What governs the presence of residual vegetation in boreal wildfires?

Wildfires are frequent boreal forest disturbances in Canada, and emulating their patterns with forest harvesting has emerged as a common forest management goal. Wildfires contain many patches of residual vegetation of various size, shape, and composition; understanding their characteristics provides insights for improved emulation criteria. We studied the occurrence of residual vegetation within eleven boreal wildfire events in a natural setting; fires ignited by lightning, no suppression efforts, and no prior anthropogenic disturbances. Relative importance of the measurable geo-environmental factors and their marginal effects on residual presence are studied using Random Forests. These factors included distance from natural firebreaks (wetland, bedrock and non-vegetated areas, and water), land cover, and topographic variables (elevation, slope, and ruggedness index). We present results at spatial resolutions ranging from four to 64 m while emphasizing four and 32 m since they mimic IKONOS- and Landsat-type images. Natural firebreak features, especially the proximity to wetlands, are among the most important variables that explain the likelihood residual occurrence. The majority of residual vegetation areas are concentrated within 100 m of wetlands. Topographic variables, typically important in rugged terrain, are less important in explaining the presence of residuals within our study fires.     

Weathering of ilmenite from Chavara deposit and its comparison with Manavalakurichi placer ilmenite,southwestern India

The magnetic fractions of ilmenite from the beach placer deposit of Chavara, southwest India have been studied for mineralogical and chemical composition to assess the range of their physical and chemical variations with weathering. Chavara deposit represents a highly weathered and relatively homogenous concentration. Significant variation in composition has been documented with alteration. The most magnetic of the fractions of ilmenite, separated at 0.15 Å, and with a susceptibility of 3.2 × 10^?6 m³ kg^?1, indicates the presence of haematite–ilmenite intergrowth. An iron-poor, titanium-rich component of the ilmenite ore has been identified from among the magnetic fractions of the Chavara ilmenite albeit with an undesirably high Nb₂O₅ (0.28%), Cr₂O₃ (0.23%) and Th (149 ppm) contents. The ilmenite from Chavara is compared with that from the nearby Manavalakurichi deposit of similar geological setting and provenance. The lower ferrous iron oxide (2.32–14.22%) and higher TiO₂ (56.31–66.45%) contents highlight the advanced state of alteration of Chavara. This is also evidenced by the relatively higher Fe³⁺/Fe²⁺ ratio compared to Manavalakurichi ilmenite. In fact, the ilmenite has significantly been converted to pseudorutile/leucoxene.     

Transposable genetic elements inSpirulina and potential applications for genetic engineering

Transposable elements in cyanobacteria are briefly reviewed. Evidence is presented to show that transposable elements inSpirulina platensis is actually reflected on the phenotype change, i e., helical to straight filaments. Transposition intermediates of DNA were isolated from the extrachromosome and the transposition was related to helical variations inSpirulina. Uses of transposable elements for microalgal recombination are discussed based on the transposition mechanism.

     

Breeding and mass scale rearing of clownfish Amphiprion percula: feeding and rearing in brackishwater

Breeding and mass scale larval rearing of clownfish Amphiprion percula is very limited in brackishwater. We designed an indoor program of A. percula culture in brackishwater with a salinity of 24±1, during which the impacts of feed type, water temperature, and light intensity, on the efficiency of its reproduction, were revealed. The fish were accommodated along with sea anemones in fibre glass tanks to determine the influence of brooder diet on breeding efficiency. Higher reproductive efficiency [number of eggs laid (276 22.3 eggs)] was observed when fish were fed live Acetes sp. rather than clam (204 16.4 eggs), trash fish (155 12 eggs) and formulated feed (110 10 eggs). The spawning rate was increased during September and October (water temperature, 28.74 0.55°C) on average of 2.4 spawning per month; and low spawning rate was in January (water temperature, 24.55 0.45°C) on average of 1 spawning per month. Among three light intensities (100, 500, and 900 lx) set to evaluate larval survival rate, larvae showed the highest survival rate (65.5%) at 900 lx. The breeding method specifically in brackishwater developed in the present study is a new approach, will help the people from the regions of estuary and backwater to enhance their livelihood and it will lead to reduce the exploitation from the wild habitat.     

Coral reef bleaching at Agatti Island of Lakshadweep atolls, India

A survey on coral bleaching was carried out at Agatti Island of Lakshadweep from May to June 2010.Elevated sea surface temperatures(SSTs)of the region exceeded the seasonal average and delayed the onset of monsoon,which triggered widespread bleaching of corals.The Agatti reefs showed an average of 73%bleached corals with apparent bleaching-related mortality of sea anemones(87%)and giant clams(83%).The SST increased up to 34℃with an average maximum SST of 32.5℃ during the study period between May and June 2010.Coral reefs on the southern side of the island are fully or partially exposed to sun light during low tide in contrast to the other side.This suggests that the mortality is more likely due to the low tide exposure than exclusively due to the elevated SST.Observations indicated a clear increase in coral bleaching during April 2010,at levels higher than that in normal summer.     

Differential Alteration of Ilmenite in a Tropical Beach Placer, Southern India: Microscopic and Electron Probe Evidences

Abstract. The study based on microscopic and microprobe techniques reveals that ilmenite of Manavalakurichi deposit has generally reached the alteration phase of 'leached ilmenite'. The XRD and bulk chemical analysis confirm the limited alteration undergone by ilmenite grains. Ilmenite alteration has been found to be a process of continuous leaching of iron from the mineral lattice and hydroxylisation. The enrichment of trace elements with progressive alteration is discussed. Si and Al are enriched by more than 100 fold. The prevalence of reducing environment at present in the deposit indicates that the oxidation of ferrous iron leading to pseudorutile formation would have occurred during transportation of sediments.     

Interannual variability of upwelling indices in the Southeastern Arabian Sea: A satellite based study

Increase in sea surface temperature with global warming has an impact on coastal upwelling. Past two decades (1988 to 2007) of satellite observed sea surface temperatures and space borne scatterometer measured winds have provided an insight into the dynamics of coastal upwelling in the southeastern Arabian Sea, in the global warming scenario. These high resolution data products have shown inconsistent variability with a rapid rise in sea surface temperature between 1992 and 1998 and again from 2004 to 2007. The upwelling indices derived from both sea surface temperature and wind have shown that there is an increase in the intensity of upwelling during the period 1998 to 2004 than the previous decade. These indices have been modulated by the extreme climatic events like El-Nino and Indian Ocean Dipole that happened during 1991–92 and 1997–98. A considerable drop in the intensity of upwelling was observed concurrent with these events. Apart from the impact of global warming on the upwelling, the present study also provides an insight into spatial variability of upwelling along the coast. Noticeable fact is that the intensity of offshore Ekman transport off 8°N during the winter monsoon is as high as that during the usual upwelling season in summer monsoon. A drop in the meridional wind speed during the years 2005, 2006 and 2007 has resulted in extreme decrease in upwelling though the zonal wind and the total wind magnitude are a notch higher than the previous years. This decrease in upwelling strength has resulted in reduced productivity too.     

Tsunami in the last 15 years: a bibliometric analysis with a detailed overview and future directions

In the last fifteen years, tsunami science has progressed at a rapid pace. Three major tsunamis: The Indian Ocean in 2004, the 2011 Tohoku tsunami, and the 2018 Palu tsunami were significant landmarks in the history of tsunami science. All the three tsunamis, as mentioned, suffered from either no warning or poor reception of the alerts issued. Various lessons learned, consequent numerical models proposed, post-2004 tsunami damage findings manifested into solutions. However, the misperceived solutions led to a disastrous impact of the 2011 Tohoku event. In the following years, numerous improvements in warning systems and community preparedness frameworks were proposed and implemented. The contributions and new findings have added multi-fold advancements to tsunami science progress. Later, the 2018 Palu tsunami happened and again led to a massive loss of life and property. The warning systems and community seemed un-prepared for this non-seismic tsunami. A significant change is to take place in tsunami science practices and solutions. The 2018 tsunami is one of the most discussed and researched events concerning the palaeotsunami records, damage assessment, and source findings. In the new era, using machine learning and deep learning prevails in all the fields related to tsunami science. This article presents a complete 15-year bibliometric analysis of tsunami research from Scopus and Web of Science (WoS). The review of majorly cited documents in the form of a progressing storyline has highlighted the need for multidisciplinary research to design and propose practical solutions.

     

Embryology of Maldives clownfish, Amphiprion nigripes (Amphiprioninae)

This study investigated the embryonic development of Maldives clownfish Amphiprion nigripes under natural conditions (28 - 30℃) at a lagoon of Agatti Island, Lakshadweep, India. The newly deposited fish egg was capsule-shaped and orange-red, with a (0.73 ± 0.04) mm3 yolk containing 5 - 10 fat globules. The embryonic development of fertilized eggs was divided into 26 stages and the time elapsing for each stage was recorded. Results showed that the cleavage was rapid, with the first division observed 1 h 20 min after fertilization. Blastulation occurred 4 h later, followed by gastrulation 12 h after fertilization, with a yolk volume of (0.61 ± 0.06) mm3. The organogenesis process started 22 h after fertilization when the blastopores closed and notochord formation began. The embryonic stage was recorded 24 h later, with the appearance of forebrain, midbrain, hindbrain, melanophores on yolk-sac and 22 somites, and a decreased yolk volume of (0.54 ± 0.08) mm3. Other organs developed well 31 h after fertilization, whereas the heart started beating and blood circulation began 78 h later. Red pigmentation (erytrophores) appeared 96 h after fertilization, with a small yolk volume of (0.22 ± 0.02) mm3. Mouth developed well and eyes were noticeable 120 h later, with head, pectoral fin and tail frequently moving 144 h after fertilization. The embryo reached the pre-hatching stage 168 h later and started to hatch after 170 - 180 h incubation. This study first detailed the embryonic development and yolk absorption of A. nigripes under natural conditions.