These are replaced by virus-like particles over the following 24 hours, with about
20% of cells infected. Cell abundance then declines, and the free viral abundance
increases.
(^) Most algal viruses appear to be species-specific. Additional studies are under way to
characterize the diversity of algal viruses, host specificity, and the ecological role of
viruses. Eventually we may know how much phytoplankton mortality is due to viral
lysis versus predation.
Phytoplankton Standing Stocks
(^) Although many different types of phytoplankton can be present in seawater samples,
it is often useful to have a measure of the total phytoplankton biomass or standing
stock. Chlorophyll-a is present in almost all phytoplankton, and the amount of it in
seawater is a reasonable, if imperfect, measure of phytoplankton standing stock.
Moreover, chlorophyll concentration is relatively easy to determine. Phytoplankton