One way to measure zooplankton concentrations is to measure the settled volume of the animals collected in the vertical tow.  While this cannot tell us which species are present, it does provide a measure of zooplankton biomass.  Because of their importance as a food item in the marine food web zooplankton availability is critical to higher trophic levels.  In 1997 we began sampling across Cook Inlet  and noted that the highest concentrations of zooplankton biomass at the edges of the cold water upwelling (see the temperature and salinity profiles from 1998 for comparison) in Lower Cook Inlet.  This is important because we expect that seabirds would focus their foraging activity in areas of high zooplankton concentrations.  This focus of foraging activity is In part because some seabirds are "planktivores" (eat primarily zooplankton), and in part because many of the small fish that consume smaller zooplankton are major prey items for "picivorous" (fish eating) seabirds.

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