Post on 24-Feb-2016
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WOD 1/13/14ICONOCLAST (i KON oh klast) n. one who attacks and seeks to overthrow
traditional or popular ideas or institutions Troy’s ICONOCLASTIC views were not popular
with his parents. Young voters were attracted to the candidate’s
ICONOCLASTIC platform. Thomas Edison was a great ICONOCLAST;
without his ICONOCLASTIC views we might still be sitting in the dark.
CHAPTER 4.3: THE OCEAN’S PRIMARY PRODUCTIVITYINB Pg 44
MARINE BIOMASS The main “products” of primary production are carbohydrates.
Scientists measure primary productivity in terms of the carbon fixed (bound) into organic materials.
Biomass is the mass of living tissue. The biomass at a given time is called the standing crop. Example: The average standing crop in the oceans is 1-2 billion
metric tons. On land, the average standing crop is 600 to 1,000 billion metric tons.
MARINE BIOMASS
Comparing primary productivity of the seas to that of the land, the land’s primary production is slightly higher. How is it possible that the total primary production from
marine ecosystems is only a bit less than that of terrestrial ecosystems? – marine ecosystems cycle their energy and nutrients much more rapidly.
PLANKTON The term “plankton” does not describe
a kind of organism, but a group of organisms with a common lifestyle and habitat. Plankton include autotrophs, heterotrophs, predators and grazers. Plankton drift/swim weakly at the mercy of
water motion. Plankton are not a species, but include
many species. Most are very small, some, like the
jellyfish, grow several meters long. Some start life as planktonic larvae and
then become nektonic organisms that swim or attach themselves to the bottom as benthic organisms.
.
PLANKTON Meroplankton live part of their lives
as plankton. Holoplankton remain plankton all
their life. Phytoplankton are primary
producers responsiblefor more than 92% of marine production.
Zooplankton are primary and secondary consumersof other plankton.
PLANKTON (CONTINUED) Four most important kinds of
phytoplankton: 1. Diatoms are the most dominant and
efficientphotosynthesizers known. They convert more than 50% of the light energy
theyabsorb into carbohydrate chemical energy. They have a rigid cell wall made of silica called a frustule which admits light. This is an ideal cell material for a photosynthesizer.
2. Dinoflagellates are characterized by one or two whip-like flagella which they use to move in water. Most are autotrophs. They are the most significant
primary producers in coral reefs. They are also the principal organisms responsible for plankton blooms.
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PLANKTON (CONTINUED) Four most important kinds of
phytoplankton: 3. Coccolithophores are single-cell
autotrophs characterized by shells of calcium carbonate. They live in bright shallow water.
4. Silicoflagellates are micro-organisms with internal support structures made of silica and have one or more flagella. They are structurally and chemically more primitive
than diatoms.
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PLANKTON (CONTINUED) Understanding the role of
picoplankton has changed the way marine biologists think about tropical region productivity. Picoplankton are extremely tiny plankton. May account for up to 79% of the
photosynthesis in tropical waters. Many are cyanophytes, which are
bacteria with chlorophyll. Can also be called cyanobacteria or
blue-green algae. Their role in primary productivity is
to be food for heterotrophic bacteria. They may also play a significant role in
producing oxygen and taking up carbon dioxide.
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LIMITS ON MARINE PRIMARY PRODUCTIVITY Limiting factors are physiological or biological
necessities that restrict survival. Too much or too little of a limiting factor will reduce population.
Limiting factors in the ocean include: Inorganic nutrients such as nitrogen
and phosphorus compounds. Sunlight due to season, depth, or
water clarity.
LIMITS ON MARINE PRIMARY PRODUCTIVITY Tropical waters have low productivity.
Warm upper water act to trap nutrients in the cold layers that are too deep forphotosynthesizing autotrophs.
The Arctic and Antarctic have little temperature difference allowing nutrients to cycle to shallower water.
Temperate regions, coastal areas, have more primary productivity due to more nutrients from rain runoff. Shallow water keeps them from sinking
too deep. Areas of highest productivity are in
the Antarctic Convergence Zone and near shore temperate regions due to nutrient availability.
LIMITS ON MARINE PRIMARY PRODUCTIVITY (CONTINUED)
Light is an important limiting factor. The amount of daylight
affects photo-synthesis and primary productivity. For example, the Antarctic Convergence Zone has optimum nutrients available, seasonal sunlight limits its productivity.
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LIMITS ON MARINE PRIMARY PRODUCTIVITY (CONTINUED) Depth is a limiting factor too.
Depth affects photosynthesis and primary productivity. Suspended particles and the light’s angle limit how much light penetrates water. Even in very clear water, very little photosynthesis takes place below 100 meters (328 feet).
Too much light can be bad too. Photo-inhibition takes place when too much light overwhelms an autotroph. It cannot photo-synthesize when water is too shallow.
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LIMITS ON MARINE PRIMARY PRODUCTIVITY (CONTINUED) Different phytoplankton species
have different optimal depths. As light conditions change, the
advantage shifts from species to species.
Autotrophs produce carbohydrates and oxygen, but they also respire. They use carbohydrates and some
oxygen for respiration. The less light, the less photosynthesis and the less carbohydrates are produced.
.
LIMITS ON MARINE PRIMARY PRODUCTIVITY (CONTINUED) At some point, the amount of
carbohydrates produced exactly equals the amount requiredby the autotrophs for respiration.
The point of zero net primary production is called the compensation depth. This is the depth at which about 1%
of the surface light penetrates. If phytoplankton remain below
compensation depth, they will die within a few days.