scholarly journals Red Tide Events and Seasonal Variations in the Partial Pressure of CO2 and Related Parameters in Shellfish-Farming Bays, Southeastern Coast of Korea

2021 ◽  
Vol 8 ◽  
Author(s):  
JeongHee Shim ◽  
Mi-Ju Ye ◽  
Jae-Hyun Lim ◽  
Jung-No Kwon ◽  
Jeong Bae Kim
Keyword(s):  
Carbon Cycle ◽  
Partial Pressure ◽  
Bottom Water ◽  
Red Tide ◽  
Seawater Temperature ◽  
Spatiotemporal Variability ◽  
Red Tides ◽  
Surface Seawater ◽  
Biological Production ◽  
The Mean

Mixed results have been reported on the evaluation of the coastal carbon cycle and its contribution to the global carbon cycle, mainly due to the shortage of observational data and the considerable spatiotemporal variability arising from complex biogeochemical factors. In this study, the partial pressure of carbon dioxide (pCO2) and related environmental factors were measured in the Jinhae–Geoje–Tongyeong bay region of the southeastern Korean Peninsula in February 2014, August 2014, April 2015, and October 2015. The mean pCO2 of surface seawater ranged from 215 to 471 μatm and exhibited a high correlation with the surface seawater temperature when data for August were excluded (R2 = 0.69), indicating that the seasonal variation in CO2 could be largely attributed to the variation in seawater temperature. However, a severe red tide event occurred in August 2014, when the lowest pCO2 value was observed despite a relatively high seawater temperature. It is considered that the active biological production of phytoplankton related to red tides counteracted the summer increase in pCO2. Based on the correlation between pCO2 and temperature, the estimated decrease in pCO2 caused by non-thermal factors was approximately 200 μatm. During the entire study period, the air–sea CO2 flux ranged from −14.2 to 3.7 mmol m–2 d–1, indicating that the study area served as an overall sink for atmospheric CO2, and only functioned as a weak source during October. The mean annual CO2 flux estimated from the correlation with temperature was −5.1 mmol m–2 d–1. However, because this estimate did not include reductions caused by sporadic events of biological production, such as red tides and phytoplankton blooms, the actual uptake flux is considered to be higher. The mean saturation state (ΩAr) value of carbonate aragonite was 2.61 for surface water and 2.04 for bottom water. However, the mean ΩAr of bottom water was <2 in August and October, and the ΩAr values measured at some of the bottom water stations in August were <1. Considering that the period from August to October corresponds to the reproduction and growth stages of shellfish, such low ΩAr values could be very damaging to shellfish production and the aquaculture industry.

scholarly journals Feeding diverse prey as an excellent strategy of mixotrophic dinoflagellates for global dominance

2021 ◽  
Vol 7 (2) ◽  
pp. eabe4214
Author(s):  
Hae Jin Jeong ◽  
Hee Chang Kang ◽  
An Suk Lim ◽  
Se Hyeon Jang ◽  
Kitack Lee ◽  
...  
Keyword(s):  
Genetic Factor ◽  
Red Tide ◽  
Biogeochemical Cycles ◽  
Evolutionary Strategy ◽  
Distribution Data ◽  
Red Tides ◽  
Trade Off ◽  
Moderate Growth ◽  
Prey Diversity ◽  
Standing Question

Microalgae fuel food webs and biogeochemical cycles of key elements in the ocean. What determines microalgal dominance in the ocean is a long-standing question. Red tide distribution data (spanning 1990 to 2019) show that mixotrophic dinoflagellates, capable of photosynthesis and predation together, were responsible for ~40% of the species forming red tides globally. Counterintuitively, the species with low or moderate growth rates but diverse prey including diatoms caused red tides globally. The ability of these dinoflagellates to trade off growth for prey diversity is another genetic factor critical to formation of red tides across diverse ocean conditions. This finding has profound implications for explaining the global dominance of particular microalgae, their key eco-evolutionary strategy, and prediction of harmful red tide outbreaks.

scholarly journals High Spatial-Resolution Red Tide Detection in the Southern Coast of Korea Using U-Net from PlanetScope Imagery

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4447
Author(s):  
Jisun Shin ◽  
Young-Heon Jo ◽  
Joo-Hyung Ryu ◽  
Boo-Keun Khim ◽  
Soo Mee Kim
Keyword(s):  
Deep Learning ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Red Tide ◽  
Learning Approaches ◽  
Red Tides ◽  
Southern Coast ◽  
Color Sensors ◽  
Deep Learning Model ◽  
Bloom Water

Red tides caused by Margalefidinium polykrikoides occur continuously along the southern coast of Korea, where there are many aquaculture cages, and therefore, prompt monitoring of bloom water is required to prevent considerable damage. Satellite-based ocean-color sensors are widely used for detecting red tide blooms, but their low spatial resolution restricts coastal observations. Contrarily, terrestrial sensors with a high spatial resolution are good candidate sensors, despite the lack of spectral resolution and bands for red tide detection. In this study, we developed a U-Net deep learning model for detecting M. polykrikoides blooms along the southern coast of Korea from PlanetScope imagery with a high spatial resolution of 3 m. The U-Net model was trained with four different datasets that were constructed with randomly or non-randomly chosen patches consisting of different ratios of red tide and non-red tide pixels. The qualitative and quantitative assessments of the conventional red tide index (RTI) and four U-Net models suggest that the U-Net model, which was trained with a dataset of non-randomly chosen patches including non-red tide patches, outperformed RTI in terms of sensitivity, precision, and F-measure level, accounting for an increase of 19.84%, 44.84%, and 28.52%, respectively. The M. polykrikoides map derived from U-Net provides the most reasonable red tide patterns in all water areas. Combining high spatial resolution images and deep learning approaches represents a good solution for the monitoring of red tides over coastal regions.

Estimation of carbon cycle changes in river-estuarine continuum by using advanced earth system model

2021 ◽  
Author(s):  
Tadanobu Nakayama
Keyword(s):  
Carbon Cycle ◽  
Aquatic Ecosystems ◽  
Carbon Budget ◽  
Overland Flow ◽  
Seawater Temperature ◽  
Nutrient Cycle ◽  
Anthropogenic Factors ◽  
Inland Waters ◽  
Global Changes ◽  
Transport Pathway

<p>Inland waters including rivers, lakes, and groundwater are suggested to act as a transport pathway for water and dissolved substances, and play some role in continental biogeochemical cycling (Cole et al., 2007; Battin et al., 2009). Quantifying the physical and chemical connections between land and associated fresh and coastal waters is critical for understanding the dynamics of carbon cycle in aquatic ecosystems. Recently, process-based National Integrated Catchment-based Eco-hydrology (NICE) model (Nakayama and Watanabe, 2004) was developed to couple with various biogeochemical cycle models in biosphere, aquatic ecosystems, and carbon weathering, etc. in global major river basins (NICE-BGC) (Nakayama, 2017; Nakayama and Pelletier, 2018). NICE-BGC also included the feedback between soil organic content and overland carbon fluxes, and succeeded to simulate inter-annual variations of carbon cycle in a terrestrial-aquatic continuum greatly affected by the extreme weather patterns (Nakayama, 2020). To evaluate global changes in the carbon cycle due to anthropogenic factors, such as application of fertilizer and manure, in major rivers including 130 tidal estuaries over an 18-year period (1998-2015), the present study expanded NICE-BGC to estuary in land and ocean margins where it is generally considered to be net heterotrophic ecosystems and show significant supersaturation of CO<sub>2</sub> (Frankignoulle et al., 1998; Regnier et al., 2013). The new model used Dirichlet boundary condition at the downstream of global major rivers by using some variables (water temperature, salinity, dissolved oxygen, nutrient, alkalinity, and pH, etc.) in coastal ocean. The simulated result showed that total nitrogen and phosphorus fluxes in overland flow were found to increase with nutrient application. In contrast, total suspended sediment decreased in some regions because the vegetation was able to expand to cover the ground, resulting in less erosion. NICE-BGC simulated the difference in carbon budget in major rivers with and without nutrient application. Generally, CO<sub>2</sub> degassing above water decreased and particulate organic carbon (POC) increased in most rivers through variations in carbon budget, reflecting various hydrologic and biogeochemical conditions. The simulated result also showed that the estuarine carbon cycle was sensitive to intense anthropogenic disturbances reflected by nutrient load, seawater temperature, increases in sea level, and ocean acidification. Extension of previous studies only by categorizing MARCATS segment numbers showed that the estimated total CO<sub>2</sub> flux from the world’s estuaries was 0.14 Pg C/yr. The simulation generally showed that incorporation of the nutrient cycle into the terrestrial-aquatic-estuarine continuum improved estimates of net land flux and carbon budget in inland waters, thus emphasizing that the effect of estuarine inland water should be explicitly included in the global carbon model to minimize the range of uncertainty.</p>

A Red Tide of Gyrod Inium Aurelum in Sea Lochs of the Firth of Clyde and Associated Mortality of Pond-Reared Salmon

1982 ◽  
Vol 62 (4) ◽  
pp. 771-782 ◽  
Author(s):  
K. J. Jones ◽  
P. Ayres ◽  
A. M. Bullock ◽  
R. J. Roberts ◽  
P. Tett
Keyword(s):  
Osmotic Shock ◽  
Red Tide ◽  
Clinical Signs ◽  
Cellular Damage ◽  
Fish Ponds ◽  
Red Tides ◽  
Gymnodinium Breve ◽  
The North ◽  
Cell Densities ◽  
Gyrodinium Aureolum

Red tides of the naked dinoflagellate Gyrodinium aureolum Hulburt occurred in sealochs in the north of the Firth of Clyde, Scotland, during late September 1980. Greatestconcentrations of the organism were found in the top 1 m layer of the water column, which was stabilized, and probably also enriched with nutrients, by freshwater input fromland drainage. In addition vertical and horizontal concentration must be postulated toexplain Gyrodinium cell densities of 2 x to7 cells I"1 and chlorophyll concentrations of 2228 mg m“”3 near the shore at Otter Ferry, Loch Fyne.On 28 September 1980, water containing the red tide at Otter Ferry was unintentionally pumped into fish ponds at a shore-based salmon farm and resulted in the death, in one pond, of 3000 salmon each weighing about 1 kg and of 200–300 smolts in another when water was transferred to it from the affected pond. Pathological investigation of affected salmon showed that death was likely to have resulted from asphyxiation and osmotic shock as a result of extensive cellular damage to gills and guts. Results of mouse bioassays, using acidic and ether extracts of flesh and guts from affected salmon, suggest that necrotizing toxin(s) was associated with the cells of Gyrodinium aureolum during the bloom. The clinical signs exhibited by mice injected with toxin extracts were, however, unlike those caused by paralytic shellfish poison or toxins of the Gymnodinium breve type.

scholarly journals Micronutrients in support to the one carbon cycle for the modulation of blood fasting homocysteine in PCOS women

2019 ◽  
Vol 43 (6) ◽  
pp. 779-786 ◽  
Author(s):  
N. Schiuma ◽  
A. Costantino ◽  
T. Bartolotti ◽  
M. Dattilo ◽  
V. Bini ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Normal Limit ◽  
Control Group ◽  
Pharmacological Treatments ◽  
Open Label ◽  
Parallel Group ◽  
Alternative Approach ◽  
The Mean ◽  
The One

Abstract Purpose Fasting blood homocysteine is increased in PCOS women and is involved in several of its co-morbidities including cardiovascular disease and infertility. Corrective interventions based on the administration of supra-physiologic doses of folic acid work to a low extent. We aimed to test an alternative approach. Methods This was a prospective, randomized, parallel group, open label, controlled versus no treatment clinical study. PCOS women aged > 18, free from systemic diseases and from pharmacological treatments were randomized with a 2:1 ratio for treatment with activated micronutrients in support to the carbon cycle (Impryl, Parthenogen, Switzerland—n = 22) or no treatment (n = 10) and followed-up for 3 months. Fasting blood homocysteine, AMH, testosterone, SHBGs, and the resulting FTI were tested before and at the end of the follow-up. Results The mean baseline fasting blood homocysteine was above the normal limit of 12 μMol/L and inversely correlated with SHBG. AMH was also increased, whereas testosterone, SHBG, and FTI were within the normal limit. The treatment achieved a significant reduction of homocysteine, that did not change in the control group, independently of the starting value. The treatment also caused an increase of AMH and a decrease of SHBGs only in the subgroup with a normal homocysteine at baseline. Conclusions In PCOS ladies, blood homocysteine is increased and inversely correlated with the SHBGs. Physiologic amounts of activated micronutrients in support to the carbon cycle achieve a reduction virtually in all exposed patients. Whether this is of clinical benefit remains to be established.

scholarly journals On the skill of raw and post-processed ensemble seasonal meteorological forecasts in Denmark

2018 ◽  
Vol 22 (12) ◽  
pp. 6591-6609 ◽  
Author(s):  
Diana Lucatero ◽  
Henrik Madsen ◽  
Jens C. Refsgaard ◽  
Jacob Kidmose ◽  
Karsten H. Jensen
Keyword(s):  
Lead Time ◽  
Spatiotemporal Variability ◽  
Positive Bias ◽  
Seasonal Forecasts ◽  
Weather Forecasts ◽  
Relevant Variables ◽  
Delta Change ◽  
The Mean ◽  
Statistical Consistency

Abstract. This study analyzes the quality of the raw and post-processed seasonal forecasts of the European Centre for Medium-Range Weather Forecasts (ECMWF) System 4. The focus is given to Denmark, located in a region where seasonal forecasting is of special difficulty. The extent to which there are improvements after post-processing is investigated. We make use of two techniques, namely linear scaling or delta change (LS) and quantile mapping (QM), to daily bias correct seasonal ensemble predictions of hydrologically relevant variables such as precipitation, temperature and reference evapotranspiration (ET0). Qualities of importance in this study are the reduction of bias and the improvement in accuracy and sharpness over ensemble climatology. Statistical consistency and its improvement is also examined. Raw forecasts exhibit biases in the mean that have a spatiotemporal variability more pronounced for precipitation and temperature. This variability is more stable for ET0 with a consistent positive bias. Accuracy is higher than ensemble climatology for some months at the first month lead time only and, in general, ECMWF System 4 forecasts tend to be sharper. ET0 also exhibits an underdispersion issue, i.e., forecasts are narrower than their true uncertainty level. After correction, reductions in the mean are seen. This, however, is not enough to ensure an overall higher level of skill in terms of accuracy, although modest improvements are seen for temperature and ET0, mainly at the first month lead time. QM is better suited to improve statistical consistency of forecasts that exhibit dispersion issues, i.e., when forecasts are consistently overconfident. Furthermore, it also enhances the accuracy of the monthly number of dry days to a higher extent than LS. Caution is advised when applying a multiplicative factor to bias correct variables such as precipitation. It may overestimate the ability that LS has in improving sharpness when a positive bias in the mean exists.

scholarly journals Tracing the sources of nutrients fueling dinoflagellate red tides occurring along the coast of Korea using radium isotopes

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hyeong Kyu Kwon ◽  
Guebuem Kim ◽  
Yongjin Han ◽  
Junhyeong Seo ◽  
Weol Ae Lim ◽  
...  
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Red Tide ◽  
Subsurface Layer ◽  
Vertical Mixing ◽  
Eastern Coast ◽  
Nutrient Concentrations ◽  
Red Tides ◽  
Radium Isotopes ◽  
Nutrient Sources

Abstract It is a well held concept that the magnitude of red-tide occurrence is dependent on the amount of nutrient supply if the conditions are same for temperature, salinity, light, interspecific competition, etc. However, nutrient sources fueling dinoflagellate red-tides are difficult to identify since red tides usually occur under very low inorganic-nutrient conditions. In this study, we used short-lived Ra isotopes (223Ra and 224Ra) to trace the nutrient sources fueling initiation and spread of Cochlodinium polykrikoides blooms along the coast of Korea during the summers of 2014, 2016, and 2017. Horizontal and vertical distributions of nutrient concentrations correlated well with 224Ra activities in nutrient-source waters. The offshore red-tide areas showed high 224Ra activities and low-inorganic and high-organic nutrient concentrations, which are favorable for blooming C. polykrikoides in competition with diatoms. Based on Ra isotopes, the nutrients fueling red-tide initiation (southern coast of Korea) are found to be transported horizontally from inner-shore waters. However, the nutrients in the spread region (eastern coast of Korea), approximately 200 km from the initiation region, are supplied continuously from the subsurface layer by vertical mixing or upwelling. Our study highlights that short-lived Ra isotopes are excellent tracers of nutrients fueling harmful algal blooms in coastal waters.

Divergent Eddy Heat Fluxes in the Kuroshio Extension at 144°–148°E. Part II: Spatiotemporal Variability

2013 ◽  
Vol 43 (11) ◽  
pp. 2416-2431 ◽  
Author(s):  
Stuart P. Bishop
Keyword(s):  
Spatial Structure ◽  
Regime Shift ◽  
Kuroshio Extension ◽  
Spatiotemporal Variability ◽  
Unstable State ◽  
Unstable Regime ◽  
Stable Regime ◽  
Eddy Heat Flux ◽  
The Mean ◽  
The Kuroshio

Abstract The Kuroshio Extension System Study (KESS) provided 16 months of observations to quantify divergent eddy heat flux (DEHF) from a mesoscale-resolving array of current- and pressure-equipped inverted echo sounders. KESS observations captured a regime shift from a stable to unstable state. There is a distinct difference in the spatial structure of DEHFs between the two regimes. The stable regime had weak downgradient DEHFs. The unstable regime exhibited asymmetry along the mean path with strong downgradient DEHFs upstream of a mean trough at ~147°E. The spatial structure of DEHFs resulted from episodic mesoscale processes. The first 6 months were during the stable regime in which fluxes were associated with eastward-propagating 10–15-day upper meanders. After 6 months, the Kuroshio Extension underwent a regime shift from a stable to unstable state. This regime shift corresponded with a red shift in mesoscale phenomena with the prevalence of ~40-day deep externally generated eddies. DEHF amplitudes more than quadrupled during the unstable regime. Cold-core ring (CCR) formation, CCR–jet interaction, and coupling between ~40-day deep eddies were responsible for asymmetry in downgradient fluxes in the mean maps not observed during the stable regime. The Kuroshio Extension has prominent deep energy associated with externally generated eddies that interact with the jet to drive some of the biggest DEHF events. These eddies play an important role in the variability of the jet through eddy–mean flow interactions. The DEHFs that result from vertical coupling act in accordance with baroclinic instability. The interaction is not growth from an infinitesimal perturbation, but from the start is a finite-amplitude interaction.

scholarly journals Emulating coupled atmosphere-ocean and carbon cycle models with a simpler model, MAGICC6 – Part 1: Model description and calibration

2011 ◽  
Vol 11 (4) ◽  
pp. 1417-1456 ◽  
Author(s):  
M. Meinshausen ◽  
S. C. B. Raper ◽  
T. M. L. Wigley
Keyword(s):  
Carbon Cycle ◽  
General Circulation ◽  
Climate Model ◽  
General Circulation Models ◽  
Climate System ◽  
Model Description ◽  
Ocean Heat Uptake ◽  
The Mean ◽  
Sres Scenarios ◽  
Ipcc Sres

Abstract. Current scientific knowledge on the future response of the climate system to human-induced perturbations is comprehensively captured by various model intercomparison efforts. In the preparation of the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC), intercomparisons were organized for atmosphere-ocean general circulation models (AOGCMs) and carbon cycle models, named "CMIP3" and "C4MIP", respectively. Despite their tremendous value for the scientific community and policy makers alike, there are some difficulties in interpreting the results. For example, radiative forcings were not standardized across the various AOGCM integrations and carbon cycle runs, and, in some models, key forcings were omitted. Furthermore, the AOGCM analysis of plausible emissions pathways was restricted to only three SRES scenarios. This study attempts to address these issues. We present an updated version of MAGICC, the simple carbon cycle-climate model used in past IPCC Assessment Reports with enhanced representation of time-varying climate sensitivities, carbon cycle feedbacks, aerosol forcings and ocean heat uptake characteristics. This new version, MAGICC6, is successfully calibrated against the higher complexity AOGCMs and carbon cycle models. Parameterizations of MAGICC6 are provided. The mean of the emulations presented here using MAGICC6 deviates from the mean AOGCM responses by only 2.2% on average for the SRES scenarios. This enhanced emulation skill in comparison to previous calibrations is primarily due to: making a "like-with-like comparison" using AOGCM-specific subsets of forcings; employing a new calibration procedure; as well as the fact that the updated simple climate model can now successfully emulate some of the climate-state dependent effective climate sensitivities of AOGCMs. The diagnosed effective climate sensitivity at the time of CO2 doubling for the AOGCMs is on average 2.88 °C, about 0.33 °C cooler than the mean of the reported slab ocean climate sensitivities. In the companion paper (Part 2) of this study, we examine the combined climate system and carbon cycle emulations for the complete range of IPCC SRES emissions scenarios and the new RCP pathways.

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