Bottom water hypoxia suppresses fish chorusing in estuariesa)

Area of Science:

• Marine biology
• Ecology
• Environmental science

Background:

• Coastal hypoxia is an increasing threat due to nutrient pollution.
• Hypoxia negatively impacts fish populations, including their habitats, size, and growth.
• Understanding hypoxia's effects on fish reproductive behavior is crucial for conservation.

Purpose of the Study:

• To investigate the impact of hypoxia on fish chorusing and reproductive behavior in estuaries.
• To assess the relationship between dissolved oxygen levels and fish acoustic signals.

Main Methods:

• Utilized integrated water quality meters and passive acoustic recorders to monitor dissolved oxygen and fish chorusing simultaneously.
• Deployed passive acoustic recorders near established water quality monitoring stations in hypoxic estuaries.
• Analyzed acoustic data for changes in fish chorusing during hypoxic events (dissolved oxygen < 4.0 mg/L).

Main Results:

• Fish chorusing diminished or ceased entirely when hypoxic conditions occurred.
• A significant correlation was found between low dissolved oxygen and reduced acoustic power in the 100-200 Hz band, linked to red drum calls.
• The study identified specific acoustic signatures associated with hypoxia's impact on fish behavior.

Conclusions:

• Passive acoustic monitoring is effective for studying hypoxia's effects on fish behavior in estuaries.
• Integrated monitoring systems can provide continuous data on water quality and fish chorusing.
• Findings highlight the need for estuarine hypoxia monitoring to protect critical fish spawning habitats.