Host-Parasite Interactions in Aquatic Systems

Interactions between aquatic hosts and their parasites encompass a vast array of biological relationships, from microscopic protozoans and viruses to multicellular helminths and crustacean ectoparasites. These associations drive evolutionary arms races in which hosts deploy innate and adaptive defences—such as barrier fortification, inflammatory cascades and antibody production—while parasites evolve evasion strategies including immunomodulation, antigenic variation and tissue tropism. The outcome of infection shapes individual fitness, population dynamics and ecosystem health, with profound implications for wild fisheries, aquaculture sustainability and zoonotic risk. Recent advances in genomics, transcriptomics and microbial ecology have illuminated key mechanisms by which parasites manipulate host signalling and tissue repair, and how co-infections or environmental stressors can exacerbate disease severity. A holistic view of host-parasite ecology in freshwater and marine environments is now essential for the development of precise management practices, vaccine design and novel therapeutics that safeguard both biodiversity and food security.

Research from Nature Portfolio

Recent studies have characterised co-infections in marine aquaculture by caligid copepods and opportunistic bacterial pathogens. One investigation combined molecular identification, histopathology and immune profiling to dissect an outbreak in farmed seabass and mullet, revealing severe gill and liver damage driven by sequential copepod infestation and Vibrio alginolyticus proliferation. The work demonstrated that integrated treatment—prolonged oxidative baths, a nature-identical antiparasitic compound and probiotic supplementation—effectively cleared both parasite and bacterial burdens, underscoring the value of multifaceted control strategies that address primary and secondary infections in intensive culture systems.

Host-Parasite Interactions in Aquatic Systems publication trend

The graph below shows the total number of articles in host-parasite interactions in aquatic systems across all publications each year (not limited to Nature Index journals).

Technical terms

Ectoparasite: A parasite that lives on the surface of its host, such as sea lice on fish skin and gills.

Endoparasite: A parasite that inhabits the internal tissues or organs of its host, including helminths in the gastrointestinal tract.

Immunomodulation: The alteration of host immune responses by a parasite to enhance its survival, through suppression or redirection of host defences.

Epithelial hyperplasia: The rapid proliferation of skin or mucosal cells, often as a host defence mechanism that can physically expel or isolate parasites.

References

1. Investigating dynamics, etiology, pathology, and therapeutic interventions of Caligus clemensi and Vibrio alginolyticus co-infection in farmed marine fish. Scientific Reports (2024).
2. Divergent RNA viruses infecting sea lice, major ectoparasites of fish. PLOS Pathogens (2023).
3. Keratinocytes drive the epithelial hyperplasia key to sea lice resistance in coho salmon. BMC Biology (2024).
4. Deciphering the impact of endoparasitic infection on immune response and gut microbial composition of Channa punctata. Frontiers in Cellular and Infection Microbiology (2024).