142
C. F. HICKLING
Organic material entering the detrital system of an estuary " represents the total gross primary and secondary production of the community, exclusive of that material which is temporarily tied up in the
protoplasm of producer, consumer, and decomposer species, and that
material which has been oxidized to the low-energy state through
respiration. Regardless of the form in which it enters the decomposition
scheme, if it is not lost to the sediments it will be subsequently broken
down to smaller sizes until it reaches the end-molecule low-energy
state " (Darnell, 1967-8). Brunelli (1937)points out that, in the brackishwaters of the Italian lagoons, stenohaline and stenothermal organisms
die, and contribute to the fertility of the soil and that the flora and
fauna of the soils of the valli are very rich in nutriment and supplement
by their abundance, the poverty of the plankton. Those eurythermal
and euryhaline organisms flourish best which feed on detritus at first
or second hand, such as the grey mullets among fish, mollusc-eaters
such as the dorade, and eaters of small insectivorous fish and chironomid larvae, such as eels. Crustacea which feed on detritus and molluscs such as the suspension feeder Cardium, are found in great
quantity. The soil abounds in shells of molluscs which assure its neutral
reaction.
Malone (1969) found that, in his Hawaiian fishpond ecosystem,
organic matter had to be imported, probably in the form of detritus,
to make good the deficiency of primary productivity over community
respiration. The organic manure given to many fishpond systems
must be effective due t o its contribution of detritus-forming material
as much as to its contribution of direct fertilizer.
4. Enrichment of detritus
Odum and de la Cruz (1967-8) found that beds of Xpartina grass in
the estuary they studied produced a rich supply of detritus. For
example, the detritus content of the water varied from only 2 mgllitre
at mid-flood tide to 20 mg/litre at mid-ebb ; detritus made up 90% to
99% of the seston, plankton playing almost no part in the fertility of
the estuarine water.
They found, that as this detritus decayed into progressively smaller
particles it became richer in protein. The fine particles had a rate of
oxygen consumption seven times greater than the large particles. The
small suspended particles of Spartina detritus contain 70~0-8070 of
ash, but of the remaining organic matter, 24% is protein reckoned on
an ash-free basis, as compared with only 10% in living Spartina, and
only 6% in newly-formed Spartina detritus. Thus, as the detritus
breaks down into smaller particles, it becomes a progressively richer
C. F. HICKLING
Organic material entering the detrital system of an estuary " represents the total gross primary and secondary production of the community, exclusive of that material which is temporarily tied up in the
protoplasm of producer, consumer, and decomposer species, and that
material which has been oxidized to the low-energy state through
respiration. Regardless of the form in which it enters the decomposition
scheme, if it is not lost to the sediments it will be subsequently broken
down to smaller sizes until it reaches the end-molecule low-energy
state " (Darnell, 1967-8). Brunelli (1937)points out that, in the brackishwaters of the Italian lagoons, stenohaline and stenothermal organisms
die, and contribute to the fertility of the soil and that the flora and
fauna of the soils of the valli are very rich in nutriment and supplement
by their abundance, the poverty of the plankton. Those eurythermal
and euryhaline organisms flourish best which feed on detritus at first
or second hand, such as the grey mullets among fish, mollusc-eaters
such as the dorade, and eaters of small insectivorous fish and chironomid larvae, such as eels. Crustacea which feed on detritus and molluscs such as the suspension feeder Cardium, are found in great
quantity. The soil abounds in shells of molluscs which assure its neutral
reaction.
Malone (1969) found that, in his Hawaiian fishpond ecosystem,
organic matter had to be imported, probably in the form of detritus,
to make good the deficiency of primary productivity over community
respiration. The organic manure given to many fishpond systems
must be effective due t o its contribution of detritus-forming material
as much as to its contribution of direct fertilizer.
4. Enrichment of detritus
Odum and de la Cruz (1967-8) found that beds of Xpartina grass in
the estuary they studied produced a rich supply of detritus. For
example, the detritus content of the water varied from only 2 mgllitre
at mid-flood tide to 20 mg/litre at mid-ebb ; detritus made up 90% to
99% of the seston, plankton playing almost no part in the fertility of
the estuarine water.
They found, that as this detritus decayed into progressively smaller
particles it became richer in protein. The fine particles had a rate of
oxygen consumption seven times greater than the large particles. The
small suspended particles of Spartina detritus contain 70~0-8070 of
ash, but of the remaining organic matter, 24% is protein reckoned on
an ash-free basis, as compared with only 10% in living Spartina, and
only 6% in newly-formed Spartina detritus. Thus, as the detritus
breaks down into smaller particles, it becomes a progressively richer