Tuesday, 30 April 2013
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
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
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
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
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.