Fish population dynamic in the newly impounded Nam Theun 2 Reservoir (Lao PDR)

Cottet, Maud; Descloux, Stéphane; Guédant, P.; Cerdan, Philippe; Vigouroux, Régis

doi:10.1051/hydro/2015004

Cited by 11 publications

(25 citation statements)

References 33 publications

(41 reference statements)

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“…The rapid response of these riverine fishes corresponds with previous evidence from tropical systems (Agostinho et al, 2016, ; Cottet et al, ; Henderson, Ryder, & Kudhongania, 1; Williams, Winemiller, Taphorn, & Balbas, ) and fits the general expectation of Turgeon et al () with fish populations in this tropical reservoir peaking considerably faster (0.9–1.4 years) than temperate (4.1 years) and boreal (4.5 years) systems. Although the short fill time (4 months) was clearly an important factor, the quick ecological response was primarily a consequence of the higher productivity of warm‐water ecosystems (Brown, Gillooly, Allen, Savage, & West, ; Lowe‐McConnell ).…”

Section: Discussionsupporting

confidence: 87%

“…The rapid response of these riverine fishes corresponds with previous evidence from tropical systems Cottet et al, 2015;Henderson, Ryder, & Kudhongania, 11973;Williams, Winemiller, Taphorn, & Balbas, 2011) fill time (4 months) was clearly an important factor, the quick ecological response was primarily a consequence of the higher productivity of warm-water ecosystems (Brown, Gillooly, Allen, Savage, & West, 2004;Lowe-McConnell 1987). The resultant TU parallels the response of floodplain ecosystems where seasonal inundation boosts fish populations (Agostinho, Gomes, Samuel, & Okada, 2004;Castello et al, 2015;Welcomme, 2001), inspiring the elaboration of DF as a strategy to further increase fisheries production (Sabo et al, 2017).…”

Section: Peak Timing and Durationsupporting

confidence: 85%

“…Overall, the ecological process is characterised by three trophic phases: (a) equilibrium—in accordance with the natural river before closure; (b) nonequilibrium—an upsurge, peak and decline in productivity; (c) equilibrium—in accordance with the environmental conditions of the new reservoir environment (Baranov, ). While the rise and fall of fish production following dam installation has been widely documented (Agostinho, Gomes, Santos, Ortega, & Pelicice, ; Balon & Coche, ; Benson, ; Cottet, Descloux, Guédant, Cerdant, & Vigouroux, ; Lima et al, ), its explicit time‐series character has, until recently, escaped quantitative description (Turgeon, Solomon, Nozais, & Gregory‐Eaves, ).…”

Section: Introductionmentioning

confidence: 99%

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The impact of a hydroelectric dam on Neotropical fish communities: A spatio‐temporal analysis of the Trophic Upsurge Hypothesis

Monaghan

Agostinho

Pelicice

et al. 2019

Ecology of Freshwater Fish

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We employed the trophic upsurge hypothesis as an analytical framework to describe the response of Neotropical fish communities to terrestrial inundation associated with river damming. Data were collected for the impact assessment of the Peixe Angical Dam, Tocantins River, Brazil. Monthly surveys were conducted at nine sites (seven upstream, two downstream) from 15 months before to 20 months after dam closure and a follow‐up survey 60–83 months after closure. Fish responses differed in timing and magnitude across sites. In the new reservoir, populations peaked 8–13 months after flooding, demonstrating increases in richness (84 ± 52%), biomass (329 ± 266%) and abundance (681 ± 348%) with the maxima for richness and abundance tending to precede biomass maxima. Populations of all families increased but were greatest for Engraulidae, Hemiodontidae, Serrasalmidae and Characidae, and lower for the benthic catfish: Sciaenidae, Dorididae, Pimelodidae. Downstream populations peaked 5–12 months after closure or showed consistent decline. Five years after dam‐closure richness and abundance were lower compared to predam levels, with populations at all sites demonstrating an ongoing decline. Reservoir creation triggers reproductive recruitment and otherwise pools spatially disparate populations from across the flooded valley. If the rise in richness is largely explained by the increased catchability of species otherwise present prior to flooding, it may be more appropriate to estimate species loss with reference to upsurge data. As peak biomass coincides with declining richness, modelling fisheries production from annually aggregated data may risk overestimating the potential for sustainable harvests. Upsurge–response curves can help identify the timing of critical ecological thresholds for flood‐managed fisheries.

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Section: Discussionsupporting

confidence: 87%

Section: Peak Timing and Durationsupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

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The impact of a hydroelectric dam on Neotropical fish communities: A spatio‐temporal analysis of the Trophic Upsurge Hypothesis

Monaghan

Agostinho

Pelicice

et al. 2019

Ecology of Freshwater Fish

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“…Consistent with this logic, we found that the trophic non-equilibrium phase was on average longer in boreal reservoirs compared to temperate ones. Furthermore, indirect evidence from commercial and recreational fisheries landings and knowledge of tropical reservoirs suggest that the duration of the trophic surge can be relatively short (2-10 yr; Henderson et al 1973, Balon and Coche 1974, Williams et al 1998, Agostinho et al 1999, Hallwass et al 2012, Cottet et al 2015.…”

Section: Variation In the Trophic Surgementioning

confidence: 99%

Do novel ecosystems follow predictable trajectories? Testing the trophic surge hypothesis in reservoirs using fish

et al. 2016

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Hydroelectric reservoirs are novel ecosystems that provide a variety of important services. To manage these ecosystems and their fish populations effectively, we need to develop conceptual frameworks for predicting their short‐ and long‐term responses. To advance this goal, we revisited and tested the “trophic surge hypothesis, TSH.” The TSH has been widely cited in the literature, but has not been empirically tested across numerous reservoirs. The TSH suggests that fish populations should show a hump‐shaped pattern (i.e., the non‐equilibrium phase) after river impoundment. As such, we assembled 40 recruitment and 109 adult fish abundance time series from 19 species distributed across seven reservoirs from temperate and boreal regions, and applied curve fitting analyses and model selection. We found that the hump‐shaped pattern was the predominant pattern across individual time series, providing moderate support for the TSH. Fish recruitment increased substantially during reservoir filling and was followed by an increase in adult fish lagging 3–4 years behind. The non‐equilibrium phase was transient and lasted roughly eight years for recruits, whereas it could be much longer for adults. When time series were combined across regions and sites, the support for the TSH was weaker. However, we observed significant variability in the duration, timing, and magnitude of the surge across individual time series and found that the total flooded area was the most influential predictor to explain this variability. In conclusion, the TSH and related metrics can be a useful and general predictive framework to understand how fish populations may respond to impoundment. In particular, long‐term management recommendations could be short‐sighted if formulated before convincing evidence has emerged to show that the reservoir reached its new trophic equilibrium.

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“…From April 2012 to August 2016, fish were collected from different stations of the Nam Theun 2 reservoir (17°48′N; 105°6′E) during surface gillnet surveys (gill nets: 25 × 2 m; mesh size: 10,15,20,25,30,35,40,50,60 and 70 mm between knots) conducted on a monthly basis in two reservoir stations and a quarterly basis in three additional stations (NTPC, 2014). Main features of the Nam Theun 2 area are presented in detail in Descloux, Guedant, Phommachanh, and Luthi (2016), and map and fish sampling stations in Cottet, Descloux, Guédant, Cerdan, and Vigouroux (2016). To strengthen the dataset for larger and smaller individuals, additional data were collected.…”

Section: Methodsmentioning

confidence: 99%

Length-weight relationships of eight Asian freshwater fish species in Nam Theun 2 Reservoir (Laos PDR)

et al. 2017

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Length-weight relationships (LWRs) were determined for eight Asian freshwater fish species that were not yet recorded in any peer-reviewed journal indexed in the Web of Science or the FishBase database. Fish specimens from Nam Theun 2 reservoir in Lao PDR, were collected from April 2012 to August 2016 using several methods to cover a large size-spectrum for each species. For LWRs using the general equation from Beckman (1948), the parameter b (slope value on the growth pattern) ranges from 2.908 (Puntius brevis) to 3.429 (Rasbora paviana). This study provides an update in maximum lengths for two species and first LWRs for eight common freshwater species found mainly in reservoirs, and thus represents a means for further population dynamic evolution analyses and local fisheries management

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Fish population dynamic in the newly impounded Nam Theun 2 Reservoir (Lao PDR)

Cited by 11 publications

References 33 publications

The impact of a hydroelectric dam on Neotropical fish communities: A spatio‐temporal analysis of the Trophic Upsurge Hypothesis

The impact of a hydroelectric dam on Neotropical fish communities: A spatio‐temporal analysis of the Trophic Upsurge Hypothesis

Do novel ecosystems follow predictable trajectories? Testing the trophic surge hypothesis in reservoirs using fish

Length-weight relationships of eight Asian freshwater fish species in Nam Theun 2 Reservoir (Laos PDR)

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