Abstract
Recent research indicates that synchronicity of sexual reproduction in coral spawning events is breaking down, leading to aging populations and decreased recruitment success. In this perspective, we develop a hypothesis that this phenomenon could be caused by ongoing ocean acidification (OA). We hypothesize, that the underlying physiological machinery could be the carbon concentrating mechanism (CCM). The endosymbiotic zooxanthellae of corals could use this mechanism to sense calm water motion states in a comparable way to that known from macroalgae. In macroalgae, it is well-established that dissolved inorganic carbon (DIC) acts as the trigger for signaling low water motion. Hence, evolutionarily developed signals of low water motion, suited for gamete-release, may be misleading in the future, potentially favoring opportunistic species in a broad range of marine organisms.
Highlights
In their recent paper, Shlesinger and Loya [1] describe the breakdown of Red Sea coral spawning synchrony
Whether or not the observed loss of spawning synchrony can be transferred to other reef systems worldwide and how the present data can be related to historical data [2], Shlesinger and Loya [1] undoubtedly showed that coral species in the Gulf of Eilat/Aqaba do not show a high spawning synchrony
The ecological consequences are very relevant, but the central questions are, if this applies to other organisms and their release of gametes, algae and how climate change could be responsible for the observed low spawning synchrony
Summary
Shlesinger and Loya [1] describe the breakdown of Red Sea coral spawning synchrony. Diversity 2020, 12, 241 point of many marine organisms ensuring genetic connectivity and the long-time persistence of species (e.g., [7,8,9]), but spawning events must be synchronized to ensure appropriate gamete concentrations [7]. Within the range set by the lunar cycle, the exact day or even hour of gamete release apparently depends on the agitation state of the seawater around macroalgae [5,6] The latter is described for macroalgae [5], but likely comparable to corals, a very different taxon, releasing its gametes at preferably calm water conditions [10], whose spawning events can be delayed by strong winds [11].
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