FIELD MEASUREMENT OF SPECIFIC GROWTH-RATE, BIOMASS, AND PRIMARY PRODUCTION OF BENTHIC DIATOMS OF SAVIN HILL COVE, BOSTON

C-14-labeling of chlorophyll a and subsequent extraction by high-pressure liquid chromatography (HPLC) was adapted for field measurement of both specific growth rate and biomass of diatom films found on muddy intertidal sediments of Savin Hill Cove, a small embayment of northwest Dorchester Bay, Boston Harbor. Primary production was measured concurrently via C-14 uptake into total cellular C. An incubation apparatus that incorporates stirring to enhance sediment-water gas exchange was used at both low and high tides. Over the year-long study period (August 1987-August 1988) measured specific growth rates were low (0.06-0.27 d-1) while biomass estimates were high (2.21 x 10(-4) to 1.54 x 10(-3) g C cm-2). C:Chl ratios varied from 18.7 to 60.4. The highest biomass values and C:Chl ratios were found during the 1988 spring bloom. The very low specific growth rates measured during the spring bloom (0.06 and 0.09 d-1) coupled with spring increases in the numbers of grazers may explain the steep decline in biomass that followed the spring bloom in 1986-1988.