Pathways linking nutrient enrichment, habitat structure, and parasitism to host-resource interactions.

Autor: Penczykowski RM; School of Biology, Georgia Institute of Technology, Atlanta, GA, 30332, USA. rpenczykowski@wustl.edu.; Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130, USA. rpenczykowski@wustl.edu., Fearon ML; Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA., Hite JL; Department of Biology, Indiana University, Bloomington, IN, 47405, USA.; Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI, 53706, USA., Shocket MS; Department of Biology, Indiana University, Bloomington, IN, 47405, USA.; Department of Geography, University of Florida, Gainesville, FL, 32611, USA., Hall SR; Department of Biology, Indiana University, Bloomington, IN, 47405, USA., Duffy MA; School of Biology, Georgia Institute of Technology, Atlanta, GA, 30332, USA.; Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
Jazyk: angličtina
Zdroj: Oecologia [Oecologia] 2024 Feb; Vol. 204 (2), pp. 439-449. Date of Electronic Publication: 2023 Nov 11.
DOI: 10.1007/s00442-023-05469-9
Abstrakt: Human activities simultaneously alter nutrient levels, habitat structure, and levels of parasitism. These activities likely have individual and joint impacts on food webs. Furthermore, there is particular concern that nutrient additions and changes to habitat structure might exacerbate the size of epidemics and impacts on host density. We used a well-studied zooplankton-fungus host-parasite system and experimental whole water column enclosures to factorially manipulate nutrient levels, habitat structure (specifically: mixing), and presence of parasites. Nutrient addition increased infection prevalence, density of infected hosts, and total host density. We hypothesized that nutrients, mixing, and parasitism were linked in multiple ways, including via their combined effects on phytoplankton (resource) abundance, and we used structural equation modeling to disentangle these pathways. In the absence of the parasite, both nutrients and mixing increased abundance of phytoplankton, whereas host density was negatively related to phytoplankton abundance, suggesting a mixture of bottom-up and top-down control of phytoplankton. In the presence of the parasite, nutrients still increased phytoplankton abundance but mixing no longer did, and there was no longer a significant relationship between host density and phytoplankton. This decoupling of host-resource dynamics may have resulted from reduced grazing due to illness-mediated changes in feeding behavior. Overall, our results show that the impact of one human activity (e.g., altered habitat structure) might depend on other human impacts (e.g., parasite introduction). Fortunately, carefully designed experiments and analyses can help tease apart these multifaceted relationships, allowing us to understand how human activities alter food webs, including interactions between hosts and their parasites and resources.
(© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)
Databáze: MEDLINE
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