VALIDATION OF COCHLODINIUM POLYKRIKOIDES RED TIDE DETECTION USING SEAWIFS-DERIVED CHLOROPHYLL-A DATA WITH NFRDI RED TIDE MAP IN SOUTH EAST KOREAN WATERS

Annual summer red tides of Cochlodinium polykrikoides have happenned at southern coastal  of the South Korea, accounted economic losses of 76.4 billion won in 1995 on fisheries and other economic substantial losses. Therefore, it is important to eliminate the damage and losses by monitoring the bloom and to forecast their development and movement. On previous study, ocean color satellite, SeaWiFS, standard chlorophyll-a data was used to detect the red tide, using threshold value of chlorophyll-a concentration ≥ 5 mg/m3, resulted a good correlation using visual comparison. However, statistic based accuracy analysis has not be done yet. In this study, the accuracy of detection method was analyzed using spatial statistic. Spatial statistical match up analysis resulted 68% of red tide area was not presented in satellite data due to masking. Within red tide area where data existed, 36% was in high chlorophyll-a area and 64% was in low chlorophyll-a area. Within the high chlorophyll-a area 13% and 87% was in and out of the red tide area. It was found that the accuracy of this detection is low. However if the accuracy was yearly splitted, its found that 75% accuracy on 2002 where visually red tide detected spead out to the off-shore area. The fail and false detection are not due to the failure of the detection method but caused by limitation of the technology due to the natural condition i.e. type of red tide spreading, cloud cover and other flags such as turbid water, stray light etc

Plankton dynamics on the outer southeastern U.S. continental shelf. Part I: Lagrangian particle tracing experiments

The residence time and flow patterns of plankton populations on the outer southeastern U.S. continental shelf were studied with Lagrangian particle tracing experiments. Flow and temperature fields used for these experiments were constructed by applying optimal interpolation methods to current meter data obtained during the Georgia Bight Experiment I and II which took place 25 February to 18 June 1980 and 10 June to 24 September 1981, respectively. The interpolated fields reproduced the flow and temperature structures associated with Gulf Stream frontal eddies and bottom intrusions, which are the upwelling mechanisms of interest in this region. The general particle tracing results showed that plankton residence time and flow trajectory are controlled primarily by the Gulf Stream location and wind direction. During times when the Gulf Stream is located near the shelf break, plankton are transported rapidly to the north with little onshore flow. Residence times are short, being on the order of three to four days. When the Gulf Stream is located offshore of the shelf break and wind patterns are variable, particle transport shows no preferred direction and residence times on the outer southeastern U.S. shelf are long; sometimes in excess of thirty days. Tracing of particles in waters upwelled in frontal eddies and bottom intrusions showed considerable differences in the fate of plankton associated with these features. Residence times of waters and particles upwelled in frontal eddies are short, four to six days, and transport is northward with the Gulf Stream. Bottom intrusion waters, by contrast, remain on the continental shelf for more than twenty days and transport of these waters and of associated particles is across the shelf to the inshore regions. The particle tracing experiments showed that the different upwelling regimes and changing physical environment greatly affect the transport of material from and across the outer southeastern U.S. continental shelf. This in turn implies that these physical processes are a major component influencing the structure of plankton communities of this region

Primary productivity dynamics in the summer Arctic Ocean confirms broad regulation of the electron requirement for carbon fixation by light-phytoplankton community interaction

© 2019 Zhu, Suggett, Liu, He, Lin, Le, Ishizaka, Goes and Hao. Predicting conversion of photosynthetic electron transport to inorganic carbon uptake rates (the so-called electron requirement for carbon fixation, KC) is central to the broad scale deployment of Fast Repetition Rate fluorometry (FRRf) for primary productivity studies. However, reconciling variability of KC over space and time to produce robust algorithms remains challenging, given the large number of factors that influence KC. We have previously shown that light appears to be a proximal driver of Kc in several ocean regions and we therefore examined whether and how light similarly regulated KC variability in the Arctic Ocean, during a summer cruise in 2016. Sampling transited ice-free and ice-covered waters, with temperature, salinity and Chl-a concentrations all higher for the ice-free than ice covered surface waters. Micro- and pico-phytoplankton generally dominated the ice-free and ice-covered waters, respectively. Values of KC, determined from parallel measures of daily integrated electron transport rates and 14C-uptake, were overall lower for the ice-covered vs. ice-free stations. As in our previous studies, KC was strongly linearly correlated to daily PAR (r = 0.68, n = 46, p < 0.001) and this relationship could be further improved (r = 0.84, n = 46, p < 0.001) by separating samples into ice-free (micro-phytoplankton dominated) vs. ice-covered (Nano- and Pico-phytoplankton dominated water. We subsequently contrasted the PAR-KC relationship form the Arctic waters with the previous relationships from the Ariake Bay and East China Sea and revealed that these various PAR-KC relationships can be systematically explained across regions by phytoplankton community size structures. Specifically, the value of the linear slope describing PAR-KC decreases as water bodies have an increasing fraction of larger phytoplankton. We propose that this synoptic trend reflects how phytoplankton community structure integrates past and immediate environmental histories and hence may be a better broad-scale predictor of KC than specific environmental factors such as temperature and nutrients. We provide a novel algorithm that may enable broad-scale retrieval of CO2 uptake from FRRf with knowledge of light and phytoplankton community size information

Relationships of interannual variability in SST and phytoplankton blooms with giant jellyfish (Nemopilema nomurai) outbreaks in the Yellow Sea and East China Sea

Giant jellyfish (Nemopilema nomurai) outbreaks in relation to satellite sea surface temperature (SST) and chlorophyll-a concentration (Chl-a) were investigated in the Yellow Sea and East China Sea (YECS) from 1998 to 2010. Temperature, eutrophication, and match-mismatch hypothesis were examined to explain long-term increases and recent reductions of N. nomurai outbreaks. We focused on the timing of SST reaching 15oC, a critical temperature enabling polyps to induce strobilation and enabling released ephyra to grow. We analyzed the relationship of the timing with intterannual variability of SST, Chl-a, and the timing of phytoplankton bloom. Different environmental characteristics among pre-jellyfish years (1998-2001), jellyfish year (2002-2007, 2009), and non-jellyfish year (2008, 2010) were assessed on this basis. The SST during late spring and early summer increased significantly from 1985 to 2007. This indicated that high SST is beneficial to the long-term increase in jellyfish outbreaks. SST was significantly lower in non-jellyfish years than in jellyfish years, suggesting that low SST might reduce the proliferation of N. nomurai. We identified three (winter, spring, and summer) major phytoplankton bloom regions and one summer decline region. Both Chl-a during non-blooming period and the peak increased significantly from 1998 to 2010 in most of the YECS. This result indicates that eutrophication is beneficial to the long-term increases in jellyfish outbreaks. Timing of phytoplankton blooms varied interannually and spatially, and their match and mismatch to the timing of SST reaching 15oC did not correspond to long-term increases in N. nomurai outbreaks and the recent absence

Spatial and temporal variations of Biological Production in the Asia-Pacific Marginal Seas

This research project consists several main activities which are considered to be able to improve research capability in the Asia-Pacific region, especially in the collaborating countries. In terms of research, the project focused on discerning spatial and temporal variations of marine biological production in the Asia-Pacific marginal seas (the East China Sea, the South China Sea, the Strait of Malacca, and the Gulf of Thailand) utilizing multisensor satellite observations and coupled hydrodynamic-biogeochemical model. As part of the research achievements, one paper was accepted (in press) for publication in Remote Sensing. Other three or four papers are now under preparation for submission to high impact journals. To achieve research objectives, four (4) young scientists from collaborating countries were also involved in the project, that at once allowing them to improve their research capability and to enter international scientific community. In order to expand international networking and/or research collaboration in the near future, international mini-workshop on the western Pacific Ocean and marginal seas biogeochemical variability was also held in Japan Agency for Marine-Earth Science and Technology (JAMSTEC) in February 2014. As feedback of this research project and research continuation, it has been discussed and planned to propose Japan Society for the Promotion of Science (JSPS) Postdoctoral Fellowships for foreign researchers.Project Reference Number: ARCP2012-21NSY-Siswanto, Final Report submitted to APN ; The original publication is available at APN via http://www.apn-gcr.org/resources/items/show/176

Seasonal and spring interannual variations in satellite-observed chlorophyll-a in the Yellow and East China Seas: New datasets with reduced interference from high concentration of resuspended sediment

Seasonal and spring interannual variations in chlorophyll-a (Chl) and total suspended matter (TSM) in the Yellow and East China Seas through a 10-year period were examined by using new datasets from Yellow Sea Large Marine Ecosystem Ocean Color Project (YOC) algorithms. YOC SCHL calculations are based on a combination of the SeaWiFS standard algorithm and a local empirical algorithm for areas of low and high normalized water leaving radiance 555 nm, respectively. YOC SCHL was lower than the standard SCHL in areas with high concentrations of resuspended sediment, especially along the Chinese and Korean coasts and around the Changjiang Bank from fall to spring. YOC SCHL was high in areas of low TSM in the middle of the Yellow Sea, and off shore of the Changjiang Bank in April, indicating the occurrence of spring blooms. In these areas, TSM was dominated by phytoplankton cells and phytoplankton-related organic particles. Offshore from the Changjiang River mouth and around the Changjiang Bank, YOC SCHL and TSM in March were low and high, respectively, with maximum YOC SCHL values occurring around the Changjiang Bank in May. Spring bloom started with decrease in resuspended sediment concentrations in these areas. During summer, YOC SCHL values were high and TSM concentrations were low; TSM was dominated by organic particles related to phytoplankton activity when Changjiang River diluted water moved from the river mouth to east of the bank. YOC SCHL in spring offshore from the Changjiang River mouth increased significantly during the 10 years, and correspond to an increase in redtide events. In the middle of the Yellow Sea, maximum YOCS CHL in spring increased gradually and significantly during the 10 years. Many of the spatial and temporal variations in YOC SCHL were consistent with a range of earlier in situ descriptions. Our results indicate that the satellite ocean data with proper algorithms is a powerful tool to analyze phytoplankton dynamics in moderate-high suspended sediment area

MODIS-derived green Noctiluca blooms in the upper Gulf of Thailand: Algorithm development and seasonal variation mapping

In recent decades, red tides of non-toxic harmful algal blooms have frequently occurred in monsoon-influenced tropical areas, particularly the green form of Noctiluca scintillans (hereafter green Noctiluca). However, our understanding of the mechanism of red tide formation is hindered by spatial and temporal constraints of field data. In this study, we used moderate resolution imaging spectroradiometer (MODIS) ocean color data along with a locally developed algal-bloom classification algorithm to investigate the seasonal variability of dominant red tides across the upper Gulf of Thailand (uGoT). During our July 2018 observation, a super green Noctiluca bloom with extraordinarily high chl-a (&gt;1,469 mg m-3) displayed a distinct spectral reflectance characteristic among red tides in blue-to-green and red-to-near infrared wavelengths. According to the distinctive in situ hyperspectral characteristics of uGoT algal blooms, we developed a classification algorithm for MODIS normalized at 488, 531, and 667 nm, which successfully discriminated green Noctiluca in three levels of blooms, namely, super (100%), strong (&gt;80%), and weak (&gt;40%), from other algal blooms (i.e., dinoflagellates, diatoms, cyanobacteria, and mixed red tide species) as well as non-bloom oceanic and coastal waters using MODIS data, as confirmed by uGoT red tide reports. Monthly MODIS-based discrimination composites from 2003 to 2021 revealed seasonal variability in the surface distribution and bloom frequency of green Noctiluca and other red tides according to the Asian monsoon seasons: the southwest monsoon (May–September) and the northeast monsoon (October–January of the following year). Green Noctiluca blooms occurred farther from the shore and estuaries than other red tides (dinoflagellates and cyanobacteria), and were much more frequent than other red tides between the Tha Chin and Chao Phraya River mouths during the non-monsoon period (February to April). The frequency and distribution of green Noctiluca blooms, as well as other algal blooms, varied with the monsoon season. By comparing MODIS-derived algal blooms to monsoon-induced factors (i.e., sea surface winds, precipitation, and river discharge), we present an unprecedented overview of the spatial and temporal dynamics of red tides throughout the uGoT under Asian monsoon conditions. This research contributes to our understanding of the impact of climate change on phytoplankton dynamics

Assessing the uncertainties of model estimates of primary productivity in the tropical Pacific Ocean

Author Posting. © Elsevier B.V., 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Marine Systems 76 (2009): 113-133, doi:10.1016/j.jmarsys.2008.05.010.Depth-integrated primary productivity (PP) estimates obtained from satellite ocean color based models (SatPPMs) and those generated from biogeochemical ocean general circulation models (BOGCMs) represent a key resource for biogeochemical and ecological studies at global as well as regional scales. Calibration and validation of these PP models are not straightforward, however, and comparative studies show large differences between model estimates. The goal of this paper is to compare PP estimates obtained from 30 different models (21 SatPPMs and 9 BOGCMs) to a tropical Pacific PP database consisting of ~1000 14C measurements spanning more than a decade (1983- 1996). Primary findings include: skill varied significantly between models, but performance was not a function of model complexity or type (i.e. SatPPM vs. BOGCM); nearly all models underestimated the observed variance of PP, specifically yielding too few low PP (< 0.2 gC m-2d-2) values; more than half of the total root-mean-squared model-data differences associated with the satellite-based PP models might be accounted for by uncertainties in the input variables and/or the PP data; and the tropical Pacific database captures a broad scale shift from low biomass-normalized productivity in the 1980s to higher biomass-normalized productivity in the 1990s, which was not successfully captured by any of the models. This latter result suggests that interdecadal and global changes will be a significant challenge for both SatPPMs and BOGCMs. Finally, average root-mean-squared differences between in situ PP data on the equator at 140°W and PP estimates from the satellite-based productivity models were 58% lower than analogous values computed in a previous PP model comparison six years ago. The success of these types of comparison exercises is illustrated by the continual modification and improvement of the participating models and the resulting increase in model skill.This research was supported by a grant from the National Aeronautics and Space Agency Ocean Biology and Biogeochemistry program (NNG06GA03G), as well as by numerous other grants to the various participating investigator