Small-scale patchiness of the chlorophyll-fluorescence in the sea: aspects of instrumentation, data processing, and interpretation

Abstract

Burst series consisting of 5 chlorophyll-fluorescence profiles at 3 min intervals were taken every hour at 3 drift stations over periods of about 15 h each in the transition zone between North and Baltic Seas using a fluorescence sonde, pre-calibrated into in vivo Dunaliella chlorophyll units. Differences in the field between fluorometric readings and water samples analyzed photometrically were not significant. Chlorophyll layers in the Kattegat were about 1 m thick, floating on isopycnal surfaces. Microscale horizontal variability (= standard deviation of 1 burst of profiles) was generally high, reaching a maximum in the pycnocline at high chlorophyll concentrations. Mesoscale variability (= standard deviation of all profiles) observed in chlorophyll, temperature and salinity, may be due to horizontal displacement, advection, and internal waves. The data presented cannot separate the spatial and temporal components of the chlorophyll distribution pattern.