Tessera

ERC REFRESH programme

@ercrefresh.bsky.social

Investigating the biological role of dissolved organic matter in freshwater ecosystems. Isotopes, omics, molecular biology, carbon, nitrogen and phosphorus. 🧪💦🌿🐟🐌

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James McDonald @jameslmcdonald.bsky.social · last yr.

Great to have the first set of experiments complete for the @ercrefresh.bsky.social project! Eight days in a beautiful chalk stream studying the role of DOM in freshwater systems as part of a @ukri.org and @erc.europa.eu funded programme.

Experimental microcosms placed inside a stream. Custom made frames hold them in place, whilst the sampling team extract samples and process in the area situated opposite.

Microcosms in situ. Each jar is fitted with a motorised lid fitted with a paddle to stir the water. Fiddly but very rewarding when in synchrony!

Penny Johnes @pennyjohnes.bsky.social · 12mo ago

That's a wrap on our @erc.europa.eu @ukri.org @ercrefresh.bsky.social programme 2nd expt.. A very different environment than the chalk stream in our 1st expt. but nonetheless with wonderful biota: Beautiful Demoiselle damselflies fluttering around us, and freshwater limpets grazing our biofilms! 🧪

Male Beautiful Demoiselle damselfly, abundant at our clay stream site in SW England.

Female Beautiful Demoiselle damselfly at our site.

These damselflies frequently landed on us and our equipment as we worked.

We found several of these small, native freshwater limpets on our biofilm slides when we extracted them. Ancylus fluvialitis.

ERC REFRESH programme @ercrefresh.bsky.social · 11mo ago

Fantastic field season with the team. Looking forward to sample and data analyses over the winter, then planning for our 2026 field campaign on the back of those findings!

Penny Johnes@pennyjohnes.bsky.social · 11mo ago

And that's the final @erc.europa.eu @ercrefresh.bsky.social stream isotope experiment of our 2025 field season complete. With many thanks to @bristoluni.bsky.social PhD students Matt McCormack and Boyi Li for their help with eDNA sampling and completing site decommissioning before the rain arrived 🧪

James McDonald snd Matt McCormack extracting mesocosms from frames

ERC REFRESH programme @ercrefresh.bsky.social · last yr.

Come and join us. We're already underway with major experiments throughout the summer. Huge opportunity for the right candidate! See link for details. 🧪

Penny Johnes@pennyjohnes.bsky.social · last yr.

‪Great opportunity: full @ukri.org funded PhD Studentship with 4 years fees, stipend (£19237 pa) and full Research Training Support Grant, working with Prof Ian Bull, Director of the National Environmental Isotope Facility and my @ercrefresh.bsky.social team! Starts 10/2025 shorturl.at/AJREj 🧪

An algal bloom on a nutrient enriched lake encroaches into the Nymphaea alba and Chara hispida beds, causing plant dieback. Your work will develop a novel, targeted analytical method to allow us to rapidly screen samples to determine the molecular composition of the dissolved organic nutrients in these and other waters. These provide a critically important but overlooked nutrient resource driving ecosystem damage and biodiversity decline in waterbodies. We currently lack a unified technique that can rapidly screen samples in a targeted manner. You'll likely be highly motivated, enjoy both field and laboratory work, and be a good analytical chemist with attention to detail who is keen to make your mark through novel method development. Give Ian a ring or send him an e.mail (ian.d.bull@bristol.ac.uk), or contact me here or via my e.mail penny.johnes@bristol.ac.uk. We have a large team on the ERC REFRESH programme that you will be joining, along with two other PhD students due to start at the same time. Great team and learning opportunities.

ERC REFRESH programme @ercrefresh.bsky.social · last yr.

Four time points out of 6 completed in our first experiment (chalk stream) and it's all going well. Next stop is deployment of the biofilm frames in our clay stream to develop biofilms for experiment 2 in 3 weeks time. Great help from @sydneyenns.bsky.social from our @ukri.org QUANTUM team. 🧪

PI setting up for 48 h sampling at our chalk stream site.

Dr Charlotte Briddon transferring our biofilm frames to our clay stream site to start incubation. Each frame holds 45 glass slides, and we need c. 450 for each experiment.

@jameslmcdonald.bsky.social from ERC REFRESH and @sydneyenns.bsky.social from NERC QUANTUM deploying the frames in a sunny part of the stream.

A biofilm coated slide at 48 h sampling time point.

ERC REFRESH programme @ercrefresh.bsky.social · last yr.

Follow the team @ercrefresh.bsky.social as we investigate controls on rates & pathways of DOM uptake into stream foodwebs. This week we ran the first of 3 experiments exploring if environmental character, warming or velocity affect uptake this week. Chalk stream first, then clay stream, then peat! 🧪

Meet the team! Drs Charlotte Briddon and @jameslmcdonald.bsky.social, working on setting up the motors to drive the paddles in our warming (bubble wrap jackets, elevated higher in the water column) and warming plus high (double the rpm) flow velocity experiment. Further along, Dr @acastrocastellon.bsky.social from our @ukri.org NERC QUANTUM programme is setting up the jars for our ambient temperature with stirring experiment in this classic chalk stream. The catchment comprises calcium carbonate rich chalk, flows to the river are dominated by groundwater and deeper throughflow, and the stream ecosystem supports Ranunculus spp. (water crowfoot), Callitriche spp. (starwort) and Rorippa nasturtium-aquaticum (watercress) along with a native brown trout population. How will biotic response rates to isotope dosing of 13C15N labelled compounds in this alkaline, and gin-clear stream contrast with those in a more turbid clay stream (experiment 2) and dystrophic peatland stream (experiment 3). We look forward to finding out!

Each jar contains biofilms cultivated in the stream prior to each experiment, and mosses (Fontinalis antipyretica) which are ubiquitous in UK rivers and streams. Their lack of rooting structure makes them ideal for these isotope dosing experiments. Later on in the programme we will introduce benthic chambers and endemic higher plants, but these 6L mesocosms are too small to accommodate them.