Effects of weir construction on fish population structure in the River Erro (North of Spain)

Abstract

In 1996, a compound gauging weir was built in Villaveta Township (Navarra, North of Spain) in the river Erro (Ebro River Basin). Before and after its construction, fish and physical and chemical variables were examined to determine weir's impact on the reach. Fish captured by electrofishing were measured (total length), and population density and length distribution of the species were estimated. Species diversity (Shannon's diversity index), dominance (Simpson's dominance index) and evenness were also calculated. The results revealed an increase in fish population density, especially in smaller specimens, but a decrease in the larger fishes. Substrate and shelter alterations could explain the observed variations in the fish community. In order to improve the consolidation of well-developed fish populations, the placement of great boulders and the restoration of the riparian vegetation are suggested.

Microgeographic genetic isolation in chub (Cyprinidae: Squalius cephalus) population of the Durance River: estimating fragmentation by dams

“…The consequences of this loss of connectivity in river systems is comparable to the losses observed in terrestrial systems: species find it difficult to migrate (seasonal movements for reproduction) and disperse (exchange between populations) (Lucas & Frear 1997), habitat complementation (accessibility of the different necessary habitats) is lost (Madéore-Le Pichon 2006), and population sizes are reduced, potentially leading to population extinctions (Fagan 2002). Indeed, it has been shown that entire fish communities can be affected by weirs (Miranda et al 2005;Poulet 2007), and cyprinid species often make up the major part of fish communities of the middle and lower reaches of temperate rivers (Winfield & Townsend 1991). Fish are potentially highly impacted by fragmentation.…”

“…However, fragmentation may also be important for non migratory species with low clearing capacities such as cyprinids. Indeed, it has been shown that entire fish communities can be affected by weirs (Miranda et al 2005;Poulet 2007), and cyprinid species often make up the major part of fish communities of the middle and lower reaches of temperate rivers (Winfield & Townsend 1991). Moreover, many cyprinids may have to cover considerable distances for reproduction and feeding (McKeown 1984;Northcote 1984), and one can hypothesise that such species would be sensitive to smaller obstacles than salmonids, since they are generally smaller themselves and less able to clear obstacles (Bainbridge 1958;Ovidio & Philippart 2002).…”

Komposisi jenis dan struktur komunitas ikan yang bermigrasi melewati tangga ikan pada Bendung Perjaya, Sungai Komering, Sumatera Selatan

“…dan beberapa jenis ikan asli dan ekonomis di Sungai Kampar Riau akibat pembangunan Waduk Kutopanjang dan hilangnya spesies ikan asli Sungai Cincingguling akibat dibangunnya waduk Sempor Jawa Tengah (Putri et al, 2013). Hasil penelitian Miranda et al (2005) mengungkapkan adanya perubahan struktur komunitas ikan di Sungai Erro Spanyol, yaitu adanya peningkatan dalam kepadatan populasi ikan, terutama pada spesies yang lebih kecil namun terjadi penurunan pada ikan-ikan yang berukuran lebih besar. Agostinho et al (2008) melaporkan bendungan sangat mempengaruhi komposisi dan struktur komunitas ikan di Brazil.…”

Spatial and Temporal Dynamics of Potentially Toxic Cyanobacteria in the Riverine Region of a Temperate Estuarine System Altered by Weirs

“…These structures can change riverine systems to lacustrine conditions [10,14]. When riverine waters become impounded, changes in water quality and biota are detected [15,16]. For example, the Murray River in Australia has been observed to be more favourable to cyanobacterial growth in areas where weirs were installed, as opposed to free-flowing areas [17].…”