Upwelling Flashcards
Upwelling
Water that rises to the surface due to upwelling is typically colder and is rich in nutrients. These nutrients “fertilize” surface waters, meaning that these surface waters often have high biological productivity. Therefore, good fishing grounds typically are found where upwelling is common.
Types of upwelling
o Wind induced upwelling (Gulf of Panama)
o Island or seamount upwelling (Galapagos)
o Wind/current upwelling (eastern boundary currents): California, Peru, Canary & Benguela currents
o Monsoonal: Somali current
o Equatorial divergence
o Divergence of open ocean or currents
What percentage of fisheries catches come from only the top five upwelling zones?
25%
Zones where upwelling occurs…
an increase in primary production
What is the driver of phytoplankton blooms?
Primary productivity
What does primary production require?
Sunlight and nutrients
What is limited by primary production?
Fish production
Definition: Autotroph
produce their own food for energy – use photosynthesis (grass, plants, some bacteria, algae)
Definition: Heterotroph
– consumers – eat other organisms to get protein and energy (grasshopper, toad)
What are the base of the food web?
Photosynthetic organisms (autotrophs)
What are some characteristics of the food web?
-Organisms may eat at a variety of trophic levels (anchovies consume phytoplankton and zooplankton)
-Trophic level often changes with life history stage.
- Trend in a basic food pyramid : Decreasing biomass with increasing trophic level
Transfer Efficiency
The proportion of the prey production taken by predators
Transfer Efficiency Standards
o Good Transfer Efficient = 25%
o However, ~10%-15% are most fish
o Rule of thumb 10% transfer per trophic level
o More efficient to eat at base of the food web.
Limits to globals fish production
Annual primary production
PPR
Primary Productivity Required
