Behavioral Fever in Lined Seahorse (Hippocampus erectu) Enhances the Immune Response to Vibrio harveyi Infection

Area of Science:

• Aquaculture
• Fish immunology
• Behavioral ecology

Background:

• Ectotherms exhibit behavioral fever, increasing body temperature to combat infection.
• Vibrio-induced enteritis poses a threat to lined seahorse (Hippocampus erectus) aquaculture.
• Understanding immune responses to infection is crucial for sustainable aquaculture.

Purpose of the Study:

• To investigate if Vibrio harveyi infection induces behavioral fever in lined seahorses.
• To determine the effect of behavioral fever on immune function in infected seahorses.
• To explore the potential of behavioral fever as an eco-friendly aquaculture management strategy.

Main Methods:

• Lined seahorses were infected with Vibrio harveyi and placed in a thermal gradient or constant temperature tank.
• Behavioral fever was assessed by observing seahorse preference for warmer zones.
• Plasma cytokine levels and kidney immune-related gene expression were analyzed.

Main Results:

• Infected seahorses showed a significant preference for warmer temperatures, confirming behavioral fever.
• Behavioral fever led to elevated plasma cytokine levels (PGE2, IL-1β, IL-6, TNF-α).
• Immune gene expression in kidney tissue was modulated by behavioral fever, differing from constant temperature conditions.

Conclusions:

• Behavioral fever in lined seahorses is an adaptive response to Vibrio infection.
• Thermal behavior manipulation can regulate immune responses in seahorses.
• This study provides insights for non-invasive strategies to mitigate enteritis in seahorse aquaculture.