Primary Production Slides

Primary Productivity

Rate at which energy is stored in organic matter.

Photosynthesis

Process using solar radiation to convert CO₂ and water into organic matter and oxygen.

Chemosynthesis

Production of organic matter using chemical energy instead of sunlight.

Ocean Biomass Dependence

~99.9% depends directly or indirectly on photosynthesis.

Gross Primary Production (GPP)

Total amount of carbon fixed by photosynthesis.

Net Primary Production (NPP)

Carbon available to consumers (NPP = GPP − respiration).

Low Productivity Regions

Central ocean gyres.

High Productivity Regions

Coastal areas and equatorial zones.

Moderate to High Productivity Regions

Polar regions.

Oxygen Method

Measure O₂ production in incubated water samples.

Carbon Tracer Method

Add radioactive carbon to track uptake.

Satellite Monitoring

Uses ocean color (chlorophyll levels) to estimate productivity.

SeaWiFS

Satellite sensor (1997-2010) measuring ocean color.

MODIS

Current system measuring 36 spectral frequencies.

Anthophyta

Seed plants (e.g., seagrasses, mangroves) in shallow coastal waters.

Macroscopic Algae

Large algae (brown, red, green).

Microscopic Algae (Phytoplankton)

Includes diatoms, coccolithophores, dinoflagellates.

Photosynthetic Bacteria

Cyanobacteria; may account for ~50% of ocean photosynthesis.

Euphotic Zone

Upper ~100 m where light supports photosynthesis.

Compensation Depth

Depth where photosynthesis = respiration.

Nutrients

Key: nitrate, phosphorus, iron, silica.

Upwelling

Movement of nutrient-rich deep water to the surface.

Polar Regions (Productivity)

Seasonal productivity (high in summer, low in winter).

Tropical Oceans

Generally low productivity due to poor nutrient mixing.

High Productivity Tropics

Occurs near upwelling zones and coral reefs.

Temperate Oceans

Highly seasonal (spring and fall blooms).

Thermocline

Layer that limits mixing of surface and deep water.

Mixed Layer Depth

Influences light and nutrient availability.