25:["$","title",null,{"children":"Modelling the Artificial Reef Effect | Vekta Group | Observable"}] 49:T51b,With this being the final Insight in this month's series on biodiversity and renewables, this week explores benthic habitats in the context of offshore wind development. A model was developed to assess the potential areas of UK seabed where future offshore wind developments could most effectively boost benthic biodiversity. This model focuses on benthic habitat biodiversity, which refers to ecological zones on the seafloor, including the sediment and sub-surface. These habitats are the foundation of marine ecosystems, supporting a vast range of organisms, from burrowing worms and molluscs to commercially important fish and crustaceans. They play a critical role in nutrient cycling, carbon storage, and food and shelter provision for other organisms.

While offshore wind developments can significantly disturb seabed habitats during construction, their long-term presence may offer net ecological benefits by supporting benthic biodiversity through two key mechanisms. The first is through the creation of artificial reefs. Turbine foundations and associated infrastructure act as hard substrates, which can encourage colonisation of marine organisms. The second is by offering an area of refuge from bottom-towed fishing gear, such as bottom trawlers, once a wind farm is installed.
4a:T774,Each variable was standardised to a 0-1 scale, allowing for uniform comparison and integration into the model. Benthic habitats taken from the International Council for the Exploration of the Seas (ICES) database were classified into seven habitat categories (largely based on European Nature Information System (EUNIS) classification and refined using information from the Join Nature Conservation Committee (JNCC) and the Benthic Indicator Species Index (BISI)). Each category was assigned a score, with higher scores reflecting greater biodiversity potential e.g. reef habitats were given the highest score due to their structural complexity and ecological value.

Bathymetry was simplified into a binary classification based on broad ecological thresholds. Depths between 0 and -50 m were marked as suitable, as they fall within the photic zone where light, temperature, and oxygen conditions support high benthic biodiversity and colonisation of artificial reefs. Deeper areas were marked unsuitable due to reduced light and harsher conditions that limit ecological complexity.

Fishing intensity was assessed based on the type of bottom-contact gear used, with data taken from the Vekta Digital (VD) database. Gear types that contact the benthic surface were included and weighted according to their level of disturbance e.g. dredges were given the highest disturbance rating. Areas with higher fishing intensity were considered less suitable for biodiversity boosting, and scores were reversed before standardisation, so 1 indicates low/no fishing pressure and high ecological potential.

The variables were weighted to reflect their influence on benthic biodiversity. Habitat type and fishing intensity received higher weights (0.4) to reflect their strong, direct impact on ecological conditions. Bathymetry was assigned a lower weight (0.2), due to its more indirect role.4b:T1043,{ const container = yield htl.html`

`; const map = L.map(container); const colorScale = d3.scaleLinear() .domain([0, 1000]) .range([0, 1]) // OS map background L.tileLayer("https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png", { attribution: "© OpenStreetMap contributors", }).addTo(map); const legend = L.control({ position: 'bottomright' }); // Function to style the features based on DN value function styleFeature(feature) { const DN = feature.properties.DN; const color = d3.interpolatePuRd(colorScale(DN)); // Assign color based on DN value return { fillColor: color, color: color, weight: 1, opacity: 1, fillOpacity: 1, }; } // Add suitability layer to the map const suitabilityLayer = L.geoJSON(suitability, { style: styleFeature, onEachFeature: onEachFeature }); // Style the tooltip function onEachFeature(feature, layer) { if (feature.properties && feature.properties.DN !== undefined) { layer.bindTooltip(`Habitat Suitability: ${feature.properties.DN}`, { permanent: false, direction: "top" }); } } // wind farm polygon colours const statusColors = { "In planning": "#1E3A8A", "Consented": "#4F46E5", "Development": "#3B82F6", "Under construction": "#60D5FB", "Operational": "#A9D6F5" }; // Style for wind farm polygons function styleWindFarms(feature) { const props = feature.properties || {}; const status = props.WebsiteSta?.trim() || "Unknown"; const fillColor = statusColors[status] || "#999999"; // default grey for unlisted return { fillColor: fillColor, color: "#000000", weight: 0.5, opacity: 1, fillOpacity: 1, }; } // Add wind farm polygons to the map with a tooltip const windFarmLayer = L.geoJSON(windFarms, { style: styleWindFarms, onEachFeature: function(feature, layer) { const props = feature.properties; const tooltipText = ` ${props.Project}
Status: ${props.WebsiteSta}
Developer: ${props.Developer || "N/A"} `; layer.bindTooltip(tooltipText, { permanent: false, direction: "top", sticky: true }); } }); // Add base + overlay layers suitabilityLayer.addTo(map); // Show suitability by default const overlayMaps = { "Wind Farms": windFarmLayer }; L.control.layers(null, overlayMaps, {collapsed: false}).addTo(map); // map view map.setView([55.3, -2], 5); // legend legend.onAdd = function (map) { const div = L.DomUtil.create('div', 'info legend'); const nStops = 10; // how smooth you want the gradient const stops = [...Array(nStops + 1).keys()].map(i => i / nStops); const gradient = stops .map(t => d3.interpolatePuRd(t)) .join(','); div.innerHTML = ` Habitat Suitability

0 1000

`; div.style.background = "white"; div.style.padding = "10px"; div.style.borderRadius = "5px"; div.style.boxShadow = "0 0 10px rgba(0,0,0,0.2)"; return div; }; legend.addTo(map); // wind legend const windLegend = L.control({ position: 'topright' }); windLegend.onAdd = function (map) { const div = L.DomUtil.create('div', 'info legend'); div.style.background = "white"; div.style.padding = "10px"; div.style.borderRadius = "5px"; div.style.boxShadow = "0 0 10px rgba(0,0,0,0.2)"; div.style.fontSize = "12px"; div.innerHTML += `Wind Farm Status
`; for (const [status, color] of Object.entries(statusColors)) { div.innerHTML += `

${status}

`; } return div; }; windLegend.addTo(map); } 4c:T4e1,The interactive map of the combined model output (0-1 scale multiplied to represent integers) shows strong spatial patterns in suitability across the UK's EEZ. Coastal areas, particularly those with shallow sandy habitats tend to show the highest suitability for supporting benthic biodiversity. There is a concentration of high suitability areas along the eastern and southern coasts, which is likely due to the presence of existing reef habitats. This shows that coastal margins are key zones for future biodiversity-sensitive offshore wind developments. In contrast, deeper areas or regions with intense bottom trawling pressure show reduced suitability, such as off the North East coast of Scotland.

Use the toggle in the right hand box to overlay current and proposed wind farm developments and explore how well these align with areas deemed most beneficial for biodiversity. Some areas of the model display very low or zero suitability values, primarily due to incomplete data in one or more of the input layers. These gaps have been retained rather than filled or interpolated to avoid biasing the results, and highlight areas where more detailed ecological data would be beneficial for refining future suitability assessments.
4d:T415,To explore how current offshore wind development aligns with the model’s biodiversity potential, suitability scores were extracted for each wind farm polygon and plotted by development stage. The scatterplot reveals a noticeable trend of operational wind farms occupying areas with higher biodiversity suitability scores, aligning with locations where the artificial reef effect and reduced fishing pressure may already be delivering ecological benefits.

Wind farms in earlier stages show a broader spread and are often located in areas with lower suitability scores. This could indicate a missed opportunity to fully leverage the ecological benefits that wind farms can provide. The variation across development stages underscores the value of incorporating habitat-specific biodiversity potential into early siting decisions. Projects in the consenting or planning stages may benefit from reevaluation to better align with zones where offshore wind could offer both renewable energy generation and benthic biodiversity enhancement. 4e:T42c,This model offers a conceptual tool to guide the placement of future offshore wind farms, helping identify locations where biodiversity benefits could be maximised. It can also support mitigation strategies or biodiversity offsetting, especially where developments are planned in areas of lower ecological value that could be enhanced.

Whilst offshore wind developments initially disturb benthic habitats during construction, the long term ecological benefits might outweigh this. This also raises the question of ecological implications of decommissioning. Removal of wind farm infrastructure could disrupt the newly established reef-like habitats for minimal financial return - typically recovering only a small fraction (~4%) of initial capital expenditure after material resale, compared to estimated decommissioning costs of around 10%.

Looking ahead, the model could be further refined by incorporating species observation data and and real-world monitoring data from existing wind farms to better validate predictions of biodiversity outcomes.4f:[{"id":"713a78ac2f6f5a99d05d2d9db7ddfbe0567b979e75bcfffb1e9df109aaf196f1e5f80c9de61e8e827ff6c5a0a4711ebb95f839c0ec3212ec18e64fcdb3a21d47","href":"https://static.observableusercontent.com/files/713a78ac2f6f5a99d05d2d9db7ddfbe0567b979e75bcfffb1e9df109aaf196f1e5f80c9de61e8e827ff6c5a0a4711ebb95f839c0ec3212ec18e64fcdb3a21d47","name":"Modelling the Artificial Reef Effect@1.png","type":"image/png","lastModified":1745413300486.43,"size":533476},{"id":"266d0416fecba85594bedf87f1e174bc1801bb0d78305a13e13d7a327ee963129d267b38b5a826a353011f39a36f0aaf965497fa3ae4bef3e5ea3b9589e9bb60","href":"https://static.observableusercontent.com/files/266d0416fecba85594bedf87f1e174bc1801bb0d78305a13e13d7a327ee963129d267b38b5a826a353011f39a36f0aaf965497fa3ae4bef3e5ea3b9589e9bb60","name":"windfarms_zonalstats.geojson","type":"application/geo+json","lastModified":1745429732364.63,"size":408916},{"id":"4385377552a089345554b4d4961b9368aa3106af1478976d500966902f7395c7bffb9f38fd99eb76d1ba2ca3c8d531347154de7217fdfee39d2dc3da9b077e95","href":"https://static.observableusercontent.com/files/4385377552a089345554b4d4961b9368aa3106af1478976d500966902f7395c7bffb9f38fd99eb76d1ba2ca3c8d531347154de7217fdfee39d2dc3da9b077e95","name":"windfarms_zonalstats_csv.csv","type":"text/csv","lastModified":1745437389350.193,"size":25279},{"id":"adac81d85339432c75128410c273a3a69ceff1b3465ec10b4338dcfda9bd030558288355b499f7f4c42c26519e54f61f90329348d2a5dc4f1047cac980c3c833","href":"https://static.observableusercontent.com/files/adac81d85339432c75128410c273a3a69ceff1b3465ec10b4338dcfda9bd030558288355b499f7f4c42c26519e54f61f90329348d2a5dc4f1047cac980c3c833","name":"suitability.geojson","type":"application/geo+json","lastModified":1745336691624.022,"size":28822615}] 29:{"id":"b0de710cade025db","slug":null,"title":"Modelling the Artificial Reef Effect","thumbnail":"6cc3fb51a7e7cf8d15ec717fa6612033257921e52092d448d3b39bab2cd0a7d6","access_level":"public","create_time":"$D2025-04-22T12:01:22.745Z","update_time":"$D2025-04-24T11:55:44.597Z","view_time":null,"first_public_time":"$D2025-04-23T09:33:32.696Z","has_unpublished_edits":null,"fork":true,"stars":0,"starred":false,"owner":{"type":"team","id":"3594fe6877d14711","login":"vekta-group","name":"Vekta Group","avatar_url":"https://avatars-next.observableusercontent.com/13f6934c06a2c847905f92615bfe639e05a96b39badbe0036f3139b0c24ef101","tier":"starter_2024","bio":"","followed_by_you":false,"follows_you":false},"version":917,"publish_version":null,"role":null,"authored":false,"authors":[{"type":"individual","id":"353739170940576d","login":"vekta-group","name":"Vekta Group","avatar_url":"https://avatars-next.observableusercontent.com/13f6934c06a2c847905f92615bfe639e05a96b39badbe0036f3139b0c24ef101","tier":null,"bio":"","followed_by_you":false,"follows_you":false}],"members":[{"type":"individual","id":"353739170940576d","login":"vekta-group","name":"Vekta Group","avatar_url":"https://avatars-next.observableusercontent.com/13f6934c06a2c847905f92615bfe639e05a96b39badbe0036f3139b0c24ef101","tier":null,"role":"editor"},{"type":"team","id":"3594fe6877d14711","login":"vekta-group","name":"Vekta Group","avatar_url":"https://avatars-next.observableusercontent.com/13f6934c06a2c847905f92615bfe639e05a96b39badbe0036f3139b0c24ef101","tier":"starter_2024","role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"lapsed":null,"subscribed":null,"forks":1,"collection":null,"type":"notebook","body":{"titling":"auto","title":"Modelling the Artificial Reef Effect","cells":[{"id":0,"value":"# Modelling the Artificial Reef Effect","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":253,"value":"$49","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":7,"value":"## Building the Model","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":434,"value":"The spatial extent of this model covers the UK's Exclusive Economic Zone (EEZ), focusing on British offshore wind developments. Three environmental variables (habitat type, bathymetry, and fishing intensity) were used to assess the suitability of benthic habitats for supporting biodiversity in the context of offshore wind farm developments.","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":291,"value":"vars_img = FileAttachment(\"Modelling the Artificial Reef Effect@1.png\").image()","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":279,"value":"$4a","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":199,"value":"$4b","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":257,"value":"$4c","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":19,"value":"## Benthic Biodiversity and Wind Farms","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":816,"value":"$4d","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":596,"value":"Plot.plot({\n x: { \n label: \"Project Status\",\n domain: [\"In planning\", \"Consented\", \"Development\", \"Under construction\", \"Operational\"] // Ensure all stages are included\n },\n y: { \n label: \"Mean\"\n },\n marks: [\n Plot.dot(data, {\n x: \"stage\",\n y: \"mean\",\n fill: d => {\n if (d.stage === \"In planning\") return \"#1E3A8A\";\n if (d.stage === \"Consented\") return \"#4F46E5\";\n if (d.stage === \"Development\") return \"#3B82F6\";\n if (d.stage === \"Under construction\") return \"#60D5FB\";\n if (d.stage === \"Operational\") return \"#A9D6F5\";\n return \"gray\"\n }\n }),\n Plot.tip(data, Plot.pointerY({\n x: d => d.stage,\n y: d => d.mean,\n title: d => `Project: ${d.project}\\nMean: ${d3.format(\".2f\")(d.mean)}`\n })),\n ],\n color: {\n legend: true\n },\n width: 800,\n height: 500\n})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":259,"value":"$4e","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":9,"value":"
\n## Appendix","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":845,"value":"BISI report: https://ecoauthor.net/wp-content/uploads/2017/10/Final-report-Benthos-Indicator-North-Sea-v260917-EN.pdf\n
\nJNCC benthic habitats: https://data.jncc.gov.uk/data/fb82e7cc-8ee2-494b-8af7-2360d809dee9/JNCC-Report-499-AMENDED-WEB.pdf","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":112,"value":"### Data","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":893,"value":"### Building the Model","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":133,"value":"suitability = FileAttachment(\"suitability.geojson\").json()","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":347,"value":"windFarms = FileAttachment(\"windfarms_zonalstats.geojson\").json()","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":898,"value":"### Benthic Biodiversity and Wind Farms","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":728,"value":"windfarms_zonalstats_csv = await FileAttachment(\"windfarms_zonalstats_csv.csv\").csv({typed: \"auto\"})","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"windfarms_zonalstats_csv","database":"$undefined"},{"id":478,"value":"windFarmData = windfarms_zonalstats_csv","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":732,"value":"data = windFarmData.map(d => ({\n project: d.Project,\n stage: d.WebsiteSta,\n mean: d.modelmean,\n range: d.modelrange\n}))","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":123,"value":"html``","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W4f","stdlib":"1"}} 24:null