Watershed Ecology and the Environment最新文献

Land-use change refers to a change in how a particular area of land is utilised or managed by humans. Land-cover change refers to a change in some continuous features of the land, such as vegetation type, soil conditions, and so on. For the purpose of identifying change-vulnerable areas and creating sustainable ecosystem services, mapping and quantifying the state of land use/land cover (LULC) changes and change-causing factors are crucial. The present research utilizes a geographic information system (GIS) and remote sensing (RS) techniques to categorise and identify changes in a Murredu watershed in Telangana state, India, between 1996 and 2019. Five major LULC categories (agricultural land, forest, barren land, built-up area, and waterbodies) from satellite images of 1996 to 2019 were mapped. The maximum likelihood approach was used to supervise the classification process, and high-resolution Google Earth Pro was used to evaluate the accuracy of the classified map. The accuracy of the mapping was evaluated using the error matrix and Kappa statistics. Overall classification accuracy for the classified image of 2019 was found to be 90 % with overall kappa statistics of 85.98%. From these findings, change detection analysis shows that the area used for agricultural land, barren land, forest, built-up areas, and waterbodies has increased by 5.17%, 3.39%, 0.84%, and 0.26%, respectively, between 1996 and 2019. The forest area has decreased by 9.67% at the same time. Therefore, this research anticipates that the findings might provide information to planners, land managers, and decision-makers for the sustainable management and development of the natural resource.

Crabs are the most dominant groups in mangrove ecosystem and play a vital role in building and sustaining the structure and function of the mangrove ecosystems. However, a systematic evaluation of global research status of mangrove crabs is still lacking. Here, a bibliometric analysis based on the Science Citation Index Expanded (SCI-E) was carried out to provide insights into research activities, tendencies, and challenges of the mangrove crabs from 1980 to 2016. The results showed that the average annual output of the publications was low. Brazil took a leading position out of the 63 countries/territories with the largest number of publications, followed by USA, Australia, China, and Germany. Journal of Experimental Marine Biology and Ecology was the most popular journal. The reproductive ecology (e.g., reproduction), population ecology (e.g., population structure), and their relationship were the mainstream. The estuarine ecosystem and the method of stable isotope received ecologists’ favor. Behavioral ecology (e.g., bioturbation), ecosystem function (e.g., carbon), and the ecological effect among them were the main issues in this field. Biodiversity was a new hot topic. Brazil, Australia, USA, China, and Kenya were the top five hot regions among the 53 hot countries on a global scale. Different regions have different hot topics. The breeding ecology was the most popular theme in the Americas region, the ecological effects of crabs were the most hotstops in the Africa-East Asia region and the East and South Asia-Oceania region. The challenges of the development were not comprehensive and uneven on a global scale. There was a certain number of countries with mangrove distributions were still outside this field, such as most of the western and northeastern countries of Africa (e.g., Angola), some Central American countries (e.g., Guatemala), and some western and southeast Asian countries (e.g., Cambodia). Furthermore, we found that some topics were ignored or lagged in each territory. Our results highlight that the global research status of mangrove crab is still at a relatively backward stage, and regional development is extremely unbalanced.

We explored the potential for functional processes maintenance principles to be applied in coastal restoration. Greater bay areas are located in the transition zone between land and sea. Coastal wetlands play a key role in the ecological environment construction of greater bay areas. Due to the dual effects of high-intensity human activities and climate change, coastal wetlands in greater bay areas have suffered varying degrees of damage, including reduced area, habitat degradation, and impaired ecological functions. However, the research progress and development trend of restoration of damaged coastal wetland ecosystems has not yet been revealed, and the application theory of functional processes in coastal restoration is still unclear. Based on extensive literature research, our study reviewed the mechanisms and types of coastal wetland ecosystem restoration in greater bay areas. Coastal wetland ecosystem restoration technologies and methods are mainly based on the biological, hydrological, and chemical processes in greater bay areas. The current research progress and existing deficiencies of coastal wetland ecosystem restoration in greater bay areas are clarified. Combining years of research background in the coastal wetland field, focusing on the importance and criticality of coastal wetland functional processes to maintaining ecosystem functions, the main future research trends are proposed, which will solve the principal theory facing the restoration of coastal wetland ecosystems in greater bay areas. Our study will promote the application of new concepts and new techniques of coastal wetland restoration nationwide, and improve the overall level of ecological restoration in coastal wetland.

Grasslands are among one of the largest terrestrial biomes in the world, suffering severe threat from ongoing degradation. Grassland degradation not only alter terrestrial biogeochemical processes but also have strong potentials to affect nutrient stoichiometry and limitation in aquatic ecosystems. Moreover, the impacts of grassland degradation are likely to differentially affect the cycling of carbon (C), nitrogen (N), and phosphorus (P) in the linked terrestrial-aquatic ecosystems in watersheds, leading to multiple possible scenarios of nutrient stoichiometry and limitation in soil, stream, and lake ecosystems. However, we lack of integrated studies to consider biogeochemical consequences of grassland degradation transferring from soil to stream, and finally to the lake ecosystems. An integrated case study was conducted in the Qinghai Lake Watershed on the Qinghai-Tibet Plateau to reveal the influences of grassland degradation on soil, stream, and lake ecosystems from the perspectives of C:N:P stoichiometry , nutrient limitation, and bacterial communities. This case study demonstrated a clear cascading influence from terrestrial to aquatic ecosystem, that grassland degradation differentially influenced N and P in soil with soil N decreased but P did not change (N:P decreased in soil), influencing the nutrients delivered to streams with streamwater N decreased but P increased (N:P decreased in stream), alleviating P limitation of stream biofilms which are sensitive to P variation, and ultimately stimulating phytoplankton growth in the P-limited Qinghai Lake. This case study supported one scenario of biogeochemical consequences of grassland degradation, and other scenarios might be also possible in watersheds that have different geochemistry background, different landcover, and/or different lake trophic status. Integrated studies considering the coupled terrestrial-aquatic ecosystems can provide insights for protection and management of grassland watersheds in the rapidly changing world.

Understanding land use and land cover (LULC) change dynamics and their contributing factors are critical for developing sustainable land management strategies. Therefore, this paper assesses the trends and patterns of LULC changes and their drivers in the Migori River watershed in Kenya from 1980 to 2020. The spatial analysis is based on remote sensing data based on the maximum likelihood classifier algorithm; whereas the analysis of the drivers is based on index-based ranking and logistic regression of 318 households’ survey data. The results show that between 1980 and 2020, the watershed experienced a considerable decline in shrub lands by 40.63% (−235.97 km²), grasslands by 84.86% (−59.14 km²), forests by 52.90% (−98.36 km²), water by 82.03% (−39.27 km²) and wetlands by 38.44% (−3.69 km²); whereas cultivated land, bare land and built-up areas expanded over the same period by 34.25% (+347.42 km²), 132.28% (+60.95 km²) and 461.20% (+25.32 km²), respectively. The results of the household survey revealed that the perceptions of the locals tended to corroborate these observed LULC patterns obtained from spatial analysis, with 60.50% (n = 192) of the respondents reporting a significant expansion in agricultural land use (at p < 0.05), and 75.80% (n = 241) observing a significant decline in forest areas in the watershed (at p < 0.05). Fuel wood collection, timber/poles production, agricultural expansion, population pressure, and high poverty are the major drivers of these LULC changes. The findings also revealed that educational level significantly influenced the survey participants’ perceptions concerning these drivers. The paper concludes that the watershed’s natural landscapes have been undergoing destruction at the expense of human settlement and infrastructural developments driven by anthropogenic activities. Therefore, there is a need, among others, for land use zoning to regulate conflicting land uses on the watershed between settlement, conservation, and agricultural lands.

Extreme climate events, such as hurricanes and tropical storms, can cause acute instability of the hydrologic cycle, thereby threatening the sustainability and resiliency of an authentic watershed ecosystem’s services. A 2011 extreme climate event, known as Hurricane/Tropical Storm Irene (Irene), imposed an acute effect on the quality of the ecosystem services in Vermont. This risk assessment of the Otter Creek Basin (the Basin) watershed restoration in central Vermont included an analysis of the conceptual site model, key elements of the strategic plan, and potential ecological outcomes. The outcome of the ecological restoration of the Basin is dependent upon an adaptive management strategy, which is implemented through various regulatory policies. Thereby, a systematic literature review (SLR) of regulatory milestone documents released between 1998 and 2019 was completed to characterize and assess the Basin’s strategic planning efforts and forecasts. To operationalize this study, a replicable methodology was utilized by using a conceptual site model to assess and forecast data trends. Analysis of the data trends resulted in an ecological risk assessment of the 2019 tactical basin plan (TBP) that forecasted 2021–2025 restoration activities. Currently in a transition phase as a hybrid ecosystem while undergoing restoration activities, the Basin’s restoration strategy could result in the re-establishment of the watershed as an authentic ecosystem, which can self-regulate with appropriate biodiversity and ecosystem function based on past history. However, without restoration and resiliency, a poorly managed strategy could result in a decreased classification toward a novel, no-analogue ecosystem, where keystone species are lost and ecosystem functions are highly altered. Therefore, a successful restoration is essential to elevate the Basin from a hybrid ecosystem by restoring its authentic characteristics and regaining its self-regulated natural ecosystem services.

Globalization and industrialization lead to the corresponding increase of effluents discharged into the nearest water bodies. The persistence of pollution in the ecological system has led to uncertainty about living habitats; drinking water safety has become a societal issue attached to great importance. As we increasingly become aware of environmental problems and their impacts on human life, we realize that current problem-solving using contemporary water treatment techniques cannot provide adequate solutions owing to their advantages and disadvantages. Nature-based solutions are required as they are the best alternative for treating polluted water. Conventional coagulation is not a new technique that has been utilized in ancient times and works as a sustainable solution for water treatment and reduces the costs associated with the other treatment methods. Even though these techniques have been practised since ancient times, there is still a need to explore more plants to identify coagulating properties. The current study aims to do the phytochemical and physicochemical screening of the plant-based materials to identify them as coagulants and compare their efficiencies with the conventional inorganic and animal-based coagulants; out of 18 plant-based materials, Moringa oleifera, Manihot esculenta and Pisum Sativum removed turbidity up to 100% are subjected to the FTIR, XRD, and SEM to analyze the functionalized groups responsible for the polymer formation and identify the interaction between the coagulator's and suspended particles. The results showed that plant-based materials could be promising solutions for water quality challenges.

The effect of the 1/10 the application rates of either copper sulfate, temephos, glyphosate, or bifenthrin on some biochemical and genotoxic markers of the Egyptian toads, Sclerophrys regularis, exposed for 96 h under conditions similar to the real situation was investigated. The results illustrated that, brain acetylcholinesterase (AChE) was significantly inhibited following temephos treatment, while the enzyme activities markedly increased following either glyphosate or bifenthrin exposure. Liver glutathione-S-transferase (GST) activity was inhibited following either copper sulfate or bifenthrin, while the activity increased following glyphosate treatment. Also, the data illustrated that, The level of glutathione reduced (GSH) in liver and the activities of lactic dehydrogenase (LDH), transaminasaes (AST and ALT), and phosphatases (ACP and ALP) in liver and serum showed significant increases following all the treatments and bifenthrin was the potent one. Regarding the genotoxicity of the tested pesticides, the number of structural aberrations induced by the different treatments was enumerated in the present study. It was found that all the tested pesticides significantly increased either the frequency of abnormalities or the number of polychromatic erythrocytes (PCE) per 1000 cells (the frequency of micronucleus, MN) compared to the negative control, where bifenthrin and temephos were found to be more potent than cyclophosphamide (positive control) to induce these structural aberrations. According to the present results, the tested concentrations of the tested pesticides could lead to a collapse of cellular homeostasis and changes in the biochemical and genetic parameters in the Egyptian toads which can be considered as indicators of environmental pollution by pesticides.

Ecological processes and distribution of biodiversity within river floodplains are driven by the hydrological regime of the area. The relationship between fish abundance/diversity and surface water quality at four impact points of the Sashadanga oxbow lake was examined based on hydrological connectivity (distance of lake sections from parent channel; density of buffer vegetation and hydrological phases of seasons). Fish sample populations (n = 1440) belonging to 10 orders showed greater numerical abundance in the pre-and post-flooding phases. Oxbow sites proximal to the parent channel showed higher comprehensive pollution index (CPI), higher dominance and lower species evenness during the pre-monsoon (minor flooding) and vice versa during the monsoon and post-monsoon (greater flooding periods). Diversity descriptors using curve/asymptote based on Hill’s numbers indicate significant site-specific fish diversity within the oxbow lake at different seasons. Discriminant analysis revealed that change in temperature, turbidity and concentration of inorganic nitrogen were significant predictors in differentiating the quality of the different sites of the lake. Principal component analysis (PCA) revealed that the relative abundance of each species order across sites was significantly influenced by changes in seasons and physicochemical parameters, and showed a weak association with the density of buffer vegetation at sites. Depending on the distance of oxbow areas to the parent channel, the combination of periodic flooding, riparian buffer and lake morphology define the degree of hydrological connectivity which in turn affects the composition and abundance of fish communities at different points of the lake.

The Rhodamine 6G (Rh6G), a cationic dye is actively being used as a potentially tracing dye in the field of biotechnology for immunological studies. The peel powder of Litchi Chinensis was employed in native condition to explore the sorption properties at different experimental conditions like initial dye concentration, contact time, dosage of biosorbent, temperature and pH. The detailed characteristics of Litchi chinensis peel before and after adsorption were performed by using sophisticated instruments like SEM-EDX, FTIR, BET and XRD. From the adsorption studies it was observed that the equilibrium data followed Pseudo-second order rate kinetics and Freundlich isotherm. The Langmuir adsorption capacity (Q_o) was found to be 6.66 mg/g, and the adsorption process was spontaneous and exothermic in nature (based on ΔG, ΔH and ΔS values). All the laboratory experiments proven to be an evident for the Litchi chinensis peel as an efficient biosorbent for the removal of Rhodamine 6G in the liquid/solid phase system.