Water Habitat Research Articles

Ecological Monitoring and Assessment of Freshwater Ecosystems: New Trends and Future Challenges

Freshwater ecosystems, particularly rivers and lakes, are under severe pressure due to increasing anthropogenic activities, such as water extraction, flow regulation, pollution, and habitat fragmentation [...]

Diversity of mosquito natural enemies and their feeding efficacy on Aedes vectors.

Mosquito-borne diseases are a major health issue among communities in Asia, and dengue has grown up as a serious public health concern in Sri Lanka with varying magnitude since 1960. With the realization of the failures and limitations of current vector control strategies, the authorities are moving towards simple, low-cost, and eco-friendly vector management methods. Thus, the present study was devised to evaluate the potential densities of mosquito natural enemies in natural water habitats in Galle district, Sri Lanka, and to investigate the feeding efficacy of prominent mosquito natural enemies on main dengue vectors (Aedes sp.) in a laboratory setting. The survey was carried out using eight sentinel sites in Galle district, and samples of mosquito natural enemies and mosquito larvae were collected, and then they were identified using taxonomic keys. Study records, the aquatic insects of Family Hydrometridae, Belostomatidae, Notonectidae, Nepidae, Ranatridae, and Corixidae as dominant mosquito natural enemies, and Libellulidae and Dytiscidae insects as sub-dominant families. The highest density of the family Hydrometridae was recorded in rural, natural inland, and rocky study sites. The order Hemiptera was recorded as the key order of the mosquitoes natural enemies in Galle district. The family Hydrometridae had the highest density of recorded mosquito natural enemies. Aedes aegypti and Ae. albopictus were recorded as abundant vector mosquitoes. Family Nepidae is the most effective natural mosquito predator on Ae. aegypti and Ae. albopictus, and this knowledge will be vital for implementing future biological control strategies for Aedes vectors in Sri Lanka.

Ecological Security Pattern Construction in Loess Plateau Areas—A Case Study of Shanxi Province, China

Strong soil erosion and increasing human activities have made Loess Plateau areas ecologically fragile regions. Constructing the ecological security pattern (ESP) is imperative to maintain their ecosystem functions and sustainable development. However, it is still challenging to establish the ESP in such an unstable and scattered ecological environment. In this study, we take Shanxi Province, which suffers severe ecological problems in Loess Plateau areas, as an example to construct the ESP in a pattern of “source-resistance-corridor”. The proposed methods include the following steps: (1) potential ecological sources are selected with important ecosystem functions based on contributions of soil and water conservation, habitat quality, and carbon storage; (2) ecological sources are determined by considering core areas at the landscape scale based on morphological spatial pattern analysis (MSPA) along with stability based on dynamic assessment on previous sources; (3) the comprehensive resistance surface is constructed by multiple resistance factors and remotely sensed nighttime light data; (4) ecological corridors are simulated and extracted based on circuit theory. As a result, the proposed ESP in our study area mainly includes 13,592 km2 of ecological sources, 8519.64 km of ecological corridors, and 277 ecological nodes. Meanwhile, an ecological framework of “two axes, three belts, and three zones” was proposed based on the optimization and reorganization of ecological components within the ESP. Our research lays a methodological and practical foundation for regional ESP construction and sustainable development in Loess Plateau areas.

Amphistome Infection and Species Diversity of Freshwater Snails Collected from Selected Wildlife Drinking Water Sources in Matebeleland Region of Zimbabwe.

This study aimed at determining the identity of freshwater snails collected from selected water habitats frequented by wildlife as source of drinking water in the Matebeleland region of Zimbabwe and further screening the identified snails for natural infections with amphistomes using PCR. A total of 487 freshwater snails were collected from six areas in the Matebeleland region of Zimbabwe for identification and screening of amphistome infection. Eight freshwater snail species were morphologically identified and Biomphalaria pfeifferi, Bul. tropicus, Bul. truncatus, Bul. globosus, and L. (R.) natalensis were confirmed using the COI gene. Bulinus tropicus and Phy. acuta were the most abundant species at 33.9% (165/487) and 31.2% (155/487), respectively. DNA of amphistome was detected in 11.9% (58/487) of the collected snails. The highest infection rate was detected in Bul. globosus (44.4%). West Nicholson recorded the highest infection rate (33.9%), and infection was not detected in L. (R.) natalensis, Phy. acuta, and Bellamya spp. Amphistome DNA from M. tuberculata was successfully sequenced and identified as Calicophoron microbothrium. An additional band was detected in M. tuberculata, Bul. tropicus, and Bul. trancatus, which showed a 96.42% similarity to Paragonimus sp. sequence in the GenBank.

An assessment of the water footprint of the population and agricultural crops in the natura 2000 site ROSCI0434 siretul mijlociu, Romania

The designation of a Natura 2000 site ROSCI0434 Siretul Mijlociu for the protection of habitats and species, whose development is closely tied to the aquatic environment, signifies that the management of water resources, and implicitly, the water footprint, has contributed to maintaining a balanced and favorable status for biodiversity conservation. Given that the Natura 2000 site was declared based on older studies, and the Management Plan for the protected natural area was not yet developed, we are now conducting an assessment of the impact of the water footprint in the current climatic conditions. This includes considering other predominant types of agricultural crops and changes in food habits. This evaluation aims to understand the relationship between the water footprint and the conservation status of species and habitats in light of these new circumstances.The blue and grey water components of the water footprint are the ones that directly affect the natural protected area out of the three components of the water footprint: green, blue, and grey water. The ecological impact of water use in ROSCI0434 Siretul Mijlociu is extensive, affecting both terrestrial and aquatic ecosystems. Pollutants can harm habitats and species, while agricultural water usage alters habitats and disrupts hydrological patterns, impacting breeding and foraging grounds. Additionally, changes in water quantity and quality diminish ecosystem services like water purification and habitat provision, affecting biodiversity and human well-being.

The Effects of Wetland Degradation on Ecological Species

Wetlands are vital ecosystems that provide numerous ecological services, including flood control, water filtration, carbon sequestration, and habitat for diverse flora and fauna. However, human activities such as urbanization, agriculture, and infrastructure development have led to widespread wetland degradation worldwide. Wetland ecosystems diminished by 21-35% between 1700 and 2020 as a result of human interference, with at least 1.3 million square miles of wetlands lost globally—an area about the size of Alaska, Texas, California, Montana, New Mexico, and Arizona combined. This research used a documented methodology for extracting information from different books, conversations, conferences, and international organizations to understand the effects of wetland degradation on the decline of species and strategies for wetland conservation and restoration. This paper aims to elucidate the multifaceted effects of wetland degradation on ecological species. The results indicate that wetland degradation declines water quality, leading to alterations in water flow patterns, decreased groundwater recharge, and increased flooding downstream. This can result in the loss of biodiversity, as many species depend on specific water levels and habitats within wetlands. Moreover, the loss of wetlands diminishes their volume to store carbon, contributing to greenhouse gas emissions and exacerbating climate change. Furthermore, wetland degradation compromises water quality by reducing the natural filtration and purification functions of wetlands. Contaminants from agricultural runoff, industrial discharge, and urban pollution accumulate in degraded wetlands, posing risks to human health and aquatic ecosystems. Additionally, the loss of wetlands exacerbates erosion and sedimentation, leading to habitat destruction and loss of coastal resilience against storms and sealevel rise. Addressing wetland degradation requires a multifaceted approach, including policy interventions, restoration efforts, and public awareness campaigns. Effective wetland conservation strategies involve the preservation of existing wetlands, restoration of degraded ones, and sustainable management practices to mitigate further degradation. Collaborative efforts between governments, NGOs, local communities, and stakeholders are essential to safeguarding these critical ecosystems and the invaluable services they provide to the environment and society.

Living Shoreline Ecosystem Service Valuation Tool

Living shorelines are an increasingly popular way to protect and stabilize waterfronts for coastal property owners. Living shorelines provide valuable benefits to humans, including water quality improvement, habitat, fisheries, and carbon sequestration. Estimating the economic value of the ecosystem services living shorelines offer is an integral part of management decisions. The living shoreline valuation tool can help quantify the costs and benefits of living shorelines projects. This publication briefly describes the ecosystem services associated with living shorelines. The purpose of this publication is to introduce the ecosystem service valuation tool. Our target audience for the living shoreline evaluation tool includes natural resource extension agents, community organizations, and coastal homeowners who want to calculate the value of ecosystem services provided by coastal restoration projects, including living shorelines.

Environmental DNA Reveals Geographic Distributions of Two eel Species, Anguilla japonica and A. marmorata, in Western Kyushu, Japan.

Some anguillid eels migrate thousands of kilometers from their spawning grounds, dispersing across vast geographic areas to fresh and brackish water habitats, where they settle and grow. Japanese eels (Anguilla japonica) and giant mottled eels (A. marmorata) are both found in Japan, although their distributions differ, and their exact distributions are poorly known. We assumed that topographic distribution patterns of Japanese and giant mottled eels must differ among and within rivers along the northwest coast of Kyushu, Japan. Environmental DNA (eDNA) analysis was conducted at 87 sites in 23 rivers. Japanese eel eDNA was detected in 19 rivers (82.6%) and that of giant mottled eels was detected in eight (34.8%). We detected giant mottled eel eDNA in five rivers where they were previously unknown. eDNA for Japanese eels was detected at six of nine sites in the north (66.7%), 13 of 23 sites in Omura (56.5%), and 37 of 55 sites in the south (67.3%). In contrast, giant mottled eel eDNA was detected at one of nine sites in the north (11.1%), no sites in Omura, and 15 of 55 sites in the south (27.3%). There was no correlation between eDNA concentrations of the two species at 10 sites in the five rivers where eDNA of both species was detected. These findings suggest differences in the distribution of the two eel species and the northern distributional limit of giant mottled eels in the area facing the East China Sea.

Pontederia crassipes Biosynthesised Silver Nanoparticles (AgNPs), Characterisation and Activity against Multidrug-Resistant Microbes

Introduction: Pontederia crassipes (water hyacinth) has been singled out as one of the major causes of enormous economic and ecological losses to tropical water systems and habitats. Almost impossible to eradicate, the ominous species is characterized by rapid multiplication, giving rapid and extensive spread that can choke entire rivers and water bodies. However, vast, diverse bioactive secondary metabolites are found in P crassipes which exhibit an expansive assortment of antibacterial properties used in traditional medicine. The rapid emergence of Multi Drug Resistant (MDR) pathogens to common drugs is a pandemic of global proportions. Global health institutions are calling for a coordinated, global action plan to develop new biomaterials to combat the rising threat by MDR strains and improve treatment outcomes and save lives. This study proposes consumption of the water hyacinth lily species through a novel, material biosynthesis approach not only to manage the aquatic infestation but to develop advanced multifunctional, anti-microbial Silver nanoparticles through bio-reduction and capping of Silver salts targeted at MDR microbes. Methodology: After screening for active phytoconstituents of P.crassipes. The Biosynthesis of Novel AgNPs mediated by phenolic, antibacterial lyophilized hydro-ethanolic extracts from P crassipes as both bioreduction and capping agents was investigated. The resultant AgNPs characteristics, toxicological profiles and the antibacterial effects on 10 common microbes including MDR bacterial strains were evaluated. Observations and Results: TEM revealed that cubic and spherical nanometric AgNPs structures were successfully synthesized with particle size range from 10-60nm. With an average zone of inhibition of 29mm and an MIC of 6.25 µg/ml .The nanoparticles were efficacious against selected MDR strains and common infectious bacterial strains tested. In-vivo acute oral toxicity evaluations confirmed the safety of P crassipes. Conclusion: Biogenic P.crassipes mediated AgNPs are feasible, safe and efficacious and have immense potential for optimization into efficient broad spectrum MDR antibacterial agents.b

Flexible migration and habitat use strategies of an endangered waterbird during hydrological drought

AbstractWildlife species confront threats from climate and land use change, exacerbating the influence of extreme climatic events on populations and biodiversity. Migratory waterbirds are especially vulnerable to hydrological drought via reduced availability of surface water habitats. We assessed how whooping cranes (Grus americana) modified habitat use and migration strategies during drought to evaluate their resilience to changing conditions and adaptive capacity. We categorized >8000 night‐roost sites used by 146 cranes from 2010 to 2022 and examined relative use during non‐drought, moderate drought, and extreme drought conditions. We found cultivated and uncultivated palustrine and lacustrine wetlands were generally used less during droughts than non‐drought conditions. Conversely, impounded palustrine and lacustrine systems and rivers served more frequently as drought refugia (i.e., used more during drought than non‐drought conditions). Night roosts occurred primarily on private lands (86% overall); public land use decreased with latitude and increased with drought severity, with greatest use (56%) occurring during severe autumn drought in the southern Great Plains. Quantifying use of identified critical habitats in the United States indicated that Cheyenne Bottoms State Waterfowl Management Area and Quivira National Wildlife Refuge were used less during drought, and the Central Platte River and Salt Plains National Wildlife Refuge received similar use during drought compared to non‐drought conditions. Our findings provide insights into compensatory use of habitats, where impounded surface water may function in a complementary fashion with natural wetlands. Collectively, these and other types of wetlands distributed across the migration corridor provided a reliable network of habitat available across the Great Plains. A diversity of wetlands available during variable environmental conditions would be useful in supporting continued recovery of whooping cranes and likely have benefits for a wide array of migratory birds.

Coordinated response of endemic gastropods to Late Glacial and Holocene climate-driven paleohydrological changes in a small thermal pond of Central Europe

The thermal spring-fed Lake Pețea located in NW Romania southeast of the city of Oradea harbors a unique endemic warm water biota. It is the only location in Europe where thermal water endemic melanopsid Microcolpia parreyssii (Philippi, 1847) lived along with the highly endangered warm-water relict neritid Theodoxus prevostianus. Lake Petea’s evolution was mainly controlled by major climate-driven hydrological changes also seen in regional records. The hydrological changes were mainly controlled by varying input of thermal water due to recurring increased/decreased recharge of the underground karst water system. The driving factor was warming connected to the interstadial GI 1 increasing recharge by melting of regional ice sheets in the Late Glacial. Conversely, during the Younger Dryas (H0) and the Holocene increasing/decreasing moisture availability was in control. Low stands created multiple bottlenecks reducing genetic variability seen in the appearance of extreme morphologies during next rapid climate melioration. The studied gastropods responded mostly similarly to changes controlling the availability of elements in shell construction and habitat reduction leading to changes in shape, density, size. Periods of lower lake levels and reduced warm water input are characterized by the emergence of elongated tightly coiled shells while globular, compressed loosely coiled shells develop at times of warmer water provision and increased Mg availability. In size there is a contrasting trend. Namely globose Th. prevostianus shells are larger than the elongated ones. Conversely globose, compressed Microcolpia are generally smaller than their elongated spindle-shaped counterparts. In this sense the development of dwarf morphotypes in warmer water habitats is characteristic of Lake Pețea melanopsids. This type of dwarfism i.e. the reduction of shell size is lacking though in Lake Pețea neritids. Our findings also confirm the presence of various ecophenotypes of Microcolpia in the pond degrading our endemic species Mi. parreyssii to a variety of Mi. daudebartii.

Investigation of the Diversity of Fauna and Larval Habitat Characteristics of Culex Mosquitoes, the Potential Arboviruses Vectors in South East of Iran

Introduction: Arboviruses have been a persistent public health challenge in Iran for the past 50 years. Culex mosquitoes are the main vectors of these viruses. Different aspects of these vectors, including their phenotypic characteristics, insecticide resistance, and the potential for infection transmission, were regularly reported from different parts of the world. The present study aimed to determine the fauna and prevalence of the Culex larval stage in four sites in Kerman province, Iran from March to September 2019. Method: In total, 450 samples of Culex mosquito larvae were collected and identified using valid taxonomic keys. Physical and biological characteristics data of the larval habitats, including water situation, sunlight situation, and habitat kind, were recorded. Results: Two Culex species, Culiseta longiareolata and Culex quinquefasciatus, were detected with prevalence rates of 88.8% and 11.2%, respectively. The recorded temperatures in larval habitats ranged from 16 to 28 ◦C. Kerman City, Iran exhibited the highest prevalence of detected Culex mosquito larvae among the studied areas. Moreover, Rayen City and Sirjan City in Iran had the lowest and highest temperature rates, respectively. The temporary habitats were the most prevalent sites for larvae collection. Conclusion: This study provided a snapshot of the predominant Culex mosquito fauna in Kerman, serving as a foundation for future molecular studies, identification of insecticide-resistant fauna, and exploration of the potential for initial transmission and continuation of zoonotic infections.

Physiological adaptations to semi‐aquatic habits: the thermogenic macronutrient intake of the Eurasian otter

Abstract Maintaining thermal homeostasis in water is a major challenge for semi‐aquatic mammals, which entails morphological, behavioural and physiological adaptations. Foraging strategies and dietary‐induced thermogenesis (DIT) contribute to regulating body temperature in cold environments. As DIT differs among macronutrients, semi‐aquatic mammals may be expected to regulate their macronutrient ratios to enhance their capability of thermoregulating. We estimated the nutritional intake target of a widespread semi‐aquatic mustelid, Eurasian otter Lutra lutra by reviewing the available literature on otters' diet throughout Europe and assessing the nutritional composition of non‐commercial fish species forming the bulk of otter diet through laboratory analyses. The macronutrient intake target for the otter was assessed as 61% protein and 39% lipid energy ratios. The mean percent protein energy was higher than that reported for typical hypercarnivores and tended to increase with decreasing water temperatures. The additional source of heat provided by the thermogenic effect induced by protein digestion may contribute to balance heat loss, compensating for the costs associated with protein overconsumption. If, as suggested by fossil records, semi‐aquatic habits appeared after the development of otter's ‘fish specialist’ dentition, the thermogenic effect of its fish‐based diet may have promoted the tight relationship occurring between otters and water habitats.

Potamophylaxkosovaensis sp. nov. (Trichoptera, Limnephilidae), a new species of the Potamophylaxwinneguthi species cluster from the Ibër River Basin in Kosovo.

The Potamophylaxwinneguthi species cluster comprises species with limited distribution, currently documented from Kosovo, Serbia, Bosnia and Herzegovina and Bulgaria. In this paper, we describe a new species, Potamophylaxkosovaensis sp. nov., discovered in two tributaries of the Ibër River Basin, within the Kopaonik Mountains of the Republic of Kosovo. Morphologically, males of this species closely resemble those of P.idliri Ibrahimi, Bilalli & Kučinić, 2022 from Serbia's Jastrebac Mountain and P.humoinsapiens Ibrahimi & Bilalli, 2023 from the Sharr Mountains in the Republic of Kosovo. However, the new species can be distinguished by its smaller aedeagus, thicker and differently-shaped parameres, as well as distinctive patterns and elongated spines on the parameres. Notably, this species is restricted to spring areas, indicating sensitivity to water pollution and habitat degradation. Additionally, we provide a list of caddisfly species found in sympatry with the new species.Potamophylaxkosovaensis sp. nov. is the third known species within the Potamophylaxwinneguthi species cluster, identified in the Republic of Kosovo.

Multiple aspects of tree beta diversity in coastal ecosystems in Brazil

AbstractAimPatterns of beta diversity reflect the formation dynamics of ecological communities. Here, we integrated geographic, phylogenetic, and phenotypic information of coastal woody vegetation to investigate (1) whether the observed dissimilarity between assemblages differs from that expected by chance, examining the roles of spatial and deterministic processes; (2) the relative contribution of beta‐diversity components (turnover and nestedness) for taxonomic, phylogenetic, and functional beta diversity; and (3) what environmental factors drive the differences in composition between assemblages for all these dimensions.LocationBrazil.TaxonAngiosperm trees.MethodsWe built dissimilarity matrices and partitioned the taxonomic, phylogenetic, and functional beta diversity from an incidence matrix, a phylogeny including the region's plants, and a matrix expressing functional distances. Using linear regressions, we tested the effects of different environmental predictors representative of the effects of water availability, thermal energy, habitat heterogeneity, edaphic constraints, climatic stability, and human influence on beta‐diversity patterns.ResultsTaxonomic, phylogenetic, and functional dissimilarities exhibited a typical pattern of greater dissimilarity with distance (i.e., as expected by chance). However, these patterns showed different contributions of beta‐diversity components, predominating turnover in taxonomic and phylogenetic dissimilarity, and nestedness in functional dissimilarity. Water availability had a slight effect on patterns of taxonomic and phylogenetic dissimilarities.Main conclusionsThe Brazilian coastal woody vegetation appears to have emerged through a dynamic of colonisation of evolutionarily distinct but functionally similar lineages that originated from adjacent phytogeographic domains, proportional to their diversity. This is consistent with a combination of both neutral and non‐neutral processes. Our findings underscore the complementary roles of different dimensions of beta diversity in explaining the dynamics of these vegetation communities.

Introduction of Native Submerged Macrophytes to Restore Biodiversity in Streams.

Streams are biodiversity hotspots that provide numerous ecosystem services. Safeguarding this biodiversity is crucial to uphold sustainable ecosystem functioning and to ensure the continuation of these ecosystem services in the future. However, in recent decades, streams have witnessed a disproportionate decline in biodiversity compared to other ecosystems, and are currently considered among the most threatened ecosystems worldwide. This is the result of the combined effect of a multitude of stressors. For freshwater systems in general, these have been classified into five main pressures: water pollution, overexploitation, habitat degradation and destruction, alien invasive species, and hydromorphological pressures. On top of these direct stressors, the effects of global processes like environmental and climate change must be considered. The intricate and interconnected nature of various stressors affecting streams has made it challenging to formulate effective policies and management strategies. As a result, restoration efforts have not always been successful in creating a large-scale shift towards a better ecological status. In order to achieve an improved status in these systems, situation-specific management strategies tailored to specific stressor combinations may be needed. In this paper, we examine the potential of introducing native submerged macrophyte species to advance the restoration of stream ecosystems. Through successful introductions, we anticipate positive ecological outcomes, including enhanced water quality and increased biodiversity. This research is significant, as the potential success in restoring stream biodiversity not only represents progress in ecological understanding but also offers valuable insights for future restoration and management strategies for these vital ecosystems.

Spatial characteristics and trade-offs of ecosystem services in arid central asia

Ecosystem services (ESs) research is crucial for comprehending the intricate interplay between humans activities and the environment, particularly in ecologically sensitive regions like Central Asia, which straddles the transition from semi-arid to arid climates. Despite the ecological significance of these arid regions, research on ESs remains limited. In this study, we applied the InVEST model to analyze the spatial characteristics of multiple ESs, including water yield (WY), soil retention (SR), carbon storage (CS), and habitat quality (HQ), in Central Asia. Our findings unveil significant zonal disparities in the distribution of ESs and trade-offs across the region. WY, SR and WY-SR display distinct vertical zonation patterns, while CS and HQ exhibit both latitudinal and vertical zonation patterns. Trade-offs, with the exception of WY-SR, mostly exhibit a striped distribution pattern. Additionally, based on the GeoDetector approach, we identified key influencing factors, encompassing land use type, precipitation, evapotranspiration, temperature, vegetation coverage, soil depth, and soil organic matter. Notably, we discovered that the relationship between these factors and ESs, as well as trade-offs, is non-linear, with certain factors exhibiting optimal thresholds for maintaining either high or low levels of ESs and trade-offs.This study advances our understanding of ESs in the arid regions of Central Asia, offering valuable insights for regional ecosystem management and coordinated development. By shedding light on the non-linear dynamics of ESs and their response to influencing factors, it underscores the importance of further research to support sustainable development efforts in these regions. Future research can build upon these findings to develop policies and interventions that harness ESs for the benefit of the environment and local communities.

Establishment of Bull Trout in a previously fishless subalpine lake by translocation

AbstractObjectiveTranslocations have increased in recent years to aid in species recovery efforts. This includes translocations outside of species' historical distribution, where threats are less severe. One candidate species for translocation is the Bull Trout Salvelinus confluentus, but few examples of successful translocations (re‐establishment or range expansion) have been documented. Here, we describe an example in which 63 Bull Trout were translocated in 1987 to establish a population in fishless Marie Lake, Alberta.MethodsThe translocation was monitored through multiple sampling events over the course of 33 years. Sampling techniques included backpack electrofishing, angling, and water quality and habitat assessments.ResultA population estimate suggested that Bull Trout increased by at least fourfold over the first 12 years; fish reached large sizes (692 mm fork length) and old ages (13 years), and the population had multiple age‐ and length‐classes, including juveniles. Bull Trout also had become established within at least 13 km of river outside of Marie Lake by 2019.ConclusionAlthough a naturally reproducing population of this at‐risk species was established, numerous factors were not considered within this translocation initiative. Most importantly, nonadfluvial Bull Trout from a disparate source population located about 4000 river kilometers away were used for the translocation. Our case study represents a rare example of a successful Bull Trout translocation and highlights considerations that should occur prior to future translocations that are intended to aid in species recovery and preservation.

Ecological Insights, and Fin Fish Diversity in Carps Spawning Grounds: Case Studies from the Surma River and Tanguar Haor, Bangladesh.

This study aims to provide a thorough ecological understanding of fin fish diversity within carp spawning grounds in the Surma River and Tanguar haor. Over two spawning seasons, this research investigates ecological factors impacting fin fish diversity and abundance in carp spawning grounds of the Surma River and Tanguar haor, emphasizing water quality, habitat features, spawn availability, and environmental influences. Fish spawn samples were collected with eight "Savar nets" at chosen sites and reared in a fiberglass tank at the mini hatchery for species identification. The representative spawn samples were examined under a microscope for preliminary species identification before rearing. The study found that both the Surma River and Tanguar haor offer ideal conditions for carp spawning due to factors such as water quality, natural food availability, habitat suitability, and favorable climatic conditions. The study identified 39 fish species under the 10 fish groups from both locations, with a higher percentage of carp species (31.42%) in the Surma River in 2021 compared to 2022 (22.50%). In Tanguar haor, the percentage of carp species was 7.55% and 6.50% in 2021 and 2022, respectively. The Surma River's ecological indices (2021-2022) indicated decreased diversity, likely due to environmental degradation, while Tanguar haor showed lower diversity possibly attributable to multiple environmental stressors. The dominant carp species, Labeo calbasu, Labeo bata, and Labeo gonius, were identified in both the Surma River and Tanguar haor. The spawning distribution varied among different locations, with some sites showing a presence of carp species, such as Hajipur (T1) in the Surma River and Alam Duar (T2) in Tanguar haor. The findings highlight the importance of hydrological and environmental parameters in shaping carp spawning habitat distribution and abundance, contributing to aquatic biodiversity conservation and resource management.

Visualization of phenanthrene effect on biochar colloids transport in porous media

Biochar colloids (BCs) can be used as adsorbent materials for remediation of phenanthrene due to their high specific surface area and other characteristics. Understanding the effects of phenanthrene on the transport of BCs contributes to facilitate the removal of phenanthrene in soil and water habitats. In this work, the influence of phenanthrene on the transport of BCs under different environmental factors (pH, ionic strength (IS), media size) in a one-dimensional sand column was firstly explored together with a real-time visualization system to explore the transport mechanism of BCs in two-dimensional sand tank. The results show that phenanthrene adsorbed on the surface of BCs, shielded its surface charge and reduced the mobility of BCs in porous media. Acidic conditions promoted the agglomeration of BCs and adsorption of phenanthrene, resulting in a 51.03 % decrease in the maximum breakthrough rate of BCs compared to alkaline conditions. The same was true for the high IS condition, where the maximum breakthrough rate of BCs was only 0.95 % at IS = 50. Additionally, there was a substantial and positive correlation between media particle size and BCs mobility. As the quartz sand particle size increased, the maximum breakthrough rates of BCs were 2.67 %, 33.28 %, and 52.27 % in the 1-D experiment, and 0, 13.88 %, and 13.10 % in the 2-D experiment, respectively. The contact area of BCs with the medium expands under the fine particle size condition, leading to a significant decrease in the mobility of BCs at low potentials influenced by phenanthrene. This finding is significant for biochar application in phenanthrene contaminated soil and groundwater remediation.