Population Growth of Six Iranian Brachionus Rotifer Strains in Response to Salinity and Food Type

Abstract

Intrinsic rates of population increase (r) were evaluated as a measure of population dynamics of four strains of Brachionus plicatilis and two strains of B. urceolaris from Iran in response to different salinities and feeding algae. Each rotifer strain was cultured at four salinities: 5, 20, 25 and 30‰ and fed with two microalgal species: Chlorella vulgaris and Nannochloropsis oculata. Salinity of 5‰ was critical for all the examined strains, at which r was at minimum and was different from the other salinities (P < 0.05). For B. plicatilis strains, the maximum r was observed in those fed on Chlorella at salinities of 10 and 30‰ (64 ± 0.01 day −1). While, in B. urceolaris, maximum r was for Nannochloropsis fed rotifers at salinity of 20‰ (0.69 ± 0.01 day −1). Maximum final population density (FD) was obtained for a strain of B. urceolaris fed on Nannochloropsis at 20‰ (329.3 ± 10.9 ind.mL −1). FD was relatively lower in B. plicatilis strains among all examined salinities. ANOVA showed the significant effect of salinity and rotifer strain, and algae × rotifer strain on both r and FD, and salinity × rotifer × algae on FD (P < 0.05). IntroductionRotifers are considered as ideal model organisms for various kinds of biological laboratory studies including population dynamics (YOSHINAGA et al., 1999;SARMA, 2006;SNELL and DESROSIERS, 2008). They have also become a valuable and, in many cases, indispensable food organism for first feeding of a large variety of cultured marine finfish and crustacean larvae (DOUILLET, 2000).Success in rotifer culture seems, to a great extent, to be dependent on providing adequate information on the life history characteristics and environmental preferences of each biotype. An increasing number of studies have been carried out on the effects of salinity, temperature and the type and concentration of food on the demographic traits and population growth of rotifers (CABRERA et al., 1993;OLTRA and TODOLI, 1997;FIELDER et al., 2000;SARMA and NANDINI, 2002;ATHIBAI and SANOAMUANG, 2008). These studies were accomplished using several rotifer species (XI et al., 2001;SUCHAR and CHIGBU, 2006;WULLUR et al., 2009

Inhibitory Effects of Antipsychotic Chlorpromazine on the Survival, Reproduction and Population Growth Other Than Neurotransmitters of Zooplankton in Light of Global Warming

“…Life table experiments on rotifers are common in environmental risk assessment, ecological and aquaculture research [ 61 ]. At all temperatures, there was no significant difference in T at 0.125 mg/L CPZ treatments compared to the control in the current study.…”

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“…However, strains of the same species with different geographic origins can have different biological characteristics and environmental requirements as a result of different genetic backgrounds (Yin & Zhao, 2008;Malekzadeh-Viayeh et al, 2010); thus, it is important to evaluate the potential for growth of the different native strains recently identified. For example, it has been found that salinity affects the lifetime, the reproduction mode and the growth rate of rotifers of the genus Brachionus (Bosque, Hernández, Pérez, Todolí, & Oltra, 2001;Hagiwara, Gallardo, Assavaaree, & Koyani., 2001;Kostopoulou, Miliou, Krontira, & Verriopoulus, 2007;Yin & Zhao, 2008).…”

“…The intrinsic growth rate (r) is a variable that integrates survival, fecundity, development time and reproduction (Malekzadeh-Viayeh et al, 2010), while duplication time (Dt) allows to predict the abundance of rotifers at any point of the growth curve and is similar to the generation time (average time between the birth of parents and the birth of their descendants) (Gillooly, 2000). The maximum population density indicates the abundance that can be supported by the culture conditions as a reflection of the changes in survival and reproduction; it also outlines the acclimation history of the population to the experimental conditions (Krebs, 1985).…”