Both sampling cruises started from Station 1 at high tide and
followed the ebb tide flow to avoid biases due to the tidal cycle.
Temperature, salinity and turbidity were measured along the
entire water column using a YSI 6600 multiparameter sonde.
Quantum Scalar Irradiance (QSI) was measured with a LI-COR
250A radiometer equipped with a LI-193 Underwater Spherical
Quantum Photosynthetic Active Radiation (PAR) sensor. The depth
of the euphotic layer (1% of incident light) and the coefficient of
light extinction were calculated from the model of Beer–Lambert,
Ln Iz = Ln I0 − kz, where Iz is the irradiance at certain depth, I0
is the irradiance in the surface water, and k is the light extinction
coefficient.