Response of the Coral Associated Nitrogen Fixing Bacteria Toward Elevated Water Temperature

Abstract

Abstract:Coral reefs are among the most biologically diverse and economically important ecosystem on the planet. Despite the importance, reef habitat is being under threat from human exploitation, and its most serious stressor is increasing seawater temperature, an aftermath of global warming phenomenon. The increasing seawater temperature causes bleaching, diseases and insufficiency of nutrients of corals. Despite being surrounded by ocean waters were nutrient are in short supply, the reef ecosystem is a significant source of new nitrogen. Biological nitrogen fixation is a significant internal source of marine organism. The growth of all organism lies on the availability of mineral nutrients particularly of nitrogen (N 2 ). Approximately 80% of atmosphere is made of nitrogen, however, N 2 can only be available for use by organism unless it undergoes a process of nitrogen fixation. In this aspect, related literature on biological nitrogen fixation seems sparse especially on the effects of increasing seawater temperature, a well-known contributing factor of coral bleaching. In this study, an investigation was conducted on nitrogen fixing bacterial communities associated in the coral Acropora digitifera, exploring its responses towards elevated water temperature. The study shows that exposure to high temperature causes a drastic change in the community of nitrogen fixing bacteria which are abundant in coral mucus. These changes, is correlated with the shift in the metabolic function in coral holobiont, thus, affecting both health and resiliency of corals. Overall, the finding highlights the impact of elevated seawater temperature on the nitrogen fixing bacterial composition and its diversity as well as its effects of this on host metabolism.

Recovery patterns of the coral microbiome after relief of algal contact

“…In the first phase, from day 0 to 10, the relative increase in Rhodovibrionales (Alphaproteobacteria) and Desulfovibrionales (Deltaproteobacteria) could be an adaptation to change in light and oxic conditions in the still bleached coral tissue that favors anaerobic metabolisms such as sulfate reduction and nitrogen fixation (Diaz, 2017;McDevitt-Irwin et al, 2017;Rodríguez-Román et al, 2006). The average increase of Bacteroidales may indicate increased susceptibility to coral disease, while Thalassobaculales may herald an increase in zooxanthellae.…”