Title: Gametogenesis and reproductive pattern of the reef-building coral Acropora pulchra in Mo’orea, French Polynesia
Journal: TBD
Sexual reproduction is among the most important biological phenomena required for establishing coral populations which ensures reef replenishment, maintenance, and structural complexity. Despite the critical importance of gametogenesis in facilitating the transmission of phenotypes and optimally adapted physiology to subsequent generations, the timing and stages of gametogenesis are still understudied in many coral species. My proposed work will generate an in-depth, integrative dataset for both oogenesis and spermatogenesis within an ecologically important species in Moorea, French Polynesia, Acropora pulchra. We collected 40 samples of A. pulchra each month from December 2021 through October 2022 from 5 patches on the lagoon reefs of the north shore of Moorea for histological, molecular, and physiological analyses. Physiological analysis reveals seasonal variation in symbiont metrics and biomass metrics. During the austral summer in Moorea, when rainfall is higher and more frequent and temperatures increase with the thermal maximas occurring in the April and May months, we see symbiont densities, chlorophyll-a, chlorophyll-c2 content, host protein, and holobiont protein are at their lowest during this seasonal period. While during the austral winters in Moorea bring cooler temperatures and less rain, we see a peak in symbiont densities in August and a peak in chlorophyll-a during June. We also see peaks in host and holobiont protein and chlorophyll-c2 content in January, which is the beginning of austral summer in Moorea, characterized by large storms. Histological data indicates that oogenesis starts as early as December and spermatogenesis in A. pulchra follows ~five months later, with spermaries becoming visible in May, five months before release in October 2022. Further, these data are the first to show potential stages of oogenesis and spermatogenesis in A. pulchra. During Stage I oogenesis, there is development of oocytes enveloped in the mesoglea with visible nucleus and nucleolus forming (December to March), followed by Stage II in which the cytoplasm and nucleus increase in size and there starts to be an accumulation of vesicles (March to May). During Stage III the oocytes migrate into the mesoglea of the mesentary and there is accumulation of yolk in the cytoplasm (May to July). Following Stage III, Stage IV the oocytes increase in size dramatically and the yolk becomes homogeneous in the cytoplasm (July to August). Our histological data shows that spermatogenesis begins in May, where primordial spermary cells migrate into the mesoglea in Stage I (May). During Stage II, spermaries begin to show clusters of spermatocytes and nuclei peripherally aligned around them (June to July), which is then followed by the peripheral arrangement of spermatocytes and prominent central lacunae during Stage III (August). Further histological samples are being processed up until spawning in October 2022 and molecular analyses are ongoing.
Link: TBD
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