Garden earthworm bothering part 2: identification

So how do you go about identifying an earthworm? Firstly in most cases your earthworm needs to be an adult, mature earthworms have a saddle (clitellum) which is part of the reproductive system – forming a cocoon which protects the earthworm’s eggs. Unfortunately only five of the earthworms collected from my garden survey were adults so the rest went back into the garden unidentified.



There are 27 species of earthworm in the UK, some of which, like the Eisenia fetida I found in the compost heap, can be identified in the field, for these you can use the free OPAL Earthworm Guide or online key but others require close examination using a microscope and an identification key. The ‘bible’ for UK earthworm identification is Sims and Gerard (1999) but as Father Christmas was not kind enough to bring me a copy I used Sherlock (2012). This key is published by the Field Studies Council and is part of their excellent AIDGAP (Aid to Identification in Difficult Groups of Animals and Plants) series, it is a perfect step up from the OPAL guide and I highly recommend it - if you join the Earthworm Society of Britain you will receive a copy in their recording pack.

Earthworm underside showing some features used in earthworm identification

By now I have seen a fair few earthworms so I was reasonably confident without using a key that my two from the soil pits were in the genus Lumbricus, these tend to be dark in colour and often iridescent, but it is good practice to check. In the FSC key Lumbricus and one other genus are separated in the first couplet by the structure of their head. At the head of the worm is a fleshly lobe or prostomium which covers the mouth, in some worms two lines run from the prostomium so from the top it looks like the first segment is split into three, this is known as a tanylobic head and is the type found in Lumbricus (the other type is called epilobic).

Top view of earthworm head and clitellum (note the iridescence)

The next step is to count the number of segments before the clitellum and how many segments the clitellum covers. This can be quite tricky and I find it particularly difficult on the clitellum were the segments are not as distinct. Unfortunately this was the case with my two specimens so for now I will have to leave them at Lumbricus sp. until an expert at the museum can help me with them, such is the way with identification, especially when you are learning, but with my perfectionist nature I still find this hard to deal with.

Thankfully my confidence was restored by being able to identify the two species I found underneath my log pile, these were both epilobic worms.

Aporrectodea caliginosa showing epilobic type head

Other characters used in earthworm identification are the position and shape of the tubercula pubertatis (TP for short) which are a pair of raised pads on the side of the clitellum, both my worms from the log pile had distinctively shaped TPs which I recognised from earthworms identified during my MSc project. The larger pale specimen had two bumps on segments 31 and 33 so I recognised it as Aporrectodea caliginosa, one of the most common UK earthworms. The bumps can sometimes be so prominent they can be seen without a microscope.

The distinctive two bumps forming the TP of Aporrectodea caliginosa

The other two worms were much smaller and dark red in colour with a crescent shaped bump on the TP which I recognised as belonging to Satchellius mammalis, the 5th commonest species I found in my MSc study site.

The crescent-shaped bump on the TP of Satchellius mammalis

So with just an hour in the garden and I already have 4 or 5 earthworm species ready to submit to the Earthworm Recording Scheme. Why not have a go yourself? For such an ecological important group earthworms are terribly under-recorded and with just a small number of species with good identification keys and reasonably clear identification features they are a nice group to 'do'.

Garden earthworm bothering part 1: sampling

I have sulking at home since the Soil Biodiversity Group earthworm fieldwork ended so between Christmas and the New Year I decided to get out into the garden and hunt for earthworms - one of the great things about earthworms is that they are active even during winter so long as the ground is not frozen. There was some difficulty in that my sister had borrowed the spade so I had to make do with a fork and trowel, not ideal for making neat soil pits. Also, my ‘assistant’ who was curious to what I had been up to in fields these past weeks turned up without his warm clothes and waterproofs so it ended up being a rather brief survey which I will continue in the New Year.

Andrew, my somewhat reluctant ‘assistant’ Quote: “You did this all day in a field!? Would drive me round the bend”

But despite this I did let him pour the mustard solution

I used the standard method for earthworm surveys, details of which can be found on the Earthworm Society of Britain website. The first pit was dug in the scruffy bit of grass that passes for a lawn and I was surprised to find the soil was drier, less clayey and less compacted than I expected. It was also without structure, no layers of top soil and subsoil like I have been used to in the fields and woodland, just loose soil on top a layer of rubble – sadly typical of suburban soils - but there were still earthworms. Sadly the mustard solution did not produce any earthworms although I was not surprised as the soil is rather shallow and I have not seen many of the distinctive casts the anecic types make.

An earthworm in its burrow in the soil removed from the lawn

Sadly the mustard solution did not produce any anecic earthworms although I was not surprised as the soil is rather shallow and I have not seen many of the distinctive casts they make on the lawn.The next pit was made in one of the raised vegetable beds and even this highly disturbed area produced five earthworms, although unfortunately all immature specimens which could not be identified to species. As we were losing daylight and Andrew was getting cold we had a quick look in some microhabitats rather than start another soil pit. As expected the compost heap produced lots of the Compost or Brandling Worm Eisenia fetida which lives in areas of high organic matter, it has a stripy appearance when moving and they exuded a unpleasant yellow fluid when handled.

A handful of Eisenia fetida

Under my log pile I found two small red worms and a larger pale pink one which along with the two adult earthworms from the soils pits were retained for identification. In part two I will go through the steps in identifying these earthworms.

Earthworms – the final chapter!

 

With the soil analysis laboratory in York shortly closing for Christmas the race was on to complete enough samples in each field and county for the statistician on the project to work his magic. The result was an epic 400 mile round trip to finish off sampling fields in Leicestershire, Berkshire and Dorset. It was just David and I who set off Sunday evening for Leicester, meaning that I was navigator (oh the pressure!), but on Monday we met up with Jo who is the technician at the University of York undertaking the soil analysis, to finish the final field in Loddington.

Jo and David sorting soil (is David praying for the project to end?)

It was great to meet with Jo and find out about the soil analysis side of the project, at the moment she is working on the samples taken for the measurement of microbial activity since these need to be processed quickly for accurate results, later analysis will be done on particle size, pH, nutrient content and more. The method used by the lab is the fluorescein-diacetate (FDA) hydrolysis assay, enzyme activity from microbes in the soil sample cause the colourless FDA to break down into fluorescein which is a fluorescent yellow-green. The intensity of the colour is measured using spectroscopy and comparison with a standard determines the relative microbial activity of the sample.

Not unlike the earthworms Jo has found the microbial activity to vary greatly both between and within fields, from extremely high in the field in Yorkshire with the longhorn cattle to nearly ‘dead’ in one of the fields in Berkshire. Jo informed me that clayey soils are particularly difficult to process which I could sympathise with as they are also difficult to sort!

We made good progress despite being just the three of us, squeezing in an extra 11th sample which unfortunately had to be sorted in car headlights (again) and I made the tactical error of not taking my waterproofs off so ended up being volunteered to wander around a field in the dark to put the soil back in the hole.

Such dedication!

Loddington finished, Jo returned to York with the soil samples and David and I travelled south to Berkshire, returning to the lovely Dundas Arms, sadly too late for dinner but they did make us some amazing sandwiches. In the morning we were joined by Paul and Kelly and volunteers Cecilia and Alex, as a team of six we made brilliant progress and a super 21 samples were completed.

Kelly and David take the environmental variables while Cecilia prepares to sort

The Soil Biodiversity Group gets stuck into sorting another sample

With still a few left to do in Berkshire next week the rest of the team went their separate ways while David and I travelled to Dorset. Thankfully this time we arrived in time for a pub dinner, nothing like two days of sandwiches for dinner to make me appreciate a hot meal! The next morning we met with the farmer of the final farm to find out about the management history of the fields and decide which would be suitable for the project. After picking up Paul from the train station we began sampling the penultimate field of the project.

The penultimate field, the barn at the back would prove useful later in the week!

On Thursday we were joined by fellow project veterans Sholto and Irfaan to finish off the field in the quarry (no blasting this week sadly) and the other two fields. By Friday the weather was against us, but we maximised the work achieved by sorting in the barn during the heaviest rain and by dusk the required samples had been done!

A very wet and muddy Sholto, Irfaan and Paul sorting in the rain in Dorset

All that remained was to finish the two fields in Berkshire so on Monday David, Paul and I met up again for the final day of sampling, two weeks and a day overdue! The fields were extremely wet, particularly (and not surprisingly) the one by the river, with one soil moisture reading at 100%. In the absence of a tap the stream proved useful for filling the mustard bottles, since they were to be used straight away the issue of bacterial contamination was avoided.

In the absence of a hotel or research centre to fill the mustard bottles, a stream will do

 

And now…

The final pit

And so finally the time had come, after 10 weeks of field work, the final pit was dug!

At last – the final pit!

And Paul had the ‘honour’ of pouring the final bottle of mustard solution

Of course the project is not over, there are still thousands of earthworms to count and identify, soil samples to analyse, numbers to crunch, meetings to attend and papers to write, but my part is done. It has been a fantastic experience for me to be part of such an ambitious project. Being involved has given me a greater understanding of what is involved in research,  including the logistical and political aspects as well as the science. I have been reminded how much I enjoy field work, even in the rain and mud but most of all I reaffirmed my aspiration to be a researcher. I miss being in a muddy field but most of all I miss the interaction with like-minded people (wow, never thought I would say that!) – from discussion on scientific topics to intense debate on the merits of different biscuits. The New Year should bring more financial stability after my student life and so I hope to be able to visit the Museum once a week and continue volunteering with the Soil Biodiversity Group.

And so I offer a big thank you to everyone I worked with on the project, you have been an inspiration.

More earthworm sampling, or the mystery of the farty mustard

Another county, another field… Last Monday and Tuesday I was again away with the Natural History Museum Soil Biodiversity Group, this time heading up to Leicestershire, for more earthworm sampling. Not as scenic as Somerset, we were sampling in a research farm near Loddington, in addition to myself, Sholto was again volunteering, I also met for the first time Salma and we were joined by Irfaan on Tuesday.

Another earthworm is sampled by Irfaan, with Salma and Sholto

Salma is trained in the correct way to retract the tape measure

In the previous week there was a problem with the mustard solution, which had developed a pungent smell of hydrogen sulphide (egg-fart gas). This was a concern because the smell was so strong it could be killing the worms in their burrows before they could emerge. Could the change be because of a faulty batch of mustard powder, or change to the ingredients? This week different batch numbers of mustard powder were purchased to test this.

David checks the bouquet of the mustard solution

Sniffing the mustard solution before pouring was now a necessary step, after the first mixing the smell was promising but by the morning some bottles had deteriorated. A new hypothesis was proposed that some sort of bacterial contamination was causing the smell and then it was realised the problem started after the mustard solution was made up using water from the soil laboratory back at the the Museum. The water in the labs comes from the museum’s own borehole and often has a slightly sulphurous smell, could some sulphur-reducing bacteria dwelling in the supply have caused the problem? It was decided to use fresh water bottles on the next trip.

Tuesday evening we travelled back to London and on Wednesday I spent the afternoon helping in the soil laboratory preparing the kit for Thursday and Friday and changing the alcohol in the earthworm samples. Earthworms have a high water content and this dilutes the alcohol, if the liquid is not replaced with fresh spirit the earthworms can start  to decompose which makes identification difficult (and stinky). Then Wednesday evening we left for Dorset - the final county being sampled in.

That’s a lot of earthworms!

Living in just the next county I have had many family holidays in Dorset and it was a pleasure to be back in beautiful Purbeck. Our site was near a quarry were limestone (Purbeck ‘marble’) is extracted and on Friday we got to view a blasting, which was very exciting.

Quarry manager Simon discusses the site with David

Quarry blasting (guess who made the excited squeal!)

The shallow soil did not yield many big anecic worms but large numbers of smaller species, since earthworms have a preference for areas of high pH. As might be expected there were also large numbers of snail shells which I tried my best not to be distracted by, although I think I may sneak a few specimens when we return next week!

Off for a well-earned meal after a hard day’s earthworm sampling

My first symposium

 

On the 28th and 29th November I attended the British Ecological Society Moving on to a PhD and Mastering Ecology Symposium, for advice on PhDs and the opportunity to present my Masters research. This was the first Symposium I have presented at and although I had to give a presentation of my work during my MSc this was to a much larger group of people I had not met before. I was very anxious, with one half of me saying “why are you putting yourself through this?” and the other half “it’s good for you and will get easier the more you do it”. Thankfully fellow Soil Biodiversity Group volunteer Fez was also at the Symposium presenting a poster of her work on termites in Wallacea which was a confidence boost.

Fez and I with our Soil Biodiversity Group posters at the British Ecological Society Mastering Ecology Symposium

The talk was both the fastest and slowest five minutes of my life! It went by in a blur. Feedback however was not too bad, considering how scared I was, hopefully next time it will get better and maybe one day I will be as confident as my university lecturers etc.

More earthworm bothering

For eight days in November I returned for more earthworm survey work with the Natural History Museum Soil Biodiversity Group, this time in Somerset and Berkshire. A small team of volunteers this time, just myself and long-time SBG volunteer Irfaan, travelled first to the Somerset site to continue work started the previous week. We had been informed the Somerset site was the most beautiful yet but when we arrived on Monday the fog was so thick we had to take David’s word for it! Thankfully, by Tuesday the sun had returned to reveal a superb landscape, the countryside you imagine from hundreds of years ago, with little patchwork fields fringed with ancient hedgerows.

What a difference a day makes in Somerset

Four fields are sampled per farm, covering a spectrum of management intensity, such as how often the field is grazed, how much fertiliser (animal or artificial) is added and whether it has been ploughed or used for crops in the past. The field we worked first was the lowest intensity field at the Somerset site, not surprisingly as it was some distance from the nearest track, was steep and had springs running through it. This field had never been ploughed, giving an odd feeling of being possibly the first people to disturb the soil. It also had the biggest Yellow Meadow Ant (Lasius flavus) mounds I have ever seen!

Horse battered Yellow Meadow Ant (Lasius flavus) mound, at least two foot tall

Digging and coring in Somerset, quite possibly the first time the soil has been broken by man!

For a change from sheep and cows the fields at the Somerset site were grazed by Shire Horses which noised around us and the kit expecting food and generally being a distraction, having to be chased away at intervals. As handsome as the Shires were, I was more excited and distracted by the lovely Noon Flies (Mesembrina meridiana).

Shire Horses in Somerset

Dipterological distraction: Noon Fly (Mesembrina meridiana) in Somerset (thanks to Georgie for this photograph from the previous week's visit)

Within each field a bare minimum of 18, preferably 20, samples are made. Half of these are located at random using a combination of a randomly chosen direction and distance. The direction is decided using a super scientific method of David spinning around.

If he had fallen over I could have bagged £300 pounds!

It is double blind so that some else who is not watching calls out when to stop, although this sometimes has to be done a couple of times if the random direction is in an unsuitable place, such as too close to the edge of the field or trees which may have different micro-environment to the rest of the field. The distance from the previous pit to the next is then determined by a random number table. The rest of the samples are coverage pits which are spread out over the field.

Once the location is marked with a flag it’s time to start over again taking measurements, digging a pit, taking samples and hunting for worms!

Irfaan and I intently sorting soil for worms

There’s one!

On this trip we came across one of my favourite species of earthworm, the Blue-grey worm (Octolasion cyaneum), this is the UK’s largest species of pale earthworm and is often a pretty bluish colour, with a yellow tail, but we did not get many of the big anecic earthworms that emerge after the mustard solution is added.

Blue-grey worm (Octolasion cyaneum)

On Thursday we left Somerset for Berkshire, unfortunately still with a field left to finish. The site in Berkshire was the Organic Research Centre Elm Farm.



Excitingly the very first pit had a bumper crop of the UK’s largest earthworm - Lumbricus terrestris emerge when the mustard solution was added, some were bigger than by baby snakes at home! Could this be because of higher organic inputs in this field than Somerset? The statistics will tell us in time (hopefully!).

Lumbricus terrestris expelled by mustard solution

Oh and yes the mustard solution is often made up in our hotel rooms, if your next stay has a whiff of Colman’s, maybe the SBG have been there!

Fungi in Shropshire

This weekend saw a return visit to FSC Preston Montford for my final course in the University Certificate in Biological Recording and Species Identification - Identification of Macrofungi tutored by Irene Ridge. An interest in fungi (or mycology) was one of my earliest, after attending a fungi foray at Queen Elizabeth Country Park, Hampshire, with the RSPB’s Phoenix group way back in 1996. This led me to purchase a compound microscope in 2000 but I found it difficult to master the techniques needed to prepare slides without tuition and soon moved on to other groups, hence my motivation to attend this course and have another go.

After an introduction to fungi and how to record and describe specimens on the Friday evening it was off to Attingham Park on Saturday to collect our own specimens.




This site introduced me to grassland fungi, a habitat which I had not forayed before. The short, old lawns around Attingham Hall are an example of waxcap-grassland, a fungal community characterised by waxcaps (Hygrocybe spp.), club fungi (Clavariaceae) pink-gills (Entoloma spp.) and earthtongues (Geoglossaceae). Waxcap-grasslands are of conservation interest as indicators of unimproved grassland, a threatened habitat in the UK. It is only recently they have begun to receive attention on their ecology and distribution, with a English Nature Report published in 2003.

Snowy Waxcap Hygrocybe virginea

Apricot Club Clavulinopsis luteo-alba

Attingham is not all grassland though, there were many handsome mature trees in which we found some woodland fungi which were familiar to me. Irene explained the importance of taking good field notes when collecting fungi, many are mycorrhizal, a symbiotic relationship with plants, and some fungi species are restricted to certain tree species; without this information identification may not be possible. Whether the fungus was growing alone or in groups, was attached to wood or soil, and even the smell, colour and texture of the cap which may change after collection can be important for identification and must be noted on collection.

Artist’s Bracket Ganoderma sp. (probably G. applanatum) on Beech

A jelly-fungus, Exidea nucleolus

Irene discusses the identification features of a Boletus fungus

Back in the lab we began identifying our collections using a mixture of identification books and keys. I began by making spore prints as the colour of the spores is a key feature in identification, in the past I had done this by cutting the cap off and putting it on white and black paper but Irene demonstrated suspending the fruit body over a microscope slide in a cup. This keeps the specimen moist, as spores do not drop when the atmosphere is dry, explaining why I was not very successful with mine in the past!



On the Sunday we were off on another trip, this time to woodland at Nesscliffe Country Park.

Beech woodland at Nesscliffe – lots of lovely leaf litter!

Russula ochroleuca

Russula is one of my favourite fungi, they generally have a typical mushroom shape, crumbly flesh and gills (their common name is brittlegill). There are many species, often with brightly coloured caps like the yellow Russula ochrolecua we found in numbers at Nesscliffe, this is very common species which grows with many species of trees, but other Russula form mycorrhiza with specific trees and are one of the groups were good field notes are important. They are also identified by differences in cap and spore colour, ideally using a colour card as this can be subjective. Taste can also be important, which is checked by chewing a small piece which is then spat out, some have a very hot taste. This multisensory aspect of fungi identification is part of the appeal for me although the subjective nature of colour, smell and taste can be a problem, with some books describing species as smelling of obscure things as ‘Russian leather’ and ‘old laundry soap’!

Jelly Ear Auricularia auricula-judae

Also at Nesscliffe I found a branch covered with wonderful Jelly Ear (Auricularia auricula-judae) one of my favourite fungi as it looks so much like an ear. I also found a tiny jelly fungus growing on beech mast while I was searching (unsuccessfully) for the beechmast fungus Xylaria carpophila. Another highlight was the Wood Woollyfoot (Gymnopus peronatus) which as the common name suggests has a lovely ‘woolly’ base to the stipe.

Wood Woollyfoot (Gymnopus peronatus) in habitat and close up in the lab showing woolly base to stipe

Another old favourite is “smell it before you see it” Stinkhorn (Phallus impudicus) although we only found in the ‘egg’ stage and one old specimen, both badly eaten by slugs, missing out on in its erect magnificence.

Stinkhorn (Phallus impudicus) ‘egg’

Back in the lab Irene gave a demonstration of microscopy techniques for fungi and I had a go myself, finally seeing the spores, basidia and cystidia which I had failed to find on my own. These preparations involve taking a small piece of gill, putting a drop on a stain called Congo Red on top and then squashing a coverslip gently over the top. After blotting any excess liquid the slide is examined under a high power microscope. I was hoping to show some of my own slides but unfortunately I don’t have any Congo Red at home so the photomicrographs below are courtesy of Wikipedia Commons.

Basidia stained with Congo Red, the pointy bits on top are where the spores attach By Andreas Kunze (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons)

Basidia (singular basidium) are the spore bearing structures in one of the major groups of fungi, the Basidiomycota which includes most of the species identified this weekend; the shape and number of spores is used in identification. Cystidia are sticky-outy cells found on various parts of the fungal fruit body, and the position, shape and reaction with certain chemicals are important for identification.

Cystidia By Andreas Kunze (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons)

The course finished with an assignment – identifying 15 specimens and/or photographs, it was strange to think it was my last on the course and that with my uCert and MSc complete I am for the first time in 7 years not in formal education! The two fungi forays and tuition in microscopy techniques were just what I needed to get back into fungi identification, I will be dusting off my old compound microscope and giving it another go!