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Showing papers in "Lakes and Reservoirs: Research and Management in 2017"


Journal ArticleDOI
TL;DR: Nile perch were secretly introduced into Lake Victoria in the 1950s, and officially in the 1960s, amid unresolved controversy as mentioned in this paper, with the view that the introduction would improve fisheries production and sport fishing.
Abstract: Nile perch were secretly introduced into Lake Victoria in the 1950s, and officially in the 1960s, amid unresolved controversy. Proponents were of the view that the introduction would improve fisheries production and sport fishing. Although the former objective was achieved, the side effects were dire, including extinction of many native species, especially the ecologically important haplochromines, because of predation. The introduction also changed the habitat, trophic dynamics and water clarity. The change in water clarity is thought to be responsible for hybridization of haplochromines, further contributing to the loss of species diversity among cichlids. The establishment and expansion of the Nile perch also altered the fishery and socio‐economic settings characterizing the lake. A local economy which, until the early 1980s, was based on native fish species has been replaced by an export‐oriented exotic fish processing industry that destroyed the once‐cherished traditional resource. Other socio‐economic issues associated with Nile perch include the high HIV/AIDS prevalence among fishers, and border conflicts attributable to the migratory and transboundary nature of the fishery resource. Conservation measures for the fishery should include establishment of co‐management units that have so far registered both successes and challenges. Other efforts include establishment of the Nile perch Fisheries Management Plans that focus on curbing overfishing and eradicating illegal fishing.

26 citations


Journal ArticleDOI
TL;DR: In this paper, the authors evaluated the use of changes in pollution indicators in Lake Victoria, Kenya, as a decision support tool for fisheries management and productivity, and indicated a declining trend of ecological integrity in the Winam Gulf, compared with the open waters of Lake Victoria.
Abstract: Monitoring of aquatic pollution is important for ascertaining the relationship between fisheries and the general ecosystem health of a lake. This study evaluated the use of changes in pollution indicators in Lake Victoria, Kenya, as a decision support tool for fisheries management and productivity. Principal component analysis (PCA; R2 ≥ 0.5, P < 0.05) of physical and chemical parameters delineated sampling sites into ecological cluster zones consisting of the inner gulf (C1), mid-gulf (C2) and open lake (C3). Test results for lead (Pb) and mercury (Hg) levels in the Nile perch tissues were found to be compliant with EU standards. The inner and mid-gulfs of the Winam Gulf had high levels of total (1818.8 ± 102–1937.78 ± 94 cfu 100 mL−1) and faecal (390 ± 21 cfu 100 mL−1) coliforms attributable to urban sewage and industrial effluents exceeded WHO standards. Similarly, Winam Gulf was more polluted than the open lake, with higher total phosphorus and nitrogen concentrations, turbidity levels and electrical conductivity. Low phytoplankton biovolume and a low number of macroinvertebrates genera, and high zooplankton densities and pollution-tolerant catfishes (e.g., Schilbe victoriae; Clarias gariepinus) were observed in Winam Gulf. Faecal coliforms and dissolved oxygen influenced the abundance of tolerant fish species (e.g., S. victoriae) in the lake. This study indicated a declining trend of ecological integrity in the Winam Gulf, compared with the open waters of Lake Victoria. An integrated management approach directed to minimizing pollution levels, especially in the Winam Gulf, is recommended to enhance fishery production.

23 citations


Journal ArticleDOI
TL;DR: A bathymetric survey was conducted in November 2014 for a period of 10 days, using an echo sounder of 200-kHz single beam, and the survey results indicated an annual average sediment deposition of 3.8 m3 as discussed by the authors.
Abstract: The Dokan Reservoir dam is a concrete cylindrical arch with gravity abutments, located on the Lesser Zab River about 60 km from the city of Sulaimani in north-eastern Iraq. A bathymetric survey was conducted in November 2014 for a period of 10 days, using an echo sounder of 200-kHz single beam. The survey results indicated an annual average sediment deposition of 3.8 million m3. Thirty-two sediment samples were collected from the reservoir bed. The ratio of gravel, sand, silt and clay was 15:14:48:23, respectively. The reservoir bed is covered mainly with silt. The sediments are composed of silty clay (77.6%), silty sandy clay (10%), sandy gravely silty clay (1.2%) and gravely sandy silty clay (1%).

15 citations



Journal ArticleDOI
TL;DR: Evaluated plankton composition, abundance and biomass in Shirati Bay revealed that cyanophyta and Bacillariophyta are the dominant phytoplankton, whereas cyclopoids dominate the zooplankon species in the bay.
Abstract: Shirati Bay is among the important breeding and nursery sites for major fish species in Lake Victoria. Weekly samplings were conducted to assess the temporal patterns in phytoplankton, zooplankton and fish composition, abundance and biomass in relation to prevailing water quality parameters. The study also determined the influences of plankton dynamics and water quality on the fish catch composition and biomass. It was hypothesized that temporal patterns in the composition, abundance and biomass in the plankton in the bay are controlled by water quality parameters that, in turn, affect the composition and biomass of fish catches. The phytoplankton comprised mainly cyanophytes and bacillariophytes, while the zooplankton were dominated by copepods. The heavy rain season exhibited a significantly higher plankton abundance and biomass than the dry season. The plankton abundances in both seasons exhibited significant positive correlations with water temperature and transparency. The phytoplankton community was controlled by calanoid and cyclopoid species. At higher trophic levels, Lates niloticus juveniles, Oreochromis niloticus juveniles and haplochromines controlled Cladocera and Cyclopoid copepods, while Tilapia rendalli juveniles controlled the Rotifera. This study revealed that Cyanophyta and Bacillariophyta are the dominant phytoplankton, whereas cyclopoids dominate the zooplankton species in the bay. These dominant plankton groups are partly controlled by rainfall, water temperature and transparency. Fish biomass, zooplankton and phytoplankton exhibit a typical predator–prey inverse relationship. Thus, evaluation of the plankton composition, abundance and biomass should be mandatory during fisheries stock assessments to effectively manage the fishery resources in the bay.

9 citations



Journal ArticleDOI
TL;DR: In this paper, the sediment quality of the Akkulam-Veli (AV) Lake system was assessed by combining the available guidelines to formulate two new approaches in this study, and the results showed that AV Lake is highly polluted with respect to chromium (Cr), nickel (Ni) and lead (Pb), while arsenic (As) and cadmium (Cd) are non-polluting with a negligible potential for adverse effects.
Abstract: Sediments are often reservoirs of contaminants in aquatic waterbodies, and their quality can be an indicator of the health of their ecosystems. Heavy metal pollution in sediments is highly significant because of their persistent and bioaccumulative nature. In this regard, sediment quality guidelines (SQG) are useful for categorizing sediment quality with respect to the contaminant level in them. An attempt was made in this study to assess the sediment quality of the Akkulam-Veli (AV) Lake system on the basis of guidelines that incorporate assessment scales that differ in their approaches. Some link threshold levels of heavy metal concentrations on the basis of their likelihood to cause adverse effects, while others classify the sediment concentration ranges that correspond to the degrees of toxicity caused by them. The sediment quality of the study area was assessed by combining the available guidelines to formulate two new approaches in this study. Based on this approach, AV Lake is highly polluted with respect to chromium (Cr), nickel (Ni) and lead (Pb), while arsenic (As) and cadmium (Cd) are non-polluting with a negligible potential for adverse effects.

8 citations


Journal ArticleDOI
TL;DR: In this paper, a study was carried out in the branches of the Sao Francisco Falso, Sao Francisco Verdadeiro and Ocoi rivers in the Parana Basin draining to Itaipu Reservoir using the Dillon and Rigler eutrophication model.
Abstract: Actions facilitating the reconciliation of multiple uses of a reservoir with electric power generation should be implemented so as to avoid conflicts and support the best development of the water resource In view of the fish production potential existing in Itaipu Reservoir, the objective of this study was to select areas considered adequate for establishing aquaculture parks by means of integrated and ordered planning that respect the carrying capacity of the environment This study was carried out in the branches of the Sao Francisco Falso, Sao Francisco Verdadeiro and Ocoi rivers in the Parana Basin draining to Itaipu Reservoir Using the Dillon and Rigler eutrophication model, the carrying capacity and estimated production were 2537, 2554 and 1569 t yr−1 in the respective branches The percentages of occupation of each aquaculture park, taking into consideration the maximum area of dilution and safety level for the reservoir operation, were 046%, 048% and 009% for the three branches, respectively It was concluded that the aquaculture activity could be promoted in a sustainable manner under constant monitoring of water quality and production parameters in accordance with a management programme, combined with planning of these aquaculture areas in a manner that ensured the application of physical limits for the carrying capacity established in this study

7 citations


Journal ArticleDOI
TL;DR: The results of the present study generally suggest the phytoplankton composition and biomass in Lake Shala exhibited muted seasonal changes, despite the environmental perturbations, probably because of the lake's high buffering capacity against allochthonous impacts because of its voluminous nature.
Abstract: Although soda lakes are valuable, sensitive aquatic resources where phytoplankton play a decisive role for the entire ecological functions, they are among the least-studied ecosystems. Seasonal variations in phytoplankton composition, abundance and biomass in relation to some environmental parameters of the little known, deep, large, volcanic and saline–alkaline Lake Shala were investigated over an annual cycle. The lake phytoplankton community consisted of relatively diverse taxa (23) belonging to Bacillariophyceae, Cryptophyta, Cyanoprokaryota and Dinophyta. Bacillariophyceae and Cryptophyta were the dominant groups throughout the annual cycle, accounting for about 57% and 22% of the total number of species, and 28% and 69% of the total abundance of the phytoplankton community, respectively. Cryptomonas spp. were most abundant throughout nearly all months, contributing about 59%–95% of total phytoplankton abundance, followed by Thalassiosira sp. (1%–35%). The chlorophyll-a concentration, as a proxy for algal biomass, was generally low (mean 17 μg L−1), exhibiting only small seasonal variation. The strong, inverse relation of chlorophyll-a with water transparency (r = −0.69; n = 11) and the persistent dominance of species adapted to low-light conditions and mixing suggest the overriding importance of these factors in controlling the lake's phytoplankton. The results of the present study generally suggest the phytoplankton composition and biomass in Lake Shala exhibited muted seasonal changes, despite the environmental perturbations, probably because of the lake's high buffering capacity against allochthonous impacts because of its voluminous nature.

7 citations



Journal ArticleDOI
TL;DR: In this paper, the authors assess the implementation of IWRM in Malawi to the present time, in relation to the five priority areas the country's Integrated Water Resources Management/Water Efficiency (IWRM/WE) Plan (2008-2012) sought to address, as well as the potential benefits of infusing Integrated Lake Basin Management (ILBM) in this approach.
Abstract: Many countries, including Malawi, are implementing integrated approaches for the development, management and use of water and other natural resources. Integrated Water Resources Management (IWRM) is, arguably, one approach considered helpful in addressing water issues effectively and sustainably. This study assesses the implementation of IWRM in Malawi to the present time, in relation to the five priority areas the country's Integrated Water Resources Management/Water Efficiency (IWRM/WE) Plan (2008–2012) sought to address, as well as the potential benefits of infusing Integrated Lake Basin Management (ILBM) in this approach. Document reviews, key informant interviews, questionnaire surveys and site visits were the employed methods in this analysis. Considering the significant importance of lakes in the country, this study, through application of the strengths, weaknesses, opportunities and threats framework, provides insight on how lake basin management issues can best be incorporated within the existing IWRM-based framework to promote the management and utilization of lakes for sustainable use. While acknowledging the relevance of a holistic approach, the study highlights the importance for the country to ensure that its development agenda is not negatively affected in the course of implementing IWRM.

Journal ArticleDOI
TL;DR: A lake-wide survey in Lake Chivero, Zimbabwe, was performed to examine the spatial distribution of three sediment grain sizes; determine their nutrient concentrations; and analyse the relationships between the measured surface sediment variables in the three sediment seed sizes.
Abstract: A lake-wide survey in Lake Chivero, Zimbabwe, was performed to (i) examine the spatial distribution of three sediment grain sizes; (ii) determine their nutrient concentrations; and (iii) analyse the relationships between the measured surface sediment variables in the three sediment grain sizes. The results of this study indicated sand, silt and mud sediments occupied about 24, 22 and 54%, respectively, of the lake area. All the measured physicochemical variables varied significantly among the three sediment grain sizes (P < 0.05, anova). High values for pH, dissolved oxygen and NO3 were observed in the sand sediments, while water depth, electrical conductivity, soluble reactive phosphorus, NH4, total phosphorus, total nitrogen and total organic carbon were observed in the mud sediments. In the silt sediments, most measured variables showed intermediate values. Intervariable correlation indicated varied correlation patterns among the three sediment grain sizes. Information generated in this study is essential for an accurate delineation of the spatial extent of nutrient and contaminant distribution in the sediment of Lake Chivero and will facilitate the ability of lake managers to derive a comprehensive nutrient budget of the lake as a means of establishing realistic target conditions for lake restoration.


Journal ArticleDOI
TL;DR: In this paper, a case of common pool water resource management, including consideration of the interference of a regulator, is considered, and the game among players is investigated in terms of two static and dynamic game methods.
Abstract: An increased need for water, combined with a scarcity of water resources, has resulted in serious challenges regarding water resource management. Those issues have always been a major concern of most research regarding the management and operation of water resources. Various qualitative and quantitative methods, Game Theory (GT) being an example, have been proposed for managing common pool water resources. This study adopts GT to address a case of common pool water resource management, including consideration of the interference of a regulator. Urmia lake in north-western Iran was chosen as an illustration of a common source of water shared between two provinces acting as littoral stakeholders to the lake. Due to a non-cooperative behaviour of the stakeholders, the lake is most likely to dry up. To change the game situation, a regulator was inserted into the game as a third player. The game among players is investigated in terms of two static and dynamic game methods. Two strategies are defined for each player. The equilibrium point will be achieved according to the strategies adopted by the players. For static games, a low-level equilibrium under non-cooperation conditions is obtained. Dynamic games among players are more likely to occur, rather than static games. The equilibrium of high-level productivity will be obtained under cooperative conditions among the players.

Journal ArticleDOI
TL;DR: In this article, the authors focus on the self-sustainability of a water body, based on the water budget approach, and taking into account various hydroclimatical and geological factors in the study area.
Abstract: Studies addressing the self-sustainability of water bodies are crucial from the perspective of sustainable water resources management. An artificial water body is vulnerable to drastic water level changes resulting from various hydroclimatical and geological factors. It is incumbent therefore to rigorously investigate the effects of these factors in order to assess the response of the water body, consequent to a wide range of scenarios. This study focuses on the self-sustainability of a water body, based on the water budget approach, and taking into account various hydroclimatical and geological factors in the study area. As the available evaporation data shared a very short (~2 years) common time frame with the other variables, evaporation was modelled using regression and artificial neural network models. The study results indicated the water body would be self-sustainable under the extreme climatical and hydrological conditions considered. While seepage exhibited substantial impacts on the storage of the water body, evaporation was found to have only marginal impacts.


Journal ArticleDOI
TL;DR: Both the 5 and 7 cm gillnets were found to be inappropriate for use in the reservoir and their use should be discouraged to protect juvenile fish so that the sustainable exploitation and conservation of fish species in this multispecies fishery can be achieved.
Abstract: Gillnet selectivity is crucial for the effective and sustainable management of fisheries. However, there is inadequate information on gillnet selectivity for commercially important species in Tono Reservoir. To facilitate the sustainable exploitation of fish species, this study was conducted to estimate the selectivity parameters of commonly used monofilament gillnets for commercially important fish species in Tono Reservoir from January 2015 to June 2016. Two common nylon monofilament gillnets used by fishermen in Tono Reservoir with stretched mesh sizes 5 and 7 cm and equal dimensions were placed in the same fishing area and retrieved within 12 h. The fish catches were assessed, and selectivity parameters for Sarotherodon galilaeus, Oreochromis niloticus, Coptodon zillii, Clarias gariepinus and Auchenoglanis occidentalis were estimated using the Holt model. The catch per unit effort of the two gillnets exhibited no significant difference. The optimum total lengths of capture of four fish species excluding C. zillii ranged from 13.53 to 25.43 cm for the 5 cm gillnet, and 18.95 to 35.60 cm for the 7 cm gillnet. Common selection factors varied from 2.71 to 5.09. The mean total length at first sexual maturity for all five fish species ranged from 8.60 to 28.86 cm. Both the 5 and 7 cm gillnets were found to be inappropriate for use in the reservoir. Accordingly, their use should be discouraged to protect juvenile fish so that the sustainable exploitation and conservation of fish species in this multispecies fishery can be achieved.


Journal ArticleDOI
TL;DR: Nile perch is a predatory fish, feeding mainly on C. nilotica, haplochromines, tilapia, Nile perch and other fish materials.
Abstract: A total of 289 fish were analysed in this study, with Caradina nilotica (44%) being the dominant food item in their diet, while tilapia (8%) contributed the least. Haplochromines, unidentified fish prey and juvenile Nile perch also were observed. An ontogenic shift was observed, with C. nilotica contributing highest (61.1%) of the diet of fingerlings, but decreasing to 21% in the diet of adults. Nile perch contributed 35.7% of the diet in the adults and 8.1% in the fingerlings. This study indicates Nile perch is a predatory fish, feeding mainly on C. nilotica, haplochromines, tilapia, Nile perch and other fish materials.

Journal ArticleDOI
TL;DR: In this article, the authors focus on determining how many samples are needed to effectively assess the species richness of a community, and they find that using a single sampling unit per lake would not be sufficient to accurately estimate their diversity.
Abstract: This study focuses on determining how many samples are needed to effectively assess the species richness of a community. Zooplankton samples at 40 sampling sites distributed among four lakes in the floodplain of the middle Araguaia River (Central-West region of Brazil) were evaluated to determine the effect of the accumulation of collecting points by lake on species richness estimates. The results indicated the zooplankton community has high spatial heterogeneity. Thus, using a single sampling unit per lake would not be sufficient to accurately estimate their diversity (i.e. the zooplankton composition in these cases would be represented mainly by abundant species). Sampling designs that include a minimum of seven sampling sites in each lake are needed to record 70% of the total species richness. It is recommended, therefore, that researchers use a larger number of sampling sites per lake or, alternatively, that the water obtained and filtered through plankton nets is extracted from a wide area and in different lake compartments, rather than from a single site.

Journal ArticleDOI
TL;DR: In this study, it appears the lakes were perceived by those who abandon their pets as the most ecologically suitable habitats among other pond types to accommodate the different species of turtles.
Abstract: The patterns of the occurrence and distribution of alien freshwater turtle species in an urban pond archipelago (Rome, Italy) were analysed, with the aim of exploring the role of a set of factors (type of ponds, landscape context, size area, distance from the nearest road) with a generalized linear model approach. A total of 311 ponds subdivided in three types (fountains, small basins, lakes) embedded in different landscape contexts (public parks, private parks, urban areas) at differing distances from the nearest road were sampled. Six non-native freshwater turtle species in 31 sites were recorded (9.97%). Lakes exhibited the highest occurrence rates of alien freshwater turtles, compared to small basins and fountains. Freshwater turtle species in urbanized areas were only observed in parks (both public and private). In both the public and private parks, the lakes exhibited the highest percentage of occupied sites, with fountains being the lowest. A direct and significant relationship was observed between pond size and species richness. The distance from the nearest road did not appear to affect species richness. A first interpretation of the data from this study facilitated the postulation of two a posteriori hypotheses that should be tested, as follows: (i) the causal process of turtle release is random, and the rate of extinction (and recapture) is higher in smaller ponds, thus producing the observed pattern; and (ii) the turtle release is not random, and people actively select the ponds they consider more suitable for their pet animals. In this study, it appears the lakes were perceived by those who abandon their pets as the most ecologically suitable habitats among other pond types to accommodate the different species of turtles. Knowledge of people's attitudes in regard to releasing pet animals also might assist managers of public green spaces to develop strategies aimed to preserve local biodiversity, and to educate the public about the conservation issue represented by the alien species.

Journal ArticleDOI
TL;DR: The shift of salinity tolerant ranges in three species of ciliates Paramecium caudatum, P. primaurelia and P. jenningsi was studied in waters containing a composition of salts resembling those in the Aral Sea, and the results indicate that the salt values of tolerant ranges are increasing in water with theAral Sea composition.
Abstract: The shift of salinity tolerant ranges in three species of ciliates Paramecium caudatum, P. primaurelia and P. jenningsi was studied in waters containing a composition of salts resembling those in the Aral Sea, in comparison with composition of salts in marine waters. The results indicate that the salt values of tolerant ranges are increasing in water with the Aral Sea composition. The ratio among values of tolerant ranges is described by a linear function. A similar ratio connecting the same tolerant ranges exists in ciliates, but leads to reliable values of tolerant ranges when expressed in terms of chlorine concentration. Thus, the connection between the tolerances of aquatic organisms obtained for water of marine composition and water of continental composition might be described by the equation Sm=αβ·Sk, where Sm = tolerance of organisms in marine water, whereas Sk = tolerance of organisms in continental saline water. The term α indicates the portion of chlorine ion continental saline water, while β indicates the portion in marine water.



Journal ArticleDOI
TL;DR: In this article, the authors evaluate the risks associated with nutrient and heavy metal pollution in the water and sediments of Kouris Reservoir in Cyprus, and to recommend applicable measures to alleviate them.
Abstract: The objective of this study was to evaluate the risks associated with nutrient and heavy metal pollution in the water and sediments of Kouris Reservoir in Cyprus, and to recommend applicable measures to alleviate them. The reservoir drainage area contains various historic abandoned copper mines existing in an ophiolite geological substrate. Kouris Reservoir water is classified as oligotrophic to mesotrophic, with phosphorus being the limiting factor for algae growth. The thermal stratification of the reservoir enhances anoxic conditions in the reservoir hypolimnion, initiating phosphorus release back into the water column from the lake bottom sediments. The increased phosphorus release, in combination with increased water temperatures during the summer months (i.e. reaching 27 °C in August), may be the key factors enhancing the growth of microbial communities and cyanobacteria blooms. The sediment of Kouris Reservoir is classified as ‘low risk’ on the basis of the Ecological Risk Index scheme, in contrast to the Geoaccumulation Index, which indicates a moderate degree of contamination for chromium (Cr), nickel (Ni) and copper (Cu), and a high degree for lead (Pb). Heavy metals are strongly bound to the sediment matrix at pH values between 7 and 9, but can be released back into the water column at potential acid pH values. In addition, the sediments exhibit a high copper and chromium absorption affinity under current water quality conditions in the reservoir, as shown by batch absorption experiments. The experimental results suggest dredging of the reservoir sediment, and its subsequent dumping of the sediments near influent streams, would have adverse effects on the environment in the event of acid rain or other environmental changes that might acidify the sediment.

Journal ArticleDOI
TL;DR: In this article, the role of local governments in managing and developing the small lakes is analyzed, and the main feature of governance regarding the three lakes is the municipal governments commitment and determination, which is consequential in their development over time.
Abstract: Although many lakes in the Philippines are threatened, the effectiveness of their governance has not received sufficient attention to date This predicament is most severe in regard to small lakes as their localized governance has least been given consideration over the years Predicated on this observation, this study explores the local governance of three small lakes (Gunao Lake; Tikub Lake; Dagatan Lake) situated between the Mount Banahaw–San Cristobal and Mount Malepunyo area Specifically, it analyses the role of local governments in managing and developing the small lakes Using data from interviews, observations and the few existing documents on these lakes, this study contends that the main feature of governance regarding the three lakes is the Municipal Governments’ commitment and determination, which is consequential in their development over time For Gunao Lake, the failure of the Municipal Government of Dolores to link the development of the lake with the tourism agenda in the Mount Banahaw area has resulted in its lack of tourism development For Tikub Lake, the consistent push of the Municipal Government of Tiaong for its tourism agenda is key in the incremental improvement and preservation of the lake For Dagatan Lake, the persistence of the Municipal Government of San Antonio in pursuing the restoration project and searching for a patron to finance the endeavour is crucial in the revival of the lake Overall, this study highlights the distinct praxis of local governance regarding each of these small lakes, extends scholarship in regard to lake governance and offers a broad template for managing the many existing small lakes in the country

Journal ArticleDOI
TL;DR: Canonical correspondence analysis (CCA), in conjunction with large differences in eigenvalues between constrained and unconstrained ordinations, suggest that unmeasured environmental variables are also important in structuring cladoceran assemblages.
Abstract: The potential of using surface-sediment assemblages of Cladocera as bioindicators for reservoirs in Sri Lanka was assessed for their subfossil remains, along with contemporary physical and chemical measurements from each reservoir. The reservoirs span five climatic regions, from extremely arid environments to tropical montane forests, as well as three orders of magnitude changes in many physical and chemical variables. In total, although the remains of 39 Cladocera taxa from 21 genera were identified, only 31 taxa from 37 sites were present at sufficiently high abundances to assess their relation to measured environmental variables. Canonical correspondence analysis (CCA) identified surface area, maximum depth and chloride as the three most important measured environmental variables that could account for the variation in the cladoceran assemblages. Taxa such as Chydorus sphaericus, Alona aff. verrucosa and Leydigia acanthocercoides were more abundant in generally deeper, larger reservoirs, whereas Alonella excisa, Euryalona orientalis, Notoalona globulosa and Chydorus eurynotus were more abundant in shallow smaller reservoirs. Although there was a strong separation between climatic zones in terms of factors related to specific conductance, this factor only appears marginally important in separating cladoceran assemblages. Quantitative inference models developed to assess the strength of inferring environmental variables using partial least squares regression and calibration were all relatively weak, with jackknifed coefficient of determination values of 0.40, 0.28 and 0.27 for surface area, maximum depth and chloride, respectively. These results, in conjunction with large differences in eigenvalues between constrained and unconstrained ordinations, suggest that unmeasured environmental variables are also important in structuring cladoceran assemblages.

Journal ArticleDOI
TL;DR: It is clear that the zooplankton communities are depleting, along with the mangrove vegetation, because of the shallowness and unsuitable environmental conditions of the water bodies attributable to anthropogenic stresses.
Abstract: The diversity, abundance and community structure of mesozooplankton from the hydrographically differing mangrove habitats in Cochin, Kerala (India), were investigated. Eleven zooplankton groups were identified, with calanoid copepods (62%) comprising the predominant population, followed by crustacean nauplii (22%) and mysids (12%). Nitrogen limiting (N: P ratio 5.13 ± 7.03) with a mixo‐mesohaline salinity (8.96 ± 3 psu) and relatively low temperatures (30.28 ± 0.9 °C) was a characteristic feature of the study zones. Non‐metric multidimensional scaling based on Bray–Curtis similarity (PRIMER) analysis revealed there was little variation in the mesozooplankton structure among sampling sites (stress 0.05; ANOSIM test Global R:0.325). BEST analysis indicated that temperature and salinity exhibited the best correlation (ρ = 0.701) with fauna. The results of this study indicated a severe reduction in zooplankton abundance, biomass and diversity. It is clear that the zooplankton communities are depleting, along with the mangrove vegetation, because of the shallowness and unsuitable environmental conditions of the water bodies attributable to anthropogenic stresses.

Journal ArticleDOI
TL;DR: The Pareja Limno-reservoir is currently a successful tourist and recreational aquatic resource, however, the results of this study reveal its recreational and environmental value may be reduced, especially as a constant water level at the maximum capacity of the limno-Reservoir cannot be guaranteed.
Abstract: Large reservoirs in the Mediterranean area exhibit a variety of negative impacts resulting from exploitation of their water, many a result of large water-level fluctuations. Water managers in Spain have implemented various mitigation measures to reduce these negative impacts. One such measure is construction of small dams in the riverine zone of large reservoirs to create a small waterbody with a constant water level (i.e. a ‘limno-reservoir’) to provide the environmental and recreational services that the main reservoir cannot provide due to water-level variations. To this end, the Pareja Limno-reservoir was built in 2006 in a sidearm of the Entrepenas Reservoir (Guadalajara, central Spain). As its environmental sustainability was not assessed prior to construction, however, there are some uncertainties about the ability of the limno-reservoir to provide the expected environmental and recreational services. Accordingly, a multidisciplinary study was conducted on the Pareja Limno-reservoir to shed on its environmental sustainability. This study addressed three relevant issues associated with the limno-reservoir, focusing on water availability, water quality and the risk of sediment filling. This study reviews the research conducted to date, including an integrative discussion that endeavours to address these issues. The Pareja Limno-reservoir is currently a successful tourist and recreational aquatic resource. The results of this study, however, reveal its recreational and environmental value may be reduced, especially as a constant water level at the maximum capacity of the limno-reservoir cannot be guaranteed. The conclusions of this study may be useful for reservoir managers by providing guidelines for assessing the environmental sustainability of limno-reservoirs.

Journal ArticleDOI
TL;DR: The Harike Wetland in Punjab is a Ramsar site and a wetland of national importance as mentioned in this paper, and a study was undertaken to assess the spatiotemporal dynamics of the wetland on the basis of geospatial technology and ground-based studies.
Abstract: The Harike Wetland situated in Punjab is a Ramsar site and a wetland of national importance. The present study was undertaken to assess the spatiotemporal dynamics of the wetland on the basis of geospatial technology and ground-based studies. Landsat images for the years 2002 and 2014 were acquired from the United States Geological Survey and classified digitally to generate landuse/land cover maps involving four classes (water, grassland (including water hyacinth), agriculture, built-up (settlement), barren land). The total area of the Harike Wetland was found to be 8023.68 ha. Water sampling at eleven sites was carried out and evaluated for physicochemical parameters. The water quality at several sampling points was found to be severely degraded. Change detection analysis revealed the submerged area (area under water) and grassland (including water hyacinth) had decreased over the past 12 years, whereas that area under agriculture and built-up land has increased, indicating a shrinkage in the total wetland area. The present study also indicated that the near-infrared band is a good indicator of water quality parameters, as indicated by the significant positive correlation between the near-infrared band and relevant water parameters. Because the wetland is important from both an ecological perspective and economic perspective, regular monitoring is recommended, for which geospatial technology has proven to be very useful.