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.