The combined effects of temperature and salinity on hatching performance of three anostracan species, Phallocryptus spinosa, Branchinecta orientalis and Streptocephalus torvicornis from East and West Azerbaijan, Iran, were studied. The cysts were kept for 10 days at seven different temperatures (12, 15, 18, 21, 24, 27 and 30°C) and four salinity conditions (0, 5, 10, and 15 gL) and the effects of the resulting 28 experimental conditions on hatching patterns (duration of pre-hatching period, hatching percentage at first day of hatching, cumulative hatching success) were examined. Results were tested by ANOVA and multiple regression was applied to generate contour models by polynomial equation. The hatching performance in all species was significantly affected by temperature and salinity.
Based on contour plot analysis, maximum hatching for P. spinosa, B. orientalis and S. torvicornis cysts was registered at temperatures 19-25ºC, 18-23ºC and 16-20ºC, respectively, within the same salinity range of 0-1 gL–1 The highest cumulative hatching success among the species was observed in P. spinosa at the combination of 24°C and 0gL–1(88. 98%). No hatching was observed for eggs of S. torvicornis and B. orientalis incubated at lower (<15ºC) and higher (>27ºC) temperature, respectively. The pre-hatching period was prolonged with increase in salinity and decrease in temperature and was highest in P. spinosa (7.7 days at 12°C and 15 gL salinity).
High hatching success was observed over wide ranges of temperature and salinity in P. spinosa eggs which demonstrates one of the possible mechanisms responsible for the wide distribution of this species
The variable quality and high price of Artemia (Leach 1819) cyst products, used worldwide as live food, motivate aquaculturists to find an appropriate alternative, especially for fresh/brackish water organisms. In this study, Branchinecta orientalis (G. O. Sars 1901), a common fairy shrimp in north‐western Iran, was reared for 15 days using effluent from trout ponds enriched with effluent filtrate as sole feed, or co‐fed with microalgae (Scenedesmus sp.). The effluent filtrate was replaced by algae at different ratios (25% and 50%), and feeding experiments were designed at densities of 100, 200 and 400 individuals/L in 3‐L containers and at 100 individuals/L in 20‐L containers. The results indicated that, at a certain density, the final length and survival were not significantly affected by different feeding regimes (p > .05). In 3‐L containers, the highest length and survival were observed at the lowest density. B. orientalis contained the highest amounts of proteins, carbohydrates and lipids, though, when co‐fed algae, although the differences with the treatment fed solely effluent filtrate were often limited. Inclusion of algae in the diet also resulted in higher levels of a number of PUFAs. Our study proves that B. orientalis can be mass‐cultured successfully using trout effluent as culture medium without additional microalgae. Fish pond effluent is massively available as a cheap food source. Recycling aquaculture effluent for this type of live food production contributes to lowering the use of natural resources and to less discharge of nutrient loads into natural water bodies.
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