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Wetlands are considered as the heart of natural feeding and breeding grounds of many indigenous fishes of Bangladesh. These are also the most diversified habitat in the world. However, the wetlands of Bangladesh are in danger of extinction due to various manmade and natural causes. Therefore, wetlands need special attention to conserve this unique ecosystem of Bangladesh. As a part of the conservation measures needed for wetland ecosystem, the present study was undertaken to describe the abundance and diversity status of fish in Dingapota wetland of Bangladesh and to identify the key environmental factors influencing the fish community assemblage. A total of 52 fish species were recorded from 7 orders during the study period. Cypriniformes comprises the most abundant order (47.91%) followed by Perciformes (20.71%) and Clupeformes (20.22%). Higher number of species was recorded in post-monsoon season. Fish community assemblage was significantly differentiated among the three seasons (ANOSIM, Global R = 0.803, P < 0.05), while the overall average differences in the period of three seasons was estimated as 39.92% and similarity percentage analysis (SIMPER) revealed the greater contribution of Osteobrama cotio, Esomus danricus, Nandus nandus, Gudusia chapra and Chanda nama to ascertain this dissimilarity. Multivariate analysis based on non-metric multidimensional scaling (nMDS) generated three separate groups of each seasonal samplings and cluster analysis to find out natural grouping of samples according to their abundance. Diversity indices (Shannon-Weiner diversity (H), Margalef’s richness (D) and Pielou’s evenness (e)) were found to vary significantly among the seasons. Canonical correspondence analysis (CCA) revealed the significant roles of temperature, depth, transparency, pH, dissolved oxygen and alkalinity for structuring the community assemblage of fish in Dingapota wetland. Essential baseline information generated by this study will help the respective authority to formulate sustainable conservation measures for Dingapota wetland. [ABSTRACT FROM AUTHOR]

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Indigenous Knowledge can be defined as expertise, skills, practices, ideas, experiences and information gained over a long period, sustained and passed on from generation to generation orally within a community in a particular geographic area, often forming part of its culture. The Sundarbans, the largest remaining tract of coastal mangrove wetlands in the world are surrounded by rivers, rivulets, and creeks pushing the islanders to pursue fishing as a source of subsistence. The present paper has sought to understand how the fishing community of the Sundarbans draws upon his repertoire of knowledge and beliefs to cope with the world in which it finds itself. This has required an understanding of not only the Sundarban's natural world, but its geomorphology, hydrology and also the social world--the people, economy, administration, and governance. Using the ethnographic method, this empirical study deals with the fishers' means and measures i.e. beliefs, cognitive elements, and techniques--while often preserving the traditional fabric, have evolved with time. This unique and effective indigenous knowledge needs to be conserved. Documentation of the existing valid indigenous knowledge with fishers' perception as well as scientific rationale will help in adoption and further improvement to fulfil the present need of the people. [ABSTRACT FROM AUTHOR]

Human alterations, such as hydropower development, are intensive and have negative impacts on fish and ecological environment. However, fish habitat restoration projects based on geographical morphology have not yet been reported in the Yangtze River. To explore engineering measures used to restore fish habitat structure and function, a mesoscale fish habitat restoration project was designed and constructed, which included restructuring of habitat topography in the fluctuating area. Three-dimensional computational fluid dynamics (CFD) models were used to simulate and predict the project's effect on the hydromorphology prior to construction, and an Acoustic Doppler current profiler (ADCP) was deployed to test and verify actual flow field improvement. Short-term effects on fish species sorting and their main ecological traits were examined. The results showed that vorticity and flow heterogeneity in the river reach increased, suggesting that the restoration projects created flow conditions favourable to indigenous fishes. Thus, pre-optimization using computer simulation is an essential and scientific procedure that could be used to increase the probability of river restoration success. The promotion of habitat diversity had strong effects on fish aggregation, especially for the rare and endemic fish species targeted. Fish abundance, catch biomass and species richness increased by 98.1%, 62.7% and 22.5%, respectively. There were significant differences (p < 0.05) in species number and catch abundance before and after the project. The number of rare and endemic fish species increased from four to nine species. Overall, this research provides evidence that the promotion of habitat hydraulic morphology heterogeneity accelerates the recovery of fish diversity and biomass. [ABSTRACT FROM AUTHOR]

The conservation and management of inland fish and freshwater ecosystems immensely contribute to global sustainable development. The existing 'Protected Area' (PA) network does not represent freshwater resources well and seldom considers its fish communities, while designating PAs. A study was undertaken to quantitatively assess the role played by the three terrestrial PAs (IUCN category IV) in conserving fish diversity and preserving habitat quality in the river reaches bordering the three PAs of the river Pranhita. It is a unique river system in the Indian Deccan Plateau in terms of fish diversity and community structure. Field surveys were conducted during the non-monsoon and monsoon seasons in 2020–21, that recorded 53 species including endemic and threatened fishes from river Pranhita, which represent more than one-third the number of fish species of Telangana state. The higher diversity and lower dominance index value (p < 0.01) reported in PAs compared to Eco Sensitive Zones and unprotected areas during the non-monsoon season indicate the role of intact physical habitat in providing refuges to the fish species in monsoon dependent tropical rivers. The optimal water quality revealed no significant difference (p > 0.0001) between protected and unprotected river reaches, and healthy biotic integrity assessed on the basis of fish community structure was attributed to the contiguous flow and less anthropogenic disturbance. This study supports that it can be considered as a representative zone for the conservation and protection of indigenous and endemic fish species of the Godavari Basin. The results concluded that the scope of the terrestrial PA network in India could be potentially extended to their bordering aquatic ecosystems, especially rivers to maintain pristine habitat conditions and conserve the fish genetic resources to ensure the flow of ecosystem services. [ABSTRACT FROM AUTHOR]

The design and implementation of appropriate management actions to tackle the spread and negative impacts of non-indigenous fish species (NIFS) in freshwater ecosystems still remains a complex task. In an effort to address the limitations of current managerial approaches, our study develops and applies a classification framework to define non-indigenous fish assemblage types (FATs) in Mediterranean riverine ecosystems and identifies the linkage with various regional, local, biotic and abiotic environmental factors. This framework contributes to a pre-invasion stage screening and to the design of effective type-specific post-invasion management actions dealing with specific NIFS assemblages. A network analysis was applied in order to extract NIFS community level information from 393 samples obtained from 51 river basins of Greece, while a multivariate ordination analysis was conducted to detect the factors best explaining the structure and distribution of FATs. The association patterns of the study's inputs and outcomes are illustrated through an alluvial diagram, providing insights across different spatial scales. In total, five FATs were generated where the major NIFS contributors of average similarity within each modularity class revealed the key indicator species (Gambusia-FAT; Carassius/Lepomis-FAT; Pseudorasbora-FAT; Salmonids-FAT and Carp-FAT). Overall, the identified FATs varied spatially, indicating different community structure, mainly based on the diverse habitat preferences and life-history traits of indicator species. Alien FATs were mainly distributed within large and transboundary rivers, while Translocated and Salmonids FATs mostly occupied ecoregions with relatively depauperate faunas and often in biodiversity hotspots. The results of this study can identify conservation priorities within FATs, inform specific-type post-invasion management actions tackling NIFS, while in addition may provide valuable information for protecting high-priority water bodies before invasion. • A network analysis approach classified non-indigenous riverine fish assemblages. • Five non-indigenous fish assemblage types and six indicator species were generated. • Fish community-level information and distributional patterns were extracted. • Assemblages were shaped by diverse habitat preferences and indicator species' traits. • Post-invasion management insights across different spatial scales are provided. [ABSTRACT FROM AUTHOR]