Total Water Exchange Research Articles

Gaping behaviour of Blue mussels (Mytilus edulis) in relation to freshwater runoff risks

Shellfish grown for food are vulnerable to environmental contamination, potentially rendering them unsafe for human consumption. Non-invasive gape (valve openness) sensing allows in-situ monitoring of bivalve shellfish behaviours, such as feeding, that can result in exposure to contaminated waters. Sensors were attached to Blue mussels and deployed for 10 days on natural mussel beds in Dundrum Bay, Northern Ireland. Data showed a tidally synchronous behaviour pattern of high openness at high water and vice versa. It is likely that this is, at least in part, due to extreme salinity variation (1.8–33.6) resulting from near total water exchange with each tide in the bay. This behaviour is likely to infer a degree of protection from contaminants during periods of low water, a time at which runoff-derived pollutants are most concentrated.

Assessment of resources of the Varvara thermo-mineral water deposit, Pazardzhik District

In order to determine the resources of the Varvara thermo-mineral water deposit, a hydrogeological model has been created, determined by the Finite Difference Method (FDM). The model was developed in the mode of stabilized filtration. The Varvara deposit occupies an area of 2.4 km2 in the Pazardzhik District, located in Southern Bulgaria. The collector for those thermo-mineral waters are biotite and amphibole-biotite gneisses. The total water exchange in the system of the Varvara mineral water deposit is 26 l/s (2 260 m3/d). The regional resources of the deposit are 25 l/s (2 171 m3/d). The geothermal resources of the deposit have been estimated to be 4.98 MJ/s.

Gene expression profiling supports the welfare evaluation of rainbow trout (Oncorhynchus mykiss) reared under different environmental and management conditions in six commercial flow through systems

The species-appropriate treatment of fish is of great importance and requires the accurate assessment of the fish welfare. Aim of this study was to get a deeper insight into the welfare of rainbow trout (Oncorhynchus mykiss) during grow-out on six farms equipped with flow through systems, each providing different environmental (water supply, and -exchange, water quality) and management conditions (stocking density, feeding frequency). The mRNA levels of 91 genes involved in stress and immune responses were analysed using multiplex quantitative PCR and complemented with organ histopathology, blood glucose and lactate levels, organ somatic indices, external morphological damage, behaviour, as well as environmental and management conditions. The farms analysed revealed large differences in environmental and management parameters. Accordingly the expression profiles of distinct sets of genes and other welfare indicators differed significantly between farms. Generally, fish from farms with a high water supply and fast water exchange at lower stocking densities had lower levels of external morphological damage. Stocking density and the duration of a total water exchange in the tank revealed a significant impact on gene expression. Further, effects of water quality and immunological responses were observed. The gene expression profiles obtained provide a deeper insight on the stress and immune response influenced by different rearing conditions, and hence a more accurate status of trout welfare in aquaculture settings.

Fish welfare evaluation index (fWEI) based on external morphological damage for rainbow trout (Oncorhynchus mykiss) in flow through systems

Scientific studies concerning fish sentience and consumers requesting ethically produced food have raised the need to accurately determine fish welfare and to implement standardized protocols for comparable welfare assessments in aquaculture. This study aimed to evaluate reliable, practicable on-farm indicators and to establish a welfare evaluation index for rainbow trout (Oncorhynchus mykiss) during grow-out in flow through systems. Potential on-farm welfare indicators, assessed on nine different farms, included environmental- (water supply, −exchange, −quality) and management parameters (stocking density, feeding frequency), behavior and health observations (disease and low welfare indicating behaviors, social behavior, activity level), and external morphological damage (skin-, fin-, eye-, gill damage, skeletal deformities, emaciation). Principal component analysis followed by multiple linear regression showed that water supply, −supply per kg fish, duration of a total water exchange, nitrogen compounds, and activity level were the major predictors of external morphological damage. The direct and indirect effects of suboptimal rearing conditions resulted in external morphological damage, demonstrating external damage as highly relevant welfare indicators. External morphological damage, assessed using photographic images with different severity grades of impairment, forms a method that is easily and quickly applied at no material costs. Due to limited reliability and/or practicability of environmental, management and behavioral parameters the fish welfare evaluation index (fWEI) was solely based on external morphological damage. The fWEI summarizes the external morphological damage including prevalence and severity, resulting in categories of very good to poor welfare. The fWEI can be applied by fish farmers, veterinarians, certification and monitoring programs.

Influence of water exchange rates on fingerling production in Indian major carps in large outdoor concrete tanks

Influence of varied water exchange (total of 0%, 40%, 60%, 80% and 100% in four phases during three months) on fingerling production of Indian major carps-catla, rohu and mrigal under polyculture was evaluated in large outdoor concrete tanks (50 m2). Rearing density of 30 fry m−3 was used. Survival in the control tanks reduced during the 2nd month unlike the treatments, attributed to lack of water exchange in the tanks. While no marked variation in water quality was observed among the control and treatments, graded water exchange led to proportionate improvement in the fingerling performance in terms of survival and growth in the treatments. Harvested total lengths of fingerlings were similar in all, irrespective of varied exchange levels. Although no significant variation in net weight gain (NWG) and specific growth rate (SGR) were observed among the treatments during 1st and 2nd months of rearing in any of the species, these attributes increased significantly during 3rd month with higher water exchange in treatments. The harvested body weight (HBW) also increased significantly with increased exchange level. However, survival, HBW, NWG and SGR remained similar in all species between the 80% and 100% water exchange levels. Treatment with 80% water exchange had higher water productivity in terms of number and biomass production of fingerlings per unit (m−3) of TWU and CWU for which, the study recommended 80% to be the ideal total water exchange required for fingerling production of IMC in concrete tanks.

Water exchange in Van Phong bay, Khanh Hoa province by hydrodynamic model

The analysis of the average wind field from 1979 to 2018 showed that in the Van Phong bay area, the hydrodynamic process is mainly influenced by tidal currents when the frequency of weak wind accounts for a high proportion and the wind regime is controlled entirely by locality and less likely to alter tidal currents significantly. Based on the shallow water hydrodynamic finite element model (FEM), a two-dimensional hydrodynamic model has been developed for Van Phong bay to study hydrodynamic features, especially exchange capacity of seawater with the open sea. The results show that the daily average daily exchange of water in Van Phong bay is about 1,845.46 × 106 m3/day, equivalent to 34.7% water volume in the bay. In the rainy season, the typical daily average water exchange in Van Phong bay is about 2,136.04 × 106 m3/day, equivalent to 43.19% of the volume of water in the bay. In the dry season, the typical daily average total water exchange in Van Phong bay is about 1,825.56 × 106 m3/day, corresponding to 34.35% of water volume in the bay.

Scale cortisol is positively correlated to fin injuries in rainbow trout (Oncorhynchus mykiss) reared in commercial flow through systems

Suboptimal farm management can lead to (chronic) stress and can result in external morphological damage, which both can have deleterious effects on fish performance and welfare. This study is the first to investigate a potential correlation between chronic stress and the occurrence of external morphological damage in rainbow trout (Oncorhynchus mykiss) reared commercial flow through systems. To quantify chronic stress in eight different farms, scales of 10 fish per farm were sampled for scale cortisol analysis using UPLC-MS/MS. Measured external morphological damage of fish included damage to the eyes, skin and fins, as well as deformities and emaciation. Further, the influence of management (water supply, water supply per kg fish, total water exchange duration, average stocking density, feeding frequency) and water quality (oxygen, temperature, pH, ammonium, ammonia, nitrite, nitrate, turbidity) on chronic stress level and external morphological damage was assessed. Measured eye- and skin damage, deformities and emaciation occurred less frequently, while fin injuries were common and differed significantly in severity between farms. Results on all fish across farms showed a highly positive correlation between scale cortisol and total fin injury. A limited water supply, −supply per kg fish and −exchange as well as higher stocking densities and feeding frequencies resulted in a comparably reduced water quality, indicated by correlations with lower oxygen levels, higher levels of nitrogen compounds, higher temperature and turbidity. After conducting a principal component analysis, multiple linear regression models showed that scale cortisol was mainly predicted by total fin injury, temperature and the pH, ammonia and nitrite component. Total fin injury was majorly predicted by the management component concerning water supply, −supply per kg fish and −exchange duration as well as by stocking density, scale cortisol, the pH, ammonia and nitrite component and feeding frequency. Findings on scale cortisol support fin injuries to be an important welfare issue and suitable on-farm welfare indicator. Higher scale cortisol levels and higher fin injuries, directly and indirectly influenced by farm management, are indicative for impaired welfare and support the necessity of reducing chronic stress and the occurrence of fin injuries in aquaculture settings.

S0188 Complete Elimination of Gas Insufflation by Insertion and Withdrawal Water Exchange Reduces Post-Colonoscopy Flatulence: A Double Blinded Observational Study

INTRODUCTION: Conventional colonoscopy generates aerosol, which disseminates bacteria [Chapman, BMJ 2001] during and after the procedure, in part related to air insufflation-induced flatus. SARS-CoV-2 is present in the gut tissue and feces. During the COVID-19 pandemic, mitigation of aerosol-mediated infection is desirable. Total water exchange colonoscopy (TWEC -- insertion and withdrawal water exchange) eliminates the need for air insufflation. We test the hypothesis that TWEC reduces flatus compared with other methods that rely on gas insufflation. METHODS: This study was a retrospective analysis of prospectively collected data from a sample of outpatient screening and surveillance colonoscopies at a single endoscopy unit over a 2-month period. Six colonoscopists used different techniques (Table 1). Since evaluation of flatus during colonoscopy cannot be blinded, we assumed that flatus after colonoscopy during the recovery period is an accurate reflection of flatus peri-procedurally, and has the distinct advantage that blinded assessment was feasible. Data on flatulence during recovery were collected by a nurse blinded to colonoscopy techniques. Colonoscopists did not know which patients were selected for flatus monitoring. Sample size calculation [TWEC 1%, other intervention 39%] yielded 14 per group, 28 total per colonoscopist. IRB approval was waived because recovery monitoring was a routine part of post-colonoscopy care. RESULTS: 168 consecutive colonoscopies (28 per endoscopist) were identified. Patient age, BMI and procedure indication (screening/surveillance) were comparable (data not shown). Compared to techniques where gas was used during any part of the examination, significantly fewer patients (P < 0.01) were observed to pass flatus during recovery in the TWEC group (Table 2). CONCLUSION: In a recent letter to the editor (Adv Dig Med, in press) we expressed the opinion that TWEC (avoiding gas insufflation) seems to be a logical, cost-conscious, and easily implemented safeguard to reduce SARS-CoV-2 transmission in addition to more widely accepted protective measures. We now provide double blinded observational data to support this opinion. By eliminating the use of gas during colonoscopy, TWEC appears to reduce peri-procedural flatus, and by inference, aerosol formation. This may have potential impact on mitigating the risks of aerosol-induced infection during colonoscopy in the era of COVID-19.Table 1Table 2

Total water exchange colonoscopy to mitigate infection risks due to aerosolization during colonoscopy

Total water exchange colonoscopy to mitigate infection risks due to aerosolization during colonoscopy

Terminalia catappa improves growth performance and survival of the Amazon leaf fish ( Monocirrhus polyacanthus ) larvae submitted to handling stress

The almond Terminalia catappa leaf extract has been used to prevent diseases and improve breeding in various fishes; however, their effects on the leaf fish Monocirrhus polyacanthus larviculture are unknown. We evaluated the effect of almond leaf extract on growth performance and survival of leaf fish larvae submitted to handling stress. Five concentrations of aqueous extract of almond leaf (0.25, 0.50, 0.75, 1.00 and 1.25 g/L) were evaluated with five replicates. Leaf fish larvae (15 larvae/L 0.1 cm and 0.001 g) were fed 100 Artemia nauplii per larvae twice a day along 15 days and then submitted to handling stress of total water exchange and T. catappa extract replacement. Untreated fish were used as control. The stressful management caused lower survival rate for larvae in the control group (22.2Â ± 3.14%, p < .05). The best weight gain (5.70Â ± 0.20 g), specific growth rate (10.80Â ± 0.24%/day), length (0.31Â ± 0.17 cm) and survival (100.00Â ± 0.00%) were obtained with 0.75 g/L T. catappa (p < .05). The water quality parameters (pH and total ammonia) showed increased values for the higher concentrations of aqueous extract. The use aqueous leaf extract of T. catappa reduces mortality and improves growth performance of leaf fish larvae. It is suggested the use of T. catappa as a growth promoter for leaf fish larvae.

Interannual Variability of Water Exchange Anomalies Between the Northern, Middle and Southern Caspian Based on Satellite Altimetry Data

The paper presents the results of estimation of interannual and seasonal variability of water exchange between the Northern, Middle and Southern Caspian Sea based on the TOPEX/Poseidon and Jason–1/2/3 satellite altimetry data. The boundaries between the Caspian Sea sub-basins were taken along the 133 and 209 tracks of the satellites. Temporal variability of surface geostrophic velocities directed perpendicular to the tracks showed that positive values correspond to the southeast direction of the currents, negative values correspond to the northwest direction. It is clearly seen that the main water exchange associated with the Volga River runoff is concentrated along the western coast of the Caspian Sea. In this area, anomalies of geostrophic velocities exceed 20 cm/s. Total water exchange anomalies through the 133 and 209 tracks show seasonal variability with an amplitude up to ±18x105 m3/s for track 133 (a line between the Northern and Middle Caspian) and ±11x105 m3/s for track 209 (a line between the Middle and Southern Caspian). The maximum values of water exchange anomalies were observed in 1993, 1994 and 2012 through 133 track (±16-18x105 m3/s) and in 1993, 1996 and 1997 (±11x105 m3/s) through 209 track.

The influence of slope collapse on water exchange between a pit lake and a heterogeneous aquifer

Due to the increase in open pit mining, pit lakes have become common surface water features, posing a potential risk to subsurface aquifer. In this study, a pit lake–groundwater interaction model is built based on the general program MODFLOW with the LAK3 package. For the first time, the effects of lake-slope collapse and aquifer heterogeneity on pit lake–groundwater interactions are analyzed by dividing the lake into six water exchange zones based on the aquifer lithology and groundwater level. Our investigation and simulations reveal a total water exchange from groundwater to the lake of 349000 m3/a without collapse of the pit lake slope, while the total net water exchange under slope collapse conditions is 248000 m3/a (i.e., a reduction of 1.40-fold). The monthly net water exchange per unit width from groundwater to the lake reaches the largest in April, shifting to negative values in zone IV from June to August and in zone Vin June and July. Moreover, the monthly net water exchange per unit width decreases from north to south, and the direction and magnitude of water exchange are found to depend on the hydraulic gradients between the lake and groundwater and the hydraulic conductivity of the slope collapse.

Development of a finite volume two-dimensional model and its application in a bay with two inlets: Mobile Bay, Alabama

The purpose of this study was to develop a two-dimensional shallow water flow model using the finite volume method on a combined unstructured triangular and quadrilateral grid system to simulate coastal, estuarine and river flows. The intercell numerical fluxes were calculated using the classical Osher-Solomon's approximate Riemann solver for the governing conservation laws to be able to handle wetting and drying processes and to capture a tidal bore like phenomenon. The developed model was validated with several benchmark test problems including the two-dimensional dam-break problem. The model results were well agreed with results of other models and experimental results in literature. The unstructured triangular and quadrilateral combined grid system was successfully implemented in the model, thus the developed model would be more flexible when applying in an estuarine system, which includes narrow channels. Then, the model was tested in Mobile Bay, Alabama, USA. The developed model reproduced water surface elevation well as having overall Predictive Skill of 0.98. We found that the primary inlet, Main Pass, only covered 35% of the fresh water exchange while it covered 89% of the total water exchange between the ocean and Mobile Bay. There were also discharge phase difference between MP and the secondary inlet, Pass aux Herons, and this phase difference in flows would act as a critical role in substances’ exchange between the eastern Mississippi Sound and the northern Gulf of Mexico through Main Pass and Pass aux Herons in Mobile Bay.

Novel Modification of Insertion Water Exchange to Total Water Exchange Increases Adenoma Detection

Novel Modification of Insertion Water Exchange to Total Water Exchange Increases Adenoma Detection

Effect of suspended kelp culture on water exchange as estimated by in situ current measurement in Sanggou Bay, China

Water exchange between Sanggou Bay and the Yellow Sea in China was estimated based on current profiles measured by four bottom-mounted Acoustic Doppler Current Profilers at the entrance of the bay during the kelp seeding and kelp harvesting periods. Hydrodynamics in the bay were dominated by tidal currents, especially semi-diurnal constituents. The effect of suspended kelp culture on the water exchange was investigated in terms of the tidal flux and tidal prism of the bay during a semi-diurnal period. Suspended kelp culture was found to significantly affect water exchange by changing the spatial pattern of the tidal flux but not the tidal prism. The inward tidal flux was reduced by 10% to 70% in the upper layers in the kelp seeding to kelp harvesting periods. Meanwhile, the inward tidal flux was increased by 10% to 140% in the lower layers. The mean inward tidal prism was 2.31×108m3 and 2.17×108m3 during the kelp seeding period and kelp harvesting period, respectively. Comparing with previous numerical simulations, our results did not show a prominent reduction in total water exchange across the entrance of the bay by suspended kelp culture.

More than feasibility - total water exchange colonoscopy

More than feasibility - total water exchange colonoscopy

Study of the hydrodynamical processes in the Boka Kotorska Bay with a finite element model

Boka Kotorska Bay, located in the southeastern Adriatic Sea along the Montenegro coastline, is a complex morphological structure, consisting of three embayments. They are connected and interact with the sea through narrow straits and the bay can be considered one of the main freshwater inputs into the southern Adriatic Sea. In the framework of the ADRICOSM-STAR project, a hydrodynamical model of this region provided results that are compared with CTD data and hydrodynamic scenarios are discussed for the bay. A finite element coastal model nested in a finite difference model that runs on the Adriatic Sea has been used to reproduce the complex morphology of the bay. Hydrodynamic modeling allows studying the main characteristics of this bay, identifying it as a Region of Freshwater Influence (ROFI). The freshwater input coming from the numerous sources present in the bays can strongly modify temperature, salinity and current patterns. The computation of the buoyancy ratio of the thermal and haline buoyancy flux showed that the Kotor and Morinj Bays experience a major effect of surface heating in summer, while the rest of the bay seems to be mostly affected by freshwater influence from precipitation and river discharge. An average estuarine situation is seen, presenting a surface outflow and a bottom inflow of water. Specific hydrodynamic processes can be detected in the channels that connect the different sub-basins of the Boka Kotorska Bay. Moreover, the computation of the Kelvin number in correspondence of the internal straits suggests classifying the Kotor and Morinj Bays differently from the outermost areas. The innermost Kotor and Morinj Bays, generally exchange little water with the sea and they have high values of residence times. However, their fresh water springs and rivers have the highest discharges that can change abruptly the picture with increase of the total water exchange between the bay and the sea.

Thermoregulation and water balance in fat-tailed sheep and Kacang goat under sunlight exposure and water restriction in a hot and dry area

The objective of this study was to analyze differences in thermoregulation and water balance under conditions of heat load and water restriction between fat-tailed sheep (S) and Kacang goats (G). The daily intakes of food and water, daily outputs of urine and feces, rectal temperature, respiration rates, hematocrit values and plasma volumes of five shorn S and five G were determined over 10 days of four consecutive experimental conditions: (1) indoor – unrestricted water; (2) indoor – restricted water; (3) 10 h sunlight exposure – unrestricted water; and (4) 10 h sunlight exposure – restricted water. There was a 6- to 7-day adjustment period between two consecutive conditions. The study was conducted during the dry season. The animals were placed in individual cages, fed chopped native grass ad libitum and had free access to a urea–molasses multi-nutrient block. Under sunlight exposure with unrestricted water availability, S and G record an increase in the maximum rectal temperatures from 39.2°C to 40.2°C and from 39.9°C to 41.8°C, respectively. The thermoregulatory strategy used by S for maintaining a lower rectal temperature mostly depends on increasing the respiration rate as the main cooling mechanism. On the other hand, G apparently used sweating as the predominant mechanism for cooling. Moreover, G seemed to be more tolerable to higher heat storage and body temperature than S with a significant increase in plasma volume (P < 0.01), and this may be beneficial to the animals for the prevention of water loss. Under restricted water condition in either indoor or outdoor environment, both species decreased their plasma volume significantly, but rectal temperatures were relatively maintained. In all experimental conditions, the daily total water exchanges (ml/kg0.82 per day) of S were significantly higher than G (P < 0.01). However, when the percentages of the total daily water exchange were considered, the water lost through urination (38% to 39%), defecation (11% to 14%) and evaporation (46% to 49%) by S and G was not significantly different. Therefore, the results from this study clearly showed that S and G have different homeostatic strategies for the regulation of body temperature and fluid to cope with heat load and water restriction. These differences may have an important impact on the production management of S and G.

Effects of Temperature on the Growth of Golden Shiners in Aquaria

AbstractControl of fish size is critical to baitfish production and marketing, and temperature is a major factor affecting fish growth. Temperature‐dependent growth models were developed for juvenile golden shiners Notemigonus crysoleucas. Two 10‐week trials with two juvenile sizes (0.5 and 1.0 g) were conducted in a flow‐through aquarium system to determine the growth response to temperature. Four temperature treatments (15, 20, 25, and 30°C) were randomly assigned to twenty 110‐L glass aquaria; 20 fish were stocked into each aquarium. Each aquarium received a constant inflow of water at a rate of approximately 200 mL/min, equivalent to a total water exchange every 9 h. Fish were hand fed twice daily to apparent satiation with a commercial minnow feed (32% crude protein) that had been crumbled and sieved (particle size &lt; 0.85 mm). Fish in each aquarium were batch weighed and counted every 2 weeks to document growth and survival. Average survival across treatments ranged from 93% to 96% for 0.5‐g fish and from 91% to 97% for 1.0‐g fish, and survival was not significantly different among treatments (P &gt; 0.05). Quadratic equations were derived to predict maximum rates of total weight growth (ΔW, g/d) and total length growth (ΔL, mm/d) from temperature. Under study conditions, ΔW was obtained at 26.0°C for 0.5‐g fish and at 24.1°C for 1.0‐g fish; ΔL was obtained at 26.0°C for 0.5‐g fish and at 23.9°C for 1.0‐g fish. Documenting the relationship of temperature to growth could lead to improvements in baitfish farming techniques. A combination of pond and tank culture would make it possible to extend the growing season or to stockpile quantities of different sizes of fish to meet market requirements.

Effects of two louisiana marsh management plans on water and materials flux and short-term sedimentation

The impact of two coastal Louisiana marsh management plants on water and materials flux, shortterm sedimentation, and several soil parameters was evaluated between May 1989 and January 1990. The study was carried out in the Fina-Laterre Marsh Management Area and the Rockefeller State Wildlife Refuge in managed and unmanaged areas. Water and material flux was measured each two hours during twelve 48 h flux studies, and net fluxes per m2 of drainage area were calculated for water, total suspended sediments, salinity, NO3+NO2, PO4, and NH4. Short-term sedimentation was measured as the weight of material deposited over 2–4 week intervals on petri dishes placed on the marsh surface. The managed sites experienced considerable reductions in total water exchange, leading to reductions in net material exchanges. When expressed on a per m2 basis, the managed wetlands are much less tightly coupled to the surrounding estuary compared to unmanaged areas. Within the context of a general decrease of exchange, the two managed areas on average export materials to the estuary. In the managed areas, the results suggest that management can lead to reduced salinity and a loss of sediments and nutrients. Short-term sedimentation was less at the managed areas; expressed as g m−2d−1, total sedimentation rates were 0.57 for Fina managed, 1.02 for Fina unmanaged, 1.68 for Rockefeller managed, and 3.82 for Rockefeller unmanaged. Soil P was lower and soil organic matter was higher at the managed areas. Organic matter in the soil was low compared with recently deposited material, suggesting that most organic matter deposited on the surface of the marsh is lost through decomposition. Reduction of flooding during storm events is the likely mechanism leading to reduced sedimentation on the marsh surface in the managed areas.