Journal of the Japanese Coral Reef Society
Online ISSN : 1882-5710
Print ISSN : 1345-1421
ISSN-L : 1345-1421
Volume 16, Issue 1
Displaying 1-7 of 7 articles from this issue
Editorial
Review article
  • Ryota NAKAJIMA, Yasuaki TANAKA
    2014 Volume 16 Issue 1 Pages 3-27
    Published: 2014
    Released on J-STAGE: September 02, 2014
    JOURNAL FREE ACCESS
    It is well known that corals release transparent and mucoid organic matter (coral mucus) to the ambient seawater. This mucus release is important for various physiological functions of corals such as defense against stress, particle trap and cellular metabolic regulation. Coral mucus is mainly composed of carbohydrates, proteins and lipids, of which most are dissolved organic matter and thus utilized by heterotrophic bacteria and incorporated into the microbial loop. A fraction of the mucus, with its high molecular weight and sticky properties, captures large amounts of particulate organic matter in the seawater, forming large organic aggregates which are efficiently assimilated into higher trophic levels. Thus, coral mucus is incorporated into reef organisms in a variety of processes and functions as an important organic energy source in reef systems. This article reviews some types of mucus forms, chemical composition and production rates of mucus, and the contribution of mucus to heterotrophs from biogeochemical and ecological perspectives and suggests some future works for coral mucus studies.
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  • Shihori INOUE, Asami TAKAHASHI
    2012 Volume 16 Issue 1 Pages 29-45
    Published: 2012
    Released on J-STAGE: September 02, 2014
    JOURNAL FREE ACCESS
    Coral reefs worldwide are now under threat of degradation and destruction by ocean acidification and global warming. Local anthropogenic impacts such as eutrophication and turbidity also weaken them. With the degradation of coral reefs, coral reef communities shift from an ecosystem dominated by hard coral to other organisms. Here we consider soft coral as an example of an organism that can replace hard corals in a reef community. In the Ryukyu Islands, soft coral is a typical organism found in coral reefs and is present at a high density. However, there are far fewer published studies of soft coral than of hard corals. Therefore, few studies have quantitatively assessed the potential for a community to shift from hard coral to soft coral. Many studies of hard coral can be applicable to soft coral because they have some points in common, such as their habitat and body structure. We can consider a possible or ongoing community shift in coral reefs by comparing hard and soft coral directly, using the perspectives and techniques of hard coral studies for the study of soft coral. Here we introduce the concept of community shifts in the coral reef community with regard to previous studies. We discuss the possibility and the importance of a community shift from hard to soft coral. The causes and mechanisms of the community shift are considered alongside the biological features and physical structure of soft coral. To investigate the mechanisms involved, we suggest some approaches that can be used to understand the degree of community shift occurring. Finally, we consider how the coral reef ecosystem would be affected by such a community shift. We need to undertake a multidisciplinary approach to understand the changing coral reef habitat. As an example, we suggest how to assess a community shift by collaborative studies of hard and soft coral.
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  • Tomihiko HIGUCHI, Ikuko YUYAMA, Takashi NAKAMURA
    2014 Volume 16 Issue 1 Pages 47-64
    Published: 2014
    Released on J-STAGE: September 02, 2014
    JOURNAL FREE ACCESS
    Over the past several decades, coral reef ecosystems have experienced various stresses and extensive degradation due to increased anthropogenic activity. Reef-building corals respond to stress in various ways, including bleaching. Corals exhibit defense mechanisms against stress, although many of these functions have not yet been clarified. Understanding the defense mechanisms in corals could provide important information for finding solutions to stress-related responses such as coral bleaching. The entire coral genome has recently been sequenced and this is expected to lead to breakthroughs in research on coral defense mechanisms. In this review, we describe coral bleaching, oxidative stress, antioxidants, mycosporine-like amino acids, and fluorescent proteins as responses and defense mechanisms against environmental stressors such as high temperature, strong irradiance, and ultraviolet radiation, from the perspectives of molecular biology, physiology, and ecology.
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