Parasitic Interactions in Freshwater Fish Populations
Summary
Freshwater fish inhabit a mosaic of ecological niches where they encounter a myriad of parasitic organisms, ranging from ectoparasitic crustaceans and monogeneans to endoparasitic nematodes and cestodes. These interactions are shaped by environmental variables such as water temperature, host density and anthropogenic disturbance. Parasites can alter host physiology and behaviour, impairing growth, reproduction and survival, with cascading effects on population dynamics and community structure. Immunological defences in teleosts—including mucosal barriers, innate cellular responses and adaptive humoral immunity—mediate resistance and tolerance, yet co-evolution often favours parasite evasion strategies. Recent advances in high-throughput sequencing and in vivo imaging have elucidated the molecular dialogues between host and parasite, revealing genetic determinants of virulence and host susceptibility. At the ecosystem level, parasitic infections serve as indicators of water quality and biodiversity health, while in aquaculture they represent a major challenge requiring integrated management. A holistic understanding of parasitic interactions demands interdisciplinary approaches that bridge ecology, immunology, genomics and fisheries science to inform conservation and sustainable production practices.
Research from Nature Portfolio
Recent studies have applied genome-wide association analyses to identify immunogenetic loci linked to resistance against monogenean trematodes in carp, uncovering signatures of rapid host adaptation. Novel environmental DNA (eDNA) techniques have been validated for non-invasive surveillance of parasitic helminths in riverine systems, enabling early detection of invasion events. In addition, investigations using single-cell transcriptomics have characterised the mucosal immune landscape of salmonids during copepod infestation, revealing key cytokine networks that underpin effective epithelial defence.
Parasitic Interactions in Freshwater Fish Populations publication trend
The graph below shows the total number of articles in parasitic interactions in freshwater fish populations across all publications each year (not limited to Nature Index journals).
Technical terms
Ectoparasite: A parasite that lives on the external surface of its host.
Parasite burden: The number or biomass of parasites infecting a single host organism.
Host specificity: The range of host species that a parasite can infect.
Co-infection: Simultaneous infection of a single host by multiple parasite species.
Environmental DNA (eDNA): Genetic material obtained directly from environmental samples for species detection.
References
- Seasonal variation of parasitism in pejerrey Odontesthes bonariensis (Atheriniformes, Atherinopsidae) from La Viña reservoir (Córdoba, Argentina). Revista Brasileira de Parasitologia Veterinária (2008).
- Molecular and morphological identification of Lernaea spp. in Cyprinid fishes from two districts in Yogyakarta, Indonesia. Veterinary World (2023).
- Prevalence of Lernaea cyprinacea Infections in Indian Major Carp at Fish Farms of Bihar, India. UTTAR PRADESH JOURNAL OF ZOOLOGY (2024).
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