Chlorophyll-a concentration was lower than 0.2 mg m3 in the
upper 50 m during both experiments (Fig. 5). A well developed deep
chlorophyll-a maximum (DCM) was located at the base of the photic
zone (t-student test with Welch’s correction between the averaged
depth of the DCM and the averaged depth of the 1% incident
irradiance measured, n1⁄415 and 81, respectively; t1⁄41.4; p1⁄40.2)
where chlorophyll-a concentrations exceeded 0.3 mg m3
. In general,
the nitracline was slightly deeper than the DCM (Fig. 5). Thus, NO3
plus NO2 concentrations were lower than 1 mmol m3 in the entire
photic zone.