Factors affecting fish assemblage structure during seasonal stream drying

Dekar, Matthew P.; Magoulick, Daniel D.

doi:10.1111/j.1600-0633.2006.00226.x

Cited by 44 publications

(40 citation statements)

References 19 publications

(30 reference statements)

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“…According to day vertical beaming data, downstream fish density in Siliana Reservoir was lower than the middle and upstream strata, while biomass was higher, consistent with big fish occupying deep water and small fish occupying shallower upstream areas. These results are in accordance with the study of Dekar and Magoulick (2007), where fish density was negatively related to maximum depth, and with the study of Power (1987), who asserts that increasing maximum depth can result in greater predation risk from larger aquatic predators. In Masri, Joumine and Sidi-el-Barak reservoirs, statistical analyses indicated no biomass gradient existed across strata; nevertheless, assessment could be improved with specific species size-weight relationships of fish from Tunisian reservoirs.…”

Section: Discussionsupporting

confidence: 94%

Hydroacoustic fish biomass assessment in man-made lakes in Tunisia: horizontal beaming importance and diel effect

Djemali

Toujani

Guillard³

2008

Aquat Ecol

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We used a Simrad EK60 echosounder equipped with two split-beam transducers to develop a sampling strategy for assessing fish resources in Tunisian man-made lakes. Day and night surveys, using vertical and horizontal beaming, were carried out between December 2006 and February 2007, a period when fish catchability is high. Four reservoirs with differing surface areas and bathymetries were selected. Echogram analysis revealed that fish communities were mainly composed of individual targets. A few schools were detected near the surface during daylight, but these schools dispersed slightly at night. In these multispecies reservoirs, considerable day and night differences in density existed, but with no clear trend. Target strength (TS) distribution mode values detected at night were always lower or equal to daytime values. Biomass estimates were significantly higher during daytime in three reservoirs, corresponding with higher TS modal values. In the other reservoir, the biomass estimate was significantly higher during nighttime corresponding with higher mean density during this period. Using only a vertically aimed transducer in our study reservoirs would have led to an underestimate of density and biomass by 5-100% and 20-100%, respectively, depending on the man-made lake. We conclude that acoustic sampling in our reservoirs must be done during day and night and that both vertical and horizontal beaming must be used to obtain the best possible picture of the fish stocks.

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Section: Discussionsupporting

confidence: 94%

Hydroacoustic fish biomass assessment in man-made lakes in Tunisia: horizontal beaming importance and diel effect

Djemali

Toujani

Guillard³

2008

Aquat Ecol

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“…The important role played by periodically inundated or temporary habitats as fish nursery and feeding areas has been demonstrated (Cucherousset et al 2007), as has the role of isolated waterbodies as refugia from disturbance associated with drying (Magoulick & Kobza 2003;Dekar & Magoulick 2007). However, despite the recognized ecological value of temporary habitats, prior studies have not considered entirely ephemeral catchments, nor the behaviour of their resident biota through time.…”

Section: Discussionmentioning

confidence: 97%

Fish movement strategies in an ephemeral river in the Simpson Desert, Australia

Kerezsy¹,

Balcombe²,

Tischler

et al. 2013

Austral Ecology

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Arid zone catchments experience extreme hydrological variability and some rivers are entirely ephemeral, replenished only by intermittent flooding. The ecological roles of ephemeral systems are rarely studied. This paper describes movement patterns of fish in the Mulligan River, an ephemeral system in the Lake Eyre Basin, central Australia. Several sites were sampled along a temporal gradient encompassing floods and dry periods. After a single major flood in 2007 up to seven fish species were found at sites up to 300 km from the closest permanent waterhole. Following a series of floods (when waterholes were replenished and remained wet between 2009 and 2011) a further five species were recorded including the first records for the Lake Eyre hardyhead, Craterocephalus eyresii, from the rivers of far western Queensland.The presence of all species known from the parent catchment (the Georgina, where permanent waterholes occur) in the ephemeral catchment (the Mulligan) suggests that many fish species present in the river systems of central Australia are capable of dispersing long distances following the opening of movement pathways during flooding. However, two distinct groups of species were identified: extreme dispersing species, that move as far as possible into intermittently wetted habitats, and conservative dispersing species, that do not move as far, tending to inhabit deeper waterholes within mid-reaches of the river that are more likely to hold water for longer. Preservation of the natural flow regime of Australia's arid-zone rivers is important for maintaining these fish communities and facilitating study of their adaptations to ephemerality.

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“…Small streams in Gr2 are under threat of drying out. Fish can survive in such streams providing there exist some refugia with sufficiently deep water (Dekar and Magoulick 2007). Dams tightened by beavers lead to water retention during a drought.…”

Section: Discussionmentioning

confidence: 99%

Beaver impact on stream fish life histories: the role of landscape and local attributes

Bylak

Kukuła

MitkaJózef

2014

Can. J. Fish. Aquat. Sci.

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The Eurasian beaver (Castor fiber) has been reintroduced into the Carpathian Mountains and has once again become an important factor for modifying streams. Forty-three sampling sites were compared with 10 reference sites in streams not settled by beavers. Models related to the impacts of beavers on various fish life history stages and a model presenting attributes influencing the ichthyofauna structure in streams with and without beavers were generated. Significant differences in the fish species composition were found between beaver ponds versus the running sections of streams. The changes associated with pond aging caused decrease of Siberian bullhead (Cottus poecilopus) density. For brown trout (Salmo trutta), beaver ponds were the only location where large individuals were found, while the upstream parts of the beaver complexes provided spawning habitat and an area for fry growth. Common minnow (Phoxinus phoxinus) and stone loach (Barbatula barbatula) had higher density in ponds than in streams. The decisive factors for the ichthyofauna in the mountain streams settled by beavers were local attributes related to beaver activity. Our results illustrate interactions among beaver, landscape context, and fish life history in influencing the response of the stream fish assemblages to beaver recolonization. It also helps answer the question of how Eurasian beaver influence stream fish assemblages, at a much larger scale than previous studies. Résumé :Le castor d'Eurasie (Castor fiber) a été réintroduit dans les Carpates, où il est redevenu un important facteur de modification des cours d'eau. Quarante-trois sites d'échantillonnage ont été comparés à 10 sites de référence de cours d'eau non fréquentés par des castors. Des modèles associés aux impacts des castors sur différentes étapes du cycle biologique des poissons et un modèle qui présente les attributs qui ont une incidence sur la structure de l'ichtyofaune dans les cours d'eau avec et sans castors ont été produits. Des différences significatives sur le plan de la composition des espèces de poissons ont été décelées entre les étangs à castors et les tronçons à écoulement rapide de cours d'eau. Les changements associés au vieillissement de l'étang entraînaient une diminution de la densité de poissons-chats (Cottus poecilopus). En ce qui concerne la truite brune (Salmo trutta), les étangs à castors étaient les seuls endroits où de grands individus étaient observés, alors que les parties amont des complexes à castors leur fournissaient un habitat de frai et une aire de croissance des alevins. Les densités des cyprinidés (Phoxinus phoxinus) et des loches (Barbatula barbatula) étaient plus grandes dans les étangs que dans les cours d'eau. Les facteurs déterminants pour l'ichtyofaune dans les cours d'eau de montagne colonisés par les castors étaient des attributs locaux associés à l'activité des castors. Nos résultats illustrent le fait que les interactions entre les castors, le paysage et le cycle biologique des poissons ont une incidence sur la réaction des assemblag...

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Factors affecting fish assemblage structure during seasonal stream drying

Cited by 44 publications

References 19 publications

Hydroacoustic fish biomass assessment in man-made lakes in Tunisia: horizontal beaming importance and diel effect

Hydroacoustic fish biomass assessment in man-made lakes in Tunisia: horizontal beaming importance and diel effect

Fish movement strategies in an ephemeral river in the Simpson Desert, Australia

Beaver impact on stream fish life histories: the role of landscape and local attributes

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