Observations of Simultaneous Sperm Release and Larval Planulation Suggest Reproductive Assurance in the Coral Pocillopora acuta

Abstract

Despite being an extensively studied group of corals, the reproductive biology of the scleractinian genus Pocillopora remains a mystery. Pocillopora acuta has been proposed to exhibit a mixed reproductive mode, sexually producing gametes (sperm and eggs) and asexually brooding larvae simultaneously within a single colony. Here, we report observations of night-time spawning of sperm during the peak monthly larval release period. We offer a new hypothesis for the regulation of sexual and asexual reproduction in the species and posit that sexual reproduction may occur more often than previously suggested. However, the success of internal oocyte fertilization and subsequent zygote development is dependent on sperm making contact with a fertile colony. We hypothesize that asexual development of larvae occurs when sperm is absent, but more extensive genetic, genomic, and histological data are required to determine the pathway by which unfertilized oocytes may develop. We also propose that this mixed mode of reproduction is an adaptation to mating failure, common in sessile marine invertebrates. The reproductive assurance enjoyed by the species may therefore be the key to its ecological and evolutionary persistence.

Endozoicomonas-chlamydiae interactions in cell-associated microbial aggregates of the coralPocillopora acuta

“…Here, we provide a detailed characterization of CAMAs in the coral Pocillopora acuta , including their location, subcellular structure, transmission, community composition, and functional potential (Figure S1, Table S1). Pocillopora acuta is an asexual brooder and sexual broadcast spawner coral ( 27 ). It acquires bacteria both vertically, from the mother colony, and horizontally, from the environment ( 28 ).…”

Effects of thermal conditioning on the performance of Pocillopora acuta adult coral colonies and their offspring

“…Specifically, we asked whether thermal preconditioning of adult colonies of the reef-building coral Pocillopora acuta provides a benefit to offspring when the latter are subsequently exposed to high temperature. P. acuta is a hermaphroditic species with a mixed, yet predominately brooding, reproductive strategy, with larvae produced both asexually and sexually (Yeoh and Dai 2010;Smith et al 2019). We examined the influence of adult conditioning across three critical coral life-history stages: reproduction, recruitment and recruit performance, and assessed ecological metrics that are easily measured such as larval abundance, survival, size and symbiont photochemical performance.…”

A molecular census of early‐life stage scleractinian corals in shallow and mesophotic zones

“…Recently, P. verrucosa has been found to brood in nearby Philippines (Villanueva et al., 2008) that wintertime P. verrucosa recruits could actually be brooded; however, further study is required. Several other pocilloporids can reproduce asexually, which could provide an alternative explanation for winter recruitment: Pocillopora acuta may generate planula asexually in the absence of sperm (Nakajima et al., 2018; Smith et al., 2019), and P . damicornis may produce clonal larvae, although this behavior may vary along latitudinal gradients (Miller & Ayre, 2004).…”