320
predictions. How will changes in the surface ocean environment (temperature, seasonal
stratification, ice cover etc.) influence the growth and distributions of the major phytoplankton
groups such as diatoms and coccolithophores?
New techniques of individual particle analysis will contribute significantly to studies of the
second problem particularly for types of phytoplankton, including coccolithophores, with
complex optical properties and with life cycles that are difficult to investigate by standard
microscopy. For E. huxZeyi the satellite images (Figs. 2, 6) provide information on the spatial
and temporal development of a single population (or set of populations), but the significance
of the distributions and roles of the different life stages or of distinct genetic strains (Brand,
1982) for population dynamics of the species (including annual variations in abundance) is not
known. Immunochemical techniques to identify non-calcifying cells of E. huxleyi have now
been developed (Shapiro et al., 1989) and, in conjunction with measurements of side
scattering to detect intracellular coccolith formation, represent a powerful new approach to
studying the dynamics of natural populations.
The process of calcification in coccolithophores is still poorly understood (Borowitzka, 1987;
Sikes and Fabry, 1990) in terms both of biochemistry and of the effects of environmental
factors (light, nutrients) on the partitioning of carbon and energy between organic matter
synthesis and calcite formation. New single-cell methods of studying the uptake of carbon and
calcium as well as intracellular variations in pH (e.g. Dixon et aI., 1989) will enable
significant progress on these topics. Knowledge of the properties of coccoliths is important
for investigations of sinking rates, ingestion and packaging by zooplankton (Cadee, 1986), the
content of and binding capacity for organic carbon, and the isotopic ratios for carbon and
oxygen in calcite. Methods to sort and count coccolithophores and to label specific associated
organic compounds such as matrix polysaccharides (Westbroek et aI., 1989) are just beginning
to be applied in plankton and sediment studies. A better understanding of the relationship
between the stability of adsorbed organic carbon and the dissolution at depth of calcite under
oxic and anoxic conditions is of particular relevance to the oceanic carbon cycle.
Finally, estimates of the conversion efficiency of DMSP in cells to DMS in the atmosphere
will depend on new information about grazing rates of coccolithophores (see Dacey and
Wakeham, 1986) and about the degradation of both DMSP and DMS by marine microbes
(Kiene and Bates, 1990). Flow cytometric techniques have yet to be used in this context but
represent a potentially powerful tool for studies of the role of the ocean biota in the sulphur
cycle.
predictions. How will changes in the surface ocean environment (temperature, seasonal
stratification, ice cover etc.) influence the growth and distributions of the major phytoplankton
groups such as diatoms and coccolithophores?
New techniques of individual particle analysis will contribute significantly to studies of the
second problem particularly for types of phytoplankton, including coccolithophores, with
complex optical properties and with life cycles that are difficult to investigate by standard
microscopy. For E. huxZeyi the satellite images (Figs. 2, 6) provide information on the spatial
and temporal development of a single population (or set of populations), but the significance
of the distributions and roles of the different life stages or of distinct genetic strains (Brand,
1982) for population dynamics of the species (including annual variations in abundance) is not
known. Immunochemical techniques to identify non-calcifying cells of E. huxleyi have now
been developed (Shapiro et al., 1989) and, in conjunction with measurements of side
scattering to detect intracellular coccolith formation, represent a powerful new approach to
studying the dynamics of natural populations.
The process of calcification in coccolithophores is still poorly understood (Borowitzka, 1987;
Sikes and Fabry, 1990) in terms both of biochemistry and of the effects of environmental
factors (light, nutrients) on the partitioning of carbon and energy between organic matter
synthesis and calcite formation. New single-cell methods of studying the uptake of carbon and
calcium as well as intracellular variations in pH (e.g. Dixon et aI., 1989) will enable
significant progress on these topics. Knowledge of the properties of coccoliths is important
for investigations of sinking rates, ingestion and packaging by zooplankton (Cadee, 1986), the
content of and binding capacity for organic carbon, and the isotopic ratios for carbon and
oxygen in calcite. Methods to sort and count coccolithophores and to label specific associated
organic compounds such as matrix polysaccharides (Westbroek et aI., 1989) are just beginning
to be applied in plankton and sediment studies. A better understanding of the relationship
between the stability of adsorbed organic carbon and the dissolution at depth of calcite under
oxic and anoxic conditions is of particular relevance to the oceanic carbon cycle.
Finally, estimates of the conversion efficiency of DMSP in cells to DMS in the atmosphere
will depend on new information about grazing rates of coccolithophores (see Dacey and
Wakeham, 1986) and about the degradation of both DMSP and DMS by marine microbes
(Kiene and Bates, 1990). Flow cytometric techniques have yet to be used in this context but
represent a potentially powerful tool for studies of the role of the ocean biota in the sulphur
cycle.