Effects of Riparian Vegetation Integrity on Fish and Heteroptera Communities

Abstract

Abstract. Freshwater ecosystems are essential to human societies. However, many anthropogenic activities have been constantly modifying these ecosystems. Such modifications can be detected and measured with the use of environmental bioindicators. This work aims to identify the effect of physical integrity of streams, riparian vegetation coverage and physical and physicochemical variables on fish and Heteroptera faunas of streams, identifying which group is a better indicator of environmental disturbance. Predictor variables were sorted into three matrices: (1) physical and physicochemical parameters of the streams, (2) environmental variables and (3) structural variables of riparian vegetation. We tested the effects of physical and physicochemical descriptors on species richness and abundance through multiple linear regressions. The effects of environmental and structural variables of the riparian vegetation were tested using ridge regressions. Physical and physicochemical variables had no effect on Heteroptera and fish communities. Environmental variables showed effect only on the community of Heteroptera. Ichthyic assemblages were not influenced by any environmental variables. Selected structural variables had no relation with the Heteroptera assemblages, neither with fish community. Therefore, we conclude that, in small Amazonian streams, Heteroptera is more sensitive to human impacts than fish. This sensibility is demonstrated by the negative relation between Heteroptera fauna and the canopy opening over the river and positively related to environment integrity. These associations were not found for icthyofauna.

Testing a Generalizable Machine Learning Workflow for Aquatic Invasive Species on Rainbow Trout (Oncorhynchus mykiss) in Northwest Montana

“…There were a few such products whose lack of explanatory power can be attributed to temporal lag effects, scale mismatch, or model uncertainty. For example, EVI has been used as a proxy for submerged aquatic vegetation in open water systems ( Massicotte et al, 2015 ), although the connection to species richness in streams is less clear ( Vieira et al, 2015 ). Thus, EVI may not translate to ecologically relevant conditions for RBT within the spatial and temporal scale of our study.…”

Effects of Environmental Changes on Gerromorpha (Heteroptera: Hemiptera) Communities from Amazonian Streams

“…It also decreases possible seasonality effects [35][36][37]. Therefore, the collection of field data in studies of Heteroptera ecology in Brazil are mostly carried out during the dry season [15,16,21].…”

“…Changes in the aquatic community structure, such as changes in richness and species composition patterns may be a consequence of changes in the environmental conditions (e.g., air and water temperature, flow speed, depth, channel width, and type of substrate on the channel and the stream banks) and resource availability (e.g., leaves and wood packs that are used for shelter and food, nesting sites, and foraging substrates) [14]. The structure of aquatic communities in Amazonian streams is affected both by environmental variables related to land-use change (resources and environmental conditions) at the landscape scale, and variables at the local scale, such as changes in habitat integrity, in the structure of the channel edges, the type of substrate on the streambed, the presence of leaf and wood packs, and water quality [15,16].…”

“…The Heteroptera (Hemiptera) have been frequently used in studies that evaluate anthropized aquatic environments in the Amazon region [15,16,[21][22][23]. The Gerromorpha, an infraorder within the Heteroptera order, is comprised of semiaquatic individuals that move on the water surface preying upon other aquatic insects that emerge from the aquatic environment, and those that fall from the marginal vegetation.…”

“…Previous studies claimed that the Heteroptera were resistant to environmental change [27]. However, more recent studies have shown negative effects of environmental change on Heteroptera communities [15,16,21,[24][25][26]28]. Ephemeroptera, Plecoptera, Trichoptera, and Odonata were considered to be more sensitive to losses of habitat integrity in tropical streams than Heteroptera [18].…”