PARTICULATE ORQANIC MATTER I N SEA WATER
51
transformed into materials that look like pale primordia of the aggregates found in nature. I n short, the writer suspects that the equilibrium
condition is a dynamic steady state rather than a static situation.
Otsuki (1968) has described the formation of aggregates in fresh
water during the course of bacterial utilization of dissolved organic
matter produced by addition of dried algae of the genus Scenedesmus.
There are photographs of these aggregates in the paper, and they are
indistinguishable from the marine material that has been described.
I n one experiment of 185 days’ duration the dissolved organic carbon
decreased from 213 to 87.1 mg/litre, due to the combined effects of
bacterial utilization and conversion of dissolved to particulate carbon,
but no estimate was made of the amount of particulate carbon formed.
There was a concomitant decrease in the carbon : nitrogen ratio from
11.1 to 5.9 (atoms). Similar decreases in C : N ratios were noted in many
other decomposition experiments.
Parsons and Seki (1968) have described aggsegation phenomena in
both filtered and unfiltered sea water. They mentioned having seen
several different kinds of particles, but special attention was focused
on clumping of bacteria. The size of the clumps was of the order of 4 p,
more or less, and these authors apparently felt that the clumps consisted primarily of bacterial biomass although there was a suggestion
of cementing action by excreted polymers together with inclusions of
other materials.
The writer is aware of this clumping phenomenon, but again this
appears to be a stage in the production of larger aggregates in which
the major part of the organic matter is non-living. Admittedly the
early stages in the development of aggregates are not very noticeable
without the aid of staining procedures, and they are so delicate that
they may be broken up during Coulter Counter measurements.
Two special cases of in situ aggregate formation are mentioned in
passing. Sieburth and Jensen (1968) described extracellular production
of organic matter by Pucus and other littoral brown algae, and they
found that some of the end products of decomposition of the exudates
condensed into organic aggregates. The authors described this material
as “ polyphenol tanned carbohydrate and proteinaceous material ”. A
second example was reported by Johannes (1967), who found a marked
increase in organic aggregates in shallow water passing over an atoll
reef. The aggregates apparently were formed from mucus secreted by
the corals; however, this probably was a result of fragmentation of
pre-existing materials rather than in s i t u condensation from smaller
particles or dissolved substance. Hence the example is not quite
comparable with other studies that are being reviewed in this section.
51
transformed into materials that look like pale primordia of the aggregates found in nature. I n short, the writer suspects that the equilibrium
condition is a dynamic steady state rather than a static situation.
Otsuki (1968) has described the formation of aggregates in fresh
water during the course of bacterial utilization of dissolved organic
matter produced by addition of dried algae of the genus Scenedesmus.
There are photographs of these aggregates in the paper, and they are
indistinguishable from the marine material that has been described.
I n one experiment of 185 days’ duration the dissolved organic carbon
decreased from 213 to 87.1 mg/litre, due to the combined effects of
bacterial utilization and conversion of dissolved to particulate carbon,
but no estimate was made of the amount of particulate carbon formed.
There was a concomitant decrease in the carbon : nitrogen ratio from
11.1 to 5.9 (atoms). Similar decreases in C : N ratios were noted in many
other decomposition experiments.
Parsons and Seki (1968) have described aggsegation phenomena in
both filtered and unfiltered sea water. They mentioned having seen
several different kinds of particles, but special attention was focused
on clumping of bacteria. The size of the clumps was of the order of 4 p,
more or less, and these authors apparently felt that the clumps consisted primarily of bacterial biomass although there was a suggestion
of cementing action by excreted polymers together with inclusions of
other materials.
The writer is aware of this clumping phenomenon, but again this
appears to be a stage in the production of larger aggregates in which
the major part of the organic matter is non-living. Admittedly the
early stages in the development of aggregates are not very noticeable
without the aid of staining procedures, and they are so delicate that
they may be broken up during Coulter Counter measurements.
Two special cases of in situ aggregate formation are mentioned in
passing. Sieburth and Jensen (1968) described extracellular production
of organic matter by Pucus and other littoral brown algae, and they
found that some of the end products of decomposition of the exudates
condensed into organic aggregates. The authors described this material
as “ polyphenol tanned carbohydrate and proteinaceous material ”. A
second example was reported by Johannes (1967), who found a marked
increase in organic aggregates in shallow water passing over an atoll
reef. The aggregates apparently were formed from mucus secreted by
the corals; however, this probably was a result of fragmentation of
pre-existing materials rather than in s i t u condensation from smaller
particles or dissolved substance. Hence the example is not quite
comparable with other studies that are being reviewed in this section.