1 Dr. Craig Kasper, HCC Aquaculture Program Zooplankton CultureDr. Craig Kasper, HCC Aquaculture Program
2 Last Time: What’s a LUX??A unit of illumination equal to the direct illumination on a surface that is everywhere one meter from a uniform point source of one candle intensity or equal to one lumen per square meter called also meter-candlea unit of illumination, equivalent to foot-candle and equal to the illumination produced by luminous flux of one lumen falling perpendicularly on a surface one meter square. Symbol: lx
3 IntroductionZooplankton is required as a first food for many cultured fish; for others it contributes to faster growth and higher survival.Since larval fish don’t take up much space, acre ponds will do nicely, if you are outdoors. Indoor fry culture can be done in gallon tanks in a recirculation system.Tiny fry eat tiny prey, but are preyed upon by manycreatures bigger than they are.Stock the right size fry and feed the right size zooplankton! Yes, some zooplankton would try to eat your fry.
5 First Feeding on Zooplankton Most fish fry eat three main types of zooplankton—rotifers, copepods and cladocerans.For the tiniest fish fry, HSB or WB, small rotifers may bethe only zooplankton small enough to eat.If fry are too large, then they rotifers may not provide enough nutrition.Copepod nauplii, which arejust-hatched copepods, are important first foods for larval fish, too.
7 Rotifers Rotifer (0.04 -2.5 mm long). Sim. to microalgae. “Wheel organ” a ring of ciliathat “rotates” around the mouthAppear early, hatch from “resting eggs”in the pond reproduced rapidly(2-8 days post hatch).Asexual reproduction: need good conditionsSexual reproduction: poor pond conditions(“resting” eggs produced)
9 Rotifers Hexarthra, note the egg attached to this female Floscularia, tube building rotifer,attaches to plant stems.
10 Rotifer Setup Sterilized water (whether salt or fresh) pH and temperature should = starter culture.Temperature is ° CpH 8.0Start with at least rotifers/ml (minimizes crashing)1-2 feedings per day; continuous preferable.
11 Counting… Counts determine health* *Healthy cultures of rotifers contain egg bearing females and very few males. An increase in the number of male rotifers, easily identifiable by their smaller size, is an indicator of a stressed culture (bad H20 quality).female rotifer w/eggsSedgwick-Rafter Cells with Grid
12 Hatching Rotifers SW “L” Type - Brachionus plicatilis 200-360μ “S” Type - Brachionus rotundiformis μ“SS” Type - Brachionus rotundiformis μFW Brachionus rubens, Brachionus calciflorusTemperature: 30°CpH:Feed: Nannochloropsis (algae)Feeding Rate: 15 ml of Nanno/10 million "L" type/day Feeding Times/Day: Continuous, or every 3 hours
14 Copepod Artemia nauplii Next copepods to appear from resting eggs.Artemia molt up to 12 times before reaching adult stages (provides an increasing food size for larval fish.)Adults may reach 3 mm length
15 Hatching Requirements Good water.Clean clean equipment, tubing hatching contianer, etc.pH: 8.5Illumination: constant bright lightTemperature: 24-28°Aeration: needed to keep Artemia cysts circulating.Salinity: recommended to be approximately 24-28ppt.Density of cysts should not exceed 10 grams / liter.Incubation Time: usually hatch out takes approximately 24 hours.
16 Cladocerans (Water Fleas) Cladocerans: third major groupLarger fry and even adults eat them.Cladocerans 2 to 3mm long are commonly found in culture ponds several weeks after the ponds are filled.Hatch from resting eggs.Cladocerans compete with rotifers and calanoidcopepods for phytoplankton.
20 Culture Parameters Salinity - 99% of Cladocerans are freshwater Oxygen - Tolerant of low oxygen. A slow aeration is needed. Aggressive bubbles kill them (Bio-foam filters work great!)pHHardness: D. magna tends to prefer harder water (170 mg carbonate hardness) and D. pulex a little less hard (90 mg carbonate hardness).Temperature: Daphnia magna 18-22°C (64-72°F)D. pulex > 10°C.Moina °C (41-88° F); opt °C (75-88°F).Food: Green water, yeasts, bacteriaOther facts: <0.5 ppm P stimulates reproduction, but concentrations higher than 1.0 are lethal to the young.