SCATOLOGICAL STUDIES OF THE BIVALVIA (MOLLUSCA)
419
included under the term " biodeposition " (Haven and MoralesAlamo, 1966).
In this Section, reviews and discussions about the principal features
of this pioneering work done within comparatively recent years will be
presented.
A. Factors injluencing hiodeposition
A number of environmental factors are known that influence the
rate of defecation of the suspension feeding bivalves. From the data
of Korringa (1952), Jorgensen (1965) and others, Haven and MoralesAlamo (1966) pointed out that the amounts of faeces or pseudofaeces
produced by filter-feeders are determined by the physiological responses
of the animals to environmental stimuli, and that particle filtration is
the most important of these responses which may depend on particle
size and concentration, algal species, temperature, salinity and other
characteristics of the surrounding water.
Temperature
Discharge of faecal matter takes place only within certain temperature limits. In Pinctada martensii (Gmelin), Ota (1959) ascertained experimentally that the optimum temperature for the rates of
faecal and pseudofaecal discharge range from 27.0 to 29.5OC and the
discharge of faeces is impaired or stopped when the temperature falls
below lO"C, while in Crassostrea virginica (Gmel.), Haven and MoralesAlamo (1966) stated that at temperatures lower than 2.8"C measurable
quantities of faeces and pseudofaeces were not produced and that when
temperature decreased to 6.7"C there was an 850/, decrease in weight of
faeces and pseudofaeces. Loosanoff (1958) found that at temperatures
between 2.0 and 3-0"C, 1.1% of 90 oysters producedfaeces and only 15%
produced pseudofaeces. Ito and Imai (1955) stated that, when kept in
water at 9°C and with poor suspension of food, a single oyster (C. gigas)
weighing 90 g produced a minimum of 0.03 g faeces (dry weight) daily.
Galtsoff (1964) showed that the average rate of discharge of faecal ribbons in actively feeding oysters, C. virginica, in laboratory sea-water at
temperatures of 154-15-7"C was 8-1 cm in length/h and he estimated
that the time of passage of food through the entire alimentary tract was
95 min. According to Ota (1959) the time of passage of food in P. martensii observed ranged from 4+ to 10 h or more according to the water
temperature (29-5-15.5"C) during the summer season.
Sabinit y
The effect of the low salinity on the rate of faecal and pseudofaecal production was shown by Ota and Fukushima (1961), who found
419
included under the term " biodeposition " (Haven and MoralesAlamo, 1966).
In this Section, reviews and discussions about the principal features
of this pioneering work done within comparatively recent years will be
presented.
A. Factors injluencing hiodeposition
A number of environmental factors are known that influence the
rate of defecation of the suspension feeding bivalves. From the data
of Korringa (1952), Jorgensen (1965) and others, Haven and MoralesAlamo (1966) pointed out that the amounts of faeces or pseudofaeces
produced by filter-feeders are determined by the physiological responses
of the animals to environmental stimuli, and that particle filtration is
the most important of these responses which may depend on particle
size and concentration, algal species, temperature, salinity and other
characteristics of the surrounding water.
Temperature
Discharge of faecal matter takes place only within certain temperature limits. In Pinctada martensii (Gmelin), Ota (1959) ascertained experimentally that the optimum temperature for the rates of
faecal and pseudofaecal discharge range from 27.0 to 29.5OC and the
discharge of faeces is impaired or stopped when the temperature falls
below lO"C, while in Crassostrea virginica (Gmel.), Haven and MoralesAlamo (1966) stated that at temperatures lower than 2.8"C measurable
quantities of faeces and pseudofaeces were not produced and that when
temperature decreased to 6.7"C there was an 850/, decrease in weight of
faeces and pseudofaeces. Loosanoff (1958) found that at temperatures
between 2.0 and 3-0"C, 1.1% of 90 oysters producedfaeces and only 15%
produced pseudofaeces. Ito and Imai (1955) stated that, when kept in
water at 9°C and with poor suspension of food, a single oyster (C. gigas)
weighing 90 g produced a minimum of 0.03 g faeces (dry weight) daily.
Galtsoff (1964) showed that the average rate of discharge of faecal ribbons in actively feeding oysters, C. virginica, in laboratory sea-water at
temperatures of 154-15-7"C was 8-1 cm in length/h and he estimated
that the time of passage of food through the entire alimentary tract was
95 min. According to Ota (1959) the time of passage of food in P. martensii observed ranged from 4+ to 10 h or more according to the water
temperature (29-5-15.5"C) during the summer season.
Sabinit y
The effect of the low salinity on the rate of faecal and pseudofaecal production was shown by Ota and Fukushima (1961), who found