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bioRxiv · 10.1101/2023.10.05.558016

Pocillopora meandrina daytime broadcast spawning in Moorea, French Polynesia

Harnay, P.·Putnam, H. M.
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Abstract

Knowledge of coral gamete release is fundamental to reef ecology and evolution, but cryptic species complicate reproduction studies. In Moorea, French Polynesia, when corals were decimated by crown-of-thorns and a cyclone between 2007-2010, recruitment of six cryptic species of Pocillopora spp. primarily drove decadal reef recovery. Broadcast spawning for these genetically-verified species at Moorea is, however, undocumented in the scientific literature. We conducted in situ surveys over 58 days during September 2022-January 2023, October 2023-January 2024, and October 2024-December 2024. To identify the Pocillopora spp. we used molecular analysis of mtORF and PocHistone markers. P. meandrina and P. grandis spawned 2-3 days following the full moons of October-December. In contrast, P. verrucosa and P. tuahiniensis spawned at the new moons in November-December, with P. verrucosa spawning on lunar days 0-1, and P. tuahiniensis spawning on lunar days 1-3. Diel offset in the timing of spawning following sunrise was present in both moon phases indicating a temporal speciation barrier. P. verrucosa spawned [~]45 min after sunrise, whereas P. tuahiniensis spawned [~]73 min after sunrise. Similarly, P. grandis spawned [~]40 minutes after sunrise, whereas P. meandrina spawned [~]65 minutes after sunrise. Only one colony of P. effusa spawned (lunar day 3 new moon [~]06:30-06:50), requiring further confirmation of the timing for this low abundance species. Collectively, these first spawning reports provide an initial scientific documentation of Pocillopora spawning at the genetically-verified species level in Moorea, increasing capacity to study the essential process of coral reproduction for critical reef building species. Data, Code, Image Archive: https://osf.io/5geqd/ ResumeLa connaissance de la liberation des gametes chez les coraux est fondamentale pour comprendre lecologie et levolution des recifs, mais la presence despeces cryptiques complique les etudes sur la reproduction. A Moorea, en Polynesie francaise, lorsque les coraux ont ete decimes par des etoiles de mer couronne depines et un cyclone entre 2007 et 2010, le recrutement de six especes cryptiques de Pocillopora spp. a principalement contribue a la recuperation des recifs au cours de la decennie suivante. Toutefois, la reproduction par emission synchronisee des gametes (broadcast spawning) de ces especes genetiquement verifiees a Moorea na pas encore ete documentee dans la litterature scientifique. Nous avons mene des observations in situ sur 58 jours entre septembre 2022 et janvier 2023, doctobre 2023 a janvier 2024, puis doctobre a decembre 2024. Pour identifier les especes de Pocillopora spp., nous avons utilise une analyse moleculaire des marqueurs mtORF et PocHistone. P. meandrina et P. grandis ont pondu 2 a 3 jours apres les pleines lunes doctobre a decembre. En revanche, P. verrucosa et P. tuahiniensis ont pondu lors des nouvelles lunes en novembre et decembre, P. verrucosa aux jours lunaires 0 a 1, et P. tuahiniensis aux jours lunaires 1 a 3. Un decalage journalier dans le moment de la ponte apres le lever du soleil a ete observe pour les deux phases lunaires, indiquant une barriere temporelle de speciation. P. verrucosa a pondu environ 45 minutes apres le lever du soleil, tandis que P. tuahiniensis a pondu environ 73 minutes apres. De maniere similaire, P. grandis a pondu environ 40 minutes apres le lever du soleil, alors que P. meandrina a pondu environ 65 minutes apres. Une seule colonie de P. effusa a pondu (jour lunaire 3, nouvelle lune, entre [~]06:30 et 06:50), ce qui necessite une confirmation supplementaire du moment de reproduction pour cette espece peu abondante. Collectivement, ces premieres observations de ponte constituent une premiere documentation scientifique de la reproduction des Pocillopora au niveau des especes genetiquement verifiees a Moorea, augmentant la capacite a etudier ce processus essentiel de reproduction chez des especes cles pour la construction des recifs.

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Harnay, P., Putnam, H. M.. 2023-10-06. Pocillopora meandrina daytime broadcast spawning in Moorea, French Polynesia. https://doi.org/10.1101/2023.10.05.558016

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