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The lack of knowledge about freshwater biodiversity in remote areas like montane Andean rivers is noticeable and hinder the development of efficient conservation plans for aquatic ecosystems. Habitat requirements of tropical Andean fishes have been poorly analysed, despite the relevance of these ecological features on the fish conservation strategi...
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... present study includes 101 sampling points in six basins located in Colombia, Ecuador and Peru into the Andean mountain range ([ 500 m above sea level, Table 1). From North to South, the first basin is the Suaza River, belonging to the Magdalena Basin, which drains most Colombian Andes to the Caribbean Sea. ...Citations
... In other words, specific taxa disappeared from monocultures, but these changes were not reflected in the alpha diversity metric applied [i.e., Shannon diversity index; expressed as the number of equally abundant species but see Martínez et al. (2009)]. Further, fish abundance and community composition showed little relation with anthropogenic disturbance, including pastures and croplands encroachment (Miranda et al., 2022). A meta-analysis aimed at assessing dung beetles' responses to land-use changes (Nichols et al., 2007), using richness, abundance, and community similarity, found that secondary forest and agroforestry could harbour sensitive species that are lost in agriculture and cattle grazing lands (Nichols et al., 2007). ...
... The monoculture sites include mainly palmetto and non-shaded cacao plantations. The five taxonomic groups were chosen due to their widespread use as bioindicators in the Neotropics and given their sensitivity to land use change (i.e.: Chao et al., 2014;Chapman et al., 2018;European Comission, 2000;Fulgence et al., 2022;Larsen & Forsyth, 2005;Miranda et al., 2022). Additionally, the availability of comprehensive data for all these groups within the same geographical area and across the existing major land-use typologies enhances ecological understanding. ...
... The sites on forest tributaries are the ones that overlap with monoculture sites, more influenced by low habitat diversity than by land use. Hydro-morphological features highly influence fish communities in the tropical Andes more than agricultural uses (Miranda et al., 2022), which can explain the overlap between forest-monoculture fish communities. Macroinvertebrates, unlike our expectations, showed weak differences across land use typologies. ...
Land-use change is a primary driver of biodiversity loss. Tropical ecosystems face rapid conversion rates due to the encroachment of agricultural lands and supply needs for goods and services from an increasing population and changing market demands. Measuring the effect of land conversion on species diversity is challenging due to incomplete and uneven knowledge of different taxonomical groups. Here, we contrast different metrics for measuring biodiversity loss across three land-use typologies: secondary forest, agroforestry, and monoculture for five taxonomic groups: birds, frogs, fish, dung beetles, and macroinvertebrates in the Andean piedmont forests of the western equatorial Andes. Albeit our limited and uneven sample in space and time, we found that rarity, Non-Metric Multidimensional Scaling, and Multinomial Classification Model (i.e., classifications of habitat specialists and generalists) constitute a more sensitive set of indicators to assess land-use change impacts on tropical mountain biodiversity compared to classical metrics. Likewise, our results showed that land-use intensification influenced community assemblages in the five taxonomic groups. These non-classical biodiversity metrics can provide better insight into the effect of land conversion on these highly biodiverse ecosystems composed of many rare species.
... While in other parts of the reservoir, fishing pressure is quite strong, in these areas, there is theoretically little or no fishing. However, the two areas of LAI are not closed off from the lake so that fish can migrate, but they are large enough (several tens to hundreds of hectares) to develop stronger subpopulations of some species [49][50][51]. The differences between the LAI and HAI areas' fish communities may also be caused by some inherent differences between the west and east side of the lake, which are not related to anthropogenic pressure. ...
Freshwater protected areas are designated parts of the inland waters that restrict human activities. They were created as a mechanism to combat the decline of fauna and flora of the world. Some authors have questioned their actual effectiveness in terms of the purpose of protecting endangered fauna and flora. We conducted an experiment in Lipno reservoir in the Czech Republic to evaluate the impact of protection against angling pressure on the fish community. We selected data from two years of gill netting and analyzed the difference between areas of low anthropogenic impact (LAI) and those of high anthropogenic impact (HAI) in terms of abundance, biomass, standard length, and diversity indices. Three groups of fish were found to prefer protected areas with low anthropogenic pressure: 1. YOY (Young-of-the-year) perch (Perca fluviatilis), the dominant of the young-of-the-year fish community. 2. Pike (Esox lucius), wels catfish (Silurus glanis) and rudd (Scardinius erythrophthalmus), which were not found in HAI areas at all. 3. Larger individuals of pikeperch (Stizostedion lucioperca), which survived better in LAI areas. Some factors may affect LAI, such as illegal poaching or setting out food bait to attract the fish outside. Another factor that can be considered is the migration of fish, either to forage or to reproduce, since the LAI areas are open to the reservoir. The areas of LAI act as protective habitats for heavily exploited predatory fish species and increase fish diversity indexes. The example of the protected and low-impact areas of Lipno should be followed in other water bodies with high fishing pressure and anthropogenic impact.
The problem of salt water intrusion into the Mekong Delta is a research topic involving various branches of science. Among the causes of this phenomenon are global sea level rise and regulation of the natural river discharge due to hydropower dam construction. The scale of the delta and its water dynamics complicate instrument-based observations. Meanwhile, communities of living organisms can serve as indicators of environmental heterogeneity. This study aimed to analyze the spatial variability of fish assemblage organisation in the Mekong Delta for use as an indicator of salt water intrusion. The composition of fish assemblages in different parts of the delta were determined by midwater trawl catches during January and April 2021. A total of ~15 thousand individual fish from 74 trawl hauls were captured and analyzed. The null hypothesis was that the fish assemblages in the Mekong Delta are represented by three taxonomic complexes that are localized in the upper course (freshwater), the lower course (brackish) and the middle course (zone of the contact of the fresh and brackish waters) of the delta. The taxonomic composition of the freshwater complex is the most poor and is represented by 9 families. Meanwhile, marginal (the contact zone) and brackish complexes include 26 and 23 families, respectively. Specimens of families Cobitidae, Eleotridae, Plotosidae and Siluridae that are only found in the zone of contact of fresh and brackish waters could be considered as indicator species of its position. The actual boundaries of the brackish and freshwater complexes were determined and the distance from them to the marine delta edge equals 34 and 78 km, respectively. Assessment of the salinity values that correspond to the complex boundaries is a task for future investigation. The position of the boundaries of freshwater and brackish fish taxonomic complexes has a biological basis and could be used as an indicator of salt water intrusion into the Mekong Delta.
Malaysia’s rapid economic and demographic development have placed negative pressure on its water supplies and the quality of the Juru River, which is close to the nation's capital and its major source of water. Healthy aquatic ecosystems are supported by physicochemical properties and biological diversity. This study evaluated the anthropogenic impacts on aquatic biodiversity, especially plankton, fish, and macrobenthos, as well as the water quality of the Juru River in the Penang area. Aquatic biodiversity and river water parameters were collected from ten sampling stations along the Juru River. Seven variables were used to assess the physicochemical environment: pH, temperature, total suspended solids (TSS), salinity, dissolved oxygen (DO), biochemical oxygen demand (BOD), and chemical oxygen demand (COD). At each sampling station, the total number of plankton, fish, and macrobenthic taxa were counted and analyzed. The relationships between the physicochemical parameters and aquatic biodiversity were investigated with biotypological analysis, principal component analysis, hierarchical cluster analysis, and linear regression analysis. These analyses showed that the richness and diversity indices were generally influenced by salinity, temperature, TSS, BOD, and pH. The data obtained in this study supported the bioindicator concept. The findings, as they related to scientifically informed conservation, could serve as a model for Juru River management, as well as for river management throughout Malaysia and other tropical Asian countries.
