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GOLDYS hydro-biological data : Pelagic seasonal dynamics of the Gulf of Lion (North-western Mediterranean) in 2022-2023
As plankton strongly relies on environmental conditions, its abundance, composition and dynamics often reflect short term and local scale environmental variability. However, in the Gulf of Lion (GoL, northern most part of the western Mediterranean basin), plankton dynamic is still poorly understood particularly regarding its seasonal variations. In addition, major anthropogenic forcing involving heavy fishing pressure in the area have given rise to numerous management plans aimed at protecting the GoL's exploited species, and led to a growing need for knowledge about the overall functioning of this complex ecosystem. A research project aimed at surveying the GoL demersal and pelagic seasonal dynamics (GOLDYS project, 2021-2023) was undertaken to attempt filling this knowledge gap (Jacob, Salvado et al., 2023).
Biological oceanography, Fisheries and aquaculture, Environment
Gulf of Lion, North-western Mediterranean, Hydrology, phytoplankton, zooplankton, ichtyoplankton, seasonal dynamics, exploited fish species
43.6N, 42.4S, 5.2E, 3W
The present dataset, obtained through the GOLDYS and PELMED surveys, covers the results obtained from the pelagic compartment monitoring of the GoL. Between April 2022 and February 2023, a total of 22 stations per season were sampled in the GoL, covering four seasons (spring, summer, autumn, winter) (Vaz et al., 2023). Spring was represented by April and May 2022 samples, Summer by July 2022 samples, Autumn by September to November 2022 samples and winter by December 2022 to February 2023 samples. Additionally, one station, both central and coastal in location (GLD14), was sampled each month during the whole monitoring period. At each station, data on environmental variables, phytoplankton, mesozooplankton, and ichthyoplankton were collected. Hydrological indicators such as surface temperature, surface salinity, mean temperature, mean salinity, equivalent height of freshwater, mixed layer depth, and potential energy deficit were calculated based on temperature, density and salinity profiles obtained from CTD SBE 19plus V2 measurements. Subsequently, the contribution of six phytoplankton taxa (ie diatoms, Dinoflagellata, Prasinophyceae, Haptophyta, Pelagophyceae, Synechococcus, Prochlorococcus) to chlorophyll-a was estimated using pigment-based chemotaxonomy (CHEMTAX, Wright, 2006) of surface water samples. Mesozooplankton (0.2 – 20 mm) was sampled using a 200µm WP2 net, and the density of mesozooplankton organisms was determined through both microscopic analyses and digital image analysis using the ZooScan and Zooprocess software (Gorsky et al., 2010). Finally, ichthyoplankton eggs and larvae were sampled using a double Bongo net (mesh size 350 and 500µm respectively), followed by morphological identification supported by molecular analysis. Molecular analyses were carried out only on coastal samples from the station sampled monthly. The present dataset is composed of two excel files, one containing hydrological, phytoplankton, imagery-derived and microscopy-derived zooplankton data, while the other file contains ichtyoplankton data. Both files are composed of several sheets including a description sheet detailing the content of the following data tables and their fields.