scholarly journals Conservation biogeography of lotic fishes in the Missouri and Colorado River basins

2019 ◽  
Author(s):  
◽  
Landon Lee Pierce
Keyword(s):  
Species Distribution ◽  
Fish Assemblage ◽  
Native Species ◽  
Species Distribution Models ◽  
Colorado River ◽  
River Basins ◽  
Assemblage Structure ◽  
Native Fish ◽  
Fish Assemblage Structure ◽  
Distribution Models

To improve our understanding of lotic fish ecology and improve conservation efforts, I 1) identified potentially ecologically important tributaries (PEITs) and evaluated their effects on fish assemble structure, 2) evaluated factors affecting spatial transferability of species distribution models (SDMs), and 3) evaluated the drivers of non-native fish establishment in the Missouri and Colorado River basins (MRB and CRB). The effects of PEIT likely vary among rivers as all Missouri River PEITs affected fish assemblage structure, but only half of upper Colorado River basin PEITs affected fish assemblage structure. Species distribution models transferred from the MRB to the CRB for 15 of 25 species, but transferability was not predictable based on species characteristics, re-enforcing the hypothesis that transferability is species-and contextspecific. Support for Human Activity, Biotic Resistance and Biotic Acceptance hypotheses as the drivers of non-native fish establishment varied by family, but these hypotheses rarely explained significant variability in the probability of non-native Salmonidae, Catostomidae, and Cyprinidae occurrence. These results may suggest that other factors (e.g., natural factors) drive non-native species distributions at the spatial (i.e., grain-stream segment; extents-physiographic divisions, and MRB and CRB combined) and taxonomic (i.e., family) scales considered in this study. This study aids conservations efforts by providing an efficient approach for identifying ecologically important tributaries and improving predictions of non-native species establishment.

scholarly journals Longitudinal patterns in distribution of native and non-native fish species in a regulated temperate Neotropical river

2021 ◽  
Vol 33 ◽  
Author(s):  
Andrea Bertora ◽  
Fabián Grosman ◽  
Pablo Sanzano ◽  
Juan José Rosso
Keyword(s):  
Dissolved Oxygen ◽  
Fish Species ◽  
Environmental Conditions ◽  
Fish Assemblage ◽  
Native Species ◽  
Assemblage Structure ◽  
Native Fish ◽  
Fish Assemblage Structure ◽  
Longitudinal Patterns ◽  
Tolerant Species

Abstract: Aim We evaluated the longitudinal patterns in distribution of native and non-native fish species in a hydrologically fragmented and environmentally variable lowland temperate river. Methods Four sites representing contrasting habitat and environmental conditions were sampled: a clear water reservoir, a turbid water lagoon and two river reaches with clear and turbid waters each. Environmental variables were measured in situ and in the laboratory. Fishes were sampled using trammel and beach seine nets. Results Two main environmental scenarios were identified: the upstream reaches, with colder, clearer and nutrient-oxygen poor waters (reservoir and its downstream river) and the downstream reaches, where turbidity, dissolved oxygen, water temperature, conductivity and nutrients largely increased (lagoon and its downstream river). Fourteen species with a high non-native/native (4:10) ratio were collected. Non-native species (NNS) were confined to lentic conditions, where the silverside Odontesthes bonariensis dominated. Native species (NS) better thrive in lotic conditions where the turbid scenario further favored tolerant species. Environmental conditions also seemed to influence the distribution of NNS. Fish assemblage structure considering either, all species, NNS or NS significantly differed among sampled reaches and habitat (lentic-lotic) conditions. Total fish abundance was higher in lentic reaches. Species richness and diversity were favored by the turbid scenario. Beta diversity was mostly explained by the replacement component revealing the substitution of species as the main pattern of variation. Water conductivity, nitrates and dissolved oxygen were the most important predictor variables in the best and most frequent explanatory models of fish assemblage structures. Conclusions Our results revealed that a low diversified Neotropical fish fauna is disrupted by habitat fragmentation due to the creation of artificial impoundments and the introduction of NNS. Environmental conditions further modulate the fish assemblage structure by affecting the distribution of species where tolerant species were favored by turbid, nutrient-rich waters with higher conductivity and pH.

scholarly journals Fish Assemblage Structure in Al-Huwaizah marsh southern of Iraq after inscribed on the World Heritage List

2019 ◽  
pp. 1430-1441
Author(s):  
Basim M. Hubain Al-Thahaibawi ◽  
Kadhim H. Younis ◽  
Ithar K.A. Al-Mayaly
Keyword(s):  
Fish Assemblage ◽  
Native Species ◽  
Similarity Index ◽  
Chemical Properties ◽  
Assemblage Structure ◽  
Total Weight ◽  
Fish Assemblage Structure ◽  
Dominance Index ◽  
Fish Samples ◽  
Index Value

The fish assemblage structure in Al-Huwaizah marsh, southern of Iraq was assessed. Fish samples collected monthly by different fishing means from period December 2017 to November 2018. A total of 28959 individual of fish belonging to 9 families and 19 species were collected, 11 of them of native species and 8 of alienspecies. The numerical dominance index value (D3) of the highest three abundant species comprised 74.26% of the total fish caught, included Planiliza abu (Al-Keshny) 38.2% ; Coptodon zilli (Tilapia red abdomen) 29.41% and Carassius auratus (Prussian carp) 6.65%. The total weight of fish caught 2,190,680 tan, highest weight 312,242kg achieved in July, while lowest weight 41,590 kg found in September. The weight dominance index value (D3) of the highest three species in weight recorded 1,409,973 tan of the total weight of fish caught included C. zilli(Tilapia red abdomen) 659,994 kg , S. triostegus (Jerry fresh water) 495,784 kg and O. aureus (Blue tilapia) 245,195kg.The annual rate value for diversity, richness and evenness indices amounted 1.88, 1.75 and 0.64, respectively. Some of physical and chemical properties were studied such as water temperature which ranged from 11.5°C in January to 31.02°C in August month, dissolved oxygen ranged from 2.24 mg/l in September to 9.9mg/l in February, salinity varied from 1.37‰ in November to 3.76‰ in September and pH which ranged from 7.4 in June to 8.15 in December.Jaccard Similarity Index (Ss%) was used to know the similarity degree between the monthly catch samples. Also associations between distribution of fish species and the environmental variables were quantified by using canonical correspondence analysis (CCA). 

scholarly journals Constructing ecological indices for urban environments using species distribution models

2021 ◽  
Author(s):  
Ariel Levi Simons ◽  
Stevie Caldwell ◽  
Michelle Fu ◽  
Jose Gallegos ◽  
Michael Gatheru ◽  
...  
Keyword(s):  
Los Angeles ◽  
Species Distribution ◽  
Indicator Species ◽  
Environmental Conditions ◽  
Native Species ◽  
Species Distribution Models ◽  
Urban Environments ◽  
Ecological Indices ◽  
Distribution Models ◽  
The Mean

Abstract In an increasingly urbanized world, there is the need for a framework to assess ecological conditions in these anthropogenically dominated environments. Using species observations from the Global Biodiversity Information Facility (GBIF), along with remotely sensed environmental layers, we used MaxEnt to construct species distribution models (SDMs) of native and non-native species in Los Angeles. 25 native and non-native Indicator species were selected based on the sensitivities of their SDM, as measured by the Symmetric Extremal Dependence Index (SEDI), to environmental gradients. These SDMs were summarized to produce ecological indices of native and non-native biodiversity in Los Angeles. We found native indicator species to have a greater sensitivity to environmental conditions than their non-native counterparts, with the mean SEDI score of native and non-native species MaxEnt models being 0.72 and 0.71 respectively. While both sets of species were sensitive to land use categories and housing density, native species were more sensitive to natural landscape variables while non-native ones were more sensitive to measures of water and soil contamination. Using random forest modeling we also found our native index could be more reliably predicted, given environmental conditions, than its non-native counterpart. The mean Pearson correlation between actual and predicted index values were 0.86 and 0.84 for native and non-native species. From these results we conclude that using SDMs to predict the biodiversity of environmental species is a suitable approach towards evaluating ecological conditions in urban environments, with the environmental sensitivity of native SDMs outperforming non-native ones.

scholarly journals Long-term study of reservoir cascade in south-eastern Brazil reveals spatio-temporal gradient in fish assemblages

2018 ◽  
Vol 69 (12) ◽  
pp. 1983 ◽  
Author(s):  
Raquel Coelho Loures ◽  
Paulo Santos Pompeu
Keyword(s):  
River Basin ◽  
Fish Species ◽  
Fish Assemblage ◽  
Native Species ◽  
Fish Assemblages ◽  
Native Fish ◽  
Fish Diversity ◽  
Fish Assemblage Structure ◽  
Long Term Study

In reservoir cascades, effects on fish assemblages are expected to strengthen over time and transfer from one reservoir to an adjacent one. To test this, fish-assemblage data from 23 years of monitoring in the Araguari reservoir cascade system, upper Paraná River basin, were analysed. The results showed a clear reduction in richness of native and migratory fish species and an increase of non-native species, following reservoir formation. Migratory species richness was higher in reservoirs that presented habitats similar to lotic stretches or tributaries upstream of the impounded area. There was a clear tendency for native species to decline and non-native fish species to increase, in a downstream direction. Fish assemblages became increasingly dissimilar as reservoirs became more distant from each other (longitudinal gradient) and were dominated by small and medium-sized species. Alongside longitudinal position, reservoir area, age and the presence of herbivorous non-native fish were found to be important predictors of variation in fish-assemblage structure. Results from the present study help clarify the potential accumulated impacts of reservoir cascades on fish diversity, which must be carefully considered in river-basin inventories for hydropower plants, and reinforce the importance of long-term monitoring, considering longitudinal and lateral dimensions of the basin.

scholarly journals An invasion risk map for non-native aquatic macrophytes of the Iberian Peninsula

2017 ◽  
Vol 74 (1) ◽  
pp. 055 ◽  
Author(s):  
Argantonio Rodríguez-Merino ◽  
Rocío Fernández-Zamudio ◽  
Pablo García-Murillo
Keyword(s):  
Iberian Peninsula ◽  
Species Distribution ◽  
Native Species ◽  
Aquatic Macrophytes ◽  
Species Distribution Models ◽  
Green Revolution ◽  
High Sensitivity ◽  
Risk Map ◽  
Invasion Risk ◽  
Distribution Models

Freshwater systems are particularly susceptible to non-native organisms, owing to their high sensitivity to the impacts that are caused by these organisms. Species distribution models, which are based on both environmental and socio-economic variables, facilitate the identification of the most vulnerable areas for the spread of non-native species. We used MaxEnt to predict the potential distribution of 20 non-native aquatic macrophytes in the Iberian Peninsula. Some selected variables, such as the temperature seasonality and the precipitation in the driest quarter, highlight the importance of the climate on their distribution. Notably, the human influence in the territory appears as a key variable in the distribution of studied species. The model discriminated between favorable and unfavorable areas with high accuracy. We used the model to build an invasion risk map of aquatic macrophytes for the Iberian Peninsula that included results from 20 individual models. It showed that the most vulnerable areas are located near to the sea, the major rivers basins, and the high population density areas. These facts suggest the importance of the human impact on the colonization and distribution of non-native aquatic macrophytes in the Iberian Peninsula, and more precisely agricultural development during the Green Revolution at the end of the 70’s. Our work also emphasizes the utility of species distribution models for the prevention and management of biological invasions.

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