Do tides equally influence the reproductive cycle of two symbiotic estuarine shrimp?

Individuals within a population may reproduce synchronously. This phenomenon can occur in response to endogenous and/or exogenous stimuli and to different selective pressures. The objective of this study was to investigate whether there is reproductive synchrony with the tidal cycle in populations of two species of symbiotic estuarine shrimps (Alpheus estuariensis and Salmoneus carvachoi). We calculated the Embryonic Stage Index (ESI) and the Gonadal Stage Index (GSI) to investigate evidence of reproductive synchrony with the tidal lunar cycle. We also performed a correspondence analysis to assess the correlation between the lunar phase and both the ESI and GSI in each species. Moreover, we conducted a cross-correlation analysis using a time series of tidal range vs. GSI (lagged variable) and tidal range vs. ESI (lagged variable). The results suggest that larval release in A. estuariensis occurs during the spring tides of the rainy season, and that mating takes place independently of the tidal cycle. On the other hand, tidal variations influenced both the timing of larval release and mating in S. carvachoi. In both populations, embryo development accompanies gonadal development, resulting in successive spawning. We suggest that osmotic stress is the selective pressure that affects the larval release behavior of A. estuariensis. In contrast, both predation and osmotic stress may act synergistically on S. carvachoi. Finally, we conclude that although both populations occupy the same habitat and are exposed to the same environmental influences, they exhibit distinct reproductive patterns.

Automated summary

This study investigated the reproductive synchrony with the tidal cycle in two species of symbiotic estuarine shrimps. The results showed that larval release in A. estuariensis is synchronized with the spring tides of the rainy season, while mating occurs independently of the tidal cycle. In contrast, tidal variations influenced both the timing of larval release and mating in S. carvachoi. Osmotic stress appears to be the main selective pressure affecting the reproductive behavior of A. estuariensis, while both predation and osmotic stress may act on S. carvachoi.