Effects of catchment disturbance on stream invertebrates: comparison of different habitats (vegetation, benthic and interstitial) using bio-ecological groups.

Abstract

The intensification of agriculture has drastically modified the structure of rural landscapes, changing field size, destructing hedgerow networks, and increasing nutrients and fine sediments fluxes to rivers. To evaluate the effects of these disturbances at the catchment scale, we studied the surface and interstitial water chemistry and the invertebrate assemblages in three different habitats: the vegetation, the benthic, and the interstitial. Six headwater streams ranging from undisturbed to disturbed forests (wind-fallen area) and from traditional agriculture to intensive farming areas were studied. Differences between forested and agricultural streams lie in changes in water chemistry, in habitat quality, and in the composition of the assemblages with little reduction in species richness. The forested streams were only disturbed by large-scale modifications of their catchments (i.e. wind-fallen area along the stream), which made the invertebrate assemblages similar to those of agricultural streams, even if water characteristics were not modified. In contrast, large scale modifications of landscape structure near the agricultural streams (hedgerow removal) had little effect on the fauna, but the destruction of the riparian strip (with direct access of the cattle to the river) profoundly affected the system with drastic modifications of in-stream habitat quality and invertebrate assemblage composition. The effects of these disturbances differed according to the habitat considered, with increasing differences between assemblages from the interstitial, to the benthic, and to the vegetation habitats. Finally, groups of organisms based on bioecological traits appeared as efficient tools for the evaluation of catchment disturbances, at least for the benthic and the vegetation fauna.

Leaf litter recycling in benthic and hyporheic layers in agricultural streams with different types of land use

“…This result supports our first hypothesis of a limited effect of extensive farming on invertebrates. When the riparian zone is protected and direct access of the cattle to the river is avoided, traditional agriculture has little effect on the benthic and interstitial invertebrate assemblages (Sarriquet et al 2006, Piscart et al 2009. These changes, which probably did not affect the shredder invertebrates, explain the low impact observed on the organic matter processing in coarse mesh bags.…”

Pesticide impact on aquatic invertebrates identified with Chemcatcher® passive samplers and the SPEARpesticides index

“…Freshwater ecosystems are affected by a multitude of human activities leading to catchment disturbance and water pollution, with pesticides, nutrients, polycyclic aromatic hydrocarbons (PAH), and brominated flame retardants being the most important contaminants (Malaj et al, 2014;Sarriquet et al, 2006;UNEP, 2010;Vörösmarty et al, 2010). Surface water pollution leads to adverse effects on the benthic fauna (Liess and von der Ohe, 2005;Ippolito et al, 2015) and on ecosystem functions (Bowmer, 2013;Peters et al, 2013).…”

Estimation of Sediment Hydraulic Conductivity in River Reaches and its Potential Use to Evaluate Streambed Clogging

“…The excessive inputs to, or insufficient outputs from, river reaches of fine sediments and subsequent alteration of the physical characteristics of streambed substrate are considered today as a major environmental issue (Waters, 1995;Owens et al, 2005;Sarriquet et al, 2006;Sutherland et al, 2010). Many human activities (e.g.…”