Current and substrate preferences of benthic invertebrates in the rivers of the Hindu Kush-Himalayan region as indicators of hydromorphological degradation

Abstract

The study introduces an approach to obtaining information about the preferences of benthic invertebrates for substrate and current velocity in a region with little prior knowledge of benthic invertebrates. These preferences are then used for river assessment. Substrate-specific sampling of 271 reference sites was conducted in lower mountainous and lowland areas of the Hindu Kush-Himalaya region. Statistical analysis revealed significant preferences for substrate type and current velocity for 50 taxa of Ephemeroptera, Plecoptera, Trichoptera, Coleoptera, Diptera, Odonata, Mollusca, and Oligochaeta. A 20-point system was developed to assign scores for substrate and current preferences. Scores from seven taxa of Ephemeroptera and Trichoptera revealed low ecological potential in response to habitat alteration. These data were used to develop four preference metrics. The Lithal metric is composed of 34 taxa with significant preferences for stony substrates (fine gravel to bedrock size). The Lithophile metric contains 21 taxa with strong statistical links to stony substrates, which were also found on other substrates. The Lithobiont metric consists of 13 taxa exclusively found on stones. The Lotic metric consists of 11 taxa with significant preferences for moderate-to-fast current velocities. Multi-habitat sampling was conducted at 181 sites reflecting a hydromorphological gradient. The Mann-Whitney U test and box-and-whisker plots were applied to test the relationship of the new metrics to hydromorphological stress. Of the four new metrics, the Lithal, Lithophile, and Lotic were able to detect impacts of hydromorphological degradation.

www.freshwaterecology.info – An online tool that unifies, standardises and codifies more than 20,000 European freshwater organisms and their ecological preferences

“…Armanini et al (2010) developed a flow sensitivity index for Canada and used freshwaterecology.info content for validation purposes. Korte (2010) compared the current and substrate preference of indicators developed for the Hindu Kush-Himalayan region with preferences of European species. Von Bertrab et al (2013) used functional traits to assess species' responses to fine sediment input.…”

Analysis of benthic macroinvertebrate communities from the Lower sections of Large river in relation to different environmental factors

“…The main factor affecting the composition of riverine macroinvertebrates is water current; i.e., determining the presence or absence of limnetic or lotic taxa [4][5][6][7]. The velocity of the current indirectly affects water retention time, which is one of the most important factors shaping the physicochemical conditions and qualitative and quantitative structure of all aquatic organisms [1].…”

Hydroclimatic and hydrochemical controls on Plecoptera diversity and distribution in northern freshwater ecosystems

“…Early work showed that Plecoptera have a clear preference for colder streams and lakes; their distribution in warmer streams is much more restricted (Baumann, 1979). Similarly, Plecoptera have often been identified as having specific hydraulic flow preferences, with a general preference for higher flows (rheobiont), but ability to tolerate standing waters (limnobiont) in some groups so long as temperatures are low (Mérigoux et al, 2009;Korte, 2010;Tierno de Figueroa et al, 2010).…”