled to get into rivers to collect my samples several times this year already and suffered multiple stings as a result.   I have slowly realised that my chest waders, though very hot to wear on a sunny day, are much preferable to bare legs.

Postscript

There is more about invasive plants in the Plant Invaders episode of Plants: from Roots to Riches on the BBC iPlayer. Curiously, Himalayan balsam is not mentioned in this programme but it is worth a listen nonetheless.

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A journey down Memory Lane

On the way back from Latitude I called in to see my daughter’s new flat in Lincoln and realised that it was just a couple of hundred metres from a rather ghastly 1970s monstrosity of a building that played a small but significant role in my professional life.   In its current guise Aqua House, Lincoln is occupied by Anglian Water but back in 1991 it was the local office of the National Rivers Authority (NRA), the predecessor to the Environment Agency.

I had just returned from two years teaching at a university in Nigeria to take up a National Rivers Authority fellowship at the University of Durham.   During my time in Nigeria, I had known several development professionals and they were always emphasising the importance of consulting the beneficiaries in order to tailor aid and development programmes to their needs rather than imposing well-meaning “solutions” conceived by “experts”.   The key phrase was “bottom up”; “top down” was virtually an insult.

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Aqua House, Lincoln. The River Witham is on the right hand side of the picture.

Having been tasked for my fellowship with developing new approaches to assessing ecological quality, it made perfect sense for me to go on the road and talk to some experienced NRA biologists to get their views on what was needed.   I visited Nottingham and Lincoln on this trip, along with a couple of other laboratories on other visits. At Lincoln, I met Chris Extence and Bill Brierley and we had a lively chat for an hour or so.   The message that came out loud and clear from them, as well as from several of the other biologists I spoke with, was that, in RIVPACS, the NRA had an effective means of assessing organic pollution. There would be no point in trying to re-invent the wheel and develop an algal-based method that could do this.   However, they did comment on the inability of RIVPACS to detect the effects of inorganic nutrients.   Several had noticed, in the course of their visits to rivers to collect invertebrate samples, a gradual increase in the quantities of filamentous algae that they were seeing.   A means of quantifying this would let them make more systematic observations that would complement, rather than overlap with, data from RIVPACS.   That in turn, set me thinking and led, eventually, to the development of the Trophic Diatom Index.

I do remember that these road trips to consult biologists at the sharp end of environmental regulation were tolerated rather than encouraged by my supervisor at the time.   His attitude was that we should tell the NRA what they needed rather than ask what was wanted.   It was an attitude typical of academics of the day and, I am afraid to say, still very common.   Until just a few years ago, biologists who worked for the NRA, the Environment Agency and similar bodies spent far more time in the field than the average mid-career academic and had a tremendous amount of knowledge about their local rivers as well as an understanding of the broader legislative framework that is necessary if you are to convert “data” into “evidence” that can be used to drive improvements.  I am fairly sure that, without those trips to Lincoln and other NRA offices back in 1991, I would have spent the next two years tilting at windmills.

Thinking laterally at Latitude 2014

One of my personal challenges when I am teaching is to help students see new discoveries and advances from the perspectives of people living at the time.   I spend part of my course explaining the development of public health understanding in the mid nineteenth century as a means of setting the scene for describing our modern approach to water pollution.   I do this by using, as my starting point, the closest analogue most of them have to life in a Dickensian city: the music festival, with basic sanitation and no running water (see “I wish I was at Glastonbury”)

I used the opportunity of a day ticket to the Latitude festival last weekend to update my visual aids for my lecture which means, I guess, that my visit to the festival counts as “work” and, therefore, that the entire day is now tax-deductible?   Or am I starting to think like an MP?

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Latitude’s loos, 2014.   Updated visual aids for my Aquatic Pollution course at Newcastle University.

To be fair to Latitude, their loos were amongst the finest I’ve ever encountered at a music festival, so perhaps this was not the full Victorian experience that I want my students to imagine.   But we don’t need to tell the taxman that, do we?

My trip to Latitude was partly to let my mother, a 75-year old Professional Grandmother experience these festivals that her children and grandchildren had been telling her about.   Fortunately, the gods smiled on us, giving us a warm, sunny day to experience music, poetry and dance, as well as to sit in the sunshine eating al fresco from one of the many stalls.   One of my memories will be the sound of an Indian dance troupe’s instruments fading away to be replaced by the chugging organ riff of Booker T’s Green Onions rolling across the lake from the Obelisk stage.   A few minutes later, Booker T struck up Soul Limbo, the Test Match Special theme tune.  A hundred miles away, England were battling to survive the second test against India at Lords but in Suffolk we all had smiles on our faces.   That, in turn, reminds me of Glastonbury in 2010 (see “An England fan in Vilnius”)

Latitude_2014

Latitude 2014: First Aid Kit on the Obelisk stage; my mother enjoying her first festival at 75.

One musical highlight for me was First Aid Kit on the Obelisk stage, whose folk-rock harmonies were a perfect soundtrack to a summer’s evening. But let’s get the obvious comparison out of the way: Swedish: tick; two pretty girls: tick; one blonde, one brunette: tick, but that’s where the resemblance to Abba ends, whatever some of those standing near me were saying.   I can’t go for that. No can do.

 

 

Another name for the pearl mussel hall of shame

Legendary wildlife cameraman Doug Allan appeared on BBC Radio 4’s Desert Island Discs this week and cheerfully described his first job after graduating, which involved diving in Scottish rivers in search of pearl mussels. Having already described food writer Nigel Slater’s brush with wildlife crime (see “Pearl mussels and porridge”), I would encourage you to go to the BBC website and listen to the programme if only because of Allan’s vivid description of harvesting and selling pearl mussels in the 1970s.   Wildlife legislation was different then, so the word “crime” is clearly not appropriate. Attitudes have changed, too, though we’ve all heard that defence too often in the various trials associated with Operation Yewtree to feel comfortable.

You’ll also have to listen to Doug Allan’s choice of eight records to take to a desert island. The man redeems himself by making Bruce Springsteen’s Thunder Road his first choice.

Every second breath …

“I am determined”, said Kathy Willis of the Royal Botanic Gardens at Kew in an interview in The Independent on Monday, “to prove botany is not the ‘Cinderella of science’”. How does she plan to do this?   Her platform for this bold endeavour is a new series for Radio 4 entitled “Plants: from Roots to Riches”.   It starts next week and there will be 25 episodes, airing daily just after the World at One.   A quick look at the series website was enough to convince me that this series will not present botany as the ‘Cinderella of science’. Ugly Sister, maybe, but certainly not Cinderella.

Okay: I write a blog about the unfashionable end of biodiversity so you should probably have a rough idea of where this is all heading.   I went to the program website where the subjects for the first two week’s episodes are listed.   I saw one episode on fungi and one on cycads, which are a group of Gymnosperms but otherwise there is a very strong bias towards the flowering plants, the brash, over-dressed near relatives of the algae who, in my version of the pantomime that is natural history broadcasting, are ideally cast for the role of ‘Cinderella’.

Does it matter? It is flowering plants, after all, which provide us with most of our carbohydrate intake, many fibres and pharmaceuticals and clothe our landscapes in myriad different ways. Why should we concern ourselves with a group of organisms that most of us never notice?

Try this exercise: breathe in, breathe out. Don’t breathe in. Hold your breath. Now breathe in again.   And out. Hold your breath again.   Repeat. Keep repeating. Keep skipping every other breath.

That’s why I am bothered.

Half of all the energy that is trapped by the sun and converted to energy comes from algae. In the course of photosynthesis plants and algae produce oxygen. It replaces the oxygen that plants and animals – including us – suck out of the air for our own survival.   Algae, indeed, put a lot of that oxygen into the atmosphere in the first place (see “Every (fifth) breath you take …”). They also represent a large part of our planet’s biodiversity (see “The sum of things …”).   I am forever worried when algae get side-lined in favour of the more visually spectacular elements of the plant and animal worlds though I don’t have an easy solution.

This is not a moan directed at Kathy Willis in particular. Indeed, she is in good company as David Attenborough, too, is a serial offender.   My problem is a broader one about how we can overcome the inevitable bias in natural history programming.   I have been writing a blog about algae for 18 months now. I know the problems. These organisms are not anthropomorphic, they have no courtship rituals, their sex life makes pandas appear horny (see “The perplexing case of the celibate alga” amongst other posts) and their offspring do not have big, yearning eyes.   People usually notice algae only when human activities have disrupted the balance so the algae become a problem. It is hard to convince people of the important role that algae play in the natural world. That’s why I suggest that it is algae that deserve the title of “Cinderella of Science”.   Just remember: every second breath …

Of course, I may be too hard on Kathy Willis. We can only see the first two week’s programs on the website at the moment. Maybe … just maybe … she’s leaving the best until last.

Reference

Kirchman, D.L. (2012). Processes in Microbial Ecology. Oxford University Press.

Rewriting history at Talkin Tarn …

One of the joys of modern technology is the ability to right obvious wrongs.   So, having watched my wife’s crew struggle in a regatta at Talkin Tarn, near Brampton, last weekend, having been entered in the wrong class and the wrong age category and then racing in a men’s rather than a woman’s boat, I had no option but to turn to Photoshop for justice.   Here, in a rewritten version of the Talkin Tarn regatta, you can see the DARC novice women’s coxed four half a length head of their opposition with about 400 metres to go.   The backdrop is the Pennine fells, looking north towards Hadrian’s Wall.

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Talkin Tarn regatta 2014: DARC novice women’s coxed four half a length ahead of the opposition.  

I have to confess that the entertainment value of watching one crew busting a gut to go slightly faster than another crew pales after the first hour, so I wandered off to poke around the lake’s margins.   The water here contained some just discernable green specks, all between about half a millimetre and a millimetre across.   Under the microscope, these resolve into spherical colonies each composed of filaments which gradually taper from the base.   These colonies belong to a cyanobacterium (blue-green alga) called Gloeotrichia echinulata. I’ve written about relatives of Gloeotrichia in previous posts (“Blue skies and blue flowers in Upper Teesdale”, “”Looking” is not the same as “seeing” …”, “More about Rivularia”) and have commented that the large light coloured cells, called “heterocysts” are responsible for nitrogen fixation, which enables the alga to grow even when nitrogen is relatively scarce. In the case of Talkin Tarn, the scarcity is probably not absolute but relative to other nutrients such as phosphorus. It means that the Gloeotrichia can grow even when the supply of this important nutrient has run out.

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Colonies of Gloeotrichia echinulata in a drop of water from Talkin Tarn, July 2014.   The drop is 12 millimetres across.

One other difference between the filaments of Gloeotrichia and those of Rivularia is the dark specks inside the cells.   These are gas vacuoles which make the cells and colonies of Gloeotrichia more buoyant than other algae. Leave a sample from Talkin Tarn to stand for a while and the colonies of Gloeotrichia will rise to the surface. This gives cyanobacteria a competitive advantage over other algae in lakes as they now have an adaptation that keeps them closer to the sunlight which powers their photosynthesis as well as one that helps them to overcome nitrogen limitation and an adaptation.   It is no surprise that cyanobacteria are so prolific in lakes around the world.

Gloeotrichia_echinulata_tal

Microscopic views of a Gloeotrichia echinulata colony from Talkin Tarn.   The left hand image shows an entire colony, about half a millimetre across.   The right hand image shows the same colony at higher magnification.   Note the large, round light-coloured heterocysts at the base of each filament. Scale bar: 10 micrometres (= 1/100th of a millimetre).

Gloeotrichia also has the ability to produce compounds called “microcystins” which are powerful toxins.   There are many records of livestock, dogs and humans suffering liver damage through ingesting contaminated water.   Although the rowers at Talkin Tarn were warned to wash their hands after racing, the risk is only high if a large amount of Gloeotrichia-containing water is swallowed. That is unlikely in a sport such as rowing, where the idea is to stay in the boat, but swimming in Talkin Tarn would not be a good idea. Rowing, though, is not without such dangers: the Durham women’s novice crew’s previous opponents suffered an “ejector crab” at the start which dumped one of them into the River Wear. On that occasion, cyanobacteria in the River Wear were the least of their worries and the Durham crew were able to cruise serenely down the river to a glorious victory.   Photoshop not required.

 

More about Oedogonium

Having written about a population of Oedogonium that I found in an enriched lowland stream a couple of weeks ago (see “The perplexing case of the celibate alga”), I arrived at the River Ehen last week to find much of the stream bed covered with a dense growth of filamentous green algae that, once again, turned out to be composed largely of Oedogonium.   This soft water site differs in many ways from Stockerley Burn, but a species of Oedogonium seems to be thriving here too. Looking back at my notes, I see that I also found it at the same location this time last year.   The quantities are such that colleagues are concerned for the health of the pearl mussels which also grow here (see “Pearl mussels in the River Ehen”).

Oedogonium_wefts_Ehen_Jul14

Wefts of filamentous algae (mostly Oedogonium) on the bed of the River Ehen, July 2014. Note, too, the flocculant material on the surfaces of the boulders.

The photomicrographs of Oedogonium also show very nicely the reticulate (net-like) nature of the chloroplast.   You can also see two cells of the diatom Tabellaria growing epiphytically on the lower filament.

Oedogonium_Ehen_stack

Photomicrographs of Oedogonium from the River Ehen, July 2014.   Note the cap cells (arrowed) and the reticulate (net-like) chloroplasts.   Scale bar: 25 micrometres (1/40th of a millimetre).

We do not yet have a definitive explanation for the proliferation of Oedogonium in the River Ehen.   The most likely explanation is that the river levels have been low for some time and this means that the gradual accumulation of algae proceeds without the sloughing that occurs when the river is in spate.   The longer the algae can grow without disturbance, the higher the biomass.   When there is a spate and stones are rolled over, the algae that were on top of the stone are deprived of light and gradually die and decompose.   This means that the space between the stones of the substrate, through which oxygen-rich water flows to sustain the young pearl mussels becomes a fetid aquatic “compost heap” which will, in turn, extract this oxygen and make life for the young pearl mussels more difficult. As this is the last healthy pearl mussel population in England, my colleagues in conservation bodies are probably the only people in a region largely dependent on tourists to sustain its economy who are hoping for rain.