What are seaweeds? What are the classifications of seaweeds? What ...

[Yolanda]

What are seaweeds? What are the classifications of seaweeds? What will be an ideal response?

Question 2

What are the disadvantages of using biomass as a means to calculate primary productivity? What are
  some other means used to measure this productivity? What will be an ideal response?

[mohan]

Answer to Question 1

ANS:Answer
should include:
 Seaweeds are nonvascular, photosynthetic organisms. They are a type of algae. They
share similar structures to leaves, stems, and roots. Many thrive in temperature, nutrientrich
waters.
 There are two categories of seaweedsphaeophytes and rhodophytes. They are
classified by their accessory pigments.
 Phaeophytes are brown algae. Nearly all living species are marine. These include the
largest of algae, kelp. Some of the phaeophytes are seasonal. Some are able to grow in
water 35 meters deep. Phaeophytes dominate in temperate and subpolar regions.
 Rhodophytes are red algae. This classification group contains most species of seaweeds.
There are more rhodophyte species than other algae groups combined.

Answer to Question 2

ANS:Answer
should include:
 Biomass, or mass of living tissue, present in an area is directly proportional to
productivity. The problem with using this method in the ocean is that dense populations
of autotrophs interfere with the amount of light penetration. The decrease in light
penetration means autotrophs produce carbohydrates at a slower rate. This is no longer a
direct proportion to productivity.
 In areas of small autotroph populations, there can be more light penetration. This would
cause there to be a higher rate of primary productivity.
 Researchers have tagged carbon radioactively. Carbon-14 behaves in the same way
Carbon-12 does during photosynthesis. This allows the researchers to measure
productivity directly.
 Productivity can be measured by using light-dark bottle techniques. Two samples are
collected, one is placed in each bottle. They are placed at a buoy. The light bottle
receives sunlight while the opaque blocks the light. The difference in carbon uptake can
then be calculated.
 Orbiting satellites are starting to be used in determining productivity. They can estimate
the chlorophyll content of an area. This is directly related to photosynthesis.

[Yolanda]

Excellent

[gcook]

Thanks for the timely response, appreciate it