Penny Johnes
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pennyjohnes.bsky.social
Penny Johnes
@pennyjohnes.bsky.social
870 followers 550 following 260 posts
Professor of Biogeochemistry, UBris. Researches freshwater nutrient pollution and biodiversity loss in lakes, rivers and wetlands, and mitigation strategies. Nitrogen, phosphorus, carbon, isotopes, dissolved organic matter.

ORCiD: 0000-0003-1605-6896
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Reposted by Penny Johnes
mattmccormack1.bsky.social
Excited to start my PhD at @bristoluni.bsky.social as part of the @ercrefresh.bsky.social project under Penny Johnes, Dan Read (UKCEH) and Martin Genner!

I'll be exploring how key microorganisms utilise and transform dissolved organic matter. Looking forward to starting with the team next week!
Helping the team with mesocosm dosing experiments this summer. Native aquatic snails added to mesocosms to investigate the uptake of DOM. Learning about the experimental setup from James McDonald.
September 15, 2025 at 3:34 PM
pennyjohnes.bsky.social
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 Native aquatic snails collected 4 days after introduction to jars with 15N13C labelled biofilms and bryophytes. Matt and Boyi transferring heated mesocosms to the bank for eDNA and eRNA extraction, led by Martin Genner Leave no trace! Site returned to its original state after decommissioning. With many thanks to Bannau Brycheiniog National Park Authority for permission to work on the land.
August 27, 2025 at 10:46 AM
pennyjohnes.bsky.social
All fieldwork is now complete on our ukri.org @quantumfreshwaters.bsky.social project including sampling in 60 UK livestock farming headwater streams. We now focus on sample and data analyses, while we build models to test the likely efficacy of mitigation efforts to reduce impacts on UK rivers 🧪
Ayrshire X cattle in Scotland with direct access to a headwater stream. Cattle having direct access to streams causes significant increase in water pollution risk. Dairy Holstein Friesian herd in Wales, outdoor grazed. Sheep typically have direct access to watercourses too. They too can markedly increase pollution in headwater streams.
August 23, 2025 at 12:15 PM
pennyjohnes.bsky.social
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.
August 6, 2025 at 8:38 AM
pennyjohnes.bsky.social
Our @ukri.org funded @erc.europa.eu REFRESH programme is going well! Chalk stream isotope dosing expt. complete, clay expt. nearly complete with help from our first PhD student, @durham-university.bsky.social graduate Matt McCormack. Peat expt. set-up now underway @bannaubrycheiniog.bsky.social 🧪🐟🌿🐌
Charlotte Briddon and Sydney Enns working on the ambient treatment mesocosms in our clay stream experiment. Sydney Enns wearing her chest waders. These neoprene waders are warm and keep us dry (mostly, as long as we avoid barbed wire punctures) but we do get buoyant feet when we sit down! Kind support from two volunteers: Nina Aspey, and Matt McCormack, Durham University Biological Sciences graduate who is joining us in the autumn as our first REFRESH PhD student. A successful day at our peat stream site today with James McDonald, setting up our biofilm cultivation slides so that they are ready for this final experiment in August. The sheep hurdles are to keep the sheep grazing this common out of the experiment!
July 31, 2025 at 6:51 PM
pennyjohnes.bsky.social
Spoke on BBC Radio 4 Farming Today this morning on the implications of the Cunliffe Report for UK farmers and freshwaters, explaining some of the key findings from our @ukri.org funded QUANTUM programme on livestock impacts on www.bbc.co.uk/sounds/play/... 🧪
Farming Today - 22/07/2025: water pollution, farmers' wellbeing - BBC Sounds
Water pollution, farmers' wellbeing.
www.bbc.co.uk
July 23, 2025 at 8:29 AM
pennyjohnes.bsky.social
‪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.
July 11, 2025 at 2:38 PM
pennyjohnes.bsky.social
Great opportunity to win a 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
July 11, 2025 at 2:29 PM
pennyjohnes.bsky.social
Challenging but fun @erc.europa.eu and @ukri.org science now underway! We next add snails to the jars at 96 h, and return to collect them with remaining biofilms and bryophytes at 192 h. Looking forward to @mgenner.bsky.social joining us at 192 h to sample for our omics work. Roles advertised soon!
July 11, 2025 at 9:59 AM
Reposted by Penny Johnes
acastrocastellon.bsky.social
This week I helped setting up the mesocosm experiment for the @ercrefresh.bsky.social programme lead by @pennyjohnes.bsky.social with @jameslmcdonald.bsky.social and Charly Briddon. The landscape was a dream.
July 10, 2025 at 7:22 PM
pennyjohnes.bsky.social
Our team of 3 PDRAs, 3 research techs and 3 PhD students (5 still tba) will work with me, @mgenner.bsky.social & Mark Beaumont of @bristoluni.bsky.social Biological Sciences, and OGU (Ian Bull), @ukceh.bsky.social Dan Read, Ellie Mackay, Daren Gooddy, @bangoruniversity.bsky.social (Davey Jones).
ercrefresh.bsky.social ERC REFRESH programme @ercrefresh.bsky.social · Jul 9
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. The final set up, the evening before the first sampling at time point 0. We then sample at 1.5 h, 6 h, 24 h, 48 h, 96 h (at which point we introduce snails to graze off the biofilms and bryophytes) and 192 h. So many moving parts to go wrong, and each jar 9x 3 replicates) receives a different dual-labelled DOM compound at 1% enrichment of N over background. These are not enrichment nor depletion experiments (those come later in this 5 year ERC Advanced Grant programme, awarded to @penny.johnes.bsky.social ) and funded via @ukri.org under the Horizon Guarantee. The PI @penny.johnes.bsky.social having rather too good a time. Science is always fun, but also often quite challenging when we are conducting experiments under environmental conditions. It's always a relief when the kit is in and working and the design is correct!
July 9, 2025 at 3:37 PM
pennyjohnes.bsky.social
We've now completed our QUANTUM sampling at 33/60 sites, in SW of England, W England and Wales. Next stop N England and Scotland! By focusing on streams draining sheep, beef and dairy farmland, we are building a national picture of their impacts on UK river water quality to better inform policy.🧪
Lowland sheep impacts on streams sampled in SW England in our @ukri.org QUANTUM programme, with help from @a.castrocastellon.bsky.social Beef cattle typically (like sheep) have direct access to watercourses where there is defecation in the channel and poaching of stream bank sediments, contributing to a high risk of contaminant transfer to streams. We are testing samples to determine their ecotoxin, pathogen, nutrient and organic matter composition. In around 50% of dairy farmed catchments, outdoor-grazed livestock are able to directly access streams. This leads to the same impacts as in beef cattle systems. In the other 50%, where animals are housed, water is abstracted to provide the cows with the capacity to produce milk. The average production rate is 22 litres per cow per day, with some high yielding cows producting much more. If a farmer has a herd of 500 cows, this can amount to over 11000 litres of water per farm, exported from the catchment every day in the form of milk or milk products. As a result where there are large commercial herds kept indoors streams often run bone dry or at very low flows in the summer months, reducing their dilution capacity for contaminants, increasing environmental exposure rates for stream biota, and making the stream ecosystem much more susceptible to climate warming effects.
July 2, 2025 at 2:29 PM
pennyjohnes.bsky.social
When livestock have direct access to watercourses, the risk of ecotoxin, pathogen, organic matter and nutrient pollution increases to 100%. Our
@ukri.org QUANTUM programme sampling found some culprits today..... @acastrocastellon.bsky.social @victoriahussey.bsky.social 🧪🐄🐂
An idyllic scene, but hidden within is ecosystem damage as cattle urine and dung are directly voided into the stream or onto the stream margins. Some of the culprits Who did that? A contaminated site. Water flows from her to the river and out to coastal bathing waters. Contaminants include ecotoxins, pathogens, organic matter and nutrients.
June 25, 2025 at 12:10 AM
pennyjohnes.bsky.social
Our @ukri.org QUANTUM national sampling programme is now well underway. Thanks to @acastrocastellon.bsky.social for help with the SW England sites, Sydney Enns and @victoriahussey.bsky.social for prepping the kit, and my husband who helped with the Welsh sites - great cow poo sampling skills! 🧪🐄🐑🐂
Beef cattle, and a very aggressive bull guarding his herd. Dairy cattle in the Cleddau catchment Start of Day 3, in the headquarters of the Tywi catchment before heading over to the Usk. Days 1 and 2 sampled the Cleddau (W and E), Nyfer, Taf, Teifi and Aeron catchments! A sprightly cow during our sampling trip to the W Cleddau. Shout out to the West Wales Nutrient Management Partnership who put us in touch with the farmers, and the farmer who gave us permission to visit their farms.
June 23, 2025 at 9:56 PM
Reposted by Penny Johnes
unep.org
Harmful algal blooms, fueled by nutrient pollution and rising temperatures, threaten marine life and human health by releasing toxins into water and seafood.

We need #ClimateAction and stronger efforts to cut nitrogen and phosphorus pollution.
May 30, 2025 at 8:05 AM
pennyjohnes.bsky.social
As we finish our NERC QUANTUM field experiments and move on to upscaling and modelling work at national scale, we'd like to thank the residents of Rickford and our hugely helpful farmers, Paul and Roger Keel for their support. We'll return in the autumn to tell you what we've found!
Roger Keel, ready to repair the fencing in our enclosure prior to letting the extensive beef cattle back in to graze off the lush grass on our slurry amended plots. @acastrocastellon.bsky.social, @jameslmcdonald.bsky.social, @bristoluni.bsky.social Paul and Roger Keel in conversation with Catchment Sensitive Farming officers at our autumn stakeholder event. Paul in conversation with Ed Fredenham of Bristol Water, during our autumn stakeholder event.
May 29, 2025 at 5:12 PM
pennyjohnes.bsky.social
Last day in the field, returning our NERC QUANTUM field kit to the @bristoluni.bsky.social Fenswood field store where we bumped into our Aviation Engineering colleagues flying drones. They kindly agreed to fly over our field site producing aerial images for our future presentations. Great teamwork!🧪
Aviation Engineering PhD students from University of Bristol, flying a drone over our field site to capture aerial images of the impacts of slurry amendments on vegetation growth. Very grateful to them, as we interrupted them at their summer BBQ and drone festival. Good spot by our new research team member, @jameslmcdonald.bsky.social‬ Drone at the field site, set up to capture aerial and multi-spectral data. Drone flying over our field site at Rickford, N Somerset. @acastrocastellon.bsky.social, @jameslmcdonald.bsky.social‬ Kilian Meier, 2nd year PhD student in the @bristoluni.sky.social Aviation Engineering group, flying a drone over our field site at Rickford, N Somerset.
May 29, 2025 at 4:58 PM
pennyjohnes.bsky.social
Yes indeed! Great work from the team and, if I may say so, brave work from the PI who had to stand in the outer field and hold the theodolite while the cattle licked her coat, while Prof Andy Binley surveyed in the site - 1st principle for PIs: #neveraskyourteamtodosomethingyouwouldn'tdoyourself 🧪🐮
victoriahussey.bsky.social Victoria Hussey @victoriahussey.bsky.social · May 28
A busy day yesterday taking soil cores at our field site for the NERC-funded Quantum freshwater project. The cows kept a close eye on us all day! @pennyjohnes.bsky.social
Three scientists, wearing waterproofs, are stood in a field of long grass holding soil coring tools. There are a herd of cows in the background, stood behind a wire fence.
May 28, 2025 at 6:25 PM
pennyjohnes.bsky.social
Final day of sampling today for the @bristoluni.bsky.social
team at our NERC QUANTUM field site, and the
@exeter.ac.uk QUANTUM team completing their field ecotoxin exposure experiments. This was a fantastic field site for the project. Many thanks to the farmers and villagers for their support.
Professor Charles Tyler, University of Exeter, who leads the QUANTUM programme ecotoxicology work, holding a sample of three-spined stickleback following our field ecotoxin exposure experiments. The University of Exeter Biosciences field team, led by Dr Anke Lange, processing samples from the QUANTUM field ecotoxicology experiment Dr Simona Frustaci, another of our QUANTUM programme PDRAs, with a sample of freshwater shrimp, Gammarus pulex, following the QUANTUM field ecotoxin exposure experiments. Sydney Enns, who with @jameslmcdonald.bsky.social‬, @acastrocastellon.bsky.social‬ and @pennyjohnes@bsky.social, spent the day decommissioning the site, recovering our key for cleaning and prep for other projects, and tidying up the site ready for the cattle to return to the site next week. We also spent the afternoon collecting a final set of soil samples from our control, 40m and 10m slurry amendment plots, to explore downslope nutrient trends (from hillslope to stream) following a year of slurry amendments.
May 28, 2025 at 6:19 PM
pennyjohnes.bsky.social
We had warm sunny weather when we wanted rain for our experiments and now, when we want dry weather to for soil coring and site decommissioning, we had very heavy rain all day. Even so, 62 coring sites surveyed in and cored for our NERC QUANTUM ecotoxin, pathogen, organic and nutrient analyses! 🧪
Prof Andy Binley, Lancaster University with Tony Healey, technical manager at the University of Bristol, surveying in the soil coring sites with the help of Prof Penny Johnes So course extracted ready for ecotoxin pathogen organic geochemistry and nutrient analysis at the universities of Bath, Bangor and Bristol respectively. 62 corling sites across our control strips and our two slurry amended treatment strips. Dr Ana Castro-Castellon with Prof Penny Johnes, midway through coring and both of us thoroughly soaking wet but still cheerful! Dr. Victoria Hussey, Sydney Enns and Dr James McDonald at the start of coring. Six sites into the 62 at 10 am and everyone was already soaked.
May 27, 2025 at 5:36 PM
Reposted by Penny Johnes
acastrocastellon.bsky.social
Research field work has its perks, one gets to be supervised by livestock! Here marking the plots and core sampling points with @pennyjohnes.bsky.social lead of @QUANTUM freshwater and REFRESH projects. James McDonald assisting today.
May 24, 2025 at 7:36 AM
pennyjohnes.bsky.social
More fieldwork fun for QUANTUM and REFRESH teams today. A visit from Welsh Rivers Union, then started site decommissioning following completion of our experiments, and marked up a sample grid for soil coring on our slurry amendment plots next week. Curious cattle made leaving the site tricky! 🧪🐄🐮
Cattle rushing to the fence to find out what we were doing as we marked up the soil coring locations for next week Cattle peering into our field vehicle to check out our supplies and tool kits. Ana trying to chase the cattle away from the gate so we could leave the field experimental area without letting them in to feast on the rich grass on the slurry amended plots
May 23, 2025 at 3:43 PM
Reposted by Penny Johnes
acastrocastellon.bsky.social
There is so much work invested on this experiment that seeing it running is a joy!
May 16, 2025 at 7:35 PM
pennyjohnes.bsky.social
More knowledge exchange and training on the NERC QUANTUM isotope dosing platform, with researchers working with us from the ERC REFRESH and NERC MICRO-CYCLE teams as we collect our 96 hr gas, biofilm and moss samples, and add snails for the final 96 hr period. Final 192 hr samples next week! 🧪
Nellie Farhoudi, specialist research technician on the NERC MICRO-CYCLE programme. Drs Michaela Reay (NERC MICRO-CYCLE) and Ana Castro-Castellon (NERC QUANTUM) PDRAs, downloading our temperature and light sensor data. Pond snails, Lymnaea stagnalis, ready to add to our mesocosms. Today's team: DrJames McDonald (ERC REFRESH), Dr Michaela Reay and Nellie Farhoudi (NERC MICRO-CYCLE) and Dr Ana Castro-Castellon (NERC QUANTUM) after finishing sampling.
May 16, 2025 at 5:17 PM
pennyjohnes.bsky.social
Meet Dr Tolulope Lawrence, one of four PDRAs on our NERC QUANTUM project, who has been presenting at SETAC on her work with Prof Barbara Kasprzyk Hordern, University of Bath, on the analysis of our livestock excreta and freshwater samples for 200 ecotoxin compounds. Great work Tolu! 🧪
SETAC meeting Vienna 2025 Dr Tolulope Lawrence with her SETAC poster Arriving at SETAC
May 15, 2025 at 7:06 AM