Effect of Nutrients on Diatom Growth: A Review

Diatoms are one of the unicellular algae with a rare presence of unaltered, durable, transparent and species-specific silica frustules that persist even after cell death in the deposits of water bodies. Diatom has high capacity for absorption of metals for maintaining the water quality and high rate of multiplication. These characters promoted the use of this microbial biomass for effluent detoxification. These diatoms can also solve metal toxicity problems in aquatic ecosystems in the water polluted environment. In the present review, the focus is on several nutrients (nitrogen, phosphorus, iron and silica) that are essential for the growth of diatoms at very low concentrations, but most of them are toxic at high concentrations. It also shows the relationship between heavy metal stress and lipid body induction which may be a valuable indicator for the evaluation of heavy metal contamination of fluvial ecosystems. HIGHLIGHTS Diatoms are eukaryotic, unicellular, photosynthetic, silica-containing microscopic algae with distinct geometric forms Diatoms are used for biomonitoring purposes for taxonomic and morphological properties of ecosystems, community and human disturbances Diatoms are also the primary producer of oil in the world responsible for fixing 25 % of CO2 and 30 % of crude oil diatoms Many diatoms are appropriate for lipid development up to 70 % of their body volume and are investigated for biofuel as a hotspot GRAPHICAL ABSTRACT

Crab-Eating Mongoose Herpestes urva: Occurrence and its Activity in Mid-Hills of Nepal

Small carnivores are able to adapt to patchy forests and human dominated landscape in proximity to water sources. Small carnivore’s population is declining due to anthropogenic effects, and in most of the areas, their occurrence is little known. We aimed to identify the spatial occurrence of crab-eating mongoose, the factors affecting the occurrence of species and coexistence with other species using camera trap. The crab-eating mongoose mostly preferred the shrub-land habitat (65%) and followed by agriculture land, forest and grassland. Almost all preferred habitats were near to water sources. The occurrence of crab-eating mongoose was influenced by human disturbances. Their occurrences were decreased with increasing disturbances. In addition, the crab-eating mongoose’s occurrence was also decreased with increasing distance to water sources. The movement activities of crab-eating mongoose were varied according to time period (F = 6; df = 14; p < 0.013), and was mostly active at day to mid-night (16.00 to 12.00 hours) and mid-night to early morning (12.00 to 8.00 hours). The crab-eating mongoose co-exists with other carnivores including Leopard, Jungle cat, Masked-palm civet, Small Indian mongoose, Leopard cat, Yellow-throated martin, and Large Indian civet. In addition, its occurrence was affected by human interference. The data available from this study can be used to develop site/species-specific conservation plans that aid stewardship for biodiversity conservation.

Anti-cancer Activity of Human Gastrointestinal Bacteria

Malignant neoplasm is one of the most incurable diseases among inflammatory diseases. Researchers have been studying for decades to win over this lethal disease and provide the light of hope to humankind. The gastrointestinal bacteria of human hold a complex ecosystem and maintain homeostasis. One hundred trillion microbes are residing in the gastrointestinal tract of human. Disturbances in the microbiota of human&rsquo;s gastrointestinal tract can create immune response against inflammation and also can develop diseases , including cancer. The bacteria of the gastrointestinal tract of human, can secrete a variety of metabolites and bioproducts which aid in the preservation of homeostasis in the host and gut. During pathogenic dysbiosis, on the other hand, numerous microbiota subpopulations may increase and create excessive levels of toxins, which can cause inflammation and cancer. Furthermore, the immune system of host and the epithelium cell can be influenced by gut microbiota. Probiotics, which are bacteria that live in the gut, have been protected against tumor formation. Probiotics are now studied to see if they can help fight dysbiosis in cancer patients undergoing chemotherapy or radiotherapy because of their capacity to maintain gut homeostasis. Countless numbers of gut bacteria have demonstrated anti-cancer efficiency in cancer treatment, prevention, and boosting the efficiency of immunotherapy. The review article has briefly explained the anti-cancer immunity of gut microbes and their application in treating a variety of cancer. This review paper also highlights the pre-clinical studies of probiotics against cancer and the completed and ongoing clinical trials on cancers with the two most common and highly effective probiotics Lactobacillus and Bacillus spp.

Gene Flow and Genetic Structure Reveal Reduced Diversity between Generations of a Tropical Tree, Manilkara multifida Penn., in Atlantic Forest Fragments

The Atlantic Forest remnants in southern Bahia, Brazil, contain large tree species that have suffered disturbances in recent decades. Anthropogenic activities have led to a decrease in the population of many tree species and a loss of alleles that can maintain the evolutionary fitness of their populations. This study assessed patterns of genetic diversity, spatial genetic structure, and genetic structure among Manilkara multifida Penn. populations, comparing the genetic parameters of adult and juvenile trees. In particular, we collected leaves from adults and juveniles of M. multifida in two protected areas, the Veracel Station (EVC) and the Una Biological Reserve (UBR), located in threatened Atlantic Forest fragments. We observed a substantial decay in genetic variability between generations in both areas i.e., adults’ HO values were higher (EVC = 0.720, UBR = 0.736) than juveniles’ (EVC = 0.463 and UBR = 0.560). Both juveniles and adults showed genetic structure between the two areas (θ = 0.017 for adults and θ = 0.109 for juveniles). Additionally, forest fragments indicated an unexpectedly short gene flow. Our results, therefore, highlight the pervasive effects of historical deforestation and other human disturbances on the genetic diversity of M. multifida populations within a key conservation region of the Atlantic Forest biodiversity hotspot.

Water level variation at a beaver pond significantly impacts net CO₂ uptake of a continental bog

The carbon (C) dynamics of northern peatlands are sensitive to hydrological changes owing to ecohydrological feedback. We quantified and evaluated the impact of water level variations in a beaver pond (BP) on the CO2 flux dynamics of an adjacent, raised Sphagnum – shrub-dominated bog in southern Canada. We applied the CoupModel to the Mer Bleue bog, where the hydrological, energy and CO2 fluxes have been measured continuously for over 20 years. The lateral flow from the bog to the BP was estimated by the hydraulic gradient between the peatland and the BP's water level and the vertical profile of peat hydraulic conductivity. The model outputs were compared with the measured hydrological components, CO2 flux and energy flux data (1998–2019). CoupModel was able to reproduce the measured data well. The simulation shows that variation in the BP water level (naturally occurring or due to management) influenced the bog net ecosystem exchange of CO2 (NEE). Over 1998–2004, the BP water level was 0.75 to 1.0 m lower than during 2017–2019. Simulated net CO2 uptake was 55 g C m−2 yr−1 lower during 1998–2004 compared to 2017–2019 when there was no BP disturbance, which was similar to the differences in measured NEE between those periods. Peatland annual NEE was well correlated with water table depth within the bog, and NEE also shows a linear relation with the water level at the BP, with a slope of −120 g CO2-C m−2 yr−1 m−1. The current modelling predicts the bog may switch from CO2 sink to source when the BP water levels drop lower than ~ 1.7 m below the peat surface at the eddy covariance tower, 250 m from the BP. This study highlights the importance of natural and human disturbances to adjacent water bodies in regulating net CO2 uptake function of northern peatlands.

Ecosystem dynamics after forest fire. Blideen Atlas case

Human disturbances affect the majority of terrestrial ecosystems. The radical changes in the behaviour of ecological systems, partial or total destruction of plant biomass, often with the death of fundamental entities. Of these disturbances, fires affect many terrestrial ecosystems, particularly forests, by changing their floristic composition, their structure and their functioning; the global average annual forest area burned is estimated at 65 million ha. The Mediterranean basin, a hotspot, annually loses between 0.5 and 1 million hectares of forest. In Algeria, the annual average of areas destroyed by fire is between 45,000 and 50,000 ha. Our work set out to study the changes in the plant coverage of the land one year after the passage of fire. We studied the effects at the floristic, ecological and dynamic level in a forest ecosystem located in the north of Algeria (Atlas Blideen). The phytoecological inventory of vegetation (74 surveys, 162 species) was carried out from subjective sampling. To highlight the different groupings in the study area, classical statistical treatments (factorial analysis of correspondences) were applied to the floristic and ecological data. The results of computer processing made it possible to individualize and classify four plant groups according to the degree of the fire. The qualitative and quantitative analysis of these groups shows a therophytization of the flora, due to the regression of the forest cover (disappearance of the phanerophytes) caused by the passage of fire, with a floral procession represented mainly by Asteraceae, Poaceae and Fabaceae and an index disturbance which greatly exceeds 50%. However, some tree and shrub taxa such as cork oak, holm oak and Pistacia lentiscus tree have the capacity to reappear by rejecting the calcined stumps.

Forest characteristics and population structure of a threatened palm tree Caryota obtusa in the karst forest ecosystem of Yunnan, China

Aims Caryota obtusa of Arecaceae is a fascinating palm tree native to southwestern China, India, Myanmar, Thailand, Laos, and Vietnam. It is an economically important and threatened species and appears as a canopy dominant in some karst areas in Yunnan. We aim to clarify the forest structure, species diversity, population status and regeneration dynamics of C. obtusa in the karst forest ecosystem of Yunnan, China. Methods We established 56 vegetation plots dominated by C. obtusa in 10 counties of southern Yunnan. As based on the plot data, we analyzed the community stratification, floristic composition, and C. obtusa’s population structure. We used questionnaires to interview local people and recorded the human activity history on C. obtusa-dominated forests. Important findings: C. obtusa palm forests were distributed on limestone mountain slopes and gullies. There were seven forest community types. The stratification of each community included arborous layer, shrub layer and understory. The communities had rich species composition. For all the plots as a whole of each community type, Shannon-Wiener diversity index of either woody or herbaceous species ranged from 2.1-3.8. The DBH-class frequency distribution of C. obtusa was a multimodal type. The regeneration was sporadic and depended on intermediate natural disturbances. In current population structure, number of C. obtusa trees with small DBHs was consisted mainly of the forest communities with no or a slight degree of human disturbances. Intensive human activities terribly hindered C. obtusa’s recruitment, followed by medium intensity of human activities.