Problems in Studying Nitrogen Cycling through Filter-Feeding Bivalve and Phytoplankton : A Review

Feeding strategy, nitrogen cycling, and profitability of dairy farms.

On a typical dairy farm today, large amounts of N are imported as feed supplements and fertilizer. If this N is not recycled through crop growth, it can lead to large losses to the atmosphere and ground water. More efficient use of protein feed supplements can potentially reduce the import of N in feeds, excretion of N in manure, and losses to the environment. A simulation study with a dairy fa...

Bivalve Grazing Can Shape Phytoplankton Communities

The ability of bivalve filter feeders to limit phytoplankton biomass in shallow waters is well-documented, but the role of bivalves in shaping phytoplankton communities is not. The coupled effect of bivalve grazing at the sediment-water interface and sinking of phytoplankton cells to that bottom filtration zone could influence the relative biomass of sinking (diatoms) and non-sinking phytoplank...

Nitrogen Metabolism in Phytoplankton

Cycling of colloidal organic carbon and nitrogen during an estuarine phytoplankton bloom

To establish the influence of phytoplankton blooms on the cycling of dissolved and particulate species of organic carbon and nitrogen, we conducted a field study during a series of blooms in a coastal embayment on Shelter Island, NY. Using cross-flow filtration, we collected highand low-molecular-weight (HMW and LMW) dissolved organic matter (DOM), along with particulate organic matter (POM). T...

Phytoplankton Nitrogen in the Oceans

The ratio of cellular nitrogen and chlorophyll has been studied in cultures of marine phytoplankton during and after recovery from nitrogen deficiency. The time factors were observed to vary together; however, the ratio was only constant when the cells were sufficient in nitrogen. Since nitrogen deficiency produced chlorotic cells in all species studied, the degree of deficiency could be ascert...