Impact of envionmental changes on Oculina patagonica coral holobiont

Abstract

Event Abstract Back to Event Impact of envionmental changes on Oculina patagonica coral holobiont Esther Rubio-Portillo1*, Josefa Antón1 and Alfonso A. Ramos-Esplá1 1 Universidad de Alicante, Spain Introduction Scleractinian corals can be considered as a small ecosystem that is made up of the coral, its endosymbiotic zooxanthellae and associated community of microorganisms (bacteria, archaea, fungi and virus), which form a collaborative consortium known as the coral holobiont (Knowlton and Rohwer, 2003). Shifts in any of these partners can compromise the health of the whole animal. Thus, to understand coral diseases it is necessary an in-depth knowledge of coral holobiont–environment interactions, pathology and factors that promote the virulence of the possible causative agents. Diseases have been identified as one of the major contributor to decline in corals worldwide. Whether these reported diseases are a result of pathogens or changing environmental conditions is a current topic of debate (Harvell et al., 2007). It is well known that a relationship exists between global warming and the proliferation of Vibrio spp., particularly and accordingly a rise of Vibrio-associated coral diseases. Bleaching of the coral Oculina patagonica was first observed at the Israeli coast in 1993 and it was shown that Vibrio shilonii (=Vibrio mediteranei) was the causative agent (Kushmaro et al., 2001). However, there is a considerable controversy on the nature of its principal cause, due to the different existing hypothesis about whether microorganisms have or not a role in the bleaching process. The present work is a summary of results obtained from different studies that were carried out to improve the knowledge about the response of the coral O. patagonica and its microbial community to different environmental conditions, as well as to elucidate the role of Vibrio spp. and environmental factors in bleaching events, particularly in the global warming scenario. Material and Methods The distribution patterns of O.patagonica were studied by snorkeling along the rocky coast of Valencian Region (East of Spain) in 2010 in order to understand the environmental factors contributing to its current increase in this area (Rubio-Portillo et al., 2014a). Furthermore, to study the response of this species under different environmental conditions, field data on colony growth and bleaching were obtained for a period of 18 months (June 2010-December 2011) in two different sampling locations: Alicante Harbour and the Marine Protected Area (MPA) of Tabarca (Rubio-Portillo et al., 2014b). Concurrently to the field work, the temporal and spatial dynamics of culturable Vibrio spp. assemblages associated to O.patagonica were studied (Rubio-Portillo et al., 2014c) and molecular (denaturing gradient gel electrophoresis and next generation sequencing Illumina MiSeq), and microscopic techniques were applied to describe the bacterial associated community. Finally, the pathogenic potential Vibrio coralliilyticus and V. mediterranei over O.patagonica was studied by experimental infection at three different temperatures (20, 24 and 28ºC) under laboratory conditions (Rubio-Portillo et al., 2014c). Results and Discussion The factors that largely determine the presence of this species were the distance from the nearest harbour and the benthic macroalgae community that determines its recruitment, which seems to be favored by filamentous algae turfs. Therefore, the increase of anthropogenic disturbances over coastal ecosystems could be providing new spreading areas for O. patagonica (Rubio-Portillo et al., 2014a). Moreover, it should be noted that this coral specie is able to bear different environmental conditions such as ultraviolet radiation, water salinity, turbidity, hidrodynamism and pollution. In fact, by monitoring marked colonies during 18 months, we demonstrated that this species shows similar growth rates in eutrophic and turbid environments (Alicante Harbour) than in oligotrophic and clear ones (MPA of Tabarca) (Rubio-Portillo et al., 2014b). The seawater temperature is the factor with the highest influence over O. patagonica growth, which showed a minimum during cold months (February, 13ºC) and an enhancement during warm months (June to September, 18-28ºC). However, when seawater temperatures were maintained over 26ºC for a prolonged period of time, not only O. patagonica growth rates decreased considerably but bleaching reached the maximum percentages, as observed in the MPA of Tabarca during summer 2011. Environmental variables not only have an effect over coral host but also over its bacterial communities, which were different among coral compartments, and coral tissue was the one that best showed changes related to environmental conditions and coral health status. Pseudovibrio genus was mainly related to healthy corals and cold months while Vibrio genus was associated with warm months and mainly with unhealthy corals. Furthermore, sequences related to Vibrio coral pathogens, such as V. mediterranei and V. coralliilyticus, were recovered by culture methods only from unhealthy corals but were also detected by Illumina sequencing in healthy specimens during cold months, suggesting that these pathogens could be in viable but non-culturable state in the coral tissues. Finally, the pathogenic potential of V. mediterranei and V. coralliilyticus over O. patagonica has been demonstrated (Rubio-Portillo et al., 2014c). Both pathogens began to produce disease signs in corals at 24ºC, which were more evident at 28ºC, confirming that seawater temperature is one of the main factors involved in the onset of coral diseases. Interestingly, when these pathogens were inoculated together, corals developed disease signs faster, even when maintained at 20ºC, showing a possible synergic effect between both pathogens. References Harvell, D., Jordán-Dahlgren, E., Merkel, S., Rosenberg, E., Raymundo, L., Smith, G., et al. (2007). Coral disease, environmental drivers, and the balance between coral and microbial associates. Oceanography, 20, 172-195. Knowlton, N., Rohwer, F. (2003). Multispecies microbial mutualisms on coral reefs: the host as a habitat. Am Nat, 162(S4), S51-S62. Kushmaro, A., Banin, E., Loya, Y., Stackebrandt, E., Rosenberg, E. (2001). Vibrio shiloi sp. nov., the causative agent of bleaching of the coral Oculina patagonica. Int J Syst Evol Micr, 51(4), 1383-1388. Rubio-Portillo, E., Vazquez-Luis, M; Izquierdo Muños, A; Ramos-Esplá, A. A. (2014a). Distribution patterns of alien coral Oculina patagonica De Angelis D’Ossat, 1908 in western Mediterranean Sea. J Sea Res, 85, 372–378. Rubio-Portillo, E., Vázquez-Luis, M., Valle, C., Izquierdo-Muñoz, A., Ramos-Esplá, A. A. (2014b). Growth and bleaching of the coral Oculina patagonica under different environmental conditions in the western Mediterranean Sea. Marine Biology, 161(10), 2333-2343. Rubio-Portillo, E., Yarza, P., Peñalver, C., Ramos-Esplá, A. A, Antón, J. (2014c). New insights into Oculina patagonica coral diseases and their associated Vibrio spp. Keywords: Global Warming, Coral diseases, Vibrio Infections, Mediterranean Sea, Oculina patagonica Conference: XIX Iberian Symposium on Marine Biology Studies, Porto, Portugal, 5 Sep - 9 Sep, 2016. Presentation Type: Poster Presentation Topic: 2. GLOBAL CHANGES, INVASIVE SPECIES AND CONSERVATION Citation: Rubio-Portillo E, Antón J and Ramos-Esplá AA (2016). Impact of envionmental changes on Oculina patagonica coral holobiont. Front. Mar. Sci. Conference Abstract: XIX Iberian Symposium on Marine Biology Studies. doi: 10.3389/conf.FMARS.2016.05.00181 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 29 Apr 2016; Published Online: 03 Sep 2016. * Correspondence: Dr. Esther Rubio-Portillo, Universidad de Alicante, Alicante, Alicante, 03690, Spain, esther.portillo@ua.es Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Esther Rubio-Portillo Josefa Antón Alfonso A Ramos-Esplá Google Esther Rubio-Portillo Josefa Antón Alfonso A Ramos-Esplá Google Scholar Esther Rubio-Portillo Josefa Antón Alfonso A Ramos-Esplá PubMed Esther Rubio-Portillo Josefa Antón Alfonso A Ramos-Esplá Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.