Modelling susceptibility of Abrolhos reefs to coral bleaching

Coral reefs suffer many threats, including coral bleaching, which occurs mainly in response to environmental variables such as positive temperature anomalies. However, there is a need to explore potential synergies between environmental and anthropogenic variables. The objective of this work is to use multi-criteria analysis to explore associations between environmental and anthropogenic variables in order to estimate in a spatially explicit way the susceptibility of the different Abrolhos reefs in Bahia, Brazil, to coral bleaching. Our results show that from 2001 to 2016 there was a sharp increase in the reef areas with higher susceptibility to bleaching. While in 2001, 20% of the reef area presented low susceptibility to bleaching and 80% showed medium susceptibility, in 2016, 19% of the area showed medium and 81% showed high susceptibility. 2016 presented the highest susceptibility among the years used in the study, suggesting a higher percentage of bleached colonies, which is corroborated by the fact that this year was considered by NASA and NOAA as the hottest year since 1880. Results also show that bleaching pattern is spatially differentiated. The reefs from the coastal arch of Abrolhos present the greater susceptibility to bleaching. Exception is Timbebas reefs which, although located in the coastal arch, are more similar to the outer arch reefs, wich are less susceptible to bleaching

Suscetibilidade dos recifes de Abrolhos aos eventos de branqueamento de corais

Exportado OPUSMade available in DSpace on 2019-08-13T10:36:10Z (GMT). No. of bitstreams: 1 dissertacao_samira_sabadini_final.pdf: 2881870 bytes, checksum: 99496626fab0ef21da49268ec5f764c8 (MD5) Previous issue date: 11Os ecossistemas marinhos são fundamentais para a manutenção da vida na Terra. Dentre eles, destacam-se os recifes de corais que são considerados altamente produtivos, diversos e complexos. No entanto, esses ecossistemas sofrem muitas ameaças, dentre elas o branqueamento de corais. O branqueamento ocorre, principalmente, como resposta a anomalias positivas de temperatura da superfície do mar. Esse trabalho teve como objetivo geral modelar a suscetibilidade dos recifes de Abrolhos (sul da Bahia) sofrerem branqueamento e, mais especificamente, gerar um mapa de suscetibilidade de branqueamento dos recifes de Abrolhos durante os verões de 2001, 2002, 2003, 2005 e 2016. Nossos resultados mostram que em 2001, 20% da área recifal apresentou baixa suscetibilidade ao branqueamento, enquanto 80% apresentou suscetibilidade média. 2002 foi o ano com menor suscetibilidade, sendo muito baixa em 18% da área e baixa em 82%. Em 2003, 75% da área mostrou baixa suscetibilidade e 25% média. Em 2005, a área de média suscetibilidade atingiu 90%, enquanto 10% apresentou baixa suscetibilidade. Em 2016, 19% da área apresentou média e 81% alta suscetibilidade. O ano de 2016 apresentou a maior suscetibilidade entre os anos estudados, sugerindo uma maior porcentagem de colônias branqueadas, o que é corroborado pelo fato de que este ano foi considerado pela NASA e NOAA como o ano mais quente desde 1880. Os resultados também mostram que o padrão de branqueamento é espacialmente diferenciado. Os recifes de abrolhos pertencentes ao arco costeiro apresentam maior suscetibilidade ao branqueamento. Exceção é feita aos recifes de Timbebas que, embora localizados no arco costeiro, são mais semelhantes aos recifes do arco externo que são menos suscetíveis ao branqueamento.Marine ecosystems are fundamental to the maintenance of life on Earth. Among them, the coral reefs that are considered highly productive, diverse and complex stand out. However, these ecosystems suffer many threats, including coral bleaching. Bleaching occurs mainly in response to positive sea surface temperature anomalies. The objective of this work was to model the susceptibility of Abrolhos reefs (southern Bahia) to bleaching and, more specifically, to generate a map of susceptibility to bleaching of Abrolhos reefs during the summers of 2001, 2002, 2003, 2005 and 2016. Our results show that in 2001, 20% of the reef area presented low susceptibility to bleaching, while 80% presented medium susceptibility. 2002 was the year with the lowest susceptibility, being very low in 18% of the area and low in 82%. In 2003, 75% of the area showed low susceptibility and 25% medium. In 2005, the area of medium susceptibility reached 90%, while 10% presented low susceptibility. In 2016, 19% of the area presented medium and 81% high susceptibility. The year 2016 showed the highest susceptibility between the years studied, suggesting a higher percentage of bleached colonies, which is corroborated by the fact that this year was considered by NASA and NOAA as the warmest year since 1880. The results also show that the bleaching pattern is spatially differentiated. The reefs from the coastal arch of Abrolhos present the greater susceptibility to bleaching. Exception is made to Timbebas reefs that, although located in the coastal arch, are more similar to the outer arch reefs that are less susceptible to the bleaching