10
GORDON A. RILEY
origin and composition, but their appearance is not distinctive enough
to encourage attempts t o classify them.
2. Seasonal cycles in inshore waters
Riley (1963) described a two-year study of particulate matter in
Long Island Sound based largely on counts and measurements of
particles. The results were quite similar to earlier work by Krey (1961)
whose examination of the seasonal cycle in the Kiel Bight consisted
mostly of protein analyses and seston weights.
The following generalizations apply to both surveys : the level of
non-living particulate matter was moderately high in midwinter, when
the quantity of phytoplankton was small. It increased further to a
peak that more or less coincided with the peak of the spring diatom
flowering and thence declined to the lowest point of the year at about
the time of the termination of the flowering. The quantity was relatively
small during most of the summer and autumn. The only major difference in the two seasonal cycles was an early summer peak in Long
Island Sound, a period of the year when the quantity was low at Kiel.
Within the traditional view that non-living organic matter consists
mainly of detritus derived from the death of organisms, certain aspects
of these results would be puzzling. Lower values would be expected
during the midwinter period of phytoplankton poverty, and increases
associated with phytoplankton flowerings should be most pronounced
during the terminal stages of the flowering rather than near the peak.
However, these new developments cast another light on the problem. An increase coincident with the flowering would be expected if
extracellular metabolites could be converted to particles, and mixing
processes associated with winter storms might have been responsible
for the observed increase in particulate matter during early winter.
There was some evidence to support these hypotheses. The number
of flakes was larger in winter than in summer, and the yield of particles
obtained by bubbling filtered sea water more or less followed the
seasonal trend of naturally occurring seston during winter and spring.
However, in the absence of any really good methods for determining
rates of particle production in nature such hypotheses remain speculatory.
3. Particle counts in offshore waters
The methods developed for counting and measuring particulate
matter were subsequently applied to a series of surface collections
obtained on a transect from the Sargasso Sea south of Bermuda to the
coast of Africa at about SON (Riley et al., 1964) and a series of surface
GORDON A. RILEY
origin and composition, but their appearance is not distinctive enough
to encourage attempts t o classify them.
2. Seasonal cycles in inshore waters
Riley (1963) described a two-year study of particulate matter in
Long Island Sound based largely on counts and measurements of
particles. The results were quite similar to earlier work by Krey (1961)
whose examination of the seasonal cycle in the Kiel Bight consisted
mostly of protein analyses and seston weights.
The following generalizations apply to both surveys : the level of
non-living particulate matter was moderately high in midwinter, when
the quantity of phytoplankton was small. It increased further to a
peak that more or less coincided with the peak of the spring diatom
flowering and thence declined to the lowest point of the year at about
the time of the termination of the flowering. The quantity was relatively
small during most of the summer and autumn. The only major difference in the two seasonal cycles was an early summer peak in Long
Island Sound, a period of the year when the quantity was low at Kiel.
Within the traditional view that non-living organic matter consists
mainly of detritus derived from the death of organisms, certain aspects
of these results would be puzzling. Lower values would be expected
during the midwinter period of phytoplankton poverty, and increases
associated with phytoplankton flowerings should be most pronounced
during the terminal stages of the flowering rather than near the peak.
However, these new developments cast another light on the problem. An increase coincident with the flowering would be expected if
extracellular metabolites could be converted to particles, and mixing
processes associated with winter storms might have been responsible
for the observed increase in particulate matter during early winter.
There was some evidence to support these hypotheses. The number
of flakes was larger in winter than in summer, and the yield of particles
obtained by bubbling filtered sea water more or less followed the
seasonal trend of naturally occurring seston during winter and spring.
However, in the absence of any really good methods for determining
rates of particle production in nature such hypotheses remain speculatory.
3. Particle counts in offshore waters
The methods developed for counting and measuring particulate
matter were subsequently applied to a series of surface collections
obtained on a transect from the Sargasso Sea south of Bermuda to the
coast of Africa at about SON (Riley et al., 1964) and a series of surface