Agricultural intensity and landscape structure: Influences on the macroinvertebrate assemblages of small streams in northern Germany

Abstract

The present study aimed to relate aquatic macroinvertebrate community composition to agricultural intensity and landscape structure. A total of 360 streams were investigated within the Aller river basin in northern Germany. The study area is typical of central German arable agricultural regions, but the small streams were of low dilution potential. These streams were characterized for abiotic parameters (including modeled potential for diffuse inputs from agricultural sources) and macroinvertebrate communities, with data collected over a 17-year period. Spray drift potential did not correlate with community composition. In contrast, the relative index of runoff potential (RP) was negatively correlated with various measures of taxonomic richness and abundance. Community composition also was correlated with environmental parameters, including stream width, clay content of sediment, and presence of dead wood in sediment. The abundance of sensitive species decreased significantly during the main period of agrochemical use at sites of high RP but completely recovered by the following spring. Long-term decreased taxonomic richness and a shift to ecologically robust species also were observed at sites of high RP. The results suggest that long-term alterations in community measures probably were associated with factors related to runoff input. Nevertheless, the community composition remained reasonably rich and even. Landscape structure also appeared to influence community structure. Abundance of sensitive species remained significantly enhanced, even at sites of high RP, when forested reaches were present in upstream reaches. These probably provided a source of organisms for downstream recolonization and amelioration of effects at high RP.

Buffer strip width and agricultural pesticide contamination in Danish lowland streams: Implications for stream and riparian management

“…anthropogenic stressors (Schäfer et al, 2007(Schäfer et al, , 2011a. Furthermore, Schriever et al (2007b) found 60 that SPEAR pesticides was the biological parameter best describing stream macroinvertebrate 61 community responses to a modelled indicator of pesticide surface runoff (RP). In contrast, 62 Rasmussen et al (2011) were unable to link RP with SPEAR pesticides using a large dataset of small 63 Danish streams, which could be due to the presence of wider buffer strips along Danish streams 64 compared to German streams.…”

Macroinvertebrate responses to insecticide application between sprayed and adjacent nonsprayed ditch sections of different sizes

“…The current experimental ditch study (see also López-Mancisidor et al [23] and Brock et al [26]), a few field observations in streams (e.g., [15,[44][45][46]) and a simulation study using a metapopulation model [18] suggest that the ecological impact on insects and crustaceans may be smaller in exposed sections of water courses if only part of the system suffers insecticide stress. However, an important question at stake is: ''At the landscape level, how large should be the surface area of, and distance to, uncontaminated refuges to allow an overall acceptable impact (including recovery and effects at a distance) of pesticide-stress on populations and communities?'…”

A similarity‐index–based method to estimate chemical concentration limits protective for ecological communities

“…The RP of a site was based on the log 10 -transformed load (g) of a generic compound that could enter the water body along a 1,500-m stretch upstream. Runoff potential was correlated with other indicators of agriculture intensity, but the major effect of RP on macroinvertebrates in the Aller Catchment is from pesticide runoff and not from other causes [17]. We split the data set into five RP categories: very low, defined as RP > À10 but 4 (n ¼ 40 samples); low, > À4 but 3 (60); moderate, > À3 but 2 (100); high, > À2 but 1 (120); and very high, > À1 but 0 (40).…”

“…We used a macroinvertebrate data set [17] We related change in species occurrence to an index of runoff potential (RP) [17]. The RP of a site was based on the log 10 -transformed load (g) of a generic compound that could enter the water body along a 1,500-m stretch upstream.…”