Projected Land Use Research Articles

Modeling impacts of projected land use and climate changes on the water balance in the Baro basin, Ethiopia

In terms of land use and climate, the world is changing at an unprecedented rate and these changes have a significant influence on our water resources. This study was conducted to examine the individual and combined potential impacts of land use and climate change on the water balance of the Baro basin in Ethiopia for the baseline period (1985–2002) and near-future period (2023–2040) using the Soil and Water Assessment Tool (SWAT). The plausible land use scenarios considering current (CUR), business as usual (BAU), and further expansion of altitudinal forest and watershed management practices (CON), as well as climate change scenarios from regional climate model outputs (RCMs) under two representative concentration pathways (RCP4.5 and RCP8.5) for the 2023–2040 time frame, were used as inputs to the models. The monthly calibrated and validated SWAT model produced an acceptable result, which was then used for water balance simulations. Findings show that forest decreased from 54.5% to 48.9% and 41.2% while agricultural land increased from 21.8% to 29.7% and 39.8% under the CUR and BAU land use change scenarios, respectively. The results from the ensemble mean showed an increase in maximum and minimum temperatures and a decrease in rainfall under the RCP4.5 and RCP8.5 climate change scenarios, which in turn resulted in an increase in evapotranspiration (ET) and a decrease in water availability. Climate change outweighed the impact of land-use change, thus indicating an increase in annual ET by up to 12% and a decrease of 42% in surface runoff (SURQ) under the RCP8.5 scenario. The BAU land use scenario projection triggers a respective increase of 18% in annual SURQ and reduction of ET by 2%. However, under the CON land use scenario, SURQ decreased by 24%. The study concluded that future land use and climate change will further challenge the basin's water supply capacity to meet the increased water demand. Understanding the changes in the basin's water balance is critical for mitigation and adaptation options. As a result, this study proposes restoration efforts and climate-resilient water management strategies that can increase the resilience of the river basin.

Anticipating plant translocation in land-use projects: a case study of Helianthemum marifolium

ABSTRACT In the context of a land development project, we carried out an experimental translocation before the proposal of mitigation hierarchy related to the project. By doing this early, we obtained results on the experimental translocation and thus better inform the measure proposed as part of the project. This project is likely to impact a large population of the plant species Helianthemum marifolium, which has a national protected status in France. We present here the pre-translocation phase, proposing different methodologies to better understand and prepare for a translocation. First, we studied the potential future distribution based on climate factors. Then, we sought to improve our knowledge of the local populations studied. To do this, we carried out pollinator surveys and a study of reproductive success. Finally, we presented the results of germination and cultivation tests, which enabled us to determine the mechanism for breaking dormancy and the most favourable substrate for growing, and we compared potential host sites regarding soil analyses. These different aspects allowed us to determine a protocol to be followed for a more significant translocation of this species. This case study illustrates requirements of the pre-translocation planning and can be used to inform future translocations of Helianthemum marifolium. The case study also presents methods other translocation practitioners can use to improve their protocols in the future.

Genetic viability and habitat suitability of the critically endangered southern muriqui (Brachyteles arachnoides) in the Atlantic Forest's fragmented landscapes under land use and climate change scenarios

The joint effects of climate change and landscape fragmentation to the genetic viability of isolated populations has barely been addressed for the Atlantic Forest fauna. Therefore, this work explored the potential habitat suitability for the southern muriqui (Brachyteles arachnoides), by modeling climate change, landscape fragmentation, and genetic diversity loss of the species. Maxent was used to model its potential distribution in 2050, with two climate change scenarios. A land use and land cover change model was applied to describe current and future forest fragmentation patterns, and a Population and Habitat Viability Analysis (PHVA) was used to describe the retention of genetic diversity of the southern muriqui. Although PHVA modeling provided a low risk of extinction of the southern muriqui, climate change and fragmentation could result in the loss of >65% of the suitable forest patches, and reduce the habitat suitability to only 11% of the potential distribution area, which could lead to future genetic diversity loss and decreased capacity of self-sustained populations. In both climate change scenarios, the suitable areas for the southern muriqui in Paraná and Rio de Janeiro states will decrease more drastically. Areas where the primate occurs in the interior of São Paulo and Rio de Janeiro states will disappear or be climatically disconnected from the core potential habitat. Alike preventing further deforestation, Atlantic Forest restoration actions are needed to connect the viable populations for compensating the projected land use and climate change impacts to the long term persistence of the southern muriqui.

Park Design Informed by Stated Preference Choice: Integrating User Perspectives into the Development of an Off-Road Vehicle Park in Michigan

At a time when many public park and recreational programs are required by local governments to be financially self-sustaining, it is critical for planners to design a new development with the end-user in mind. Feasibility studies often either do not examine user preferences or use Likert-type surveys to investigate features in isolation without evaluating trade-offs from financial and finite space limitations. This study used stated preference choice method (SPCM) to inform the initial design of an off-road vehicle (ORV) park. The park was developed near Detroit, Michigan, a metropolitan area with many registered ORVs, but few places to legally use them. The SPCM examined trade-offs among desired features and helped planners ensure publicly funded investments resulted in a successful park. Researchers mailed a survey with choice sets to 3935 registered ORV users and 2083 completed surveys were retuned (53%). Additional survey items also allowed researchers to create preference models for specific segments of users (i.e., serious ORV enthusiasts/casual users; residents/visitors; or users of different ORV types). The findings informed the design of the park by revealing preferences for segments, allowing planners to design the park for specific markets. The park’s initial success suggests a study in the design stage of development offers utility, though park managers have noticed unanticipated user segments that influence preferences for park features. The findings based on segments also suggest planners should be cautious when designing to an average user. Implications of this study are helpful to planners of any capital-intensive land-use project, especially in the public sector.

Rescaling the land rush? Global political ecologies of land use and cover change in key scenario archetypes for achieving the 1.5 °C Paris agreement target

ABSTRACT Advancing future-oriented perspectives in political ecology and critical agrarian studies, this paper examines projected land use and land cover change (LULCC) dynamics in four ‘archetypal’ scenarios foregrounded by the IPCC for limiting global warming to 1.5°C by 2100. Focusing on the Global South, we explore how these archetypes project a radical reversal of historical LULCC and rural population trends, potentially implying a considerable rescaling of contemporary land rush dynamics. Taken together, land-based climate mitigation futures highlight risks related to the (re)production of relative surplus populations through processes of rural enclosure and accumulation by dispossession in the Global South.

Modelling Climate Change Impacts on Location Suitability and Spatial Footprint of Apple and Kiwifruit

The threats and opportunities faced by primary production industries from future climate changes can be adequately prepared for only with the guidance of model projections that can assist the development of robust policy and climate adaptation plans by governments and industries. We used continuous suitability models capable of reflecting incremental changes to project the suitability of locations across New Zealand for cultivating apple and kiwifruit in the mid- and late-century. These projections used future weather data from climate model simulations for two contrasting greenhouse gas (GHG) pathways: stringent GHG mitigation and unabated GHG emissions. To improve the suitability of the modelled temperature data, specifically for use with biologically driven, crop suitability models, we developed new bias-variance adjustments that preserved climate change signals within the data. Preliminary projections of land use across a range of alternative primary industries were obtained from a multinomial logit model incorporating continuous suitability scores as predictors. We refined the preliminary land-use projections by providing them as inputs into a simulation model of land use incorporating other drivers and constraints. This methodology provides a means for projecting future land use and the spatial footprints of primary industries, based on biological and econometric considerations, under different modelled climate change scenarios.

Assessing the impacts of human disturbance on ecosystem services under multiple scenarios in karst areas of China: Insight from ecological conservation red lines effectiveness

Exploring the impacts of human disturbance on ecosystem services (ESs) in karst areas is crucial for regional sustainable management, and China’s ecological conservation red lines (ECRLs) could provide innovative solutions for global biodiversity conservation. However, it remains unclear how the implementation of ECRLs policies will change the mechanism of human disturbance on ESs. Based on the Conversion of Land Use and its Effects at Small Region Extent (CLUE-S) model, we projected land use changes in 2035 under a Business as Usual (BAU) scenario, Ecological Protection (ELP) scenario, and Future City Plan (FCP) scenario in Weining County, China. The Integrated Valuation of Ecosystem Services and Trade-off (InVEST) model was used to quantify six ESs—crop production, water yield, soil conservation, carbon storage, nitrogen export, habitat quality—and total ecosystem services (TES). Then, we analyzed the impacts of human disturbance changes on ESs. Our research showed that under the ELP scenario, the human disturbance index would decrease by 6.18% and increase in soil conservation (0.34%), carbon storage (21.27%), and habitat quality (9.14%) compared with 2015. A greater area of forest and grassland would lead to a reduction in cropland area, which would lower crop production by 20.76%, with water yield and nitrogen export decreasing by 6.63% and 19.91%, respectively, from 2015 to 2035. The ELP scenario would lessen trade-offs between water yield and carbon storage and habitat quality, such that water yield and nitrogen export would be similar. Meanwhile, to ensure future crop production, more attention should be given to the increase in water yield and nitrogen export caused by cropland expansion, especially in its non-karst areas. TES would increase by 9.27%, which is higher than that obtained under either the BAU or FCP scenario. Eco-environmental conservation and restoration policies were proposed to help its regional high-quality development. Our research provides a decision-making basis to evaluate the implementation effects of ECRLs policies in karst areas and inform the directed management of ecosystems by the government.

Effect of urbanization on the dynamics of ecosystem services: An analysis for decision making in Kolkata urban agglomeration

Urbanization has profound influence on the changes of land use and land cover, which on the other hand exert significant impact on ecosystem services and their values, especially in the urban agglomerations. Kolkata urban agglomeration of India has been selected to determine the causes in changes of ecosystem services under present and projected land use land cover scenario. Land use land cover maps of 1990, 2000, 2010 and 2020 were prepared by support vector machine method, using LANDSAT satellite imageries and projected up-to 2040 using CA–Markov model. Built-up land was increased by 65.39% during 1990–2020 and will further increase to 76.88% by 2040. Built-up lands are mainly encroaching crop lands and wetlands. During the period of fifty years (1990–2040), the ecosystem service value will decrease from $38,486.49 to $28,060.79, with annual rate of decrement of 0.54%. During the same period, the spatial extent of very low ecosystem service value will be increased from 16.60 to 58.88%; whereas, the area coverage of very high ecosystem service value will be decreased from 2.69 to 2.35%. Water supply contributed highest ecosystem service value followed by disturbance regulation and nutrient cycling; whereas, lacking in soil formation, pollination and biological control services contributed lowest. The study will help in decision making process for sustainable management of natural resources and also provide useful guideline for the quality improvement in urban ecosystems.

Coastal Flood Modeling to Explore Adaptive Coastal Management Scenarios and Land-Use Changes Under Sea Level Rise

In a Climate Change (CC) context, low-lying areas like marshes are more vulnerable to Sea Level Rise (SLR) or extreme climate events leading to coastal flooding. The main objective of this study is to help local stakeholders determine the best coastal management strategy for the Moëze marsh (France) that can contribute to adapt to SLR in this zone. To do so, we used the MARS hydrodynamic model to simulate coastal overflowing in the zone for different scenarios. We first calibrated the model based on data from the Xynthia storm which occurred on February 28th 2010. Our focus is on modeling the high astronomical tide-induced flooding, taking into account regional SLR projections by 2030 and 2050 under the pessimistic RCP 8.5 CC scenario. Several Coastal management configurations proposed by local decision-makers, as well as different land-use projections were considered. The results highlight that the implementation of closed defenses around human and economic stakes do not lead to significant reductions in flooding (surface extent and maximum water height) compared to the case where the sea-dikes are no longer maintained and the coastline is unconstrained. This can be explained by the fact that these stake zones were historically built on higher points of the marsh. We have also shown that land-use changes have an influence on flooding in the Moëze marsh, especially an increase greater than 0.25 m in the maximum simulated height when considering a new land-use by 2030. The increase is less pronounced (under 0.25 m) when considering a new land-use by 2050. These results do not take into account the possible future evolution of the topography due, for example, to the presence of new habitats that would trap the sediments.

African heritage challenges: Communities and sustainable development

For many people, the term ‘heritage’ is associated with ontologies and cultures based on specific localities. With globalization, however, heritage became internationalized. Even World Heritage Sites (WHSs) connote a universalist, globalization-based ethos that relegated ‘site’ to an adjunct word. The current zeitgeist of globalization acts out in the dynamics post-colonialism, environmentalism, and infrastructural and land-use projects that reflect its focus on markets and development. As a result, heritage becomes blurred, diluted, and less attributable. The prevailing idea is that ‘legacies belong to the past’. Today’s world sees heritage as a resource and to achieve the development of certain sectors like tourism. African heritage challenges: Communities and sustainable development looks at this issue in the context of Africa, including its urban areas. The book notes that Africa’s growing cities are increasingly resistant to the forces of globalization. The book’s interdisciplinary approach, as well as its inclusion of African scholars, makes it a valuable resource. The book’s inclusion of African scholars is a welcome shift from older works that cast a Western gaze on the continent.

Evaluating potential impacts of land use changes on water supply–demand under multiple development scenarios in dryland region

Water scarcity greatly hinders sustainable development goal agenda and regional agriculture development in dryland regions. As we know, land use and cover changes are strongly responsible for spatial–temporal evolutions of water resource. However, there is little explicit understanding of how spatial patterns of future dryland use will affect the water supply–demand risk. To answer this question, this study took Yulin city of China, a typical dryland region, as a case study area, and firstly estimated its 2020–2050 land use patterns under three different scenarios, covering Natural Increased Scenario (NIS), Food Security Scenario (FSS) and Economic Development Scenario (EDS), with the help of the path-generating land use simulation (PLUS) model as well as Markov-chain model. Furthermore, this study employed InVEST model to explicitly investigate spatial–temporal evolutions of water supply, water demand and water supply–demand risk in all scenarios. The estimated results indicated that the largest expanding/shrinking land use types were grasslands/croplands in NIS, croplands/grasslands in FSS and built-up lands/croplands in EDS during 2020–2050, respectively. By 2050, all projected land use changes only slightly affected regional water supply (the fluctuation of ∼ 5% compared to that in 2020), but greatly increased by ∼ 57% regional water demand. Particularly, strong land use changes would likely put nearly 90% regions of Yulin city at endangered water supply–demand risk in 2020–2050. Ecological land and built-up land would easier suffer from critically endangered water supply–demand risk. In view of these modeled and analyzed results, some potential mitigation strategies of water resource utilization, such as developing water-efficient eco-agriculture, adjusting agricultural structures and enriching revegetation diversity, were suggested to coordinate future areal human-nature relationships. This study could provide some valuable information for dryland agricultural development, water-environment management and regional policy decision-making.

Projected land use change in an oil-rich landscape in Uganda: A participatory modelling approach

The discovery of oil in the North Albertine Rift Landscape of Uganda has increased pressure on land and heightened the potential for resource use conflict. In this article, we focus on changing land use dynamics as oil extraction unfolds in a new resource frontier. We ask how the development of the nascent oil industry will affect land use dynamics, including land use conflicts. This leads us to identify the land use change already arising and to use this as the basis for participatory modelling of projected change. Given they are dominant forms of land use, agriculture and forestry are central to our analysis. Design of the methodology combined remote sensing with innovative modelling incorporating participatory development methods. This facilitated insight into projected land use patterns, and specifically relationships between small-scale food production, commercial sugarcane production, and forestry conservation adjacent to settlement areas. Our data show that ill–defined land boundaries and an aggressive sugarcane out-grower scheme are avenues for so-called land grabbing. Modelling scenarios under both the status quo and under oil extraction suggest the land area covered by sugarcane production will increase at the expense of food crop farming. Given a context where forestry conservation is an important form of land use, we also consider the implications of local agricultural change on land reserved for conservation. Overall, our modelling indicates that in accounting for land use change within the resource frontier associated with oil extraction, there needs to be insight into the intricate interconnections between different forms of rural land use as future change unfolds. Understanding how oil extraction effects rural land use patterns holds relevance for planning in contexts of the Global South where new oil industries are emerging. Innovative methodologies for teasing out these complex land use dynamics can aid planning that seeks to anticipate and reduce land use conflict and support agricultural livelihoods.

Land evaluation for land use planning in Sambhunath municipality of Saptari district, Nepal

Dynamics of land use are closely related with society, development activities and environment. For the sustainable management of land resource of an area, land use may act as one of the elements of conflicts which could be resolved through land use planning ensuring equitable access and right of land to the owners. The present paper attempts to assess the land use for land use planning and infrastructure development through land evaluation including risk factors. Sambhunath municipality located within Saptari district of Nepal has been used as the study area to test the issues raised. Both qualitative and quantitative methods are used for data generation and analysis. Land use changes have been analyzed for the period 1986 to 2017. Potential land use zones have been identified through land suitability analysis using MCE-AHP and in relation to the risk factors such as flood, soil erosion, landslide, and fire. The infrastructure development plan has been allocated based on land use suitability index maps and planning guidelines. Land use projection have been made through Cellular Automata technique, and land use plans have been developed based on projected land use and optimized through SWOT analysis. Implementation strategy is developed based on legal framework to implement land use plan at local level. The land use change patterns are characterized by the increase of agriculture and built-up area and the decrease in areas under forest cover and water body simultaneously. Altogether 27 different criteria are identified and applied in land use suitability evaluation. Risk prone area is found mostly surrounding to the foot of Chure hill and along Khando river. Almost 46% of the total areas have been planned for future agriculture land use followed by residential, commercial, industrial and public uses which are 201 ha, 26 ha, 3ha, and 345 ha respectively. An implementation strategy has been devised to empower and enforcement for compliance of land use zone together with guidelines for outlined development activities.

Modeling Impacts of Projected Land Use and Climate Changes on the Water Balance in the Baro Basin, Ethiopia

Modeling Impacts of Projected Land Use and Climate Changes on the Water Balance in the Baro Basin, Ethiopia

Study on Evaluation of Rational Land-Use Based on EES Model of Supply and Demand Equilibrium

The function value of land ecological services is underestimated, which leads to over-exploitation. There is an urgent need to establish a comprehensive evaluation model that can reflect the real cost of land-use projects. In this paper, we establish an EES model based on the equilibrium of supply and demand under the fixed supply of natural resources. In this model, the target value is mainly composed of ecological value EC_1 and economic value EC_2 of land ecosystem services. Subjective value is affected by different social preferences, the relationship between human development index and social value SC is established through the Pearl Growth Model, and the share of subjective value in total land value under different levels of social development is calculated. Finally, according to the utility value theory, the land scarcity index SI is introduced to reflect the relationship between land demand and land stock of land-use projects in the region and shows that the land price per unit area of different scales is different.

Balance of sugarcane plantation land needs in Lamongan Regency in 2031 based on land-use changes using SPOT imagery

The volume of Indonesia's sugar imports in 2019 reached 4,09 million tons. The high volume of imports was influenced by the decreasing area of sugarcane plantations. Lamongan Regency is one of the sugarcane and sugar-producing regencies in East Java. Sugarcane and sugar production in Lamongan Regency has experienced quite diverse dynamics and has been influenced by changes in land-use conditions. This study aims to analyze the balance of land needs for sugarcane plantations in Lamongan Regency in 2031 based on an analysis of land-use changes using SPOT imagery of 2007, 2013, and 2019. The study was conducted by analyzing land-use changes, population projections, and land demand balance analysis for sugarcane plantations. The results of the analysis showed that the population of Lamongan Regency in 2031 is projected to reach 1.419.843 people with a land requirement for sugarcane plantations of 2.362,29 ha. There will be a land surplus of 1.276,92 ha but it is still concentrated in 7 of the 27 sub-districts. Sugarcane plantations in Lamongan Regency have the potential to be developed considering that the land allocation for plantations in the Lamongan Regency Spatial Plan of 2011-2031 reaches 10.022,42 ha.

How will the progressive global increase of arid areas affect population and land-use in the 21st century?

One of the possible consequences of projected global warming is the progressive enlargement of drylands. This study investigates to what extent population and land-use (forests, pastures, and croplands) are likely to be in areas turning arid in the 21st century. The first part of the study focuses on the climatological enlargement of arid areas at global, macro-regional, and high-resolution (0.44°) scales. To do so we analysed a large ensemble of CORDEX climate simulations, combined three indicators (FAO-UNEP aridity index, Köppen-Geiger climate classification, and Holdridge life zones), and quantified the areas turning from climatologically not arid into climatologically arid (and vice-versa) from recent past (1981–2010) to four projected global warming levels (GWLs) from 1.5°C to 4°C. In the second part, we used population and land-use projections to analyze their exposure to progressive shifts to drier or wetter climate. Both types of projections follow five socio-economic scenarios (SSPs from SSP1 to SSP5). We present results for the viable combinations between SSPs and GWLs. Depending on GWL, the projected drying patterns show regional differences but, overall, the negative consequences of climate change are clear. Already at 1.5°C warming, approximately 2 million km2 (1.4% of global land) are likely to become arid; at 2°C this area corresponds to 2.6 million km2 (2.7%), at 3°C to 5.2 million km2 (3.5%), and at 4°C to 6.8 million km2 (4.5%), an area that can be ranked the seventh largest country in the World. Such drying is particular strong over South America and southern Europe. In the worst-case scenario (SSP3, regional rivalry, at 4°C), approximately 500 million people will live in areas shifting towards arid climate. Forest areas are likely to be more affected in South America, pastures in Africa, and croplands in the Northern Hemisphere. For land-use, the worst-case scenarios are SSP3 and SSP5 (fossil-fuel based future): at GWL 4°C, about 0.5 million km2 of forests and 1.2 million km2 of both pastures and croplands are likely to be in areas shifting to arid climate.

Phytoplankton and cyanobacteria abundances in mid-21st century lakes depend strongly on future land use and climate projections.

Land use and climate change are anticipated to affect phytoplankton of lakes worldwide. The effects will depend on the magnitude of projected land use and climate changes and lake sensitivity to these factors. We used random forests fit with long-term (1971-2016) phytoplankton and cyanobacteria abundance time series, climate observations (1971-2016), and upstream catchment land use (global Clumondo models for the year 2000) data from 14 European and 15North American lakes basins. We projected future phytoplankton and cyanobacteria abundance in the 29 focal lake basins and 1567lakes across focal regions based on three land use (sustainability, middle of the road, and regional rivalry) and two climate (RCP 2.6 and 8.5) scenarios to mid-21st century. On average, lakes are expected to have higher phytoplankton and cyanobacteria due to increases in both urban land use and temperature, and decreases in forest habitat. However, the relative importance of land use and climate effects varied substantially among regions and lakes. Accounting for land use and climate changes in a combined way based on extensive data allowed us to identify urbanization as the major driver of phytoplankton development in lakes located in urban areas, and climate as major driver in lakes located in remote areas where past and future land use changes were minimal. For approximately one-third of the studied lakes, both drivers were relatively important. The results of this large scale study suggest the best approaches for mitigating the effects of human activity on lake phytoplankton and cyanobacteria will depend strongly on lake sensitivity to long-term change and the magnitude of projected land use and climate changes at a given location. Our quantitative analyses suggest local management measures should focus on retaining nutrients in urban landscapes to prevent nutrient pollution from exacerbating ongoing changes to lake ecosystems from climate change.

Combined effects of predicted climate and land use changes on future hydrological droughts in the Luanhe River basin, China

Both climate and land-use changes can influence drought in different ways. Thus, to predict future drought conditions, hydrological simulations, as an ideal means, can be used to account for both projected climate change and projected land-use change. In this study, projected climate and land-use changes were integrated with the Soil and Water Assessment Tool (SWAT) model to estimate the combined impact of climate and land-use projections on hydrological droughts in the Lutheran River basin. We showed that the measured runoff and the remote sensing inversion of soil water content were simultaneously used to validate the model to ensure the reliability of the model parameters. Following calibration and validation, the SWAT model was forced with downscaled precipitation and temperature outputs from a suite of nine global climate models (GCMs) based on CMIP5, corresponding to three different representative concentration pathways (RCP2.6, RCP4.5 and RCP8.5) for three distinct time periods: 2011–2040, 2041–2070 and 2071–2100, referred to as early century, mid-century and late-century, respectively, and the land use predicted by the CA–Markov model in the same future periods. Hydrological droughts were quantified using the standardized runoff index (SRI). Compared to the baseline scenario (1961–1990), mild drought occurred more frequently during the next three periods (except for the 2080s under the RCP2.6 emissions scenario). Under the RCP8.5 emissions scenario, the probability of severe drought or above occurring in the 2080s increased, the duration was prolonged, and the severity increased. Under the RCP2.6 scenario, the upper central region of the Luanhe River in the 2020s and upper reaches of the Luanhe River in the 2080s were more likely to experience extreme drought events. Under the RCP8.5 scenario, the middle and lower Luanhe River in the 2080s was more likely to experience these conditions.Graphic abstract

GIS-Based Projected Land Use: A Case Study of Dhanbad District, Jharkhand, India

In the present investigation, a comparative study on acute toxicity of mercury to air breathing fish, Channa gachua (Ham.) and nonair breathing fish, Cyprinus carpio (Linn.) was undertaken. The 96h median lethal concentration (LC50) for C. gachua (0.188 mg l-1) was higher than that of C. carpio (0.105 mg l-1). From the result, the non-air breathing fish, C. carpio was 1.79 times more susceptible than C. gachua to mercury toxicity. Both the fishes showed changes in their ethological responses with the progress of time of exposure and increasing concentration of the toxicant. An alteration in the haematological parameters also recorded when the fishes exposed to mercury stress. The haemoglobin content (Hb), total erythrocyte count (TEC) and haematocrit (Hct) for both fishes significantly reduced) during their acute exposure. The level of total protein and serum globulin significantly decreased) at 96h in both fishes compared to the initial exposure at 0h, whereas, total glucose, triglyceride, cholesterol and albumin increased significantly in both fishes at 96h. The degree of change for each parameter was similar in both the fishes. This comparative study may help to determine the degree of toxicity of mercury as well as to understand its mode of action in the light of ethological and haematological responses to the fishes belong to different physiological nature.