Dataset on coastal water quality in an Atlantic sea bass farm site in Sines, Portugal

Description

The dataset is composed of water quality parameters distributed in time (date and time) and space (station ID, latitude, longitude, and depth). Data was collected at the surface and along the water column in 4 sampling stations placed along sea bass aquaculture cages: : station 1 (37.93272, -8.855261), station 2 (37.92932, -8.851303), station 3 (37.92775, -8.847949), station 4 (37.92482, -8.843557). Sampling took place in six field campaigns on 29/06/2018, 25/10/2018, 12/03/2019, 30/04/2019, 23/05/2019 and 29/07/2019. The dataset comprises two data files: (i) discrete data from laboratory analysis (Suspended Particulate Matter (SPM), Turbidity (Tur), dissolved nutrients (NH4+, NO3- + NO2, PO43-, and SiO2) , phytoplankton pigments (Chlorophyll-a (Chl-a), Fucoxanthin (Fuco), Peridinin (Peri), Chlorophyll-b (Chl-b), Alloxanthin (Allo), Zeaxanthin (Zea), 19-Hex, 19-Butanoyloxyfucoxanthine (19-But)) and microscopy data (relative abundance of Bacillariophyceae, Dinophyceae, Haptophyceae , Prasinophyceae, Euglenophyceae, Cryptophyceae, and Cyanophyceae; and relative abundance of potentially harmful species) and discrete data acquired with the multiparametric sonde (Dissolved Oxygen (DO), pH); (ii) continuous data casted along water column profiles with the CTD probe (Temperature (T) and Salinity (S)).

Steps to reproduce

T and S vertical profiles were measured at each sampling station using a CTD probe (model NXIC, from FSI). DO and pH were measured using a multiparametric probe (model EXO2, from YSI) with a DO meter (YSI optical dissolved oxygen sensor) and a pH meter (YSI pH/redox sensor). At each sampling station, water samples were collected using a 5 L Van Dorn. To quantify SPM, dissolved nutrients, and phytoplankton pigments (including Chl-a), the water samples were filtered within 3 h after collection. Turb was measured on the sampling day and did not require any filtration. For qualitative microscopic analysis of phytoplankton, water samples of 125 mL were collected with a 20 μm phytoplankton net vertically towed (from 10 m depth until surface). Samples were immediately preserved with Lugol’s Iodine (12 mL) in dark flasks. Filtrations: (i) for SPM, pre-ashed (450 °C for 4 h) and pre-weighted type GF/F Whatman filters of 0.7 μm nominal pore size and 47 mm diameter, (ii) for dissolved nutrients, polycarbonate GF/C Whatman filters with 1.2 μm porosity and 47 mm diameter; (iii) for phytoplankton pigments, GF/F filters with nominal pore size 0.7 μm and 25 mm diameter. The filtration for dissolved nutrients was performed using a manual filtration set whilst for SPM and phytoplankton pigments a filtration system coupled to a vacuum pump (pressure 200 mbar) was used. PM filters were stored at -20 °C in Petri dishes and analyzed within one week. For dissolved nutrients, water aliquots were stored in test tubes at -20 °C until analysis within 30 days. The phytoplankton pigment filters were immediately frozen at – 80 °C in cryotubes and analyzed within 30 days. SPM was quantified following the standard gravimetric method described in Van der Linde (1998). The dry mass was measured with a precision scale (Mettler AE160). Turbidity was determined with a portable infrared turbidimeter (Lovibond TB 210 IR). Dissolved nutrients were quantified using colorimetric analysis with a Tecator FIAstar 5000 Analyser (except ammonium). Nitrite, nitrate, phosphates, and silicates were determined according to Bendschneider and Robison (1952), Grasshoff (1977), Murphy and Riley (1962) and Fanning and Pilson (1973), respectively. Ammonium concentrations were determined using manual colorimetric according to Koroleff (1969), using a Shimadzu spectrophotometer (UV-2600). Phytoplankton pigment analysis was performed using reversed phase HPLC following Zapata et al. (2000) adapted by Mendes et al. (2007) using a Shimadzu (Prominence I LC-2030C 3D) with a Fluorescence Detector (Shimadzu RF-20A Prominence), with LabSolution Lite version 5.82 software. The samples preserved with Lugol’s Iodine were analyzed in the laboratory using an inverted light microscope Axiovert 200 (Zeiss), with an Axiovision camera attached.

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