MSc Research with WTT

I’ve just had the pleasure of hosting two MSc students from Queen Mary University of London (co-supervised with Dr Chris Eizaguirre), partly for the WTT Annual Get Together, and partly to undertake some fieldwork specifically for Charlotte Pike’s project. I alluded to their research projects in a former post and now I have the pleasure of handing over to them to update you.

Charlotte’s project focuses on the use of stable isotopes to determine the success of river restoration. I will be analysing samples from pre and post intervention works against an unimpacted control site on the same river to see how the restoration has affected the architecture’ of the food web. Hopefully it should be more like the control! The intervention works have been carried out by the Ribble Rivers Trust at two locations; Bashall Brook and Towneley Hall. At Bashall Brook, a riparian zone has been created where banks of the river were previously bare; essentially livestock exclusion fencing now removes the impacts of grazing and poaching. This strip of vegetation acts as a buffer to reduce nutrient run-off from farmland, keeps the ground more stable and resilient to flood damage to reduce soil erosion, and provides necessary refuge for wildlife. At Towneley Hall, a partial weir removal and a rock pass re-instates the connectivity of the River Calder allowing fish to move between formerly fragmented habitats. These interventions have been conducted to improve the quality of the habitat at these two sites, and it’s my job to find out what changes have occurred as a result! 

Abbie’s project focuses on investigating the presence of some surprisingly large trout in areas of eastern England. These fish are suspected to be migratory sea-trout due to their large size comparative to other trout in the area. Identifying whether these individuals are in fact migrating to and from marine areas will be important in order to correctly manage migratory passages in these rivers. Making sure these areas are suitable for migration will also help support the input of these suspected populations to the wider sea-trout stocks.

Eel wrestling — definitiely a two-person job!

Just over a month in — and a lot of reading later – we are definitely feeling more confident with stable isotopes. In short, we are what we eat! When an organism consumes food, it gets integrated into its tissues, producing an isotope signal that we can measure. This signal can be used in a couple of different ways. In Charlotte’s project, it will be used as a proxy for trophic position, from which we can identify any changes at a population or community level in the river and see how organisms have reacted to the interventions. In Abbie’s project, we can use it to get an idea of habitat use across a salinity gradient. This means tracing where our fish are feeding and indicating whether they are resident brown or migratory sea trout. We hope to use fry samples to assess whether sea-trout are spawning in the area because the fry should have a similar isotope signal to their mother ie rather different from fry from parents resident in the river.

We began our journey with a helping hand from Tor Kemp, Jon’s PhD student at QM (and stable isotope whizz), who took the time to help us get to grips with some of the analyses and statistics we would be using in the future. She introduced us to R packages SIBER and MIX-SIAR, so we should be able to analyse our data appropriately — we are extremely grateful!

Grinding (using a v flash agate pestle and mortar) and weighing miniscule samples for mass spectrometry

Over the last month, sample processing has begun including fish dissections and invertebrate preparation. The inverts with calcium carbonate shells had to be separated from those shells to prevent the inorganic carbon affecting the results; some of the fiddly specimens will require acid treatment to remove the smaller parts of shell. Once this has all been carried out, the samples get put into the oven for a few days to dry out. Next steps entail grinding and then weighing on a micro balance (we are routinely weighing out less than 1 microgram!) ready for analysis on the Mass Spectrometer. Sounds easy enough on paper, but this is actually a slow process. However, Abbie is starting to get some results through and we are both looking forward to the coming weeks where we should start to be able to piece together more of a picture! Needless to say, we’re looking forward to the field work!

Download a copy of the poster we presented at the WTT Annual Get Together, here.

Follow our endeavours via @Charlotte_Pike1 & @AbbieNye