Biological and Physico-chemical data for LTER ESTUARIES (Mira Estuary LTER_EU_PT_013)

Field data collection with a multiparameters probe in the Mira Estuary.
Environmental parameters were measured with a WTW 330i multiparameter probe

Suspended particulate matter (SPM) was obtained by filtering water through polycarbonate membranes (0.45 µm) and determined gravimetrically (drying at
room temperature)

Water samples for the determination of dissolved inorganic nutrients (nitrate, NO3-, NO2-, ammonia, NH4+

phosphate, PO4- and silicate) were filtered through MSI Acetate Plus filters and analysis carried out using an autoanalyser TRAACS 2000 (Bran+Luebbe)

Niquel, Cr, Cu, Pb, Co and Cd were measured in the collected waters using diffusive gradients of thin films (DGT). Total dissolved mercury was quantified in filtered and acidified water samples by cold-vapour atomic fluorescence spectrometry

Water samples were filtered and extracted with appropriate solvents for the determination of organic compounds by chromatographic techniques.
Zooplankton collections were made with a horizontally towed conical zooplankton net of 335µm mesh size (frame diameter: 0.6 m), paired with a General Oceanics 2003 flowmeter to determine water volume sampled. Tows are performed during 10 minutes and an average speed of 2 knots, near the surface of the water column (approximately 1m below the surface). Samples are immediately preserved in 4% buffered formalin.
Seagrass sampling was performed through the use of a manual corer (13.5 cm inner diameter) for the quantification of biomass (g DW m-2) and shoot density (ind m-2), and by geo-referencing the meadow with the use of a GPS device (covering the margin of the meadow by foot).
Macroinvertebrates were collected using a van Veen grab with 0.05 m2 area.
Fish were collected using a beam trawl with the following characteristics: length - 2 m, height - 50 cm

mesh size (45 mm

5 mm in the cod end)

foot rope with metal chains.