REARINU O F BIVALVE MOLLUSKS
37
We have used a variety of containers to culture larvae. Some of
them were large glass vessels, including Downing and McDonald jars
used in fish hatcheries for incubation of semi-buoyant eggs, lobster
jars, 5-gal earthenware jars, and 76-gal polyethylene and Fiberglas
containers. We have also grown larvae in large, outdoor, concrete
tanks containing several thousand liters of sea water (Loosanoff, 1954).
In all these instances the larvae were grown successfully.
For precise experimental work Pyrex glass beakers of 1000- to
1500-ml capacity are perhaps the most satisfactory because they are
not toxic and are readily cleaned and sterilized (Fig. 5). Polyethylene
and other plastic containers are also convenient and non-breakable
and some can be sterilized. However, some of them are permeable to
certain insecticides and, perhaps, to other substances and are known
to adsorb a variety of toxins. Because of these considerations polyethylene and some other plastic containers, while convenient as culture
vessels, cannot be used in experiments involving certain toxic substances, such as insecticides.
New, soft glass vessels may contain substances which are toxic
to eggs or larvae of oysters and clams. Even though these vessels are
conditioned in sea water for Reveral days, culturing larvae in them is
always haphazard because, although larvae in different vessels are
presumably grown under identical conditions, their rates of growth are
often distinctly different and they show mortalities unrelated to the
treatment. A t the same time sibling larvae grown in earthenware jarsor
Pyrex glass containers suffer no mortality and different cultures receiving the same treatment show good duplication in their rate of growth.
Although we could not identify the substances responsible for p o o r
growth of larvae gro;wn in soft glass jars, we found, nevertheless, that
young bivalve larva, especially those of C. virginica, are sensitive to
presence in the water of e&n minute quantities of certain chemicals.
For example, we noticed that washing of glassware and other implements with tap wa'ter that passed through a pipeline containing
copper unfavorably affected larval development. Apparently, even
minute quantities of these metals are sufficient to interfere with normal
development of eggs and larvae.
Our experience in growing bivalve larvae has ehown that they
cannot be kept in recently-built concrete tanks and that, usually, it is
necessary to age the tanks with sea water for a long time before this
can be done.
Since most of our studies are quantitative, as well as qualitative,
definite numbers of eggs or larvae per ml of culture are needed from
the start. This is achieved in the following manner: eggs are placed
37
We have used a variety of containers to culture larvae. Some of
them were large glass vessels, including Downing and McDonald jars
used in fish hatcheries for incubation of semi-buoyant eggs, lobster
jars, 5-gal earthenware jars, and 76-gal polyethylene and Fiberglas
containers. We have also grown larvae in large, outdoor, concrete
tanks containing several thousand liters of sea water (Loosanoff, 1954).
In all these instances the larvae were grown successfully.
For precise experimental work Pyrex glass beakers of 1000- to
1500-ml capacity are perhaps the most satisfactory because they are
not toxic and are readily cleaned and sterilized (Fig. 5). Polyethylene
and other plastic containers are also convenient and non-breakable
and some can be sterilized. However, some of them are permeable to
certain insecticides and, perhaps, to other substances and are known
to adsorb a variety of toxins. Because of these considerations polyethylene and some other plastic containers, while convenient as culture
vessels, cannot be used in experiments involving certain toxic substances, such as insecticides.
New, soft glass vessels may contain substances which are toxic
to eggs or larvae of oysters and clams. Even though these vessels are
conditioned in sea water for Reveral days, culturing larvae in them is
always haphazard because, although larvae in different vessels are
presumably grown under identical conditions, their rates of growth are
often distinctly different and they show mortalities unrelated to the
treatment. A t the same time sibling larvae grown in earthenware jarsor
Pyrex glass containers suffer no mortality and different cultures receiving the same treatment show good duplication in their rate of growth.
Although we could not identify the substances responsible for p o o r
growth of larvae gro;wn in soft glass jars, we found, nevertheless, that
young bivalve larva, especially those of C. virginica, are sensitive to
presence in the water of e&n minute quantities of certain chemicals.
For example, we noticed that washing of glassware and other implements with tap wa'ter that passed through a pipeline containing
copper unfavorably affected larval development. Apparently, even
minute quantities of these metals are sufficient to interfere with normal
development of eggs and larvae.
Our experience in growing bivalve larvae has ehown that they
cannot be kept in recently-built concrete tanks and that, usually, it is
necessary to age the tanks with sea water for a long time before this
can be done.
Since most of our studies are quantitative, as well as qualitative,
definite numbers of eggs or larvae per ml of culture are needed from
the start. This is achieved in the following manner: eggs are placed