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Clément Violet

@clementviolet.bsky.social
58 followers 154 following 11 posts

PhD Marine Ecology | Postdoc on Marine Non Indigenous Species | IFREMER 🐬🇫🇷

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Clément Violet @clementviolet.bsky.social · 12/05/2026
Thank you @aec13.bsky.social for this highligth! Check out the paper, the data and the app! 🤩
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Clément Violet @clementviolet.bsky.social · 19/03/2026
Sure thing! All the data are on Zenodo: zenodo.org/records/1097... If you need any help navigating the different files, feel free to DM me
zenodo.org
Leveraging Citizen Science to Classify and track Benthic Habitat States: an Unsupervised UMAP-HDBSCAN Pipeline applied to the Global Reef Life Survey Dataset
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Clément Violet @clementviolet.bsky.social · 13/02/2025
A big thank also to you, all the Reef Life Survey volunteers, without whom this work would not have been possible!
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Clément Violet @clementviolet.bsky.social · 13/02/2025
I would like to warmly thank all the co-authors for their invaluable help with this @aurelien-boye.bsky.social, Rick Stuart-Smith, Graham J. Edgar, Elizabeth Oh, Stanislas Dubois and Martin Marzloff.
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Clément Violet @clementviolet.bsky.social · 13/02/2025
🌍 Understanding habitat states & transitions is key for conservation! 🏝️ Helps track ecosystem shifts from climate change 🛑 Detects early warning signs of degradation (e.g., kelp loss → urchin barrens).
Change in the cluster composition of the Beware Reef. This site shiffted into an urchin barren in 2013 as show by the disaperence of large canopy algae (dark blue line).
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Clément Violet @clementviolet.bsky.social · 13/02/2025
🌍 With our data-driven standardized way to classify & monitor marine habitats, what did we find? 🏝️ 17 distinct habitat states, including kelp forests, coral reefs & transitional zones 📉 Our pipeline captures fine-scale ecological changes over time
Description of the identified clusters along with photoquadrats examples. Arrows indicate transitions between clusters.
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Clément Violet @clementviolet.bsky.social · 13/02/2025
This study wouldn’t be possible without citizen scientists! 🌍🌊 👩‍🔬 Reef Life Survey divers collected 6554 transects worldwide 📸 Standardized photoquadrat sampling ensured consistency 📊 It enabled us to track habitat transitions over time
Map of the number of RLS transect sampled per ecoregion.
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Clément Violet @clementviolet.bsky.social · 13/02/2025
Machine learning models like UMAP & HDBSCAN are powerful, but they’re often hard to interpret. So, we used SHAP to: 📌 Identify which features drive cluster formation 📌 Uncover non-linear interactions in benthic ecosystems 📌 Improve ecological interpretability of results
Using SHAP to Interpreting this cluster as a Foliose brown algae cluster.
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Clément Violet @clementviolet.bsky.social · 13/02/2025
We used better methods: UMAP (for dimension reduction) & HDBSCAN (for clustering). ✅ Captures complex ecological structures ✅ Finds clusters of varying shapes & sizes ✅ Filters noise instead of forcing data into clusters
UMAP ordination of the benthic cover data. Each point is coloured accordingly to its cluster. Black points represent unclustered data.
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Clément Violet @clementviolet.bsky.social · 13/02/2025
Clustering is widely used in ecology to define community types, habitat states & biodiversity patterns. But common methods used in ecology have major drawbacks. (See this excellent video of @JohnDataHealy youtu.be/dGsxd67IFiU?...)
youtu.be
HDBSCAN, Fast Density Based Clustering, the How and the Why - John Healy
YouTube video by PyData
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Clément Violet @clementviolet.bsky.social · 13/02/2025
🚀 New paper alert! We used a UMAP-HDBSCAN pipeline to classify & track benthic habitat states at a global scale using citizen science data from Reef Life Survey ! 🌍🏝️ 🔗 Read it here: doi.org/10.1016/j.ec... #MarineScience #Ecology #CitizenScience #MachineLearning
doi.org
Redirecting
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Reposted by Clément Violet
Amelia Curd @aec13.bsky.social · 11/02/2025
Great talk @clementviolet.bsky.social given during the #BIOcean5D general assembly @ICM-CSIC! So much work went into looking up all those marine NIS native origins and building the ✨ Shiny app.Can’t wait to see the future #Rpackage #marineecology #ultraviolet 🧪🦀🐚🌱🪸 @ifremer.bsky.social
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