Loss of coral reproductive synchrony
Synchrony of reproduction is an important strategy used by both terrestrial and marine organisms to maximize their reproductive success. Depending on the ecological context, synchronization of reproduction may offer advantages in increasing fertilization success, reducing predation through “swarming”, and ability to locate mates.
Timing of reproduction and large reproductive events in a population is dependent on the “clock” set by environmental cues, such as temperature, chemical cues, irradiance, lunar cycles, tides, wind or current patterns, and timing of sunrise or sunset. In the marine environment, many species of reef-building stony corals reproduce through mass spawning events. These events generally occur within a narrow window of time in which coral colonies have the opportunity to release their gametes into the water column to fertilize. Each species of coral that reproduces in this way has a specialized strategy for timing of reproduction that is tightly related to the local environmental conditions. As corals are not capable of moving to locate potential mates, mass spawning events are an important strategy in allowing for successful reproduction and recruitment of new individuals to reefs.
However, because reproductive synchrony is dependent on environmental cues, shifts in water temperature, chemistry, and quality as a result of global climate change and local anthropogenic impacts present a threat to the stability of mass spawning. A new study published today in the journal, Science, reports on timing of reproduction in several species of corals in the Red Sea over a four-year period.
Across several species, the authors found a significant loss and disruption of reproductive synchrony in parallel laboratory and field observations compared to historical data. This loss of coordination among corals was documented at reefs both close to and far from human population centers. For corals, a loss of synchrony during such a small window of opportunity suggests fertilization will decrease, ultimately resulting in a lower supply of new larvae and recruits to the reef.
In the face of a collection of threats to coral reefs, the disruption to reproductive timing, a foundational ecological process, poses a serious threat to coral reef persistence. Wider monitoring and long-term study of coral reproduction patterns in reefs around the globe is necessary to understand how corals are responding to a change in the environment.
Read an additional article on this study here:
Shlesinger T and Y Loya (2019) Breakdown in spawning synchrony: A silent threat to coral persistence. Science 365 (6457):1002-1007.