144
C . F. HICKLING
without the application of fertilizer other than organic matter such as
leaf trash, or even with no fertilizer a t all.
5. The further breakdown of detritus
Thus the detritus improves as a foodstuff as it is broken down by
such agencies as mastication and digestion by animals, mechanical
grinding by the soil which would release enzymes €or autolysis, and
the chemical effects of saprophytic bacteria and fungi.
Sub-particulate organic detritus includes colloids, aggregates of
large molecules such as proteins, carbohydrates, fats etc. ; smaller molecules can exist, such as vitamins, amino-acids, sugars, urea, or as dissolved gases, methane, ammonia, H,S. All these represent some
potential energy for species able to exploit them. It is worth noting
that urea has proved t o be a successful fertilizer for blue-green algae.
It can be seen therefore that detritus represents potential energy,
originally accumulated by photosynthesis. It may have been formed
in the estuary itself (autochthonous sources) or have been brought in
from outside the estuary (allochthonous sources) (Darnell, 1967-8).
6. Autochthonous sources
(a) Detritus derived from the death of phytoplankton which has
flourished in the estuary. Ketchum (1967-8) cites the case of a very
dense population of small Chlorophyceae produced by the discharge of
duck manure into an estuary. The further growth of this population
was inhibited by its own turbidity and by a lack of available nitrogen.
These plants would die and add to the stock of detritus.
(b) Detritus derived from submerged vegetation and from mud-$at
diatoms and jilamentous algae. These may be very abundant ; whole
areas may be carpeted with algae, which again may carry a coating
of epiphytes. These algal pastures are the principal food for both
Chams and grey mullet. I n fish culture one of the chief arts is the care
and fostering of this algal pasture. Any surplus to current needs, with
the faecal matter from fish and other organisms which have fed on this
algal pasture, breaks down into detritus which still contains much of
the original potential energy.
(c) Periphyton growing on surfaces. Odum (1968) confirms the findings of Newel1 (1 965) that small particles of whatever origin “ are far
from being poor inert bodies, but are flourishing micro-ecosystems
containing bacteria, protozoa, and microalgae. To a great extent, the
smaller the particle, the greater its relative food value.”
C . F. HICKLING
without the application of fertilizer other than organic matter such as
leaf trash, or even with no fertilizer a t all.
5. The further breakdown of detritus
Thus the detritus improves as a foodstuff as it is broken down by
such agencies as mastication and digestion by animals, mechanical
grinding by the soil which would release enzymes €or autolysis, and
the chemical effects of saprophytic bacteria and fungi.
Sub-particulate organic detritus includes colloids, aggregates of
large molecules such as proteins, carbohydrates, fats etc. ; smaller molecules can exist, such as vitamins, amino-acids, sugars, urea, or as dissolved gases, methane, ammonia, H,S. All these represent some
potential energy for species able to exploit them. It is worth noting
that urea has proved t o be a successful fertilizer for blue-green algae.
It can be seen therefore that detritus represents potential energy,
originally accumulated by photosynthesis. It may have been formed
in the estuary itself (autochthonous sources) or have been brought in
from outside the estuary (allochthonous sources) (Darnell, 1967-8).
6. Autochthonous sources
(a) Detritus derived from the death of phytoplankton which has
flourished in the estuary. Ketchum (1967-8) cites the case of a very
dense population of small Chlorophyceae produced by the discharge of
duck manure into an estuary. The further growth of this population
was inhibited by its own turbidity and by a lack of available nitrogen.
These plants would die and add to the stock of detritus.
(b) Detritus derived from submerged vegetation and from mud-$at
diatoms and jilamentous algae. These may be very abundant ; whole
areas may be carpeted with algae, which again may carry a coating
of epiphytes. These algal pastures are the principal food for both
Chams and grey mullet. I n fish culture one of the chief arts is the care
and fostering of this algal pasture. Any surplus to current needs, with
the faecal matter from fish and other organisms which have fed on this
algal pasture, breaks down into detritus which still contains much of
the original potential energy.
(c) Periphyton growing on surfaces. Odum (1968) confirms the findings of Newel1 (1 965) that small particles of whatever origin “ are far
from being poor inert bodies, but are flourishing micro-ecosystems
containing bacteria, protozoa, and microalgae. To a great extent, the
smaller the particle, the greater its relative food value.”