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1. Effect of Substratum Structural Complexity of Coral Seedlings on the Settlement and Post-Settlement Survivorship of Coral Settlers

Author

Shuichi Fujiwara, Daisuke Kezuka, Kazutaka Hagiwara, Hiroo Ishimori, and Hideo Tabata

Subjects
substratum, structural complexity, sexual propagation, larval settlement, survivorship, coral seedling, Oceanography, GC1-1581
Abstract

The substratum structure is critical for facilitating settlement and increasing the survivorship of coral settlers. However, knowledge about its structural complexity is largely lacking. In this study, we examined the effect of complexity on the settlement and post-settlement survivorship of coral settlers using four types of structures: groove, using a CSD (Coral Settlement Device, 4.5 cm φ × 2.5 cm H, top-shaped ceramic); flat, using a CP (Ceramic Plate, 29.5 cm L × 3.1 cm W × 0.9 cm H, unglazed ceramic plate); linear, using a CN (Coral Net, mesh size 19 mm, biodegradable plastic net); and wrinkle, using a SS (Scallop Shell, 11.0 cm in shell length). The complexity was obtained from the ratio of the surface area to the vertically projected area of the substratum. The substratum sets were installed in the coral reef around the Ryukyu Islands every May from 2012 to 2014. After about 2 or 6 months of spawning, a certain number of substratum types were sampled, and the number of coral spats that settled on them was counted by taxa classified into Acropora, Pocilloporidae, Millepora, and Others. The larval settlement rate in the first set of samples and the survivorship of coral spats in the second set of samples were estimated. The mean settlement rate was, in order, the CSD; SS; CN; and CP, and the mean survivorship was, in order, the CSD; CP; SS; and CN, over three years. A positive correlation was found between the structural complexity, mean settlement rate, and mean survivorship. Our results show that the structural complexity of coral seedlings affects the settlement of coral larvae and the survivorship of coral spats.

Published
2022
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2. Color morphs of the coral, Acropora tenuis, show different responses to environmental stress and different expression profiles of fluorescent-protein genes

Author

Daisuke Kezuka, Koji Kinjo, Noriyuki Satoh, Kohei Shintaku, Kanako Hisata, Hiroo Ishimori, Yuna Zayasu, Mayumi Kawamitsu, Chuya Shinzato, Kazutaka Hagiwara, Koji Koizumi, and Atsushi Yokokura

Subjects
AcademicSubjects/SCI01140, 0106 biological sciences, animal structures, genetic structures, AcademicSubjects/SCI00010, Coral, ved/biology.organism_classification_rank.species, Zoology, Biology, AcademicSubjects/SCI01180, 01 natural sciences, Acroporidae, Green fluorescent protein, 03 medical and health sciences, Stress, Physiological, Okinawa coast, Genetics, Animals, Symbiosis, Molecular Biology, Gene, Reef, Acropora tenuis, Ecosystem, reproductive and urinary physiology, Genetics (clinical), 030304 developmental biology, Investigation, 0303 health sciences, geography, geography.geographical_feature_category, Coral Reefs, coral symbionts, Host (biology), ved/biology, fluorescent protein gene expression, 010604 marine biology & hydrobiology, fungi, color morphs, thermal stress response, Coral reef, Anthozoa, biology.organism_classification, Dinoflagellida, AcademicSubjects/SCI00960, psychological phenomena and processes
Abstract

Corals of the family Acroporidae are key structural components of reefs that support the most diverse marine ecosystems. Due to increasing anthropogenic stresses, coral reefs are in decline. Along the coast of Okinawa, Japan, three different color morphs of Acropora tenuis have been recognized for decades. These include brown (N morph), yellow green (G), and purple (P) forms. The tips of axial polyps of each morph exhibit specific fluorescence spectra. This attribute is inherited asexually, and color morphs do not change seasonally. In Okinawa Prefecture, during the summer of 2017, N and P morphs experienced bleaching, in which many N morphs died. Dinoflagellates (Symbiodiniaceae) are essential partners of scleractinian corals, and photosynthetic activity of symbionts was reduced in N and P morphs. In contrast, G morphs successfully withstood the stress. Examination of the clade and type of Symbiodiniaceae indicated that the three color-morphs host similar sets of Clade-C symbionts, suggesting that beaching of N and P morphs is unlikely attributable to differences in the clade of Symbiodiniaceae the color morphs hosted. Fluorescent proteins play pivotal roles in physiological regulation of corals. Since the A. tenuis genome has been decoded, we identified five genes for green fluorescent proteins (GFPs), two for cyan fluorescent proteins (CFPs), three for red fluorescent proteins (RFPs), and seven genes for chromoprotein (ChrP). A summer survey of gene expression profiles under outdoor aquarium conditions demonstrated that (a) expression of CFP and REP was quite low during the summer in all three morphs, (b) P morphs expressed higher levels of ChrP than N and G morphs, (c) both N and G morphs expressed GFP more highly than P morphs, and (d) GFP expression in N morphs was reduced during summer whereas G morphs maintained high levels of GFP expression throughout the summer. Although further studies are required to understand the biological significance of these color morphs of A. tenuis, our results suggest that thermal stress resistance is modified by genetic mechanisms that coincidentally lead to diversification of color morphs of this coral.

Published
2021
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3. Color morphs of the coral, Acropora tenuis, show different responses to environmental stress and different expression profiles of fluorescent-protein genes

Author

Noriyuki, Satoh, Koji, Kinjo, Kohei, Shintaku, Daisuke, Kezuka, Hiroo, Ishimori, Atsushi, Yokokura, Kazutaka, Hagiwara, Kanako, Hisata, Mayumi, Kawamitsu, Koji, Koizumi, Chuya, Shinzato, Yuna, Zayasu, Noriyuki, Satoh, Koji, Kinjo, Kohei, Shintaku, Daisuke, Kezuka, Hiroo, Ishimori, Atsushi, Yokokura, Kazutaka, Hagiwara, Kanako, Hisata, Mayumi, Kawamitsu, Koji, Koizumi, Chuya, Shinzato, and Yuna, Zayasu

Abstract

Corals of the family Acroporidae are key structural components of reefs that support the most diverse marine ecosystems. Due to increasing anthropogenic stresses, coral reefs are in decline. Along the coast of Okinawa, Japan, three different color morphs of Acropora tenuis have been recognized for decades. These include brown (N morph), yellow green (G), and purple (P) forms. The tips of axial polyps of each morph exhibit specific fluorescence spectra. This attribute is inherited asexually, and color morphs do not change seasonally. In Okinawa Prefecture, during the summer of 2017, N and P morphs experienced bleaching, in which many N morphs died. Dinoflagellates (Symbiodiniaceae) are essential partners of scleractinian corals, and photosynthetic activity of symbionts was reduced in N and P morphs. In contrast, G morphs successfully withstood the stress. Examination of the clade and type of Symbiodiniaceae indicated that the three color-morphs host similar sets of Clade-C symbionts, suggesting that beaching of N and P morphs is unlikely attributable to differences in the clade of Symbiodiniaceae the color morphs hosted. Fluorescent proteins play pivotal roles in physiological regulation of corals. Since the A. tenuis genome has been decoded, we identified five genes for green fluorescent proteins (GFPs), two for cyan fluorescent proteins (CFPs), three for red fluorescent proteins (RFPs), and seven genes for chromoprotein (ChrP). A summer survey of gene expression profiles under outdoor aquarium conditions demonstrated that (a) expression of CFP and REP was quite low during the summer in all three morphs, (b) P morphs expressed higher levels of ChrP than N and G morphs, (c) both N and G morphs expressed GFP more highly than P morphs, and (d) GFP expression in N morphs was reduced during summer whereas G morphs maintained high levels of GFP expression throughout the summer. Although further studies are required to understand the biological significance of these color, source:https://academic.oup.com/g3journal/article/11/2/jkab018/6114454

Published
2021

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