The role of intertidal egg deposition on survival of the puffer, Takifugu niphobles (Jordan et Snyder), embryos

The puffer, Takifugu niphobles (Jordan et Snyder), is an intertidal spawner; the spawning linkage with the tidal cycle makes it possible for the puffer to spawn at the upper intertidal zone. To test whether the intertidal spawning is an adaptation to maximize egg survival, the location of egg deposition and the most suitable location for egg survival were determined. An egg-trap experiment indicated that eggs were scattered around the spawning zone and never moved downwards into the lower intertidal zone. The eggs were stranded under pebbles of the upper intertidal zone, acid developed there. Some of the stranded eggs died apparently because of high temperatures and desiccation during periods of exposure. An egg-transplantation experiment indicated that throughout the spawning season, mortality of eggs by physical stress was lower in the lower intertidal zone (where eggs were never found naturally) than in the upper zone. Also, the loss rate due to predation or wave action did not differ among the tidal zones. These facts suggest that the upper intertidal spawning linked with the tidal cycle does not maximize egg survival, and that the puffer should spawn during lower tides in the tidal cycles.