Tender: Intertidal Mudflat Monitoring Surveys at Hinkley Point C – Macoma balthica Monitoring (Bridgwater Bay & Wick St. Lawrence)

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Cefas is seeking a supplier for intertidal mudflat monitoring surveys at Hinkley Point C to deliver biological and physical monitoring of the Baltic tellin (Macoma balthica) around Bridgwater Bay and a reference site at Wick St. Lawrence to meet regulatory environmental monitoring requirements. The contract is expected to start mid-February 2026, run initially to 31 December 2028 with two optional 12‑month extensions to a maximum of 31 December 2030. Biological work at high and low shore stations includes six replicate macrofauna samples collected with a 0.01 m² corer to 15 cm depth (sealed and couriered to a Cefas-appointed UK laboratory within 24 hours), hand-collected sieved samples of up to 75 Macoma balthica with an additional 10–15 larger individuals (>1 cm) for condition index, and five replicate sediment cores from the top 2 cm using a 50 ml truncated-tip syringe (four pooled for pigment/nutrient analysis, one for particle size), with samples stored on dry ice and sent to the Lowestoft Cefas Laboratory. Physical monitoring at five low-shore stations requires deployment of Star-Oddi Data Storage Tag DST centi-TD temperature and pressure sensors on metal stakes that remain in situ and provide continuous temperature recording with quarterly data uploads. Biological sampling is required twice yearly during spring-tide windows in February and August, and physical measurements are required four times a year in February, May, August and November (February and August biological and physical work occur during the same survey). Alternative analysis approaches may be proposed within submissions.