Monday, 23 December 2013

The classic Christmas crisis: "i think these batteries are flat"


Science sometiems depends on the right bit of kit to measure, map or probe. Personally I'm a great fan of lo-fi and mostly use a pond net and a white plastic tray. Not much that can go wrong there, although the wind that whips across Druridge Bay can pick up a tray and hurl  it across a swamp with nonchalent ease. However detailed chemistry requires proper measures and we have just got a new probe which will allow Scott to measure the chlorophyll, oxygen and conductivity in his experimental ponds simultaneosuly and live in the field. It came in a tough, field protable case which was opened with glee to reveal the shiny, exciting bits and pieces. Even came with its own screw driver. Here are Dave and Scott having a first go at starting it up in the office. In perfect synchrony with the seasons the batteries that came with it were flat. How many Christmas Day mornings throughout the UK have been blighted by that howl of anguish? You see why I like a net and a plastic tray.... They'll get it working I'm sure.

This Druridge Bay pond blog has been going for just a bit over a year now. We are taken aback by the global coverage: Russia, Argentina, South Africa, Latvia, Canada... Even if you have stumbled across Ponds, Time and Place accidently I hope something of this magical landscape has lightened your day and the mysterious lives of the pond plants and animals have captured your imaginations. Merry Christmas to all our readers.

Saturday, 14 December 2013

The ostracods eat their spinach


The three ostracods featured in the last blog are typical of their kind; widespread in small ponds and pools, especially those prone to drying, relying on tough eggs to resist drought. During the good times when ponds flood again they use asexual reproduction to churn out young through parthenogenesis, the process in which unfertilised eggs develop and mature. Despite the adults tough bivalve carapaces many predators catch these small prey. Dragonfly larvae and water boatmen have been shown to reduce populations significantly. The Ostracods respond by changing behaviour migrating to safer parts of the pond. Heterocyrpis incongruens reacts to chemical cues in the water, shifting to more open water and being less active. Moving about less is potentially tricky for male ostracods in search of a mate, although experiments to compare predation on sexual versus asexual individuals of Eucypris virens showed no marked difference in vulnerability. Male ostracods are unknown for some species, but it seems unlikely that being eaten is the cause of this absence. Asexual reproduction could have advantages faced with intense predation, because one female can potentially found a population.  Ostracods themselves seem to be rather generalist feeders but with some preferences. Eucypris virens has a liking for spinach when offered a variety of foods and also Tolypothrix tenuis a type of cyanobacterium, a combination humans are unlikely to encounter outside of an extreme sushi bar. Animal prey can be on the menu too, especially sickly or injured larger creatures, who can be overwhelmed by the sheer number of ostracods ganging up on them. ... perhaps, like Popeye,  it’s is the beneficial effects of all that spinach.
Schmit, O. et al (2012) Vulnerability of sexual and asexual Eucypris virens (Crustacea: Ostracoda) to predation: an experimental approach with dragonfly naiads. Fundamental and Applied Limnology, Vol 181, 207-214.
Schmit, O. et al (2007) Food selection in Eucypris virens (Crustacea: Ostracoda) under experimental conditions. Hydrobiologia, Vol 585, 135-140.

Tuesday, 10 December 2013

Pea shrimps: the charm of the Ostracoda



Amongst the scurrying, skipping and gliding specks at the bottom of a tray of pond life there are certain animals notorious for being tricky to identify and generally misunderstood. The jelly-bean like threesome above are all members of just such a group, the Ostracods, sometimes called pea shrimps. Most of what you can see are two valves, largely enclosing a scrunched up body with a handful of antennae, legs and other sticky out bits. They are little crustaceans, their jointed limbs at least giving away their kinship with more familiar water fleas and shrimps. Identification is tricky, largely needing a good view of the legs and antennae, “extremely difficult and can only be undertaken by a specialist ” as it says in Wolgang Engelhardt’s classic The Young Specialist looks at Pond-Life. Whilst ecologists may be wary of this awkward group geologists have a wealth of knowledge of their historic distributions, using fossils of the tough valves and the various shapes, spines and surface sculpture. Size, colour and shape are handy for the living adults and these three are fairly distinct: Herpetocypris reptans, Heterocypris incongruens and Eucypris virens. The “cypris” bit of the names is essentially saying “shrimp”. All three are a millimetre or two long, stuttering uncertainly across the sediment in search of food which can be any old detritus but they can gang up on enfeebled prey too. Although individually small their populations are robust, sustained through the ups and downs of drought and flood by desiccation resistant eggs, so they often appear in puddles and flashy pools. Heterocypris incongruens in particular seems to prefer these conditions and is lost from ponds as permanent, dense emergent plants such grasses and spike rush colonise. Under a microscope they are objects of great beauty, their valves sculpted or fringed with bristles and serrations. I am fond of these enigmatic beauties.


Wednesday, 27 November 2013

Flood, drought ... and now the plough


 The modestly named Small pond weed, Potamogeton berchtoldii, (or, less modestly, Berchtold’s pond weed, because that is what the Latin says) is nonetheless a canny plant, turning up in ponds across Druridge Bay, including unlikely sites in the middle of arable fields. The delicate, filigree strands of stems and leaves seem ideal to fragment, stick to birds and be carried between sites. This little pondweed also seems able to tough it out in exposed shallows or ponds with slightly higher salinity, which seems to come up from underground springs. Although it is a flowering plant this species relies on cloning to spread using ramets; individual plants that, together, form the whole vegetative colony. To over-winter the pondweed sets turions, essentially a bud, but a bud adapted to tough it out during the lean times, functionally akin to a seed or bulb  in other species. Just how tough this overlooked pondweed can be is under severe test in some of the subsidence ponds at Blakemoor Farm. The warm summer has seen water levels fall far enough for several subsidence ponds to be ploughed through, including the wide but shallow site featured on the blog as it began to dry out.



The cracked, dried soil from the sequence earlier in the year (2nd September blog, compare the drying sequence in the photos above to the latest ploughed state of the pond at the top of the blog) is now tilled and turned, the pond which was once the summer hang out for avocets , teal and black headed gulls is barely detectable. Whether ramets and turions cope well with ploughing I do not know, although I suspect the plant will recolonise once the pond refills. On the 20th November the site was just the bare, ploughed ridges but by the 27th a silver flash of water had puddle across the lowest part of the shallow basin. Potamogeton berchtoldii is not a rare plant: the map shows the national records from the NBN gateway data base since 1980. If anything it may be overlooked given the small size and identification challenges



Wednesday, 20 November 2013

The water beetles' sad end as a teenage heron's snack


The predatory beetles of the last two entries look spectacularly fearsome through a hand lens; pointed jaws which pierce prey and along which the digested innards of their victims are sucked out, clusters of simple eyes spots which suggest a very different perspective on their world. However if you are a 1 metre tall Grey Heron, Ardea cinerea, these beetles probably pass for a light snack. The experimental ponds at Hauxley are a frequent hang out for the young herons that have left the nest. They loiter, preen and wander round with no obvious purpose in a perfect echo of teenagers. They also throw up pellets, like the one in the photo above. Heron pellet contents vary greatly with time and place, as they seem to hone their hunting to fine grained variations in the available prey. Mammal remains such as voles and moles occur frequently, birds too, especially chicks, and the tough wing cases (elytra) of water beetles. Three large, ridged elytra, edged with a distinct yellow border are in this pellet, the remains of Great Diving beetles (Dytiscus) based on the size and colour. The victims were female beetles, the ridges a give-away of gender compared to the smooth wing cases of the males. The rarity of fish bones, even their apparent absence, from heron pellets has attracted comment in many more detailed studies. Why they should be missing is not clear, since plenty of other fish eating birds regurgitate bones and otter spraints are essentially fish bones in Earl Grey tea scented oil. The beetles’ wing cases are tough. Beetles body parts found in ancient soils and peat can be so intact that precise species identification is still possible allowing local habitat conditions to be worked out based on where the species live these days. Quite where these two female Dytiscus came from I cannot tell. Dytiscus beetles have never been found in the experimental ponds, so the herons must have travelled further afield. In true teen fashion they last leave the debris lying around when they’ve finished.

Saturday, 2 November 2013

Acilius, the elegant plankton hunter


The Acilius larvae of the previous entry repay closer inspection. Two species of Lesser Diving Beetle are found in the UK, Acilius sulcatus and the scarcer Acilius canaliculatus. The “Lesser” is the curse of sharing the same ponds with Great diving Beetles, Dytiscus species, but the Acilius have their own strangeness and charm, less of the brute force of the Dytiscus larvae or clockwork toy look of adult Great Diving Beetles. Adult Acilius resemble submarine almonds in shape and size. They are apparently the fastest swimming of the diving beetles. However it is the larvae that are most startling. They are nektonic, meaning they live out in the open water column. Legs fringed richly with fine hairs make powerful paddles, but they often hang, stationary, waiting for prey to come in reach. Whilst they will take a variety of invertebrates they are particularly effective predators of water fleas, perhaps voracious enough to skew the distribution of these prey throughout a pond and also ferociously efficient hunters of mosquito larvae. Juvenile mosquitoes have to come to the surface occasional to replenish oxygen supplies, relying on a snorkel-like siphon to break though the water’s surface to the air above. Swimming to the surface, or even static but silhouetted against the light above makes them vulnerable to specialist hunters. Whilst Dytiscus larvae routinely capture large prey such as tadpoles (or each other) the Acilius’ delicate, elongated thorax and small head make for an altogether more refined but  equally deadly hunter. (Adult photo from Old Billuck and larvae from Biodiversity Heritage Library, Creative commons, Flickr).

Monday, 21 October 2013

Bitten by the bug... and it matters which one

Ponds are a family favourite. Give a child a net and just wait for all the mysterious creatures that will turn up: fearsome water tigers and skittish pond skaters, leggy hoglice and shining snails. The remarkable variety of life that makes mini-beast hunts such a great lucky dip is also a beautifully familair version of the richness and diversity of ponds when compared to other freshwater habitats in more systematic, scientific comparisons.  The treasury of creatures suddenly revealed from under the water is special. A recent paper in the Journal of Animal Ecology is a neat demonstration that the mix of creatures really does matter, a point often lost in more anonymous counts of species, metrics of diversity and abstractions of foodwebs. Jan Klecka and David Boukai compared the mortality of prey such as tadpoles, midge and mayfly larvae when hunted by larvae and adults of diving beetles, adult bugs and dragonfly larvae. The different hunting methods of the predators and escape responses of the prey resulted in different outcomes: it matters which species live together and what they do. This harks back to classic definitions of ecological niches by the British Ecologist Charles Elton who captured the idea of the niche by comparing the idea to the various roles found amongst the inhabitants of a village: policeman, butcher, teacher.  The most voracious predators were instar 3 larvae of the Great Diving Beetle, Dytiscus marginalis, and their larvae certainly are fearsome. I avoid putting my fingers anywhere near them. Wave a twig in their direction and they rush in, hypodermic jaws agape. Larvae of another beetle, Acilius canaliculatus, were also used, extraordinary creatures which stalk through the open water, their elongated heads and thorax lending a slightly plesiosaur look, although only a centimetre or two long. Ecology is very good at creating useful models and abstract visualisations of pond-life. Nice to see the precise animals trying to sink its teeth into your finger still matters (J. Anim., Ecol, Vol 82, pp 1031-1041 doi 10.111/1365-2656.12078).

Monday, 30 September 2013

Pete and Scott publish a scientific paper


Writing scientific papers is not a natural ability, or, if it is than only for a fortunate few. Academic papers are a tortuous challenge as you write to explain what you did in as concise and precise a manner as possible, justify why what you did matters to the wider world and ultimately discuss the significance of the findings.  Such writing is by its nature an arcane technical exercise. There are scientists who can turn the sparest of language into a pleasing phrase but most of the time I’d happily let a machine do the writing. Nonetheless academic papers are the gold standard of what we produce, their status as peer-reviewed and eventually (maybe) accepted for publication furnishing them with a credibility and place in the cannon of science that is a privilege to be part of.  Pete and Scott have just had their first paper accepted. The sheer effort to write so exactly and economically came as a surprise to them. The need to check the precise format of references to meet a journal’s house style, the unexpected questions and encouragement provided by thoughtful referees, the increasingly picky arguments over the precise line widths on a graph...... all this was new territory for Scott and Pete and they should be proud. Suddenly their names are there, a unique addition, their own work, something that would not exist if they had not done it. These days academic papers are caught up in the wider pressures of rating research excellence, funding streams, and career CVs, but I can still remember the day my first publication was accepted and the shock and delight this caused me. It pays to remember that science is done by men and women, not just a string of names et al. So here is Pete submitting the paper a few months ago. Standing behind is Mike Deary, one of Pete’s supervisors, probably offering more advice which Pete is evidently ignoring.

Saturday, 14 September 2013

The pondweed's great time and space escape


Two inches of rain fell over parts of north east over the last week. Flash floods had motorists scrambling onto car roofs and the torrents carved out a gentle stream in the petite seaside resort of Saltburn into a mini canyon, ripping up tarmac and turning cars into dodgems. The end of august had seen most of the smaller ponds along Druridge bay dry and baked, with grim results for some animals and plants. For example the small leaved pondweed, Potamogeton berchtoldii, that had established in an isolated pond in the middle of an oil seed rape field in the wet summer of 2012 seemed lost (left hand photo, Blog, 2nd September). However the key to pond ecology is not to think of  a site in isolation, either in space or time. Pond-life has always had to come and go across the pondscape, finding entirely new sites as old ponds fill in or, over a shorter time scale, colonising or wiped out as the seasons and climate vary. The pond weed may have been lost from the arable pond (...although the real test will be next summer in case fragments of root or seeds sprout again from the apparently barren mud) but has turned up a kilometre away, this time in a pond in the middle of grazing pasture (right) , one of the few ponds to survive the summer drought due to an adjacent spring line.
This new site has been checked repeatedly over the preceding two years and the pondweed has not been found before, so this looks like a genuine colonisation. Repeatedly visiting sites over the years can feel like very mundane science, lacking the glamour of genetic code breaking or atom smashing, but long term monitoring is needed or else all we have are snap shots which may give a poor representation of the ecology.  The pondweed is doing perfectly well if you look across the years, but one year alone is too static; which year is representative? 2012,all pond inundated and the pondweed in amongst the arable crops or  2013, the ponds drying out, the pondweed in the pasture pond? No single year does this site justice

Thursday, 5 September 2013

The pond skater's lunch

There may not be much open water in the early autumn warmth but where the ponds stay wet life and death goes on. Pond skaters are very conspicuous right now. These are members of the true bugs, the Hemiptera, with sucking mouthparts drawn out into a stiletto-like proboscis, all the better for sucking the juices out of hapless victims. Watch the pond skaters for a while, there is an elegance and simplicity to their movement, a single stroke of those long pairs of legs is enough to catapult them across the water, then, propped on their cantilevered second and third pairs of legs, wait perfectly still on the surface. They are skittish, slightly nervous creatures when fully grown, as in the picture. Newly hatched young in mid-summer are pin-pricks perched on tiny cross hair legs.
 

Their fidgety nature hides a murderous intent. These are predators, specialising in other insects trapped in the surface film. The skaters’ impressive water geometry is a patrol in search of prey. They react to the vibrations of water logged wings or twitching legs by sidling up, ever so nonchalantly, inspecting their target for signs of danger. Then, if they sense no risk, they move in for the kills. Once a prey item has been stabbed they find a raft or bankside refuge to which they  retreat and enjoy their meal.  Sometimes several skaters home in on one victim, resulting in a flurry of skips and hops, legs seeming to go all over the place as they jostle for position. The skater in the picture has harpooned a Bibionidae fly, and there are other flies and a frog hopper mired in the surface tension nearby, as well as smaller flies perched on the water surface in search of their own, tiny prey. The skater is using the feather as a platform on which to finish its meal. Stylish, but deadly

Monday, 2 September 2013

The pondweed's doom

The wet summer of 2012 saw many more of the temporary ponds stay full all year long, especially the shallow flashes and pools in the arable fields. The bare mud may not look an inviting habitat but for the few species that can cope these ponds are a productive refuges. Some more unlikely inhabitants turned up too, notably some plants typical of more permanent water. The left hand picture shows a dense clump of small pond weed, Potamogeton berchtolidii, flourishing in the  exposed shallows of a large pool in the middle of what should have been an oil seed rape crop.



This particular pool fills every year, a distinct dimple at Blakemoor farm not far east of the A1063 road. How the pondweed got there I do not know, although black headed gulls, shelduck, red shank and avocets all loaf around on the muddy margins and may be the vectors. The summer of 2013 has been drier, in fact the warmest, driest since 2006. The middle photo shows the same view in May as the water level falls. Fragments of small pondweed were still scattered across the bed of the pond, hard to see but there is a clump in the red circle. However by the end of August the water had receded leaving the mud to crack and gnarl (right hand image). No pondweed could be found on the crisping surface. Perhaps buried roots will allow the pondweed to re-grow and the pond refills over winter; it will take until next year to find out. It is not often you witness these moments, whether the unusual arrival in 2012 or grim fate of 2013, but pond wildlife is surprisingly mobile and small pondweed is a common plant of many of the permanent ponds. The drying out bowl of the pond is now ringed by chickweed, Stellaria major, and Orache, Atriplex prostrata, much more typical plants of these sun baked field pools.

Friday, 2 August 2013

A high summer midge hatch

High summer time ponds can be slightly disappointing for their animal life as the larvae and juveniles of so many insects which thronged the ponds in April and May hatch and fly out to become, often very briefly, terrestrial. The productivity of the ponds is a subsidy to the food webs of wider landscape. For a few species such as dragonflies and damselflies the glamorous and gaudy adults are a much admired addition to the sights of summer. Along Druridge Bay Blue Tailed damselflies (Ischnura elegans) and Common Blue damselflies (Enallagma cyathigerum) are particularly widespread and Southern hawker dragonflies (Aeschna cyanea) are also beginning to patrol some of the hedgerows and lanes. Few of the other insect life hatching from the pools attracts much interest or favour, instead mostly complaints as various midges and mosquitoes fidget around us. The shallow ponds and flashes in the arable fields are particularly good for some midges, members of the Chironomidae Family (non biting midges). The particular species that are most obvious are from the genus Chironomus, conspicuously red, and wiggling in a slightly lazy figure of eight if you stir the mud. Individually they seem small and perhaps insignificant, but the photo above shows a wind-blown line of their discarded pupa cases, left behind as the adults emerge. The open rims  of the cases, split along the back where the adult hauled itself out, are water repellent, hence the sharp edges. Thousands have made it from the muddy field pond. These temporary sites are seldom colonised by predators such as diving beetles of sticklebacks which can exterminate these midges. Ducks and waders take a toll, leaving their prints in the mud, but the midges still hatch in their thousands. The midges themselves feed on fine particles of organic debris and algae which they scrape and graze. The ponds can show vivid mats of algae carpeting the mud, the whole pond briefly very productive for the few creatures that can cope with the urgency to hatch, grow and mature before the water dries out. The midges make ideal food for dragonflies too

Sunday, 28 July 2013

To the Bronze Age in search of a Tsunami

In 2012 Druridge Bay’s ponds and wetlands teemed with invertebrates flourishing in the summer-long floods and were waist deep in rushes, grasses and herbs. This summer the ponds dry and crack in the July heat-wave, their wildlife hunkered down, plants desiccated or grazed as livestock can now reach the swards that were behind deep moats of unseasonal flooding last July. These two years capturing a powerful example of how the ecology changes, but the Bay currently offers a more striking example of changes through time and landscapes, but also of human continuity. Along the dune front at Low Hauxley Archaeological Research Services are leading a dig to record the Bronze Age burial sites that had been revealed as dune erosion cut into a burial cist. The dig, "Rescured from the Sea" has been a revelation. The occasional burial remains had been known for many years but the dig has unearthed two arcs of large stones, the half circle outline of a Bronze Age cairn (far edge of site in photo), the outer half having already been washed away by the tides gnawing at the dunes. A few metres inland, and unexpectedly, an Iron Age round house is traced in the sand (right, foreground), with at least two hearths and what one digger described as a crazy paving patio out the front. Stone Age finds have also appeared in the concreted sand base of the site, perhaps from the same people who left their foot prints in the peat beds which are occasionally unveiled when winter tides rip back the sand from the adjacent beach. The Bronze Age site looked across a kilometre of land to a distant shore line, a world of wet woodland populated by red deer, wild boar and huge wild cattle known as Aurochs, a world which has been preserved in the peat beds along the dune face (Blog, 5/12/2012 and 10/12/2012 ). The continued use (or perhaps revisiting) of the Hauxley site from Stone Age, Bronze age through to Iron Age is a compelling tale and perhaps one laced with startlingly sudden change. The archaeologists are now digging down at Hauxley to search for evidence of the North Sea Tsunami, which occurred ~8000 years ago, a tidal drive driven by colossal undersea sediment slides, the Storegga slides, off the east coast of Norway. The floods of 2012 and heat wave of 2013 are much smaller events, but work with the archaeology to show just how dynamic this landscape can be. The diggers happily show you around at 11am or 1pm everyday, so get along and take a trip through time

Friday, 19 July 2013

Cows, coypu and the ectozoochory taxi

A July heat wave has clamped down over England. Radio Newcastle asked people to text in with the temperature in their office or car; often over 30oC. Up at Druridge Bay the dune grasses are being spun into sward of the finest golds and silvers, bleached and glittering in sunshine. The ponds which last year were overflowing have largely dried. The few which retain a hint of damp have become a haven for cattle, a mini-migration. Here is a subsidence pond at the south end of the Bay, in a pasture field, the cattle homing in on the cool soil amongst the grasses and rushes left by the hay cutter. The cows seem to mark out the pond’s outline with a precision to match any surveying I could do. The drying out is compounded by heavy grazing and quite bit of pooing.
This pond was a verdant swamp of spike rush and jointed rush a year ago, but the clumps of rushes are now bitten down to stumps and the mud poached by hooves. I’d like to know if the livestock can carry pond life from site to site; ectozoochory, to give hitch-hiking on an animal its scientific name. Whilst the expansive bulk of cattle seem a likely form of transport smaller animals can be good vectors too. One of my favourite studies is of things washed from the fur of coypu living (or, had been living) in the Carmargue in the south of France. The coypu had been shot, not part of the study, but as a control programme and Aline Waterkeyn and her colleagues hosed down the corpses to see what the coypu had been carrying. Waterfleas and rotifers, midge larvae and worms, Ostracods and springtails all came off in the wash (Hydrobiologia, vol 652, pp267-271). The water-fleas were particularly species associated with aquatic plants, which fits the herbivorous habits of the coypu. I have a soft spot for coypu, having watched them when I grew up in East Anglia. They would come out of the wetlands and “moo”, slightly forlorn, as if aware of their unloved status. I tried coypu curry once too. The coypu are gone from England now, eradicated due to their impact on crops and river bank defences. Like the coypu of the Camargue the cattle of Druridge Bay are likely vectors, and they moo.

Monday, 8 July 2013

Bad year, good year. Or, perhaps the opposite

The photos above show the margins of a subsidence pond in one of the pasture fields north of Cresswell village. On the left hand side the pond in July 2012, as the record breaking wet summer swelled the wetlands throughout the Bay. To the right the same pond in July 2013, as the first proper heatwave since 2006 takes hold. The weather during 2012 was a startling combination, opening up with a lingering winter drought that broke in April, to be followed by weeks of high rainfall punctuated by occasional exceptional downpours. Homes were flooded, roads closed or washed away and crops destroyed. Wildlife certainly suffered, most conspicuously the familiar butterflies of summer with the often overlooked cabbage whites suddenly becoming things of rare and flimsy beauty. This year seems better, although the high summer skippers and brown butterflies are taking their time to first appear on the wing. But which pond looks in the best health? In 2013 the same pond is but a puddle, the rushes and grasses stunted and grazed. Admittedly in 2012 no sheep or cattle were kept out in the fields, instead taken inside to weather the weather, so this year the verdant grasses, including the likes of the very palatable Flote grass, (Glyceria fluitans), have been nibbled to stumps. Again, 2012 looks in retrospect, like a boon year for many of the wetland plants.

Thursday, 27 June 2013

Parliament, ponds and extreme weather

The Houses of Parliament are so familiar that it is easy to forget just what an extraordinary confection of ornamentation they are. There is not a square inch lacking in Victorian flourishes of heraldic arms, gothic crenulations and worthy relief sculpting. Standing outside the Palace the whole structure radiates a slightly alien feel, as if inside its own protective force-field amongst the throng of tourists. I was there for the launch of The British Ecological Society’s latest publication, a review of the impacts of extreme weather on freshwaters in the UK. A tricky document to pull together because studying extreme events is an ad hoc science, replying on unforeseen opportunities as drought or flood strike the UK and often lacking reliable data from before the crisis against which any impacts can be judged. Nonetheless the review pulls together evidence from lakes, rivers and ponds and paints a fascinating picture of the changeability and resilience of our freshwaters. The broad message is that our freshwaters are vulnerable and can show rapid degradation, but nature bounces back so long as there are refuges elsewhere in  catchment or wider landscape from which the wildlife can recover (the whole document can be downloaded at http://www.britishecologicalsociety.org/public-policy/our-position/ecological-issues/)
Northumberland, and Druridge Bay, feature large in the review, because I helped write the report and they are what I know best. In particular the Hauxley experimental ponds are an unusual example of a long term study, around long enough to have been hit by extreme rainfall and prolonged droughts. The impacts of the June 1997  deluge in Northumberland, an event so unusual that it may be a 1 in 300 year event, are shown in the report in photos of the River Wansbeck strewn with ripped up bulrushes and the Hauxley ponds are pictured because of the thick mats of algal that developed when the ponds did not dry out, with the result that other wildlife was partly smothered out. Odd but also charming to be thinking of Druridge Bay and Hauxley in the wood panelled grandeur of the palace of Westminster, crackling with power and the hushed sound of crustless finger sandwiches being hoovered up.

Friday, 21 June 2013

Ponds and the creativity of extreme weather



2012 has become infamous as the wettest year on record in England. Infamous, at least, in England. This has been followed by a peculiarly long winter, the coldest for fifty years. Britain has had a run of wet summers. One outcome was a recent meeting by climate scientists hosted by Exeter University to try and make sense of the signals from the noise and ,perhaps, the causes. The immediate driver appears to be the jet stream, which has not been shifting as far north has it once did and, instead, acts as a conveyor hauling Atlantic depressions across the UK, one after the other. However what causes the jet stream to linger so far south remains unclear (http://metofficenews.wordpress.com/2013/06/18/meeting-on-uks-run-of-unusual-seasons/) . Ponds make immediate and powerful indicators of the impacts of these variations in our climate. The photos above show one of the subsidence ponds at Blakemoor Farm in the summer of 2012, when it was festooned with deep banks of Celery Leaved Buttercup, to summer 2013, when it has dried out, leaving a few forlorn tufts. What is the most worrying; being awash or being dried out? Neither. The pond comes and goes and with it the vegetation. The animals are less obvious but they too wax and wane between years. The extreme year of 2012 created an opportunity for plants and animals that seldom colonised or, even if they did, dominated the ponds. The ability of a landscape to vary  has always struck me as important, although a tricky thing to measure, given how short term so much of our research is. We find it hard enough to describe what we can capture and count, letalone something as abstract as the potenital to change. The variation between years has added to the overall biodiversity, allowing wet and dry year communities to flourish. The risk is that we have not recorded enough data for sufficient years to spot any major step changes, those thresholds beyond which the stage is re-set and some of the cast of ecological characters  never re-appear.

Saturday, 15 June 2013

The fairy fern hints at summer

There are signs of summer in a bucket in my back yard in Newcastle: the fairy fern has sprouted green shoots. Green, feathery branches have grown out from a reddish base, visible in the photo amongst the smooth round duckweed plants. Fairy Fern, Azolla filicoides, is a native of the west coast of the USA, not that these tiny individuals came over the Atlantic. They came from Ellington at the south end of Druridge Bay. The large pond in the village has harboured these New World arrivals for many years. The ones in the bucket in my back yard were a test to see how they would fare through the winter, being plants of warmer climes. Would they cope with being iced up? They were frozen into a solid block of ice, the ferns turning a blotchy red, which seems to be a cold weather response, but they survived and now are sprouting delicate, doily-like new growth.
 

In a warm year they form a dense mat over the surface of Ellington pond, deceptively like a lawn but, on closer inspection, a serrated fuzz of fronds oddly resembling the jagged canopy of a conifer plantation in miniature. For me the dense mats seem to coincide with drousy, heavy weather, thunder threatening through the heat in late August. In a bad year, when the cold and wet do not suit their west coast roots, they hunker down in circular rafts, nestled amongst the other plants around the edge of the pond. The managers of Ellington Pond have tried to be rid of it, but even one tiny frond is enough to retain a bridgehead and begin the recolonisation. Quite how Azolla got to Ellington remains a mystery and the fronds have not turned up further north in England, although a scatter occur throughout the Central Belt in Scotland. There is a touch of exotic mystery to its presence, almost a glamour, entirely consistent with the Bay’s sense of being between worlds.

Saturday, 8 June 2013

The fret of June

June opens with a week of proper summer warmth, an immediate slap of sunshine you can feel faintly crisping you skin. Sunny days along the Northumberland coast can have a mysterious quality. Out over the sea there are low banks of grey and brown clouds that drape from horizon to horizon a bit like those curtains around beds in hospitals. The North Sea is lost behind them. These are banks of sea fret, condensing out over the cold water. Up at the Bay the fret has been advancing and retreating in probing attacks. Tongues of sea mist drift in for an hour or two, swathing a field or dune, the sun still visible if you look up through the shallow pall of mist, then pulling back to the sea. The fret brings a tingling, hair-on-the-back-of-your-neck drop in temperature as the moisture drifts past. The droplets shred and catch on hawthorn and bramble, traces of mist visibly rolling and tumbling inland then retreating back to recharge out at sea. This has been a dry spring and the subsidence ponds in amongst the field drops are shrinking, some barely wet. The deluges of 2012 resulted in verdant borders of Celery Leaved Buttercup, Toad Rush and Pineapple Mayweed turning many of these pools into vivid summer circles, but 2013 threatens the opposite. This begs a question of those of us who regularly survey pond sites: is one year’s data, a snapshot, sufficient to characterise a pond? Probably not, or, at least a snap shot cannot capture the extent of change across the pondscape. Some ponds do not seem to vary much from year to year. For others the very variability is their most striking feature. One boon to the work at Druridge Bay is that we have got to know the sites well and have sense of time as a factor in the ponds’ ecology. This year I’ll be re-surveying the vegetation of the ponds at Blakemoor to compare to the summer 2012 plants. For now though I’m enchanted by the fret seeming to briefly stop summer and hide the ponds from our gaze.

Sunday, 26 May 2013

Students of pond difference

I’ve spent the last week in the Lake District with our first year undergraduates on their annual field trip, a mix of core ecological skills for conservation and landscape in the UK (Phase 1 mapping, National Vegetation Classification), ping pong and stone circles human sacrifice re-enactments. They worked hard, twelve hour days, apart from the final night when they stayed up even longer to craft the data they had been collecting into presentations. Creating a pressed flower collection may not seem  the most compelling activity when you are 19, but I am confident those slightly mangled specimens of pignut and pink campion will one day be treasured possessions. Each student had a particular flower to find, hampered a bit by the late spring but also resulting in a bout of botanical blind man’s buff, watching them walk past their quarry. They have to do a group project too. One five-some, Ryan, Chloe, Dylan, Andrew and Jack took up the challenge of comparing the richness of invertebrate in two ponds compared to two streams. We’ve not tried this before but after several days of counting grasses in quadrats you can see the attraction. They took kick samples from two streams coming off the southern slopes of the Blencathra ridge up by Skiddaw, then samples from two nearby ponds. The streams yielded Heptagenidiae and Baetidae Mayflies, Leuctridae and Chloroperlidae stoneflies and a supporting caste of oligochaete worms and cranefly larvae. The two ponds were more of a surprise, both teeming with tadpoles but otherwise rather different, one pinging Copepoda zooplankton and creeping Nemouridae stoneflies, the other with Polycelis flatworms, Pseudocrangonyx gracilis shrimps and the giant Ramshorn snail Planorbis corneus. They used Jaccard’s Index of Similarity to summarise these patterns, essentailly a measure of how many taxa two sampels have in common ranging from none, 0%, to an identical inventory, 100%. The two streams were 50% similar to one another, the two ponds only 17% similar to each other, a neat demonstration of the heterogeneity of ponds in the landscape, and a neat demonstration that students can do good work given the opportunity plus  staff suffering from an overdose of Protestant work ethic and slightly sleepless nights.

Sunday, 19 May 2013

Spray time at Blakemoor


The subsidence ponds at Blakemoor Farm at the south end of the bay are so familiar to us that we forget how startling they can seem to visitors. The pond in the photo above swells across a hollow in the middle of a large arable field that is given over to oil seed rape of winter wheat. The extent of the water varies markedly with seasons and years. A dry summer can see the whole shallow basin exposed into a reticulated pavement of cracked mud, dotted with pineapple mayweed and knotweeds. A sudden rain storm can refill the whole hollow. This is one of the ponds over the ten abandoned seams of nearby Ellington pit. The coal measures extended far out under the sea, but were so near the sea bed that the miners could hear ships passing overhead. Many of these field ponds lie in suspicious rows across the fields, perhaps echoing the subterranean tunnels. The wet year of 2012 and dry winter of 2013 has left the crops stunted and patchy, much of the ground dried out to a tough crust. The crop sprayers have been out to catch the first sustained spring warmth. We are curious to find out if any of the farm management affects the productivity of the ponds. These arable field ponds black foetid mud of the deeper swamps which seems a better trap for organic carbon. However these field ponds can be carpeted by vivid turquoise and green crusts of algae, visibly fizzing trails of oxygen bubbles on sunny days, so may be briefly but intensely productive whilst the sumemr sunshien lasts. The sprayers do not drive through the cloying mud, perhaps nervous of just what lies beneath (or, more ominously, does not because it has all been dug out) from the days when mining dominated south east Northumberland.

Sunday, 12 May 2013

The cook, the core, its bung and his oven

After several decades working in the sciences I am still troubled by the awkward conventions of neutrality that were drummed into us as students, for example how we must not to write reports or academic articles in the first person. No “I” or “we”. “Data were collected” or “this report demonstrates”, as if data collects itself or reports self-publish. I let “I” sneak into work these days, partly as a reminder that research is carried out by people. For example Pete who, in the photo above, has our new corer wedged into the oven of his flat. The new corer is a marvel of practicality. The bottom end of the tube is sharpened and has cut through sediments that are reinforced with a lattice of bulrush rhizomes as easily as it does through softer muds. The top of the tube has extra flanges so you can push down with your foot too. A wooden plug allows the sediment to be pushed out, the plug attached to a calibrated rod so we can measure precise slices. It is this plunger which has caused trouble. It is beautifully cut to be flush with the inside circumference of the core tube, but the wood has swollen in the water and got stuck. Dave says this would not happen if it were made of mahogany wood. So, in addition to the elegant steel engineering we can perhaps add a touch of high class woodworking. Meantime Pete has stuck the core in the oven to dry out the bung. This is a fine example of the “we” in science. Dave designed the core; that is a real skill. Pete has been trying it out in ponds containing glutinous goo through to others solid with roots and rhizomes; that is a real skill too. Getting a corer that works slickly and effectively across all these pond types is important so that we can take equivalent cores and slice the columns of mud into similar sized discs to compare the amounts of organic material trapped through the varying depths of mud. Because the corer allows Pete to extract precise, replicate samples he has been able to work out the density of carbon buried in the sediments. Meantime I am glad he will have to explain why his remarkably well equipped kitchen has a mud corer stuck in the oven and not me. That is quite another skill.

Monday, 6 May 2013

The waterboatman's gaze

As spring begins to take hold it will soon be time for one of my favourite pond creatures to make its presence felt. This is a Greater Waterboatman, called the backswimmer in North America, one of the aquatic bugs. They are common enough, emerging from a net scoop of weed and debris with a twitchy, gangling urgency or to be watched hanging under the surface film of a pond, the occasional subtle scull to shift them in search of victims. They are predators, snatching prey with the first two pairs of legs and using that elegant proboscis you can see in the picture extending back from the head, to skewer prey and digest their innards. They are especially good at dispatching other insects that have got snarled in the meniscus or that bumble around at the surface. Amphibious beetles such as Helophorus are particularly vulnerable. The beetles have hard exoskeletons but the waterboatman stick their proboscis between the beetles’ head and thorax, resulting in a characteristic decapitation that you can use to count attacks as the forlorn, headless beetle bodies accumulate. Much like an expert wine waiter using a corkscrew. Mosquito larvae which need to rise to the surface to recharge their air supply or water fleas, twitching in the water column, are also an easy meal. So voracious are the waterboatmen that they can exterminate their chosen prey from small ponds, eventually turning cannibal when all the easy meals have been exhausted. Female waterboatmen lay batches of eggs on plants or stones (this varies a bit with species), which hatch into black specks of nymphs, rowing urgently in search of tiny prey or to avoid their older cousins. keep an eye out over the next few weeks as the race to eat and not be eaten hots up.

Tuesday, 30 April 2013

The humble amateur

I must have had this book since I was 11 or 12, the title being one of the “Wayside and Woodland” series, a veritable “...library of books on the countryside....”. The text aches with a charm and pensiveness long since swept away except in retro advertisements or television comedy spoofs . The photograph plates have a dense, fuzzy colour or the densest black and whites. The appetite of the Hydra is “insatiable”, the prey of Dytiscus beetles are “unfortunate victims”, the chirruping of Lesser Waterboatmen “is believed to be of significance in mating”. However page 42 has hung heavy over my pond dipping. “It [the study of ponds] is moreover a field particularly suited to the activities of the amateur, whose humble pond hunting, if carried out systematically and carefully, may well result in valuable contributions to science”. What was probably meant as gentle encouragement ends up crystallising the thought that ponds may not be worthy of sharper minded ecologists. The last twenty years has witnessed a renaissance of pond science, led in the UK by Pond Conservation, (check out http://www.pondconservation.org.uk/ ) who could claim to be a fine example of Mrs Thatcher’s contribution to conservation, the Man Power Services Scheme, which metamorphosed unemployment benefits into more positive activities whilst keeping the recipients off the unemployment statistics. It was Pond Conservation who began to compare ponds directly to lake and river wildlife, revealing the importance of ponds for the sheer numbers of plants and animals they supported compared to larger lakes and longer rivers. Now that must count as a valuable contribution.

Sunday, 21 April 2013

In praise of craneflies


Here are some curious creatures from Hauxley last week. Scott spotted the left hand one as it lay, elegantly submerged, just beneath the surface of a pool. At the hind end a corona of short tails clad in a dense fur of water repellent hairs breaks the surface tension and allows the creature to replenish its air supply. The other two maggots turned up later in the week, at first glance apparently the same species but the middle one has tails festooned with wispy tufts, whilst, on the right, the larva ends with delicate lobes and what look like two eye spots but are the opening plates leading into the trachae breathing tubes that ramify the length of the body. That left hand one is substantial: 3cm of ominous twitching, a small head reaching back and forth, the jaws gnashing. The other two are not so big but, again, you can see the retractable dark head and mandibles. All three are larvae of craneflies (the family of flies called Tipulidae). Cranefly maggots thrive in damp soils, swamps and ponds, shredding leaves and other detritus with those tough jaws. They are not glamourous insects. There is not a Cranefly equivalent of the British Dragonfly Society or Balfour Browne Club (a sort of train-spotting club for water beetle enthusiasts. I should know, I've been a beetle train-spotter for 30 years). I do not know precisely which species these craneflies are (I don't know imprecisely either, to be precise), nor much about what they do, the habitats they prefer or why they should turn up this year but not last. The larger one was widespread in the Hauxley ponds this week and grown fat on what they offer. When the behaviours of pond invertebrates have been observed in detail they commonly show complex and nuanced natural histories, with precise behaviours and tolerances: for example, where water boatment will or will not lay eggs or damselflies changing behaviours in response to different predators and water beetles sensitive to changing structural densities of weed beds. These cranefly maggots are probably just as particular in their ecologies but remain mysterious.

Wednesday, 17 April 2013

The heron and the fast flatworm

January’s blog  highlighted the striking ability of pondweeds to get to unexpected places, considering that they can neither fly, walk nor swim under their own power (12th and 19th Jan). Here is another neat example of colonisation from Hauxley Nature Reserve. A few weeks ago we dug out some brand new ponds amongst the older experimental ponds from which I’ve recorded the invertebrates since 1994. The new ponds look raw: in the left hand photograph you can appreciate the unlovely bare mud, sheer sided and often clouded with muddy water. But look closely in the bottom left and there are the elegant prints of a heron which has deigned to wade through, and, amongst the heron’s tracks the dark, gliding oblongs of flatworms (right hand picture). They are species of Polycelis, either tenuis or nigra but hard to tell which without dissecting their reproductive organs and this is not that sort of blog. Polycelis are hunters, which suggests that there is something to hunt. Small Hydroporus water beetles and Crangonyx freshwater shrimps were also evident. All these creatures and numerous in the pools around about and have moved into this new home readily. The original ponds from 1994 also colonised very quickly but with a slightly different fauna of pea shrimps and water fleas. This new round of ecological succession may be different because the adjacent older ponds, spring boards for colonisation, harbour a more varied fauna.

Thursday, 11 April 2013

The liver-sausage slicer

More core try-outs. Here are Pete and Dave experimenting with the new, hand welded, Dave designed corer (unveiled on the 5th April blog). The metal core tube has a plunger allowing us to gently push out the sediment samples, the plunger handle calibrated to measure out 1cm sections which are then sliced off. The sections from this core were strikingly similar to liver-sausage, a kind of processed meat that seemed to dominate 1970s Sunday tea-times, with its distinctive grey-blue-brown patina and deeply savoury taste. I had assumed liver-sausage had become extinct now that our supermarkets are full of rustic treats from across the whole of Europe but Pete assures me it was all he ate in the second year of being a student. We can now cut up the cores immediately in the field rather than bringing them back to the lab and struggling to detach them from tubes. This core came out of a pond that lingers along the headland of an arable field at Blakemoor Farm towards the south end of Druridge Bay. The fine sediment gets ploughed and driven through occasionally and the pond lacks the dense swards of swamp plants that seem to be associated with the darker, organics rich mud. We suspect these arable field ponds are much less effective at trapping carbon, although the surface of the mud can often be a vivid mosaic of green algae bubbling out oxygen on sunny days. Over April we hope to core a range of pond types to characterise the organic carbon that has buitl up in their sediments. Dave's corer looks the business.

Friday, 5 April 2013

The engineer and the Harrod's toilet brush


Newcastle upon Tyne, where we are based, has proud tradition of engineering. There is a lingering scatter of ship yards along the Tyne now used to pamper North sea oil and gas rigs and, over in the west end of the city, a massive workshop constructing armoured vehicles where once lord Armstrong's yards supplied battleships to the world. The heyday of engineering has largely gone nowadays, leaving a strange flotsam in the Discovery Museum which has galleries of shining engines, pistons, motors, winders, winches and mills. In the days of digital the knack of manufacture still has its place and research often brings out the best. We have been struggling with how to take a core of sediment from the ponds. We need to be able to drive down into the thickest mud, sometimes through mats of roots, pull out the whole core and not lose the gloop at the top. Dave has lovingly designed our very own corer, all the state of the art standard ones having proved a failure. Hand welded is resembles a hydrid between a bazooka and broadsword. We tried it out in the sudden sunshine up at Blakemoor farm on Thursday. The substantial metal pushes into the mud with satisfying substance, unlike some of the flexing and buckled plastic tubes we have tried. Dave laments the absence of foot braces to help push down but I’m sure they can be added. The metal tube has a cunning, calibrated plunger to push out the core. The only thing we need is something to clean out the inside of the tube between cores. Dave has the answer: a toilet brush from Harrods. This is the charm of research. Here we are struggling to pull out plugs of mud, accurately and precisely to measure weights and volumes and this has required a craftsman’s eye for design and an inexplicable bit of top quality bathroom shopping.

Tuesday, 2 April 2013

The ponds' Antiques Road Show

The month of March may have been cold but there has also been little rain. No wonder many of the shallow field flashes have dried out since November. The ponds of south east Northumberland have changed over the decades too. Here are some simple data from a talk I gave last week to the north-east branch of the Institute of Ecology and Environmental Management. Always glad to have people turn up; I still fret that ponds don't quite have the allure of the Large Hadron Collider even though ponds are especially rich in wildlife compared to the large lakes and rivers that dominate the imaginations of policy makers. The data are for the south east corner of Northumberland, in a triangle roughly from Amble, at the north end of Druridge Bay, south to Newcastle inland and Tynenouth, the latter at the coast. I counted all the ponds (...and moats, troughs, tanks and the like) I could find on 1:10,00 Ordnance Survey maps across all the historic editions. "Survey" in the table above shows the survey edition dates when maps were revised. Okay, it is not a complete pond census, only an audit of ponds that appear on maps but those Victorians in the Nineteenth Century were very detailed map-makers, capturing features down to 4 metre diameter. The overall number of ponds has not changed much, but the turnover of individuals ponds has been considerable, with an conspicuous late surge led by golf courses. The general increase in recent years matches data from the UK countryside Survey and recent audits by Pond Conservation. Which should be good news, unless all those old ponds were superb wildlife hotspots compared to these new sites.

Friday, 29 March 2013

"....til the wild geese have flown"


Shakespeare’s King Lear reckoned winter lasted until at least their departure. The cold has kept us indoors but Druridge Bay is exquisite in winter. Thursday morning I was up at Blakemoor and Ellington, the pastures still empty of ewes and lambs, the arable fields with bedraggled winter wheat rotting away. The North Sea has been churned all weak into a deep iron blue. Theatrical sheets of snow whipped in, the sort of snow dry as polystyrene bobbles, bouncing off jackets and hats. The easterly blast blew in some surpirses; a taxidermist asking me if i'd seen his friend who he'd lost searching for the wreck of puffins that has been washing up all week. The final snow wall was trailed by a barn owl, drifting in on the eddies behind the snow front. I was out doing the first complete census check of ponds. As usual there were surprises, many of the shallower sites dried out but many of the tiny pools and ruts in gateways more conspicuous. the number and extent of ponds chnages significantly with season and year, which begs some tricky questions for surveys which rely on just one snap-shot visit in one year. A few dollops of frog spawn wallowed unconvincingly. We are keen to get out and collect a full range of sediment cores from across the range of pond types, but have been waiting for some new corers after our experiments with open sided screw-cores out of which the runnier top sediments dribbled (see 1st March blog). This has left Scott and Pete largely stuck in front of computer screens. However Dave Cooke has been welding and forging a new design. If the wild geese ever leave we will soon be back out.

Sunday, 10 March 2013

Wrong place, wrong time

The deluge and floods of 2012 have barely receeded, both from memory or the landscape and winter has lingered on into early March. Here is a stiking recollection from last summer; the scatter of silver shards are a shoal of sticklebacks marooned and doomed on the path to the hides at Druridge Pools. The water had overwhelmed drains and ditches, creating a single washland from the Pools across to the dune tracks. These sticklebacks had ventured out beyond their orginal home, as all species have to, at least some individuals (see blog 19th November for flying molluscs, 12th Jan for airborne pondweed) . This swarm's bad luck left them in trackway puddles as the high water receeded. Reminds me of those fossil fish beds in museums, which conjure up a picture of ancient pools and their floundering inhabitants. I quite often splash through scattering shoals on other paths and tracks around the Bay; adventurous sticklebacks seem ubiquitous. Others will have made it to new pools, their good fortune a curse for many of the invertebrates which are vulnerable to these voracious mini-hunters.

Friday, 1 March 2013

Pete explores pond types



Up at Druridge Bay the seasons are teetering. Winter’s sodden fields are still gluey wet, swathes of wheat shoots bedraggled or long dead. The calls of geese and the widgeons’ whistles carry in on the wind, but the robins are singing for spring and busy swarms of goldfinches decorate the headlines. There is a growing busyness. January and February have been relatively dry so we have started a central aim of our research: characterising how different pond types vary in their carbon capture. “Pond types” sounds like another quagmire as bad as lakes vs ponds in the last blog. How to describe ponds depends on what you want to know: could be done for their conservation value using scores for lists of invertebrates or plants, or by the nutrient levels or pond histories. We are starting with four broad types: (1) ponds in arable fields, which are usually temporary and support few plants, (2) ponds in pasture, often covered with fodder grasses but some amphibious species too, (3) the dune slacks and flashes overlying sand soil, vulnerable to occasional brackish overflows and (4) the permanent, plant rich wetlands. The photos show Pete coring a grass ley and amongst dune slacks at Blakemoor. Sounds easy but we have hit a snag immediately. The corer works well, screwing down into the mud but when we gently teased it out the top layers of mud dribble out. These upper layers are especially dark and rich in organic debris, we must capture their presence in the samples. Research is like that. Sounds easy, go out, drill in a core, take out the sediment, go back to the lab..... I like the practical struggle, working out how to engineer the equipment, which is often more a visit to B&Q DIY than Large Hadron Collider.

The recce proved useful though, revealing dark, perhaps anoxic mud under the apparently normal sediment surface of the grassy ponds and the distinctly sandy soils underlying the dune slacks. The photo above shows the grainy sand to the right in a core from the dune slacks under about 10cm of gooier mud.

Sunday, 24 February 2013

"it's a lake"....

Pete is looking out over Druridge Pools, a glittering wash land of late winter submerging the verdant meadow. The Pools lie about half way along the Bay, on the north side of the site a deep lake that was once opencast, to the south the old mine infilled and landscaped and now a mirror to the sky. There are supposed to be five distinct ponds here, often hard to pick out low amongst the burst of rushes and wetland grasses. There are also lost ditches and sudden soak-aways: I know from gingerly feeling my way across the field a couple of years back, recording the plants whilst swallows scalpled the air, winnowing the mass of midges, and damselflies flickered around my feet. I tried to keep count but I was more concerned to keep balanced. Dave Cherry, a final year undergrad at Northumbria, has taken some sediment cores across the ponds in the summer of 2012. As with the other permanent, vegetated sites the organic carbon levels in the upper sediments proved markedly higher than in the soil adjacent to the ponds. Pete and I were checking the site to include in our first season of major sampling effort, but as Pete says “it’s a lake”. Which begs the questions when is a lake a pond? One of those questions I always get asked whenever I do a talk. I suspect everyone knows ponds when they see them, which can be confusing when they look like a lake

Wednesday, 6 February 2013

Back to square one

January ice and flood has kept us away from the experimental ponds at Hauxley Nature Reserve, but Scott, Pete and Dave were out at the end of January to begin regular recording of water chemistry, comparing three of the original ponds which were dug out in 1994 to their newly excavated neighbours. The new ponds are clouded with muddy water, the clay seeming to be whipped up by storm and wind. This is how the ponds first looked eighteen years ago too, but soon settled down, the water clearing to leave a faint blur of green algae. Pete is using a portable probe to measure the conductivity and pH, and waters samples will be taken back to the lab to determine nutrient levels, particular phosphate and nitrates. These can be surprisingly variable but that has more to do with the herons who loaf and preen and poo amongst the ponds. The new ponds also beg an ecological question: will their wildlife develop along the same broad pathways as their original inhabitants did eighteen years past? The first two or three years after 1994 were dominated by species thriving on the bare mud, amongst the strands of algae or a twine of Stoneworts. However the ponds are now surrounded by a changed landscape, with a rich cast of wildlife in the adjacent ponds. Perhaps a new sequence of species will colonise, or the old familiar species but faster. I am curious to find out, having recorded the animal life in the ponds ever January and early summer for ten years. It is partly a test of serendipity and history. Will the animals and plants reflect the stark clay walls and bed of the new ponds or will the wildlife be more the result of the variety of species around about, their availability overcoming the limitations of the raw habitat?

Thursday, 24 January 2013

Why Druridge Bay needs Warthogs

Birds might seem the obvious carriers for seeds, spores and broken fragments of plants to get from pond to pond, but there may be other means of transport. One of my favourite academic papers* from 2012 about pond ecology is a fine example featuring some rather larger means of dispersal. I know that ”favourite” is not the sort of criterion science is supposed to use in these days of research metrics and impact factors, but let’s leave those cold measures behind and head to the warmth of Africa. Bram Vanshoenwinkel and his colleagues at the University of Leuven in Belgium and in Harare in Zimbabwe knew that many of the large mammals in the African bush needed to drink regularly, moving from pond to pond, often wallowing and caking themselves in mud. What if that mud held seeds of plants or eggs and spores of invertebrates? The buffalo, antelope, warthogs and elephants would be a superb means to get from pond to pond. All you’d have to do to find out was scrape the mud off an elephant. On second thoughts, maybe not. Let the elephant do the scraping for you. So Bram and co collected mud from the trunks of trees from around temporary ponds in the Zimbabwean bush where animals had rubbed and scratched.
Mud was collected from as high as 400 cm up the tree trunks. The mud was then rewetted in the lab, incubated and any animals that hatched out or plants that germinated were identified. The mud spawned a host of different creatures, mostly various water fleas (Cladocera), pea shrimps (Ostraocda) and other more exotic crustaceans of temporary pools such as tadpole shrimps (Triops). Also a few plants including a duckweed (Lemna). Best of all was the spread of mud up and down the tree trunks; there was a distinct pattern with a lot of mud at around 300 cm (elephant scratch height), another clump at 120 cm (rhino and buffalo) and a third at ~60 cm (warthog height). There will be some of you reading this humming songs from the Lion King by now. It is a superb mental picture though, all that rubbing, itching, scratching, wallowing and glooping. Elephants at Druridge is unlikely but cattle, sheep and horses are there in numbers. It is a fair bet that they make effective vectors too. * Vanschoenwinkel, B. et al. (2012) Freshwater Biology, Vol. 56, pp 1606-1619

Saturday, 19 January 2013

Just how fast can pondweeds travel?

The pondweeds that turned up in the field ponds, discovered at the end of the harvest when the ponds were accessible after a summer behind the thickets of oil seed rape (Blog, 12th Jan), were unexpected. I should not be surprised: much of my work on ponds has been teetering along that tricky line trying to work out if the animals and plants are where they are because of some reliable rules, a response to measurable, describable influences such as nutrient levels in the water or the presence of a predator... or perhaps they are where they are just as accidents of history. I am reassured ponds remain full of surprises. Just how fast can plants arrive in a pond or wetland? My favourite example, albeit just a one off anecdote, is from Aberlady Bay, on the south coast of the Firth of Forth east of Edinburgh. In 1989 a pond was scraped out of the sandy wet grasslands, intended to encourage wading birds. You can see the raw sand of the pond on the day it was dug.
The following day I was back on the reserve and walked up to the pond to take some more photographs. In the shallows were conspicuous rafts of feathers, and, tangled in amongst the preening debris, stems and clumps of aquatic plants. Not plants that grew around the edge of the pond which had been dug out in the middle of a grass sward, but new plants, plants i could not recall growing on teh site at all. The plants seemed to have been carried in by birds within twenty four hours. By the summer of 1990 the scrape was choked with a glorious mess of aquatic plants and teeming with invertebrates, even though the sand sides remained exposed and bare. None of the plants had been introduced by the reserve team. That is how fast plants can travel.