- Plant photosynthesis converts inorganic carbon of carbon dioxide into
the organic carbon of sugar, Primary productivity is the total quantity
of carbon fixed by plants, expressed as grams of carbon fixed per square
meter of sea surface per unit time (gC/m squared/yr).
- If plants are plentiful in the water of an area, animals will be plentiful.
The absence of plants means a scarcity of animals.
- Fish depend on primary production for their food; therefore fish are
more abundant in areas where primary productivity is high.
Size of Harvest
- Many of the major fisheries are being exploited at or near their maximum
sustainable yield and many are overfished.
- The U.S. National Marine Fisheries Service estimates that 45% of
the fish stocks whose status is known now suffer from
many fish have been harvested to the point that there is not enough
breeding stock left to replenish the species.
- Commercial extinction is the depletion of a resource species to a
point where it is no longer profitable to harvest.
- A substantial increase in world fisheries catch would be detrimental
to the ocean ecosystem--especially on higher carnivores (large meat-eating
fish, marine mammals, and sea birds),
- About 40% of the global fisheries catch of all species are used as
- It may be impossible to predict future fish stocks accurately (just
as it is impossible to forecast weather accurately more than a day or
two in advance).
Satellite Measurements of Chlorophyll and Phytoplankton
- When biologist at sea take water samples or do plankton tows, the measurements
are from but a small spot within the vast ocean. Other samples taken
from other locations are compared and compiled to create an overall
representation of the amount of phytoplankton available.
- Coastal Zone Color Scanners (CZCS) mounted on satellites detect different
bands of visible color emitted from the ocean's surface water. Variations
in color reflect mainly differences in the concentrations of chlorophyll,
the principal photosynthetic pigment in plants. Because chlorophyll
reflects a green light, large concentrations are indicated on the images
by green colors and sparse concentration in blue colors. This is an
indirect measure of the abundance of phytoplankton.
- Because satellites can cover Earth's oceans within a period of days,
scientists are able to get a more complete picture or measurement of