Habitat loss due to dam development may affect the distribution of marine‐associated fishes in Gabon, Africa

Cutler, Joseph S.; Olivos, J. Andres; Sidlauskas, Brian L.; Arisméndi, Iván

doi:10.1002/ecs2.3024

Cited by 8 publications

(5 citation statements)

References 29 publications

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“…Although dam removal (reviewed in e.g. Bednarek, 2001;Tonitto and Riha, 2016;Ding et al, 2019) is optimal solution of strong interaction between generalist fishes and rheophilic fishes, the global trend is to increase proportions of rivers that will be affected by damming (Grill et al, 2015;Zarfl et al, 2015;Winemiller et al, 2016;Cutler et al, 2020). In cases where restoration of degraded environments are not possible, there is a possibility to disrupt the connection between the remaining unoccupied tributary to isolate the habitats that are already occupied by generalist species (Rahel, 2013).…”

Section: Temporal Habitat Displacement Of Rheophilic Species By Gener...mentioning

confidence: 99%

Living on the edge: Reservoirs facilitate enhanced interactions among generalist and rheophilic fish species in tributaries

Šmejkal

Bartoň

Duras

et al. 2023

Front. Environ. Sci.

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Most lotic ecosystems have been heavily modified in recent centuries to serve human needs, for example, by building dams to form reservoirs. However, reservoirs have major impacts on freshwater ecosystem functions and severely affect rheophilic fishes. The aim of this review is to gather evidence that aside from direct habitat size reductions due to reservoir construction, competition for food and space and predation from generalist fishes affect rheophilic community compositions in tributaries (river/stream not directly affected by water retention). River fragmentation by reservoirs enables the establishment of generalist species in altered river sections. The settlement of generalist species, which proliferate in reservoirs and replace most of the native fish species formerly present in pristine river, may cause further diversity loss in tributaries. Generalist migrations in tributaries, spanning from tens of metres to kilometres, affect fish communities that have not been directly impacted by reservoir construction. This causes “edge effects” where two distinct fish communities meet. Such interactions temporarily or permanently reduce the effective sizes of available habitats for many native specialized rheophilic fish species. We identified gaps that need to be considered to understand the mechanistic functioning of distinct fauna at habitat edges. We call for detailed temporal telemetry and trophic interaction studies to clarify the mechanisms that drive community changes upstream of reservoirs. Finally, we demonstrate how such knowledge may be used in conservation to protect the remnants of rheophilic fish populations.

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Section: Temporal Habitat Displacement Of Rheophilic Species By Gener...mentioning

confidence: 99%

Living on the edge: Reservoirs facilitate enhanced interactions among generalist and rheophilic fish species in tributaries

Šmejkal

Bartoň

Duras

et al. 2023

Front. Environ. Sci.

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“…Humans have altered natural river connectivity in multiple ways by placing structures in the longitudinal or lateral flow paths, such as dams and levees [85]. Dams and reservoirs, along with their upstream and downstream propagation of fragmentation and flow regula-tion, are the leading contributors to the loss of river connectivity [85,86]. The construction of new hydroelectric power plants, such as the Baixo Iguaçu HPP hydroelectric power plant that is in operation, will result in the loss of habitats and restrict the area of occurrence of the S. melanodermatum, which may cause a decrease in genetic diversity via fragmentation.…”

Section: Discussionmentioning

confidence: 99%

Deep Pools: Ecological Sanctuaries for Steindachneridion melanodermatum, a Large Endemic and Endangered Pimelodid of the Iguaçu River

Assumpção

Makrakis

Silva

et al. 2021

Water

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Steindachneridion melanodermatum, an endemic and endangered species, is the largest catfish in the Lower Iguaçu River basin. Currently, the wild population of this species no longer exists in most of this basin, probably due to the loss of habitat by successive hydroelectric dams. This study evaluated the spatial distribution and abundance of S. melanodermatum in the last free-flowing river stretch of approximately 190 km downstream from the Salto Caxias Dam, upstream of the Iguaçu Falls, as well as some tributaries. Hydroacoustic and fishing campaigns were performed between September 2010 to December 2016 to characterize the preferred habitat. A total of 180 specimens was sampled with higher abundances in a protected area near Iguaçu Falls in the Iguaçu National Park. Twenty-four deep pools were identified with maximum depths ranging from 5 to 25 m: 21 pools were along the main channel of the Iguaçu River, and three pools were in tributaries. Deep pools are preferential habitats for this species, especially the deep pool called Poço Preto (P23) and its surroundings. Conservation strategies are required to protect these habitats and prevent S. melanodermatum from becoming extinct, such as establishing deep pools as ecological sanctuaries, intensifying the inspection of illegal fishing, and maintaining dam-free tributaries.

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“…inhabitants km −2 , mostly concentrated along the river courses (UNEP, 2010). Uranium and manganese mining activity is reported in the Southern Upper Ogooué area and future dam development may potentially affect river connectivity (Cutler et al, 2020). However, overall the contemporary anthropogenic influence on the Ogooué River system can be assumed as insignificant in terms of chemistry, water flow, and sediment fluxes.…”

Section: Study Areamentioning

confidence: 99%

Contrasted Chemical Weathering Rates in Cratonic Basins: The Ogooué and Mbei Rivers, Western Central Africa

Moquet¹,

Bouchez²,

Braun³

et al. 2021

Front. Water

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Despite the absence of tectonic activity, cratonic environments are characterized by strongly variable, and in places significant, rock weathering rates. This is shown here through an exploration of the weathering rates in two inter-tropical river basins from the Atlantic Central Africa: the Ogooué and Mbei River basins, Gabon. We analyzed the elemental and strontium isotope composition of 24 water samples collected throughout these basins. Based on the determination of the major element sources we estimate that the Ogooué and Mbei rivers total dissolved solids (TDS) mainly derive from silicate chemical weathering. The chemical composition of the dissolved load and the area-normalized solute fluxes at the outlet of the Ogooué are similar to those of other West African rivers (e.g., Niger, Nyong, or Congo). However, chemical weathering rates (TZsil+ rate expressed as the release rate of the sum of cations by silicate chemical weathering) span the entire range of chemical weathering intensities hitherto recorded in worldwide cratonic environments. In the Ogooué-Mbei systems, three regions can be distinguished: (i) the Eastern sub-basins draining the Plateaux Batéké underlain by quartz-rich sandstones exhibit the lowest TZsil+ rates, (ii) the Northern sub-basins and the Mbei sub-basins, which drain the southern edge of the tectonically quiescent South Cameroon Plateau, show intermediate TZsil+ rates and (iii) the Southern sub-basins characterized by steeper slopes record the highest TZsil+ rates. In region (ii), higher DOC concentrations are associated with enrichment of elements expected to form insoluble hydrolysates in natural waters (e.g., Fe, Al, Th, REEs) suggesting enhanced transport of these elements in the colloidal phase. In region (iii), we suggest that a combination of mantle-induced dynamic uplift and lithospheric destabilization affecting the rim of the Congo Cuvette induces slow base level lowering thereby enhancing soil erosion, exhumation of fresh primary minerals, and thus weathering rates. The study points out that erosion of lateritic covers in cratonic areas can significantly enhance chemical weathering rates by bringing fresh minerals in contact with meteoric water. The heterogeneity of weathering rates amongst cratonic regions thus need to be considered for reconstructing the global, long-term carbon cycle and its control on Earth climate.

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Habitat loss due to dam development may affect the distribution of marine‐associated fishes in Gabon, Africa

Cited by 8 publications

References 29 publications

Living on the edge: Reservoirs facilitate enhanced interactions among generalist and rheophilic fish species in tributaries

Living on the edge: Reservoirs facilitate enhanced interactions among generalist and rheophilic fish species in tributaries

Deep Pools: Ecological Sanctuaries for Steindachneridion melanodermatum, a Large Endemic and Endangered Pimelodid of the Iguaçu River

Contrasted Chemical Weathering Rates in Cratonic Basins: The Ogooué and Mbei Rivers, Western Central Africa

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