Evento de blanqueamiento masivo en la zona norte del Gofo Pérsico, 2012

Coral bleaching events due to elevated temperatures are increasing in both frequency and magnitude worldwide. Mass bleaching was recorded at five sites in the northern Persian Gulf during August and September 2012. Based on available seawater temperature data from field, satellite and previous studies, we suggest that the coral bleaching threshold temperature in the northern Persian Gulf is between 33.5 and 34°C, which is about 1.5 to 2.5°C lower than that in the southern part. To assess the bleaching effects, coral genera counted during 60-minute dives were categorized into four groups including healthy, slightly bleached ( 50% bleached tissue) and fully bleached colonies. The anomalously high sea surface temperature resulted in massive coral bleaching (~84% coral colonies affected). Acropora spp. colonies, which are known as the most vulnerable corals to thermal stress, were less affected by the bleaching than massive corals, such as Porites, which are among the most thermo-tolerant corals. Turbid waters, suggested as coral refugia against global warming, did not protect corals in this study since most affected corals were found in the most turbid waters. The 2012 bleaching in the northern Persian Gulf was relatively strong from the viewpoint of coral bleaching severity. Long-term monitoring is needed to understand the actual consequences of the bleaching event on the coral reefs and communities.Los eventos de blanqueamiento de corales están aumentando en frecuencia y magnitud debido al aumento de la temperatura en los océanos. En este trabajo se describe un evento de blanqueamiento masivo observado en seis localidades del norte del Golfo Pérsico entre Agosto y Septiembre de 2012. Los datos de temperatura disponibles, medidas in situ y observaciones de satélites de la temperatura de la superficie del mar, sugieren que la temperatura umbral que desencadena el blanqueo de coral en el norte del Golfo Pérsico corresponde a una temperatura de entre 33,5-34°C que es una temperatura entre 1.5 a 2.5°C inferior a la observada en las zonas más meridionales del Golfo Persico (35-36°C). Para la evaluación de los efectos de blanqueo sobre las comunidades de coral, se realizaron transectos de 60 minutos entre 0 y 6 m de profundidad. Durante las inmersiones cada colonia de coral se identificó a nivel de género y su estado se asignó a una de las siguientes categorías: no afectada, ligeramente afectada ( 50% del tejido blanqueado) y colonias totalmente afectadas (100% del tejido blanqueado). El análisis de los datos de temperatura permitió identificar una anomalía térmica durante el periodo de blanqueamiento que afectó a un 84% de las colonias censadas. Contrariamente a otros eventos de blanqueamiento analizados, las colonias de Acropora spp., que se encuentran entre las especies más vulnerables al estrés térmico, fueron menos afectadas que las especies de corales masivos como Porites spp. que normalmente presentan una gran resistencia al estrés térmico. Igualmente a pesar que la turbidez de las aguas ha sido señalada como un factor protector en el contexto del calentamiento global, en nuestro estudio observamos que las zonas más afectadas por el blanqueamiento presentaban las tasas de turbidez más elevadas. En conclusión el evento de blanqueamiento de 2012 observado en el norte del Golfo Pérsico afectó severamente a las comunidades de coral. El seguimiento a largo plazo de las comunidades de coral se presenta como una necesidad para comprender las consecuencias de los eventos de blanqueamiento

Mass Mortality of Porites Corals on Northern Persian Gulf Reefs due to Sediment-Microbial Interactions

Little information is available on coral diseases in the Persian Gulf; however, in the recent years, reports of coral diseases increased in particular from Iranian side of the Persian Gulf. In this paper we report a White Mat Disease resulting in mass mortality of Porites colonies at Hormuz Island. This outbreak infected 96% of all Porites colonies and killed 58±30% (mean ± SD) of all Porites tissues

Conservation needs to evolve to survive in the post‐pandemic world

The conservation of biodiversity—and the vital ecosystem services it generates—is one of the greatest challenges humanity faces, yet the field faces drastic funding cuts as society realigns its priorities in the face of the COVID‐19 pandemic. Here, we argue that diverting attention from conservation would, however, increase the risk of further global health crises because the emergence of novel infectious diseases is partially driven by global environmental change. As the discrepancy between conservation needs and society's willingness to pay for them grows, conservation will have to evolve to stay relevant in the age global change‐induced human infectious disease

There is an inverse relationship between the capacity of climate change refugia and species adaptation potential

Climate change refugia and adaptation are two important mechanisms by which species may survive ongoing climate change (Moritz et al., 2013). However, how these two mechanisms interact is poorly understood. The goal of this paper is to explore their interaction, focusing specifically on ocean acidification refugia

Biological interactions: The overlooked aspects of marine climate change refugia

WOS:000477304300001International audienceThis article emphasizes on biological interactions as an important overlooked criterion to better assess the chance of target marine species in potential refugia to survive climate change. It proposes future climate change refugia studies must consider the reciprocal interactions among climate change, biological factor, and conservation strategies

Combined ocean acidification and low temperature stressors cause coral mortality

Oceans are predicted to become more acidic and experience more temperature variability-both hot and cold-as climate changes. Ocean acidification negatively impacts reef-building corals, especially when interacting with other stressors such as elevated temperature. However, the effects of combined acidification and low temperature stress have yet to be assessed. Here, we exposed nubbins of the scleractinian coral Montipora digitata to ecologically relevant acidic, cold, or combined stress for 2 weeks. Coral nubbins exhibited 100% survival in isolated acidic and cold treatments, but 30% mortality under combined conditions. These results provide further evidence that coupled stressors have an interactive effect on coral physiology, and reveal that corals in colder environments are also susceptible to the deleterious impacts of coupled ocean acidification and thermal stress

Corallivory and algal dynamics on some coral reefs in the Persian Gulf

Macroalgae are a sign of degradation of coral reefs. Distribution of macroalgae on reefs is moderated by grazers including fish and sea urchins. However, several fish species including certain parrotfishes graze on live coral tissues, at times causing profound damage. In this paper, the potential role of macroalgae in suppressing parrotfish predation on Porites corals, the dominant coral genus in Qeshm Island, is investigated at three research sites at Qeshm Island in the Persian Gulf between April and July 2014 and 2015. Macroalgae, which were abundant in April, decreased significantly in frequency in July, while at the same time, the percentage of Porites colonies, the frequency of fish bite marks on Porites colonies, and the overall area of live coral tissue, which was grazed by parrotfishes increased dramatically, all of which were only negligible in April (with certain exceptions). Nevertheless, no changes were observed in parrotfish abundance. Despite partially supportive statistical data, because of the observed exceptions, this phenomenon is more likely to be due to other factors, in particular the increased nutritional values of the corals in July in comparison to April. However, to understand the cause(s) and mechanisms involved in this annual phenomenon, more investigations seem necessary

Colony-specific investigations reveal highly variable responses among individual corals to ocean acidification and warming

As anthropogenic climate change is an ongoing concern, scientific investigations on its impacts on coral reefs are increasing. Although impacts of combined ocean acidification (OA) and temperature stress (T) on reef-building scleractinian corals have been studied at the genus, species and population levels, there are little data available on how individual corals respond to combined OA and anomalous temperatures. In this study, we exposed individual colonies of Acropora digitifera, Montipora digitata and Porites cylindrica to four pCO2-temperature treatments including 400 µatm-28 °C, 400 µatm-31 °C, 1000 µatm-28 °C and 1000 µatm-31 °C for 26 days. Physiological parameters including calcification, protein content, maximum photosynthetic efficiency, Symbiodinium density, and chlorophyll content along with Symbiodinium type of each colony were examined. Along with intercolonial responses, responses of individual colonies versus pooled data to the treatments were investigated. The main results were: 1) responses to either OA or T or their combination were different between individual colonies when considering physiological functions; 2) tolerance to either OA or T was not synonymous with tolerance to the other parameter; 3) tolerance to both OA and T did not necessarily lead to tolerance of OA and T combined (OAT) at the same time; 4) OAT had negative, positive or no impacts on physiological functions of coral colonies; and 5) pooled data were not representative of responses of all individual colonies. Indeed, the pooled data obscured actual responses of individual colonies or presented a response that was not observed in any individual. From the results of this study we recommend improving experimental designs of studies investigating physiological responses of corals to climate change by complementing them with colony-specific examinations