Open Oceans: Pelagic Ecosystems III

Comparing the makeup of water and plankton

• Mean Elemental Ratios of N, and P• Organisms: 16.0N / 1P• Sea Water: 14.7N / 1P

• On average, seawater lacks sufficient organic N to take advantage of the available phosphorus

Limited water mixing further limits nutrient availability

Testing models: measuring plankton in open oceans

• Techniques for studying plankton consumers

• Plankton levels may be dropping (NASA study)

Changes in Productivity

                      

From productivity to food webs: A size-based pelagic food web

Grazing pressure

Limits & Flows of NPP

Marine “Snow”

krill

A spatially realistic pelagic food web

What are links among trophic levels in pelagic systems?

Large phytoplankton vary with depth

Nutrient distribution with depth

Distribution of food web biomass

The global nitrogen cycle

Influences on biologically useful Nitrogen

Diatom mats can migrate vertically

Consequences of active transport of NO3

Links to oceanic nekton