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News Article | May 2, 2017
Site: www.eurekalert.org

Marine surveys estimating fish population density and diversity are crucial to our understanding of how human activities impact coral reef ecosystems and to our ability to make informed management plans for sustainability. KAUST researchers recently conducted the first baseline surveys of reefs in the southern Red Sea by comparing reefs off the coast of Saudi Arabia with those of Sudan1. "A major issue is that there is no established historical record for Red Sea ecosystems," said Dr. Darren Coker, who worked on the project with KAUST M.Sc. Alumnus Alexander Kattan and Professor Michael Berumen all of the University's Red Sea Research Center. "This means we can only hypothesize what the natural reef environment would have looked like before human interference through fishing began." Berumen's team systematically compared 14 Saudi reefs with 16 offshore reefs in Sudan. The reefs are around 200-300 Km apart and share almost identical environmental conditions in terms of sea temperature, climate and coral species. However, Saudi Arabia has a long-established history of fishing, while Sudan does not. "There is much more to the story than just the numbers of fish we see," said Berumen. "We collected and analyzed data between and within regions to look at fish abundance, biomass and community diversity across all the reefs surveyed." "To minimize potential bias, I conducted all the survey dives myself," said Kattan, who trained intensively to ensure he could correctly identify fish species and accurately estimate their size underwater. "A friend helped me practice in a pool by diving with different sizes and shapes of simulated fish on popsicle sticks! Because size estimates were converted into biomass, it was vital that I was able to gauge sizes correctly." The team found that the biomass of top predators in the Sudanese reefs was almost three times that of the Saudi reefs. The top predators were far rarer in Saudi Arabian waters, a phenomenon that the researchers attribute to fishing pressures. Furthermore, fish abundance was around 62 % higher in Sudan and biomass was 20 % higher. There was also slightly greater diversity on the Sudanese reefs. "This is the strongest evidence yet of the impact of fishing on Saudi Arabia's reefs," said Berumen. "While Saudi Arabia appears to have lost many larger fish, these species, including top predators, have not completely disappeared, so there is an opportunity to turn the situation around. Saudi's reefs could be restored to the condition of the almost pristine Sudanese reefs through careful management and protection, and they could one day thrive as eco-tourism sites."

Neave M.,Charles Darwin University | Neave M.,Woods Hole Oceanographic Institution | Neave M.,Red Sea Research Center | Luter H.,Charles Darwin University | And 4 more authors.
MicrobiologyOpen | Year: 2014

Microbial source tracking is an area of research in which multiple approaches are used to identify the sources of elevated bacterial concentrations in recreational lakes and beaches. At our study location in Darwin, northern Australia, water quality in the harbor is generally good, however dry-season beach closures due to elevated Escherichia coli and enterococci counts are a cause for concern. The sources of these high bacteria counts are currently unknown. To address this, we sampled sewage outfalls, other potential inputs, such as urban rivers and drains, and surrounding beaches, and used genetic fingerprints from E. coli and enterococci communities, fecal markers and 454 pyrosequencing to track contamination sources. A sewage effluent outfall (Larrakeyah discharge) was a source of bacteria, including fecal bacteria that impacted nearby beaches. Two other treated effluent discharges did not appear to influence sites other than those directly adjacent. Several beaches contained fecal indicator bacteria that likely originated from urban rivers and creeks within the catchment. Generally, connectivity between the sites was observed within distinct geographical locations and it appeared that most of the bacterial contamination on Darwin beaches was confined to local sources. © 2014 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

News Article | February 15, 2017
Site: www.eurekalert.org

The close association between corals and bacteria may help protect coral from heat stress and bleaching Bacteria in certain microbiomes appear to help corals adapt to higher water temperatures and protect against bleaching, as shown by a KAUST-led research team1. Coral animals rely on algal and bacterial symbionts, known as their microbiome, to function and thrive. These mutually beneficial relationships could prove vital if corals are to survive the rapid warming of the oceans because short-lived bacteria can adapt more quickly than long-lived corals and thus may offer corals some protection. "Our challenge is to untangle and understand the symbiotic interactions between corals and other organisms," said Associate Professor of Marine Science Christian Voolstra at the Red Sea Research Center in KAUST, who led the project in collaboration with scientists at Stanford University. "We designed an experiment that allowed us to monitor coral-bacterial interactions over time and assess their responses to changes in water temperature." The team conducted their research in South Pacific reef pools off of Ofu Island in the National Park of American Samoa. They chose two pools in close proximity that hosted the same coral species, Acroporahyacinthus, but that had different naturally occurring water temperatures: one pool had a lower temperature range, rarely exceeding 32 degrees Celsius, while the other fluctuated between 25 and 35 degrees Celsius. The international team transplanted some coral fragments from one pool to the other and closely monitored them and their associated bacteria in both their native and new environments. "Seventeen months after transplantation, we conducted a short-term heat-stress experiment and found that the corals transplanted from the colder to the warmer environment had changed their associated bacteria and were more heat resistant," explained Voolstra. "Their microbiome was similar to the corals native to the warmer pool. This suggests that bacterial associations are flexible and can potentially help corals adapt to changing environments--an exciting outcome!" In the stress experiment, corals native to the cooler pool bleached significantly, while corals moved to the warmer pool 17 months earlier bleached less, in line with their newly acquired microbiome. Further analysis of the distinct microbial communities in the pools showed that the higher-temperature microbiomes had a higher-carbohydrate metabolism and a more functional sugar-transport system. "Our next step is to prove that specific bacteria directly contribute to the thermal tolerance of the host," said Voolstra. "We can do this by showing that the absence of a bacterium renders the coral host heat sensitive, whereas an association with the same bacterium makes coral more heat tolerant." "This is challenging because finding the right bacteria is like finding a needle in a haystack, but we'll go for it," said Voolstra.

News Article | February 19, 2017
Site: www.eurekalert.org

Advances in genomic research are helping scientists to reveal how corals and algae cooperate to combat environmental stresses. KAUST researchers have sequenced and compared the genomes of three strains of Symbiodinium, a member of the dinoflagellate algae family, to show their genomes have several features that promote a prosperous symbiotic relationship with corals1. Dinoflagellates are among the most prolific organisms on the planet, forming the basis of the oceanic food chain, and their close symbiotic relationships with corals help maintain healthy reefs. However, because dinoflagellates have unusually large genomes, very few species have been sequenced, leaving the exact nature of their symbiosis with corals elusive. "We had access to two Symbiodinium genomes, S.minutum and S.kawagutii, and we decided to sequence a third, S. microadriaticum," said Assistant Professor of Marine Science Manuel Aranda at the University's Red Sea Research Center, who led the project with his Center colleague Associate Professor of Marine Science Christian Voolstra and colleagues from the University's Computational Bioscience Research Center and Environmental Epigenetics Program. "This allowed us to compare the three genomes for common and disparate features and functions and hopefully to show how the species evolved to become symbionts to specific corals." The unusual makeup of the three Symbiodinium genomes meant that the team had to adjust their software to read the genomes correctly. Ultimately, their research revealed that Symbiodinium has evolved a rich array of bicarbonate and ammonium transporters. These proteins are used to harvest two important nutrients involved in coral-dinoflagellate symbiosis: carbon, which is needed for photosynthesis, and nitrogen, which is essential for growth and proliferation. Symbiodinium either evolved these transporters in response to symbiosis or the presence of these transporters allowed Symbiodinium to become a symbiont in the first place, noted Aranda.

Jessen C.,Leibniz Center for Tropical Marine Ecology | Villa Lizcano J.F.,Red Sea Research Center | Bayer T.,Red Sea Research Center | Roder C.,Red Sea Research Center | And 4 more authors.
PLoS ONE | Year: 2013

Coral reefs of the Central Red Sea display a high degree of endemism, and are increasingly threatened by anthropogenic effects due to intense local coastal development measures. Overfishing and eutrophication are among the most significant local pressures on these reefs, but there is no information available about their potential effects on the associated microbial community. Therefore, we compared holobiont physiology and 16S-based bacterial communities of tissue and mucus of the hard coral Acropora hemprichii after 1 and 16 weeks of in-situ inorganic nutrient enrichment (via fertilizer diffusion) and/or herbivore exclusion (via caging) in an offshore reef of the Central Red Sea. Simulated eutrophication and/or overfishing treatments did not affect coral physiology with respect to coral respiration rates, chlorophyll a content, zooxanthellae abundance, or δ 15N isotopic signatures. The bacterial community of A. hemprichii was rich and uneven, and diversity increased over time in all treatments. While distinct bacterial species were identified as a consequence of eutrophication, overfishing, or both, two bacterial species that could be classified to the genus Endozoicomonas were consistently abundant and constituted two thirds of bacteria in the coral. Several nitrogen-fixing and denitrifying bacteria were found in the coral specimens that were exposed to experimentally increased nutrients. However, no particular bacterial species was consistently associated with the coral under a given treatment and the single effects of manipulated eutrophication and overfishing could not predict the combined effect. Our data underlines the importance of conducting field studies in a holobiont framework, taking both, physiological and molecular measures into account. © 2013 Jessen et al.

Papadopoulos V.P.,Hellenic Center for Marine Research | Abualnaja Y.,Red Sea Research Center | Josey S.A.,UK National Oceanography Center | Bower A.,Woods Hole Oceanographic Institution | And 3 more authors.
Journal of Climate | Year: 2013

The influence of the atmospheric circulation on the winter air-sea heat fluxes over the northern Red Sea is investigated during the period 1985-2011. The analysis based on daily heat flux values reveals that most of the net surface heat exchange variability depends on the behavior of the turbulent components of the surface flux (the sum of the latent and sensible heat).The large-scale composite sea level pressure (SLP) maps corresponding to turbulent flux minima and maxima show distinct atmospheric circulation patterns associated with each case. In general, extreme heat loss (with turbulent flux lower than -400 W m-2) over the northern Red Sea is observed when anticyclonic conditions prevail over an area extending from the Mediterranean Sea to eastern Asia along with a recession of the equatorial African lowssystem. Subcenters of high pressure associated with this pattern generatethe required steep SLP gradient that enhances the wind magnitude and transfers cold and dry air masses from higher latitudes. Conversely, turbulent fluxmaxima (heat loss minimization with values from -100 to -50 W m-2) are associated with prevailing low pressures over the eastern Mediterranean andan extended equatorial African low that reaches the southern part of the Red Sea. In this case, a smooth SLP field over the northern Red Sea results in weak winds over the area that in turn reduce the surface heat loss. At the same time, southerlies blowing along the main axis of the Red Sea transfer warm and humid air northward, favoring heat flux maxima. © 2013 American Meteorological Society.

Moreno-Ostos E.,University of Malaga | Blanco J.M.,University of Malaga | Agusti S.,CSIC - Mediterranean Institute for Advanced Studies | Agusti S.,Red Sea Research Center | And 5 more authors.
Journal of Marine Systems | Year: 2015

Modelling the size-abundance spectrum of phytoplankton has proven to be a very useful tool for the analysis of physical-biological coupling and the vertical flux of carbon in oceanic ecosystems at different scales. A frequent observation relates high phytoplankton biovolume in productive regions with flatter spectrum slope and the opposite in oligotrophic ecosystems. Rather than this, the relationship between high biovolume phytoplankton assemblages and flatter size-abundance spectra does not correspond with measurements of the phytoplankton community in the Atlantic Ocean open waters. As part of the Malaspina Circunnavegation Expedition, sixty seven sampling stations within the Atlantic Ocean covering six oceanographic provinces, at different seasons, produced a complete set of phytoplankton size-spectra whose slope and biovolume did not show any obvious interrelation. In these oligotrophic sites, small (procaryotes) and medium-size (nanoplankton) cells are responsible for the most part of biovolume, and their response to environmental conditions does not apply to changes in the size-abundance spectrum slope as expected in richer, large-cell dominated ecosystems. © 2015 Elsevier B.V.

News Article | November 30, 2016
Site: www.eurekalert.org

The Association for the Sciences of Limnology and Oceanography recently elected Carlos Duarte, Director of the Red Sea Research Center and the Tarek Ahmed Juffali Research Chair in Red Sea Ecology in the University's Biological and Environmental Science and Engineering (BESE) division, an ASLO Fellow based on the sustained excellence of his contributions to ASLO and the aquatic sciences. The Fellows program was initiated in 2015 to honor ASLO members who have advanced the aquatic sciences via their exceptional contributions to the benefit of the society and its publications, meetings and other activities. The 2016 Fellows will be honored at the ASLO Meeting in Honolulu, in February 2017. "I have served as president-elect (elected), and the only non-American president thus far in the 80 year history of the society. I have also served as Member-at-Large (elected), as co-chair of one of the largest meetings thus far, as a member of various committees, as an associate editor of their main publication and I rank amongst the most published authors in that journal. I have also been recognized in the past with ASLO's Evelyn G. Hutchinson medal for scientific excellence. This level of service was thought to be worthy of my election as Sustaining Fellow," said Duarte. Duarte recognized the role KAUST has played in helping to support this election, "Joining KAUST has certainly helped me raise the level of my research and my capacity to collaborate with others," he said. He describes his latest research as focusing on the use of coastal ecosystems in support of climate change mitigation and adaptation and in exploring the functions and applications of the large pool of genes ocean microbes have evolved. "Going forward, I would like to use the fundamental research I do as a platform to develop ocean-based solutions to the grand challenges humanity faces. I aspire to contribute to making an intelligent use of the oceans a key milestone of the 21st century," he added. More information about the ASLO (formerly known as the American Society of Limnology and Oceanography) and the Fellows program, can be found at: http://aslo. . Carlos Duarte is the Director of the Red Sea Research Center and the Tarek Ahmed Juffali Research Chair in Red Sea Ecology in the University's Biological and Environmental Science and Engineering (BESE) division. His research focuses on understanding the impacts of global change in marine ecosystems, and addressing all components from microbes to megafauna. His research is poised at the interface between Earth and sustainability science, and is increasingly comprised of interdisciplinary components.

Klatt J.M.,Max Planck Institute for Marine Microbiology | Al-Najjar M.A.A.,Max Planck Institute for Marine Microbiology | Al-Najjar M.A.A.,Red Sea Research Center | Yilmaz P.,Max Planck Institute for Marine Microbiology | And 4 more authors.
Applied and Environmental Microbiology | Year: 2015

Before the Earth's complete oxygenation (0.58 to 0.55 billion years [Ga] ago), the photic zone of the Proterozoic oceans was probably redox stratified, with a slightly aerobic, nutrient-limited upper layer above a light-limited layer that tended toward euxinia. In such oceans, cyanobacteria capable of both oxygenic and sulfide-driven anoxygenic photosynthesis played a fundamental role in the global carbon, oxygen, and sulfur cycle. We have isolated a cyanobacterium, Pseudanabaena strain FS39, in which this versatility is still conserved, and we show that the transition between the two photosynthetic modes follows a surprisingly simple kinetic regulation controlled by this organism's affinity for H2S. Specifically, oxygenic photosynthesis is performed in addition to anoxygenic photosynthesis only when H2S becomes limiting and its concentration decreases below a threshold that increases predictably with the available ambient light. The carbon-based growth rates during oxygenic and anoxygenic photosynthesis were similar. However, Pseudanabaena FS39 additionally assimilated NO3 - during anoxygenic photosynthesis. Thus, the transition between anoxygenic and oxygenic photosynthesis was accompanied by a shift of the C/N ratio of the total bulk biomass. These mechanisms offer new insights into the way in which, despite nutrient limitation in the oxic photic zone in the mid-Proterozoic oceans, versatile cyanobacteria might have promoted oxygenic photosynthesis and total primary productivity, a key step that enabled the complete oxygenation of our planet and the subsequent diversification of life. © 2015, American Society for Microbiology.

Voolstra C.R.,Red Sea Research Center
Molecular Ecology | Year: 2013

The existence of coral reef ecosystems relies critically on the mutualistic relationship between calcifying cnidarians and photosynthetic, dinoflagellate endosymbionts in the genus Symbiodinium. Reef-corals have declined globally due to anthropogenic stressors, for example, rising sea-surface temperatures and pollution that often disrupt these symbiotic relationships (known as coral bleaching), exacerbating mass mortality and the spread of disease. This threatens one of the most biodiverse marine ecosystems providing habitats to millions of species and supporting an estimated 500 million people globally (Hoegh-Guldberg et al. 2007). Our understanding of cnidarian-dinoflagellate symbioses has improved notably with the recent application of genomic and transcriptomic tools (e.g. Voolstra et al. 2009; Bayer et al. 2012; Davy et al. 2012), but a model system that allows for easy manipulation in a laboratory environment is needed to decipher underlying cellular mechanisms important to the functioning of these symbioses. To this end, the sea anemone Aiptasia, otherwise known as a 'pest' to aquarium hobbyists, is emerging as such a model system (Schoenberg & Trench 1980; Sunagawa et al. 2009; Lehnert et al. 2012). Aiptasia is easy to grow in culture and, in contrast to its stony relatives, can be maintained aposymbiotically (i.e. dinoflagellate free) with regular feeding. However, we lack basic information on the natural distribution and genetic diversity of these anemones and their endosymbiotic dinoflagellates. These data are essential for placing the significance of this model system into an ecological context. In this issue of Molecular Ecology, Thornhill et al. (2013) are the first to present genetic evidence on the global distribution, diversity and population structure of Aiptasia and its associated Symbiodinium spp. By integrating analyses of the host and symbiont, this research concludes that the current Aitpasia taxonomy probably needs revision and that two distinct Aiptasia lineages are prevalent that have probably been spread through human activity. One lineage engages in a specific symbiosis with Symbiodinium minutum throughout the tropics, whereas a second, local Aiptasia sp. population in Florida appears more flexible in partnering with more than one symbiont. The existence of symbiont-specific and symbiont-flexible Aiptasia lineages can greatly complement laboratory-based experiments looking into mechanisms of symbiont selectivity. In a broader context, the study by Thornhill et al. (2013) should inspire more studies to target the natural environment of model systems in a global context targeting all participating member species when establishing ecological and genetic baselines. © 2013 John Wiley & Sons Ltd.

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