Biochemical nutrient requirements of the rotifer Brachionus calyciflorus: co‐limitation by sterols and amino acids

Abstract

Summary1. It has been proposed that growth and reproduction of animals is frequently limited by multiple nutrients simultaneously. To improve our understanding of the consequences of multiple nutrient limitations (i.e. co-limitation) for the performance of animals, we conducted standardized population growth experiments using an important aquatic consumer, the rotifer Brachionus calyciflorus. 2. We compared nutrient profiles (sterols, fatty acids and amino acids) of rotifers and their diets to reveal consumer-diet imbalances and thus potentially limiting nutrients. In concomitant growth experiments, we directly supplemented potentially limiting substances (sterols, fatty acids, amino acids) to a nutrient-deficient diet, the cyanobacterium Synechococcus elongatus, and recorded population growth rates. 3. The results from the supplementation experiments corroborated the nutrient limitations predicted by assessing consumer-diet imbalances, but provided more detailed information on co-limiting nutrients. While the fatty acid deficiency of the cyanobacterium appeared to be of minor importance, the addition of both cholesterol and certain amino acids (leucine and isoleucine) improved population growth rates of rotifers, indicating a simultaneous limitation by sterols and amino acids. 4. Our results add to growing evidence that consumers frequently face multiple nutrient limitations and suggest that the concept of co-limitation has to be considered in studies assessing nutrient-limited growth responses of consumers.

Food quantity–quality co‐limitation: Interactive effects of dietary carbon and essential lipid supply on population growth of a freshwater rotifer

“…The rotifers were supplied with a food quantity–quality gradient consisting of five total C concentrations (0.2; 0.4; 0.8; 1.6; 3.2 mg C/L) each consisting of low‐quality S. elongatus supplemented with three different cholesterol concentrations (0; 1; 10 μg/mg C). Cholesterol concentrations in the food suspensions were achieved by adding cholesterol‐containing liposomes, which were prepared as described in Wacker and Martin‐Creuzburg (). Liposome addition increased total mg C/L of the food suspensions by 0.42% per 1 μg cholesterol/mg C. For the statistical analyses, the total mg C/L of the food suspensions was considered.…”

“…where N t ‐1 is the initial number of individuals and N t , H t , and D t are the final numbers of individuals, of newly hatched individuals, and of dead individuals, respectively, during an experimental day (24 hr). The population growth rate of each replicate was calculated by averaging the intrinsic growth rates of consecutive experimental days, which is a well‐established method (Felpeto & Hairston, ; Rothhaupt, ; Wacker & Martin‐Creuzburg, ). In the same manner, fecundity and survival were averaged over experimental days.…”

“…In natural systems, however, herbivores face diverse food sources and take up nutrients as complex packages, which potentially results in multiple nutrient limitations. In a population growth experiment with the freshwater rotifer Brachionus calyciflorus , Wacker and Martin‐Creuzburg () showed a strong positive effect of cholesterol supplementation on population growth rates while feeding on the lipid‐deficient cyanobacterium Synechococcus elongatus at saturating food quantity. In this study, we explored the proposed co‐limitation by food quantity and quality experimentally by considering crossed gradients in food quantity and biochemical food quality.…”

Daphnia's dilemma of adjusting carbon budgets when facing limitations by food quantity and the essential organic compound cholesterol

“…Cholesterol containing liposomes and empty liposomes without further ingredients were prepared according to Wacker and Martin-Creuzburg (Wacker and Martin-Creuzburg, 2012). Cholesterol liposomes were used as food supplements in growth experiments and during the pulse-chase feeding experiment.…”

“…Many recent studies have investigated the performance of herbivores at imbalanced element to C ratios (Sterner and Elser, 2002) or imbalanced ratios of macronutrients (Raubenheimer and Simpson, 2004). Recent studies have focused on herbivore growth limitation by polyunsaturated fatty acids, amino acids, vitamins and sterols (Anderson et al, 2004;Wacker and Martin-Creuzburg, 2012). Sterols are essential food components for herbivorous arthropods (Behmer and Nes, 2003;von Elert et al, 2003), which cannot synthesize cholesterol (the predominant animal sterol) de novo but metabolize it from phytosterols in their diet (Svoboda and Thompson, 1985).…”