Free-living parasite infectious stages promote zooplankton abundance under the risk of predation
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Free-living parasite infectious stages, such as the cercariae of trematodes (flatworms), can represent substantial biomass in aquatic ecosystems, yet their interactions with other planktonic fauna are poorly understood. Given that cercariae are consumed by various aquatic predators, sometimes even preferentially over zooplankton, their presence may decrease predation pressure on free-living organisms within similar trophic niches by serving as alternate prey. Here, we experimentally examined how the presence of cercariae (Plagiorchis sp.) affected the population dynamics of common freshwater zooplankton (Daphnia sp.) in the presence of a predator (the larval dragonfly, Leucorrhinia intacta) known to consume both. After seeding 48 mesocosms with starting populations of Daphnia, we used four treatments (12 replicates each) representing a factorial combination of the absence/presence of both cercariae and dragonfly larvae and tracked Daphnia populations over 4 weeks. We found a significant interaction between the presence of cercariae and predators on Daphnia population size. When faced with predation pressure, Daphnia reached ~ 50% higher numbers when accompanied by cercariae than without, suggesting a “protective” effect of the latter by acting as substitute prey. Within aquatic ecosystems, an abundance of trematodes may prove advantageous for zooplankton communities that share common predators, but further studies will be needed to determine how this varies depending on the predator, trematode, and zooplankton taxa involved.
KeywordsParasite Prey Zooplankton Predation Food web
We thank L. Santos and J. Nguyen for experimental assistance, as well as S. J. McCauley for advice. This work was supported by an NSERC Discovery grant to J. K. (RGPIN-2015-05566).
Author contribution statement
BS and JK conceived and designed the experiments. BS performed the experiments. BS and JK analyzed the data and wrote the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Blankespoor H (1970) Host-parasite relationships of an avian trematode, Plagiorchis noblei Park, 1936. PhD Dissertation. Iowa State University Library. http://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=5816&context=rtd. Accessed 5 May 2019
- Blankespoor HD (1977) Notes on the biology of Plagiorchis noblei Park, 1936 (Trematoda: Plagiorchiidae). Proc Helminthol Soc Wash 44:44–50Google Scholar
- Ebert D (2005) Ecology, epidemiology, and evolution of parasitism in Daphnia. National Center for Biotechnology Information, Bethesda, Md. http://www.ncbi.nlm.nih.gov/books/NBK2042/
- Faltýnková A (2005) Larval trematodes (Digenea) in molluscs from small water bodies near Šeské Budšjovice, Czech Republic. Acta Parasitol 50:49–55Google Scholar
- Gliwicz ZM, Pijanowska J (1989) The role of predation in zooplankton succession. In: Plankton ecology. Springer, Berlin, pp 253–296Google Scholar
- Johnston TH, Angel LM (1951) The life history of Plagiorchis jaenschi, a new trematode from the Australian water rat. Trans R Soc S Aust 74:49–58Google Scholar
- Kuris AM, Hechinger RF, Shaw JC, Whitney KL, Aguirre-Macedo L, Boch CA, Dobson AP, Dunham EJ, Fredensborg BL, Huspeni TC, Lorda J, Mababa L, Mancini FT, Mora AB, Pickering M, Talhouk NL, Torchin ME, Lafferty KD (2008) Ecosystem energetic implications of parasite and free-living biomass in three estuaries. Nature 454:515–518CrossRefGoogle Scholar
- Lafferty KD, Allesina S, Arim M, Briggs CJ, De Leo G, Dobson P, Dunne JA, Johnson PTJ, Kuris AM, Marcogliese DJ, Martinez ND, Memmott J, Marquet PA, McLaughlin JP, Mordecai EA, Pascual M, Poulin R, Thieltges DW (2008) Parasites in food webs: the ultimate missing links. Ecol Lett 11:533–546CrossRefGoogle Scholar
- Schell SC (1985) Handbook of trematodes of North America north of Mexico. University of Idaho Press, MoscowGoogle Scholar
- Thieltges DW, Amundsen PA, Hechinger RF, Johnson PT, Lafferty KD, Mouritsen KN, Preston DL, Reise K, Zander CD, Poulin R (2013) Parasites as prey in aquatic food webs: implications for predator infection and parasite transmission. Oikos 122:1473–1482Google Scholar
- Watertor JL (1965) Intraspecific variation among trematodes of the genus Telorchis. Ph.D. Dissertation. Iowa State University Library. https://doi.org/10.31274/rtd-180813-416