Aquatic insects differentially affect lake sturgeon larval phenotypes and egg surface microbial communities

Area of Science:

• Ecology
• Ichthyology
• Microbial Ecology

Background:

• Limited understanding of how microbial communities and aquatic insects influence stream fish early life stages.
• Spatial overlap exists between vulnerable early life stages of stream fishes (e.g., lake sturgeon) and aquatic insects/microbes on spawning substrates.
• Species interactions across trophic levels are likely common but poorly understood, affecting fish populations.

Purpose of the Study:

• To investigate the effects of different aquatic insect feeding strategies (FS) on lake sturgeon (Acipenser fulvescens) egg and embryo development.
• To quantify impacts on egg surface microbial communities, hatching success, and early life-history traits.
• To determine how insect-fish interactions influence variability in lake sturgeon recruitment.

Main Methods:

• Experimental incubation of lake sturgeon eggs with four different aquatic insect FS taxa (predators, scrapers, collector-filterers, control).
• Quantification of egg surface bacterial and lower eukaryotic community composition and abundance.
• Measurement of egg size, incubation time, free embryo size (total length), yolk-sac area, and survival to hatch.

Main Results:

• Significant variation in mean egg size, incubation period, and free embryo size (yolk sac, total length) among insect treatments.
• Eggs exposed to predators exhibited lower survival rates and shorter incubation periods.
• Egg surface microbial community composition and bacterial abundance varied significantly across insect treatments and time.

Conclusions:

• Interactions with aquatic insects, particularly predators, have significant lethal and non-lethal effects on lake sturgeon early life stages.
• These interactions contribute to trait variability in lake sturgeon, potentially impacting population-level recruitment.
• Understanding these cross-trophic interactions is crucial for conservation efforts of stream fishes.