An Alternative Framework to Assess Marine Ecosystem Functioning in Shelf Seas (AlterEco) Slocum Glider data, February to October 2018 in the North Sea. Involving units 436 (Stella), 345 (Cabot), 305 (Dolomite) during missions AE2, AE3 and AE4 respectively.

(1) National Oceanography Centre, Liverpool; (2) Helmholtz Centre for Ocean Research, Kiel (West Shore Campus); (3) National Oceanography Centre, Southampton

As part of the Alternative Framework to Assess Marine Ecosystem Functioning in Shelf Seas (AlterECO) project (NERC grant reference NE/P013902/1), Slocum gliders (units 436, 345 and 305) were deployed in a physically dynamic region of the North Sea, known to undergo seasonal oxygen depletion, over a period of nine months (February to October 2018). These deployments are part of an 18 month observational programme using marine autonomous vehicles. During each deployment the gliders tracked repeat North-South transects close to Dogger Bank and recorded over 6000 hours of data. Each glider carried a standard CTD package measuring temperature and water conductivity (salinity), an oxygen optode sensor and additional optical sensors for chlorophyll fluorescence, turbidity, CDOM fluorescence and PAR (excluding Unit 305), providing high resolution measurements of key hydrographical and biogeochemical parameters. During this 3 year programme and by developing and implementing a novel monitoring framework, AlterEco aims to deliver an improved spatio-temporal understanding of shelf sea function and provide measurements of critical indicators of marine ecosystem health over seasonal timescales.