n conspicuous effect below salinities of 24.6-27-2%, in P . martensii, while
Yuiki (1951) and Kobayashi and Matsui (1953) demonstrated that the
effects on the ciliary activities of the gills were conspicuous below
salinities of 20.0 and 22.6%, respectively.
Suspended solids
The quantities of suspended matter contained in the surrounding
water may be one of the leading factors influencing faecal and pseudofaecal production in suspeiision feeders. I n P . martensii, Ota (1959)
demonstrated that, during summer and autumn, the variation of the
total amounts of faeces and pseudofaeces is essentially similar to that
o f the amounts of suspended matter per unit volume of the surrounding
water. Lund (1957) obtained similar results to Ota and found that
faecal and pseudofaecal production positively correlated with materials
(ground Ulva) added to water flowing over oysters. While on the other
hand, Haven and Morales-Alamo (1 966) demonstrated in C. virginica
that there was no correlation between quantities of faeces collected
daily with those of seston, whereas pseudofaeces were positively correlated with seston when temperatures were at mid-range but not
during the warmest period in midsummer Similar results to those were
also obtained by Loosanoff and Engle (1947) who pointed out that
pseudofaeces were approximately proportional to the concentration of
added materials (Chlorella suspensions), whereas the rate of faecal
discharge decreased as the concentrations increased. The reasons for
this wide difference are unexplained, but, as suggested by Haven and
Morales-Alamo (1966), it is likely that the bivalves were not able to
filter all the available organic matter and that a portion occurred as
particles too small to be filtered from suspension.
Size of producer
In the course of the study on the seasonal variations of faecal
and pseudofaecal production of P. martensii, it was shown by Ota
(1959) that the smaller the size of the animal, the larger the faecal and
pseudofaecal production per unit weight of the producer became,
though quantities of faeces and pseudofaeces were approximately proportional to the size of the animal. Haven and Morales-Alamo (1966)
obtained similar results in C. virginica and found that there are
positive correlations between faecal and pseudofaecal production and
the weight of the producer.
Other factors
Ota (1959a) showed that the post-operative shock resulting from
operations of nuclear insertion for cultured pearl oyters had a great
Yuiki (1951) and Kobayashi and Matsui (1953) demonstrated that the
effects on the ciliary activities of the gills were conspicuous below
salinities of 20.0 and 22.6%, respectively.
Suspended solids
The quantities of suspended matter contained in the surrounding
water may be one of the leading factors influencing faecal and pseudofaecal production in suspeiision feeders. I n P . martensii, Ota (1959)
demonstrated that, during summer and autumn, the variation of the
total amounts of faeces and pseudofaeces is essentially similar to that
o f the amounts of suspended matter per unit volume of the surrounding
water. Lund (1957) obtained similar results to Ota and found that
faecal and pseudofaecal production positively correlated with materials
(ground Ulva) added to water flowing over oysters. While on the other
hand, Haven and Morales-Alamo (1 966) demonstrated in C. virginica
that there was no correlation between quantities of faeces collected
daily with those of seston, whereas pseudofaeces were positively correlated with seston when temperatures were at mid-range but not
during the warmest period in midsummer Similar results to those were
also obtained by Loosanoff and Engle (1947) who pointed out that
pseudofaeces were approximately proportional to the concentration of
added materials (Chlorella suspensions), whereas the rate of faecal
discharge decreased as the concentrations increased. The reasons for
this wide difference are unexplained, but, as suggested by Haven and
Morales-Alamo (1966), it is likely that the bivalves were not able to
filter all the available organic matter and that a portion occurred as
particles too small to be filtered from suspension.
Size of producer
In the course of the study on the seasonal variations of faecal
and pseudofaecal production of P. martensii, it was shown by Ota
(1959) that the smaller the size of the animal, the larger the faecal and
pseudofaecal production per unit weight of the producer became,
though quantities of faeces and pseudofaeces were approximately proportional to the size of the animal. Haven and Morales-Alamo (1966)
obtained similar results in C. virginica and found that there are
positive correlations between faecal and pseudofaecal production and
the weight of the producer.
Other factors
Ota (1959a) showed that the post-operative shock resulting from
operations of nuclear insertion for cultured pearl oyters had a great