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Monitoring Tropical Signals in the Tabarca Island MPA. Anthozoans as global warming indicators

Andres Izquierdo-Muñoz1*, Esther Rubio-Portillo2 and Alfonso A. Ramos-Esplá1, 3
  • 1 Research Marine Centre, University of Alicante, Spain
  • 2 Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Spain
  • 3 Departamento de Ciencias del Mar y Biología Aplicada, Universidad de Alicante, Spain

Introduction: In the last decade marine heatwaves are becoming more frequent (Rivetti et al. 2014; Oliver et al. 2018). Anthozoans (as corals and gorgonians) are very sensitive to warming events, since its tissues suffer from bleaching and even necrosis if the event is continuated in time, so this species have proven to be good indicators (Verdura et al. 2019). Previous marine heatwaves showed high damage in gorgonians and corals populations along the Marine protected area of Tabarca Island (Rubio-Portillo et al 2015). Here, we study the shallow (-3 meters) and medium depth (-25) anthozoans populations after the summer months in 2017 and 2018, together with seawater temperature tracking. Material & Methods We followed two different methodologies for gorgonian and coral sampling: - Hard corals: Oculina patagonica and Cladocora caespitosa colonies were monitored by free diving photography. - Gorgonians: Scuba diving censuses were used to sample gorgonian communities (Eunicella spp and Leptogorgia sarmentosa colonies). In hard corals, percentages of bleaching, necrosis and covering by other species (that show old necrotic parts) were calculated; in gorgonians the percentage of necrosis and covering were estimated. In situ temperature data were collected hourly at 5 and 25 m depth (from spring to early winter) by temperature data loggers (HOBO ProV2). Results Seawater temperature records showed no extreme events during 2017 nor 2018 (as happened in 2015, for example). Maximum temperature at 5 m depth was reached in mid-August (2017, 28’79ºC and 2018 with 28’98ºC). Seasonal thermocline at 25 meters depth has different trends from two years: in 2017 a temperature peak at mid-august was detected, and then it was reduced progressively; in 2018 temperature stayed lower, and only after the second week of september the temperature raised to 27ºC. Figure 1 Bleaching in shallow corals, measured as % of individuals affected and % of surface affected, was similar for the two species studied in both years. In 2018, both species were more affected by bleaching than the previous year. Coral necrosis (tissue death) was strongly different between species and years. In 2017 O. patagonica showed medium affection of necrosis with low affected surface, and C. caespitosa had low affection of necrosis, but the colonies affected showed medium to high surface death. However, in 2018 necrosis values were lower in both species. About covering by other species (usually macroalgae), results were dramatically different. O. patagonica had low affection in 2017 and medium in 2018. C. caespitosa had high affection in 2017 and in 2018 all colonies sampled showed some parts covered by macroalgae. In both years, O. patagonica showed more recovering capacity, having more fitness to survive after bleaching or necrosis events. This feature would be one of the reasons of the invasion success of this species in the MPA (Rubio-Portillo et al 2014). Other affected hard coral has been Phyllangia mouchezii, although the data has been insufficient to determine the degree of injury as a consequence of heat stress, due to the rarity of this species (Rubio-Portillo et al., 2016). Figure 2 In the case of medium depth gorgonian communities, no apparent necrosis was observed during fall sampling in 2017 and 2018. Only few specimens had burned tips and covered parts (due to past years mortalities), but in general sea fans showed healthy status. In 2018, there was a temperature abnormality in September, with the seasonal thermocline affecting the gorgonian community along this month and October (with temperatures near 27ºC). We repeated the census in December, and at this time near the 20% of the gorgonians surface showed tissue damage.

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References

Oliver, E.C.J., Donat, M.G., Burrows, M.T., Moore, P.J., Smale, D.A., Alexander, L.V., Benthuysen, J.A., Feng, M., Sen Gupta, A., Hobday, A.J., Holbrook, N.J., Sarah, E., Perkins-Kirkpatrick, S.E., Scannell, H.A., Sandra, C., Straub, S.C., Wernberg, T. (2018). Longer and more frequent marine heatwaves over the past century. Nat. Commun. 9:1324. Rivetti, I., Fraschetti, S., Lionello, P., Zambianchi, E., Boero, F. (2014). Global Warming and Mass Mortalities of Benthic Invertebrates in the Mediterranean Sea. Plos ONE 23: 1-22. Rubio-Portillo, E., Vázquez-Luis, M., Izquierdo-Muñoz, A., Ramos-Esplá, A. A. (2014). 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., Izquierdo-Muñoz, A., Gago, J. F., Rosselló-Mora, R., Antón, J., Ramos-Esplá, A. A. (2016). Effects of the 2015 heat wave on benthic invertebrates in the Tabarca Marine Protected Area (southeast Spain). Mar Environ Res 122, 135-142. Verdura, J., Linares, C., Ballesteros, E., Coma, R., Uriz, M.J., Bensoussan, N., Cebrian, E. (2019). Biodiversity loss in a Mediterranean ecosystem due to an extreme warming event unveils the role of an engineering gorgonian species. Scientific Reports 9: 5911

Keywords: Global Warming, Gorgonian communities, corals, Bioindicator, temperature

Conference: XX Iberian Symposium on Marine Biology Studies (SIEBM XX) , Braga, Portugal, 9 Sep - 12 Sep, 2019.

Presentation Type: Poster Presentation

Topic: Global Change, Invasive Species and Conservation

Citation: Izquierdo-Muñoz A, Rubio-Portillo E and Ramos-Esplá AA (2019). Monitoring Tropical Signals in the Tabarca Island MPA. Anthozoans as global warming indicators. Front. Mar. Sci. Conference Abstract: XX Iberian Symposium on Marine Biology Studies (SIEBM XX) . doi: 10.3389/conf.fmars.2019.08.00124

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Received: 07 Jun 2019; Published Online: 27 Sep 2019.

* Correspondence: Mx. Andres Izquierdo-Muñoz, Research Marine Centre, University of Alicante, Santa Pola, 03690, Spain, andres.izquierdo@ua.es