Disease and pollution alter Daphnia taxonomic and clonal structure in experimental assemblages

Abstract

Summary 1. Environmental stressors can influence population and community structure. However, the majority of experimental work on multiple environmental stressors has been done at the individual level only. 2. In this work, we followed changes in experimental assemblages of Daphnia (waterfleas; consisting of two taxa and three clones per taxon) after exposure to the fungal parasite Metschnikowia sp. and/or the pesticide diazinon. 3. We found a significant shift in taxonomic and clonal composition under both stressors. Strikingly, in the parasite and parasite + pesticide treatments, one taxon went extinct. While the pesticide had no effect on total parasite prevalence, the taxon that was more susceptible to extinction was, at the same time, more infected when additionally exposed to the pesticide. Furthermore, the density of all adult females was significantly reduced in the parasite treatment, but not in the pesticide treatment. 4. Our results demonstrate that the dynamics of Daphnia assemblages are altered by parasites and pesticide exposure. Given the key role of Daphnia in aquatic food webs in transferring primary production into fish food, this could be of wide significance in aquatic ecosystems.

Comparative Pharmacology and Toxicology of Pharmaceuticals in the Environment: Diphenhydramine Protection of Diazinon Toxicity in Danio rerio but Not Daphnia magna

“…We specifically hypothesized that DPH would confer a protective effect for DZN poisoning in aquatic invertebrates and vertebrates. Threshold toxicity values observed here for Daphnia magna to DZN generally followed previous reports for both acute (40)(41)(42) and subchronic (42,43) endpoints. Though DPH and other antihistamine toxicity data for invertebrates is not as readily available as DZN (44), Daphnia magna observations from the present study are similar to previous reports by our group (26) and others (45).…”

Interplay between fungicides and parasites: Tebuconazole, but not copper, suppresses infection in a Daphnia-Metschnikowia experimental model

“…Interaction between these stressors can exacerbate or mitigate their otherwise independent effects [ 29 ]. This study was motivated by the need for a clarification on how pesticide pollution affects the eventual spread of diseases [ 23 , 42 ]. Our major finding was that two common agrochemicals (fungicides) cause different outcomes in a host-parasite ( Daphnia - M .…”

“…galeata ; hereafter designated as clone 12 and clone 47, respectively) were selected as model hosts, and maintained as single-cohort group cultures in the laboratory. These Daphnia genotypes were isolated from Lake Ammersee (Germany), and they are part of a collection of Daphnia clones that have been used in other studies [ 23 , 34 ]. The use of more than one genotype/taxon increases ecological relevance, but the use of numerous clones is often not logistically feasible.…”

“…Furthermore, parasites are important drivers of genetic diversity in host populations, as demonstrated in experimental and field studies [ 20 , 21 ]. Host-parasite relationships are strongly dependent on environmental context [ 22 ], and their outcome can be altered by the presence of natural and anthropogenic stressors, including pesticides [ 2 , 23 ]. Interactive scenarios between parasites and pesticide exposure have been shown to be mostly synergistic, causing exacerbated impacts on the host´s sensitivity to the pollutant [ 5 , 24 ] or on their susceptibility to infection [ 25 , 26 ].…”

Offspring performance of Daphnia magna after short-term maternal exposure to mixtures of microcystin and ammonia

“…Offspring from a highest level of mixed pollutants showed a higher mortality rate than other groups but produced as many neonates per clutch as the control, which suggested that energy allocated to maintain production was not reduced although the shortened lifespan meant cost of fitness (Buser et al 2012). Offspring from other lower levels of mixed or single pollutants showed no significant difference in survival or development, and no mortality was observed before maturation in our experiments, indicating that the offspring was not severely affected.…”