red tide
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2022 ◽  
Author(s):  
Marcus Beck ◽  
Andrew Altieri ◽  
Christine Angelini ◽  
Maya Burke ◽  
Jing Chen ◽  
...  

From March 30th to April 9th, 2021, 814 million liters of legacy phosphate mining wastewater and marine dredge water from the Piney Point facility were released into lower Tampa Bay (Florida, USA). This resulted in an estimated addition of 186 metric tons of total nitrogen, exceeding typical annual external nitrogen load estimates to lower Tampa Bay in a matter of days. Elevated levels of phytoplankton (non-harmful diatoms) were first observed in April in the lower Bay. Filamentous cyanobacteria blooms (Dapis spp.) peaked in June, followed by a bloom of the red tide organism Karenia brevis. Reported fish kills tracked K. brevis concentrations, prompting cleanup of over 1600 metric tons of dead fish. Seagrasses had minimal changes over the study period. By comparing these results to baseline environmental monitoring data, we conclude that many of the biological responses observed after the release from Piney Point are abnormal relative to historic conditions.


Harmful Algae ◽  
2022 ◽  
Vol 111 ◽  
pp. 102149
Author(s):  
Shane D. Ross ◽  
Jeremie Fish ◽  
Klaus Moeltner ◽  
Erik M. Bollt ◽  
Landon Bilyeu ◽  
...  
Keyword(s):  

2022 ◽  
Author(s):  
Miles Medina ◽  
David Kaplan ◽  
Eric C. Milbrandt ◽  
Dave Tomasko ◽  
Ray Huffaker ◽  
...  

2021 ◽  
Vol 14 (1) ◽  
pp. 88
Author(s):  
Xin Zhao ◽  
Rongjie Liu ◽  
Yi Ma ◽  
Yanfang Xiao ◽  
Jing Ding ◽  
...  

Existing red tide detection methods have mainly been developed for ocean color satellite data with low spatial resolution and high spectral resolution. Higher spatial resolution satellite images are required for red tides with fine scale and scattered distribution. However, red tide detection methods for ocean color satellite data cannot be directly applied to medium–high spatial resolution satellite data owing to the shortage of red tide responsive bands. Therefore, a new red tide detection method for medium–high spatial resolution satellite data is required. This study proposes the red tide detection U−Net (RDU−Net) model by considering the HY−1D Coastal Zone Imager (HY−1D CZI) as an example. RDU−Net employs the channel attention model to derive the inter−channel relationship of red tide information in order to reduce the influence of the marine environment on red tide detection. Moreover, the boundary and binary cross entropy (BBCE) loss function, which incorporates the boundary loss, is used to obtain clear and accurate red tide boundaries. In addition, a multi−feature dataset including the HY−1D CZI radiance and Normalized Difference Vegetation Index (NDVI) is employed to enhance the spectral difference between red tides and seawater and thus improve the accuracy of red tide detection. Experimental results show that RDU−Net can detect red tides accurately without a precedent threshold. Precision and Recall of 87.47% and 86.62%, respectively, are achieved, while the F1−score and Kappa are 0.87. Compared with the existing method, the F1−score is improved by 0.07–0.21. Furthermore, the proposed method can detect red tides accurately even under interference from clouds and fog, and it shows good performance in the case of red tide edges and scattered distribution areas. Moreover, it shows good applicability and can be successfully applied to other satellite data with high spatial resolution and large bandwidth, such as GF−1 Wide Field of View 2 (WFV2) images.


2021 ◽  
Author(s):  
Ahmed Elshall ◽  
Ming Ye ◽  
Sven Kranz ◽  
Julie Harrington ◽  
Xiaojuan Yang ◽  
...  

2021 ◽  
Vol 22 (4) ◽  
Author(s):  
Galyna Terenko ◽  
Alexander Krakhmalnyi

One of the most massive red tides at the Odessa Bay was observed in September October 2020. It was caused by a toxic dinoflagellate Lingulodinium polyedrum (Stein) Dodge. The maximum abundance (56.1 x 106 cells L-1) of L. polyedrum was registered at the Odessa port area on October 6 when a water temperature and a salinity were 19.7°C and 14.3 ‰ respectively. The red tide was so huge and dense that the water glowed at night due to the bioluminescence characteristic of this species. The article briefly describes the history of the study of L. polyedrum in this area and provides a detailed morphological description with original photographs of this species sampled from bloom. We associate the appearance of the red tide with an increased temperature of sea water and air, a high content of nutrients, the presence of viable L. polyedrum cysts, and a slight decrease in salinity in the bay during the period of a mass development of the species in autumn of 2020. The red tide was accompanied by Protoperidinium steini, P. divergens, Prorocentrum cordatum, P. minimum, P. micans, Gonyaulas scrippsae, Diplopsalis lenticula, Azadinium spinosum, Dinophysis rotundata, D. acuminata, Oblea rotunda, Scrippsiella trochoidea, Ceratium furca.


2021 ◽  
Vol 8 ◽  
Author(s):  
Jeffery Liang-Neng Lee ◽  
Kuo-Ping Chiang ◽  
Sheng-Fang Tsai

Noctiluca scintillans is a larger, bioluminescent red-tide dinoflagellate (400–1,000 μm in diameter) that reproduces by sexual or asexual reproduction (binary fission). The process of sexual reproduction in N. scintillans has been thoroughly studied, but the ecological role and the mechanism of shifting from asexual to sexual reproduction have not been fully elucidated. It is believed, however, that sexual reproduction occurs when N. scintillans faces environmental stress. In this study, we tried to determine which factors drive N. scintillans to undergo sexual reproduction and we considered sexual reproduction’s ecological role. We cultured N. scintillans under different conditions of temperature, N. scintillans cell concentration, prey concentration, cultivation time, cultivation volume, light exposure time and physical vibration (simulated wave motion), and counted gametocyte mother cells every 24 h to calculate how the sexual reproduction rate changed over the experimental period. Rises in the sexual reproduction rate or the concentration of gametocyte mother cells only occurred in response to large variations in prey concentration, typically after the exponential phase of N. scintillans population growth. A noticeable upsurge in gametocyte mother cells, from 1% or less to nearly 10% of the total N. scintillans population, occurred when the prey concentration fell below ∼400 cells/mL. This implies that a sudden decrease in prey concentration induces more N. scintillans to shift from trophonts to gametocyte mother cells. We suggest that sexual reproduction may occur in N. scintillans as a response to the post-bloom situation when the dinoflagellate’s food supply has been dramatically depleted, producing large numbers of gametes for an alternative mode of survival after the end of each bloom.


Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7344
Author(s):  
Zhiming Guo ◽  
Hanbo Deng ◽  
Jiajin Li ◽  
Ran Liao ◽  
Hui Ma

Suspended particles affect the state and vitality of the marine ecosystem. In situ probing and accurately classifying the suspended particles in seawater have an important impact on ecological research and environmental monitoring. Individual measurement of the optical polarization parameters scattered by the suspended particles has been proven to be a powerful tool to classify the particulate compositions in seawater. In previous works, the temporal polarized light pulses are sampled and averaged to evaluate the polarization parameters. In this paper, a method based on dense sampling of polarized light pulses is proposed and the experimental setup is built. The experimental results show that the dense sampling method optimizes the classification and increases the average accuracy by at least 16% than the average method. We demonstrate the feasibility of dense sampling method by classifying the multiple types of particles in mixed suspensions and show its excellent generalization ability by multi-classification of the particles. Additional analysis indicates that the dense sampling method basically takes advantage of the high-quality polarization parameters to optimize the classification performance. The above results suggest that the proposed dense sampling method has the potential to probe the suspended particles in seawater in red-tide early warning, as well as sediment and microplastics monitoring.


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