Ocean acidification affects fish spawning but not paternity at CO2 seeps.

Area of Science:

• Marine Biology
• Environmental Science
• Ecology

Background:

• Anthropogenic carbon dioxide (CO2) emissions are increasing ocean acidity.
• Ocean acidification is known to affect fish sensory functions and behavior.
• Reproductive impacts of ocean acidification on wild fish populations remain understudied.

Purpose of the Study:

• To investigate the effects of ocean acidification on the reproductive behavior of wild ocellated wrasse (Symphodus ocellatus).
• To assess how elevated CO2 concentrations influence mating behaviors, spawning success, and paternity in this species.

Main Methods:

• Field study comparing ocellated wrasse populations at sites with ambient and elevated CO2 levels.
• Observation of mating behaviors including dominant male courtship, nest defense, and pair spawning.
• Analysis of paternity rates through assessment of satellite and sneaker male fertilization success.

Main Results:

• Key reproductive behaviors like courtship and nest defense were unaffected by elevated CO2.
• Dominant male ocellated wrasse showed significantly lower rates of pair spawning in elevated CO2 environments.
• A trend of reduced satellite and sneaker male paternity was observed at elevated CO2 levels, despite increased sperm competition risk.

Conclusions:

• Ocean acidification negatively impacts fish reproductive success, specifically reducing pair spawning rates in dominant males.
• While some reproductive behaviors remain resilient, altered spawning success and paternity patterns have implications for wild fish populations.
• Further research is crucial to understand the broader effects of rising CO2 on fish reproduction, food security, and ecosystem stability.