In order to conduct experiments on interactions between animals and food organisms, it is necessary to develop a medium that adequately supports the growth of both algae and zooplankton without the need to alter the medium to accommodate either the algae or the animals. We devised a freshwater medium, named COMBO, that supports excellent growth of both algae and zooplankton. Two types of algae, Ankistrodesmus falcatus and Stephanodiscus hantzschii, were reared in COMBO and their growth rates were not significantly different from those of algae grown in a reference medium (WC). One of these algae, A. falcatus, was then fed to a cladoceran, Daphnia pulicaria, which was also cultured in COMBO, and the resulting fecundities of D. pulicaria were compared to those of animals reared in natural surface water. We also determined whether the value of COMBO as a medium for D. pulicaria was affected by modifications in nitrogen or phosphorus concentration to evaluate whether the new medium will be useful in nutritional research. Lowering the N or P content of COMBO did not affect the reproductive performance of D. pulicaria. Other researchers have also reported excellent growth and reproduction by numerous algae and zooplankton reared in COMBO. Our results suggest that COMBO is an effective artificial, defined culture medium capable of supporting robust growth and reproduction of both freshwater algae and zooplankton.

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COMBO: a defined freshwater culture medium for algae and zooplankton

Field data and laboratory feeding experiments support the hypothesis that predation can be an important factor in the adaptive significance of vertical migration among zooplankton. In both Gatun Lake in Panama and Fuller Pond in Connecticut the diel vertical migration patterns of prey populations assume distributions which result in lessened predation by the dominant lake planktivores. It is concluded that such patterns of vertical migration will result when prey populations are under intense, selective pressures from visually dependent predators.

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1976.21.6.0804

Vertical migration in zooplankton as a predator avoidance mechanism1

Organisms differ in the proportions of major elements that they contain, including N and P, which are known to be highly dynamic and potentially limiting to production of aquatic ecosystems. Such contrasting elemental composition between, for example, algae and herbivores, or between different herbivores, generates a suite of ecological predictions and opens up new dynamical possibilities. Here we review studies relating to the nutritional physiology of aquatic herbivores, especially freshwater pelagic species, and we relate element content to secondary production and nutrient recycling. A variety of evidence from many types of studies-physiological modelling, whole-ecosystem surveys, laboratory growth studies, etc-is assembled into an internally consistent picture of mineral limitation of aquatic herbivores. Herbivores with high nutrient demands (the best example is probably Daphnia and phosphorus) appear frequently to be limited not by the food quantity or energy available to them but by the quantity of mineral elements in their food.

Algal nutrient limitation and the nutrition of aquatic herbivores

ADaM, an artificial freshwater for the culture of zooplankton

4 – Functional Aspects of Nutrition and Digestion

1. Artemia salina can be grown aseptically to adults in a non-living medium.2. The components of the medium are: sea water, Trypticase, liver infusion, hydrolysed RNA and DNA, serum, sucrose, cholesterol, paramecium factor, glutathione, a mixture of B vitamins, and starch particles.3. Glutathione, thiamine, and folic acid were found essential even in the presence of Trypticase and serum. Glutathione can be replaced by cysteine. Horse or beef serum (Difco) supply unidentified heat-stable nutrients. Cholesterol and mixtures of fatty acids become rapidly toxic, and do not replace serum.4. Artemia is a voracious particle feeder and transforms the starch particles rapidly into fecal pellets. In the absence of starch particles, the liquid part of the medium, though containing all the nutrients. supports growth only to the third-stage metanauplii. This indicates that the rate of ingestion (swallowing) of liquids is too low to support continuous growth and that the particles are necessary to increase the swallowi...

Axenic cultivation of the brine shrimp artemia salina

1. The 1959 undefined artificial medium for Artemia was simplified to a medium containing only defined ingredients: a liquid phase containing mineral salts, 6 amino acids, 5 nucleic acid components, 8 vitamins, 2 sugars, a pH buffer, and a fine particulate phase consisting of precipitated albumin, gelled rice starch, and cholesterol. The amino acids and sugars are dispensible.2. Starch and albumin were not replaceable by their soluble components (sugar and amino acids) even in the presence of inert or absorbing particles. Phagotrophy appeared the most efficient way to satisfy the bulk nutritional requirements.3. Growth rate and differentiation depended upon starch: protein ratio and total quantity of particles.4. Artemia ingested liquids but apparently to a very limited extent since vitamins and nucleic acid components (nontoxic even at very high concentrations) were utilized as solutes only when in high concentrations. Amino acid mixtures on the other hand became toxic at concentrations too low to satisf...

Development of artificial media for artemia salina

1. Moina macrocopa was cultured aseptically for more than 200 parthogenetic generations in a nearly-defined medium without losing fertility.2. A biphasic medium was used. The liquid phase supplied minerals, B-vitamins, amino acids, liver infusion and nucleic acids. The fine particulate phase consisted of egg albumin, albumin fraction V, starch and lipid factors.3. The particulate phase was essential for rapid growth, taking advantage of the food gathering efficiency of filter feeders.4. Developmental time, brood size and sustained fertility depended on calciferol, tocopherol and saturated and unsaturated fatty acids; B carotene or retinol favored fertility but might not be essential.5. Moina was found to require cholesterol, nucleic caids, thiamine, nicotinamide, pyridoxine, Ca pantothenate and probably riboflavin and folic acid in the presence of liver infusion, the only undefined and required component of the medium.6. Ratios and quantities of the nutrients were important for media efficiency: excess vi...

Nutritional requirements of the water flea moina macrocopa

1. Daphnia magna can be grown for at least 200 generations, axenically or in crude cultures, in a defined mineral medium, enriched with vitamin B12 and thiamine and 1 ml/100 of a dilute organic medium, when fed with Chlamydomonas reinhardi and Scenedesmus obliquus.2. The organic enrichment is essential for maintaining continued fertility of D. magna.3. The organic enrichment can be replaced by the addition of pantothenic acid to vitamin B12 and thiamine without lowering the fertility of D. magna.4. The organic enrichment (or the vitamin mixture) does not act directly on D. magna but via the algae by changing their nutritional value for Daphina.5. Addition of vitamins to the medium in which the algal food is grown with crustacea may allow continuous cultures of herbivorous crustacea which are considered difficult to grow.

Dixenic culture of Daphnia magna, Straus.

1. Two tetraploid strains of Artemia salina were axenized. The bisexual strain from the Great Salt Lake was obtained bacteria-free by serial washes of the wintering eggs in Merthiolate. The parthenogenetic strain from the Comacchio salines was axenized by serial washes of gravid females and nauplii in antibiotics; the yeast infection was eliminated by high salinity.2. Methods for the maintenance of the bacteria-free stocks were defined. Various phytoflagellates were found suitable food organisms for both strains of Artemia when grown in appropriately enriched sea water.3. Two species of Dunaliella were adapted to grow in synthetic salt solutions ranging from 0.5 to 20.5% total salts. These conditions permitted the study of the effect of salinity on egg production of Artemia in diaxenic culture.4. Great Salt Lake Artemia grown at various salinities, in inorganic enrichments and fed ad libitum with salinity-adapted D. viridis and D. salina, failed to deposit eggs in solutions containing less than 3% salts. ...

Luigi Provasoli

Papers

Axenic cultivation of the brine shrimp artemia salina

Development of artificial media for artemia salina

Nutritional requirements of the water flea moina macrocopa

Dixenic culture of Daphnia magna, Straus.

Effects of salinity and nutrients on mono- and diaxenic cultures of two strains of artemia salina