Ecological impacts of excessive water level fluctuations in stratified freshwater lakes

Zohary, Tamar; Ostrovsky, Ilia

doi:10.5268/iw-1.1.406

Cited by 345 publications

(294 citation statements)

References 66 publications

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“…Many studies have been conducted to assess the influence of WL variations on the community of fish or other aquatic organisms (Pompeu, Godinho, 2006;Paulovits et al, 2007;Baumgärtner et al, 2008;Zohary, Ostrovsky, 2011;Dutterer et al, 2013). These studies demonstrated that both the fluctuations of water levels in natural environments (caused by annual cycle and climate change), as well as in reservoirs and other artificial water bodies, promoted impacts on the fish communities and other components of the aquatic biota, as well as in water quality parameters.…”

Section: E160084[2]mentioning

confidence: 99%

Effects of reservoirs water level variations on fish recruitment

2017

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The construction of hydroelectric power plants has many social and environmental impacts. Among them, the impacts on fish communities, which habitats are drastically modified by dams, with consequences across the ecosystem. This study aimed to assess the influence of water level (WL) variations in the reservoirs of the Itá and Machadinho hydroelectric plants on the recruitment of fish species from the upper Uruguay River in southern Brazil. The data analyzed resulted from the WL variation produced exclusively by the hydroelectric plants generation and were collected between the years 2001 and 2012. The results showed significant correlations between the abundance of juvenile fish and the hydrological parameters only for some reproductive guilds. The species that spawn in nests showed, in general, a clear preference for the stability in the WL of the reservoirs, while the species that spawn in macrophytes or that release demersal eggs showed no significant correlation between the abundance of juvenile fish and hydrological parameters. A divergence of results between the two reservoirs was observed between the species that release semi-dense eggs; a positive correlation with a more stable WL was only observed in the Machadinho reservoir. This result can be driven by a wider range of WL variation in Machadinho reservoir.Keywords: Hydrological Parameters, Itá, Juveniles, Machadinho, Reproduction, Uruguay River.A construção de usinas hidrelétricas implica em diversos impactos sociais e ambientais. Dentre esses, o impacto causado sobre a comunidade de peixes, cujos habitats são drasticamente modificados pelas barragens, causam consequências em todo o ecossistema. Este trabalho teve como objetivo avaliar a influência da variação dos níveis de água dos reservatórios das usinas hidrelétricas de Itá e Machadinho sobre o recrutamento das espécies de peixes do alto rio Uruguai, sul do Brasil. Os dados analisados resultaram da variação de nível de água decorrente exclusivamente da operação da usina e foram coletados entre os anos de 2001 e 2012. Os resultados mostraram correlações significativas entre a abundância dos juvenis de peixes e os parâmetros hidrológicos apenas para determinadas guildas reprodutivas. As espécies que desovam em ninhos mostraram, em geral, uma clara preferência pela estabilidade do nível de água dos reservatórios, enquanto que as espécies que desovam em macrófitas ou que liberam ovos demersais não mostraram correlação significativa entre a abundância de juvenis com os parâmetros hidrológicos. Uma divergência de resultados entre os dois reservatórios foi observada entre as espécies que liberam ovos semi-densos, onde apenas no reservatório de Machadinho houve correlação positiva com a maior estabilidade do nível de água. Esse resultado pode ser motivado pela maior amplitude de variação do nível de água no reservatório de Machadinho quando comparado com o de Itá.

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Section: E160084[2]mentioning

confidence: 99%

Effects of reservoirs water level variations on fish recruitment

2017

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“…<4.5 m, compared to Valdovinos et al, 2007;Zohary and Ostrovsky, 2011;Eloranta et al, 2016), is expected to reduce occupation of the littoral zone by native species in the presence of the introduced rainbow trout (Hanisch et al, 2012;Otturi et al, 2016). However, the abundant large rocks and semisubmerged coastal trees present in the Alicurá reservoir seem to provide the necessary structure and refugia for native species, as revealed by the observation of P. trucha less than 10 cm in length using the shallow littoral in protected bays, along with G. maculatus and juvenile ERT (D. Nabaes Jodar, unpublished data).…”

Section: Discussionmentioning

confidence: 92%

Native and exotic fishes in a Patagonian reservoir with rainbow trout cage culture: spatial and trophic resource use

Jodar

Becker

Blasetti³

et al. 2017

Knowl. Manag. Aquat. Ecosyst.

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-Although the interactions of exotic salmonids with native Patagonian fishes are well known, little is known about the ecology and impact of farmed fish escapees. Salmonid production in Argentina is largely concentrated in the Alicurá reservoir in north Patagonia, where fish community studies have been scarce. Here, we assess and compare the spatial distribution, body size-condition and diet of the different fish species in this reservoir. Strong vertical segregation was observed between exotic rainbow trout Oncorhynchus mykiss (both escapees and wild), dominating the littoral zone, and native Percichthys trucha which dominate the medium and deep strata. Low piscivory-benthivory and high zooplanktivory were observed for rainbow trout, both traits being uncommon at a regional scale. Escaped farmed rainbow trout (ERT) diet included abundant indigestible items along with wild prey. Higher body condition of P. trucha close to farms, as well as the regionally unprecedented high incidence of Daphnia sp. in the guts of all the species suggest that farm nutrient discharges have had significant impacts. Finally, the high body condition of ERT, together with their wild food diet and the long dispersal distance observed, demonstrate post-escape success, drawing our attention to potential upstream dispersion affecting the biodiversity and fisheries of Patagonian rivers and lakes.Keywords: aquaculture impact / freshwater salmonid / niche segregation / diet / Patagonia Résumé -Poissons indigènes et exotiques dans un réservoir de Patagonie avec aquaculture en cage de truites arc-en-ciel : utilisation des ressources spatiales et trophiques. Bien que les interactions des salmonidés exotiques avec les poissons patagoniens indigènes soient bien connues, on connaît peu l'écologie et l'impact des poissons échappés d'élevage. La production de salmonidés en Argentine est largement concentrée dans le réservoir d'Alicurá dans le nord de la Patagonie, où les études sur les communautés de poissons ont été rares. Ici, nous évaluons et comparons la répartition spatiale, la taille du corps et l'alimentation des différentes espèces de poissons dans ce réservoir. Une ségrégation verticale forte a été observée entre la truite arc-en-ciel exotique Oncorhynchus mykiss (à la fois évadée et sauvage), dominant la zone littorale et Percichthys trucha natif qui domine les couches moyennes et profondes. Un faible comportement piscivore-benthivore et un régime zooplanctivore important ont été observés pour la truite arc-en-ciel, les deux traits étant peu fréquents à l'échelle régionale. Le régime de la truite arc-en-ciel échappée des cages (ERT) comprenait des composés indigestes abondants et des proies sauvages. Un coefficient de condition élevé de P. trucha près des fermes, ainsi que l'incidence locale sans précédent de Daphnia sp. dans les estomacs de toutes les espèces suggère que les rejets de nutriments aquacoles ont eu des impacts importants. Enfin, le bon état corporel des ERT, ainsi que leur régime alimentaire et la longue distance de ...

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“…We did not consider the "water level stability" as single factor, but we considered it between the threats, according to Keto et al (2006) and Zohary and Ostrovsky (2011) indicating that drastic water level fluctuations (fluctuations out from the normal cyclical ranges) are disadvantageous for aquatic species. Also, waters coming not from the natural water cycle ("alien waters inputs") was considered as threat for similar reasons and for their relative pollution risks.…”

Section: Ecological Assessment Proceduresmentioning

confidence: 99%

A new multi-criteria method for the ecological assessment of lakes: A case study from the Transboundary Biosphere Reserve ‘West Polesie’ (Poland)

et al. 2017

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A new multi-criteria method of evaluation and assessment of the ecological status of lakes is proposed. It is based on macrophytes analysis integrated with geomorphological, landscape and catchment sources of threats. A total of 22 lakes in the Transboundary Biosphere Reserve 'West Polesie' (Poland) were investigated along trophic (available nutrients) and human pressure gradients, testing the proposed method with ESMI and TRS indices. Therefore, the present indexation included 22 criteria (i.e., catchment land use, phytolittoral area, number of plant species) concerning three different assessing zones (lakeshore, littoral and surrounding area), and provided a five-class ecological classification. The proposed index, in addition to the general ecological conditions assessment of lakes, allows to point out a zonal evaluation, identifying the most critic zones in terms of ecological status. The proposed method can be universally adapted for any type of lakes, regardless of their geographical characteristics. It can be applied to system monitoring, and to support lakes biodiversity, functionality, conservation, restoration, water protection and uses, as well as water, territory and landscape management actions.

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Ecological impacts of excessive water level fluctuations in stratified freshwater lakes

Cited by 345 publications

References 66 publications

Effects of reservoirs water level variations on fish recruitment

Effects of reservoirs water level variations on fish recruitment

Native and exotic fishes in a Patagonian reservoir with rainbow trout cage culture: spatial and trophic resource use

A new multi-criteria method for the ecological assessment of lakes: A case study from the Transboundary Biosphere Reserve ‘West Polesie’ (Poland)

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