Cover or Velocity: What Triggers Iberian Barbel (Luciobarbus Bocagei) Refuge Selection under Experimental Hydropeaking Conditions?

Abstract

The rapid river flow variations due to hydropower production during peak demand periods, known as hydropeaking, causes several ecological impacts. In this study, we assessed the potential of an overhead cover and velocity-refuge structure in an indoor flume as an indirect hydropeaking mitigation measure for the cyprinid species Iberian barbel (Luciobarbus bocagei). We designed a lab-scale LUNKERS-type structure using two different materials which were used separately: Wood (opaque) and acrylic (transparent), tested under hydropeaking and base-flow events. Physiological (glucose and lactate) and behavioral (structure use) responses were quantified. The structure use (inside and in the vicinity) and the individual and schooling behavior was assessed. Although there was no evidence that the hydropeaking event triggered a physiological response, the wood structure use was significantly higher than the acrylic one, where the metrics of use increased in the hydropeaking event. Differences between individual and group behavior were only higher for the entrances in the wood structure. The higher frequency of wood structure use under hydropeaking conditions suggests that the visual stimulus conferred by this shaded refuge enables fish to easily find it. The results suggest that the use of overhead and velocity-refuge structures may act as an effective hydropeaking flow-refuge mitigation measure.

Experimental Investigation of Physical Leaky Barrier Design Implications on Juvenile Rainbow Trout (Oncorhynchus mykiss) Movement

“…On the other hand, the natural-colored barrier mimics more closely natural wooden formations associated with overhead cover and shelter. A study comparing a wooden against an acrylic, transparent velocity shelter (LUNKER) showed an increase in use of the wooden structure, which was assumed to be linked to visual stimuli caused by the shade (Moreira et al, 2020). Rainbow trout possess well-developed color vision (Niwa and Tamura 1969 cited by (Nakano et al, 2012)), but we know little about their attraction to color and colored objects.…”

“…The piling up of these materials also increases both barrier blockage, and longitudinal barrier length, with longer barriers providing an increase in overhead cover, an essential feature in river restoration (Heggenes & Traaen, 1988). The resulting shaded area has been found to be a visual stimulus associated with refuge and enabled fish to find the covered region (Moreira et al., 2020). A wide range of leaky barrier designs can already be found worldwide but in particular in the United Kingdom where predominantly engineered leaky barriers were installed as part of 60 Department for Environment, Food, and Rural Affairs‐funded NFM projects ([Arnott et al., 2018; Burgess‐Gamble et al., 2018], e.g., Pickering, North East England; Holnicote, South West England; Peeblesshire, South Scotland; and Shropshire, West England).…”

Evaluation of Low-Head Ramped Weirs for a Potamodromous Cyprinid: Effects of Substrate Addition and Discharge on Fish Passage Performance, Stress and Fatigue

“…At the end of each trial, to assess physiological responses to stress and fish fatigue of all tested fish, blood glucose (GLUC; mg•dL −1 ) and lactate (LACT; mmol•L −1 ) concentrations were measured using the portable meters Accucheck Aviva (Roche) and Lactate Plus (Nova Biomedical UK), respectively. The methodology applied was the same as in other studies of fish behaviour and passage performance conducted in ecohydraulic flumes [33,34,37]. The tested fish was restrained in a V-shaped padded bed, where fresh water was continuously provided, and a blood sample (0.1-0.5 mL) was collected from the caudal vasculature, using a 23 G or 25 G preheparinized needle.…”

“…In addition, along with these key physical and hydraulic parameters, physiological conditions of fish, such as stress level and fatigue, should also be considered when assessing fish passage performance [33,34]. Measurements of physiological parameters, such as glucose and lactate concentrations in blood samples, using portable point-of-care devices [35], are frequently applied to assess exercise effort and fish physiological responses to stress [33][34][35][36][37]. However, most studies are mainly focused on salmonids, as well as other game fish species such as largemouth bass or pike [35,38,39], and less is known about physiological responses for potamodromous cyprinids.…”

Impact of flow regulation for hydroelectric production in the movement patterns, growth and condition of a potamodromous fish species

“…However, there is still a lack of studies conducted with cyprinids and in an ‘in situ’ context. Most of the existent or recent studies were carried out as experiments through flumes in an ‘ex situ’ context (e.g., Costa, Boavida, Almeida, Cooke, & Pinheiro, 2018; Costa, Fuentes‐Pérez, et al, 2019; Costa, Pinheiro, et al, 2019; Moreira, Costa, Valbuena‐Castro, Pinheiro, & Boavida, 2020), which hardly represent all the habitat conditions and the complexity of factors inherent to the natural environment where fish inhabit.…”