Dietary Essential Amino Acids Affect the Reproduction of the Keystone Herbivore Daphnia pulex

Abstract

Recent studies have indicated that nitrogen availability can be an important determinant of primary production in freshwater lakes and that herbivore growth can be limited by low dietary nitrogen availability. Furthermore, a lack of specific essential nitrogenous biochemicals (such as essential amino acids) might be another important constraint on the fitness of consumers. This might be of particular importance for cladoceran zooplankton, which can switch between two alternative reproductive strategies – the production of subitaneously developing and resting eggs. Here, we hypothesize that both the somatic growth and the type of reproduction of the aquatic keystone herbivore Daphnia is limited by the availability of specific essential amino acids in the diet. In laboratory experiments, we investigated this hypothesis by feeding a high quality phytoplankton organism (Cryptomonas) and a green alga of moderate nutritional quality (Chlamydomonas) to a clone of Daphnia pulex with and without the addition of essential amino acids. The somatic growth of D. pulex differed between the algae of different nutritional quality, but not dependent on the addition of dissolved amino acids. However, in reproduction experiments, where moderate crowding conditions at saturating food quantities were applied, addition of the essential amino acids arginine and histidine (but not lysine and threonine) increased the total number and the developmental stage of subitaneous eggs. While D. pulex did not produce resting eggs on Cryptomonas, relatively high numbers of resting eggs were released on Chlamydomonas. When arginine and histidine were added to the green algal diet, the production of resting eggs was effectively suppressed. This demonstrates the high, but previously overlooked importance of single essential amino acids for the reproductive strategy of the aquatic keystone herbivore Daphnia.

The Importance of Phytoplankton Biomolecule Availability for Secondary Production

“…It has, however, been previously reported that EAA and protein deficiencies trigger the induction of sexual reproduction in cladoceran zooplankton, leading to stronger effect on offspring production and population size than on somatic growth (Koch et al, 2009(Koch et al, , 2012Fink et al, 2011;Bouchnak and Steinberg, 2014). In our study, the protein content, as well as the amount of NEAA, boosted the somatic growth of Daphnia when sterols were adequate (see GLM results on Table 3), but direct connections between proteins, EAAs or NEAAs and reproduction could not be detected.…”

“…Phytoplankton is in general rich in AAs, but the AA profiles can differ significantly between even closely related species (Brown et al, 1997;Koch et al, 2012). For zooplankton, the essential AAs are considered to be the same as for insects and humans (Supplemental Table 2; Fink et al, 2011). In cladoceran zooplankton, the availability of dietary proteins and essential amino acids (EAAs) has been connected to resting egg production rather than to somatic growth.…”

“…In cladoceran zooplankton, the availability of dietary proteins and essential amino acids (EAAs) has been connected to resting egg production rather than to somatic growth. More precisely, high dietary arginine and histidine have been found to induce the production of subitaneous offspring, whereas the lack of these EAAs has led to sexual resting egg production (Koch et al, 2009(Koch et al, , 2012Fink et al, 2011;Bouchnak and Steinberg, 2014). Therefore, proteins and AAs can be considered as resources affecting the reproductive mode, performance, and population growth of zooplankton in nature.…”

A Molecular and Cellular Context-Dependent Role for Ir76b in Detection of Amino Acid Taste

“…Females, in particular, require large supplies of amino acids for synthesizing egg yolk (Dimond et al, 1956). Restriction of amino acids thus has a direct impact on female fecundity (Chang, 2004; Dimond et al, 1956; Fink et al, 2011). Amino acid deprivation also significantly affects larval growth and development, as well as adult life span (Baltzer et al, 2009; Britton and Edgar, 1998; Chang, 2004; Grandison et al, 2009; Vrzal et al, 2010).…”

Correlation between body size and fatty acid and essential amino acid composition of round goby (Neogobius melanostomus) and monkey goby (Neogobius fluviatilis) from the Rhine River (Germany)

“…• C for 24 h. Samples were neutralized with 200 µl of an alkaline solution (5 M KOH, 1 M triethanolamine) and centrifuged at 11,000 × g for 10 min to remove precipitated perchlorate (Fink et al 2011). Subsequently, 20 µl of the supernatant were transferred into a HPLC vial and diluted with 180 µl ultrapure water.…”