Spatial and temporal variability in the phyto- and zooplankton community and important physicochemical factors of the Western Arabian Gulf in 2017 and 2018

Samples for phytoplankton and zooplankton abundance analysis, together with relevant physicochemical data, were collected in Saudi Arabian waters of the Arabian Gulf during summer 2017 and winter to early spring 2018. This study was part of the Sustaining VI project, jointly conducted by King Fahd University of Petroleum and Minerals and Saudi-Aramco. Phytoplankton samples were taken from surface waters, fixed with Lugol's iodine solution and analyzed in the laboratory using the Utermöhl sedimentation technique. Tintinnids were identified as part of the phytoplankton analysis as well. Zooplankton samples were collected through 10 minute horizontal tows of a bongo net with a mesh size of 300 µm. The net was equipped with a mechanical flow meter in order to subsequently calculate the filtered water volume and zooplankton abundances. In the lab, samples were analyzed following the method of Postel et al. (2000). Temperature and salinity were measured in-situ, using a YSI multi-parameter sonde. The photosynthetically active radiation was calculated from satellite measurements (MODIS Aqua). Concentrations of total suspended solids were measured by gravimetric analysis. Macronutrients (nitrite, nitrate, phosphate and silica) were analyzed using segmented flow analysis, while trace metals (copper, iron, molybdenum, nickel, vanadium and zinc) were analyzed by ICP-MS