Man-made lakes in Mediterranean semi-arid climate: the strange case of Dr Deep Lake and Mr Shallow Lake

Naselli-Flores, Luigi

doi:10.1023/b:hydr.0000008550.34409.06

Cited by 122 publications

(93 citation statements)

References 25 publications

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“…These changes, in turn, lead to shifts in phytoplankton attributes (Chellappa et al, 2009;Câmara et al, 2015), which reinforce the use of this community to evaluate the environmental status of these aquatic ecosystems. For example, high concentrations of nutrients, high conductivity and increased phytoplankton biomass could be expected in reservoirs and lakes located in semi-arid regions with reduced water volume (Naselli-Flores, 2003;Bouvy et al, 2003;Mosley et al, 2012;Jirsa et al, 2013). On the other hand, since the reduction of water volume occurs along with intensification in sediment resuspension and turbidity, a negative impact on phytoplankton biomass could also be expected (Braga et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Assessing temporal and spatial variability of phytoplankton composition in a large reservoir in the Brazilian northeastern region under intense drought conditions

et al. 2017

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The present study was carried out in Castanhão Reservoir, a large aquatic system in the Brazilian semi-arid region that serves multiples uses as water drinking supply and intensive fish-cage aquaculture site. In order to understand the effects of environmental conditions on the spatial and temporal variability of the phytoplankton functional groups (FG) and the main 'characterizing taxa', sub-superficial water samples were collected from March 2012 to August 2013, a period distinguished by the continuous drop in reservoir volume due to rainfall shortage. Eighteen functional groups and 102 total phytoplankton taxa were found in the Castanhão reservoir during the study. No significant differences were observed relative to spatial variation of total phytoplankton composition throughout the reservoir (PERMANOVA, P>0.05). On the other hand, according to cluster analysis results, three temporal phases have been identified (Similarity Profile, P<0.05), based on 102 phytoplankton taxa. The 'characterizing taxa' was found using the Similarity Percentage procedure (cut-off 90%), being thus defined as those taxa that contributed the most to the similarity within each temporal phase. Nineteen 'characterizing taxa' described the Castanhão reservoir, with predominance of those typical of mixing and turbidity conditions. Cyanobacteria dominated through the three temporal phases. According to the redundancy analysis, nutrient availability and water transparency were found to influence the phytoplankton temporal dynamics. The phase I (rainy season) was most represented by Planktolyngbya minor/Pl. limnetica (FG=S1), which reached best performance under strongly decreased phosphate-P concentrations and low water transparency. In phase II (dry season), Pseudanabaena sp.1 (FG=?) outcompeted other cyanobacteria probably due the increase in water transparency and decrease in ammonium-N. Finally, in phase III (rainy season) the decrease of water transparency triggered a recovery of shade-adapted cyanobacteria, but at this time mostly represented by Pseudanabaena limnetica (FG=S1). Phase III was also distinctive from the other ones by the highest Nitrate-N and phosphate-P concentrations related to thermocline disruption, which favored an increase in total phytoplankton biomass recorded by the augment of green algae density (FGs=X1, J and F). We concluded that the temporal dynamics of phytoplankton composition was associated to environmental changes in Castanhão Reservoir from 2012 to 2013, which were driven by seasonal climate variation from region (rainy/dry seasons), as well as, by the reduction in reservoir volume that resulted in the disruption of the thermocline, water mixing and an increase in inorganic P and N.

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Section: Introductionmentioning

confidence: 99%

Assessing temporal and spatial variability of phytoplankton composition in a large reservoir in the Brazilian northeastern region under intense drought conditions

et al. 2017

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“…The post-drought phytoplankton response depends strongly on the pre-drought trophic state. In even a mildly eutrophic lake (such as LR), drought can push the phytoplankton assemblage from mixed diversity to one dominated by potentially toxic cyanobacteria (Naselli-Flores, 2003;Baldwin et al, 2006;Lake, 2011).…”

Section: Introductionmentioning

confidence: 99%

Impact of temporary desiccation on the mobility of nutrients and metals from sediments of Loskop Reservoir, Olifants River

Dabrowski

Baldwin

Hill

et al. 2017

WSA

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South Africa is prone to droughts and is heavily dependent on stored water resources. Few studies in South Africa have investigated the impact of drought on water quality when rainfall resumes and reservoir sediments are rewet. Other research has shown that several negative impacts may occur with rewetting, including eutrophication, and acidification with increased metal solubility. In this study, the impact of drying and rewetting sediments on the mobility of nutrients and metals is explored using sediments from Loskop Reservoir. Rarely exposed sediments were collected from three sites, dried at 35°C for 36 days, and then rewet under aerobic conditions. Filtered water samples were collected on Days 1, 2 ,4, 7, 11 and 16 following rewetting, and analysed for , and were compared to reference (non-drought) treatments that were maintained under saturated conditions. Acute toxicity tests were performed using Daphnia magna to establish if toxic effects were associated with changes in water quality following sediment rewetting. Following rewetting, elevated SO 4 2-indicated the mobilisation of acid from sulfide oxidation, with an associated reduction in pH. Nitrification was evident as high quantities of organic N and NH 4 + were initially released, followed by increases in NO 2 -+ NO 3 -. Total P increased, but PO 4 3-reduced. This was attributed to complexes formed between PO 4 3-and Fe (FePO 4 ) and Al (AlPO 4 ). Amounts of Fe and Al released were lower following rewetting due to the formation of relatively immobile (hydr)oxides. In contrast, Mn increased substantially reaching maximum values > 2 300 mg/m 2 (14 000 µg/L). There were no acute toxic effects observed to D. magna. This study highlights the potential for acidification, mobilisation of nutrients, SO 4 2-, and Mn following rewetting of reservoir sediments under aerobic conditions. This information may be incorporated into reservoir and catchment management plans in the form of revised water quality guidelines and a better ability to predict how drought impacts water quality in our stored water resources.

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“…Summer level fluctuations in particular may cause the breakdown of thermal stratification, causing even deep reservoirs to behave like shallow lakes (Naselli-Flores 2003). These effects are enhanced in relatively shallow reservoirs, with strong water uptake and rapid level changes, such as those found in Sicily (Naselli-Flores & Barone 2005).…”

Section: Introductionmentioning

confidence: 99%

A numerical index for evaluating phytoplankton response to changes in nutrient levels in deep mediterranean reservoirs

Marchetto¹,

Padedda²,

Mariani³

et al. 2009

J Limnol

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Man-made lakes in Mediterranean semi-arid climate: the strange case of Dr Deep Lake and Mr Shallow Lake

Cited by 122 publications

References 25 publications

Assessing temporal and spatial variability of phytoplankton composition in a large reservoir in the Brazilian northeastern region under intense drought conditions

Assessing temporal and spatial variability of phytoplankton composition in a large reservoir in the Brazilian northeastern region under intense drought conditions

Impact of temporary desiccation on the mobility of nutrients and metals from sediments of Loskop Reservoir, Olifants River

A numerical index for evaluating phytoplankton response to changes in nutrient levels in deep mediterranean reservoirs

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