Heavy Summer Rains Research Articles

Enhancement of Waterlogging Tolerance and Improvement of Grain Quality in Waxy Maize With Exogenous EDAH: A Mixture of Ethephon and Diethyl Aminoethyl Hexanoate

ABSTRACTGlobal warming has led to more frequent extreme weather events, such as heavy summer rains, in the Huang‐Huai‐Hai region. These events significantly impede the growth and development of waxy maize in the area and disrupt the stable progression of the industry. However, there is a lack of effective agricultural measures to mitigate the impact of waterlogging, and the underlying regulation mechanisms remain unclear. To fill this knowledge gap, we conducted a two‐year experiment to assess whether exogenous EDAH (a mixture of ethephon and diethyl aminoethyl hexanoate (DA‐6), ethephon: DA‐6 = 27%: 3%) application during the waxy maize V6 stage, combined with 10 days of waterlogging treatment at the V6, VT and R2 growth stages. The results indicate that exogenous EDAH mitigates the adverse effects of waterlogging stress to a certain extent. It is noteworthy that exogenous EDAH increases the leaf area index and photosynthetic parameters of waxy maize, enhances the activity of catalase in ear leaves at the R3 stage, inhibits the accumulation of malondialdehyde and delays premature aging of plants. Furthermore, exogenous EDAH delays premature ripening of grains caused by waterlogging, increases the moisture content of fresh waxy maize grains during the fresh edible period, but does not effectively mitigate the yield losses caused by waterlogging. However, exogenous EDAH effectively improves grain quality under waterlogging stress, increasing the soluble sugar content and total protein content while reducing starch content, ultimately enhancing the edibility of fresh ears. Through TOPSIS comprehensive evaluation, it can be inferred that exogenous EDAH effectively mitigates the overall impact of waterlogging on waxy maize at both the V6 and VT stages. This research sheds light on potential strategies to mitigate the adverse effects of waterlogging on agricultural productivity and grain quality.

Evaluation on leachability of heavy metals from tailings: risk factor identification and cumulative influence

The leachability of heavy metals (HMs) in tailings is significantly affected by multivariate factors associated with environmental conditions. However, the leaching patterns of HMs in molybdenum (Mo) tailings due to environmental change and cumulative influences of multi-leaching factors remain unclear. The leaching behaviors of HMs in Mo tailings were studied through static leaching tests. The key leaching factors were discussed via simulating acid rain leaching scenario in terms of global and local environmental conditions. The potential risk factors were identified, and their cumulative influences on the leachability of HMs were evaluated with boosted regression trees (BRT) and generalized additive model (GAM) analyses. Environmental factors showed interactive effects on the leachability of HMs in tailings. The leachability of HMs in tailings decreased significantly with the interaction of increasing liquid/solid (L/S) ratio and pH. Rebound of leachability was observed with high L/S ratio (> 60) and long-time leaching (> 30h). L/S ratio and pH were the most sensitive factors to the leachability of HMs with the corresponding contribution of 40.8% and 27.1%, respectively, followed by leaching time and temperature (~ 16%). The total contribution of global climate-associated factors, i.e., L/S ratio, leaching time, and temperature to the leachability of HMs was up to 70%, while leachate pH shared the other 30%. With the increase of persistent heavy rain in summer globally, As and Cd were found to having higher leaching risks than the other HMs in tailings, although an obvious decrease in their leachability was obtained due to the improvement of acid rain pollution in China. The study provides a valuable method for the identification of potential risk factors and their associations with the leaching behaviors of HMs in tailings under the background of obvious improvement on acid rain pollution in China and global climate change.

Evaluating the effects of temperature on soil hydraulic and mechanical properties in the collapsing gully areas of south China

The soil hydrologic and mechanical properties play an important role in the slope stability in the red soil hilly region of southern China. In this study, the red soil layers in a collapsing gully wall were used to investigate the effects of temperature on the soil water retention curve (SWRC) and shear strength. The results showed that the SWRCs of the red soil under different temperatures could be accurately described by the van Genuchten (VG) model (R2 > 0.95, root mean square error (RMSE) < 0.024). An increasing temperature significantly decreased the soil water holding capacity (WHC), especially in the intermediate range of the SWRCs of the red soil. The soil saturated hydraulic conductivity (Ks) increased linearly with temperature. The soil cohesion and soil friction angle decreased by approximately 44.13% and 30.40% respectively when the soil water content increased from 0.24 cm3 cm−3 to 0.42 cm3 cm−3. The mean soil cohesion and soil friction angle decreased approximately 8.56 kPa and 1.34° respectively when the soil temperature increased from 25 °C to 40 °C. Regression analysis showed that the soil cohesion increased as the power function with increasing matric suction (0–2000 kPa), and friction angle increased as the linear function with increasing matric suction. These results illustrated that an increase in temperature will decrease soil matric suction and shear strength but enhance the soil infiltration rate under certain soil moisture levels. Therefore, the stability of a collapsing gully wall will sharply decrease under the conditions of high temperature and heavy rain in summer.

Physiological and Transcriptomic Analysis Reveals the Responses and Difference to High Temperature and Humidity Stress in Two Melon Genotypes.

Due to the frequent occurrence of continuous high temperatures and heavy rain in summer, extremely high-temperature and high-humidity environments occur, which seriously harms crop growth. High temperature and humidity (HTH) stress have become the main environmental factors of combined stress in summer. The responses of morphological indexes, physiological and biochemical indexes, gas exchange parameters, and chlorophyll fluorescence parameters were measured and combined with chloroplast ultrastructure and transcriptome sequencing to analyze the reasons for the difference in tolerance to HTH stress in HTH-sensitive ‘JIN TAI LANG’ and HTH-tolerant ‘JIN DI’ varieties. The results showed that with the extension of stress time, the superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX) activities of the two melon varieties increased rapidly, the leaf water content increased, and the tolerant varieties showed stronger antioxidant capacity. Among the sensitive cultivars, Pn, Fv/Fm, photosystem II, and photosystem I chlorophyll fluorescence parameters were severely inhibited and decreased rapidly with the extension of stress time, while the HTH-tolerant cultivars slightly decreased. The cell membrane and chloroplast damage in sensitive cultivars were more severe, and Lhca1, Lhca3, and Lhca4 proteins in photosystem II and Lhcb1-Lhcb6 proteins in photosystem I were inhibited compared with those in the tolerant cultivar. These conclusions may be the main reason for the different tolerances of the two cultivars. These findings will provide new insights into the response of other crops to HTH stress and also provide a basis for future research on the mechanism of HTH resistance in melon.

Crustal response to heavy rains in Southwest Japan 2017-2020

Weather fronts stationary above Southwest Japan often bring disastrous heavy rains in early summer. Here we study four such episodes in each of four summers between 2017 and 2020, and investigate transient lithospheric subsidence caused by rainwater loads using the daily coordinates of a dense network of continuous GNSS stations. After applying a network filter to remove common mode errors, we isolated subsidence signals of 1-2 centimeters in flooded regions. Such subsidence recovered mostly in a day as rainwater drained rapidly to nearby ocean promoted by large topographic slopes. Spatiotemporal correlation between subsidence and precipitation was weak due possibly to rapid post-precipitation migration of rainwater. However, a strong correlation was found between subsidence and rain spatially integrated over the entire Southwest Japan, i.e., bulk subsidence of ∼0.1 km3 (equivalent to the uniform subsidence ∼0.6 mm) occurred for every 1 Gt rainwater per day. This linearity breaks down for rains exceeding ∼10 Gt/day as rainwater possibly exceeds the water-holding capacity of forest catchments.

Overnight formation of a bouldery alluvial fan by a torrential rain in a granitic mountain (M. Seoraksan, Republic of Korea)

Mt. Seoraksan, Korea, is a rugged granitic mountain where extremely steep slopes and strongly seasonal rainfall have facilitated bedrock exposure and geomorphic changes mainly by rockfalls and streamflows. Although the environment was not suitable for alluvial fan formation, a bouldery alluvial fan, 170 m long and 330 m wide, formed overnight by a heavy summer rain in 2006. The fan consists of several meter-high boulder mounds and gently undulating cobble bars/sheets that are arranged in a fluvial longitudinal bar-like pattern. They are interpreted to have formed by highly competent and turbulent sheetfloods, which temporarily had the properties of hyperconcentrated flood flows. Formation of the whole alluvial fan by a single, casual hydro-meteorological event is inferred to have been possible because a threshold condition was reached in the source area. A rainfall event, which would have had no extreme effects before reaching the threshold, could probably trigger massive remobilization of bouldery sediments on the valley floors. The Seoraksan alluvial fan thus demonstrates the role of a geomorphic threshold in causing drastic changes in the hydrologic performance of the watershed. The morphology and sedimentology of the Seoraksan alluvial fan suggest that the fan is a modern example of a sheetflood-dominated alluvial fan, which has largely been ignored in spite of their potential diversity and abundance in glacial to periglacial, tropical, and temperate environments.

ВОЗМОЖНОСТЬ ИСПОЛЬЗОВАНИЯ АНСАМБЛЕВОГО МУЛЬТИМОДЕЛЬНОГО ПРОГНОЗА СИЛЬНЫХ ОСАДКОВ ДЛЯ ТЕРРИТОРИИ ПЕРМСКОГО КРАЯ НА ПРИМЕРЕ ЛЕТА 2019 Г

The multimodel ensemble technique for predicting heavy rain ( 15 mm/12 hours) in the Perm region with a lead time of 15 and 27 hours is analyzed. The quality of precipitation forecasts from GFS, GEM, ICON global hydrodynamic models and from the WRF-ARW model with 3 and 9-km grid spacing is assessed. For the summer of 2019, the GEM was found to provide the highest quality of heavy rain forecasts. The averaging over the ensemble of global models causes a sharp decrease in the number of false alarms and in the probability of detection. The scheme of global models combination consisting in the filtration of the GEM heavy rain forecasts and in the averaging of GFS, GEM, and ICON forecasts at the remaining points is developed. Application of the proposed scheme increases the reliability of short-range forecasts of heavy frontal rains in summer in the Perm region as compared to any separate model.

GEOTECHNICAL ACCIDENTS OF ROAD STRUTURES AND THEIR LICVIDATION

Geotechnical accidents often occur during road operation. To eliminate their consequences, various measures are required, taking into account the geological features of the site. Three cases of geotechnical accidents of road structures are considered: landslide damage to the bridge cone and the slope of the road embankment; the formation of a local landslide, plastic deformation and loss of stability of the roadbed, settlement of the culvert links; suffusion from the side of the railway cut under the cone of the bridge structure due to damage to the anti-filtration clay screen. In the first case, the reasons for the intensification of the landslide were periodic rises in the level of groundwater, the presence of areas not protected by vegetation, and areas of loose soil. The accident was eliminated by installing an anti-landslide structure made of bored piles, embedded with their lower ends into rocky ground. In the second case, the reasons were waterlogging due to heavy summer rains and melting snow next spring. To eliminate the accident, drainage was arranged in the adjacent territory; the soil was partially replaced, reinforcement with geotextiles was carried out, slopes with a berm were laid, the base of the subgrade was strengthened. In the third case, the removal of soil particles (suffusion) from the side of the railway excavation under the cone of the bridge structure occurred due to damage to the anti-filtration clay screen during the creation of the construction site. After the restoration of the screen and the drainage device, the suffusion was eliminated. The above examples show the importance of engineering and geological substantiation in the design of transport construction facilities.

Nitrogen benefits of ten legume pre-crops for wheat assessed by field measurements and modelling

Abstract The positive effect of grain legume pre-crops on the yield of the subsequent crop has been studied widely, whereas less information is available on the nitrogen (N) processes related to this positive effect, especially for a wide range of grain legume species. The objective was to quantify and understand the effect of grain legume compared to cereal pre-crops (sown in 2014 and 2016) on grain and shoot N yields and shoot N concentration of wheat (Triticum aestivum) grown the following year (2015 and 2017). Spring legumes (faba bean (Vicia faba), fenugreek (Trigolia foenum-graecum), common vetch (Vicia sativa), lentil (Lens culinaris), lupin (Lupinus albus), and pea (Pisium sativum)) were compared to barley (Hordeum vulgare). Summer legumes (chickpea (Cicer arietinum), common bean (Phaseolus vulgaris), soybean (Glycine max) and Narbonne vetch (Vicia narbonensis)) were compared to sorghum (Sorghum bicolor). Inorganic N remaining in the soil at pre-crop harvest (N sparing) was measured. The STICS model which accurately predicted soil humidity and soil inorganic N in the pedoclimatic conditions of the field experiments was used to calculate N mineralisation from pre-crop residues and N leaching between pre-crop harvest and wheat harvest. Grain and shoot N yields of unfertilised N wheat were respectively 27 and 25 % higher after faba bean and lentil compared to barley pre-crops, and 66 and 51 % higher after summer legumes compared to sorghum pre-crop. In the second experiment, N fertilisation reduced the positive effect of fenugreek, and lentil on wheat yield compared to barley while it did not modify the pre-crop effect of the other legumes. A positive relationship between N mineralisation from pre-crop residues and wheat shoot N yield was established, with higher amounts of N available for the subsequent wheat after legume pre-crops. In 2014, N sparing was higher after spring pre-crops compared to summer pre-crops inducing higher N leaching after spring legume pre-crops, especially in the first experiment which was characterised by heavy rain in summer and autumn. Estimating N availability by taking into account N sparing, N mineralisation from soil and pre-crop residues and N leaching explained 49 % of wheat shoot N yield variability. Unquantified N processes and non-N processes might also have contributed to the positive effects of legumes on the subsequent wheat.

Why did the invasive walking catfish cross the road? Terrestrial chemoreception described for the first time in a fish.

Clarias batrachus (walking catfish) is an invasive species in Florida, renowned for its air-breathing and terrestrial locomotor capabilities. However, it is unknown how this species orients in terrestrial environments. Furthermore, while anecdotal life history information is widespread for this species in its nonnative range, little of this information exists in the literature. The goals of this study were to identify sensory modalities that C. batrachus use to orient on land, and to describe the natural history of this species in its nonnative range. Fish (n = 150) were collected from around Ruskin, FL, and housed in a greenhouse, where experiments took place. Individual catfish were placed in the center of a terrestrial arena and were exposed to nine treatments: two controls, L-alanine, quinine, allyl isothiocynate, sucrose, volatile hydrogen sulphide, pond water and aluminium foil. These fish exhibited significantly positive chemotaxis toward alanine and pond water, and negative chemotaxis away from volatile hydrogen sulphide, suggesting chemoreception - both through direct contact and through the air - is important to their terrestrial orientation. Additionally, 88 people from Florida wildlife-related Facebook groups who have personal observations of C. batrachus on land were interviewed for information regarding their terrestrial natural history. These data were combined with observations from 38 YouTube videos. C. batrachus appear to emerge most frequently during or just after heavy summer rains, particularly from stormwater drains in urban areas, where they may feed on terrestrial invertebrates. By better understanding the full life history of C. batrachus, we can improve management of this species.

A multi-method monitoring of timing, magnitude and origin of rockfall activity in the Japanese Alps

A multi-method monitoring was conducted to detect the timing and trigger of rockfall activity on an alpine rockslide cliff composed of Cretaceous sandstone and shale in the southern Japanese Alps (Aresawa rockslide, 2900 m above sea level). The monitoring programme includes manual measurements of flaking from painted rock surface and collection of fallen debris, daily time-lapse imaging of the rockwall, automated recordings of rock temperature, rock moisture and influencing meteorological factors (air temperature and precipitation). A stereographic pair of sequential photographs is used to visually identify the location of new erosion and semi-quantitative evaluation of detached materials at daily resolution. Six years (2010–2016) of debris trapping show major rockfall activity in winter (between November and May) and occasional activity associated with heavy rains in summer, and yield an average rate of rockwall retreat on the order of 1 mm a−1. The rockwall shows heterogeneous debris production mainly reflecting joint spacing. Time-lapse imaging displays at least 10–15 rockfall events per year within the shot area (~500 m2). The integration of multiple data suggests at least five types of triggering processes towards rockfalls, which recur annually. (1) In summer and early autumn, heavy rainfalls raise the moisture content of the shallow bedrock, often triggering significant rockfalls, probably due to raised water pressure in rock joints or lubrication of joints. (2) In late autumn and late spring, light or intermediate rainfalls are sometimes followed by high moisture, shallow freezing, rapid thawing and eventually by different scales of rockfalls. (3) In winter and early spring, the same process as in the second case, but rainfall is replaced by snowfall, triggers submeter-scale rockfalls. (4) Deep seasonal freezing to about 5 m enables release of meter-scale rockfalls during seasonal thawing periods from late spring to early summer. (5) Short-term large thermal fluctuations that produce cyclic thermal stress may also contribute to submeter-scale rockfalls, mainly in winter locally enhanced by freeze-thaw action.

Potential influences of neglecting aerosol effects on the NCEP GFS precipitation forecast

Abstract. Aerosol–cloud interactions (ACIs) have been widely recognized as a factor affecting precipitation. However, they have not been considered in the operational National Centers for Environmental Predictions Global Forecast System model. We evaluated the potential impact of neglecting ACI on the operational rainfall forecast using ground-based and satellite observations and model reanalysis. The Climate Prediction Center unified gauge-based precipitation analysis and the Modern-Era Retrospective analysis for Research and Applications Version 2 aerosol reanalysis were used to evaluate the forecast in three countries for the year 2015. The overestimation of light rain (47.84 %) and underestimation of heavier rain (31.83, 52.94, and 65.74 % for moderate rain, heavy rain, and very heavy rain, respectively) from the model are qualitatively consistent with the potential errors arising from not accounting for ACI, although other factors cannot be totally ruled out. The standard deviation of the forecast bias was significantly correlated with aerosol optical depth in Australia, the US, and China. To gain further insight, we chose the province of Fujian in China to pursue a more insightful investigation using a suite of variables from gauge-based observations of precipitation, visibility, water vapor, convective available potential energy (CAPE), and satellite datasets. Similar forecast biases were found: over-forecasted light rain and under-forecasted heavy rain. Long-term analyses revealed an increasing trend in heavy rain in summer and a decreasing trend in light rain in other seasons, accompanied by a decreasing trend in visibility, no trend in water vapor, and a slight increasing trend in summertime CAPE. More aerosols decreased cloud effective radii for cases where the liquid water path was greater than 100 g m−2. All findings are consistent with the effects of ACI, i.e., where aerosols inhibit the development of shallow liquid clouds and invigorate warm-base mixed-phase clouds (especially in summertime), which in turn affects precipitation. While we cannot establish rigorous causal relations based on the analyses presented in this study, the significant rainfall forecast bias seen in operational weather forecast model simulations warrants consideration in future model improvements.

СИЛЬНІ ЗЛИВИ НА ТЕРИТОРІЇ УКРАЇНИ НА РУБЕЖІ ХХ – ХХІ СТОЛІТЬ

Long-term dynamics and spatial and temporal distribution of heavy showers in Ukraine are investigated in conditions of global warming. Heavy showers often fall between May and August, their maximum observed in the summer months (July). However in recent years, heavy rain began to observe in April, September and October. In the 2001-2010s frequency of heavy showers has more than doubled over the previous decade. Most cases of heavy rains at all time periods observed in the Crimea peninsula and Odessa region. The lowest number of showers for the period 1986-2015 is registered in Rivne and Lugansk regions. The analysis of atmospheric circulation conditions that cause heavy rains is carried out. Most cases of heavy rains in summer associated with isolated upper-tropospheric cyclones (cut-off lows) that generally sedentary and make long-term impact on the study area, mainly in the first half of summer. In late summer, heavy showers associated with synoptic processes in interaction with the quasi-stationary ridge over Eastern Europe.

Datación de avenidas torrenciales y flujos de derrubios mediante metodologías dendrogeomorfológicas (barranco de Portainé, Lleida, España)

García–Oteyza, J., Génova, M., Calvet, J., Furdada, G., Guinau, M., Díez-Herrero, A. 2015. Dating flash floods and debris flows through dendrogeomorphological methodologies (Portainé stream, Lleida, Spain). Ecosistemas 24(2): 43-50. Doi.: 10.7818/ECOS.2015.24-2.07 Dendrogeomorphology is a very useful tool in the scientific-technical analysis of floods and debris flows in high mountain streams, where conventional sources of data (discharges or rainfall) are scarce or non-existent and certain social problems arise. The Portainé stream, whose head the eponymous ski station Port Aine (Lleida, Spain), meets these characteristics. Erosional and depositional phenomena associated mainly with periods of heavy summer rains, periodically affect the access road to the ski station, which crosses the stream at various points, with consequent economic losses and personal and services potential danger. This work aims to estimate, by dendrogeomorphological techniques, the number and time distribution of floods and torrential flows into the stream, to evaluate if anthropogenic interactions in the hydrographic network, associated with the opening and operation of the ski station and its access, may have changed their frequency. Tree specimens exhibiting obvious external damage caused by the impact of materials dragged through the torrential floods were sampled. A detailed geomorphological study was also conducted and the historical data available were compiled. With all this information a database of past flood events for a period of 50 years was generated, which has resulted in a significant increase of these events in recent decades.

Determining Variability in Characteristics of Residential Landscape Soils that Influences Infiltration Rates

Although composed mostly of sand, observations of new urban residential communities in Florida suggested relatively wide ranges in clay content and importation of offsite soils. Often these communities are constructed around surface water where heavy summer rains and intense landscape maintenance present concerns for surface water contamination. Due to land sculpturing, soil compaction and importation; onsite soil physical properties may differ from soil maps developed decades before. How much change and what changes occurred has seldom been quantified. This study examined soil characteristic data from diverse, newly constructed urban soils and examined relationships with soil infiltration rates. Samples were collected from 40 lots in nine newly established urban residential communities within Central Florida to quantify textural composition, bulk density (Db), moisture retention, and pore size distribution. Most lots (90%) contained sandy soil dominated by micropores (58% total mean pore space). Variability of Db was low with most communities exhibiting high soil compaction (&gt;1.7 g cm-3), which may indicate potential plant root penetration concerns. Mean soil infiltration rates among communities were high (11 to 64 cm hr-1), with large variations (2.0 to 111.1 cm hr-1). Correlations between soil moisture retention volumes, Db, and infiltration rate did not occur. However, soil texture was a significant predictor of infiltration rate. Relationships between infiltration rates and soil characteristics were poor (r2 = 0.43) and suggest direct measurement of infiltration rate may be necessary. High infiltration rates, despite compaction, indicate reduced potential for surface water contamination if a sufficient natural fetch separates landscapes from water bodies.

The palaeoenvironmental significance of δ13C of stalagmite BW‐1 from Beijing, China during Younger Dryas intervals inferred from the grey level profile

High‐resolution records of carbon isotope composition and grey level were analysed from a stalagmite, BW‐1, from Beijing, China, deposited between c. 14 and 10.5 ka BP, the δ18O profile of which has been used to discuss the timing and structure of the Younger Dryas (YD) event in north China. The high grey level and low δ13C match the milk‐white coloured locations on the polished stalagmite surface and coincide with enhanced luminescent bands within which the concentration of both impurities and the total organic carbon (TOC) are high. Additionally, the fluorescence of speleothems was derived from organic acids that have been flushed onto the stalagmite surface along with impurities from the overlying soil by heavy summer rain and co‐precipitated with the speleothem calcite. Thus, predominantly low δ13C and high grey level values indicate increased summer precipitation that supports abundant vegetation and robust biological productivity. Consequently, three distinct time intervals are defined by the palaeoenvironmental conditions expressed in the δ13C and grey level records of stalagmite BW‐1: (i) a warm‐humid stage (Pre‐YD, 13.97 to 12.85 ka BP, including a hiatus from 12.99 to 13.21 ka BP reported before); (ii) a cool‐arid stage (YD, 12.85 to 11.56 ka BP); and (iii) a warm‐humid stage (Post‐YD, 11.56 to 10.39 ka BP). The inferences based on our research are generally consistent with other regional vegetation and climatic records.

Development of a halotolerant community in the St. Lucia Estuary (South Africa) during a hypersaline phase.

BackgroundThe St. Lucia Estuary, Africa's largest estuarine lake, is currently experiencing unprecedented freshwater deprivation which has resulted in a northward gradient of drought effects, with hypersaline conditions in its northern lakes.Methodology/Principal FindingsThis study documents the changes that occurred in the biotic communities at False Bay from May 2010 to June 2011, in order to better understand ecosystem functioning in hypersaline habitats. Few zooplankton taxa were able to withstand the harsh environmental conditions during 2010. These were the flatworm Macrostomum sp., the harpacticoid copepod Cletocamptus confluens, the cyclopoid copepod Apocyclops cf. dengizicus and the ciliate Fabrea cf. salina. In addition to their exceptional salinity tolerance, they were involved in a remarkably simple food web. In June 2009, a bloom of an orange-pigmented cyanobacterium (Cyanothece sp.) was recorded in False Bay and persisted uninterruptedly for 18 months. Stable isotope analysis suggests that this cyanobacterium was the main prey item of F. cf. salina. This ciliate was then consumed by A. cf. dengizicus, which in turn was presumably consumed by flamingos as they flocked in the area when the copepods attained swarming densities. On the shore, cyanobacteria mats contributed to a population explosion of the staphylinid beetle Bledius pilicollis. Although zooplankton disappeared once salinities exceeded 130, many taxa are capable of producing spores or resting cysts to bridge harsh periods. The hypersaline community was disrupted by heavy summer rains in 2011, which alleviated drought conditions and resulted in a sharp increase in zooplankton stock and diversity.Conclusions/SignificanceDespite the current freshwater deprivation crisis, the False Bay region has shown to be resilient, harboring a unique biodiversity with species that are capable of enduring harsh environmental conditions. However, further freshwater deprivation may extend beyond the physiological thresholds of this community, as well as other unique biodiversity components which this system sustains.

Persistent Phytoplankton Bloom in Lake St. Lucia (iSimangaliso Wetland Park, South Africa) Caused by a Cyanobacterium Closely Associated with the Genus Cyanothece (Synechococcaceae, Chroococcales)

Lake St. Lucia, iSimangaliso Wetland Park, South Africa, is the largest estuarine lake in Africa. Extensive use and manipulation of the rivers flowing into it have reduced freshwater inflow, and the lake has also been subject to a drought of 10 years. For much of this time, the estuary has been closed to the Indian Ocean, and salinities have progressively risen throughout the system, impacting the biotic components of the ecosystem, reducing zooplankton and macrobenthic biomass and diversity in particular. In June 2009, a bloom of a red/orange planktonic microorganism was noted throughout the upper reaches of Lake St. Lucia. The bloom persisted for at least 18 months, making it the longest such bloom on record. The causative organism was characterized by light and electron microscopy and by 16S rRNA sequencing and was shown to be a large, unicellular cyanobacterium most strongly associated with the genus Cyanothece. The extent and persistence of the bloom appears to be unique to Lake St. Lucia, and it is suggested that the organism's resistance to high temperatures, to intense insolation, and to hypersalinity as well as the absence of grazing pressure by salinity-sensitive zooplankton all contributed to its persistence as a bloom organism until a freshwater influx, due to exceptionally heavy summer rains in 2011, reduced the salinity for a sufficient length of time to produce a crash in the cyanobacterium population as a complex, low-salinity biota redeveloped.

A Study on Management of Vegetation and Restoration in Abandoned Coal-Mine Waste Areas by Phytoremediation

In Okdong coal mine abandoned area, every year large amount of mine wastes have been swept away due to heavy rains in summer. Because pH of coal-mine waste is in the early 4, plant naturally does not grow there due to unfavorable condition for growing plant. This study had an experiment to grow plant for 6 months using Mycorrhizae which can be adapted well in acid soil. As a result of Experiment, In the infected experiment pot, 90% of the plants survived but in case of uninfected experiment pot, only 25% were alive. From Growth Experiment, it appeared that average stem length increase (cm/month), average fresh weight increase (g fw /month), average dry weight increase (g dw /month) were increased by 60%, 21%, 31% respectively. Especially, Mycorrhizae plays an important role in providing nutrients and water when seeding are established. Mycorrhizae prevents death caused by lack of nutrients and water and helps growth and development of plant when seeding are established in the early stage. This study proved that Mycorrhizae is comparatively effective in plant growth and prevention of erosion in coal-mine abandoned area.

Removal of Wet Deposited Phakopsora pachyrhizi Urediniospores from Soybean Leaves by Subsequent Rainfall

Urediniospores of Phakopsora pachyrhizi, the soybean rust fungus, have a high probability of being removed from a soybean leaf by water runoff associated with subsequent rainfall after wet deposition. The effects of rainfall intensity, subsequent spore-free rainfall duration, and soybean leaf sample height on uredinia density were used to evaluate the retention of urediniospores on soybean leaf tissue. Rainfall simulations of 45 and 85 mm/h were conducted on potted soybean plants that were inoculated with 2 min of urediniospore-injected simulated rainfall and exposed to 0, 1, and 30 min of subsequent spore-free rainfall. Urediniospore retention was estimated using uredinia density values obtained from a detached leaf bioassay for the sample heights of soil level, mid-canopy, and upper-canopy. Soil level leaflets inoculated with the 45 mm/h rainfall intensity treatment had a higher (P < 0.01) mean number of uredinia/cm2 than the 85 mm/h treatment, even though they were inoculated with approximately 40% fewer urediniospores. Subsequent spore-free rainfall reduced (P < 0.01) uredinia density by as much as 38 and 91% for the 1- and 30-min durations, respectively. The relationship between uredinia density proportion and depth of rainfall was best fit using an inverse power empirical model. Our results indicate that a majority of the wet deposited P. pachyrhizi urediniospores would be removed from soybean leaf surfaces by subsequent rainfall, but sufficient percentages of spores (10 to 25%) will likely remain on the leaf tissue long enough to germinate and infect during heavy summer rains lasting ≥30 min.