https://doi.pangaea.de/10.1594/PANGAEA.996148Thomas, Oliver RobertOliver RobertThomas0009-0000-1636-9492Unsworth, Richard K FRichard K FUnsworthSwansea UniversityPANGAEA2026Field experimentIn-situMonitoringrestorationSeagrass Ocean Rescue North Wales (SORNW)2023-02-20T00:00:00/2025-10-08T00:00:00Bundled Publication of Datasets10.1088/1748-9326/ae6d1710.48670/MOI-0005410.48670/MOI-000555 datasetsapplication/zipCreative Commons Attribution 4.0 InternationalThis data package contains restoration, monitoring and in-situ environmental data collected between February 2023 and October 2025 in support of a study on the resilience of restored seagrass (Zostera marina) meadows to marine heatwave exposure in North Wales, United Kingdom (Thomas et al., 2026). Seagrass was planted at four intertidal sites along the Llŷn Peninsula and Ynys Môn using directly injected seeds, hessian bags and seed balls; planting locations were surveyed with a differential Global Positioning System (dGPS) receiver, producing spatial point and polygon records of the planted areas. Restoration success was subsequently assessed through repeated intertidal quadrat surveys recording shoot and reproductive shoot density, rhizome presence, canopy height, percentage cover of seagrass, epiphytes and algae, and sediment redox potential, pH and temperature, measured using a portable multiparameter meter. In-situ seawater/intertidal temperature and light intensity were additionally recorded at 30-minute intervals over one month in May 2024 using a fixed temperature/light data logger. These restoration and monitoring records were combined with satellite-derived sea surface temperature and marine heatwave indicator data from the E.U. Copernicus Marine Service (doi:10.48670/moi-00054, doi:10.48670/moi-00055) to evaluate how marine heatwave exposure affected the establishment and persistence of a restored seagrass meadow. The package comprises four data types - in-situ light and temperature logger data, spatial point and polygon data of planting locations, seagrass planting records, and seagrass monitoring records - each published here as an individual dataset.-4.587140999999974-4.31945083300001952.8661299553.320517Natural Environment Research Councilhttps://doi.org/10.13039/501100000270NE/V016385/1The National Lottery Heritage Fundhttps://doi.org/10.13039/501100016135NL-21-00035