Muddy waters: the influence of high suspended-sediment concentration on the diving behaviour of a bimodally respiring freshwater turtle from north-eastern Australia

2016 ◽  
Vol 67 (4) ◽  
pp. 505 ◽  
Author(s):  
Jason R. Schaffer ◽  
Mark Hamann ◽  
Richard Rowe ◽  
Damien W. Burrows
Keyword(s):  
Low Temperature ◽  
Suspended Sediment ◽  
Sediment Concentration ◽  
Dive Duration ◽  
Diving Behaviour ◽  
Freshwater Turtle ◽  
Freshwater Turtles ◽  
Aquatic Respiration ◽  
Eastern Australia ◽  
The Impact

Increased suspended-sediment concentrations (SS) in rivers can affect aquatic respiration in riverine fauna by impairing respiratory function. Bimodally respiring freshwater turtles are likely to be sensitive to changes in SS because increased concentrations may affect their ability to aquatically respire. However, the impact of SS on the diving behaviour of bimodally respiring freshwater turtles has not been formally investigated. To test this, we examined the influence of dissolved oxygen (DO) saturation (25%, 100%) and temperature (17°C, 25°C) on the diving behaviour of Elseya irwini under clear (0mgL–1) and turbid (79mgL–1) conditions. We hypothesised that low temperature and high DO % saturation would increase dive duration and that high SS would negate the effect of DO, decreasing dive duration under highly oxygenated conditions. Our data demonstrated that increased SS significantly reduced mean dive duration by 73% (97.4±10.1min in 0mgL–1 trials v. 26.4±3.2min in 79mgL–1 trials) under conditions of low temperature (17°C) and high DO % saturation (100%) only. Increased SS directly affects the utilisation of DO by this species, so as to extend submergence times (aquatic respiration) under optimal conditions, raising concerns about the effect of SS on the persistence of populations of physiologically specialised freshwater turtles.

scholarly journals Field methods of a near-bed suspended sediment experiment in the Yangtze River, China

2020 ◽  
Vol 13 (21) ◽  
Author(s):  
Caiwen Shu ◽  
Guangming Tan ◽  
Yiwei Lv ◽  
Quanxi Xu
Keyword(s):  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Dynamic Equilibrium ◽  
Water Discharge ◽  
Sediment Concentration ◽  
Common Method ◽  
Sediment Discharge ◽  
Improved Method ◽  
The Common ◽  
The Impact

AbstractUsing experimental data of near-bed suspended sediment concentrations at five typical hydrometric stations of the Three Gorges Reservoir at the early reserving stage, the differences were investigated between the common method and improved method during flood seasons and non-flood seasons. The impact of taking measurements below 0.2 times the water depth on the results was discussed. The results show that the average discharges and velocities at each station calculated by the common method were slightly larger than those calculated by the improved method. Regarding the suspended sediment concentration at each station, the errors in the reservoir and downstream channels in dynamic equilibrium state were small, and the largest errors occurred where the river bed was strongly scoured in the downstream reach below the large dam. There was no significant relationship between water discharge and flow velocity, and the missed measurement phenomenon also occurred. The sediment discharge error was affected by the suspended sediment concentration, implying that errors usually occurred in channels with serious erosion during flood seasons. The correction coefficients (R2) of sediment discharge at each station were given during the experiment, which showed that the sediment discharges at the hydrometric stations where a large amount of sediment transport occurred near the river bottom, needed to be modified. Furthermore, the test methods proposed in this study were applied to calculate the sediment discharges of three rivers, and the results indicate that this method can narrow the gap between bathymetric comparisons and sediment load measurements.

scholarly journals Suspended sediment fluxes in an Indonesian river draining a rainforested basin subject to land cover change

2011 ◽  
Vol 8 (4) ◽  
pp. 7137-7175 ◽  
Author(s):  
F. A. Buschman ◽  
A. J. F. Hoitink ◽  
S. M. de Jong ◽  
P. Hoekstra
Keyword(s):  
Land Cover ◽  
Suspended Sediment ◽  
River Discharge ◽  
Soil Loss ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Sediment Flux ◽  
Sediment Fluxes ◽  
Suspended Sediment Flux ◽  
The Impact

Abstract. Forest clearing for reasons of timber production, open pit mining and the establishment of oil palm plantations generally results in excessively high sediment loads in the tropics. The increasing sediment fluxes pose a threat to coastal marine ecosystems such as coral reefs. This study presents observations of suspended sediment fluxes in the Berau river (Indonesia), which debouches into a coastal ocean that can be considered the preeminent center of coral diversity. The Berau is an example of a small river draining a mountainous, relatively pristine basin that receives abundant rainfall. Flow velocity was measured over a large part of the river width at a station under the influence of tides, using a Horizontal Acoustic Doppler Current Profiler (HADCP). Surrogate measurements of suspended sediment concentration were taken with an Optical Backscatter Sensor (OBS). Tidally averaged suspended sediment concentration increases with river discharge, implying that the tidally averaged suspended sediment flux increases non-linearly with river discharge. Averaged over the 6.5 weeks observations covered by the benchmark survey, the tidally averaged suspended sediment flux was estimated at 2 Mt y−1. Considering the wet conditions during the observation period, this figure may be considered as an upper limit of the yearly averaged flux. This flux is significantly smaller than what could have been expected from the characteristics of the catchment. The consequences of ongoing clearing of rainforest were explored using a plot scale erosion model. When rainforest, which still covered 50–60 % of the basin in 2007, is converted to production land, soil loss is expected to increase with a factor between 10 and 100. If this soil loss is transported seaward as suspended sediment, the increase in suspended sediment flux in the Berau river would impose a severe sediment stress on the global hotspot of coral reef diversity. The impact of land cover changes will largely depend on the degree in which the Berau estuary acts as a sediment trap.

scholarly journals Suspended sediment in lowland rivers – towards identifying the ratios of mineral and organic components and their variation during the year

Geologos ◽  
2021 ◽  
Vol 27 (3) ◽  
pp. 173-180
Author(s):  
Katarzyna Skolasińska
Keyword(s):  
Environmental Factors ◽  
Suspended Sediment ◽  
Individual Component ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Lowland Rivers ◽  
Spatial And Temporal Scales ◽  
Suspension Concentration ◽  
Organic Components ◽  
The Impact

Abstract Concentrations of suspended sediment transported by rivers are influenced by interactions between multiple drivers that act on a range of spatial and temporal scales. Such levels vary over the year, as well as across multi-year periods. Most conventional approaches to determining suspended load are based upon analyses of total suspended sediment concentration (SSC), i.e., the sum of mineral and organic matter. This approach makes it difficult, if not impossible, to determine the impact of multiple environmental factors on changes in suspension concentration precisely. The present paper focuses on the mineral and organic components of suspended sediment with the aim of determining how our knowledge of the share of each individual component can improve interpretations of SSC fluctuations during a hydro-logical year. The analysis conducted (personal and other researchers’ results) has shown that mineral and organic suspensions demonstrate mutually incompatible opposite trends under influence of environmental factors. This analysis of organic components identifies clear seasonal trends, which indicates that organic suspensions of autogenous origin have a strong influence on the dynamics of changes in suspension concentration; such analyses are rarely included in assessments of SSC dynamics.

scholarly journals Desilting Basin Efficiency Estimation for Run-of-River Small Hydropower Plants

2019 ◽  
Vol 8 (4) ◽  
pp. 6389-6394
Keyword(s):  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Probabilistic Approach ◽  
Sediment Concentration ◽  
Operational Reliability ◽  
Maintenance Cost ◽  
Mathematical Function ◽  
Small Hydropower ◽  
The Impact ◽  
Run Of River

Suspended sediment concentration and discharge are important factors affecting the operational reliability of run-of-river small hydro power (SHP) plants. Elimination of sediment transported with the flow across the turbines of run-of-river plants is therefore a critical issue for the sustainability of the SHP industry. Comprise of a small diversion weir throughout a stream, the SHP plants does not have space to pile sediments but should be able to divert the incoming bed loads to the river downstream. Sediments in the water entering through the turbines with extreme velocity erode the contact surfaces of turbine mechanisms which results in reduced hydraulic efficiency and increased maintenance cost. Subsequently, desilting basins have become an essential part of the water conductor system of run-of-river SHP to reduce the impact of damage due to suspended sediment. Desilting basins are devised as settling basins to settle sediments larger than a targeted size. They are constructed just after power intake and discharge is despatched through them before pass into the head race tunnel. This study is aimed to estimate the sediment removal efficiency of SHP desilting basins based on data recorded at the intake of a run-of-river SHP. Considering the hydrological variability, probabilistic approach was used to obtain mathematical function for the probability density of suspended sediment concentration (SSC) based on the recorded data.

scholarly journals Impacts of dams on freshwater turtles: a global review to identify conservation solutions

2021 ◽  
Author(s):  
Andrea Barcenas-Garcia ◽  
Fernanda Michalski ◽  
William H. Morgan ◽  
Rebecca K. Smith ◽  
William J. Sutherland ◽  
...  
Keyword(s):  
Freshwater Ecosystems ◽  
Freshwater Turtle ◽  
Tropical Species ◽  
Life History Stage ◽  
Freshwater Turtles ◽  
Tropical Regions ◽  
Turtle Species ◽  
Threat Status ◽  
Dam Impacts ◽  
The Impact

Dams create many impacts on freshwater ecosystems and biodiversity. Freshwater turtles are at direct and indirect risk due to changes caused by damming including the loss of terrestrial and aquatic nesting and feeding habitats, changes to resource availability and reduced dispersal. We reviewed the global scientific literature that evaluated the impact of dams on freshwater turtles, and carried out additional searches of literature published in seventeen languages for studies evaluating actions to mitigate the impact of dams. The search produced 43 published articles documenting dam impacts on 29 freshwater turtle species from seven families (Chelidae, Chelydridae, Emydidae, Geoemydidae, Kinosternidae, Podocnemididae and Trionychidae) in 13 countries. More than a third of studies (41.9%, n = 18) focused on nine North American species of the Emydidae. Few studies were found from Europe and Asia and none from Africa. The number of studies, life-history stage studied and threat status differed significantly between temperate and tropical latitudes. Most studies were from temperate latitudes, where studies focused more on adults and less threatened species compared with tropical latitudes. Studies evaluated dam impacts as barriers and changes to water flow and quality, but no studies were found that assessed turtles and changes to land cover or mercury caused by dams. More than half of the studies (59%, n = 24) suggested actions to help mitigate dam impacts. Yet, only four studies on three temperate and one tropical species documented the effect of interventions (dam removal, flow management, artificial pond maintenance and community-based action). These findings demonstrate a lack of documented evidence evaluating dam impacts on freshwater turtles particularly in tropical regions. This lack of evidence reinforces the importance of strengthening and maintaining robust long-term studies of freshwater turtles needed to develop effective conservation actions for this group of vertebrates.

scholarly journals Unraveling the Essential Effects of Flocculation on Large-Scale Sediment Transport Patterns in a Tide-Dominated Estuary

2020 ◽  
Vol 50 (7) ◽  
pp. 1957-1981 ◽  
Author(s):  
Dante M. L. Horemans ◽  
Yoeri M. Dijkstra ◽  
Henk M. Schuttelaars ◽  
Patrick Meire ◽  
Tom J. S. Cox
Keyword(s):  
Sediment Transport ◽  
Suspended Sediment ◽  
Large Scale ◽  
Settling Velocity ◽  
Sediment Concentration ◽  
Order Effect ◽  
Temporal Variations ◽  
Small Scale ◽  
Estuarine Turbidity Maxima ◽  
The Impact

AbstractSediment transport in estuaries and the formation of estuarine turbidity maxima (ETM) highly depend on the ability of suspended particulate matter (SPM) to flocculate into larger aggregates. While most literature focuses on the small-scale impact of biological flocculants on the formation of larger aggregates, the influence of the flocculation process on large-scale estuarine SPM profiles is still largely unknown. In this paper, we study the impact of flocculation of SPM on the formation of ETM. For this, a semianalytical width-integrated model called iFlow is utilized and extended by a flocculation model. Starting from a complex one-class flocculation model, we show that flocculation may be described as a linear relation between settling velocity and suspended sediment concentration to capture its leading-order effect on the ETM formation. The model is applied to a winter case in the Scheldt estuary (Belgium, Netherlands) and calibrated to a unique, long-term, two-dimensional set of turbidity (cf. SPM) observations. First, model results with and without the effect of flocculation are compared, showing that the spatial and temporal variations of the settling velocity due to flocculation are essential to reproduce the observed magnitude of the suspended sediment concentrations and its dependence on river discharge. Second, flocculation results in tidally averaged land-inward sediment transport. Third, we conduct a sensitivity analysis of the freshwater discharge and floc breakup parameter, which shows that flocculation can cause additional estuarine turbidity maxima and can prevent flushing of the ETM for high freshwater inflow.

The effect of suspended sediment on fertilization success in sockeye (Oncorhynchus nerka) and coho (Oncorhynchus kisutch) salmon

2006 ◽  
Vol 63 (11) ◽  
pp. 2487-2494 ◽  
Author(s):  
Ryan V Galbraith ◽  
Erland A MacIsaac ◽  
J Stevenson Macdonald ◽  
Anthony P Farrell
Keyword(s):  
Suspended Sediment ◽  
Pacific Salmon ◽  
Oncorhynchus Nerka ◽  
Oncorhynchus Kisutch ◽  
Sediment Concentration ◽  
Fertilization Success ◽  
Suspended Sediment Concentrations ◽  
Controlled Flow ◽  
The Impact ◽  
The Relationship

Suspended sediment is a naturally occurring part of aquatic ecosystems, and unnatural elevation of suspended sediment in streams above background concentrations is known to adversely affect Pacific salmon (Oncorhynchus spp.) at different life stages. Conspicuously lacking in the literature is knowledge of the effect of suspended sediment on egg fertilization success during spawning. Sockeye (Oncorhynchus nerka) and coho (Oncorhynchus kisutch) salmon gametes were used to investigate the impact of different concentrations of suspended sediment particles on the ability of sperm to successfully fertilize eggs. The fertilization process was simulated using a controlled-flow water flume with concentrations of suspended particles ranging from 800 to 47 000 mg·L–1. Egg fertilization success was assessed at eyed stage after incubating eggs in the streambed in the field or in artificial laboratory egg incubation (Heath) trays. Regression model analysis showed that suspended sediment concentrations reduced the percent of fertilized eggs and that reduction in successful fertilization below 80% could occur when suspended sediment levels are in excess of 9000 mg·L–1. The relationship derived herein serves as a preliminary guideline for determining the effect size of suspended sediment concentration on egg fertilization success during spawning.

scholarly journals Trend of suspended sediment load in the Velika Morava River in the period 1967-2007

2014 ◽  
Vol 94 (4) ◽  
pp. 35-48
Author(s):  
Sanja Mustafic ◽  
Predrag Manojlovic ◽  
Milena Nikolic ◽  
Tanja Dobrosavljevic
Keyword(s):  
Suspended Sediment ◽  
Sediment Load ◽  
Statistical Significance ◽  
Kendall Test ◽  
Sediment Concentration ◽  
Average Decrease ◽  
Standardized Regression Coefficients ◽  
Mann Kendall Test ◽  
Morava River ◽  
The Impact

The paper is concerned with identifying changes in the time series of discharge (Q), suspended sediment concentration (SSC) and sediment load (Qs) of the Velika Morva River. The catchment area on farthest hydrological profile Ljubicevski most on Velika Morava River is approximately 35,496 km2. In this profile were carried out daily measurements of flow and concetration of silt in the period from 1967 to 2007. Average perennial transport of suspended sediment is 2.57?106 t (72.4 t/km2/yr) and ranged from 0.17?106 t (4.8 t/km2/yr) to 10.02?106 t (282.2 t/km2/yr). Trends determined for Q, SSC and Qs are statistically obtained using the non-parametric Mann-Kendall test. Results of Mann-Kendall test show that Q has a slight declining trend of annual values which do not show statistical significance. Decline in trendline SSC and Qs is a significant at the level of 0.01. Calculating the standardized regression coefficients, it was found that the relative impact of SSC on sediment load is 3.1 time higher than the impact of discharge. From 1967 to 2007 the average decrease in sediment load at the mouth of the Velika Morava into the Danube was 3.1 t/km2/yr.

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