scholarly journals Water temperature, specific conductance, pH, and dissolved-oxygen concentrations in the lower White River and the Puyallup River estuary, Washington, August-October 2002

2003 ◽  
Keyword(s):  
Dissolved Oxygen ◽  
Water Temperature ◽  
River Estuary ◽  
Specific Conductance ◽  
White River ◽  
Oxygen Concentrations

scholarly journals Artificially oxygenating the Swan River estuary increases dissolved oxygen concentrations in the water and at the sediment interface

2019 ◽  
Vol 128 ◽  
pp. 112-121 ◽  
Author(s):  
Sarah J. Larsen ◽  
Kieryn L. Kilminster ◽  
Alessandra Mantovanelli ◽  
Zoë J. Goss ◽  
Georgina C. Evans ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
River Estuary ◽  
Swan River ◽  
Sediment Interface ◽  
Oxygen Concentrations

Hypoxia-based habitat compression in the Neuse River Estuary: context-dependent shifts in behavioral avoidance thresholds

2002 ◽  
Vol 59 (6) ◽  
pp. 952-965 ◽  
Author(s):  
Lisa A Eby ◽  
Larry B Crowder
Keyword(s):  
Dissolved Oxygen ◽  
Nutrient Loading ◽  
Sublethal Effects ◽  
River Estuary ◽  
Classification And Regression Tree ◽  
Neuse River Estuary ◽  
Estuarine Fish ◽  
Behavioral Avoidance ◽  
Context Dependent ◽  
Oxygen Concentrations

Anthropogenic activities in estuarine watersheds alter physical and chemical characteristics of these ecosystems. Increased nutrient loading and changes in hydrology affect oxygen budgets and subsequently alter the spatial and temporal extent of hypoxia. We used classification and regression tree analyses to examine behavioral avoidance thresholds over a range of dissolved oxygen concentrations. In an examination of 10 fish species, all avoided areas with dissolved oxygen concentrations of <2.0 mg·L–1. Our data suggest that the dissolved oxygen avoidance threshold expressed by fish may be context-dependent. Specifically, the spatial extent of hypoxia significantly affected avoidance thresholds. Fish may occupy poorer quality habitat (areas with lower dissolved oxygen levels) as conditions worsen and the size of the oxygenated refuge shrinks. When the entire estuary is oxygenated, fish utilize all depths. During hypoxic episodes, fish are restricted to oxygenated, shallow, warmer areas. This habitat compression may result in higher densities and greater overlap with potential competitors and predators. Hypoxic zones alter habitat use and may increase bioenergetic costs, potentially resulting in sublethal effects, i.e., decreased growth and condition, on the estuarine fish community.

scholarly journals Unusual vertical distribution of zooplankton and fish in the pelagic zone of Lake Sevan during summer stratification

2021 ◽  
Vol 4 (3) ◽  
pp. 27-41
Author(s):  
Mikhail I. Malin ◽  
Svetlana M. Zhdanova ◽  
Dmitriy B. Kosolapov ◽  
Inga P. Malina ◽  
Natalya G. Kosolapova ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Vertical Distribution ◽  
Water Temperature ◽  
Lower Boundary ◽  
Fish Population ◽  
Coregonus Lavaretus ◽  
Zooplankton Abundance ◽  
Night Time ◽  
Lake Sevan ◽  
Oxygen Concentrations

Previous studies in Lake Sevan during summer stratification have shown that the highest zooplankton abundance and biomass was found at the lower boundary of the epilimnion. At the same time, whitefish (Coregonus lavaretus), being main planktivorous species in the lake, preferred the hypolimnion, but was leaving this layer if dissolved oxygen concentrations decreased to 1–5 mg/L. The study was conducted in Bolshoy Sevan (the southern part of Lake Sevan) on July 29–30, 2019. The vertical profiles of water temperature and dissolved oxygen concentration, as well as distribution of major taxonomic groups of aquatic organisms were assessed four times a day: in the dark (night time), in the light (day time), and in twilight (morning and evening). Fish population density was assessed using a “Simrad EK80” echosounder. Vertical distribution of zooplankton and fish observed within the study period did not correspond to that described earlier. Maximal zooplankton biomass during the study was recorded in the hypolimnion, and minimal biomass, in the epilimnion. Most of fish (89–100%) located in the metalimnion. At night, about 10% of the fish population descended to the hypolimnion, despite the low dissolved oxygen concentrations found there (3.0–3.1 mg/L). At dawn, about 7% of the fish ascended to the epilimnion, reaching a 7-m depth, where the water temperature was 20.8 °C. The water temperature range preferred by most fish individuals varied during the observation period and did not correspond to previously reported ranges.

Analysis and numerical simulation of natural and human-caused low dissolved oxygen in the Minjiang River Estuary

2016 ◽  
Vol 73 (10) ◽  
pp. 2475-2485 ◽  
Author(s):  
Peng Zhang ◽  
Yong Pang ◽  
Chengchun Shi ◽  
Yishu Wang ◽  
Lei Xu ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Dissolved Oxygen ◽  
Water Temperature ◽  
River Discharge ◽  
Flood Control ◽  
Nutrient Loading ◽  
River Estuary ◽  
Water Age ◽  
Drought Period ◽  
Minjiang River

The Minjiang River, a typical tidal channel in Southeast China, plays an important role in the supply of drinking water, flood control and drought relief, farming and navigation, as well as shipping and other functions. Dissolved oxygen (DO), as a basic living condition for aquatic biota, has been deteriorating in the Minjiang River in recent years. In order to understand how the spatial distribution of DO responds to river discharge, nutrient loading and water temperature, a three-dimensional Environmental Fluid Dynamics Code model was used to simulate water age and the distribution of DO in the Minjiang River. The model presented in this paper was used for water resource and water quality simulations under various physical, chemical, and biological scenarios. Sensitivity simulation results indicated that the three factors had a significant impact on the spatial distribution variation of DO in the Minjiang River. Increased river discharge or split ratio of the North Channel resulted in decreased water age and increased DO. Increased nutrient loading and water temperature caused lower DO. In order to protect coastal environments in the Minjiang River, river discharge should be increased and pollutants of local cities should be reduced during the high temperature and drought period.

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