Food quantity and quality shapes reproductive strategies of Daphnia

Abstract

In freshwater environments, one of the challenges aquatic grazers face are periods of suboptimal food quantity and quality. In a life table experiment, the effects of food quantity (a gradient of algae concentration) and quality (a diet of cyanobacteria) on the life histories and resource allocation strategy in Daphnia magna were tested. Growth‐related traits were similarly affected under different food regimes while the reproductive strategies differed in animals exposed to low food quantity and quality. The per‐clutch investment (clutch volume) did not differ between Daphnia fed with cyanobacteria and underfed mothers, but resources were differently allocated; underfed mothers increased their per‐offspring investment by producing fewer, but larger eggs, whereas cyanobacteria‐fed mothers invested in a greater number of eggs of smaller size. I argue that both strategies of resource allocation (number vs. size of eggs) may be adaptive under the given food regime. The results of the study show that the cyanobacteria diet‐driven fitness losses are comparable to losses caused by food quantity, which is only slightly above the growth capability threshold for Daphnia .

Ecological response of Rotaria rotatoria (Bdelloid Rotifera) to unbalanced nitrogen in food: experimental insights from life history strategy and feeding behavior

“…In comparison to rotifers fed with low and middle N-containing algae, those fed with high N diets matured faster and advanced their peak and end reproduction times. This finding is consistent with a previous report, which indicated that animals on an unrestricted diet reproduced earlier than those on a strongly restricted diet of green algae Acutodesmus obliquus (Bednarska 2022). High N-containing algal food (≥A 5 ) shortened the prereproductive and reproductive periods of R. rotatoria compared to low (A 0.5 ) or N-free (A 0 ) algal food, but the post-reproductive period was lengthened first and then shortened with increased N concentration in the medium.…”

Experimental Studies on Zooplankton-Toxic Cyanobacteria Interactions: A Review

“…Daphniids are often considered the most suitable zooplankton to control cyanobacterial blooms. The large body size and adequate growth rates of Daphnia magna on cyanobacterial diets [ 19 ] indicate that the species is ideally suited for lake management. This is probably the reason for the emphasis on studies on Daphnia ; nineteen species of the genus Daphnia have been used in experiments to test the effects of cyanobacteria or cyanotoxins on their fitness, while thirteen species of all the other cladocerans have been used in similar studies ( Table 2 ).…”