146
C. F. HICKLING
Korringa ( 1967-8) showed vividly the importance of filter-feeding
molluscs in the accumulation of nutrient material in estuaries. Each
rising tide brings in organic matter from the sea, both dead, as detritus,
and living as plankton. The filter-feeding molluscs are very efficient
at straining off this material, which is thus trapped. After passage
through the gut of the filter-feeders, this matter may be discharged as
faecal pellets, which may become further enriched and be food material
for other organisms, through whose food-chains it is distributed
through the estuary. Korringa draws attention t o the immense number
of benthic organisms per unit surface area in some estuarine situations
(for example, as many as 1 000 cockles per m2 in the Dutch Waddenzee).
Such vast populations can only survive through the continuous accumulation of organic material brought in on flood tides. In such estuaries, the production of animal protein per square metre must rank
among the highest in the world.
Bottom-living algae, in particular, flourish on this rich material,
and the two most important fish cultivated in estuarine fishponds, the
Chanos and grey mullets, and many of the valuable penaeid prawns,
feed directly on these algae, thus telescoping the food chain to get
nutriment very economically from the base of the food pyramid.
(Hiatt, 1944).
9. Particulate organic detritus
Particulate organic detritus is a direct source of food for many
organisms. The striped grey mullet, Mugil cephalus, is believed to feed
largely on this material (Odum, 1968)) and so also is Mugil tade (Forsk.)
in India (Pillay, 1953). It is also important in England for the thicklipped grey mullet, Crenimugil labrosus (Risso), (Hickling, 1970), and
is a prime source of food for many prawns. Darnell (1967-8) was able t o
show that areas of zooplankton abundance in estuaries were correlated
with centres of detritus abundance rather than with phytoplankton
abundance.
10. Colloidal and dissolved organic material
Darnell states that many invertebrate species of differing feeding
habits are known t o be able to concentrate colloidal organic matter in
the gut, and that even some fish may be able to use this material.
Dissolved organic matter is common in sea water, and may be more
abundant even than seston. Schuster (1952) states that the Java Sea
contains 30-50 mg of organically combined phosphorus and about
50 mg of organic nitrogen per cubic metre. It is certain (Lackey, 1967-8)
that dissolved organic matter is used directly as a nutrient both by
C. F. HICKLING
Korringa ( 1967-8) showed vividly the importance of filter-feeding
molluscs in the accumulation of nutrient material in estuaries. Each
rising tide brings in organic matter from the sea, both dead, as detritus,
and living as plankton. The filter-feeding molluscs are very efficient
at straining off this material, which is thus trapped. After passage
through the gut of the filter-feeders, this matter may be discharged as
faecal pellets, which may become further enriched and be food material
for other organisms, through whose food-chains it is distributed
through the estuary. Korringa draws attention t o the immense number
of benthic organisms per unit surface area in some estuarine situations
(for example, as many as 1 000 cockles per m2 in the Dutch Waddenzee).
Such vast populations can only survive through the continuous accumulation of organic material brought in on flood tides. In such estuaries, the production of animal protein per square metre must rank
among the highest in the world.
Bottom-living algae, in particular, flourish on this rich material,
and the two most important fish cultivated in estuarine fishponds, the
Chanos and grey mullets, and many of the valuable penaeid prawns,
feed directly on these algae, thus telescoping the food chain to get
nutriment very economically from the base of the food pyramid.
(Hiatt, 1944).
9. Particulate organic detritus
Particulate organic detritus is a direct source of food for many
organisms. The striped grey mullet, Mugil cephalus, is believed to feed
largely on this material (Odum, 1968)) and so also is Mugil tade (Forsk.)
in India (Pillay, 1953). It is also important in England for the thicklipped grey mullet, Crenimugil labrosus (Risso), (Hickling, 1970), and
is a prime source of food for many prawns. Darnell (1967-8) was able t o
show that areas of zooplankton abundance in estuaries were correlated
with centres of detritus abundance rather than with phytoplankton
abundance.
10. Colloidal and dissolved organic material
Darnell states that many invertebrate species of differing feeding
habits are known t o be able to concentrate colloidal organic matter in
the gut, and that even some fish may be able to use this material.
Dissolved organic matter is common in sea water, and may be more
abundant even than seston. Schuster (1952) states that the Java Sea
contains 30-50 mg of organically combined phosphorus and about
50 mg of organic nitrogen per cubic metre. It is certain (Lackey, 1967-8)
that dissolved organic matter is used directly as a nutrient both by