Decrease In Water Level Research Articles

A Methodology for Water Resource Management and the Planning of the Coastal Reservoir in Indonesia

Metropolitan areas in Indonesia, specifically Jabodetabek, are projected to continue experiencing population growth. This will result in increased water demand, which, if left unchecked, could lead to a water crisis. Additionally, the region faces persistent flooding issues. To mitigate these challenges, the Indonesian government proposes the creation of a coastal reservoir. However, a methodology for the pre-feasibility study of such reservoirs in Indonesia is currently lacking. This study addresses this gap by presenting a methodological framework encompassing hydrology and water allocation analyses as well as numerical modeling related to hydraulic and sedimentation aspects of coastal reservoirs. The methodology was designed to be adaptable based on data availability. Finally, this methodology was applied to a case study located at the Cisadane River estuary. The water allocation simulation showed that the reservoir can release an annual optimum discharge of 80.618 m3/s in wet years and 22.731 m3/s in dry years. Flood modeling demonstrated a modest impact on reducing early-hour floods, with a water level decrease of around 20–50 cm within 5 km of the reservoir. Furthermore, sediment modeling revealed varying sedimentation and erosion depths along the rivers, with approximately 62,300 m3/year settling in the reservoir.

The Latent Threat in Wild Birds: Clostridium botulinum.

Avian botulism caused by Clostridium botulinum emerged in 1910, affecting birds across North America, leading to severe outbreaks exacerbated by climate change, decreasing water levels, and inadequate wastewater management. While deadly for birds, its epidemiological impact on humans and other animals remains limited. Despite its significance, understanding and controlling the disease remain challenging. This review delves into the pathogen's epidemiology in wild bird populations, exploring the transmission, pathogenicity, clinical symptoms, diagnosis and treatment. The disease's growing concern in wild birds relates to the bacterium's adaptability and expansive spread, evident through genetic similarities among strains across countries. Outbreaks are influenced by environmental factors such as temperature and soil characteristics. Wild birds inadvertently transmit the bacterium, perpetuating the cycle through carcasses and flies. Some species suffer severely, while others, like scavengers, show resistance. Understanding disease mechanisms, involving potential toxin ingestion or internal production, remains ongoing. Clinical signs vary, affecting diverse bird orders. Diagnostic methods evolve, with treatment success varying among affected populations. Prevention and surveillance take precedence due to treatment challenges, emphasising population-based strategies and preventive measures to manage the widespread presence of C. botulinum.

ВЫЯВЛЕНИЕ ПАЛЕОГИДРОДИНАМИЧЕСКИХ ОБСТАНОВОК ОСАДКОНАКОПЛЕНИЯ ПО ДАННЫМ ГРАНУЛОМЕТРИЧЕСКОГО АНАЛИЗА ДОННЫХ ОТЛОЖЕНИЙ МАЛЫХ ОЗЕР ШОКШИНСКОЙ ГРЯДЫ (КАРЕЛИЯ)1

The paper examines the grain size distribution of bottom sediments of lakes in the Shoksha Ridge area, Karelia, to elucidate howdeglaciation and formation of the Onego Ice Lake basin proceeded. A sequence of bottom sediments of Lake Anashkino and two sediment sequences of Lake Rzhanoe were studied, and lithostratigraphy of the sediment cores was described. The grain size compositions of the 9.32-10.32m sequence from Lake Anashkino and the 2.5-6.52 m sequence from Lake Rzhanoye were analyzed. The study revealed features of the bottomsediment fractions distribution along the depth of occurrence. Paleo-hydrodynamic sedimentation environments were identified using grain sizeanalysis. Lake Anashkino bottom sediments of a 9.96–10.31 m horizon, represented by silt and fine-grained sand, were deposited under conditions of highly dynamic shallowing (decrease in the water level of Onego Ice Lake). The upper part of sediments (9.32–9.92 m), represented by clayey silt mixed with fine-grained sand, accumulated under weak flow conditions. Paleo-hydrodynamic sedimentationenvironments in Lake Rzhanoye were characterized by alternation of highflow conditions (5.36-6.23 m, 6.31-6.32 m, 6.47-6.48 m) and weak flowconditions (2.50-4.88 m, 6.28-6.29 m, 6.30-6.31 m, 6.37-6.45 m, 6.51-6.52 m). This is possibly due to the dynamics of the decrease in the waterlevel of Onego Ice Lake and the formation of small isolated lakes.In the process of the formation of bottom sediments of small lakes of the Shoksha Ridge during the period of intensive changes in thelandscapes, outlines and levels of Onego Ice Lake at the transition from the late Pleistocene to Holocene, against a shift from nival to humid climate,we note a change in sedimentation conditionsin the bottom sediments of the two studied lakes – Anashkino and Rzhanoe – from highly dynamic(flowing conditions, decrease in water level of Onego Ice Lake) to weakly flowing, in the conditions of isolation of the lakes and formation ofmodern small lakes.

ОЦЕНКА МОРФОМЕТРИЧЕСКИХ ПАРАМЕТРОВ ОЗЕР БОЛОТНЫХ КОТЛОВИН СЕВЕРА ПЕРМСКОГО ПРИКАМЬЯ

The lakes of bog depressions in the north of the Perm Kama region are relatively inaccessible and insufficientlystudied. The interest in studying these lakes is due to the relict character of their formation in the bowls of glacial lakes as well as themodern climatic instability. On the basis of direct field studies (bathymetric surveys in 2021 and 2023) and remote sensing data processing, we studied 12 lakes of bog depressions. This paper is the first to provide a calculation of a set of morphometric data of thewater bodies: length, maximum and average width, area, extent, shoreline sinuosity coefficient and others. For lakes Adovo,Chelvinskoye and Nyukhti, the maximum and average depths and the total volume of the water body were also determined. It is notedthat the pronounced climatic features of 2023 (hot and dry year) could lead to a noticeable decrease in water level, especially in LakeNyukhti. In this case, the obtained values of the water body depths and volume are reduced relative to the norm. It was also found thatin the data of the State Water Register, used as reference, the water area for Lake Bolshoi Kumikush is significantly underestimated(by 3.2%), while for lakes Chusovskoye and Tundra – significantly overestimated (by 22.2% and 34.2%, respectively). The study hasestablished the place of the water bodies in question in the rows of lake classification by area, depths, elongation index, and the shorelinesinuosity.

The drying of Lake Urmia and its consequences for waterbird assemblages

Summary The hypersaline Lake Urmia, located in Iran, has undergone a significant reduction in size and is currently facing the risk of desiccation. The decrease in water levels, coupled with elevated salinity levels, has initiated ecological degradation, leading to a substantial decline in the region’s waterbird population. This study employs breakpoint analysis to determine the year when the drought event affecting the lake commenced. Additionally, canonical correspondence analysis (CCA) is utilised to elucidate the interaction between environmental parameters and the waterbird assemblages in Lake Urmia over the period 1970–2018. Our investigation identifies the year 2000 as the initiation of the water crisis in Lake Urmia, synchronously coinciding with the decline in the waterbird populations. This finding highlights a significant connection between the majority of waterbird species and the axes of CCA, intricately linked with water availability within Lake Urmia. This revelation underscores the pivotal role of fluctuations in water levels in shaping the dynamics of the lake’s waterbird assemblages. Furthermore, our observations emphasise the importance of even minor improvements in hydrological conditions of the lake, resulting in substantial positive impacts on waterbird populations.

Development of Low-Cost IoT System for Monitoring Piezometric Level and Temperature of Groundwater

Rural communities in Mexico and other countries with limited economic resources require a low-cost measurement system for the piezometric level and temperature of groundwater for their sustainable management, since anthropogenic action (pumping extractions), natural recharge and climate change phenomena affect the behavior of piezometric levels in the aquifer and its sustainability is at risk. Decrease in the piezometric level under a balanced level promotes salt intrusion from ocean water to the aquifer, salinizing and deteriorating the water quality for agriculture and other activities; and a decrease in water level under the pumps or well drilling depth could deprive communities of water. Water temperature monitoring is essential to determine electric conductivity and dissolved salt content in groundwater. Using IoT technology, a device was developed that monitors both variables inside the well, and the ambient temperature and atmospheric pressure outside the well. The measurements are made in real time, with sampling every second and sending data to a dedicated server every 15 min so that the visualization can be accessed through a device with Internet access. The time series of the variables measured inside and outside the well were obtained over a period of three months in the rural community of Agua Blanca, Guasave, Sinaloa, Mexico. Through these records, a progressive temporary drawdown of the piezometric level is observed, as well as the frequency of pumping. This low-cost IoT system shows potential use in hydrological processes of interest such as the separation of regional and local flow, drawdown rates and recognition of geohydrological parameters.

Spectral Response at Different Water Depth Standing in the Field

Water availability and irrigation management can be estimated in agricultural fields through observation of field water storage. In order to calculate runoff and recharge through these fields, the water depth stored in the haveli fields must meet certain requirements. Remote Sensing data obtain through Satellite in all visible and NIR region might be helpful for such requirements. An experimental study is made to assess the utility of different bands for depicting depth of storage in field. Spectral reflectance was recorded on different depth from 0 to 100 cm of water. Ground Truth Radiometer (GTR) was used to conduct the experiment. Experimental observation shows the variation in reflectance with different depth of water stored in 1 m3 ponding water. It has been observed that spectral response shows variation under different storage level and different time of observation. To minimize error on observation the readings were taken under uniform sunshine condition and wind velocity. The Radiation under wavelength 0.4 and 1.1 µm was used to collect response in reflectance from experimental fields. The increase in reflectance with was observed with decrease in water level. This could be due to visibility of bottom soil in lower depths. A comparison between experimental response data and satellite image data of indicate that there is variation on band 4 and similar trend on band 1, 2. Mixed tread was observed in band 3. A clear decrease in reflectance up to 50 percent was observed when water storage depth increase up to 90 cm but then it started increasing. Similar variation was observed for observation with a depth of more than 1 m. Satellite data is more stable as compared to GTR data.

<i>Najas marina</i> (Hydrocharitaceae) in Southern Middle Siberia, Refinds after a Century-Old Recess<sup>1</sup>

In the south of the Krasnoyarsk Territory (Middle Siberia, Russia), the presence of N. marina was confirmed by new findings, in addition to historical collections, which were made more than 100 years ago in the South-Minusinsk basin. We have found this species additionally in three lakes in the North-Minusinsk basin, which are the northernmost localities in the Krasnoyarsk Territory. According to our findings, published data, and herbarium collections from Middle Siberia and adjacent regions, all specimens of large Najas belong to N. marina s. str. The species occur in lakes situated in landscapes with marine and lacustrine deposits in intermountain depressions with a continental arid climate. The increase of aridity of climate in southern Siberia will contribute to competitive advantages for populations of N. marina, their emerging and distribution in the studied area in connection with decreasing water level and increasing salinity which happen time to time and has fluctuating character.

Response of the nitrogen processing bacterial community to water level fluctuation and nitrate availability in an intact marsh soil column.

Wetlands are known to experience fluctuations in water levels and receive exogenous nitrogen inputs that affect various organisms, including soil microorganisms. To study the impact of these factors on microbial diversity, we collected intact soil columns from a Phragmites australis-dominated site in the Qixing River National Nature Reserve in Northeast China. In a laboratory experiment, we simulated water level fluctuations and exogenous nitrogen inputs to the soil columns and examined the associated changes in the relative abundance of 51 bacterial genera involved in nitrogen cycling processes. Our findings revealed that different bacterial genera exhibited varying relative abundances across treatments. Specifically, Massilia showed the highest total relative abundance at the genus level, while Planctomyces had the second highest, and Campylobacter had the lowest abundance. The DESeq2 model, based on negative binomial distribution, revealed that the tags of bacterial genera were significantly correlated with soil depth, but not with water levels or nitrogen concentrations. However, the addition of a 30mg/L nitrate solution caused a decrease in the relative abundances of bacterial genera with decreasing water levels, while a 60mg/L concentration of nitrogen resulted in a decrease and then an increase in the relative abundances of bacterial genera with decreasing water levels. Our study provides valuable insights into the response of nitrogen-cycling bacteria to changes in different environmental conditions.

Research and Application of Intelligent Water Source Well Air Defense Pumping and Dry Burning Technology

The surface water injection technology for developing low permeability reservoirs comes from the water supply of water source wells. The groundwater resources in oil fields are limited, with high water consumption and a decrease in water level, lacking effective monitoring methods. In recent years, there have been frequent occurrences of unsafe waste of electrical energy due to dry burning during pumping in water source wells, which has seriously affected the normal water injection of oilfield formations. In order to prevent dry burning of water source wells by pumping air, research on intelligent air defense dry burning technology for water source wells has been carried out. The automatic pump stop alarm at low water level and the automatic pump start at high water level avoid the phenomenon of dry burning during pumping in the water source well, ensure the normal operation of the water source well, and ensure sufficient water injection from the source. Reduce employee labor intensity and achieve the goal of optimizing human resources. Associate the start and stop status of the water source well with the tank position of the water injection station to achieve automatic water distribution and inventory, achieve digital management and fine management, and achieve the goal of reducing costs and increasing efficiency, which has promotion value.

Inter-annual changes of zooplankton in the kultuk zone of the Volga River delta in the spring period

The studies conducted in spring have shown the main trends in changes in the structure of zooplankton in the kultuk zone of the Volga River delta in years that differ in hydrological and temperature regimes. It was revealed that in low-water years (2012, 2014), with a decrease in the volume of runoff, water level, and a reduction in the duration of floods, zooplankton was characterized by relatively low species richness, high biomass of Copepoda and Cladocera. At the same time, the highest rates of specific species richness, biomass and abundance of all zooplankton groups were observed at spring of a low-water year (2014), which was characterized by a runoff volume during the flood of 101 km3, a high pre-flood water levels, the absence of a sharp and significant dilution, as well as an early warm spring and gradual warming of the waters. In the year (2012), characterized by a volume of runoff during the flood period of 114 km3, a decrease in water level and a sharp increase in temperature before the flood, and then its rapid rise with dilution by cold waters, zooplankton was distinguished by the minimum species richness, a low number of ecological groups and low abundance of Cladocera, but a high proportion of juvenile copepods (fine filter feeders) and in terms of biomass of active euryphagous predators and euryphagous collectors. In a medium-water year (2013) with a large volume of runoff during the flood of 140 km3, with early and high and long floods, zooplankton was distinguished by a high total number of species encountered, but a minimum abundance and biomass, which is associated with the “dilution effect” and an increase in the areas of flooded rich in higher aquatic vegetation.

Estimation of Changes in Sediment Transport along the Free-Flowing Middle Danube River Reach

The subject of this study is an approximately 300 km long Middle Danube River reach that spans from river kilometer (rkm) 1581 in Hungary to (rkm) 1255 in Serbia. The observed drying of floodplains in Hungary some thirty years ago initiated the hydrological studies. However, problems related to the navigation route maintenance of the Danube River and those in the water supply of irrigation and drainage canal networks are now present in the whole free-flowing middle Danube region. The study aims at investigating the correlation between the observed water level decrease and recorded incision of the river bed at gauging stations and the indirect estimation of the long-term sediment transport along the sand-bed reach based on the surveillance cross-sections’ data collected during regular monitoring surveys on the navigable Danube. It starts with hydrological analyses of the 70-year-long time series of water level and discharge yearly data and continues with morphological and correlation studies. It ends with the estimation of sediment transport. The decreasing trend in water levels and the increasing trend in cross-sectional areas are persistent. There is a linear correlation between the two. Longitudinal changes in sediment transport indicate the existence of both degrading and aggrading riverbed reaches.

Dam Surface Deformation Monitoring and Analysis Based on PS-InSAR Technology: A Case Study of Xiaolangdi Reservoir Dam in China

The Xiaolangdi Dam is a key project for the control and development of the Yellow River. It bears the functions of flood control, controlling water and sediment in the lower reaches, ice prevention, industrial and agricultural water supply, power generation, and so on. Its safety is related to people’s life and property safety and local economic and social development. It is of great significance to carry out comprehensive and regular deformation monitoring for dams since the deformation is an important evaluation index for dam safety. Interferometric Synthetic Aperture Radar (InSAR) technology has been a rapidly evolving technology in the field of space geodesy in recent years. It offers advantages such as high monitoring precision, extensive coverage, and high monitoring point density, making it a powerful tool for monitoring deformations in hydraulic engineering projects. Based on Sentinel-1 data covering the Xiaolangdi Dam from September 2020 to November 2022, the PS-InSAR technique was used to obtain the surface deformation of the Xiaolangdi Dam, and reservoir water level data on image acquisition dates were obtained for joint analysis. The results show that there is a large deformation in the center of the dam crest of the Xiaolangdi Dam, while both sides of the slope and downstream dam foot are relatively stable. The time series deformation of the dam body is closely related to the reservoir water level change. When the water level increases, the dam body tends to deform downstream; when the water level decreases, the dam body tends to deform upstream. The deformation and water level of the Xiaolangdi Dam exhibit a clear negative correlation. There is no significant cumulative deformation on the dam slopes or at the base of the dam. However, cumulative deformation occurs over time in the central area of the dam’s crest. The deformation process at the central area of the dam’s crest follows a continuous and non-disruptive pattern, which is consistent with the typical deformation behavior of the Xiaolangdi earth–rock dam structure. Therefore, it is judged that the current deformation of the Xiaolangdi Dam does not impact the safe operation of the dam. InSAR technology enables the rapid acquisition of high-precision, high-density deformation information on the surfaces of reservoir dams. With an increasing number of radar satellites in various frequency bands, such as Sentinel-1 and TerraSAR-X, there is now an ample supply of available data sources for InSAR applications. Consequently, InSAR technology can be extended to routine monitoring applications for reservoir dam deformations, especially for small and medium-sized reservoirs that may not be equipped with ground measurement tools like GNSS. This holds significant importance and potential for enhancing the safety monitoring of such reservoirs.

Statistical Analysis of the Hydrological and Hydrometeorological Characteristics of the Upper Tisza Basin

Tisza is the largest water base in the eastern part of Szabolcs-Szatmár-Bereg County, in north-eastern Hungary, and its indirect use is mainly associated with agriculture. Our work investigates the hypothesis that decrease in water levels and water discharges of the Upper Tisza in recent decades, together with the incision of the riverbed and the precipitation falling in the area, have an impact on the groundwater level of the Szatmár-Bereg Plain. In our study, data from three water gauges located between the settlements of Tiszaújlak and Vásárosnamény and data from groundwater level monitoring wells (MW) and Hydrometeorological (HMS) stations on the Szatmár-Bereg Plain were compared using statistical methods in Past 4.11 software. The aim of the current study was to identify the strategic steps that need to be taken by the organisations responsible for water management in the Upper Tisza basin in the light of the changes in hydrological, hydrometeorological, and meteorological factors. To ensure that the region has sufficient water supplies for the next decade, appropriate water management and agricultural strategies could be the solution.

Effect of Cut-Off Irrigation levels on Production of Teosinte Forage Crop in Clay Soil

The present study was carried out at Sakha Agricultural Research Station (clay soils) middle north of Nile Delta area during summer seasons 2021 and 2022 in randomized complete block design with three replications. The objective of this research was to find out the response of yield, water saving and some water functions for teosinte forage crop to cut-off surface irrigation owing to produce " more per less”. Three irrigation levels were executed; 100% i.e., full irrigation, 90% cut-off irrigation and 80% cut-off irrigation. The mean performances of plant height, fresh and dry forage yields in the two seasons and combined are significantly affected by irrigation levels applied, whereas normal or control treatment with100% irrigation i.e., no cut-off (Trt. A) has the tallest of plant height. On the other hand, the low irrigation level with 80% cut-off (Trt. C) has the shortest plants at the three cuts. Also, traits reduced with the decrease of irrigation water level at the three cuts. Both fresh and dry forage yields are severely decreased when plants irrigated by 80% cut-off. Decreasing the irrigation water level than the commonly controlled of 100% without cut-off (Trt.A) markedly reduced all studied growth characters at the three cuts. The inhibiting effect of the water deficit stress on the studied parameters notably appeared more pronounced under the 80% cut-off than that of 90% .The obtained results may refer to that decreasing the irrigation water lowered the soil moisture content which restricted the mobility of nutrients to plant that would reduce the efficiency of physiological and metabolic processes needed for plant growth. Regarding water relations, irrigation with 90% cut-off resulted in several advantages; almost same yield as obtained under full irrigation, 10% water saving as well as the highest values of crop-water functions of water productivity (WP) and productivity of irrigation water (PIW). The mean values of fresh forage yield of 100% irrigation levels recorded 610 and 685 Kg/strip with compared to 585 and 655kg/strip for 90 %irrigation treatment at first and second cuts, respectively in the first season.

Decoding the hundred-year water level changes of the largest Saline Lake in China: A joint lake-basin modeling study based on a revised SWAT+

Study regionQinghai Lake Basin (QLB), the largest saline lake in China and its collecting basin Study focusClimate change has caused clear shrinkage or dramatic water level fluctuation of lakes in arid and semi-arid regions, while the underlain mechanisms remain unclear. The joint lake-basin investigations (spatial) and long-term studies (temporal) are urgently needed. This study developed SWAT+ to jointly simulate the water cycle of QLB and investigated how the hydrological regime of QLB changed at the hundred-year scale. New hydrological insights for the regionThe modeling framework consisted of the revised SWAT+ , reanalysis data, and reconstructed water level based on lake gravity core performed quite well (NSE > 0.9 for lake water level) in simulating the hydrological processes of QLB at the hundred-year scale (1910 – 2018). Temporally, decadal variations of hydrological components in QLB decreased in sequence of precipitation (46.33 mm), lateral flow (26.85 mm), evapotranspiration (16.03 mm), snowmelt (10.44 mm), groundwater flow (5.66 mm), and overland flow (1.18 mm). Spatially, precipitation, water yield, lateral flow, and groundwater flow in upstream regions of QLB, where the precipitation amount was small, were most sensitive to climate change. The long-term water level decrease of Qinghai Lake during 1928 – 2003 was mainly driven by variations of river runoff and lake surface evaporation; the clear water level increase since 2004 was dominated by river runoff changes.

Effects of Hydrological Drought Periods on Thermal Stability of Brazilian Reservoirs

Droughts can impact ecosystem services provided by reservoirs. Quantifying the intensity of droughts and evaluating their potential effects on the thermal stability of reservoirs are subjects that demand greater attention, due to both the importance of temperature on aquatic metabolism and the climate change scenarios that predict an increase in the frequency of extreme weather events. This study aimed to investigate drought periods in ten Brazilian reservoirs and to discuss their effects on each reservoir’s thermal stability. The Standardized Precipitation Index at a twelve month timescale (SPI-12) was applied to identify the hydrological drought periods. One-dimensional vertical hydrodynamic modeling was used to simulate the water balance and the thermal dynamics in the reservoirs. Schmidt Stability Index (St) was calculated to assess the thermal stability of the reservoirs. The drought periods identified by the SPI-12 are related to decreasing water levels of the reservoirs, but the dam operating strategies and the upstream influence of cascading reservoirs are important drivers of fluctuations. A significant difference in St between wet and dry conditions was found only during summer for all reservoirs. Thus, this study identified alterations in thermal regime during drought periods according to the seasons and the reservoirs characteristics.

Development of IOT-based low-cost MEMS pressure sensor for groundwater level monitoring

Groundwater level monitoring is critical to the protection and management of groundwater resources. Properly designed and executed instrumentation can play an important role in increasing the quality and reliability of collected data and reducing total monitoring costs. The efficiency of the instrumentation depends mainly on the accuracy and reliability of the installed sensors. This study presents the testing and application of a cost-effective pressure sensor (0–689 kPa range) for water level monitoring based on microelectromechanical system (MEMS) technology and the internet of things concept. The sensor performance, in terms of accuracy, precision, repeatability, and temperature, was investigated in laboratory columns (with constant water level, increasing and decreasing water levels at various rates) and in situ conditions in an observation bore (with natural groundwater level fluctuations). The results show that the MEMS sensor is capable of providing a reliable and adequate monitoring scheme with an accuracy of 0.31% full scale (FS) (2.13 kPa).

Numerical simulation of seawater intrusion in the lower Seybouse aquifer system, Algeria

Seawater intrusion represents a high risk for the water supply, the agriculture and industry activities in the lower Seybouse region of North-Eastern Algeria. In order to analyze this risk, a three-dimensional model was developed using the MODFLOW and MT3DMS codes to predict seawater intrusion in the coastal aquifer. The application of this model indicates that the groundwater withdrawals result in a continuous decrease of the water level and in an increase of chloride concentration. Moreover, the salt front could progress by 300 to 2500 m in the land. These results show the necessity of adequate measures for the protection of the aquifer. Numerical predictions for 2045, considering an increase of groundwater withdrawals by 20%, show a fairly significant decrease in water levels, up to -6 m with respect to the mean sea level, and an increase of Cl- concentrations up to about 10 km inland.

Adaptive plasticity in anuran metamorphosis: response of tadpoles of Polypedates maculatus (Anura: Rhacophoridae) to pond drying


 
 
 
 The influence of desiccation on metamorphic traits (larval duration and size at emergence) was studied in Polypedates maculatus under laboratory conditions. Gosner Stage 23 tadpoles were exposed to decreasing water levels (gradual or rapid) until the beginning of metamorphic climax (Stage 42). A control group was reared in constant water levels. Tadpoles reared in decreasing water levels reached the metamorphic climax earlier and metamorphosed at a smaller size than those reared in constant water levels. Further, tadpoles experiencing rapid depletion of water reached the metamorphic climax earlier and metamorphosed at a smaller size than those experiencing gradual depletion of water levels. Tadpoles of P. maculatus showed adaptive plasticity in metamorphosis to pond drying. Survival of tadpoles in treatments and the control was 100%. The study revealed that tadpoles of P. maculatus have plastic development in response to water levels; the trade-off between growth and development favors development, which results in early metamorphosis at a small size.