L13 Flashcards
What is primary production
Primary production is the total amount of carbon (C) in grams that is converted into organic material per square meter of sea surface per year (gC/m2/yr).
What factors limit plant growth and reduce primary production
Factors that limit plant growth and reduce primary production include solar radiation and nutrients as major factors and upwelling, turbulence, grazing intensity, and turbidity as secondary factors.
How much incoming solar radiation is employed for photosynthesis and stored as energy in organic compounds
0.1-0.2%
What is net primary productivity
Net primary productivity is the amount of carbon converted into organic material above that required for the minimal survival of the autotroph. It is the amount of organic material available for growth and reproduction.
What is compensation depth and at what depth does it typically occur
Compensation depth is the depth where net primary productivity equals zero. This is usually located where light intensity is about 1 percent of its surface value, which typically occurs at a water depth of ~110 meters in clear water
At what temperatures is productivity in the ocean negligible
Productivity is negligible when water temperatures are colder than 0o and warmer than 40o. Between these limits, productivity increases with increasing temperature.
what happens to most of the light entering the ocean
d. Most of the light entering the ocean is absorbed and converted into heat.
why does productivity increase with latitude
productivity tends to increase with latitude because of the greater availability of nutrients away from the equator.
what are macronutrients
Macronutrients are elements or compounds required in large quantities, particularly phosphorus (P), nitrogen (N), and silicon (Si).
what macronutrients do phytoplankton require and in what ratio
c. Phytoplankton generally require phosphorus (P), nitrogen (N), and carbon (C) in the ratio of 116C:16N:1P.
what are micronutrients
Micronutrients are indispensable elements and compounds used in very small quantities. Because they are needed in small (trace) eg iron copper, manganese, zinc, boron and colbat
how to scarcity of macronutrients typically occur
The scarcity of macronutrients typically occurs over a broad region of the ocean and so limits productivity on a regional scale.
is carbon abundant in sea water
yes so it is never a limiting factor
are nitrogen and phosphorus abundant
they are needed in smaller amounts but due to their demand are less abundant
what is usually the limiting factor in productivity
nitrogen
what can silicon be a limiting factor to (2) and why
diatoms and silicaflagellates they need silicon to construct their shells
how is nutrients from dead organisms released
d. Dead organisms and waste material sink into the deeper water, removing the nutrients they contain from the productive surface zone. Decomposition eventually releases the nutrients into the deep water.
4. Upwelling and turbulence can return nutrients to the surface.
what is upwelling
Upwelling is the slow, persistent rising of nutrient-rich water toward the ocean surface
give 3 examples of upwelling
-In equatorial waters between the gyres, because Ekman transport causes surface water to diverge, inducing water from below to rise to the surface.
- In coastal waters where persistent wind produces seaward Ekman transport of surface water, thereby promoting upwelling of water.
- Nearshore turbulence generated by storm waves and tidal currents mix nutrient-rich waters upward. This is most pronounced wherever the seafloor is irregular and coastal currents are strong.
.
what can the overgrazing of autotrophes lead to
can deplete the population and lead to a decline in productivity
how does turbidity restrict productivity
turbidity reduces the depth of light penetration and restricts productivity even if nutrients are abundant.
what is productivity like in the tropics and subtropics
- In the tropics and subtropics, sunlight is abundant, but it generates a strong thermocline that restricts upwelling of nutrients and results in lower productivity. High productivity can occur locally in areas of upwelling between the circulation gyres and at coral reefs.
what is productivity like in temperate regions
- In temperate regions, productivity is distinctly seasonal.
what is productivity like in temperate regions winter
In winter, the water column is isothermal and mixes easily, and although nutrients are abundant at the surface, limited sunlight restricts productivity.
what is productivity like in temperate region spring
In spring, sunlight becomes more abundant, which triggers a diatom bloom.
what is productivity like in temperate region summer
- A thermocline develops and prevents vertical mixing and resupply of nutrients.
- Usage depletes the nutrients in the surface water.
- Grazing by herbivores greatly reduces the population of phytoplankton.
what is productivity like in temperate region autumn
In the fall, productivity initially increases as the water becomes isothermal and nutrients again become abundant, but then declines as sunlight diminishes.
what range does primary productivity range from:
25 to 1,250 gC/m2/yr
what is primary productivity like in the open ocean
In the open ocean, the distribution of productivity resembles a “bull’s-eye” pattern with the lowest productivity located in the center, the highest at the edge of the basin. Water in the open ocean is colored blue because of downwelling, the presence of a permanent strong, deep thermocline, and the near-absence of plankton.
what is primary productivity like on the continental shelves
Continental shelves display moderate biological productivity of between 50 and 200 gC/m2/yr, because nutrients wash in from the land and tide- and wave-generated turbulence recycle nutrients from the bottom water.
what is primary productivity like in polar areas
Polar areas have high biological productivity because there is no pycnocline to inhibit mixing.
what is primary productivity like in equatorial waters
Equatorial waters have high biological productivity in areas of upwelling and low productivity elsewhere because of the presence of a sharp pycnocline
what does the word trophic refer to
nutrition
what are trophic dynamics
- Trophic dynamics is the study of the nutritional interconnections among organisms in an ecosystem.
what is the formula for photosynthesis
6CO2 + 6H2O + sunlight C6H12O6 (sugar) + 6O2
what is the formula for respiration
C6H12O6 (sugar) + 6O2 6CO2 + 6H2O + energy
Basic feeding style: grazers
a. Grazers—consume plant material.
Basic feeding style:predators
b. Predators—hunt and kill prey.
Basic feeding style:scavengers
c. Scavengers—consume dead organic matter.
Basic feeding style:filter feeders
d. Filter feeders—filter the water for suspended food.
Basic feeding style: deposit feeders
e. Deposit feeders—selectively or nonselectively consume food that is mixed in the sediments.
what type of feeder is bacteria
decomposer
what are the two basic types of bacteria
Aerobic bacteria—require free oxygen to respire and decompose dead matter.
Anaerobic bacteria—live in an oxygen-free (anoxic) environment, but obtain oxygen for respiration from other sources, such as SO42– (sulfate ion) and release H2S (hydrogen sulfide gas) as a byproduct of decay
what are the two types of autotroph bacteria
Cyanobacteria (blue-green algae) photosynthesize.
b. Chemosynthetic bacteria use chemical energy released in the oxidation of inorganic compounds to produce food.
on average how much energy is passed between trophic levels
10-20%
