The impact of salinity, temperature, feed type and feed concentration on reproductive rate ‘r’ of Brachionus calyciflorus were examined in the present study. Three salinity levels (0.5%, 5.0% and 10.0%) and three temperature regimes (25 ± 1 oC, 29 ± 1 oC and 35 ± 1 oC) were evaluated. Four microalgal diets, Chlorella ellipsoidea, Ankistrodesmus convolutes, Scenedesmus protuberans and Chlorococcum infusorium at a concentration of 1x 106, 2x 106, 3x 106, 4x 106, 6x 106, 8x 106, 10x 106 and 12x 106 were tested in the experiment. The findings showed that all these parameters have significant influence on reproductive potential of Brachionus calyciflorus. The optimum salinity and temperature required for rmax for B. calyciflorus were of 0.5% and 29 ± 1 oC, respectively. The intrinsic rate of reproduction of B. calyciflorus for the best salinity x feed concentration with C. ellipsoidea (8 x 106 cell mL-1), A. convolutus (6 x 106 cells mL-1), C. infusorium (8 x 106 cells mL-1) and S. protuberans (4 x 106cells mL-1 ) at the optimal salinity and temperature were 1.91, 1.83, 1.77 and 1.62. Based on the study, the maximum reproductive potential of B. calyciflorus can be achieved by feeding with C. ellipsoidea at a salinity and temperature of 0.5% and 29 ± 1 oC, respectively for the larviculture of fishes.

https://www.fisheriesjournal.com/archives/2016/vol4issue4/PartC/4-2-25-860.pdf

Reproductive rate of Brachionus calyciflorus under the influence of salinity, temperature, feed type and feed concentration

The effects of both algae components and densities on the formation of resting eggs of freshwater rotifer,Brachionus calyciflorus, obtained by hatching the resting eggs in sediment from Lake Donghu and culturing clonally in March, 1998, were studied using population accumulative culture method, under the conditions of temperature 25±1℃, intensity of illumination 300 lx and illumination period L∶D=16∶8. Two species of algae, Chlorella pyrenoidosa and Scenedesmus obliquus were cultured by the method of Li Shanghao's . The results showed that the resting eggs were produced mainly during the initial six days of the culture. At the food density of 01 mg/ml, the production and efficiency of formation of resting eggs of the rotifers fed Sobliquus or mixed algae of 1∶1 mixture (wet weight) of S.obliquus and C.pyrenoidosa were 71245±6514 ind/(10ml6d) and 11874±1084 ind/mg diet, or 58400±14820 ind/(10ml6d) and 9733±2470 ind/ mg diet, respectively.Rotifers fed C.pyrenoidosa produced significantly more eggs: 1643333±401040 ind/(10ml6d) and 2739±668 ind/mg diet, respectively.The remarkable increases of mixis rate in the populations and mean number of resting eggs produced by a resting eggproducing mictic female were also observed.But there was no significant difference of fertilization rate among the rotifers fed three types of diet. Using C.pyrenoidosa as the rotifers' food, with the increase of food density the production of resting eggs increased very significantly, but the efficiency of resting egg formation decreased very significantly.The relationship between the production of resting egg [y, ind/(10ml6d)] and the algae food density (x, ×107cell/ml) fitted to the equation: y=78524-5929x.

Effect of both algae components and densities on the formation of resting eggs of the freshwater rotifer,brachionus calycifloru

Natural populations of planktonic rotifers are affected by salinity and food density, among other stressors. Moreover, competition among congeneric species limits the abundance of certain rotifers in ecosystems without spatial heterogeneity and environmental fluctuations. We isolated Brachionus plicatilis and Brachionus calyciflorus from Salado River basin waterbodies and studied the demographic characteristics and competition between them at three salinity levels (0.75, 1.75 and 2.75gL–1 NaCl) and at two food concentrations (0.1×106 and 0.5×106 cells mL–1 Chlorella vulgaris). The lowest salinity level proved to be unfavourable for the population growth of B. plicatilis, but at higher salinity levels the growth was similar to that of controls (without competition), even in the presence of the competitor and at either food concentration. By contrast, the competitor almost always decreased the density of B. calyciflorus. Salinity greatly affected the peak density of B. plicatilis, whereas the effects of salinity and competition on B. calyciflorus were similar. Biomass was inversely related to salinity for both species, and was significantly affected by competition in B. plicatilis. These results show that B. calyciflorus is more adversely affected than B. plicatilis by competition and high salinity, and explain why both species can coexist in eutrophic saline lowland rivers and pampean shallow lakes.

Effect of salinity and food concentration on competition between Brachionus plicatilis Müller, 1786 and Brachionus calyciflorus Pallas, 1776 (Rotifera)

Rotatoria (=Rotifera) belonging to the smallest metazoa consist of 1000 species of which 90% inhabit in
freshwater habitats. In the fifties and sixties though Brachionus plicatilis was first identified as a pest in the pond
culture of eels but soon the Japanese researchers realized that this rotifer could be used as a suitable live food
organism for the early larval stages of marine fish. Later in China also B. plicatilis is used as food in local shrimp and
crab hatcheries. The rotifers are considered as an important live feed in hatchery operation due to their planktonic
nature, tolerance to a wide range of environmental conditions, high reproduction rate (0.7-1.4 offspring/female/day),
small size and slow swimming nature. The animals reproduce rapidly and can thus contribute to the build up of large
quantities of live food in a very short period of time. The possibility of rearing these animals at very high densities (2000
animals/ml ) have been reported by (Hirata, 1979) and the growth is assured by plasma increase and not by cell
division. More over the filter-feeding nature of the rotifers facilitates the inclusion of specific nutrients essential for the
larval predators through bioencapsulation into their body tissues.

Culture of rotifer and their nutritional enrichment- Winter School on Recent Advances in Breeding and Larviculture of Marine Finfish and Shellfish

The characteristics of life history of rotifer Brachionus calyciflorus collected respectively from Lake Tingtang in Wuhu City and Lake Liwan in Guangzhou City in winter,which was cultured at three statuses of temperatures (10℃,15℃ and 20℃) with 3.0×106cells/ml of alga Scenedesmus obliquus as their food,was studied by means of life-table demography. The results showed that,at 10℃ all the life-table demographic parameters of Wuhu population,except for the intrinsic rate of population growth,were larger than those of Guangzhou population. At 15℃,only the generation time and the proportion of sexual offspring of Wuhu population were larger than those of Guangzhou population. At 20℃,both the generation time and the proportion of sexual offspring of Wuhu population were larger than those of Guangzhou population,but the reverse were also true for the gross reproductive rate,the net reproductive rate and the intrinsic rate of population growth. With the rise of temperature,the life expectancy at hatching,the generation time and the mean lifespan of the two geographic populations of B. calyciflorus decreased,and the intrinsic rate of population increased,but the rates of decrease or increase were different between the two geographic populations. The gross reproductive rate and the net reproductive rate of Wuhu population were both not significantly affected by the temperatures. However,the gross reproductive rate of Guangzhou population gradually increased with increasing temperature,and the net reproductive rates at 20℃ and 15℃ were similar and higher than that at 10℃. The proportion of sexual offspring of Wuhu population at 10℃ was higher than that 20℃,but both of them were similar to that at 15℃. The proportion of sexual offspring of Guangzhou population increased with increasing temperature. The differences in the intrinsic rate of population growth between the two geographic populations might be attributed to their long-term adaptation to the annually mean temperatures,but that in the proportion of sexual offspring between them might result from their long-term adaptation to the seasonal variations of temperatures in their aquatic habitats.

Life history characteristics of rotifer Brachionus calyciflorus from two lakes situated in different geographic regions

The impact of salinity, temperature, feed type and feed concentration on reproductive rate ‘r’ of Brachionus angularis were examined in the present study. Three salinity levels (0.5%, 5.0% and 10.0%), three temperature regimes (25±1 o C, 29±1 o C and 35±1 o C) and four microalgal diets, Chlorella ellipsoidea, Ankistrodesmus convolutes, Scenedesmus protuberans and Chlorococcum infusorium at a concentration of 1x 10 6 , 2x 10 6 , 3x 10 6 , 4x 10 6 , 6x 10 6 , 8x 10 6 , 10x 10 6 and 12x 10 6 were tested in the experiment. The findings showed that all these parameters have significant influence on reproductive potential of B. angularis. The optimum salinity and temperature required for highest ‘r’ were 0.5% and 28.0 o C, respectively. The intrinsic rate of reproduction ‘r’ of B. angularis for the best salinity x feed concentration with C. ellipsoidea (4x10 6 cells mL -1 ), A. convolutus (3 x 10 6 cells mL -1 ), S. protuberans (1 x 106 cells mL-1), and C. infusorium (4x106 cells mL-1) at the optimal temperature were 1.74, 1.57, 0.92 and 1.56. Based on the study, the maximum reproductive potential of B. angularis can be achieved by feeding with C. ellipsoidea at a salinity and temperature of 0.5% and 29 ± 1 o C, respectively, which is useful for larviculture of fishes.

https://www.faunajournal.com/archives/2016/vol3issue1/PartA/2-5-19.pdf

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Papers

Reproductive rate of Brachionus calyciflorus under the influence of salinity, temperature, feed type and feed concentration

Effects of salinity, temperature, feed type and feed concentration on the reproductive rate of Brachionus angularis