Solution B
Dissolve in 1 liter of distilled water
NaN03
150.0 g
*NH,Cl
50.0 g
Ferric sequestrine
10.0 g
* Mociia for Isockyxiu gulbunu shociltl omit the NH,CI.
Experiments conducted at our laboratory have shown that some
species of bacteria are harmless, others are strongly pathogenic, and
still others produce toxic metabolites. It is quite possible, therefore,
for some bacterized cultures of algae to be good larval foods, while
the same algae, with a different bacterial population, may be acutely
toxic. Consequently, for critical evaluation of any phytoplankton
organism as a food for larvae it is necessary to use a bacteria-free
culture of it. Furthermore, in using mass cultures of algae, where there
is always danger of bacterial contamination, it should always be ascertained that the cultures have not become contaminated with toxic
o r p t hopwic: 1)nctmia.
As already mentioned, certain species of algae also produce metabolites that are toxic to bivalve larvae, while other species produce
little or none (Fig. 23). Some of the algae produce so much toxic
material that they are useless as foods because their toxins kill
larvae even when concentration of algal cells is too light to satisfy
larval demand for food. Others, such as Chlorella (580), produce
some toxic products but are still usable foods, provided that their
concentrations are not too high.
Recently, Davis (1953) and Davis and Cjuillard (1958) concluded
that presence and thickness of cc:ll walla t i r i d dngrtu: fd frtxic:it,,y of
metabolites are important factors in determining uarthility of jdiotosynthetic microorganisms as larval food. 7'hcy Rhowed that tht: m k ~ d
flagellates, I . gulbana and M . Zutheri, were of apjmxirnetcly qud
value as food for larvae of the American oyster and inducc:d marc
rapid growth than any of the other species tested. Davis also believw
that I . gulbuna and M . Zutheri produce little, if any, toxic external
metabolites which unfavorably affect Iarvac:. This is supported by his
ot)sc:rvntions that thcb optimal conccntrationr;l of the two formS for
either clam or oyster larvae wore a t lcast tloublt: the optirnul coricentratiom of Chlorelkz RP. (Lewin's isolate).
The food value of microorganifima also tlopend~, in part, upon how
for i > x i m p l v , t I I I L ~ , IL misf i i r ~ ot' I . p r / / ) ( i / / u , M . h t h ~ r i ,
f'l~ikrl~/mo~~as sp.
aiitl 1)uncrliolLr vuchloru iiitluccd morc rapid growth of both clam
(.ornplc.ltdy tht1.V I I I W ~ , t h foot1 ~ . c ~ ( l ~ i i ~ . c . r n c . ~ ~ t , q
of IIL~VIU!. It, w w ~ O I I I I ~ ,
Dissolve in 1 liter of distilled water
NaN03
150.0 g
*NH,Cl
50.0 g
Ferric sequestrine
10.0 g
* Mociia for Isockyxiu gulbunu shociltl omit the NH,CI.
Experiments conducted at our laboratory have shown that some
species of bacteria are harmless, others are strongly pathogenic, and
still others produce toxic metabolites. It is quite possible, therefore,
for some bacterized cultures of algae to be good larval foods, while
the same algae, with a different bacterial population, may be acutely
toxic. Consequently, for critical evaluation of any phytoplankton
organism as a food for larvae it is necessary to use a bacteria-free
culture of it. Furthermore, in using mass cultures of algae, where there
is always danger of bacterial contamination, it should always be ascertained that the cultures have not become contaminated with toxic
o r p t hopwic: 1)nctmia.
As already mentioned, certain species of algae also produce metabolites that are toxic to bivalve larvae, while other species produce
little or none (Fig. 23). Some of the algae produce so much toxic
material that they are useless as foods because their toxins kill
larvae even when concentration of algal cells is too light to satisfy
larval demand for food. Others, such as Chlorella (580), produce
some toxic products but are still usable foods, provided that their
concentrations are not too high.
Recently, Davis (1953) and Davis and Cjuillard (1958) concluded
that presence and thickness of cc:ll walla t i r i d dngrtu: fd frtxic:it,,y of
metabolites are important factors in determining uarthility of jdiotosynthetic microorganisms as larval food. 7'hcy Rhowed that tht: m k ~ d
flagellates, I . gulbana and M . Zutheri, were of apjmxirnetcly qud
value as food for larvae of the American oyster and inducc:d marc
rapid growth than any of the other species tested. Davis also believw
that I . gulbuna and M . Zutheri produce little, if any, toxic external
metabolites which unfavorably affect Iarvac:. This is supported by his
ot)sc:rvntions that thcb optimal conccntrationr;l of the two formS for
either clam or oyster larvae wore a t lcast tloublt: the optirnul coricentratiom of Chlorelkz RP. (Lewin's isolate).
The food value of microorganifima also tlopend~, in part, upon how
for i > x i m p l v , t I I I L ~ , IL misf i i r ~ ot' I . p r / / ) ( i / / u , M . h t h ~ r i ,
f'l~ikrl~/mo~~as sp.
aiitl 1)uncrliolLr vuchloru iiitluccd morc rapid growth of both clam
(.ornplc.ltdy tht1.V I I I W ~ , t h foot1 ~ . c ~ ( l ~ i i ~ . c . r n c . ~ ~ t , q
of IIL~VIU!. It, w w ~ O I I I I ~ ,