FAUNA AND FLORA O F MANGROVE SWAMPS
217
It was this occurrence of larger individuals of different colour
patterns that led Estampador ( 1 949) to seek for specific differences, so
that he recognized three species using cytogenetic characters as his
main distinguishing features. No subsequent author except Serene
(1 952) has recognized these differences. Furthermore Estampador's
cytological work appears to be rather uncritical.
I n Queensland, Stephenson and Campbell (1960) record that after
spates in the rivers large numbers of Scylla appear off river mouths as
though they had been washed down by the increased flow of fresh
water-or perhaps the dilution of water in the burrows had made them
leave and then be carried passively downstream to a more suitable
salinity. A similar occurrence has been noted a t the mouths of the
Keiskama and Kowie rivers in the south-eastern Cape Province of
South Africa (Macnae, unpublished data).
More work is certainly necessary on this most delectable of the
edible crabs and one on which some important, if local, fisheries depend.
Hall (1961) has stated that mangrove areas are important feeding
grounds for penaeid prawns in Malaya and Singapore. I n western
Malaya and along the Straits of Malacca this is probably always true,
for almost the entire coastline is mangrove-clad. But on other shores
the statement needs modification. De Freitas (personal communication)
has shown that the penaeid prawns found and fished in the Bay of
Lourengo Marques fall into two groups: ( 1 ) those such as juvenile
Penaeus japonicus Bate which are caught in beach seines off sandy
beaches with no mangroves, and ( 2 ) those which are caught in set traps
off shores in front of mangroves. These catches invariably include
various sizes of P. indicus H.M.-Edw. and of Metapenaeus monoceros
H.M.-Edw. and occasionally large specimens, often very large specimens, of P. monodon Fabr. and of P. semisulcatus de Haan, but never
small specimens of these. Since these prawns are caught on moonless
nights after a spring tide in traps set across the drainage channels of the
shore, the inference is that these prawns are migrating back to deeper
water after a spell within the mangrove or on the shore in front of the
mangroves above the traps. Since the prawns enter a t full tide the fish
ponds of Java and elsewhere one may presume that they enter the
mangal and that they feed there. But insufficient is known of the
biology of penaeid prawns to make any but tentative statements.
3. iklollusca
mangal.
g. Penaeid prawns
Representatives of only a few families of molluscs have invaded the
Of gastropods two families only are well represented: the
217
It was this occurrence of larger individuals of different colour
patterns that led Estampador ( 1 949) to seek for specific differences, so
that he recognized three species using cytogenetic characters as his
main distinguishing features. No subsequent author except Serene
(1 952) has recognized these differences. Furthermore Estampador's
cytological work appears to be rather uncritical.
I n Queensland, Stephenson and Campbell (1960) record that after
spates in the rivers large numbers of Scylla appear off river mouths as
though they had been washed down by the increased flow of fresh
water-or perhaps the dilution of water in the burrows had made them
leave and then be carried passively downstream to a more suitable
salinity. A similar occurrence has been noted a t the mouths of the
Keiskama and Kowie rivers in the south-eastern Cape Province of
South Africa (Macnae, unpublished data).
More work is certainly necessary on this most delectable of the
edible crabs and one on which some important, if local, fisheries depend.
Hall (1961) has stated that mangrove areas are important feeding
grounds for penaeid prawns in Malaya and Singapore. I n western
Malaya and along the Straits of Malacca this is probably always true,
for almost the entire coastline is mangrove-clad. But on other shores
the statement needs modification. De Freitas (personal communication)
has shown that the penaeid prawns found and fished in the Bay of
Lourengo Marques fall into two groups: ( 1 ) those such as juvenile
Penaeus japonicus Bate which are caught in beach seines off sandy
beaches with no mangroves, and ( 2 ) those which are caught in set traps
off shores in front of mangroves. These catches invariably include
various sizes of P. indicus H.M.-Edw. and of Metapenaeus monoceros
H.M.-Edw. and occasionally large specimens, often very large specimens, of P. monodon Fabr. and of P. semisulcatus de Haan, but never
small specimens of these. Since these prawns are caught on moonless
nights after a spring tide in traps set across the drainage channels of the
shore, the inference is that these prawns are migrating back to deeper
water after a spell within the mangrove or on the shore in front of the
mangroves above the traps. Since the prawns enter a t full tide the fish
ponds of Java and elsewhere one may presume that they enter the
mangal and that they feed there. But insufficient is known of the
biology of penaeid prawns to make any but tentative statements.
3. iklollusca
mangal.
g. Penaeid prawns
Representatives of only a few families of molluscs have invaded the
Of gastropods two families only are well represented: the