Dietary effects on life history traits of riverine Bosmina

Abstract

1. We compared growth, reproduction and life history characteristics of Bosmina raised on Ohio River seston versus a unialgal culture (Scenedesmus acutus), to assess potential nutritional constraints experienced by riverine populations. 2. Bosmina grew well in both treatments during their juvenile stage. Analysis of variance showed that Bosmina growth prior to the start of reproduction did not differ significantly between the treatments. After the onset of reproduction Bosmina fed on Scenedesmus grew faster and exhibited higher fecundity than their counterparts fed river seston. 3. Significant quantities of triacylglycerol (visible lipid droplets) were gradually accumulated in Bosmina fed on Scenedesmus. Visual lipid ovary indices were positively correlated with adult growth rate and fecundity and negatively correlated with longevity. 4. Biochemical analysis showed that Scenedesmus had significantly greater total x3, x6 and polyunsaturated fatty acids (PUFA) whereas river seston had more eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Thus, in contrast to Daphnia, EPA and DHA do not appear to influence Bosmina growth or reproductive performance, but linolenic acid or total PUFA may be important. 5. Comparatively weak performance by Bosmina feeding on river seston suggest that nutritional constraints may be important despite high particulate organic carbon and low C : N and C : P of river seston.

Growth and development time of subtropical Cladocera Diaphanosoma birgei Korinek, 1981 fed with different microalgal diets

“…The longer duration of D. birgei in Hp diet revealed that animals which produced more offspring and grew faster during their peak reproduction period died earlier (Ag-25+Hp-75 diet), whereas animals that grew slowly and had a lower reproduction output survived longer (Hp diet). Acharya et al (2005) reported similar findings. Bosmina, which reproduced more and earlier, had a lower survival rate than those reproducing later and slower.…”

“…Life history traits of cladocerans are known to change according to resource quality or quantity (Acharya et al, 2005) and this view is further supported by this experiment. The longer duration of D. birgei in Hp diet revealed that animals which produced more offspring and grew faster during their peak reproduction period died earlier (Ag-25+Hp-75 diet), whereas animals that grew slowly and had a lower reproduction output survived longer (Hp diet).…”

Consumer growth linked to diet and RNA—P stoichiometry: Response of Bosmina to variation in riverine food resources

“…Because water regulation structures are common worldwide (Nilsson et al 2005), our findings may be generally applicable in rivers where seasonal flood-pulse cycles have been replaced by irregular hydrographs (Sparks et al 1998). Although differences in growth rates between high and low discharge conditions (ambient seston concentrations) were relatively small (m 5 0.40 vs. 0.55 d 21 , respectively), our related study showed that small differences in juvenile growth rates were later followed by differences in adult body size, age at maturation, brood size and frequency, and size of neonates (Acharya et al 2005). The cumulative impact arising from the various life history responses (twofold difference in total fecundity) may be of sufficient magnitude to account in part for the sixfold range of variation in population size between low-and high-flow periods (Fig.…”

“…In a related study, we compared life history traits of Bosmina raised on seston (collected during low discharge; C : P 5 115) with those fed P-sufficient green algae (Acharya et al 2005). Although the P content of both diets was similar, Bosmina raised on green algae grew larger, produced more offspring, and exhibited larger lipid reserves than those fed river seston.…”

“…For growth rate estimation, initial and final body area measurements were converted to body dry mass by a previously derived dry weight-body area regression (p , 0.0001, R 2 . 0.90; Acharya et al 2005). Growth rate, m (d 21 ), was calculated as m~ln(final weight=initial weight)=days Two replicates of six animals each were placed in 25-mL glass tubes (for P analysis), and five or six replicates of one animal each were placed in nuclease-free Eppendorf tubes (for RNA analysis) with ultrafine tweezers (Dumont) and immediately frozen at 280uC for later analysis.…”