Connectivity in a Dryland River: Short-Term Aquatic Microinvertebrate Recruitment Following Floodplain Inundation

Jenkins, Kim; Boulton, Andrew J.

doi:10.1890/02-0326

Cited by 159 publications

(152 citation statements)

References 43 publications

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“…"the ease with which organisms, matter or energy transverse ecotones between adjacent ecological units" (Ward et al 1999). In riverine systems, water-mediated or hydrological connectivity is thought to be key for the persistence of aquatic biota (Jenkins and Boulton 2003), including fish, in both temperate (Fullerton et al 2010) and tropical systems (Pains da Silva et al 2010). Science-based fisheries management advice has largely failed to deliver even in biologically "simple", single-species, single-type, temperate-zone fisheries (Bayley 1988), as stocks have continued to collapse, often because the political will to fully implement the advice has been a stumbling block (Pauly et al 2002).…”

Section: Introductionmentioning

confidence: 99%

To connect or not to connect? Floods, fisheries and livelihoods in the Lower Rufiji floodplain lakes, Tanzania

Hamerlynck

Duvail²,

Vandepitte

et al. 2011

Hydrological Sciences Journal

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For seven years, village-based recorders monitored fish catches and water levels in seven floodplainassociated lakes of the Lower Rufiji, Tanzania. The lakes differ in the number of days and volume of inflows from the river, and thus provide a natural experiment to explore the links between catch composition, income per hour of fishing (IPHF) and hydrological connectivity, and to analyse the response of the users. The fishers adapt their fishing mode and equipment to achieve a rather constant IPHF of between 0.2 and 0.8 US$/fisher/hour. In situations of low connectivity, during a series of drought years, the less well-connected lakes lost many species and became a virtual monoculture of Oreochromis urolepis. Only in one extreme case was average fish size significantly reduced, indicating a high fishing pressure. Catch was therefore highly resilient to shifts toward illegal, non-selective and active fishing techniques. Fish diversity and lake productivity were quickly re-established when the larger lakes reconnected. The potential impacts of changes in the flood hydrograph (through dams, increased abstraction or climate/land-use changes) are assessed, and management options discussed. La taille moyenne des poissons a été significativement réduite dans un seul cas extrême, montrant ainsi la forte résilience des captures au changement vers des engins de pêche illégaux et non sélectifs et aux techniques de pêche active. La diversité halieutique et la productivité des lacs sont rapidement restaurées quand les plus grands lacs se reconnectent. Les impacts potentiels de modifications de l'hydrogramme de crue (par des barrages, des prélèvements additionnels et des changements climatiques/changements de l'utilisation des sols) sont évalués et des options de gestion sont évoquées.

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Section: Introductionmentioning

confidence: 99%

To connect or not to connect? Floods, fisheries and livelihoods in the Lower Rufiji floodplain lakes, Tanzania

Hamerlynck

Duvail²,

Vandepitte

et al. 2011

Hydrological Sciences Journal

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“…Damming is probably one of the greatest stressors affecting the integrity of running waters (Heinz Center 2002;Garcia de Leaniz 2008), because it can interfere or even stop the transport of sediment and nutrients along waterways and eventually disturb ecological connectivity, which underpins the transfer of materials and products of ecological functions and processes (Jenkins and Boulton 2003). Additionally, impounded waters can trigger important changes in the composition of stream fauna, favoring lentic over lotic species (Raymond 1979;Lewis 2001;Shao et al 2007;Zhou et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Impacts of cascade run-of-river dams on benthic diatoms in the Xiangxi River, China

Tang

et al. 2009

Aquat. Sci.

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The ecological effects of small run-of-river dams on aquatic ecosystems are poorly understood, especially on downstream benthic algal communities. We examined impacts of such dams on the benthic diatom community at a regional scale in the Xiangxi River, China. A total of 90 sites were visited, which were divided into five habitats (H1-H5) according to impact extent of each dam. Using partial least squares (PLS) modeling, we developed two predictive models (diatom species richness and total diatom density) based on environmental variables of an unregulated habitat (H1). These models were then used to predict species richness and total densities at impacted habitats (H2-H5) and residuals, i.e. the differences between observed and predicted values, were used to evaluate impact strength of flow regulation. Significant impacts of flow regulation on diatom species richness were detected at three impacted habitats (H3-H5), where observed species richness were significantly higher-70.6, 63.9 and 46.6%, respectively-than predicted values. Then, possible mechanisms for observed impacts were discussed. Further research is necessary to address the potential negative impacts of cascade run-of-river dams on other aquatic organisms in different seasons, and to explore more appropriate mechanisms for such impacts, which may lead to sustainable management strategies and help to determine the optimal ecological water requirement for the Xiangxi River.

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“…Ecological connectivity underpins the transfer of materials and products of ecological functions and processes. In aquatic ecosystems, the connectivity is mediated by flows and hydrological linkages (JENKINS and BOULTON, 2003). The flow regime is probably one of the most important factors associated with the abundance of riverine zooplankton (KOBAYASHI et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Impacts of a Small Dam on Riverine Zooplankton

Zhou

Tang

et al. 2008

International Review of Hydrobiology

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In order to explore the temporal impacts of a small dam on riverine zooplankton, monthly samples were conducted from November 2005 to June 2006 in a reach of Xiangxi River, China, which is affected by a small hydropower plant. A total of 56 taxa of zooplankton were recorded during the study and rotifers were the most abundant group, accounting for 97% of total taxa, while the others were copepod nauplii and copepod adults. This study indicated that: (1) the small dam in the Xiangxi River study area created distinct physical and ecological conditions relative to free-flowing lotic reaches despite the constrained channel and small size of the dam; (2) the existence of the plant's small dam had a significant effect on the zooplankton community. In long periods of drought or dry seasons the effect of the dam on potamoplankton was more pronounced (e.g., November, February, March, and May). But the downfall or the connectivity of channel appeared to decrease the effect of small hydropower plants on riverine zooplankton (e.g., April). The present observation underscores the need for additional studies that provide more basic data on riverine zooplankton communities and quantify ecological responses to dam construction over longer time spans. IntroductionZooplankton are commonly referred to as 'passive drifters' based on the accepted notion that they are unable to swim against water currents and are thus transported passively in the horizontal plane by the flow field (WIAFE and FRID, 1996). In comparison to lentic systems, much less is known about the factors structuring zooplankton communities in lotic systems (streams and rivers) (JACK and THORP, 2002). Possible factors regulating plankton biomass in rivers may be physical (light), chemical (nutrient concentrations), hydrological, and biotic. The main factors regulating zooplankton biomass or abundance in lotic water are hydrological factors such as discharge or water residence time and suspended sediment (BASU and PICK, 1996;THORP and CASPER, 2003). Plankton in rivers is only important when residence time allows enough time for growth and reproduction (LAIR and REYES-MARCHANT, 1997). However, several studies suggest that zooplankton in river systems occupy an important status in food webs, contributing to secondary production and enabling flow of energy from algal primary producers to higher trophic levels (e.g., MWEBAZA-NDAWULA et al., 2005 All parts of a river ecosystem are inter-connected. Any disturbance to one part will create a greater or lesser response over much of the system. For instance, an in-channel dam can disrupt the river's natural course and flow, alter the water temperature, redirect the river channel, stop the migration of fish to spawning grounds, cut the circulation of organic matter and nutrients, increase the fragmentation of habitat with associated isolation of populations (WINSTON et al., 1991), and ultimately disrupt the composition of the river continuity. Ecological connectivity underpins the transfer of materials and products of e...

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Connectivity in a Dryland River: Short-Term Aquatic Microinvertebrate Recruitment Following Floodplain Inundation

Cited by 159 publications

References 43 publications

To connect or not to connect? Floods, fisheries and livelihoods in the Lower Rufiji floodplain lakes, Tanzania

To connect or not to connect? Floods, fisheries and livelihoods in the Lower Rufiji floodplain lakes, Tanzania

Impacts of cascade run-of-river dams on benthic diatoms in the Xiangxi River, China

Impacts of a Small Dam on Riverine Zooplankton

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