Determination of the Effect of Water Depth and Flow Velocity on the Quality of an In-Stream Habitat in Terms of Climate Change

Abstract

The study is focused on the objectification of an assessment of the quality of an in-stream habitat in mountain and piedmont streams by the decision-making Instream Flow Incremental Methodology (IFIM) due to climate change. The quality of the habitat was assessed on the basis of a bioindication, represented by ichthyofauna. Sixty-four reaches of 47 watercourses in five river basins in Slovakia, in which ichthyologic, topographic, and hydraulic measurements were performed, were evaluated. The effect of the physical characteristics of the stream channel on the quality of the in-stream habitat has been verified on a number of reference reaches in which the measurements were performed at different water levels. From the set of the data measured, an analysis aimed at determining the impact of individual characteristics on the quality of an in-stream habitat has been carried out. The results show the optimum ratio of the weights of the flow velocity and water depth for an assessment of the quality of an in-stream habitat due to climate change.

Influence of discharge on fish habitat suitability curves in mountain watercourses in IFIM methodology

“…• The correlation between the suitability curve parameters for the depths and the hydraulic characteristics of a river has been confirmed in our previous studies (Macura et al, 2016). Therefore, we assume that the HSCs can be generalized for certain areas with different flow depths.…”

“…This type of activity has a negative impact on the biota of rivers, and typically results in decreased biodiversity (Cianfrani et al, 2009;Palmer et al, 2010). The negative impacts are further exacerbated by intense climate change (Van Loon et al, 2015), mainly by intense droughts during the summer seasons (Macura et al, 2016).…”

Evaluation of the Methodology to Assess the Influence of Hydraulic Characteristics on Habitat Quality

“…Despite the strong evolutionary adaptations of individual species, the decreasing rate is higher in the scenario of the combination of warming and the flow reduction, which inevitably leads to a high probability of population extinction [12]. The evaluation of the impact of climate change on the quality of the aquatic habitat on the Drietomica stream (piedmont) shows that, during the 2071-2100 horizon, the minimum flow rates will fall by 50% in the summer [13]. Such changes can also be expected in other mountain and piedmont streams of the Carpathian system.…”

The Effect of Gabions on the Quality of a Stream Habitat

“…Most fish species prefer certain combinations of water depths, velocity rates, bedding material and hiding possibilities. Information about the influence of velocity rate and depth of the water on habitat preferences is also sufficient, for example in Macura et al (2016). However, there is a lack of information on the impact of the environment material, especially on the impact of the stabilisation material.…”

“…Several authors report that a suitable bioindicator of the environment is brown trout, because it responds sensitively to the changes in flow velocity and depths of the stream (Hooper, 1973;Shirvell and Dungey, 1983;Reiser and Wechse, 1976;Macura, 2016). Alpine bullhead and the stone loach are less sensitive to morphological changes.…”