Journal articles: 'Turbid freshwaters'

1

Grobbelaar, Johan U. "The contribution of phytoplankton in turbid freshwaters to their trophic status." SIL Proceedings, 1922-2010 23, no. 2 (August 1988): 1020–21. http://dx.doi.org/10.1080/03680770.1987.11899761.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Grobbelaar, Johan U. "The contribution of phytoplankton productivity in turbid freshwaters to their trophic status." Hydrobiologia 173, no. 2 (March 1989): 127–33. http://dx.doi.org/10.1007/bf00015522.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Barouillet, Cécilia, Brian F. Cumming, Kathleen R. Laird, Christopher J. Perrin, and Daniel T. Selbie. "Influence of glacial flour on the primary and secondary production of sockeye salmon nursery lakes: a comparative modern and paleolimnological study." Canadian Journal of Fisheries and Aquatic Sciences 76, no. 12 (December 2019): 2303–14. http://dx.doi.org/10.1139/cjfas-2018-0372.

Full text

Abstract:

The increasing rate of glacier retreat and turbid glacial runoff can have a strong influence on freshwater ecosystems. Seton and Anderson lakes (British Columbia, Canada) are sockeye salmon (Oncorhynchus nerka) nursery systems. Since the 1940s, the Bridge River Diversion (BRD) introduced glacially turbid water into Seton Lake. To assess the impact of the BRD on the production of Seton Lake, we combined data from limnological surveys with the analysis of subfossil cladocerans and diatoms from sediment cores, using Anderson Lake as a reference. The modern data indicate that the euphotic zone is 14 m shallower and the cladoceran density and biomass are significantly lower in Seton Lake in comparison with Anderson Lake. The paleo-data indicate that following the BRD, the sedimentary fluxes of cladoceran and diatom declined 2- to 10-fold in Seton Lake and remained low thereafter. Together, our data support declines in primary and secondary producers following the BRD, likely due to changes in light penetration and (or) other indirect influence, and provides insights into the impact of turbid meltwater on the biological production of downstream lakes.

APA, Harvard, Vancouver, ISO, and other styles

4

Abrahams, Mark V. "Risk of Predation and Its Influence on the Relative Competitive Abilities of Two Species of Freshwater Fishes." Canadian Journal of Fisheries and Aquatic Sciences 51, no. 7 (July 1, 1994): 1629–33. http://dx.doi.org/10.1139/f94-163.

Full text

Abstract:

Experiments were conducted with fathead minnow (Pimephales promelas) and brook stickleback (Culaea inconstans) to determine whether their relative feeding rates were affected by risk of predation. Six groups of both species were observed foraging for food provided by an automated feeder while two parameters were manipulated: the presence or absence of a predator, yellow perch (Perca flavescens), and clear or turbid water. It was hypothesized that the armour and spines of brook stickleback would be of greatest benefit during a direct encounter with a predator. I attempted to simulate this condition with turbid water and predator present. Feeding rates of the two species were significantly different, with fathead minnow feeding at a greater rate than brook stickleback in the absence of a predator. In the presence of a predator the feeding rate of fathead minnow declined significantly whereas that of brook stickleback was unaffected. This resulted in similar feeding rates for the two species in the presence of a predator. Results demonstrate that risk of predation can alter the relative competitive abilities of two species in situations where one species possesses a morphological adaptation against predation. In the absence of predators, these traits may be detrimental in interspecific competition for food.

APA, Harvard, Vancouver, ISO, and other styles

5

Lobo, Felipe L., Maycira Costa, Stephen Phillips, Erika Young, and Cory McGregor. "Light backscattering in turbid freshwater: a laboratory investigation." Journal of Applied Remote Sensing 8, no. 1 (June 25, 2014): 083611. http://dx.doi.org/10.1117/1.jrs.8.083611.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

El-Alem, Anas, Karem Chokmani, Aarthi Venkatesan, Lhissou Rachid, Hachem Agili, and Jean-Pierre Dedieu. "How Accurate Is an Unmanned Aerial Vehicle Data-Based Model Applied on Satellite Imagery for Chlorophyll-a Estimation in Freshwater Bodies?" Remote Sensing 13, no. 6 (March 17, 2021): 1134. http://dx.doi.org/10.3390/rs13061134.

Full text

Abstract:

Optical sensors are increasingly sought to estimate the amount of chlorophyll a (chl_a) in freshwater bodies. Most, whether empirical or semi-empirical, are data-oriented. Two main limitations are often encountered in the development of such models. The availability of data needed for model calibration, validation, and testing and the locality of the model developed—the majority need a re-parameterization from lake to lake. An Unmanned aerial vehicle (UAV) data-based model for chl_a estimation is developed in this work and tested on Sentinel-2 imagery without any re-parametrization. The Ensemble-based system (EBS) algorithm was used to train the model. The leave-one-out cross validation technique was applied to evaluate the EBS, at a local scale, where results were satisfactory (R2 = Nash = 0.94 and RMSE = 5.6 µg chl_a L−1). A blind database (collected over 89 lakes) was used to challenge the EBS’ Sentine-2-derived chl_a estimates at a regional scale. Results were relatively less good, yet satisfactory (R2 = 0.85, RMSE= 2.4 µg chl_a L−1, and Nash = 0.79). However, the EBS has shown some failure to correctly retrieve chl_a concentration in highly turbid waterbodies. This particularity nonetheless does not affect EBS performance, since turbid waters can easily be pre-recognized and masked before the chl_a modeling.

APA, Harvard, Vancouver, ISO, and other styles

7

Ohashi, Yoshihiko, Shigeru Aoki, Yoshimasa Matsumura, Shin Sugiyama, Naoya Kanna, and Daiki Sakakibara. "Vertical distribution of water mass properties under the influence of subglacial discharge in Bowdoin Fjord, northwestern Greenland." Ocean Science 16, no. 3 (May 4, 2020): 545–64. http://dx.doi.org/10.5194/os-16-545-2020.

Full text

Abstract:

Abstract. Subglacial discharge has significant impacts on water circulation, material transport, and biological productivity in proglacial fjords of Greenland. To help clarify the fjord water properties and the effect of subglacial discharge, we investigated the properties of vertical water mass profiles of Bowdoin Fjord in northwestern Greenland based on summer hydrographic observations, including turbidity, in 2014 and 2016. We estimated the fraction of subglacial discharge from the observational data and interpreted the observed differences in subglacial plume behavior between two summer seasons with the numerical model results. At a depth of 15–40 m, where the most turbid water was observed, the maximum subglacial discharge fractions near the ice front were estimated to be ∼6 % in 2014 and ∼4 % in 2016. The higher discharge fraction in 2014 was likely due to stronger stratification, as suggested by the numerical experiments performed with different initial stratifications. Turbidity near the surface was higher in 2016 than in 2014, suggesting a stronger influence of turbid subglacial discharge. The higher turbidity in 2016 could primarily be attributed to a greater amount of subglacial discharge, as inferred from the numerical experiments forced by different amounts of discharge. This study suggests that both fjord stratification and the amount of discharge are important factors in controlling the vertical distribution of freshwater outflow.

APA, Harvard, Vancouver, ISO, and other styles

8

Kwon, S. B., H. W. Ahn, C. J. Ahn, and C. K. Wang. "A case study of dissolved air flotation for seasonal high turbidity water in Korea." Water Science and Technology 50, no. 12 (December 1, 2004): 245–53. http://dx.doi.org/10.2166/wst.2004.0720.

Full text

Abstract:

A DAF (Dissolved-Air-Flotation) process has been designed considering raw water quality characteristics in Korea. Although direct filtration is usually operated, DAF is operated when freshwater algae blooms occur or raw water turbidity becomes high. Pre-sedimentation is operated in case when the raw water turbidity is very high due to rainstorms. A main feature of this plant is that the operation mode can be changed (controlled) based on the characteristics of the raw water to optimize the effluent quality and the operation costs. Treatment capacity (surface loading rate) and efficiency of DAF was found to be better than the conventional sedimentation process. Moreover, low-density particles (algae and alum flocs) are easily separated while the removal of them by sedimentation is more difficult. One of the main concerns for DAF operation is a high raw water turbidity. DAF is not adequate for raw water, which is more turbid than 100 NTU. In order to avoid this problem, pre-sedimentation basins are installed in the DAF plant to decrease the turbidity of the DAF inflow. For simulation of the actual operation, bench and full-scale tests were performed for highly turbid water conditions. Consequently, it is suggested that pre-sedimentation with optimum coagulation prior to DAF is the appropriate treatment scheme.

APA, Harvard, Vancouver, ISO, and other styles

9

Nishizawa, Bungo, Naoya Kanna, Yoshiyuki Abe, Yoshihiko Ohashi, Daiki Sakakibara, Izumi Asaji, Shin Sugiyama, Atsushi Yamaguchi, and Yutaka Watanuki. "Contrasting assemblages of seabirds in the subglacial meltwater plume and oceanic water of Bowdoin Fjord, northwestern Greenland." ICES Journal of Marine Science 77, no. 2 (December 14, 2019): 711–20. http://dx.doi.org/10.1093/icesjms/fsz213.

Full text

Abstract:

Abstract In Greenland, tidewater glaciers discharge turbid subglacial freshwater into fjords, forming plumes near the calving fronts, and these areas serve as an important foraging habitat for seabirds. To investigate the effect of subglacial discharge on the foraging assemblages of surface feeders and divers in a glacial fjord, we conducted boat-based seabird surveys, near-surface zooplankton samplings, and hydrographic measurements at Bowdoin Fjord, northwestern Greenland in July. Foraging surface feeders (black-legged kittiwake Rissa tridactyla, glaucous gull Larus hyperboreus, and northern fulmar Fulmarus glacialis) aggregated within a plume-affected area in front of Bowdoin Glacier. This area was characterized by highly turbid subglacial meltwater and abundant large-sized zooplankton including Calanus hyperboreus, chaetognaths, and ctenophores near the surface. Surface feeders fed on these aggregated prey presumably transported to the surface by strong upwelling of subglacial meltwater. In contrast, divers (little auk Alle alle, thick-billed murre Uria lomvia, and black guillemot Cepphus grylle) foraged outside the fjord, where turbidity was low and jellyfish and Calanus copepods dominated under the influence of Atlantic water. Our study indicates spatial segregation between surface feeders and divers in a glacial fjord; surface feeders are not hindered by turbidity if taking prey at the surface, whereas divers need clear water.

APA, Harvard, Vancouver, ISO, and other styles

10

Cantonati, Poikane, Pringle, Stevens, Turak, Heino, Richardson, et al. "Characteristics, Main Impacts, and Stewardship of Natural and Artificial Freshwater Environments: Consequences for Biodiversity Conservation." Water 12, no. 1 (January 16, 2020): 260. http://dx.doi.org/10.3390/w12010260.

Full text

Abstract:

In this overview (introductory article to a special issue including 14 papers), we consider all main types of natural and artificial inland freshwater habitas (fwh). For each type, we identify the main biodiversity patterns and ecological features, human impacts on the system and environmental issues, and discuss ways to use this information to improve stewardship. Examples of selected key biodiversity/ecological features (habitat type): narrow endemics, sensitive (groundwater and GDEs); crenobionts, LIHRes (springs); unidirectional flow, nutrient spiraling (streams); naturally turbid, floodplains, large-bodied species (large rivers); depth-variation in benthic communities (lakes); endemism and diversity (ancient lakes); threatened, sensitive species (oxbow lakes, SWE); diverse, reduced littoral (reservoirs); cold-adapted species (Boreal and Arctic fwh); endemism, depauperate (Antarctic fwh); flood pulse, intermittent wetlands, biggest river basins (tropical fwh); variable hydrologic regime—periods of drying, flash floods (arid-climate fwh). Selected impacts: eutrophication and other pollution, hydrologic modifications, overexploitation, habitat destruction, invasive species, salinization. Climate change is a threat multiplier, and it is important to quantify resistance, resilience, and recovery to assess the strategic role of the different types of freshwater ecosystems and their value for biodiversity conservation. Effective conservation solutions are dependent on an understanding of connectivity between different freshwater ecosystems (including related terrestrial, coastal and marine systems).

APA, Harvard, Vancouver, ISO, and other styles

11

Schaffer, Jason R., Mark Hamann, Richard Rowe, and Damien W. Burrows. "Muddy waters: the influence of high suspended-sediment concentration on the diving behaviour of a bimodally respiring freshwater turtle from north-eastern Australia." Marine and Freshwater Research 67, no. 4 (2016): 505. http://dx.doi.org/10.1071/mf14117.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

12

Bowling, LC. "Optical properties, Nutrients and Phytoplankton of freshwater Coastal Dune Lakes in South-east Queensland." Marine and Freshwater Research 39, no. 6 (1988): 805. http://dx.doi.org/10.1071/mf9880805.

Full text

Abstract:

Gilvin was the main attenuator of photosynthetically available radiation (PAR) in 26 freshwater coastal dune lakes, despite most being only slightly humic (range 0.000-27.866 m-1, median = 1.088 m-1). Most were also non-turbid [range 0.27-3.00 nephelometric turbidity units (NTU), median = 0.77 NTU] and had low concentrations of chlorophyll a (range 0.212-15.869 �g I-1, median = 3.285 �g I-1). Accordingly there was only slight to moderate attenuation of PAR in most lakes, the majority having mean downwelling vertical attenuation coefficients of less than 1.0 m-1. However, Secchi depths indicate that the lake waters were more transparent during this study than previously reported in the literature. The lakes were typically oligotrophic, acidic, and of low conductivity. Desmids and Peridinium spp. dominated the phytoplankton, although Dynobryon cylindricum Imhof. and various Chlorococcales were also common.

APA, Harvard, Vancouver, ISO, and other styles

13

Bashawri, Yasir M., Peter Robins, David M. Cooper, James E. McDonald, Davey L. Jones, and A. Prysor Williams. "Impact of Sediment Concentration on the Survival of Wastewater-Derived blaCTX-M-15-Producing E. coli, and the Implications for Dispersal into Estuarine Waters." International Journal of Environmental Research and Public Health 17, no. 20 (October 19, 2020): 7608. http://dx.doi.org/10.3390/ijerph17207608.

Full text

Abstract:

The environmental cycling of antibiotic-resistant blaCTX-M-15-producing E. coli following release from wastewater treatment plants is a major public health concern. This study aimed to (i) assess the impact of sediment concentrations on the rate of their inactivation following release from human wastewater into freshwater, and (ii) simulate their subsequent dispersal to the nearby coastline during a “worst-case” event where heavy rainfall coincided with high spring tide in the Conwy Estuary, North Wales. Freshwater microcosms of low, medium and high turbidity were inoculated with blaCTX-M-15-producing E. coli, then exposed to ultraviolet (UV) radiation. Typical regional wintertime exposure to UV was found to be insufficient to eradicate E. coli, and in highly turbid water, many bacteria survived simulated typical regional summertime UV exposure. Modelling results revealed that blaCTX-M-15-producing E. coli concentrations reduced downstream from the discharge source, with ~30% of the source concentration capable of dispersing through the estuary to the coast, taking ~36 h. Offshore, the concentration simulated at key shellfisheries and bathing water sites ranged from 1.4% to 10% of the upstream input, depending on the distance offshore and tidal regime, persisting in the water column for over a week. Our work indicates that the survival of such organisms post-release into freshwater is extended under typical wintertime conditions, which could ultimately have implications for human health.

APA, Harvard, Vancouver, ISO, and other styles

14

Coates, D. "Aspects of the Biology of the Perchlet Ambassis interrupta Bleeker (Pisces: Ambassidae) in the Sepik River, Papua New Guinea." Marine and Freshwater Research 41, no. 2 (1990): 267. http://dx.doi.org/10.1071/mf9900267.

Full text

Abstract:

Ambassis interrupta enters the lower Sepik River and is found in or near turbid river channels. The species is considered to be a predominantly marine and/or estuarine spawner. A. interrupta feeds mainly on small aquatic insect larvae but also on insects from terrestrial sources and on small crustaceans. Low variability in the data for condition, fat deposition, reproduction and feeding is interpreted by the species' lack of affinity for the floodplain and the presumed transient nature of the population. Fecundity (F) is expressed by the formula F= - 12.3 + I5.3, where I is standard length (mm), and varied between 29 000 and 310 000 eggs per fish (70-105 mm standard length). Eggs are small (0.22 mm mean diameter) in comparison with known egg sizes for freshwater-spawning ambassids.

APA, Harvard, Vancouver, ISO, and other styles

15

Ratnasari, Devi, Rodhiyah, and Arif Pramudwiatmoko. "IoT Prototype Development of Automatic Fish Feeder and Water Replacement." International Journal of Engineering Technology and Natural Sciences 2, no. 2 (April 5, 2021): 51–55. http://dx.doi.org/10.46923/ijets.v2i2.71.

Full text

Abstract:

In raising the freshwater fish in the aquarium, we need to pay attention on the fish’s health by noticing the feeding time and the aquarium cleanness. The busy fish owners sometimes do not have time to clean the aquarium and replace the water. The food is even not given regularly. The system which can be developed to help the fish owners in handling the problems in raising the fish is the scheduled automatic feeding monitoring system and automatic water changer when the water has turned turbid. The system is developed by using the NodeMCU ESP8266 as the controlling center and in the same time it helps the system to connect to internet. The system is equipped with the website page to help the fish owner in monitoring the aquarium condition from the distance.

APA, Harvard, Vancouver, ISO, and other styles

16

Kaya, Sinasi, Dursun Z. Seker, Sedat Kabdasli, Nebiye Musaoglu, Akira Yuasa, and Madhusudan B. Shrestha. "Monitoring turbid freshwater plume characteristics by means of remotely sensed data." Hydrological Processes 20, no. 11 (2006): 2429–40. http://dx.doi.org/10.1002/hyp.6067.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Hofmann, A. F., F. J. R. Meysman, K. Soetaert, and J. J. Middelburg. "Factors governing the pH in a heterotrophic, turbid, tidal estuary." Biogeosciences Discussions 6, no. 1 (January 7, 2009): 197–240. http://dx.doi.org/10.5194/bgd-6-197-2009.

Full text

Abstract:

Abstract. A method to quantify the influence of kinetically modelled biogeochemical processes on the pH of an ecosystem with time variable acid-base dissociation constants is presented and applied to the heterotrophic, turbid Scheldt estuary (SW Netherlands, N Belgium). Nitrification is identified as the main process governing the pH profile of this estuary, while CO2 degassing and advective-dispersive transport "buffer" the effect of nitrification. CO2 degassing accounts for the largest proton turnover per year in the whole estuary. There is a clear inverse correlation between oxygen turnover and proton turnover. The main driver of long-term changes in the mean estuarine pH from 2001 to 2004 is a changing freshwater flow which influences the pH "directly" via [∑CO2] and [TA] and to a significant amount also "indirectly" via [∑NH4+] and the nitrification rates in the estuary.

APA, Harvard, Vancouver, ISO, and other styles

18

Clarke, Garry K. C., Andrew B. G. Bush, and John W. M. Bush. "Freshwater Discharge, Sediment Transport, and Modeled Climate Impacts of the Final Drainage of Glacial Lake Agassiz." Journal of Climate 22, no. 8 (April 15, 2009): 2161–80. http://dx.doi.org/10.1175/2008jcli2439.1.

Full text

Abstract:

Abstract A cold event at around 8200 calendar years BP and the release, at around that time, of a huge freshwater outburst from ice-dammed glacial Lake Agassiz have lent support to the idea that the flood triggered the cold event. Some suggest that the freshwater addition caused a weakening of the North Atlantic meridional overturning circulation (MOC) thereby reducing the ocean transport of heat to high northern latitudes. Although several modeling efforts lend strength to this claim, the paleoceanographic record is equivocal. The authors’ aim is to use a coupled ocean–atmosphere model to examine the possibility that the two events are causally linked but that MOC reduction was not the main agent of change. It is found that the outburst flood and associated redirection of postflood meltwater drainage to the Labrador Sea, via Hudson Strait, can freshen the North Atlantic, leading to reduced salinity and sea surface temperature, and thus to increased sea ice production at high latitudes. The results point to the possibility that the preflood outflow to the St. Lawrence was extremely turbid and sufficiently dense to become hyperpycnal, whereas the postflood outflow through Hudson Strait had a lower load of suspended sediment and was buoyant.

APA, Harvard, Vancouver, ISO, and other styles

19

Bertrand, Normand, and Warwick F. Vincent. "Structure and Dynamics of Photosynthetic Picoplankton across the Saltwater Transition Zone of the St. Lawrence River." Canadian Journal of Fisheries and Aquatic Sciences 51, no. 1 (January 1, 1994): 161–71. http://dx.doi.org/10.1139/f94-018.

Full text

Abstract:

Changes in the biomass, community structure, and activity of photosynthetic picoplankton (PP) were measured across the turbid, freshwater–saltwater transition zone (TZ) of the St. Lawrence River. The <2 μm fraction of total Chl a dropped from 20–30% in mid-May to 15% in late June. Photosynthesis by the <2.0 μm fraction in May surface waters contributed 6–38% of the total primary production. Picoplankton dropped from 8.4 × 106 (freshwater zone, FZ) to 3.7 × 106 cells∙L−1 (TZ) in mid-May and from 17 × 106 (FZ) to 5.8 × 106 cells∙L−1 (TZ) in late June. Results implied that the picoplankton were subject to increased losses (e.g., by protozoan grazing) in the TZ. Phycoerythrin-rich cyanobacteria (PEC) dominated the PP counts in mid-May, with phycocyanin-rich forms (PCC) contributing 4–13% of the cell concentrations. Six weeks later the PP community had shifted completely to PCC dominance (60–69% of total counts). In late summer, PP contributed 6–56% of the planktonic Chl a in the St. Lawrence River system. There were large variations in the PEC/PCC ratio and the proportion of eukaryotic PP along certain reaches of the river. These observations underscore the spatially and temporally dynamic character of PP communities in the river–estuary environment.

APA, Harvard, Vancouver, ISO, and other styles

20

Young, Matthew, Emily Howe, Teejay O’Rear, Kathleen Berridge, and Peter Moyle. "Food Web Fuel Differs Across Habitats and Seasons of a Tidal Freshwater Estuary." Estuaries and Coasts 44, no. 1 (July 11, 2020): 286–301. http://dx.doi.org/10.1007/s12237-020-00762-9.

Full text

Abstract:

AbstractEstuarine food webs are fueled by multiple different primary producers. However, identifying the relative importance of each producer to consumers is difficult, particularly for fishes that utilize multiple food sources due to both their mobility and their generally high trophic levels. Previous studies have documented broad spatial differences in the importance of primary producers to fishes within the Upper San Francisco Estuary, California, including separation between pelagic and littoral food webs. In this study, we evaluated the importance of primary producers to adult fishes in three closely spaced subregions that represented disparate habitat types (a tidal wetland channel, a turbid backwater channel, and a deep open-water channel), each a potential outcome of local restoration projects. Using stable isotope analysis coupled with a Bayesian mixing model, we identified significant differences in primary-producer contribution to fishes and invertebrates across habitats and seasons, especially in the relative contribution of submersed aquatic vegetation and phytoplankton. Most fishes utilized multiple primary producers and showed little segregation between pelagic and littoral food webs among habitats. Availability of primary producers differs seasonally and across multiple spatial scales, helping to buffer environmental variability and thus enhancing food web resilience. Ecosystem restoration may improve with emphasis on restoring a wide variety of primary producers to support consumers.

APA, Harvard, Vancouver, ISO, and other styles

21

Cole, Jonathan J., Nina F. Caraco, and Benjamin L. Peierls. "Can phytoplankton maintaina positive carbon balance in a turbid, freshwater, tidal estuary?" Limnology and Oceanography 37, no. 8 (December 1992): 1608–17. http://dx.doi.org/10.4319/lo.1992.37.8.1608.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Pizarro, H., M. S. Vera, A. Vinocur, G. Pérez, M. Ferraro, R. J. Menéndez Helman, and M. dos Santos Afonso. "Glyphosate input modifies microbial community structure in clear and turbid freshwater systems." Environmental Science and Pollution Research 23, no. 6 (November 10, 2015): 5143–53. http://dx.doi.org/10.1007/s11356-015-5748-0.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Xu, Dandan, Dong Zhang, Dan Shi, and Zhaoqing Luan. "Automatic Extraction of Open Water Using Imagery of Landsat Series." Water 12, no. 7 (July 6, 2020): 1928. http://dx.doi.org/10.3390/w12071928.

Full text

Abstract:

Open surface freshwater is an important resource for terrestrial ecosystems. However, climate change, seasonal precipitation cycling, and anthropogenic activities add high variability to its availability. Thus, timely and accurate mapping of open surface water is necessary. In this study, a methodology based on the concept of spatial autocorrelation was developed for automatic water extraction from Landsat series images using Taihu Lake in south-eastern China as an example. The results show that this method has great potential to extract continuous open surface water automatically, even when the water surface is covered by floating vegetation or algal blooms. The results also indicate that the second shortwave-infrared band (SWIR2) band performs best for water extraction when water is turbid or covered by surficial vegetation. Near-infrared band (NIR), first shortwave-infrared band (SWIR1), and SWIR2 have consistent extraction success when the water surface is not covered by vegetation. Low filter image processing greatly overestimated extracted water bodies, and cloud and image salt and pepper issues have a large impact on water extraction using the methods developed in this study.

APA, Harvard, Vancouver, ISO, and other styles

24

Lyon, Jarod P., Robin Hale, Adrian Kitchingman, Justin O'Connor, Joanne Sharley, and Zeb Tonkin. "Effects of tag type, morphological location and tagger experience on tag retention rates in freshwater fishes." Marine and Freshwater Research 70, no. 6 (2019): 891. http://dx.doi.org/10.1071/mf18368.

Full text

Abstract:

Mark–recapture of fish is often used to inform fisheries or conservation management. Given that variability in tagging efficiencies can affect estimates of population size, it is important that rates of tag rejection are quantified. We double tagged over 45000 large-bodied, long-lived fish in a turbid lowland river in south-eastern Australia. During yearly recapture fish surveys, data on tag rejection were collected. We found that the probability of tag rejection varied as a function of fish species, tag type and tagger experience. Floy tags were more likely to be rejected as dart tags in large-bodied golden perch Macquaria ambigua (6 and 3% respectively), silver perch (18 and 4% respectively) and trout cod (19 and 7% respectively), whereas rates of rejection in the large-bodied Murray cod Maccullochella peelii were similar for both tag types (12 and 10% respectively). More experienced taggers had lower rates of rejection, which varied between 1 and 48% for individual taggers. We trialled three morphological locations for passive integrated transponder (PIT) tagging of fish, with rejection rates lowest for tags implanted in the stomach cavity and highest for those implanted in the pectoral musculature. This study presents the first tag rejection rates for dart, floy and PIT tags for lowland Australian river fish, information that can help guide future monitoring programs.

APA, Harvard, Vancouver, ISO, and other styles

25

Masson, Matthieu, Gérard Blanc, Jörg Schäfer, Edith Parlanti, and Philippe Le Coustumer. "Copper addition by organic matter degradation in the freshwater reaches of a turbid estuary." Science of The Total Environment 409, no. 8 (March 2011): 1539–49. http://dx.doi.org/10.1016/j.scitotenv.2011.01.022.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Saldías, Gonzalo S., P. Ted Strub, and R. Kipp Shearman. "Spatio-temporal variability and ENSO modulation of turbid freshwater plumes along the Oregon coast." Estuarine, Coastal and Shelf Science 243 (September 2020): 106880. http://dx.doi.org/10.1016/j.ecss.2020.106880.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Rodrigues, Raphael Paiva, Bastiaan Adriaan Knoppers, Weber Friederichs Landim de Souza, and Elisamara Sabadini Santos. "Suspended matter and nutrient gradients of a small-scale river plume in Sepetiba Bay, SE-Brazil." Brazilian Archives of Biology and Technology 52, no. 2 (April 2009): 503–12. http://dx.doi.org/10.1590/s1516-89132009000200030.

Full text

Abstract:

Coastal river plumes represent one of the final stages of material transport across the land-sea interface. Most studies, however have focused on the behavior of medium to large sized river plumes of coastal-shelf waters, whereas small sized river plumes acting within estuaries have been neglected. This study addressed the behavior of suspended particulate matter (SPM), dissolved inorganic nutrients (DIN, DIP and DSi) and Chlorophyll a (Chl. a) of a small sized river plume derived from the closely lain São Francisco and Guandú river channels, set in the Sepetiba Bay estuary, SE-Brazil. Two surface water sampling campaigns were conducted, one in January 2003 (humid summer conditions) and the other in June 2003 (dry winter conditions). On both occasions, the plumes dispersed in a SE direction towards the inner portion of the bay. The "wet" event plume was more turbid, nutrient rich and dispersed beyond nearshore waters, whereas the "dry" event plume proliferated as a narrow, less turbid and more nutrient poor film alongshore. Both exhibited a marked degree of patchiness, induced by the differential input of materials from the river sources and resuspension processes from the shallow nearshore bottom. The São Francisco river channel was the main source of freshwater, SPM and nutrients, except for ammonia (NH4+-N) derived from domestic effluents of the Guandú river. The mesohaline portion of the estuarine mixing zone of the plumes behaved as a slight source for SPM, DSi and DIP, due to bottom resuspension processes. N:P molar ratios ranged between 80:1 and 20:1 along the estuarine gradient, being higher in the summer than in the winter event, indicating that DIP was the potential nutrient limiting primary production. Chl. a concentrations increased at the outer premises of the plume, suggesting that the short residence times and turbidity of the plume waters, hampered primary production nearshore, particularly during the summer occasion. The small sized plume lacked the spatial decoupling between the estuarine mixing and turbidity zones, generally observed in larger sized coastal-shelf plumes.

APA, Harvard, Vancouver, ISO, and other styles

28

Hofmann, A. F., J. J. Middelburg, K. Soetaert, and F. J. R. Meysman. "pH modelling in aquatic systems with time-variable acid-base dissociation constants applied to the turbid, tidal Scheldt estuary." Biogeosciences 6, no. 8 (August 7, 2009): 1539–61. http://dx.doi.org/10.5194/bg-6-1539-2009.

Full text

Abstract:

Abstract. A new pH modelling approach is presented that explicitly quantifies the influence of biogeochemical processes on proton cycling and pH in an aquatic ecosystem, and which accounts for time variable acid-base dissociation constants. As a case study, the method is applied to investigate proton cycling and long-term pH trends in the Scheldt estuary (SW Netherlands, N Belgium). This analysis identifies the dominant biogeochemical processes involved in proton cycling in this heterotrophic, turbid estuary. Furthermore, information on the factors controlling the longitudinal pH profile along the estuary as well as long-term pH changes are obtained. Proton production by nitrification is identified as the principal biological process governing the pH. Its acidifying effect is mainly counteracted by proton consumption due to CO2 degassing. Overall, CO2 degassing generates the largest proton turnover in the whole estuary on a yearly basis. The main driver of long-term changes in the mean estuarine pH over the period 2001 to 2004 is the decreasing freshwater flow, which influences the pH directly via a decreasing supply of dissolved inorganic carbon and alkalinity, and also indirectly, via decreasing ammonia loadings and lower nitrification rates.

APA, Harvard, Vancouver, ISO, and other styles

29

Vilizzi, Lorenzo, Leigh A. Thwaites, Benjamin B. Smith, Jason M. Nicol, and Chris P. Madden. "Ecological effects of common carp (Cyprinus carpio) in a semi-arid floodplain wetland." Marine and Freshwater Research 65, no. 9 (2014): 802. http://dx.doi.org/10.1071/mf13163.

Full text

Abstract:

Common carp, Cyprinus carpio, is a highly invasive fish species across freshwater systems of south-eastern Australia, and especially in semi-arid floodplain wetlands. However, multi-component, large-scale experimental studies on carp effects on such ecosystems are scarce. This is in spite of demands to prioritise management and control of carp for the rehabilitation of habitats across the Murray–Darling Basin. A 2-year, large-scale field experiment in a terminal wetland of the lower River Murray (South Australia) evaluated the effects of free-ranging carp on water transparency, aquatic macrophytes (biomass and cover), zooplankton density, benthic invertebrates (density, richness and diversity) as well as native fish. Within 1 year since artificial inundation, transparency sharply decreased and this was accompanied by a decrease in aquatic macrophyte biomass and cover, a fluctuation in zooplankton density, and a decrease in benthic invertebrate richness and diversity. Also, the decreases in transparency and benthic invertebrate richness were significantly related to carp biomass, which averaged 68.0 kg ha–1 and induced a shift from clear- to turbid-water state. Following a flood event, increased connectivity caused carp to further access the newly inundated areas.

APA, Harvard, Vancouver, ISO, and other styles

30

Hodgkins, Richard, Robert Bryant, Eleanor Darlington, and Mark Brandon. "Pre-melt-season sediment plume variability at Jökulsárlón, Iceland, a preliminary evaluation using in-situ spectroradiometry and satellite imagery." Annals of Glaciology 57, no. 73 (May 12, 2016): 39–46. http://dx.doi.org/10.1017/aog.2016.20.

Full text

Abstract:

ABSTRACTHigh-latitude atmospheric warming is impacting freshwater cycling, requiring techniques for monitoring the hydrology of sparsely-gauged regions. The submarine runoff of tidewater glaciers presents a particular challenge. We evaluate the utility of Moderate Resolution Imaging Spectroradiometer (MODIS) imagery for monitoring turbid meltwater plume variability in the glacier lagoon Jökulsárlón, Iceland, for a short interval before the onset of the main melt season. Total Suspended Solids concentrations (TSS) of surface waters are related to remotely-sensed reflectance via empirical calibration between in-situ-sampled TSS and reflectance in a MODIS band 1-equivalent wavelength window. This study differs from previous ones in its application to an overturning tidewater glacier plume, rather than one derived from river runoff. The linear calibration improves on previous studies by facilitating a wider range of plume metrics than areal extent, notably pixel-by-pixel TSS values. Increasing values of minimum plume TSS over the study interval credibly represent rising overall turbidity in the lagoon as melting accumulates. Plume extent responds principally to consistently-strong offshore winds. Further work is required to determine the temporal persistence of the calibration, but remote plume observation holds promise for monitoring hydrological outputs from ungauged or ungaugeable systems.

APA, Harvard, Vancouver, ISO, and other styles

31

Risberg, Jan, Per Sandgren, James T. Teller, and William M. Last. "Siliceous microfossils and mineral magnetic characteristics in a sediment core from Lake Manitoba, Canada: a remnant of glacial Lake Agassiz." Canadian Journal of Earth Sciences 36, no. 8 (August 21, 1999): 1299–314. http://dx.doi.org/10.1139/e99-022.

Full text

Abstract:

A 14.2 m long core was recovered from the southern Lake Manitoba basin. The sediment, consisting mainly of silty clay, was studied for siliceous microfossil content and mineral magnetics; 14 new accelerator mass spectrometry (AMS) radiocarbon dates provide chronological control of the paleoenvironmental history of the basin. The basal 5 m contains ice-rafted clasts and is largely barren of siliceous microfossils; these sediments were deposited when the lake was part of glacial Lake Agassiz. Sediments immediately overlying the barren part of the sequence contain AMS dates of 7700-7400 BP and reflect a dramatic change in conditions in the basin. Diatom abundances rise abruptly. Magnetic characteristics change substantially. The presence of freshwater taxa such as Stephanodiscus niagarae, together with brackish water diatoms, indicate that shallow, turbid, high-nutrient conditions with variable salinity occurred during the early part of the middle Holocene. Although climatic conditions throughout the northern Great Plains are known to have become drier and warmer during the mid-Holocene, there is a distinct change in diatom taxa in the Lake Manitoba sequence toward less saline conditions at this time. The presence of the riverine diatom Aulacoseira granulata in this interval supports previous conclusions that these freshwater conditions resulted from the northward diversion of the Assiniboine River into the basin. Following this, diatoms indicate an abrupt increase in salinity to >1500 mg·L-1 total dissolved solids between 4000 and 2600 BP, reflecting the diversion of the fresh waters of the Assiniboine River away from Lake Manitoba. Increasingly cooler and wetter conditions during the late Holocene, combined with differential isostatic rebound, caused a freshening of the lake during the late Holocene.

APA, Harvard, Vancouver, ISO, and other styles

32

Pal, Sheela, and Nankumar Kamat. "Fractal analysis of colony margins as an aid for screening freshwater yeast cultures for bioclarification of turbid polluted water resources." Journal of Applied and Natural Science 11, no. 2 (June 10, 2019): 250–56. http://dx.doi.org/10.31018/jans.v11i2.2028.

Full text

Abstract:

In Iron ore mining areas of Goa, water resources are polluted due to high turbidity and mineral colloids. For bioclarification of the turbidity, we need to identify some promising property of strains by which the strains of freshwater yeasts can be screened. This work presents a screening of freshwater yeast cultures, based on the complexity of colony margins. We performed screening of the wild aquatic yeasts isolated from different fresh water bodies of Goa on 2nd, 4th and 6th day of incubation respectively. Colony margins of sixteen different strains were studied for their fractality indexes and on comparison significant differences were observed among them. We report comparative analysis of five representative strains in this paper. Particularly strain Bchlm-1-2 showed high fractality index approximately 1410 on 6th day of incubation. This work provides quantitative scoring system of the morphological behavior of large number of strains. Our approach has the potential to improve the accuracy and speed to quantify and compare large number of isolates on the basis of their colony margins.

APA, Harvard, Vancouver, ISO, and other styles

33

Domingues, Rita B., Tânia P. Anselmo, Ana B. Barbosa, Ulrich Sommer, and Helena M. Galvão. "Nutrient limitation of phytoplankton growth in the freshwater tidal zone of a turbid, Mediterranean estuary." Estuarine, Coastal and Shelf Science 91, no. 2 (January 2011): 282–97. http://dx.doi.org/10.1016/j.ecss.2010.10.033.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Asaduzzaman, Md, Yoji Igarashi, Md Abdul Wahab, Md Nahiduzzaman, Md Jalilur Rahman, Michael J. Phillips, Songqian Huang, Shuichi Asakawa, Md Moshiur Rahman, and Li Lian Wong. "Population Genomics of an Anadromous Hilsa Shad Tenualosa ilisha Species across Its Diverse Migratory Habitats: Discrimination by Fine-Scale Local Adaptation." Genes 11, no. 1 (December 30, 2019): 46. http://dx.doi.org/10.3390/genes11010046.

Full text

Abstract:

The migration of anadromous fish in heterogenic environments unceasingly imposes a selective pressure that results in genetic variation for local adaptation. However, discrimination of anadromous fish populations by fine-scale local adaptation is challenging because of their high rate of gene flow, highly connected divergent population, and large population size. Recent advances in next-generation sequencing (NGS) have expanded the prospects of defining the weakly structured population of anadromous fish. Therefore, we used NGS-based restriction site-associated DNA (NextRAD) techniques on 300 individuals of an anadromous Hilsa shad (Tenualosa ilisha) species, collected from nine strategic habitats, across their diverse migratory habitats, which include sea, estuary, and different freshwater rivers. The NextRAD technique successfully identified 15,453 single nucleotide polymorphism (SNP) loci. Outlier tests using the FST OutFLANK and pcadapt approaches identified 74 and 449 SNPs (49 SNPs being common), respectively, as putative adaptive loci under a divergent selection process. Our results, based on the different cluster analyses of these putatively adaptive loci, suggested that local adaptation has divided the Hilsa shad population into two genetically structured clusters, in which marine and estuarine collection sites were dominated by individuals of one genetic cluster and different riverine collection sites were dominated by individuals of another genetic cluster. The phylogenetic analysis revealed that all the riverine populations of Hilsa shad were further subdivided into the north-western riverine (turbid freshwater) and the north-eastern riverine (clear freshwater) ecotypes. Among all of the putatively adaptive loci, only 36 loci were observed to be in the coding region, and the encoded genes might be associated with important biological functions related to the local adaptation of Hilsa shad. In summary, our study provides both neutral and adaptive contexts for the observed genetic divergence of Hilsa shad and, consequently, resolves the previous inconclusive findings on their population genetic structure across their diverse migratory habitats. Moreover, the study has clearly demonstrated that NextRAD sequencing is an innovative approach to explore how dispersal and local adaptation can shape genetic divergence of non-model anadromous fish that intersect diverse migratory habitats during their life-history stages.

APA, Harvard, Vancouver, ISO, and other styles

35

Utete, Beaven, Tamuka Nhiwatiwa, Blessing Kavhu, Samuel Kusangaya, Nyashadzashe Viriri, Accurate W. Mbauya, and Joshua Tsamba. "Assessment of water levels and the effects of climatic factors and catchment dynamics in a shallow subtropical reservoir, Manjirenji Dam, Zimbabwe." Journal of Water and Climate Change 10, no. 3 (March 2, 2018): 580–90. http://dx.doi.org/10.2166/wcc.2018.134.

Full text

Abstract:

Abstract Natural water level fluctuations have associated effects on water quality and resident aquatic communities, although their impacts are magnified if the dams have other non-seasonal designated multiple uses. Research demonstrates that excessive water level fluctuations impair ecosystem functioning, ultimately leading to shifts between clear-water and turbid states in shallow lakes. However, these data lack for Manjirenji Dam in Zimbabwe, thus hampering efforts towards effective freshwater resources management in the shallow reservoir. This study analyzed water levels and their fluctuations, and assessed the effects of climatic factors and catchment dynamics using a combination of historical and remote sensed data for the shallow Manjirenji Dam in Zimbabwe. Time series and multiple regression analysis were used to determine water level trends, and the influence of catchment and climatic components in Manjirenji Dam. Lake levels have increased since construction, though their non-significant seasonal variation in the Manjirenji Dam reflects the overlapping effects of catchment and climatic variables. Despite the inferred high stability and resilience, the high fluctuation widths expose the dam to hydrodynamic and climate shocks which have major ecological and conservation implications. A climate change based integrated water resources management approach is necessary for sustainable water resources utilisation in the Manjirenji Dam.

APA, Harvard, Vancouver, ISO, and other styles

36

Rosen, Timothy, and Y. Jun Xu. "Estimation of sedimentation rates in the distributary basin of the Mississippi River, the Atchafalaya River Basin, USA." Hydrology Research 46, no. 2 (July 13, 2013): 244–57. http://dx.doi.org/10.2166/nh.2013.181.

Full text

Abstract:

The Atchafalaya River Basin (ARB) is the largest distributary basin of the Mississippi River composing anastomosing channels, backwater swamps, freshwater marshes, and wetland forests. Sedimentation in the ARB has presented management issues concerning habitat changes from open water areas to bottomland hardwood forests. A thorough understanding of sediment transport and deposition in the basin is not only required for proper management of the ARB, but is crucial for regional sediment budgets that affect the Mississippi River Delta Plain. In this study, we calculated 31 years (1980–2010) of total suspended sediment (TSS) inflow and outflow of the Atchafalaya River to quantify the long-term sediment retention in the basin. We then estimated sedimentation rates in the basin by spatially relating the retention with changes of turbid water area derived from Landsat imagery. The study found an annual average TSS inflow of 54.0 megatonnes (MT) and an annual average TSS outflow of 48.7 MT, resulting in an average annual retention of 5.3 MT. Spatially derived mean sedimentation rates were estimated between 0.06 and 0.153 mm d−1. The spatial estimates for sedimentation proved promising and with more sediment data available could become an invaluable tool for managing the ARB in the future.

APA, Harvard, Vancouver, ISO, and other styles

37

Labat, Frédéric, Gabrielle Thiébaut, and Christophe Piscart. "Principal Determinants of Aquatic Macrophyte Communities in Least-Impacted Small Shallow Lakes in France." Water 13, no. 5 (February 26, 2021): 609. http://dx.doi.org/10.3390/w13050609.

Full text

Abstract:

Small shallow lakes (SSL) support exceptionally high and original biodiversity, providing numerous ecosystem services. Their small size makes them especially sensitive to anthropic activities, which cause a shift to dysfunctional turbid states and induce loss of services and biodiversity. In this study we investigated the relationships between environmental factors and macrophyte communities. Macrophytes play a crucial role in maintaining functional clear states. Better understanding the factors determining the composition and richness of aquatic plant communities in least-impacted conditions may be useful to protect these shallow lakes. We inventoried macrophyte communities and collected chemical, climatic, and morphological data from 89 least-impacted SSL widely distributed in France. SSL were sampled across four climatic ecoregions, various geologies, and elevations. Hierarchical cluster analysis showed a clear separation of four macrophyte assemblages strongly associated with mineralization. Determinant factors identified by distance-based redundancy analysis (db-RDA) analysis were, in order of importance, geology, distance from source (DIS, a proxy for connectivity with river hydrosystems), surface area, climate, and hydroperiod (water permanency). Surprisingly, at a country-wide scale, climate and hydroperiod filter macrophyte composition weakly. Geology and DIS are the major determinants of community composition, whereas surface area determines floristic richness. DIS was identified as a determinant in freshwater lentic ecosystems for the first time.

APA, Harvard, Vancouver, ISO, and other styles

38

Rochelle-Newall, E. J., V. T. Chu, O. Pringault, D. Amouroux, R. Arfi, Y. Bettarel, T. Bouvier, et al. "Phytoplankton diversity and productivity in a highly turbid, tropical coastal system (Bach Dang Estuary, Vietnam)." Biogeosciences Discussions 8, no. 1 (January 18, 2011): 487–525. http://dx.doi.org/10.5194/bgd-8-487-2011.

Full text

Abstract:

Abstract. The factors controlling estuarine phytoplankton diversity and production are relatively well known in temperate systems. Less however is known about the factors affecting phytoplankton community distribution in tropical estuaries. This is surprising given the economic and ecological importance of these large, deltaic ecosystems, such as are found in South East Asia. Here we present the results from an investigation into the factors controlling phytoplankton distribution and phytoplankton-bacterial coupling in the Bach Dang Estuary, a sub-estuary of the Red River system, in Northern Vietnam. Phytoplankton diversity and primary and bacterial production, nutrients and metallic contaminants (mercury and organotin) were measured during two seasons: wet (July 2008) and dry (March 2009). Phytoplankton community composition differed between the two seasons with only a 2% similarity between July and March. The large spatial extent and complexity of defining the freshwater sources meant that simple mixing diagrams could not be used in this system. We therefore employed multivariate analyses to determine the factors influencing phytoplankton community structure. Salinity and suspended particulate matter were important factors in determining phytoplankton distribution, particularly during the wet season. We also show that phytoplankton community structure is probably influenced by the concentrations of mercury species (inorganic mercury and methyl mercury in both the particulate and dissolved phases) and of tri-, di, and mono-butyl tin species found in this system. Freshwater phytoplankton community composition was associated with dissolved methyl mercury and particulate inorganic mercury concentrations during the wet season, whereas, during the dry season, dissolved methyl mercury and particulate butyl tin species were important factors for the discrimination of the phytoplankton community structure. Phytoplankton-bacterioplankton coupling was also investigated during both seasons. In the inshore, riverine stations the ratio between bacterial production and dissolved primary production was high supporting the hypothesis that bacterial carbon demand is supported by allochthonous riverine carbon sources. The inverse was true in the offshore stations, where BP:DPP values were less than 1, potentially reflecting differences in primary production due to shifting phytoplankton community diversity.

APA, Harvard, Vancouver, ISO, and other styles

39

Mitrovic, S. M., R. L. Oliver, C. Rees, L. C. Bowling, and R. T. Buckney. "Critical flow velocities for the growth and dominance of Anabaena circinalis in some turbid freshwater rivers." Freshwater Biology 48, no. 1 (December 11, 2002): 164–74. http://dx.doi.org/10.1046/j.1365-2427.2003.00957.x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Powers, Jarrod, Shannon K. Brewer, James M. Long, and Thomas Campbell. "Evaluating the use of side-scan sonar for detecting freshwater mussel beds in turbid river environments." Hydrobiologia 743, no. 1 (September 6, 2014): 127–37. http://dx.doi.org/10.1007/s10750-014-2017-z.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Mitrovic, S. M. "Vertical Disentrainment of Anabaena circinalis in the Turbid, Freshwater Darling River, Australia: Quantifying Potential Benefits from Buoyancy." Journal of Plankton Research 23, no. 1 (January 1, 2001): 47–55. http://dx.doi.org/10.1093/plankt/23.1.47.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Liu, Bingqing, Eurico J. D'Sa, and Ishan D. Joshi. "Floodwater impact on Galveston Bay phytoplankton taxonomy, pigment composition and photo-physiological state following Hurricane Harvey from field and ocean color (Sentinel-3A OLCI) observations." Biogeosciences 16, no. 9 (May 14, 2019): 1975–2001. http://dx.doi.org/10.5194/bg-16-1975-2019.

Full text

Abstract:

Abstract. Phytoplankton taxonomy, pigment composition and photo-physiological state were studied in Galveston Bay (GB), Texas (USA), following the extreme flooding associated with Hurricane Harvey (25–29 August 2017) using field and satellite ocean color observations. The percentage of chlorophyll a (Chl a) in different phytoplankton groups was determined from a semi-analytical IOP (inherent optical property) inversion algorithm. The IOP inversion algorithm revealed the dominance of freshwater species (diatom, cyanobacteria and green algae) in the bay following the hurricane passage (29 September 2017) under low salinity conditions associated with the discharge of floodwaters into GB. Two months after the hurricane (29–30 October 2017), under more seasonal salinity conditions, the phytoplankton community transitioned to an increase in small-sized groups such as haptophytes and prochlorophytes. Sentinel-3A Ocean and Land Colour Instrument (OLCI)-derived Chl a obtained using a red ∕ NIR (near-infrared) band ratio algorithm for the turbid estuarine waters was highly correlated (R2>0.90) to the (high-performance liquid chromatography) HPLC-derived Chl a. Long-term observations of OLCI-derived Chl a (August 2016–December 2017) in GB revealed that hurricane-induced Chl a declined to background mean state in late October 2017. A non-negative least squares (NNLS) inversion model was then applied to OLCI-derived Chl a maps of GB to investigate spatiotemporal variations of phytoplankton diagnostic pigments pre- and post-hurricane; results appeared consistent with extracted phytoplankton taxonomic composition derived from the IOP inversion algorithm and microplankton pictures obtained from an Imaging FlowCytobot (IFCB). OLCI-derived diagnostic pigment distributions also exhibited good agreement with HPLC measurements during both surveys, with R2 ranging from 0.40 for diatoxanthin to 0.96 for Chl a. Environmental factors (e.g., floodwaters) combined with phytoplankton taxonomy also strongly modulated phytoplankton physiology in the bay as indicated by measurements of photosynthetic parameters with a fluorescence induction and relaxation (FIRe) system. Phytoplankton in well-mixed waters (mid-bay area) exhibited maximum PSII photochemical efficiency (Fv∕Fm) and a low effective absorption cross section (σPSII), while the areas adjacent to the shelf (likely nutrient-limited) showed low Fv∕Fm and elevated σPSII values. Overall, the approach using field and ocean color data combined with inversion models allowed, for the first time, an assessment of phytoplankton response to a large hurricane-related floodwater perturbation in a turbid estuarine environment based on its taxonomy, pigment composition and physiological state.

APA, Harvard, Vancouver, ISO, and other styles

43

Matsuoka, A., S. B. Hooker, A. Bricaud, B. Gentili, and M. Babin. "Estimating absorption coefficients of colored dissolved organic matter (CDOM) using a semi-analytical algorithm for Southern Beaufort Sea (Canadian Arctic) waters: application to deriving concentrations of dissolved organic carbon from space." Biogeosciences Discussions 9, no. 10 (October 9, 2012): 13743–71. http://dx.doi.org/10.5194/bgd-9-13743-2012.

Full text

Abstract:

Abstract. A series of papers have suggested that freshwater discharge, including a large amount of dissolved organic matter (DOM), has increased since the middle of the 20th century. In this study, a semi-analytical algorithm for estimating light absorption coefficients of the colored fraction of DOM (CDOM) was developed for Southern Beaufort Sea waters using remote sensing reflectance at six wavelengths in the visible spectral domain corresponding to MODIS ocean color sensor. This algorithm allows to separate colored detrital matter (CDM) into CDOM and non-algal particles (NAP) by determining NAP absorption using an empirical relationship between NAP absorption and particle backscattering coefficients. Evaluation using independent datasets, that were not used for developing the algorithm, showed that CDOM absorption can be estimated accurately to within an uncertainty of 35% and 50% for oceanic and turbid waters, respectively. In situ measurements showed that dissolved organic carbon (DOC) concentrations were tightly correlated with CDOM absorption (r2 = 0.97). By combining the CDOM absorption algorithm together with the DOC versus CDOM relationship, it is now possible to estimate DOC concentrations in the near-surface layer of the Southern Beaufort Sea using satellite ocean color data. DOC concentrations in the surface waters were estimated using MODIS ocean color data, and the estimates showed reasonable values compared to in situ measurements. We propose a routine and near real-time method for deriving DOC concentrations from space, which may open the way to an estimate of DOC budgets for Arctic coastal waters.

APA, Harvard, Vancouver, ISO, and other styles

44

Eichner, Michael, and Kelly Garcia. "Increase in morbidity and mortality in a shipment of red-eared slider turtles (Trachemys scripta elegans)." Laboratory Animals 53, no. 6 (June 25, 2019): 634–40. http://dx.doi.org/10.1177/0023677219858166.

Full text

Abstract:

A cohort of captive-bred red-eared slider turtles, Trachemys scripta, was received from a commercial vendor. Shortly after arrival, several turtles presented as lethargic with subjectively pale skin and multifocal areas of cotton-like tufts in the mouth area and distal extremities. The water was treated with a commercial anti-fungal and anti-bacterial preparation of Victoria Green B and acriflavine. Despite treatment, 10 turtles were euthanized and others demonstrated persistent clinical signs. A live turtle was submitted to a commercial diagnostic laboratory for microbiologic and histologic evaluation. Seven cultures were obtained from this turtle and numerous organisms grew from each culture, including Flavobacterium sp. Blood film analysis demonstrated intracytoplasmic gamonts of Haemogregarina sp. within erythrocytes. On necropsy, internal organs appeared to be slightly more adhered within the coelomic cavity than normal. The urinary bladder was markedly distended with turbid, dark yellow urine. Microscopic evaluation of the tissues revealed significant parasitism with Myxidium sp., Spirorchis sp. and Neopolystoma orbiculare. No fungal organisms were identified on histology or grown in culture. While there are scattered reports of these pathogens in freshwater turtles, none of the cases reported describe such extensive co-infections. It is likely that complicated infection and shipping stress exacerbated clinical signs typically seen with these organisms. Efforts to minimize stress and administration of prophylactic antiparasitic agents during the acclimation period may aid in reducing the consequences of internal parasitism in aquatic turtles.

APA, Harvard, Vancouver, ISO, and other styles

45

Halder, Nilu. "Taxonomic diversity of macrandrous species of Oedogonium Link ex Hirn (Chlorophyceae: Oedogoniales) with emphasis on ecology from Hooghly, West Bengal." Brazilian Journal of Biological Sciences 5, no. 10 (2018): 443–60. http://dx.doi.org/10.21472/bjbs.051021.

Full text

Abstract:

The present paper includes detail taxonomic features of nine taxa of Oedogonium Link ex Hirn (Chlorophyceae: Oedogoniales) collected from Hooghly district, West Bengal, India. These taxa are Oedogonium bharuchae N.D. Kamat, Oedogonium cardiacum f. pulchellum Hirn, Oedogonium crispum var. pyriforme (Wittr. ex Hirn) A.K.M.N. Islam et P. Sarma, Oedogonium gunnii Wittr. ex Hirn, Oedogonium khannae f. minus Gonzalves et S.C. Jain, Oedogonium nanum Wittr. ex Hirn, Oedogonium pratense Trans., Oedogonium rivulare A. Br. ex Hirn and Oedogonium vaucheri A. Br. ex Hirn. All those taxa were found to grow epiphytically on the leaves and stems of submerged hydrophytes as filaments in quiet lentic freshwater bodies after the end of rainy season. Twelve limnological parameters like temperature, pH, DO, BOD, COD, NO3-N, PO43-, Cl-, free CO2, TDS, total hardness and turbidity of algal habitats were analyzed and found conducive for their occurrence and growth up to maturity (formation of fertile structures). The result of limnological study also indicated that all these species preferred to grow alkaline pH, less turbid and hard water. Studied limnological parameters recorded as water temperature: 17.5 oC-20 oC, pH range from 7.1-7.6, high dissolved oxygen (DO) concentration 6.4-7.2 mg.L^-1, BOD values < 20.0 mg.L^-1, moderate COD values and lower nutrient levels with other parameters like Cl-, free CO2, TDS, turbidity as 6.8-9.0 NTU and also hard nature of water ranged from 120-204 mg.L^-1.

APA, Harvard, Vancouver, ISO, and other styles

46

Miyake, Hiroshi, Shiho Honda, Jun Nishikawa, and Fatimah Md Yusoff. "Life Cycle of Edible Jellyfish Acromitus hardenbergi Stiasny, 1934 (Scyphozoa: Rhizostomeae) Inhabiting a Brackish-Water Environment." Animals 11, no. 7 (July 20, 2021): 2138. http://dx.doi.org/10.3390/ani11072138.

Full text

Abstract:

The edible jellyfish Acromitus hardenbergi Stiasny, 1934 is harvested throughout the year at the mouth of the Perak River, Malaysia. Although this species is an important fishery resource in the local area, limited biological studies have been carried out on it. The aim of the present study was to elucidate the life cycle of this unique brackish-water jellyfish in order to conserve the species and develop sustainable jellyfish fisheries. Mature medusae were collected at the mouth of the Perak River. Embryonic and larval development after fertilization was completed within 24 h until the planula stage and within 48 h until the polyp stage. Primary polyps had a long stalk with a small stolon at the base of the calyx. Fully developed polyps were bowl-or goblet-shaped but became an elongated stalk under starved conditions. Asexual reproduction was accomplished only by means of budding, and no podocysts were produced. Strobilation was mono-disc type. These characteristics may be adaptations to the dynamic environmental conditions in the estuary of the Perak River, where salinity fluctuates widely due to strong inflows of highly turbid freshwater coupled with tidal changes. This study suggests that polyps of A. hardenbergi expand their population not by podocysts, but by budding as quickly as possible and forming one large ephyra by mono-disc strobilation without the residuum, because the polyp cannot remain for a long time at its settlement place in the sediment-rich environment with drastic salinity change.

APA, Harvard, Vancouver, ISO, and other styles

47

De Sève, M. A. "Diatom bloom in the tidal freshwater zone of a turbid and shallow estuary, Rupert Bay (James Bay, Canada)." Hydrobiologia 269-270, no. 1 (October 1993): 225–33. http://dx.doi.org/10.1007/bf00028021.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Domingues, Rita B., Tânia P. Anselmo, Ana B. Barbosa, Ulrich Sommer, and Helena M. Galvão. "Light as a driver of phytoplankton growth and production in the freshwater tidal zone of a turbid estuary." Estuarine, Coastal and Shelf Science 91, no. 4 (March 2011): 526–35. http://dx.doi.org/10.1016/j.ecss.2010.12.008.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Cope, Jennifer, Jennifer Murphy, Amy Kahler, Daniel Gorbett, Ibne Ali, Brandi Taylor, Lisa Corbitt, et al. "A Primary Amebic Meningoencephalitis Case Associated with Rafting on an Artificial Whitewater River." Open Forum Infectious Diseases 4, suppl_1 (2017): S307—S308. http://dx.doi.org/10.1093/ofid/ofx163.714.

Full text

Abstract:

Abstract Background Naegleria fowleri is a climate-sensitive thermophilic ameba found in freshwater that causes primary amebic meningoencephalitis (PAM; 0–8 infections per year in the U.S.) when it enters the nose and migrates to the brain. Patient exposure to water containing the ameba typically occurs in warm freshwater lakes and ponds during recreational water activities. In June 2016, an 18-year-old woman died of PAM after traveling to North Carolina, where she participated in whitewater rafting on an artificial whitewater river. Methods To determine water exposures, we reviewed medical records and conducted interviews with family and individuals who had traveled with the case-patient. To further investigate the artificial whitewater river as a possible exposure source, we visited the whitewater facility and collected water, biofilm, and sediment samples from the facility and from the nearby natural river. We performed select water quality tests onsite and tested for the presence of N. fowleri by culture and real-time PCR in the laboratory. Results Interviews revealed that the case-patient’s most probable water exposure in the 10 days before becoming ill occurred while rafting on an artificial whitewater river during which she was thrown out of the raft and submerged underwater. The ~11.5 million gallons of water in the whitewater facility were filtered, subjected to UV light, and occasionally chlorinated. Heavy algal growth was noted. The free chlorine residual was 0.05 mg/L, turbidity was 6.7 NTU, and water temperature was 30°C in the whitewater facility during the site visit. All 11 water-related samples taken from the facility were positive for N. fowleri. Of 5 samples taken from the natural river, 1 sediment sample was positive for N. fowleri. Conclusion This investigation documents a novel exposure to an artificial whitewater river as the likely exposure causing PAM in this case. Conditions in the whitewater facility (warm, turbid water with little chlorine and heavy algal growth) rendered the water treatment ineffective and provided an ideal environment for N. fowleri to thrive. The combination of natural and engineered elements at the whitewater facility create a challenging environment to control the growth of N. fowleri. Disclosures All authors: No reported disclosures.

APA, Harvard, Vancouver, ISO, and other styles

50

Utami, Dwi Amanda, Lars Reuning, Maximillian Hallenberger, and Sri Yudawati Cahyarini. "The mineralogic and isotopic fingerprint of equatorial carbonates: Kepulauan Seribu, Indonesia." International Journal of Earth Sciences 110, no. 2 (January 18, 2021): 513–34. http://dx.doi.org/10.1007/s00531-020-01968-9.

Full text

Abstract:

AbstractKepulauan Seribu is an isolated patch reef complex situated in the Java Sea (Indonesia) and is a typical example for a humid, equatorial carbonate system. We investigate the mineralogical and isotopic fingerprint of Panggang, one of the reef platforms of Kepulauan Seribu, to evaluate differences to other carbonate systems, using isotope in combination with XRD and SEM analysis. A characteristic property of shallow water (< 20 m) sediments from Kepulauan Seribu is their increased LMC content (~ 10%) derived from some genera of rotaliid foraminifers and bivalves. The relative abundance of these faunal elements in shallow waters might be related to at least temporary turbid conditions caused by sediment-laden river runoff. This influence is also evidenced by the presence of low amounts of siliciclastic minerals below the regional wave base. Kepulauan Seribu carbonates are characterized by very low δ13C and δ18O values. This is related to the isotopically depleted riverine input. The δ13CDIC in riverine water is reduced by the contribution of 12C from riverside mangroves. Deep atmospheric convection and intensive rains contribute 18O-depleted freshwater in the river catchments, finally reducing salinity in the Java Sea. The depleted δ13C signature in carbonates is further enhanced by the lack of green algae and inorganic carbonates and abundance of coral debris. Low δ18O values in carbonates are favored by the high water temperatures in the equatorial setting. Since equatorial carbonates in SE Asia, including the Java Sea, are typically influenced by high turbidity and/or river runoff, the observed distinctively low isotope values likely are characteristic for equatorial carbonate systems in the region.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Turbid freshwaters'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles