Interaction of changes in food quality and temperature reveals maternal effects on fitness parameters of a keystone aquatic herbivore

Abstract

We investigated the interaction of intergenerational temperature and food quality change on the fitness of two species of Daphnia, a freshwater keystone herbivore. The effect of a change in temperature (15uC vs. 20uC) and food quality (Cryptomonas sp. as high-quality food vs. Chlamydomonas sp. as relatively low-quality food) on juvenile growth rate and clutch size of Daphnia magna and Daphnia pulex was measured in 16 combinations of maternal and offspring environments in standardized growth assays. Both species showed similar responses. The positive effect of food quality on growth rate and clutch size was stronger if the maternal diet was of low quality. High maternal diet quality generally increased growth rate and reproduction, especially if the offspring diet was of low quality. The maximum fitness was attained by animals acclimated at 15uC and growing at 20uC, combining the faster growth rate at warm assay temperature and bigger clutch size of cold-acclimated animals. Intergenerational temperature regime had a strong influence on the effects of maternal and offspring food quality. Good maternal food quality was more important for fitness under less favorable temperature conditions. Low offspring food quality was more detrimental to fitness in animals experiencing temperature change between maternal acclimation and growth assay and less so under constant temperature conditions. Intergenerational changes in temperature and the maternal effects of food quality strongly affect the dietary requirements of these organisms. Hence, extrapolation from studies conducted under constant temperature conditions may seriously underestimate dietary constraints in natural environments.

Long‐term effects of fungicides on leaf‐associated microorganisms and shredder populations—an artificial stream study

“…However, despite a higher content of single fatty acids, overall fatty acid content and the content of all major fatty acid types (saturated, monounsaturated, and polyunsaturated) were by trend reduced (by 10-25%; Supplemental Data, Table S3) in the fungicide treatment. This observation further supports the anticipated lower food quality of fungicide-exposed leaf material relative to control leaf material because diet quality for crustaceans is known to be highly dependent on the resources' fatty acid composition [45,46]. Furthermore, the applied fungicides also tend to adsorb to leaf material [8,12], suggesting their uptake via food.…”

Equal relevance of omega‐3 and omega‐6 polyunsaturated fatty acids for the fitness of Daphnia spp.

“…The saturation threshold approach used in our study to access possible interspecific differences between D. pulex and D. magna did not reveal significant results. We assume that the effect sizes depending on EPA-and ARA-supplementation were too similar to reveal any differences and therefore we suggest the experiments to be repeated at colder temperatures, where possible interspecific differences may be more visible due to a higher requirement for highly unsaturated fatty acids to maintain proper membrane fluidity (Hazel 1995;Valentine and Valentine 2004;Masclaux et al 2012;Pajk et al 2012). Nevertheless, we do provide evidence for interspecific differences in the response of the two Daphnia species that might be explained exclusively by insufficient amounts of EPA and/or ARA: the growth rate and the clutch size of D. magna along the EPA and ARA concentration clearly followed a saturation curve (between 30% and 50% of the variance was explained by the modified Monod model), while this was not the case for D. pulex.…”

Temperature reaction norms ofDaphnia carinatafitness: the effects of food concentration, population density, and photoperiod

“…However, there are few studies considering three or more variables simultaneously in the literature. One exception is Pajk et al (2012) who demonstrated that Daphnia fitness was affected not only by assay food quality and assay temperature, but also by maternal food quality and maternal temperature. These results suggest that simultaneously investigating multiple variables would provide more insights into understanding zooplankton responses to environmental changes.…”

“…In addition to food quantity, interactions between temperature and food quality have recently come into focus. For example, the growth of D. magna did not respond to dietary phosphorus limitation when the temperature was the lowest, but was more depressed with increasing temperature (Persson et al 2011). Pajk et al (2012 reported that the interactions between temperature and food quality on the fitness parameters of D. magna and Daphnia pulex were influenced by maternal conditions.…”

“…Distribution, abundance, production, and evolution of zooplankton are regulated by many ecological variables, of which temperature is the most studied and likely the most important (Burns 1969;Giebelhausen and Lampert 2001;Pajk et al 2012). Increasing temperature usually enhances zooplankton feeding, growth, and reproduction (Burns 1969;Korpelainen 1986;Achenbach and Lampert 1997;Kee and Ebert 1996).…”