The Western Channel Observatory: a century of oceanographic, chemical and biological data compiled from pelagic and benthic habitats in the Western English Channel 1903 - 2022

The Western Channel Observatory (WCO) comprises a series of pelagic, benthic and atmospheric sampling sites within 40 km of Plymouth UK, which have been sampled by the Plymouth Institutes on a regular basis since 1903. This longevity of recording and the high frequency of observations provide a unique combination of attributes, for example temperature data began to be collected in 1903 and the reference station L4 has been sampled on a weekly basis since 1988 where nearly 400 planktonic taxa have been enumerated. Some of these data are publicly available, but use of the WCO data is hampered by different levels of data availability and formatting. This dataset integrates average monthly values of some of the key pelagic and benthic measurements for the inshore site L4 (~54 m water depth), the offshore site E1 (~75 m depth) and L5. In summary, the data include: temperature (from 1903); macronutrients (from 1934); dissolved inorganic carbon and total alkalinity (from 2008); methane and nitrous oxide (from 2011); chlorophyll a (from 1992); pigments determined by HPLC (from 1999); pico and nanoplankton groups from flow cytometry (8 functional groups from 2007); phytoplankton (6 functional groups from 1992); FlowCam (6 groups from 2012), Noctiluca (from 1997); zooplankton (8 groups from 1988); Calanus helgolandicus egg production rates (from 1992); fish larvae from Young fish trawl survey (4 groups from 1924); benthic macrofauna (4 groups from 2008); demersal fish (19 families from 2008); blue shark, Prionace glauca (from 1958); 16s alpha diversity for sediment and water column (from 2012). These data have varying coverage in time and depth resolution. The metadata provides pointers to the source data and other related WCO data sets and outputs not compiled here. We hope that making the data fully accessible, and including units of both abundance and biomass, will stimulate a variety of uptakes. These may include uses as an educational resource for projects, for models and budgets or for analysis of seasonality and long-term change in a coupled benthic-pelagic system and for supporting UK and NE Atlantic policy and management.