scholarly journals Drought Facilitates Species Invasions in an Urban Stream: Results From a Long-Term Study of Tropical Island Fish Assemblage Structure

2018 ◽  
Vol 6 ◽  
Author(s):  
Alonso Ramírez ◽  
Pablo E. Gutiérrez-Fonseca ◽  
Sean P. Kelly ◽  
Augustin C. Engman ◽  
Karleen Wagner ◽  
...  
Keyword(s):  
Fish Assemblage ◽  
Assemblage Structure ◽  
Urban Stream ◽  
Fish Assemblage Structure ◽  
Term Study ◽  
Tropical Island ◽  
Species Invasions ◽  
Long Term Study

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 Long-term effects of a rural landscape on the structure and trophic organization of a fish assemblage

2019 ◽  
Vol 31 ◽  
Author(s):  
Pedro Sartori Manoel ◽  
Virginia Sanches Uieda
Keyword(s):  
Fish Assemblage ◽  
Assemblage Structure ◽  
Rural Landscape ◽  
Environmental Data ◽  
Diet Analysis ◽  
Fish Diet ◽  
Fish Assemblage Structure ◽  
Long Term Effects ◽  
Over Time

Abstract Aim We investigated the long-term effects of a rural landscape on the structure and trophic organization of a fish assemblage. Methods We compared environmental data and data from fish assemblage structure and trophic organization sampled in a stream located in a rural area, within a time gap of 20 years. Results We observed only punctual changes in the environmental variables and fish structure, which may not be related to the rural landscape. In fish diet, insectivory remained predominant in all sample periods. However, when we analyzed the groups of hexapods consumed by the fish species, we found a substitution of Ephemeroptera and Trichoptera by Diptera over time. Conclusions Although the fish assemblage structure was not affected, the insectivore diet analysis showed that the stream stretch could be in an ongoing process of environmental quality loss, once the simplification in the macroinvertebrates assemblage structure over time is indicative of environmental degradation.

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