Journal of Freshwater Ecology

Parasites in Freshwater Ecosystems: Altered Flows of Energy on Organisms’ Growth, Reproduction, and Community Structure

Parasites are known to affect organisms in subtle ways (e.g., altered growth and reproductive success, ability to find and attract suitable mates, and structure and stability of ecosystems), as well as near-term death. Finding and describing these relationships typically requires both extensive field work and laboratory analysis. Many species and genera of parasites, broadly defined, remain to be described both taxonomically and ecologically. Parasite species are often limited to one host, while others can be generalists utilizing a range of hosts within some taxon. Some parasite species have complex life cycles requiring one or more intermediate hosts, while others have a direct life history without intermediate hosts. The study of these questions is facilitated with the use of genomics but represents a huge amount of research to be done. Ongoing climate change adds urgency to the understanding of existing biodiversity as ecosystems change, shift or even disappear.

Recent work has shown the vertebrate hosts have allelic variability in major histocompatibility complex (MHC) loci that affect host susceptibility to parasites, apparently as a Red Queen evolutionary relationship with potential parasites. Such examples of co-evolution or co-speciation are likely common. The ability of endoparasites to utilize host resources for the benefit of parasite reproduction also appears to be common, with many variations on the theme.

Parasites in any ecosystem can be important as regulators of host populations by altering or halting reproduction, slowing growth, or diverting host resources leading to impaired function or death. Seasonality is often important to parasite life history, such that altered temperature or precipitation can be a brake or an accelerant on both parasite numbers and parasite ability to infect hosts. Global climate change may affect both parasite population size and host susceptibility in unpredictable ways. Parasites themselves are a key but often poorly known part of biodiversity along with their role shaping biodiversity on both local and global levels. Freshwater ecosystems and species are imperiled by anthropogenic changes. Do these changes make hosts more vulnerable to both current parasites as well as new parasites adapted to a host? Human health and agriculture are also threatened by parasite adaptation to changing freshwater ecosystems.

This Article Collection has a wide scope of interest. The influence of parasite infestations on all taxa associated with global freshwater ecosystems is of interest. Topics of interest include, but are not limited to:

• Influence of parasite infection on host population size and stability
• Factors affecting parasite reproduction
• Invasive species ecology of both hosts and parasites
• Genetic basis of host resistance and how this might vary in closely related hosts
• Analysis of morphological features enabling parasite function
• Chemical signaling that may attract or repel parasites

Keywords:

1. biodiversity
2. host specificity
3. life history
4. morphology
5. taxonomy

­­All manuscripts submitted to this Article Collection will undergo a full peer-review; the Guest Advisor for this Collection will not be handling the manuscripts (unless they are an Editorial Board member).

Please review the journal scope and author submission instructions prior to submitting a manuscript.

The deadline for submitting manuscripts is March 6, 2026.

Please contact Kara Roberts at kara.roberts@taylorandfrancis.com with any queries on discount codes regarding this Article Collection.

Bruce Stallsmith is an emeritus freshwater fish ecologist at the University of Alabama in Huntsville. His current research interests include sex ratios in the percid fish genera Etheostoma and Percina in spawning season, and the apparent co-speciation of Etheostoma hosts and Aethycteron monogenean gill parasites. More broadly his interests are freshwater fishes of the southern Appalachian mountains and also Panamá.

Kara Million is an Assistant Professor at University of North Alabama. Her research interests include reproductive behaviors in darters (family Percidae) and the host-parasite relationships between darters and their specialist gill parasites (genus Aethycteron). Her current research projects include the study of male-male territorial interactions in darters, and the cophylogenetic relationships between darters and Aethycteron parasites.

The Guest Advisors declare no conflict of interest.