Upwelling Case Study – Examining Biological Data
Investigating Biological Conditions
In-water fluorescence data
Deep waters tend to be richer in the nutrients that support plant growth. When transported to the surface by upwelling, these waters warm up and algal growth is stimulated. Rapid growth rates of phytoplankton — i.e., microscopic algae at the base of the food web — cause upwelled waters to be heavily populated by many forms of marine life.
The amount of chlorophyll in the water column is measured using a fluorometer, which hits seawater with blue light, causing the chlorophyll (a common plant pigment) within phytoplankton to glow red. The resulting red fluorescence is used to quantify chlorophyll concentration. The graphs at right show summer fluorescence data through the water column at the M1 and M2 moorings.
Satellites, such as NASA’s SeaWiFS satellite, are also used to gather information about ocean primary production. Subtle changes in ocean color signify various kinds and quantities of phytoplankton. Thus, ocean color data can help determine whether upwelling occurred during the winter months.
The ocean color patterns above indicate that weak upwelling occurred during the winter months. How does this compare with California’s Pacific Sardine landings during winter? Is there a clear seasonal correlation between upwelling and Pacific Sardine landings? If not, what other factors may influence landings?
Before answering, you might wish to investigate data from other seasons:
- Latest SURFACE fluorescence data from the M1 mooring
- Latest SURFACE fluorescence data from the M2 mooring
- Time-series summaries of physical, biological and chemical data from MBARI stations
- SeaWiFs monthly ocean color data from the west coast of N. America (Sep. ’97 – Jul. ’01)