Just a very quick little post to keep the blog up to date on all the goings on.
Firstly, the titles of the blogs do not actually represent my current PhD timeline. I am currently almost 8 months down and just about to organise my first Progress Panel in which the academics around the department listen to what I’ve done / plan to do and either “tell me to pull my finger out”, “good job” or “ok, so you have done it all this way, but shouldn’t you have done it like this?”
SO the last couple of months on Christmas Island was taken up with sampling the snail community based on the study design of the last post. This co-in sided with the Parks Australia team conducting their Island Wide Survey for the yellow crazy ant so as a result I was able to ad another supercolony to the study (as they found a few more raging bad-boys that I hadn’t stumbled across in my travels). I then subsequently located another site for each of the other treatments, thereby, taking my replication up to n = 5. Not spectacular but it does look a hell of a lot better and will increase the confidence in my results. Sampling the 20 sites took the best part of 6 weeks as (without getting into the nitty gritty of the methods) it took at least a day to sample a single site. This involved timed-searches of the understorey – in which I sampled 100 m2 for 2 h – and the collection of litter samples (eight 25 x 25 cm) that then had the snails sieved, then floated, then picked out of the soil. By the time that was all finished, and I’d done some point transects to quantify understorey complexity, I only had less than a week on the island so I really only had time to pack up my thing, cruise around the island in a boat and sink a few more beers.
Anyway… in the last two months I have been spending everyday at uni with my primary task being the counting and identifying of the snails that I collected (which as you can image got very tedious and annoying pretty quickly so I also filled my time up with writing various manuscripts that are in the in prep stage and other general invasion / snail research). One the general snail research side of things I would highly recommend a little, very zen book called The sound of a wild snail eating (cheers to Thea for the present) in which the author, while bed-ridden with a debilitating illness, keeps herself sane by keeping and making observations of a common forest snail – quite a good read if your willing yourself to be slightly interested in snails.
SO the good news is that after 6 weeks of staring down a microscope I have finished the initial count of my snails. I say ‘initial’ because there are a handful of things that I haven’t identified properly that I have to go back to. I spent the first week shooting off emails to one of Australia’s leading malacologists to get the heads up on the distinguishing characters between some closely related species, but the individuals that I haven’t identified are either juveniles or new species to the island so I’ll fix that up later. So after identifying 20 species from 7,628 individuals I now have some preliminary results.
Without giving too much away (because when I say preliminary results I do really mean preliminary!) it appears that the ant-scale mutualism, and the subsequent changes in forest structure has:
i) resulted in an up to four-fold increase in snail abundance – facilitating increased numbers of both exotic and native snails.
ii) altered snail community composition through the entry of snail species that were absent from intact forest (secondary invasion au-go-go!)
iii) most likely had little to no effect on species richness, but
iv) probably decreased snail diversity, as although there are loads more snails where the primary invasion has had an effect, from eye-balling the data it looks like only 2 or 3 species are in super-high numbers at those sites, with the rest present in abundances similar to intact sites (which appear to be more even).
I think we’ll leave it at that. This has successfully killed the last hour and half whereby I didn’t wish to continue putting that literature review together. The next post should probably contain some numbers rather than just impressions from data eye-balling so stay tuned