Cyprinid swimming behaviour in response to turbulent flow

Abstract

Turbulence is a complex phenomenon which commonly occurs in river and fishway flows. It is a difficult subject to study, especially biologically, yet turbulence may affect fish movements and fish passage efficiency. Studies on quantifying fish responses to turbulence, particularly within fishways, are lacking. This study investigated the swimming behaviour of 140 adult Iberian barbel (Luciobarbus bocagei) of two size-classes (small fish: 15 ≤ TL < 25 cm, large fish: 25 < TL ≤ 35 cm) under turbulent flow conditions created by three submerged orifice arrangements in an experimental pool-type fishway: (i) offset orifices, (ii) straight orifices and (iii) straight orifices with a deflector bar of 0.5b o located at 0.2L from the inlet orifices, where b o is the width of the square orifices ranging from 0.18 to 0.23 m and L is the pool length (1.90 m). Water velocity and turbulence (turbulent kinetic energy, Reynolds shear stress, turbulence intensity and eddy size) were characterized using a 3D Acoustic Doppler Velocimeter (ADV) and were related with fish swimming behaviour. The influence of turbulent flow on the swimming behaviour of barbel was assessed through the number of successful fish passage attempts and associated passage times. The amount of time fish spent in a certain cell of the pool (transit time) was measured and related to hydraulic conditions. The highest rates of passage and the corresponding lowest times were found in experiments conducted with offset orifices. Although size-related behavioural responses to turbulence were observed, Reynolds shear stress appeared as one of the most important turbulence descriptors explaining fish transit time for both size-classes in experiments conducted with offset and straight orifices; furthermore, swimming behaviour of larger fish was found to be strongly affected by the eddies created, in particular by those of similar size to fish total length, which were mainly found in straight orifices with a deflector bar arrangement. The results provide valuable insights on barbel swimming behavioural responses to turbulence, which may help engineers and biologists to develop effective systems for the passage of this species and others with similar biomechanical capacities.

Assessing hydrodynamic space use of brown trout, Salmo trutta, in a complex flow environment: a return to first principles.

“…Further, the importance of turbulence is well recognised, and a variety of different metrics (e.g. TI: Smith et al, 2005;RTI: Cotel et al, 2006;TKE: Smith et al, 2006;and τ: Hayes and Jowett, 1994;Silva et al, 2011Silva et al, , 2012aDuarte et al, 2012) have been used to define suitable habitat or migratory routes, although such statistical links remain difficult to interpret from an ecological perspective. However, attempts to quantify hydrodynamic space use by fish living in lotic environments frequently fail to consider both drag and turbulence together.…”

“…Third, laboratory studies continue to attempt to find statistical links between patterns of fish distribution/ movement and one or more of any number of turbulent flow characteristics, such as turbulence intensity (TI), relative turbulence intensity (RTI), turbulent kinetic energy (TKE), turbulent length scale (TLS) or Reynolds shear stresses (τ) (e.g. Smith et al, 2005Smith et al, , 2006Silva et al, 2011Silva et al, , 2012aDuarte et al, 2012). However, the biophysical interpretation of these statistical links remains obscure.…”

Análise do comportamento hidráulico de um mecanismo de transposição de peixes do tipo escada com ranhura vertical em duas declividades

“…Para que isso ocorra um MTP deve ser eficiente na atração de peixes, permitindo sua passagem de modo seguro, sem danos e com um custo mínimo de energia e de tempo. Portanto, o sucesso de um projeto de MTP depende tanto do estudo da capacidade natatória de peixes quanto da análise dos parâmetros hidráulicos e estruturais mais adequados do mecanismo para a passagem aos peixes migrantes durante a piracema (SILVA et al, 2012).…”

“…Vários autores apresentam valores máximos de dissipação de energia dentro do sistema. Bell (1973) (SILVA et al, 2012). A tensão de cisalhamento de Reynolds está relacionada à transferência contínua de quantidades de movimento entre massas de água adjacentes com diferentes velocidades.…”

Ascent ability of brown trout,Salmo trutta, and two Iberian cyprinids − Iberian barbel,Luciobarbus bocagei, and northern straight-mouth nase,Pseudochondrostoma duriense− in a vertical slot fishway

“…Most of the existing work was performed in laboratory settings and focused on the hydraulic preferences of fish within pool-type fish ladders (Silva et al, 2009;Silva et al, 2012;Branco et al, 2013). The relevance of these data to field conditions is not well-established, however, and more work is needed to verify the principles learned in the laboratory (Thiem et al, 2013).…”