scholarly journals Global warming projection of the change in dissolved oxygen concentrations in low oxygen regions of the oceans

2006 ◽  
Vol 70 ◽  
Author(s):  
Richard Matear
Keyword(s):  
Global Warming ◽  
Dissolved Oxygen ◽  
Low Oxygen ◽  
Global Warming Projection ◽  
Oxygen Concentrations

Tolerance to low dissolved oxygen by the tubicolous polychaete Loimia medusa

1994 ◽  
Vol 74 (1) ◽  
pp. 143-148 ◽  
Author(s):  
Roberto J. Llanso ◽  
Robert J. Diaz
Keyword(s):  
Dissolved Oxygen ◽  
Common Species ◽  
Severe Hypoxia ◽  
Sediment Surface ◽  
Low Oxygen ◽  
Low Dissolved Oxygen ◽  
Oxygen Concentrations

Tolerance and behaviour to hypoxia and anoxia by the annelid Loimia medusa (Savigny) (Polychaeta: Terebellidae), a common species in estuarine habitats where summer hypoxic events often occur, were examined in the laboratory. The worm can tolerate anoxia or severe hypoxia (7% air saturation at 26°C) for 3 to 5 d. Under low dissolved oxygen (<14% air saturation) feeding stops, although tube irrigation continues and periodic protrusions from the tube are common. Most worms come out to the sediment surface, but the number of worms dead on the surface is higher in anoxia than in hypoxia. The prevalence of L. medusa in deep estuarine channels may be partially explained by its tolerance to prolonged periods of hypoxia (14 d at 14% air saturation). Our data, however, suggest that subtle changes in oxygen concentrations may be important in the control of populations of L. medusa in habitats affected by low oxygen disturbances.

scholarly journals Constraining oxygen consumption by nitrite oxidation in oceanic oxygen minimum zones

2020 ◽  
Author(s):  
J.M. Beman ◽  
S.M. Vargas ◽  
J.M. Wilson ◽  
E. Perez-Coronel ◽  
S. Vazquez ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Dissolved Oxygen ◽  
North Pacific Ocean ◽  
Low Oxygen ◽  
Nitrite Oxidation ◽  
Oxygen Minimum Zones ◽  
Oxidation Rates ◽  
Low Levels ◽  
Oxygen Minimum ◽  
Oxygen Concentrations

AbstractOceanic oxygen minimum zones (OMZs) occur where microorganisms deplete dissolved oxygen (DO) to exceptionally low levels, and are globally significant sites of biogeochemical cycling. Amid the intense competition for DO and other substrates occurring in these metabolically challenging environments, aerobic nitrite oxidation may consume significant amounts of DO, but this has not been examined comprehensively. Using parallel measurements of oxygen consumption rates and 15N-nitrite oxidation rates applied to water column profiles and to oxygen manipulation experiments, we show that nitrite oxidation is a substantial sink for DO in the ocean’s largest OMZ. The contribution of nitrite oxidation to overall DO consumption increased at low DO concentrations, tracking gradients and variations within and across multiple stations in the eastern tropical North Pacific Ocean. Oxygen manipulation experiments produced highly consistent effects, with nitrite oxidation responsible for progressively more DO consumption (up to 97%) as DO was experimentally decreased. Natural abundance stable isotope data indicated coupling of nitrite oxidation and nitrate reduction, while 16S rRNA and metagenome sequencing revealed that Nitrospina ecotypes possessing high-affinity cytochrome oxidase genes were prevalent and active within the OMZ. Collectively, our results demonstrate that nitrite oxidation consumes significant amounts of DO, and that this proportion increases as DO declines—indicating that nitrite oxidation is critically important to the formation and maintenance of OMZs.SignificanceOceanic oxygen minimum zones (OMZs) are naturally-occuring regions of low oxygen found in select areas of the ocean. Lack of dissolved oxygen has important implications for both the distribution of marine organisms and global biogeochemical cycles, yet we have a limited understanding of how oxygen is depleted to such low levels. Here we comprehensively quantify the contribution of nitrite oxidation to oxygen depletion in the ocean’s largest OMZ. We observed highly consistent patterns across depth profiles, and in multiple experiments where we manipulated oxygen concentrations, finding that nitrite oxidation consumes progressively more oxygen at lower oxygen concentrations. Our findings demonstrate that nitrite oxidation plays a pivotal role in exhausting oxygen to the low levels found in OMZs.

scholarly journals Testate amoebae (Amoebozoa: Arcellinidae) as indicators of dissolved oxygen concentration and water depth in lakes of the Lacandón Forest, southern Mexico

2019 ◽  
Vol 79 (1) ◽  
Author(s):  
Norma Fernanda Charqueño Celis ◽  
Martin Garibay ◽  
Itzel Sigala ◽  
Mark Brenner ◽  
Paula Echeverria-Galindo ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Water Depth ◽  
Diversity Index ◽  
Testate Amoebae ◽  
Sediment Surface ◽  
Ambient Conditions ◽  
Low Oxygen ◽  
Southern Mexico ◽  
Oxygen Concentrations

The ecology of aquatic protists such as testate amoebae is poorly known worldwide, but is almost completely unknown in lakes of the northern Neotropics. To address this knowledge gap, we analyzed testate amoebae (Amoebozoa: Arcellinidae) in lakes of the Lacandón Forest, one of the most biodiverse parts of southern México. We set out to evaluate the diversity of testate amoebae communities and assess whether testate amoebae taxa are reliable indicators of environmental variables dissolved oxygen and water depth. We collected 17 surface sediment samples from a range of water depths in six lakes across the Naha-Metzabok Biosphere Reserve, northeastern Chiapas state. We identified 15 testate amoebae taxa distributed across seven genera. Eleven were identified to species level and four to strain (infra-subspecific level), and taxa were distributed unevenly among samples. Distribution of taxa in samples was related to dissolved oxygen (DO) concentration in the water measured near the sediment surface. Arcella discoides and Centropyxis aculeata strain “aculeata” were the most tolerant of low oxygen concentrations, whereas the other taxa require higher DO levels. The influence of oxygen was also seen at the assemblage level. Sites with low DO concentrations had Shannon Diversity Index (SDI) values <1.5, an indication of stressful ambient conditions. We identified two species assemblage types, which are distinguished by their oxygen concentration requirements. Assemblage 1 was more diverse and possessed species that are intolerant of low oxygen concentrations, whereas Assemblage 2 possessed fewer, rarer, opportunistic species that tolerate stressful conditions. Low oxygen concentrations are related to water depth and the combination of these two variables is important in determining the composition of testate amoebae assemblages in Lacandón Forest lakes. Quantitative relationships between testate amoebae assemblages and water depth will enable use of sedimented amoebae remains for paleolimnological inference of past water level changes in lakes of the Lacandón Forest.

Effect of Dissolved Oxygen Concentrations on the Toxicity of Several Poisons to Rainbow Trout (Salmo Gairdnerii Richardson)

1961 ◽  
Vol 38 (2) ◽  
pp. 447-455
Author(s):  
R. LLOYD
Keyword(s):  
Rainbow Trout ◽  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Ph Value ◽  
Dissolved Oxygen Concentration ◽  
Low Oxygen ◽  
Copper Salts ◽  
Respiratory Flow ◽  
The Difference ◽  
Oxygen Concentrations

1. A given reduction in the dissolved oxygen concentration of the water from the air-saturation value to a lower level increases the toxicity to rainbow trout of zinc, lead and copper salts, and of a mixture of monohydric phenols, to about the same extent. 2. The effect of a reduced oxygen concentration on the toxicity of ammonia solutions is greater than that found for the other four poisons; the extra increase can be accounted for by a theoretical calculation of the difference between the pH value of the bulk of the solution and that at the gill surface. 3. An hypothesis is presented to account for the effect of low oxygen concentrations on the toxicity of poisons to fish. It assumes that a given toxic effect is produced by a specified concentration of poison at the gill surface, and suggests that this concentration is governed not only by the concentration of poison in the bulk of the solution but also by the velocity of respiratory flow.

A New Life for the St. Croix River

1988 ◽  
Vol 23 (4) ◽  
pp. 568-577
Author(s):  
Harold S. Bailey
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Discharge Rate ◽  
Paper Mill ◽  
Regulated River ◽  
Secondary Treatment ◽  
Pulp And Paper Mill ◽  
Oxygen Regime ◽  
Oxygen Concentrations

Abstract The water quality of the upper 110 kilometres of the St. Croix River is considered to be pristine. A major industrial discharge renders the lower 14 kilometres of the river a water quality limited segment. Prior to 1970 the Georgia-Pacific Pulp and Paper Mill at Woodland, Maine, discharged untreated effluent directly into the river causing dissolved oxygen concentrations to drop well below 5 mg/L, the objective chosen in the interest of restoring endemic fish populations. Since 1972, the Mill has installed primary and secondary treatment, regulated river discharge rate and effluent composition which has greatly improved the summer dissolved oxygen regime. By 1980, dissolved oxygen concentrations were generally above 5.0 mg/L and restocking the river with Atlantic Salmon (Salmo salar) was initiated.

Enhanced human lysozyme production by Pichia pastoris via periodic glycerol and dissolved oxygen concentrations control

2021 ◽  
Vol 105 (3) ◽  
pp. 1041-1050
Author(s):  
Luqiang Jia ◽  
Teng Li ◽  
Yixuan Wu ◽  
Chunsen Wu ◽  
Huaxiang Li ◽  
...  
Keyword(s):  
Pichia Pastoris ◽  
Dissolved Oxygen ◽  
Human Lysozyme ◽  
Oxygen Concentrations

Hypoxic tolerance of Chinese black sleeper Bostrichthys sinensis embryos at heartbeat stage

2006 ◽  
Vol 86 (6) ◽  
pp. 1473-1476 ◽  
Author(s):  
Shixi Chen ◽  
Wanshu Hong ◽  
Wei Zhou ◽  
Qiyong Zhang
Keyword(s):  
Dissolved Oxygen ◽  
Exposure Time ◽  
Hypoxic Conditions ◽  
Hypoxic Tolerance ◽  
Heartbeat Rate ◽  
Bostrichthys Sinensis ◽  
Oxygen Concentrations

Tolerance of hypoxia in Chinese black sleeper (Bostrichthys sinensis) embryos at heartbeat stage was examined at different oxygen concentrations. Embryonic response to hypoxic conditions was expressed in terms of the intensity of variation in heartbeat rate (V). Exposure of the embryos at 25°C to 0.5, 1.0 and 1.5 mg/l dissolved oxygen (DO), caused bradycardia, which was developed within the first 10 min of hypoxia, followed by a plateau, and lasted until termination of the hypoxia. The V values were significantly affected by DO concentrations (P<0.01). Exposure of the embryos to 0.2 mg/l DO at 25°C caused a periodic heartbeat (including a period of heartbeat and a period of silence). This phenomenon was first recorded in the present study. During the period of heartbeat, the heartbeat rates were faster at first (147±5 beats per min), and then decreased gradually until the period of silence. As the exposure time increased, the duration of heartbeat was prolonged significantly from 43.4±2.4 second to 126.2±8.2 second (P<0.01), and the duration of silence was also prolonged significantly from 68.0±5.5 second to 247.9±11.5 second (P<0.01). At the beginning of exposure, the primary heartbeat rates displayed tachycardia, and their V values were significantly lower than the V values of average heartbeat rates (P<0.05). However, the V values were not significantly different between primary heartbeat rate and average heartbeat rate after 90 min exposure (P>0.05).

Sign in / Sign up

Export Citation Format

Share Document