Testing predictions of changes in benthic invertebrate abundance and community structure after flow restoration in a large river (French Rhône)

2015 ◽  
Vol 60 (6) ◽  
pp. 1104-1117 ◽  
Author(s):  
Sylvie Mérigoux ◽  
Maxence Forcellini ◽  
Jeanne Dessaix ◽  
Jean-François Fruget ◽  
Nicolas Lamouroux ◽  
...  
Keyword(s):  
Community Structure ◽  
Benthic Invertebrate ◽  
Large River ◽  
Invertebrate Abundance ◽  
Flow Restoration

scholarly journals The effects of riparian forestry on invertebrate drift and brown trout in upland streams of contrasting acidity

2004 ◽  
Vol 8 (3) ◽  
pp. 578-588 ◽  
Author(s):  
S. J. Ormerod ◽  
M. E. Jones ◽  
M. C. Jones ◽  
D. R. Phillips
Keyword(s):  
Land Use ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Benthic Invertebrate ◽  
Acid Sites ◽  
Invertebrate Drift ◽  
Conifer Forest ◽  
Terrestrial Invertebrates ◽  
Invertebrate Abundance ◽  
Drift Density

Abstract. Variations in macroinvertebrate drift and benthic invertebrate abundance were assessed in 30 upland Welsh streams of varying acidity (pH < 5.7 or pH.> 6.0) and riparian land-use (conifer, moorland or native broadleaf). The consequences for the diet and condition of wild brown trout Salmo trutta were also assessed. As expected from previous studies, there were significant reductions in benthic invertebrate abundance, aquatic drift density (by >60%), aquatic drift biomass (by >35%), total drift density (by >35%) and total drift biomass (by >20%) at acid sites by comparison with circumneutral sites due largely to the scarcity of mayflies. Absolute drift from terrestrial sources was unrelated to stream pH but formed a significantly greater proportion of total drift at acid sites (30-65% of density) than at circumneutral sites (20-40%) as aquatic contributions declined. Most of this apparent land use effect reflected significantly increased terrestrial drift under broadleaves. There was no significant reduction in terrestrial or aquatic drift at conifer forest sites per se after accounting for low pH. Trout diet varied substantially between locations partly reflecting variations in drift: significantly fewer mayflies and stoneflies were eaten at acid sites, and significantly more terrestrial prey were eaten under broadleaves. However, acidity did not reduce trout condition or gut-fullness. Unexpectedly, trout condition was significantly enhanced at conifer sites, irrespective of their pH. Hence, acidity has greater effects on the benthic abundance and drift density of invertebrates in upland streams than does riparian land use. However, trout forage flexibly enough to offset any possible food deficit, for example by switching to chironomids and terrestrial invertebrates. Enhanced terrestrial contributions to invertebrate drift from riparian broadleaf trees may be important in supplementing foraging opportunities for trout where aquatic prey are scarce. These data illustrate the value of native tree species in riparian locations in upland Britain and the energy subsidy they provide might well be disproportionately important for otherwise impoverished acid streams Keywords: brown trout, land-use, acidification, drift, forestry, streams

Dispersal traits as benthic invertebrate assemblage drivers in a neotropical large river

2020 ◽  
Vol 193 (3) ◽  
pp. 275-283
Author(s):  
Miguel Saigo ◽  
Mercedes Marchese ◽  
Luciana Montalto
Keyword(s):  
Spatial Structure ◽  
Environmental Conditions ◽  
Distribution Patterns ◽  
Benthic Invertebrate ◽  
Large River ◽  
Species Dispersal ◽  
Dispersal Traits ◽  
Metacommunity Dynamics ◽  
Invertebrate Assemblage

Metacommunity theory is a mechanistic framework that explains the interdependence of local factors and regional processes as community drivers. Recent evidence suggests that dispersal mode is a key trait that potentially affects metacommunity dynamics. We analyzed the distribution patterns of benthic macroinvertebrates with different dispersal modes in the Middle Paraná, a neotropical large river. We assessed the relative importance of local environmental conditions and regional spatial structure as assemblage drivers. Aquatic and aerial dispersers presented Clementsian and Gleasonian structures, respectively. For both groups, local environmental conditions influenced community assembly, and spatial structure (overland distances) also affected the distribution of aerial dispersers. Our study highlights that the role of spatial structure as a driver of benthic metacommunities depends on species' dispersal modes. Aerial dispersers responded to regional spatial variables and it is likely that these organisms are also influenced by mass effects. Our results are consistent with current ideas of metacommunity dynamics in large rivers, where dispersal is not considered to limit the distribution of benthic organisms.

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