Spatial distribution patterns of benthic macroinvertebrate functional feeding groups by stream size and gradient in Republic of Korea

Abstract

Benthic macroinvertebrate functional feeding groups (FFGs) are influenced by the availability of food sources, which can be affected by stream size and gradient. We investigated the spatial distribution patterns of FFGs by stream size (stream order, catchment area and stream width) and gradient (altitude and slope). In addition, we attempted stream classification based on the distribution patterns of FFGs. To achieve these goals, a total of 996 sampling sites of national scale located in the Republic of Korea were investigated from 2008 to 2016. Among the five physical variables, stream width and slope showed linear relationships with the indicator values of FFGs. These two physical variables had larger influences on the distribution of FFGs compared to other variables. Geology (the type of rocks) showed little influences on the distribution of benthic macroinvertebrate communities. We classified streams focusing on catchment (stream size) area and altitude (stream gradient) because they are constants that do not change with disturbances. The FFGs and benthic macroinvertebrate assemblages were distinctly changed by stream types, indicating that the stream classification criterion adequately represented changes in physical variables in biotic terms. In addition, the distribution of FFGs and biotic assemblages showed that benthic macroinvertebrates in the Republic of Korea were more influenced by the altitude (stream gradient) than the catchment area (stream size). In overall, this study found that the stream size and gradient markedly influence the distribution of FFGs in national regions of the Republic of Korea. Further research is needed focusing on the level of microhabitats and other parameters to identify the promising variables that influence biotic distribution.

Distribution patterns of benthic macroinvertebrate communities based on multispatial-scale environmental variables in the river systems of Republic of Korea

“…In this study, similar to the previous two studies, stream size increased, overall shredders decreased and collectors increased (Figure 4). In addition, in Min et al (2019), when the stream size became very large, collectors decreased, and in this study, the results were the same in groups 5 and 6, which included many larger sites compared to other groups. In this study, variables corresponding to the stream size, such as stream order and stream width, affected biological distribution, although their influence was low as indicated by high correlation with canonical discriminant function 2 in the discriminant analysis and axis 2 in the CCA.…”

“…In light of these results, altitude, along with latitude, is likely to be used as an indicator environment for cold-water organisms instead of water temperature. Min et al (2019) and Vannote et al (1980) roughly classified stream types according to the stream size, and then confirmed the distribution of FFGs. Based on the individual abundance, shredders decreased and collectors increased from the upstream to the downstream, showing opposite results.…”

“…Stream width was measured as the distance from bank to bank by a laser range finder (Bushnell Inc., Overland Park, KS, USA) at three sampling points per sampling site, and then averaged. Altitude was measured for each stream gradient using a GPS unit (Triton 500; Magellen Inc., San Dimas, CA, USA) at representative sampling point per sampling site, and gradient was obtained by applying the method described by Min et al (2019) using ArcGIS (version 10.2; ESRI, Redlands, CA, USA). All microhabitat variables were measured at three sampling points per sampling site, and then averaged.…”

“…Therefore, in order to accurately identify the distribution of biotic communities according to water temperature, sampling should be conducted on the same day, at the same time, but this is practically impossible. On the other hand, since the altitude is a variable with little change in the short and long term (Min et al 2019), it is believed that is had a greater influence on the distribution of biotic communities than water temperature. In light of these results, altitude, along with latitude, is likely to be used as an indicator environment for cold-water organisms instead of water temperature.…”

“…Limestone zones were known to be more suitable for mollusks because they have higher concentrations of magnesium and calcium ions than granite zones, besides they have buffer action (Carrie et al 2015). But in the Republic of Korea, geology has little influence on benthic macroinvertebrate communities (Min et al 2019), so it was not considered in this study.…”