Fish predation on Notonecta (Hemiptera): relationship between prey risk and habitat utilization.

Area of Science:

• Ecology
• Aquatic Ecology
• Predator-Prey Dynamics

Background:

• Insectivorous fishes are significant predators in aquatic ecosystems.
• Understanding predator-prey interactions is crucial for aquatic community structure.
• Notonecta species (water boatmen) are common prey items for various fish.

Purpose of the Study:

• To assess the prey risk of six Notonecta species when exposed to insectivorous fishes.
• To determine the potential for coexistence between Notonecta species and their fish predators.
• To evaluate the influence of environmental factors, such as vegetation, on prey risk.

Main Methods:

• Laboratory experiments were conducted to simulate predator-prey interactions.
• Six Notonecta species were exposed to two species of insectivorous fishes (Lepomis cyanellus and L. gibbosus).
• Prey risk was assessed based on species' traits and their ability to avoid predation, with and without vegetation cover.

Main Results:

• Notonecta lunata and N. petrunkevitchi exhibited the lowest prey risk due to smaller size, lighter coloration, and better evasion tactics.
• Larger, melanistic species (N. irrorata, N. insulata) were more vulnerable to fish predation.
• Vegetation presence reduced overall prey risk but did not change the relative risk among Notonecta species.
• Laboratory-assessed prey risk correlated with field observations of Notonecta distribution relative to fish.

Conclusions:

• Fish predation is a key factor shaping the habitat utilization patterns of Notonecta species.
• Species-specific traits significantly influence survival rates in the presence of predators.
• The findings highlight the ecological importance of predation in structuring aquatic invertebrate communities.