Changes In Dissolved Oxygen Concentration Research Articles

Effects of dissolved oxygen on the corrosion-related unidentified deposit formed of 304 SS in the flow accelerated zone under the simulated secondary water chemistry

Effects of dissolved oxygen (DO) on the deposition characteristics of corrosion-related unidentified deposit (CRUD) were investigated by using 304 stainless steel micro-orifices. The main results indicate that the change of DO concentration resulted in a change of the composition of the outermost deposition layer. The DO concentration amplifies/diminishes the porosity in CRUD effect by changing the rate of ion transport. Meanwhile, the electrokinetic effect is weakened by the decrease of the thickness of the electric double layer, which is caused by the dissolution of Cr ions increased by increasing the DO concentration. Meanwhile, the chromium ion concentration increases with the dissolved oxygen concentration, which leads to a decrease in the thickness of the electric double layer, weakening the electrodynamic effect. The above results in the thickness and width of CRUD in the flow acceleration zone vary in varying degrees. This suggests that the deposition process of CRUD occurs under the mechanism of mass transfer and electrokinetic mechanism.

Photocatalytic degradation process of antibiotic sulfamethoxazole by ZnO in aquatic systems: a dynamic kinetic model based on contributions of OH radical, oxygenated radical intermediates and dissolved oxygen

The photocatalytic degradation process of sulfamethoxazole (SMX) using ZnO in aquatic systems has been systematically studied by varying initial SMX concentration from 0 to 15 mgL−1 , ZnO dosage from 0 to 4 gL−1 and UV light intensity at the light source from 0 to 18 W(m-lamp length)−1 at natural pH. Almost complete degradations of SMX were achieved within 120 min for the initial SMX concentration ≤15 mgL−1 with ZnO dosage of 3 gL−1 and UV light intensity of 18 W(m-lamp length)−1. The photocatalytic degradation process was found to be interacted with the dissolved oxygen (DO) consumption. With oxygen supply through the gas-liquid free-surface, the DO concentration decreased significantly in the initial SMX degradation phase and increased asymptotically to the saturated DO concentration after achieving about 80% SMX degradation. The change in DO concentration was probably controlled by the oxygen consumption in the formation of oxygenated radical intermediates. A novel dynamic kinetic model based on the fundamental reactions of photocatalysis and the formation of oxygenated radical intermediates was developed. In the modeling the dynamic concentration profiles of OH radical and DO are considered. The dynamics of SMX degradation process by ZnO was simulated reasonably by the proposed model.

Machine learning-based prediction of seasonal hypoxia in eutrophic estuary using capacitive potentiometric sensor

A hypoxia occurred in eutrophic estuary was predicted using long short-term memory (LSTM) model with prediction time steps (PTSs) of 0, 1, 12, and 24 h. A capacitive potential (CP), which provides quantitative information on dissolved oxygen (DO) concentration, was used as a predictor along with precipitation, tide level, salinity, and water temperature. First, annual changes in DO concentration were clustered in three phases of annual DO trends (oversaturation, depletion, and stable) using k-means clustering. CP was the most influential variable in clustering the DO phases. The LSTM was implemented to predict the DO phases and hypoxia occurrences. In the simultaneous prediction of the depletion phase and hypoxia occurrence with a 12 h PTS, the accuracy was 92.1% using CP along with other variables; it was 3.3% higher than that achieved using variables other than CP. In the case of predicting the depletion phase and hypoxia non-occurrence using CP along with other variables, the accuracy was 61.1%, which was 5.5% higher than that when CP was not used. When using CP along with other variables, the total accuracy was highest for all PTS. Overall, the utilization of CP and machine learning techniques enables accurate predictions of both short-term and long-term hypoxia occurrences, providing us with the opportunity to proactively respond to disasters in aquaculture and environmental management due to hypoxia.

Dissolved oxygen estimation in aquaculture sites using remote sensing and machine learning

Dissolved oxygen (DO) is one of the most critical parameters for aquaculture, as it is vital for all living organisms. The survival, growth and food intake of fish is directly affected by changes in DO concentration. Therefore, the systematic and continuous monitoring of DO is of crucial importance for proper production management. DO does not change the optical properties of water, so it is impossible to estimate its concentration directly from the reflection values of satellite sensors. However, several studies have suggested that it can be estimated indirectly, based on its correlation with other parameters such as chlorophyl-a (chl-a) and sea surface temperature (SST). The present study aims to integrate satellite data, along with in-situ observations to bring forth innovative approaches on how DO can be estimated and monitored on large scale near aquaculture facilities. In this context we exploited daily CMEMS data (chl-a and SST) along with in-situ data (DO) to train a support vector regression (SVR) model. Our in-situ dataset included daily DO measures from Agrilia fish farm in Lesvos for the year 2021. The accuracy of our model was tested using the value of Mean Absolute Error (MAE) and Root Mean Squared Error (RMSE). Our preliminary results indicate that our model performs well locally with promising scalability, which paves the way for the development of real-time monitoring systems for aquaculture.

Nitrogen and boron-doped reduced graphene oxide chemiresistive sensor for real-time monitoring dissolved oxygen in biological processes

We developed a nitrogen and boron-doped reduced graphene oxide (N, B-HRGO) based chemiresistive sensor to measure dissolved oxygen (DO) in a complex biological medium. The N, B-HRGO modified interdigitated micro electrode arrays (IDE) constructed as a chemiresistor by the drop-cast method. A silicon based fluorinated oxygen permeable membrane protects the surface from the interference and provides a specificity to the sensor. The sensor responded to the DO concentration changes due to modulated surface charge carrier concentration by the adsorbed dissolved oxygen molecule (Oad). For DO concentration range 0–5 mg.L−1 there was nearly 80% change in response for the sensor with membrane. The resistance of the N, B-HRGO film was measured at different DO concentrations in KNO3 solution and during the growth of Amycalotopsis methanolica bacterial fermentation. The study showed that the sensor is sensitive to the oxygen present in the solution and can detect DO consumption in a complex fermentation medium. The effect of water and the electrolyte salt ions present in the electrolyte was studied in detail. It was observed that the adsorption of water molecule increases the sensor resistance, whereas the salt ions have negligible effect on the sensor response. Because of the simple electrode structure, this chemiresistive sensor can measure DO in the micro bioreactors with a volume of few microliters. The N, B-HRGO chemiresistive sensor can also be used for DO measurement in other bioprocess applications.

Preliminary Study on the Dissolved Oxygen Recovery Process in Freshwater Ecosystems under the Coupling Effect of Oxygen-Consuming Pollutants and Temperature

Widespread deoxygenation of the oceans has caused great concern, but few large studies of changes in dissolved oxygen (DO) concentrations in freshwater ecosystems and the factors driving such changes have been performed. Here, DO and oxygen-consuming pollutant (OCP) data for freshwater ecosystems in China from 2008 to 2018 were used to assess changes in DO concentrations and the mechanisms involved. DO concentrations in freshwater ecosystems in China recovered markedly in the study period. The DO concentrations have linearly increased (R2 = 0.95, p < 0.01) in that period. The chemical oxygen demand (CODMn) and NH3–N concentrations have significantly decreased [polynomial fitted curves (n = 2): R2 = 0.77, p < 0.01 for CODMn and R2 = 0.95, p < 0.01 for NH3–N]. The polynomial curves fitted to the CODMn, NH3–N, and DO data indicated that there are thresholds for oxygen-rich and deoxygenation processes dominated by OCPs in freshwater ecosystems. Decreasing OCP concentrations will not promote DO recovery if the CODMn and NH3–N concentrations are <4 and <0.4 mg L–1, respectively. The effect of temperature on the DO concentration in freshwater was obscured by inputs of large amounts of OCPs. The discovery of thresholds for the effect of OCPs led to the division of the DO recovery process into stages by increases in the temperature.

Microfluidic-Based Bacterial Molecular Computing on a Chip

Biocomputing systems based on engineered bacteria can lead to novel tools for environmental monitoring and detection of metabolic diseases. In this paper, we propose a Bacterial Molecular Computing on a Chip (BMCoC) using microfluidic and electrochemical sensing technologies. The computing can be flexibly integrated into the chip, but we focus on engineered bacterial AND Boolean logic gate and ON-OFF switch sensors that produces secondary signals to change the pH and dissolved oxygen concentrations. We present a prototype with experimental results that shows the electrochemical sensors can detect small pH and dissolved oxygen concentration changes created by the engineered bacterial populations’ molecular signals. Additionally, we present a theoretical model analysis of the BMCoC computation reliability when subjected to unwanted effects, i.e., molecular signal delays and noise, and electrochemical sensors threshold settings that are based on either standard or blind detectors. Our numerical analysis found that the variations in the production delay and the molecular output signal concentration can impact on the computation reliability for the AND logic gate and ON-OFF switch. The molecular communications of synthetic engineered cells for logic gates integrated with sensing systems can lead to a new breed of biochips that can be used for numerous diagnostic applications.

Organic Removal Treatment Using Microbubble Generator (MBG) in Eutrophic Disorder Condition

The Techno Park basin, built as an extension of a small tributary of the Code River primarily acts as a retention basin for runoff during the rainy season. It improves the quality of water that has been degraded by domestic wastewater discharge from the surrounding community. Therefore, this study aims to assess the extent to which water quality of the basin can be improved with aeration technology. The aeration technology is a Microbubble Generator (MBG) built using a 100 Watts submersible pump with three horizontal nozzles at a depth of 40 cm from the water surface. Furthermore, the profiles of dissolved oxygen (DO) concentration were measured at the basin’s inlet and outlet, as well as the depths of 1 m below surface water and the bottom of the basin. Diurnal DO was measured to investigate the causes of supersaturation. The aeration performance was also determined from the COD parameters at the inlet and outlet. Discharge measurements were then conducted on the tributary/drainage channel to the inlet basin. The result showed that the DO supersaturation concentration has been attributed to the contribution of photosynthesis from phytoplankton such as algae. Furthermore, no change in DO concentration was observed in a range of 1 m depth from the surface of the water to the bottom (0.3 - 0.14 mg-DO/l). In this eutrophic state, DO increased exponentially during the daytime hours and then decreased during the night. The daily measurement showed an increase in the average DO of 2.31 mg/l (standard deviation of 1.56 mg/l), with average CODinlet fluctuations of 18.79 mg/l (standard deviation of 13.56 mg/l) and average CODoutlet of 14.38 mg/l (standard deviation 2.94 mg/l). Due to additional DO concentration coming from eutrophication during daylight, it was not possible to make a precise assessment of the effectiveness of the MBG aerator.

DETERMINING THE EFFECT OF CHANGING CHANNEL GEOMETRY OF IRRIGATION CANALS ON DISSOLVED OXYGEN CONCENTRATION

Dissolved oxygen (DO) is an important water quality parameter. It is considered the most important parameter. DO concentration in water is affected by different parameters such as volume flow rate, water velocity, and re-aeration rate. Those parameters are directly affected by the geometry of the waterway. Thus, studying the impact of changing channel geometry on DO is very important. Many researchers studied the effect of influential parameters on water quality variables but the influence of channel geometric parameters on DO was not studied thoroughly before. This research aims to study the effect of changing channel geometry on DO concentration. The DO is modeled along the channel using Streeter-Phelps equation. Studied geometric parameters are water depth, bottom width, side-slopes, and channel length. The case study is taken as Sheikh Zayed canal in Egypt. Sheikh Zayed canal is responsible for irrigating Toshka land in the Western Desert of Egypt. It is also responsible for increasing the cultivated area of Egypt by about 550,000 feddans. It was found that the DO concentration is greatly affected by changing the geometry of the canal, as the canal geometry directly influences the flow velocity as well as reaeration rate. The percentage change of DO concentration with every geometry parameter is for length 6.8%, bed width 1.8%, water depth 4%, and side slopes 1.4%.

Variations in dissolved O2 in a Chinese lake drive changes in microbial communities and impact sedimentary GDGT distributions

Glycerol dialkyl glycerol tetraethers (GDGTs) are widespread but unique membrane-spanning lipids of many Archaea and some Bacteria. However, their specific biological sources and the associated environmental controls on their distribution remain unclear, especially in lacustrine settings, hindering our understanding of these compounds and their application as environmental proxies. Here we investigated the GDGT distributions across a large bottom water dissolved oxygen (DO) gradient (0.10–7.20 mg/L) using surface sediments of Lake Yangzonghai, a warm monomictic lake in southwestern China. We show that the distributions of both branched (br) and isoprenoidal (iso) GDGTs co-vary significantly with bottom water DO concentration. The relative abundances of tetramethylated brGDGTs, 5-methyl penta- and hexamethylated brGDGTs and isoGDGT-0 show a stepwise increase as bottom water DO concentration decreases. On the other hand, the relative abundances of 6-methyl penta- and hexamethylated brGDGTs and crenarchaeol exhibit a stepwise decline with a decrease in bottom water DO concentration. Genetic data indicate these DO-induced changes in GDGT parameters are related to changes in the bacterial and archaeal communities across the oxycline in the lake. For example, the high abundance of isoGDGT-0 in low DO samples coincides with a high abundance of methanogenic archaea and Bathyarchaeota. We propose that brGDGT-producing bacteria might include a diversity of other phyla in addition to the proposed source organism acidobacteria; different groups of anaerobic and aerobic bacteria are likely to contribute to the increased abundance of 5-methyl brGDGTs and 6-methyl brGDGTs in low and high DO zones, respectively. Consequently, the MBT′ and MBT′6ME brGDGT indices display strong correlations with DO concentration. Importantly, the MBT′5ME index is not significantly influenced by changes in DO concentration, suggesting that this index might be more resilient to these impacts and more suitable to reconstruct temperature in lake systems.

Distribution of DO (Dissolved Oxygen) and BOD (Biological Oxygen Demand) in the Waters of Karimunjawa National Park using Two-Dimensional Model Approach

Massive mangrove conversion into intensive pond farming has become environmental problem in Kemujan Island and Karimunjawa Island which affect the water quality. This research aimed to examine the dispersion of DO and BOD related to the current pattern in the seas west of Kemujan Island and Karimunjawa Island by using two-dimensional modelling simulations. Quantitative and descriptive methods were used to provide interpretation and analysis of the modelling simulation results. Modelling simulations were conducted in September 2019. The validation results show that the model and the field measurements has a very good. The results show that the current characteristics are dominated by tidal current, which moves westward with an average magnitude of 0.078 m/s. Furthermore, divergence, convergence and turbulence are also identified. Based on the simulation results, the prediction of DO and BOD concentrations fluctuate in Lagoon Mrican. During spring tide, the DO concentration changes from 7.95 - 8.1 mg/L into 8.55 - >9.45 mg/L and during neap tide, it changes from 8.55 - 8.7 mg/L into 9.15 - >9.45 mg/L. On the other hand, the BOD concentration increases from 0 - 0.08 mg/L to 0.88 - 0.96 mg/L during spring tide and neap tide.

Variability of Dissolved Oxygen in the Bottom Layer of the Southern Senegalese Shelf

AbstractThe observation station “Melax” was deployed in 2015 on the wide and shallow south Senegalese shelf to study the ocean dynamics, air‐sea interactions, and dissolved oxygen (DO) cycle. Data from February 2015 to August 2016 were used to study the main physical processes affecting the variability of DO in the bottom layer (∼30 m depth) on time scales ranging from tidal to seasonal. Between November and May, wind‐driven upwelling provides phytoplankton enrichment of the surface layers and brings cold, salty, and depleted DO on the shelf. Water properties at Melax vary depending on the source waters located at the shelf edge. The DO concentration changes between the shelf edge and Melax are broadly consistent with the inferred respiration rates estimated in previous studies. In contrast, the monsoon season (July–October) is characterized by weak westerly winds and northward currents. Bottom waters are warmer, fresher, and more oxygenated. The slower circulation in this period allows a stronger decoupling between the water properties of the waters observed at Melax and those of the source waters. Stratification strengthening near the bottom layer inhibits vertical mixing and induces strong high‐frequency variability in properties caused by internal tide‐generated waves. Intense upwelling events can deepen the mixed layer and intermittently transform the bottom layer waters (locally or remotely). Relaxation events associated with current reversals significantly modify their properties. Coastal trapped waves constitute a distant forcing that can act year‐round, impacting both shelf waters and source regions.

On-line Measurement of Sub-ppb Level Hydrogen Peroxide in Ultrapure Water Production Process.

An on-line H2O2 analyzer was developed for application to the ultrapure water production process, using a gasometric method. The analyzer consists of a dissolved oxygen (DO) sensor and analyzer, a catalyst that converts H2O2 to O2, and a computer that stores the DO data. H2O2 concentrations were calculated by measuring the change in DO concentration before and after the catalyst and using the calculation formula presented in this study. In order to accurately analyze a sub-ppb level of H2O2, a DO meter which can correctly measure the DO concentration at the ppb level was applied. An ion exchange resin with Pd, was selected as an appropriate catalyst since it could decompose 99% of H2O2 to O2 at a space velocity of 120/h. The minimum analysis time was 20 min, and the detection limit was observed to be 0.27 ppb. When the DO concentration of the sample was 1.5 ppb or lower, an H2O2 concentration of 1 ppb or lower was successfully measured. Good correlation, with an R2 value of 0.99, was observed between the measured and calculated H2O2 concentrations.

Impacts of anthropogenic inputs on hypoxia and oxygen dynamics in the Pearl River estuary

Abstract. In summer, the Pearl River estuary (PRE) experiences hypoxia, largely driven by the high input of fresh water with low dissolved oxygen (DO), abundant nutrients and particulate organic carbon from the Pearl River network. In this study, we used a well-validated physical–biogeochemical model together with a DO species-tracing method to study the responses of hypoxia and oxygen dynamics to the anthropogenic perturbations of riverine inputs (i.e. DO, nutrients, and particulate organic carbon) in July–August 2006. Model results showed that hypoxia in the PRE was most sensitive to riverine inputs of particulate organic carbon, followed by DO concentrations and nutrients. Specifically, a 50 % decrease (increase) in riverine input of particulate organic carbon led to a 47 % decrease (64 % increase) in hypoxic area, with the sediment oxygen demand and water column production being the two most important processes contributing to changes in DO concentration. Changes in the riverine inputs of DO and nutrients had little impact on the simulated hypoxia because of the buffering effects of re-aeration (DO fluxes across the air–sea interface); i.e. the re-aeration responded to the changes in surface apparent oxygen utilization (AOU) associated with river-induced variations of oxygen source and sink processes. The PRE features shallow waters (with averaged depth of 10 m) in which oxygen provided by the re-aeration could penetrate to bottom waters via vertical diffusion and largely offset the changes in DO contributed by other oxygen source and sink processes. This study highlights the importance of re-aeration in reducing hypoxia variability in shallow estuaries.

Impact of dissolved oxygen on the microbial community structure of an intermittent biological aerated filter (IBAF) and the removal efficiency of gasification wastewater

A novel IBAF system (altered conventional biological aerated filter (BAF) for intermittent aeration) was used to treat BDD anodes electrochemical oxidation gasification wastewater effluent, after which 454 pyrosequencing was applied to investigate the bacterial community of IBAF and demonstrate the relationship between dissolved oxygen (DO) and the bacterial community. The results showed that the concentration of COD, NH4+-N and NO3−-N reached 55.08, 7.64 and 7.76 mg/L, respectively, in IBAF effluent because of changes in the DO concentration at 30 days after system start-up. The bacterial community results revealed that the 40 cm sample had the highest bacterial diversity. The bacterial species were approximate in total samples at phylum and family level, but the relative abundance was significantly different because of change in DO concentration. In addition, sample distance analysis indicated that the similarity of different samples was related to the DO concentration at different heights.

Preparation of slow-releasing oxygen materials and study on their properties

Abstract Slow-releasing oxygen materials were prepared to overcome some limitations regarding the low dissolved oxygen (DO) concentration and the low efficiency of in-situ purification in groundwater. Tests on slow-releasing oxygen materials that could be used to change the reductive environment in groundwater by slowly releasing oxygen were carried out. Oxygen-releasing laboratory experiments were conducted to monitor changes in DO concentration, pH, and total dissolved solids (TDS) in aqueous solutions. The adsorption of the materials on total Fe and Mn were also analyzed. The experimental results showed that the oxygen-releasing status of materials was stable at 15 mg/L after 20 d for fixed-shape materials. Paraffin wax shells and a KH2PO4 pH regulator facilitated the lowering of pH. The oxygen-releasing process followed the quasi-second-order kinetic model, and the oxygen-releasing rate constant K was 1.28, 1.51, and 1.97 (mg/(L·h)) for silt, silty sand, and fine sand medium, respectively. The larger the seepage medium particles were, the faster the pH and TDS dropped. Adsorption experiment results showed that adsorption on total Fe and Mn were well simulated by the Langmuir nonlinear isothermal adsorption equation. The maximum adsorption capacities of the materials on total Fe and Mn were found to be 0.708 mg/g and 0.438 mg/g, respectively.

Predicting the degree of surface oxidation on fine coals by measuring the oxygen transfer rate in coal suspensions

Coal surface oxidation plays a dominant role in differential coal flotation and the utilization of coal products. However, a robust and reliable tool to determine coal surface oxidation in coal preparation plants is not currently available. In this study, a novel technique was developed to determine the degree of coal surface oxidation by measuring the adsorption rate of oxygen on coal surfaces after understanding the nature of oxygen transfer in water and oxygen adsorption on oxidized and un-oxidized coal surfaces. In this study, coal samples with different extents of surface oxidation were prepared and the degree of coal surface oxidation was quantified by X-ray photoelectron spectroscopy (XPS) as the percentage of oxidized carbon. Oxygen was purged into the coal suspension at a constant flow rate and the change of dissolved oxygen (DO) concentration was monitored. It was found that the DO concentration increased with oxygen purging time and the rate of increase was dependent on the degree of coal surface oxidation. A faster increase in DO concentration was observed for more oxidized coals, which is related to a slower adsorption of oxygen on oxidized coal surfaces and, therefore, more dissolved oxygen remained in the suspension. The kinetics of the change of DO concentration was calculated using the oxygen transfer equation, based on which the rate of oxygen adsorption on coal surfaces was obtained. A linear relationship was found between the oxygen adsorption rate and the degree of coal surface oxidation. This technique may be implemented in coal preparation plants as a daily tool to closely monitor the coal oxidation status due to its simplicity and accuracy.

Decolorization of dark brown colored coffee effluent using zinc oxide particles: The role of dissolved oxygen in degradation of colored compounds

The degradation of model dark brown colored coffee effluent using photocatalyst zinc oxide (ZnO) has been systematically studied by varying ZnO dosage from 0 to 4000 mg L−1, coffee loading from 0 to 90 mg L−1 and intensity of UV light having the radiation peak at 352 nm from 0 to 18 W(m-lamp length)−1. Almost complete decolorization was achieved after 180 min for the initial coffee concentration of 50 mg L−1 with ZnO dosage of 3000 mg L−1 and three UV lamps. The dissolved oxygen (DO) largely affected the photodecolorization process. Without air sparging or with oxygen supply only through the free-surface, the DO concentration significantly decreased during the initial decolorization process and then increased to the saturated DO concentration after about 80% decolorization was achieved. Under the anoxic condition with nitrogen gas sparging, the efficient color removal was not obtained unlike the decolorization without air sparging or under the oxic condition with air sparging. These findings suggest that the change in DO concentration was controlled by the oxygen consumption for the formation of oxygen adduct intermediates such as organoperoxy radicals. The mineralization rate of model coffee effluent was rather slow as compared with the decolorization rate and it was insignificantly affected by anoxic and oxic conditions. The present results indicate that ZnO photocatalyst has potential for treatment of coffee processing wastewaters.

New methods for estimating components of lake metabolism based on free-water dissolved-oxygen dynamics

Exchange of carbon between the biosphere and atmosphere is dominated by rates of photosynthetic CO2 uptake and respiratory CO2 release by aquatic and terrestrial ecosystems worldwide. Obtaining accurate estimates of these rates is therefore important. In lakes, the most common estimation method is based on a model of dissolved-oxygen (DO) dynamics and a corresponding time series of DO concentrations measured in freely moving lake water. O2 production and consumption are inferred from changes in DO concentration, then converted to estimates of carbon uptake and release using photosynthetic and respiratory quotients. The traditional method of this type uses a simple accounting procedure to estimate daily gross primary production (GPP), total respiration (R), and net production (NP). Assuming that measured DO concentrations contain no error, it attempts to back-calculate GPP, R, and NP from an observed time series without using statistical techniques. This method produces valid estimates of GPP and the nighttime component of R, but it is unable to estimate the daytime component of R and hence cannot estimate R or NP for a complete dark–light cycle. To obtain estimates of these quantities, one must subjectively assume a value for daytime respiration. We present three new methods for estimating GPP, R, and NP that resolve this problem and also facilitate assessment of model adequacy. We illustrate use of the methods and compare their parameter estimates by applying them to monitoring data from Muskegon Lake, Michigan (USA).

Seasonal spatial distribution of juvenile lake sturgeon in Muskegon Lake, Michigan, USA

AbstractWe examined seasonal spatial distribution and diel movements of juvenile lake sturgeon Acipenser fulvescens in Muskegon Lake, Michigan (a protected, drowned river mouth lake that links the Muskegon River to Lake Michigan). We surgically implanted ultrasonic tags in 20 juveniles (age 1–7) captured in gill nets to track their locations during August–December 2008/2009 and September 2010–October 2011. Most juveniles were observed ≤1.5 km from the mouth of the Muskegon River in Muskegon Lake at a mean depth of 7.5 m (SE = 1.3 m) during summer. In fall, juveniles moved away from the river mouth to the deepest part of Muskegon Lake and were observed at a mean depth of 15.8 m (SE = 1.3 m) during winter. The shift in spatial distribution coincided with fall turnover (i.e., loss of thermal stratification) and with changes in dissolved oxygen (DO) concentrations in the hypolimnion. During summer, DO concentrations in the hypolimnion were typically &lt;4 mg·l−1 in the deepest part of Muskegon Lake and DO concentrations at locations of tagged lake sturgeon were &gt;7 mg·l−1 in 94% of instances. Tracking in 2009 revealed no significant change in depth distribution or movement over the diel cycle. We only observed two tagged juveniles immigrating to Lake Michigan, suggesting that juveniles use Muskegon Lake for multiple years. Our results suggest that: (i) Muskegon Lake serves as an important nursery habitat for juvenile lake sturgeon that hatched in the Muskegon River before they enter Lake Michigan and (ii) seasonal changes in DO concentration in the hypolimnion likely affect the spatial distribution of juveniles in Muskegon Lake.