How reef fish may use the moon's cycle to manipulate the sex of their offspring
A recent study published in Proceedings of the Royal Society B: Biological Sciences has uncovered that the phase of the moon influences the sex of offspring in the sixbar wrasse, a fish found in Pacific coral reefs. Led by Professor Jeff Shima from Te Herenga Waka—Victoria University of Wellington, the research reveals that offspring born near a new moon are more likely to develop as males, while those born closer to a full moon are more likely to become females. This pattern is significant because, although sixbars spawn most frequently during the new moon, these offspring generally have lower survival rates. The study suggests that sixbar wrasse born during the new moon adjust their development to increase their chances of survival, leading to a higher likelihood of male development.
The study on sixbar wrasse reveals that spawning during a new moon, though risky due to lower survival rates for offspring, might be a strategic choice. The few offspring that survive this period are more likely to become males, who can produce more offspring in the sixbar mating system, thus providing a significant reproductive advantage. This high-risk, high-reward strategy might be balanced with lower-risk spawning during full moons. The findings suggest that some species could have evolved to use lunar cycles to influence offspring sex and growth rates, potentially optimizing their reproductive success.
Sixbar wrasse larvae can adjust their development to time their arrival at coral reefs under optimal conditions, often coinciding with the new moon's darkness. This adaptation might help them avoid predators and take advantage of specific environmental conditions. The study highlights the broader implications for understanding lunar reproductive cycles in marine species, which may be influenced by factors like tides, food availability, and predator avoidance. However, human-induced environmental changes, such as artificial light and altered cloud cover due to climate change, could disrupt these natural patterns, affecting marine life’s growth, survival, and reproductive success. To learn more head to Victoria University’s article on Phys.Org https://phys.org/news/2024-08-reef-fish-moon-sex-offspring.html#google_vignette