76
VICTOR L. LOOSANOFF A N D HARRY C. DAVIS
size have also been found severely infected. On many occasions hundreds of thousands of young clams of this size were found dead or dying
within a day or two after the first signs of infection were noticed.
Our observations indicate that fungus is introduced into larval
cultures with untreated sea water or, perhaps, more often with food
organisms, such as phytoplankton grown in our outdoor tank in which
the media is not sterilized. It may be the same organism that infects
and kills small crustaceans, such &s copepods, which are sometimes
present in our outdoor cultures of phytoplankton.
8
A
D
C
FIG. 26. Larvae infested with fungi. A and B, young larvae of Crassostrea VitginiCa
stained with Neutral Red ; C, young larvae of Mercenuria mercenaria stained with
Neutral Red; D, old larvae of Mercenarka memenaria stained with Cotton Blue.
x 225.
In seeking a method to control fungus infections in our larva1
cultures we studied the effects Gf many fungicides, including most of
those used in fish hatcheries. So far, not a single promising compound
has been found. As a rule, the chemicals unfavorably affected the
larvae at coneentrations lower than those at which the fungus wae
affected. However, precautionary measures, consisting largely in
maintaining a general cleanliness of all utensils coming in contact with
larvae and in using germicidal ultraviolet rays to treat all water,
gave promising results. Plankton food, if it comes from impure rn-
VICTOR L. LOOSANOFF A N D HARRY C. DAVIS
size have also been found severely infected. On many occasions hundreds of thousands of young clams of this size were found dead or dying
within a day or two after the first signs of infection were noticed.
Our observations indicate that fungus is introduced into larval
cultures with untreated sea water or, perhaps, more often with food
organisms, such as phytoplankton grown in our outdoor tank in which
the media is not sterilized. It may be the same organism that infects
and kills small crustaceans, such &s copepods, which are sometimes
present in our outdoor cultures of phytoplankton.
8
A
D
C
FIG. 26. Larvae infested with fungi. A and B, young larvae of Crassostrea VitginiCa
stained with Neutral Red ; C, young larvae of Mercenuria mercenaria stained with
Neutral Red; D, old larvae of Mercenarka memenaria stained with Cotton Blue.
x 225.
In seeking a method to control fungus infections in our larva1
cultures we studied the effects Gf many fungicides, including most of
those used in fish hatcheries. So far, not a single promising compound
has been found. As a rule, the chemicals unfavorably affected the
larvae at coneentrations lower than those at which the fungus wae
affected. However, precautionary measures, consisting largely in
maintaining a general cleanliness of all utensils coming in contact with
larvae and in using germicidal ultraviolet rays to treat all water,
gave promising results. Plankton food, if it comes from impure rn-