Visualization of oxygen distribution patterns caused by coral and algae.

Planar optodes were used to visualize oxygen distribution patterns associated with a coral reef associated green algae (Chaetomorpha sp.) and a hermatypic coral (Favia sp.) separately, as standalone organisms, and placed in close proximity mimicking coral-algal interactions. Oxygen patterns were assessed in light and dark conditions and under varying flow regimes. The images show discrete high oxygen concentration regions above the organisms during lighted periods and low oxygen in the dark. Size and orientation of these areas were dependent on flow regime. For corals and algae in close proximity the 2D optodes show areas of extremely low oxygen concentration at the interaction interfaces under both dark (18.4 ± 7.7 µmol O2 L(- 1)) and daylight (97.9 ± 27.5 µmol O2 L(- 1)) conditions. These images present the first two-dimensional visualization of oxygen gradients generated by benthic reef algae and corals under varying flow conditions and provide a 2D depiction of previously observed hypoxic zones at coral algae interfaces. This approach allows for visualization of locally confined, distinctive alterations of oxygen concentrations facilitated by benthic organisms and provides compelling evidence for hypoxic conditions at coral-algae interaction zones

Numerical simulation of stability and stability control of high speed compressible rotating couette flow

The nonlinear temporal evolution of disturbances in compressible flow between infinitely long, concentric cylinders is investigated through direct numerical simulations of the full, three-dimensional Navier-Stokes and energy equations. Counter-rotating cylinders separated by wide gaps are considered with supersonic velocities of the inner cylinder. Initially, the primary disturbance grows exponentially in accordance with linear stability theory. As the disturbances evolve, higher harmonics and subharmonics are generated in a cascading order eventually reaching a saturation state. Subsequent highly nonlinear stages of the evolution are governed by the interaction of the disturbance modes, particularly the axial subharmonics. Nonlinear evolution of the disturbance field is characterized by the formation of high-shear layers extending from the inner cylinder towards the center of the gap in the form of jets similar to the ejection events in transitional and turbulent wall-bounded shear flows

Influence of coral and algal exudates on microbially mediated reef metabolism.

Benthic primary producers in tropical reef ecosystems can alter biogeochemical cycling and microbial processes in the surrounding seawater. In order to quantify these influences, we measured rates of photosynthesis, respiration, and dissolved organic carbon (DOC) exudate release by the dominant benthic primary producers (calcifying and non-calcifying macroalgae, turf-algae and corals) on reefs of Mo'orea French Polynesia. Subsequently, we examined planktonic and benthic microbial community response to these dissolved exudates by measuring bacterial growth rates and oxygen and DOC fluxes in dark and daylight incubation experiments. All benthic primary producers exuded significant quantities of DOC (roughly 10% of their daily fixed carbon) into the surrounding water over a diurnal cycle. The microbial community responses were dependent upon the source of the exudates and whether the inoculum of microbes included planktonic or planktonic plus benthic communities. The planktonic and benthic microbial communities in the unamended control treatments exhibited opposing influences on DO concentration where respiration dominated in treatments comprised solely of plankton and autotrophy dominated in treatments with benthic plus plankon microbial communities. Coral exudates (and associated inorganic nutrients) caused a shift towards a net autotrophic microbial metabolism by increasing the net production of oxygen by the benthic and decreasing the net consumption of oxygen by the planktonic microbial community. In contrast, the addition of algal exudates decreased the net primary production by the benthic communities and increased the net consumption of oxygen by the planktonic microbial community thereby resulting in a shift towards net heterotrophic community metabolism. When scaled up to the reef habitat, exudate-induced effects on microbial respiration did not outweigh the high oxygen production rates of benthic algae, such that reef areas dominated with benthic primary producers were always estimated to be net autotrophic. However, estimates of microbial consumption of DOC at the reef scale surpassed the DOC exudation rates suggesting net consumption of DOC at the reef-scale. In situ mesocosm experiments using custom-made benthic chambers placed over different types of benthic communities exhibited identical trends to those found in incubation experiments. Here we provide the first comprehensive dataset examining direct primary producer-induced, and indirect microbially mediated alterations of elemental cycling in both benthic and planktonic reef environments over diurnal cycles. Our results highlight the variability of the influence of different benthic primary producers on microbial metabolism in reef ecosystems and the potential implications for energy transfer to higher trophic levels during shifts from coral to algal dominance on reefs

Hyperspectral and Physiological Analyses of Coral-Algal Interactions

Space limitation leads to competition between benthic, sessile organisms on coral reefs. As a primary example, reef-building corals are in direct contact with each other and many different species and functional groups of algae. Here we characterize interactions between three coral genera and three algal functional groups using a combination of hyperspectral imaging and oxygen microprofiling. We also performed in situ interaction transects to quantify the relative occurrence of these interaction on coral reefs. These studies were conducted in the Southern Line Islands, home to some of the most remote and near-pristine reefs in the world. Our goal was to determine if different types of coral-coral and coral-algal interactions were characterized by unique fine-scale physiological signatures. This is the first report using hyperspectral imaging for characterization of marine benthic organisms at the micron scale and proved to be a valuable tool for discriminating among different photosynthetic organisms. Consistent patterns emerged in physiology across different types of competitive interactions. In cases where corals were in direct contact with turf or macroalgae, there was a zone of hypoxia and altered pigmentation on the coral. In contrast, interaction zones between corals and crustose coralline algae (CCA) were not hypoxic and the coral tissue was consistent across the colony. Our results suggest that at least two main characteristic coral interaction phenotypes exist: 1) hypoxia and coral tissue disruption, seen with interactions between corals and some species of CCA. Hyperspectral imaging in combination with oxygen profiling provided useful information on competitive interactions between benthic reef organisms, and demonstrated that some turf and fleshy macroalgae can be constant source of stress for corals, while CCA are not

Analysis of building damage caused by earthquakes in Eastern Turkey

Od 23. listopada 2011. do danas u istočnoj Turskoj svjedočili smo brojnim podrhtavanjima tla različite jačine. Dvije takve pojave u gradovima Vanu i Ercişu odnijele su mnoge živote i uzrokovale veće materijalne štete. Više od 600.000 ljudi osjetilo je posljedice potresa u tom razdoblju. Van je jedna od najnovijih i najbrže izgrađenih pokrajina Turske, te je potrebno temeljito ispitati karakteristike građevina navedene regije u kontekstu potresa. U članku se analiziraju vrste oštećenja zgrada uslijed potresa te uzroci nastajanja oštećenja na različitim građevinama u Vanu i Ercişu.Numerous ground motions of various intensities have been registered in Eastern Turkey since 23 October 2011. Two of them resulted in severe loss of life and great material damage in the towns of Van and Erciş. More than 600,000 people were affected by damage caused by earthquakes in that period. Van is one of the most recent and fastest developing regions of Turkey, which is why thorough investigations must be made to check seismic properties of buildings erected in this region. Types of seismic damage inflicted on buildings, and causes of damage to various buildings built in Van and Erciş, are analysed in the paper

Histopathologic investigation of the protective effects of omega-3 fatty acids against boric acid-induced injury in kidney and testis tissue

Objective: In this study, it was aimed to evaluate the effects of boric acid on rat kidney and testis tissues histopathologically. Secondly, the protective effects of omega-3 fatty acid against boric acid-induced renal and testicular toxicity were investigated. Methods: 32 wistar albino rats were divided into 4 groups as follows: Control, Omega-3 (400 mg/kg/day for 10 days), Boric acid (375 mg/kg/day for 10 days) and Boric acid+omega-3 (both drugs same dosage for same day). Kidney and testis tissues were evaluated using a scoring system based on the extent of certain histopathological changes. Results: In histopathological examination, boric acid caused significant degeneration in both testis and kidney tissues. Most evident findings were glomerular shrinkage and necrosis, hemorrhage and tubular cell degeneration in kidneys, and exfoliation of seminiferous tubule cells, detachement of epithelium from basement membrane, decreased cellularity and degeneration in epithelial cells in testis tissues. Omega-3 administration significantly attenuated these changes. Conclusion: To our literature search, this is the first study reporting protective effects of omega-3 fatty acid against boric-acid-induced testicular and renal injury