Earthworms by numbers

Last week I finished sorting and identifying ‘my’ half of the Soil Biodiversity Group’s samples from the BESS Earthworm Project. The tubes from the last couple of fields were rather full, and because earthworms contain a high percentage of water this had diluted the alcohol, reducing its preserving qualities. The liquid in the samples was dark and pungent and the earthworms soft, this made identification more difficult as the features can be obscured and the earthworms fragile to manipulate. The final earthworm I identified from the samples was a somewhat underwhelming, squishy, headless and tailless Aporrectodea longa!

The final tube was a particularly ‘squishy’ sample

Some previous samples were more exciting however, in particular during the project I have identified by first ever Ap. limicola, Ap. caliginosa subsp. noctura and Octolasion tyrtaeum, although sadly I did not meet the Ap. icterica I was also hoping to find. Here are some of the facts and figures from my time volunteering on the BESS earthworm project:

Sorting and identifying earthworms from 14 fields from seven farms took around 90 hours, and I counted a total of 5940 earthworm specimens, 2124 which could be identified to species. I identified 16 earthworm taxa in total, with the highest number (12) occurring at the Dorset site. This was also the site with the highest number of earthworms per single pit – a whopping 110 individuals, but the highest number of species per pit was from the Dumfries and Galloway site, with seven.

The most common species in my samples were, as expected, Aporrectodea caliginosa (742) and Allolobophora chlorotica (506), but the sites differed in abundance between the two and it will be interesting to see if any environmental preferences emerge when the whole dataset in analysed. The rarest earthworms in my half of the data are Ap. caliginosa subsp. nocturna and Octolasion tyrtaeum with just a single specimen each, both from the fields in Dorset. Other uncommon species were Satchellius mammalis (4) and Dendrodrilus rubidus (3) both more commonly found in leaf litter, which is sparse in pasture.

Subjectively each field and farm had a different ‘character’ of earthworm diversity, and I am particularly looking forward to seeing what the statistics have to say about the variation between and within the different sites. Some preferences are quite obvious, Ap. limicola was found in large quantities exclusively (so far at least) from a field on a floodplain, and is known to have a preference for wet conditions (as suggested by its name, limnic = referring to freshwater). An old favourite of mine from my MSc project, Murchieona muldali, previously associated with hedgerows and field edges did seem to occur more frequently in low intensity fields with some scrub. There are so many other questions about earthworm diversity that the project will go some way to answering, like does earthworm diversity decrease with latitude? What are the environmental tolerances of each species and is there evidence for competitive exclusion? Do more fertile pastures have more individuals but fewer species? I am so excited to see the results!

Blog neglection excuses

 

I've been neglecting my blog again, tsh! There has been lots of exciting news in my life lately, but this has also accompanied by stress, and with so much on my mind I have not had the will to write.

Firstly I had the fantastic news that I was offered a place on the PhD I was interviewed for as the first choice candidate declined in favour of another offer. I accepted with little hesitation! The project title is Statistical modelling of how soil biodiversity and ecosystem function respond to human impacts in UK ecosystems, hosted at the Imperial College London Grantham Institute for Climate Change and working with the research groups PREDICTS and Soil Biodiversity Group at the Natural History Museum. This will use the huge unpublished datasets from the SBG to model how soil invertebrates respond to human impacts including climate change but there will be also be opportunities to collect new data - which will hopefully include some soil diptera larvae studies!

Secondly I accepted a job offer at Reading University which I began nearly a month ago. This is working as a field assistant at CAER with PhD student Chloe Hardman. She is researching biodiversity on farms using different agro-environment schemes, were farmers are paid for various activities which are supposed to increase biodiversity. Specifically I am helping with research on pollen and nectar sources on farms (i.e. flowers!) and pollinators. This involves fieldwork walking transects in different habitats across 12 farms in Southern England, recording bees, hoverflies and plants. It is wonderful to be making a living doing fieldwork identification skills after years of working inside an office! Together with my PhD offer I still can't quite believe how well my academic life is going at the moment, and keep thinking I will wake up from a dream!

My working conditions have improved greatly!

This Wednesday was my MSc graduation ceremony, I felt a little decadent going to another after my BSc one but the venue was the Royal Albert Hall in London so I couldn't pass up an opportunity to go there. My parents attended too so we decided to make a day of it, using the complimentary tickets I receive from volunteering at the Natural History Museum to visit the butterfly exhibition. It was fortuitous that the same day Paul was giving a Nature Live talk on the NERC BESS earthworm project which I have been volunteering on, which I dragged my parents along to see. Today I finished 'my' half of the samples and just in time as I will soon be returning to my MSc study site on the Isle of Wight to carry out more research there.

It’s going to be busy summer (indeed a busy four years are ahead!)