EFFECT OF SAMPLING FREQUENCY ON MEASUREMENTS OF SEASONAL PRIMARY PRODUCTION AND OXYGEN STATUS IN NEAR-SHORE COASTAL ECOSYSTEMS

New automated in situ techniques were used for high-resolution time series measurement of primary production and water column oxygen concentration in near-shore coastal marine embayments. Results revealed 2-fold day-to-day fluctuations in measured phytoplankton production, and periodic changes in water column oxygen concentration as great as 100 muM occurring in a matter of a few hours. Effects of sampling frequency upon the determination of seasonal primary production and water column oxygen status were assessed by subsampling the high-resolution measurements at various intervals and reanalyzing of the desired parameters using the lower-resolution data. Results indicate that ecosystem studies using classic measurement intervals (e.g. 30 d) may be undersampled 5- to 30-fold with respect to both primary production and oxygen concentration, resulting in serious inaccuracies in data crucial to ecological and water quality studies.