PARTICULATE OKGANlC MATTER IN SEA IVATEIL
11
and deepwater samples taken off Bermuda on a more or less seasonal
basis (Riley et al., 1965). I n the first paper cited the general range in
particle number was 5-40 x 103 per litre. Lowest values were found
in the Sargasso Sea and non-upwelling tropical areas ; the highest ones
in a region of upwelling in the Guinea Current. There the number of
particles intergraded with the general range of 30-100 x lo3 per litre
which had been found in Long Island Sound.
I n all of these studies the measurements of particles size were used
in conjunction with counts to determine their total area as they
appeared on the filter in mm2/litre. This was only a crude measurement
and could not be converted into an estimate of the volume of material ;
however, a measurement of this type was regarded as a necessary
precaution against the possibility of variations in mean size of particles
from one area to another. I n this set of data the general range of values
was 6.3 to nearly 40 mm2/litre as compared with about 20-160 mm2
in Long Island Sound. From these data on numbers and areas it is
apparent that non-living particulate matter varies regionally in much
the same way that phytoplankton does, and in fact in the subtropicaltropical transect there was a correlation of 0.95 between area of particulate matter and phytoplankton cell counts. The regression equation
was
A = 0.127C + 8.0
where A = organic aggregates in mm2/litre, and C = thousands of
phytoplankton cells/litre. The form of the equation is indicative of
the fact that even when phytoplankton is scarce there will be a considerable amount of non-living particulates present. The additional
amount that is correlated with phytoplankton abundance may be
detritus derived from dead cells or it might be particles that have been
produced from extracellular metabolites. The latter point was examined
experimentally by growing cultures of seven species of diatoms and
one dinoflagellate in artificial sea water of minimal organic content
and then removing the cells and bubbling the medium. The particulate
carbon produced by the bubbling process averaged 20% of the carbon
content of the diatoms that had been removed ; however, in the case
of the dinoflagellate it was only 2y0.
Riley et al. (1965) described six sets of observations obtained on a
seasonal basis during the period from April 1963 to April 1964. Three
sets were obtained at a station about 27 km southeast of Bermuda, a
position routinely occupied by various oceanographers working at the
Bermuda Biological Station. The other three sets were cruise data
taken over a wide area and ranging between 21' and 36"N Lat.
11
and deepwater samples taken off Bermuda on a more or less seasonal
basis (Riley et al., 1965). I n the first paper cited the general range in
particle number was 5-40 x 103 per litre. Lowest values were found
in the Sargasso Sea and non-upwelling tropical areas ; the highest ones
in a region of upwelling in the Guinea Current. There the number of
particles intergraded with the general range of 30-100 x lo3 per litre
which had been found in Long Island Sound.
I n all of these studies the measurements of particles size were used
in conjunction with counts to determine their total area as they
appeared on the filter in mm2/litre. This was only a crude measurement
and could not be converted into an estimate of the volume of material ;
however, a measurement of this type was regarded as a necessary
precaution against the possibility of variations in mean size of particles
from one area to another. I n this set of data the general range of values
was 6.3 to nearly 40 mm2/litre as compared with about 20-160 mm2
in Long Island Sound. From these data on numbers and areas it is
apparent that non-living particulate matter varies regionally in much
the same way that phytoplankton does, and in fact in the subtropicaltropical transect there was a correlation of 0.95 between area of particulate matter and phytoplankton cell counts. The regression equation
was
A = 0.127C + 8.0
where A = organic aggregates in mm2/litre, and C = thousands of
phytoplankton cells/litre. The form of the equation is indicative of
the fact that even when phytoplankton is scarce there will be a considerable amount of non-living particulates present. The additional
amount that is correlated with phytoplankton abundance may be
detritus derived from dead cells or it might be particles that have been
produced from extracellular metabolites. The latter point was examined
experimentally by growing cultures of seven species of diatoms and
one dinoflagellate in artificial sea water of minimal organic content
and then removing the cells and bubbling the medium. The particulate
carbon produced by the bubbling process averaged 20% of the carbon
content of the diatoms that had been removed ; however, in the case
of the dinoflagellate it was only 2y0.
Riley et al. (1965) described six sets of observations obtained on a
seasonal basis during the period from April 1963 to April 1964. Three
sets were obtained at a station about 27 km southeast of Bermuda, a
position routinely occupied by various oceanographers working at the
Bermuda Biological Station. The other three sets were cruise data
taken over a wide area and ranging between 21' and 36"N Lat.