Tuesday, December 24, 2013

Downsizing Christmas

I germinated this spruce tree from a seed that was sent to me eight years ago, with the intention of growing it as a bonsai specimen. This year it's finally big enough to cope with some Christmas decorations. If I'd planted it in the garden it might eventually have grown to about 50 feet tall; as a bonsai it's unlikely to grow to much more than a couple of feet, but it'll be a family Christmas tree that I can hand on to my children. Once Christmas is over it will get some careful  pruning and training.

Best wishes for a Happy Christmas to all who have visited and commented on this blog throughout 2013.

Wednesday, December 18, 2013

Beeching's Legacy

Thursday's Guardian Country Diary describes a walk along a section of disused railway line between Romaldkirk and Cotherstone in Teesdale, which now forms part of the Tees Valley Railway Path.

When I was a kid I went to school on the train every day. I travelled on electric trains but those were still the dying days of steam and I can still recall the sound and the smell of steam locomotives like these thundering through the station while I waited for my sedate electric train to arrive. Along with my mates I often stood on the footbridge while the fire-breathing, steam-snorting monsters passed underneath.

The mainline steam trains are now a distant memory - and so are many of the rural railways that were axed in the Beeching closures in 1963.

This is what the rail network looked like before Beeching ......

...... and this was what remained when he'd finished his work.

But it's an ill wind that blows nobody any good, and many of the old railways lines whose tracks have been lifted are now excellent footpaths that pass through some spectacular countryside and have often become unofficial nature reserves. 

Here are some pictures of some fine local examples:

The Tees Valley Railway Path photographed in high summer this year.

A wonderfully festive hawthorn berry crop along the route this winter ...

..... with plenty of holly - Cotherstone village is in the distance.

This is a cutting along the Tees Valley Railway Path near Romaldkirk earlier this year, in February. Drifting snow that filled railway cuttings often brought trains to a standstill when lines like this in the Pennines were still in use.

The footpath along the old railway line that runs through the nature reserve at Smardale Gill in Ravenstonedale, Cumbria ....

.... where the Smardale Gill viaduct carries the line through the limestone grassland.

This is the same line, but this time on the eastern side of Kirkby Stephen, where the line travelled eastwards across the notorious Stainmore Summit - the highest railway in England.

The line east of Coxhoe in County Durham, with magnesian limestone embankments rich in wild flowers and butterflies.

And finally, the railway path through the Derwent Country Park near Gateshead, where you can walk on the track bed of the old Derwent Valley Railway through woodland to the Nine Arches viaduct and watch red kites soaring overhead.

Saturday, December 14, 2013

More bathroom biodiversity: the Celibate Rotifer

A few days ago I posted some pictures of tiny animals called tardigrades that I found living in the wet mould growing on our bathroom window. 

They weren't the only wildlife that I found there; when I looked at two more pinhead-sized samples of the mould under the microscope theycontained several of these bdelloid rotifers. These are about a quarter of a millimeter long and are truly extraordinary animals.

Bdelloid rotifers consist of an elogated body containing complex internal organs. Normally they are anchored by their tail and when at rest they extend a pair of organs on their head that form the corona, each with a circle of cilia. The  cilia are anchored but because they beat rhythmically it appears as though they rotate - which is why the paired structures are sometimes known as wheel organs. 

The beating cilia create a vortex in the water that draws small food particles into the rotifer's mouth - click here to view a couple of movies which illustrate this far better than words can.

One peculiarity of bdelloid rotifers that intrigues biologists is that they never undergo sexual reproduction; they reproduce clonally and have done so for around 80 million years. 

It's generally assumed that sexual reproduction evolved because it generates offspring that are genetically different from their parents, which is beneficial in a constantly changing environment; somewhere amongst the genetically variable population there are always likely to be some that are better equipped than others to deal with new challenges, like changing climate or new diseases. 

Clonally reproducing organisms, like these rotifers, are all genetically identical so they should all be equally susceptible to change or disease and would be prone to extinction. So how have these rotifer clones managed to survive after 80 million years of celibacy?

The answer seems to be that they can incorporate DNA from their food - which consists of fungi, algae and bacteria - into their own DNA, so generating genetic variation in their population. Like tardigrades they are very drought-resistant and when their surroundings dry out they form a tough, durable cyst. 

When the cysts hatch again and rehydrate breaks develop in their DNA molecules that would normally be fatal, but DNA from their partially-digested food is used to repair these, so about eight per cent of rotifer DNA actually comes from fungi, bacteria and algae. It gives new meaning to the old  saying "you are what you eat".

You can see partially-digested food (most likely mould from our bathroom window) inside this rotifer's gut.

Rotifers like this are ubiquitous. Their durable eggs are transported by water and wind and they hatch anywhere that is moist. Mosses are habitats where you can find them in very  large numbers. If you keep cut flowers in a vase you can almost guarantee that there will be a large population of rotifers living on the submerged stems within a week. 

This is a higher magnification image that shows the corona, where you can just make out those beating hairs ....

 ..... and these are the jaws (the mastax) in the neck of the animal. They chew constantly. Here they are open ....

.... and here they are closed.

There's one other amazing property of rotifers that sets them apart - they are more resistant to radiation than any other animal. Tests have shown that they can survive doses of radiation that are 100 times greater than would kill a human, which means that when there are nuclear reactor accidents these will be last animals to succumb. This again is probably due to the unusual ease with which they can repair breaks in their DNA.

It's amazing what you can find in your bathroom. I wonder what's lurking behind the sink................

For pictures and information about some more rotifers, click here.


Gladyshev, E.A., Meselson, M., Arkhipova, I.R. (2008). Massive Horizontal Gene Transfer in Bdelloid Rotifers. Science, 320, 5880

Gladyshev, E., Meselson, M. (2008). Extreme resistance of bdelloid rotifers to ionizing radiation. Proceedings of the National Academy of Sciences 105 (13), 5139-5144

Jean-Francois Flot et al (2013) Genomic evidence for ameiotic evolution in the bdelloid rotifer Adineta vaga. Nature 500, 453–457

Wednesday, December 11, 2013

A bit of a stink

Few of our native wild flowers have such beautiful fruits, but such an unpleasant name, as stinking iris Iris foetidissima. I grew some plants from seed a few years ago and planted them in dry sandy, sun-baked soil under our garden hedge, where they've thrived ever since and produce these lovely seed capsules that open in late November to reveal their spectacular seeds.

Two other common names, gladdon and roast beef plant are also in common usage and the latter refers to the smell of the crushed leaves that have a powerful aroma of beef (though to me they smell more of roast beef-flavoured crisps, rather than the real meat). In The Englishman's Flora Geoffrey Grigson listed no less than seventeen further common local names used in various parts of the British Isles. A proliferation of such names for a plant is usually a sign that people once found it useful and gladdon has a long history of applications in herbal medicine, mentioned by Dioscorides, William Turner and John Gerard in their herbals. One popular use was as a purgative, made from a decoction of gladdon root and beer.

In his Botanical Arrangement the 18th. century doctor and botanist William Withering, always a good source of contemporary anecdotes, mentions that "the juice of the root of this species is sometimes used to excite sneezing; but it is an unsafe practice, violent convulsions sometimes having been the consequence."

I rather like the flowers that are unspectacular and reminiscent of faded denim, but Withering wasn't so impressed, describing them as being "of a disagreeable purplish ash colour", also mentioning that in his day there was also a variegated-leaved form which now seems to have disappeared from cultivation.

Saturday, December 7, 2013

Biodiversity in the Bathroom

There can't be a bathroom in Britain where steam doesn't sometimes condense on cold windows at this time of year - and wherever moisture accumulates around window frames bathroom mould is sure to grow, unless you dry the windows very thoroughly every morning. 

So while I was laying in the bath yesterday I wondered what the mould looked like that I could see was beginning to grow in the corner of the uPVC window frame, and today I scraped a tiny amount off - about enough to cover the head of a pin - and had a look at it under the microscope at x 40 and x100 magnification. 

The fungal hyphae were pretty uninteresting but the animal life that was living amongst them was fascinating, and included three of these ....

..... delightful little tardigrades.

Tardigrades are minute but complex animals that are also known as water bears or, in the US, moss pigs. Most of them live in mosses, stabbing moss cells with mouthparts that resemble aphid stylets and then sucking out the cell contents. 

These three, that were about a fifth of a millimetre long, must have been feeding on the bathroom window mould. If there were three in the tiny sample that I collected, there must be vast numbers on houses where the fungus is allowed to grow unchecked around condensation-soaked window frames.

These are lively little animals with a brain, complex digestive organs and two eyes.... 

.... that you can see in this higher magnification view. The arrow-shaped structure between the eyes is the stylet, used for feeding, with a muscular pharynx at its base.

Tardigrades have eight stubby little legs, each equipped with a pair of claws that are visible on the end of one leg in this image. This makes them particularly adept at clambering through the branches of a forest of mosses - or through the fungal hyphae of bathroom mould. 

You can find a wonderful scanning electron microscope image of a tardigrade by clicking here and a long article in American Scientist on these fascinating animals by clicking here.

So how did they arrive in the bathroom? Almost certainly via their minute eggs which are carried everywhere on the wind. 

These animals are totally harmless but I guess you might find the thought of numerous tardigrades crawling around wet window frames as either fascinating or disgusting; if it's the latter and you are about to rush off and douse your windows in disinfectant, just ponder this. 

When dry conditions prevail, tardigrades survive  by producing drought resistant eggs that are amongst the most indestructible living organisms on the planet. When they are in the egg stage (known as the tun stage) they can survive immersion in boiling water and liquid nitrogen and can survive for decades before they hatch again. Your disinfectant won't have much effect on the eggs, even though it'll kill the adults.

But, most remarkably, these are the only multicellular animals that have ever travelled in outer space without a space suit and survived, when they were flown as tuns in the Space Shuttle - a feat that no human will ever equal. They deserve some respect. For a detailed account of their adventures in outer space, click here and here.

Something I'll ponder when I'm  laying in the bath tonight and watching the condensation trickling down the windowpane.

You can find some more pictures of tardigrades, this time extracted from mosses on our garage roof, by clicking here.

Wednesday, December 4, 2013


Thursday's Guardian Country Diary is about two separate populations of starlings that inhabit the seafront at Whitburn, near Sunderland. One flock, usually of about 100 birds, is often to be found either on the shore amongst the strandline seaweeds at low tide or at high tide feeding on a patch of grassland on low cliffs at the north end of the beach. They exhibit all the 'normal' starling behaviour and are very easily spooked - they spend a lot of time in flight but when they do settle they don't stay grounded for very long - when one bird takes to the air the others always follow.

Further to the south along the seafront this little group, of around a dozen birds, has adopted a completely different life style, forsaking the panicky behaviour of the flock and .....

.... instead spending their time on the promenade, oblivious to cyclists, dog walkers and passers-by and focusing all their attention ....

.... on promenaders who buy fish and chips from the shop across the road and sit and eat them leaning against the sea wall. They're waiting for someone to throw them a chip and they usually beat the resident herring gulls to the prize.

Despite abandoning the collective paranoia of the flock in favour of a life of cadging fast-food, this streetwise splinter group is in fine fettle - life on the streets suits them well - and they are clad in immaculate early winter plumage.

Unlike the flocking birds at the far end of the promenade, this individual was completely fearless, maybe expecting me to throw it a chip in return for a photo-opportunity.

Wednesday, November 20, 2013

The Industrial Revolution in Reverse - Steam gives way to Water Power

Thursday's Guardian Country Diary describes an unusual piece of industrial archaeology in a remote Northumbrian valley.

This is the sight that greets you when you follow the track down from the delightfully-named Pennypie cottage towards Blanchland, at the mining hamlet of Shildon (not to be confused with the town of Shildon in County Durham) which is a mile north of Blanchland. All that's left of this community, that in its heyday numbered over 150 people, is a couple of cottages and this old engine house, together with some mine shafts in the hillside.

The engine house was built in 1806 by mine owner John Skottowe, to house a Boulton and Watt steam engine that was built to pump water from the underground lead mine shafts and tunnels. Waterwheel-driven pumps were no longer up to the job so he imported the latest technology from the tin mines of Cornwall.  A contemporary account describes how 'a steam-engine of great power was erected, the cyclinedr being of 64 inches in diameter, and the main beam weighing upwards of nine tons'.

It should have solved Skottows' problems especially as he owned coal mines across the border in County Durham, but the steam engine turned out to be uneconomic and he reverted to waterwheel driven pumps, dismantling the steam engine and transporting it to Backworth colliery. There was no rail access to Blanchland when the mine engine was installed and even when a rail link did arrived (in 1834) the line ended at Parkhead, five miles away.

The likely reason why steam-driven pumping was abandoned is that this little valley is so remote Even today the roads quickly become treacherous after a snow fall and two centuries ago, when they were less well maintained and horses and carts were used, they must often have been impassible in winter. 

After the steam engine was removed the building was converted to miners' accommodation, with the addition of three floors inside, and it became known locally as 'Shildon Castle'. The mine went into decline, unable to compete with imported lead, and many of the miners emigrated - you can read fascinating accounts of some of them by clicking here

This is the slit in the wall where the beam of the steam engine would have rocked up and down. At the top of the slit you can see the fireplaces that were installed when the building was converted to workers' flats.

You can see more photographs of the site, before its recent restoration, by clicking here

There was a vigorous exchange of mine workers and mining technologies between Cornwall and Northumberland in the early 19th. century, which you can read about by clicking here

You can download a useful pdf guide to the geology and landscape around Blanchland by clicking here

You can download a detailed report on Blanchland and its surround area by clicking here

Sunday, November 17, 2013

The Itinerant Flora of a City

Every year the cityscape of Newcastle changes, as old buildings are demolished and the legacy of polluting industries from the past is cleared away. This site is in the Lower Ouseburn valley, once the location of a devil's caudron of industrial pollution but soon to become the site of 76 energy efficient 'green' homes. 

The patch of land in this picture has been derelict for several years - just a pile of broken bricks and earth bulldozed and then left, so that temporary colonisers took over.

Two years after the land was bulldozed, in the summer of 2011, it hosted the finest display of dyers rocket aka weld Reseda luteola that I've ever seen.

The site was so densely covered with this bee-friendly biennial that I wondered whether it might be the legacy of these plants being used in dye production in the 19th. century; in his New Naturalist book Weeds and Aliens Sir Edward Salisbury suggests that the plant's abundance and distribution often suggests that large populations are relicts of the plants' former cultivation. They have a vast seed output (Salisbury quotes up to 76,000 seeds per plant) and it's possible that the seed could have remained dormant for many decades.

There was also a good display of corn poppies amongst this temporary urban field of wild flowers. Their seeds germinate in even the smallest area of waste ground in Newcastle when they are brought to the surface by soil disturbance and exposed to light and moisture. 

Now that the site has been levelled and the rubble taken away, these plants will be on the move again - carried as seeds in rock, bricks and soil that have been taken away and probably used at another site in another part of Newcastle - part of the itinerant flora of the city.

Wednesday, November 13, 2013

Nectar in November

Insect numbers have plummeted since the first hard frosts arrived about a week ago, but ivy provides an almost unlimited supply of food for those few that are still active. The flowers continue to open well into December, although many of them will never be pollinated and produce berries. 

The first ivy flowers that open in September are almost all pollinated and produce berries that ripen in March, like those on the right of the picture above, whereas those that open after the first frosts, after insect numbers decline, are much less likely to be fruitful - like those on the left in the image above.

If you take a close look at ivy flowers on humid autumn mornings you can see the glistening drops of nectar on the surface of the exposed nectary ....

.... that are easily accessible to all insect visitors, including this small fly - one of the few insects that's still active. Although it can reach the nectar reward it doesn't make effective contact with the stamens and isn't well equipped with body hairs to transport pollen to that stubby stigma in the centre of the flower.

A few years ago observations on the vast range of insects that visit ivy flowers - including bees, wasps, flies and butterflies - prompted a group of researchers to investigate which of these was the most effective pollinator (see details of source publication at the end of this post). 

This is an ecologically interesting question because successful pollination in autumn leads to prolifically berry production in spring, providing an important food resource for migratory birds at a time when they need it most. The survival of some berry-eating birds in spring could hinge on the performance of insect pollinators of ivy in the previous autumn 

The researchers found that the most effective ivy pollinators were wasps. 

You can see here that a wasp is more hairy than is often supposed and it's just the right size to collect pollen as it feeds. It acts as a brush, picking up pollen and distributing it was it crawls across the flower surface, indulging in its taste for sweet nectar. 

So maybe we should rethink our attitude to those pesky, drowsy wasps that can be a painful nuisance once they abandon their nests in autumn and set out in search of anything sweet. Their late-season activity may well be playing a significant role in the lives of migratory birds..........

Source: Jacobs, J.H., Clark, S., Denholm, I., Goulson, D., Stoate, C. And Osborne, J.L. (2010).  Pollinator effectiveness and fruit set in common ivy, Hedera helix (Araliaceae). Arthropod-Plant Interactions 4 (1), 19-28.

For more on wasps, click here.

Wednesday, November 6, 2013

No ladybirds for months, then five species all at once.....

Thursday's Guardian Country Diary describes encounters with ladybirds in Weardale and Teesdale.

Back in the spring it seemed as though 2013 might be a good year for ladybirds locally - plenty of 7-spots seemed to have come out of hibernation so I anticipated a thriving population by the time their offspring hatched in summer - but it never seemed to materialise. I found a few isolated individuals of other species - notably 22-spot , 14-spot and an orange ladybird  but then last week .........

........ this huddle, near a pine plantation at Wolsingham in Weardale. It was the largest number of 7-spots I'd seen in one place all year: six that had chosen a split in a fence post as their hibernation site. 7-spot ladybirds aren't usually associated with conifer plantations but his particular row of fence posts, on the sheltered, south facing side of the plantation, as always been a good place to find other species

So it was no surprise to find this eyed ladybird - a conifer specialist - sunning itself on the same line of fence posts.

A small, unidentified fly with unusual up-turned antennae had even chosen to hitch a ride on it. The eyed ladybird is our largest species but ...

...... this one, a larch ladybird that shared the same fence post, is one of our smaller species ...

..... here going head-to-head with a staphylinid beetle (which it simply head-butted out of the way!)

Then, a day later at Egglestone in Teesdale I found ivy in full flower that had attracted several orange ladybirds, that were feeding on nectar.

You can see here the translucent pronotum of this species, that used to be considered scarce but seems to have increased in abundance in recent decades, supposedly because it has taken to feeding on fungi that grow on the honeydew secreted by sycamore aphids. On one occasion a few years ago I found a cluster of ten of this species hibernating on the bark of a sycamore in winter - it's certainly a species that can be added to the very small number of insects that are associated with sycamore, which has been present on these islands for around 500 years but has a very small insect fauna.

Close to the orange ladybirds on the ivy I then found a single 7-spot sunning itself on a fence post and ......

.......... scores of this very unwelcome addition to our ladybird fauna - the harlequin. The first time I saw these locally was in Durham city back in 2009, on ivy flowers at almost exactly this time of year. Harlequins are noted for their bewildering range of colour patterns but the indentations at the tail end of the elytra are also a distinctive feature, although they too vary in extent between individuals.

This group of about a dozen individuals had just hatched from their pupae and were still developing their full colours. Harlequins have a breeding season that extends well into autumn.

Some, that also seemed to be the most rotund individuals, were almost entirely black ...

..... but his was a more typical colour pattern in this population.

Finding another population of harlequins was an unwelcome discovery because this disease-resistant species is known to be a predator of our native ladybirds and can also transmit a parasite that kills other species. It also feeds extensively on eggs of butterflies and moths. Over the last decade it has spread rapidly from south east England to the Scottish border. It originated in central Asia but was introduced elsewhere in misconceived biological control programmes aimed at 'environmentally friendly' aphid control in greenhouse crops. Wherever it has been introduced it has escaped and has had a detrimental effect on native insect populations.

The predominantly black individuals seem to have blue eyes.

This was the last unhatched pupa, attached to the fence posts. At the point of attachment you can just see the remains of the larval skin, which is spiny in this species. 

Harlequin larvae also seem to have an affinity with sycamore, perhaps because of the vast supply of sycamore aphids that they find on the leaves - so it may well be that orange ladybirds will also form part of their diet too.

If you find harlequin ladybirds you can report their presence by contributing the record to the Harlequin Ladybird web site.