Unialgnl additions in various concentrations were used to evaluate algal supplements in both static and recirculating water system larviculture of Macrobrachium rosenbergii. Larvae were reared in 60 liter, black fiberglass, rounded bottom tanks at stocking densities ranging from 50 to 75 larvae/l. Cultures were maintained at 12 ppt synthetic seawater at 28 ± 1°C with constant light and moderate aeration. Artemia salina nauplii were used as the primary ration and fed at concentrations of 10 to 15 nauplii/ml. Fish roe (Mugil sp. and Cynoscion sp.) were used as secondary rations after day 9/10 in all cultures. Results showed that unialgal supplements, particularly those of the Chrysophyta (i.e. Isochrysis galbana, Pseudoisochrysis paradoxa, and Phaeodactylum tricornutum), significantly increased survival of larvae and production of postlarvae in both static and recirculating water systems. Mean survival was highest in recirculating algal‐supplemented cultures (82.7%) and static algal‐supplemented cultures (78.8%) and lowest in recirculating and static control cultures (50.9 and 57.0%, respectively). Post‐larval production averaged 59/1 (78% of the stocking density) in recirculating and 47/1 (74% of the stocking density) in static P. tricornutm supplemented cultures while static and recirculating controls averaged 20/1 (39%) and 32/1 (41%) respectively. Peak production of post‐larvae occurred earlier (day 28) in algal supplemented recirculating cultures than in controls (day 34) indicating that algae may also decrease length of time to metamorphosis. Survival data from all experiments were analyzed by ANOVA with regression and indicated a positive, significant relationship between algal concentration and larval survival. Periodic monitoring of nitrogenous compounds (NH4, NO2, NO3) indicated that these aspects of water quality were not directly related to the enhancement of M. rosenbergii larval culture by algal supplements.

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The value of algal supplements in rearing Macrobrachium rosenbergii larvae in static water systems was investigated. Larvae were reared in 60 liter fiberglass rounded bottom tanks at concentrations ranging from 50 to 67 larvae/liter. Standard culture methods (used by Marine Resources Research Institute) and feeds (Artemia salina nauplii, TetraMin, fish eggs) were utilized throughout the study. The three major groups of phytoplankters evaluated included the Chlorophyceae (Nannachloris oculata, Dunaliella tertiolecta, Chlorella sp.), the Chrysophyceae (Isochrysis galbana, Pseudoisochrysis paradoxa), and the Bacillariophyceae (Skeletonema costatum, Phaeodactylum tricornutum). Algal supplements were added to produce concentrations of 20,000 to 1,200,000 cells/ml in the larval culture tanks. Three replicate cultures per algal species were maintained and compared to control replicates. Algal supplements increased survival of larvae and production of postlarvae and decreased length of time to metamorphosis. P. tricornutum, I. galbana, and P. paradoxa appear to be the most valuable supplements tested to date. These treatments routinely resulted in approximately 30% greater survival and between 40 and 60% more postlarvae than control treatments. Possible mechanisms for the algal enhancement of M. rosenbergii larval culture are discussed.

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KURZFASSUNG: Verbesserung stehender und rezirkulierender Kultursysteme yon Macrobrachiura rosenbergii-Larven durch Algenzusatz. Im Rahmen eines Aquakulturvorhabens wurde gepriifi, inwieweit sich die Gegenwart der Diatomee Phaeodactylum tricornutum auf die Zucht der Garnele Macrobrachium rosenbergii (DE MAN) auswirkt. Als Nahrung ffir die Larven yon M. rosenbergii dienten in den Versuchsreihen (12 %0 S, 28-+-1 ° C, Dauerlicht) Nauplien von Artemia salina und ab 9. Lebenstag zus~itzliche Gaben yon Mugil-Rogen. Verglichen mit den Kontrollreihen bewirkte die Gegenwart der Diatomeen (340 000 Zellen/ml) eine signifikant erh6hte r0berlebensrate der Larven, und zwar sowohl in stehenden als auch in rezirkulierenden Kultureinheiten. Zudem erreichte eine gr~flere Anzahl von Individuen das Postiarvalstadium, wobei auch die Metamorphose friiher als bei den algenfrei geziichteten Kontrolltieren einsetzte. Wasser&emische Untersuchungen zeigten, daft die verbesserten Zuchterfolge nicht von den gemessenen Konzentrationen der Endprodukte des Sti&stoffwechsels (NH4 +, NO2-, NOa-) ab-h~ingig waren.