Search

Optical remote sensing is an applicable approach for red tide monitoring in wide observation range. This study proposed a red tide identification method using the logical operation of multi-band spectral indices (MBSIs). Five candidate MBSIs from two categories that could potentially indicate red tide outbreaks are selected and integrated into different combinations. The reflectance spectra of red tide measured in the Xinghai Bay, China, are used to determine the optimal combination of MBSIs through the self-organized map network. According to the result, the combination of fluorescence baseline height and the spectral difference indices at red and near-infrared bands achieves the highest accuracy at 0.95 among all the combinations of MBSIs. Therefore, the logical operation of these three MBSIs is applied to Sentinel-2 satellite images to identify red tide in coastal regions. It is found that the logic operation method of MBSIs can work robustly in different sea areas and provides more reasonable results than using any single MBSI. The proposed method is able to detect the red tide that are often undetectable by human eyes with low computational complexity, and can be applied to the rapid detection and daily surveillance on the spatial distribution of red tide outbreaks. [ABSTRACT FROM AUTHOR]

The article explores Indigenous modes of survival in the face of existential threats such as climate change, resource extraction, and pandemics. It highlights the Nez Perce tribe's reclaiming of ancestral land as a vibrant modality of survival in an alienated landscape. The text emphasizes the need to learn from Indigenous modes of being to navigate the challenges of the sixth extinction and planetary health. Through the concept of vibrant modalities, the article calls for a renewed kinship with the land to ensure survival in the face of impending upheavals. [Extracted from the article]

Algal blooms of Karenia brevis produce brevetoxins that lead to the natural phenomenon of red tide. Beyond monitoring the red tide concentration and forecasting future outbreaks, uncertainty exists in the field when examining these toxins in relation to the physiology of people. Contaminated air that results from outbreaks of K. brevis leads to inhalation of aerosolized brevetoxins, which directly impact the human respiratory system. This scoping review focused on the respiratory effects of red tide and was conducted by using a comparative method between 2 researchers. Relevant abstracts were collected, and full-text articles were reviewed by using PubMed, Science Direct, CINAHL Complete, and BioMed Central databases. Thirty articles were included in the final analysis and categorized by study design, location, and number and age of participants, and were also divided into assessment by respiratory effects, exposure, measurements of K. brevis, and asthma. The research indicates that respiratory health issues exist and can be compounded with exposure to red tide, specifically upper respiratory symptoms. Both symptomatic issues and pulmonary function tests were of concern when individuals were subjected to brevetoxin exposure. Even low levels of K. brevis resulted in negative respiratory health effects. Red tide is common in many areas of the world. The toxins released can cause adverse respiratory effects. This article provides a comprehensive summary of the scholarly literature focused on the respiratory system and red tide produced by K. brevis. [ABSTRACT FROM AUTHOR]

Drastic declines observed in coral reefs in response to changes in climate and other anthropogenic stressors have hinged the survival of these ecosystems largely on the overall health and reproductive success of stony corals. One specific threat, Karenia brevis blooms, has drawn increased public attention in recent decades and has been documented to reach the Florida Keys, a vulnerable coral ecosystem. The purpose of this study was to investigate the sublethal impact of K. brevis exposure on three South Florida "restoration" coral species. Fragments of Porites astreoides, Acropora cervicornis, and Siderastrea radians were exposed to three environmentally relevant concentrations of K. brevis for 2 weeks in a controlled aquaria setting. At the end of exposure, ultra-high-performance liquid chromatography coupled to high-resolution tandem mass spectrometry (UHPLC-HRMS/MS) was used to perform nontargeted lipidomics and metabolomics analyses to assess physiological changes in the corals in response to red tide exposure, as well as highlight possible biological processes and pathways altered. Significant changes to the lipidome and metabolome were observed in all three species following exposure. Furthermore, the multi-omics analysis highlighted important pathways for further study including impacts on oxidative stress, energy metabolism, the immune system, and nitrogen fixation/photosynthesis of symbionts. Due to the use of environmentally relevant exposure levels and duration, these results are invaluable to understand possible future impacts of red tide on coral reef areas as well as to inform future coral reef restoration and management decisions. [ABSTRACT FROM AUTHOR]

The states of Oregon and Connecticut and the District of Columbia in the USA mandate the teaching of menstrual education which means the teachers of students with disabilities are expected to be familiar with the topics of hygiene, self-care, and independent living skills in relation to menstrual health needs. Special education teachers may need to attend to pre-menstrual symptoms, collect data on challenging behaviour, and ensure their students have access to period products. Teachers can consult with parents about teaching these skills at home to ensure generalisation of skills across contexts, and to build strong communication between school and home. Teachers should also familiarise themselves with local resources for menstrual supplies and instructional materials for both students and parents. Teaching skills in relation to menstrual health is critical for increasing independence, maintaining individual dignity, and fostering a menstrual experience free of stigma and shame. [ABSTRACT FROM AUTHOR]

Japanese common squid Todarodes pacificus was exposed to the red tide-causing dinoflagellate Karenia mikimotoi, collected from a red tide event in Hakodate Port, in seawater at four densities (0, 90, 320, and 1900 K. mikimotoicells mL−1) for 24 h. The number of squids that sunk to the bottom every hour and the survival of squids were recorded every 3 h. Squids in the group exposed to the highest cell density of K. mikimotoi began to sink to the bottom within 1 h of the start of the exposure test, and the frequency of anomalies (sinking or death) was significantly higher in this group than in the other groups (Wilcoxon signed-rank test with Bonferroni correction, P-values < 0.001). Hazard ratios for squid mortality were affected by K. mikimotoi cell density (Cox proportional hazards model; P-values < 0.01). These results suggest that K. mikimotoi is harmful to the Japanese common squid and that even short-term exposure to high densities of this alga causes debilitation and loss of swimming ability, leading to death. The debilitation and death of the Japanese common squid by K. mikimotoi has the potential to cause a loss of freshness and a decline in their commercial value, as has been observed during red tide events. [ABSTRACT FROM AUTHOR]

Chlorophyll prediction facilitates the comprehension of red tide characteristics and enables early warning. In practice, it is formulated as a multivariate time series forecasting problem aimed at forecasting future chlorophyll concentrations by considering both exogenous factors and chlorophyll. However, the multi-step prediction of chlorophyll concentration poses a formidable challenge due to the intricate interaction between factors and the long temporal dependence between input sequences. In this work, we propose a Multi-attention Recurrent Neural Network (MaRNN) for the multi-step prediction of chlorophyll concentration. The MaRNN comprises an encoder incorporating two-stage spatial attention and a decoder employing temporal attention. The encoder first learns the significance of exogenous factors for prediction in the first phase, and subsequently captures the spatial correlation between the exogenous sequence and chlorophyll sequence in the second phase. The decoder further excavates input sequences that exhibit a strong correlation with the task through temporal attention module, thereby enhancing the prediction accuracy of the model. Experiments conducted on two real-world datasets reveal that MaRNN not only surpasses state-of-the-art methods in performance, but also offers interpretability for chlorophyll prediction. [ABSTRACT FROM AUTHOR]

Increasing human activities and climate change have resulted in significant changes in net primary production (NPP) of the marginal sea in the past several decades. The Bohai Sea (BHS) is a shallow semi‐enclosed marginal sea of North China, the knowledge of the relative impacts of human activities and climate change on the NPP in the BHS remains limited. This study primarily aimed to elucidate the interannual variability of NPP and its influencing factors in the BHS during the 2002–2021 period by synthesizing four widely‐used global NPP models, namely the vertically generalized production model (VGPM), the Eppley‐VGPM, the size‐fractioned phytoplankton pigment absorption‐based model (SABPM), and the carbon, absorption, and fluorescence euphotic‐resolving model (CAFE). The multi‐model average NPP showed significant interannual variation, with an increasing trend from 2002 to 2012 and a decreasing trend from 2012 to 2021. The concentration of DIN in the BHS was primarily affected by atmospheric nitrogen deposition. The structural equation model demonstrated that chlorophyll‐a (Chl‐a) concentration, influenced by DIN concentration, had an important effect on NPP. In brief, atmospheric nitrogen deposition impacted the DIN concentration and thus controlled the Chl‐a concentration and NPP change in the BHS. Furthermore, atmospheric nitrogen deposition in the BHS have potential ecological impacts on the red tide features. These findings hold valuable implications for future marine resource planning and marine ecological management in the BHS. Plain Language Summary: Marine net primary productivity (NPP) plays an important role in regulating marine ecosystem processes. Nearly half of the global photosynthesized carbon in ocean and the marginal sea account for 20%–30% of the total ocean productivity. The Bohai Sea is a shallow marginal sea in the northwest Pacific Ocean, strongly impacted by human activities, supporting high primary and fishery productivity. Using four widely‐used global NPP models, we observe the interannual variability of NPP and its influencing factors in the Bohai Sea during the 2002–2021 period. We found the NPP in the Bohai Sea showed an increasing trend from 2002 to 2012 and a decreasing trend from 2012 to 2021. The concentration of DIN in the Bohai Sea was primarily affected by atmospheric nitrogen deposition. Moreover, atmospheric nitrogen deposition impacted the DIN concentration and thus controlled the chlorophyll‐a concentration and NPP change of the Bohai Sea. The red tide features in the Bohai Sea seemed to be potentially related to the atmospheric nitrogen deposition. These findings provide valuable insights into the interannual trend of NPP in the Bohai Sea and its underlying mechanisms, and highlight the significant impact of human activities on the Bohai Sea environment. Key Points: The net primary production (NPP) in the Bohai Sea clearly shows the interannual‐decadal trendsThere is an increasing trend in the NPP from 2002 to 2012 and a decreasing trend from 2012 to 2021Atmospheric deposition controls the interannual variation of NPP by affecting the DIN concentration [ABSTRACT FROM AUTHOR]

The diatom Paralia guyana is a tychoplanktonic microalgal species that represents one of the early diverging diatoms. P. guyana can thrive in both planktonic and benthic habitats, making a significant contribution to the occurrence of red tide events. Although a dozen diatom genomes have been sequenced, the identity of the early diverging diatoms remains elusive. The understanding of the evolutionary clades and mechanisms of ecological adaptation in P. guyana is limited by the absence of a high-quality genome assembly. In this study, the first high-quality genome assembly for the early diverging diatom P. guyana was established using PacBio single molecular sequencing. The assembled genome has a size of 558.85 Mb, making it the largest diatom genome on record, with a contig N50 size of 26.06 Mb. A total of 27,121 protein-coding genes were predicted in the P. guyana genome, of which 22,904 predicted genes (84.45%) were functionally annotated. This data and analysis provide innovative genomic resources for tychoplanktonic microalgal species and shed light on the evolutionary origins of diatoms. [ABSTRACT FROM AUTHOR]

Breaking‐wave induced bioluminescence is a critical component of the biogeochemical process in the ocean. Understanding bioluminescence is important for monitoring red tides caused by bioluminescent microorganisms. In this study, we present the first numerical effort to quantify bioluminescent light intensity based on high‐fidelity direct numerical simulations of breaking waves and a quantitative bioluminescent model. The dynamics of breaking waves are extensively validated through comparison with existing studies. We find that the time‐averaged and Lagrangian‐averaged shear stress saturates as surface tension effects decrease and wave steepness increases. The spatial distribution of light intensity correlates with the wave crest overturning and air bubbles generated in plunging breakers. Furthermore, we observe that the maximum light intensity asymptotically approaches the emission of single cells, suggesting the potential for cost‐effective prediction models in future studies. Plain Language Summary: Marine microorganisms, such as dinoflagellates, flash when stimulated by mechanical forces caused by breaking waves. Understanding this phenomenon, also known as the 'blue tears' of ocean, is helpful for predicting 'red tides', a hazardous algal blooms caused by dinoflagellates. We use computer simulations to determine how much light is emitted when breaking waves stimulates bioluminescence. Our analysis show that there is an upper limit for the level of the mechanical force in breaking waves. We also find that the maximum bioluminescence light intensity is similar to that emitted by a single cell. Key Points: A numerical framework is developed to quantify bioluminescence stimulated by ocean surface breaking wavesThe time‐averaged and Lagrangian‐averaged shear stress saturates as surface tension effects decrease and wave steepness increasesMaximum bioluminescent light intensity asymptotically approaches single cell emission at the time of flashing [ABSTRACT FROM AUTHOR]

With the upcoming completion of the Moderate Resolution Imaging Spectroradiometer mission, this study applied 250-m-spatial-resolution ocean colour products from the Second-Generation Global Imager (SGLI) on the Global Change Observation Mission-Climate (GCOM-C) platform to continue monitoring red tides in the upper Gulf of Thailand. However, inaccuracies of GCOM-C/SGLI data on red tide detection were observed. To enhance its reliability, we first improved the accuracy of GCOM-C/SGLI remote sensing reflectance (Rrs) data by adjusting it to in situ data using wavelength-specific regression functions. This method significantly reduced the mean absolute percentage difference between in situ and GCOM-C/SGLI data by 25%–87% for single SGLI wavelengths and by 46%–83% for Rrs($\lambda $ λ)/Rrs(565) of the original data. Subsequently, we employed the corrected data of SGLI Rrs($\lambda)$ λ) at 565 nm and the ratios of Rrs(490)/Rrs(565), Rrs(530)/Rrs(565), and Rrs(673)/Rrs(565) in local empirical algorithms to estimate chlorophyll-a(chl-a) concentration and identify red tide waters. SGLI chl-a improved substantially in areas affected by red tides, particularly as chl-a concentrations increased. Additionally, the corrected GCOM-C/SGLI accurately identified red tides caused by green Noctiluca, diatoms, and dinoflagellate blooms consistent with local reports, confirming the GCOM-C/SGLI reliability enhancement. This method may serve as an alternative strategy for monitoring the red tides. [ABSTRACT FROM AUTHOR]

The Programmable Hyperspectral Seawater Scanner (PHySS) represents a significant breakthrough in monitoring harmful algal blooms (HABs), specifically targeting the "Florida red tide" caused by Karenia brevis. By utilizing a Fourth-Derivative Spectral Similarity Index (SI), this study establishes a strong positive correlation between the SI and phytoplankton counts, underscoring the PHySS's potential for early detection and effective management of HABs. Our findings suggest that the PHySS could act as a predictive tool, offering crucial lead time to mitigate the ecological and economic repercussions of blooms. However, this study also identifies certain limitations of the PHySS technology, such as its inability to differentiate among various phytoplankton species without additional physical verification of cell counts. This limitation highlights the need for a multifaceted approach to HAB management. Our research suggests that adopting a multi-modal monitoring strategy could lead to more sophisticated and effective methods for combating HABs, fostering an optimistic outlook for future advancements in this area. [ABSTRACT FROM AUTHOR]

Currently, the primary method for controlling red tides in the ocean involves spraying water solutions with special chemicals as solutes. High-pressure spraying results in the formation of typical jet structures. In this study, numerical simulation methods are employed to investigate the velocity variations, turbulent characteristics, and gas content distribution of jet flow fields under different initial jet flow pressures, cone angles, and nozzle diameters. Based on practical application scenarios, cluster analysis is used to explore the similarities and differences in jet equivalent diameters under different parameter conditions. The research findings indicate the following. (1) The difference of jet velocity distribution at the far field exit will be enlarged with the increase in the nozzle cone angle. When the nozzle cone angle is 4 mm, the velocity uniformity at the outlet is the best. (2) The TKE of the flow field has no consistent change law along the central axis. At the jet exit, the TKE shows an obvious multi-peak structure. (3) The gas content demonstrates a typical "double-valley" feature at the jet outlet cross-section. Increasing the initial pressure leads to a decrease in the gas content within the jet due to reduced entrainment, while the entrainment range remains largely constant. (4) Cluster analysis reveals that the similarity of jet flow width when it reaches the water surface is minimal compared to other operating conditions when the initial pressure is 0.36 MPa, the cone angle is 115°, and the nozzle diameter is 2 mm. All conditions can be categorized into two or three groups to ensure jet effectiveness. The study results provide scientific guidance for selecting spray devices for controlling red tides in the ocean. [ABSTRACT FROM AUTHOR]

Simple Summary: In China, in addition to green tides and red tides, outbreaks of Cnidaria (jellyfish organisms), Annelida (Urechis unicinctus Drasche, 1880), Mollusca (Philine kinglipini S. Tchang, 1934), Arthropoda (Acetes chinensis Hansen, 1919), and Echinodermata (Asteroidea organisms (commonly known as starfish), Ophiuroidea organisms, and Acaudina molpadioides Semper, 1867) not only damage marine resources, tourism, coastal industries, and navigation but also profoundly impact ecosystems near nuclear plants, beaches, and infrastructures, endangering human lives. This article suggests measures to mitigate future disasters, emphasizing enhanced monitoring and integration into China's marine ecological disaster monitoring system. This review is conducive to enhancing researchers' comprehension and reflection regarding biological disasters in marine ecosystems. Owing to global climate change or the ever-more frequent human activities in the offshore areas, it is highly probable that an imbalance in the offshore ecosystem has been induced. However, the importance of maintaining and protecting marine ecosystems' balance cannot be overstated. In recent years, various marine disasters have occurred frequently, such as harmful algal blooms (green tides and red tides), storm surge disasters, wave disasters, sea ice disasters, and tsunami disasters. Additionally, overpopulation of certain marine organisms (particularly marine faunas) has led to marine disasters, threatening both marine ecosystems and human safety. The marine ecological disaster monitoring system in China primarily focuses on monitoring and controlling the outbreak of green tides (mainly caused by outbreaks of some Ulva species) and red tides (mainly caused by outbreaks of some diatom and dinoflagellate species). Currently, there are outbreaks of Cnidaria (Hydrozoa and Scyphozoa organisms; outbreak species are frequently referred to as jellyfish), Annelida (Urechis unicinctus Drasche, 1880), Mollusca (Philine kinglipini S. Tchang, 1934), Arthropoda (Acetes chinensis Hansen, 1919), and Echinodermata (Asteroidea organisms, Ophiuroidea organisms, and Acaudina molpadioides Semper, 1867) in China. They not only cause significant damage to marine fisheries, tourism, coastal industries, and ship navigation but also have profound impacts on marine ecosystems, especially near nuclear power plants, sea bathing beaches, and infrastructures, posing threats to human lives. Therefore, this review provides a detailed introduction to the marine organisms (especially marine fauna species) causing marine biological disasters in China, the current outbreak situations, and the biological backgrounds of these outbreaks. This review also provides an analysis of the causes of these outbreaks. Furthermore, it presents future prospects for marine biological disasters, proposing corresponding measures and advocating for enhanced resource utilization and fundamental research. It is recommended that future efforts focus on improving the monitoring of marine biological disasters and integrating them into the marine ecological disaster monitoring system. The aim of this review is to offer reference information and constructive suggestions for enhancing future monitoring, early warning systems, and prevention efforts related to marine ecological disasters in support of the healthy development and stable operation of marine ecosystems. [ABSTRACT FROM AUTHOR]

Phytoplankton samples were collected both inside and outside a large scale raft mussel culture area of Gouqi island in September 2023. The diurnal variation characteristics of phytoplankton community inside and outside the culture area were analyzed by using abundance and diversity index and multivariate statistical methods. A total of 7 phyla and 158 species of phytoplankton were collected(103 species inside and 98 species outside the area), including 104 species of diatom(accounting for 65.82%), 30 species of Pyrrophyta(accounting for 18.99%), and 15.19% for the rest species. During the daytime, 94 species were collected in the inner area, while 103 species were collected at night. In the outer area, 93 species were collected during the daytime, and 98 species were collected at night. The dominant species of phytoplankton in the aquaculture area were 9 species, while in the outer area, there were 12 dominant species. Among them, Skeletonema costatum and Noctiluca scintillans were dominant species throughout the day in both areas. The average abundance of phytoplankton in the inner area was (1.77×107±2.5×106) cells/L during the daytime and (1.64×107±2.31×106) cells/L at night, while in the outer area, it was (1.87×107±3.36×106) cells/L during the daytime and (1.75×107±2.72×106) cells/L at night. The abundance variation in the inner area showed a multi-peak pattern, with peak values occurring during the rising and falling tides and the high tide. In contrast, the abundance variation in the outer area showed a single-peak pattern, closely related to tidal changes, with the peak value only occurring during the high tide.Non-metric multidimensional scaling (nMDS) analysis showed that there was no significant difference in phytoplankton community between day and night in the aquaculture area (P>0.05), but there was significant difference in phytoplankton community outside the area (P<0.05), which was significantly correlated with tidal changes (P<0.01). Temperature, dissolved oxygen and salinity were significantly correlated with the number and abundance of phytoplankton (P<0.05), the number of phytoplankton species was significantly negatively correlated with phosphate and nitrate (P<0.05), and the abundance was significantly positively correlated with ammonia nitrogen and silicate (P<0.05). The results showed that the impact of large-scale raft culture on phytoplankton community in local waters could present a more positive result at the stage of red tide organism aggregation. [ABSTRACT FROM AUTHOR]

The East China Sea frequently experiences red tide outbreaks, significantly impacting marine carbon sink dynamics and ecosystem health. This study examines the temporal and spatial variations of red tide events in the East China Sea 2012 -2021, utilizing MODIS remote sensing imagery with a focus on summer outbreaks. Using the Two-Step algorithm, we assess surface particle organic carbon (POC) levels in red tide-affected areas, providing crucial insights into the carbon sink potential and distribution patterns of phytoplankton. Key findings include: (1) The largest red tide outbreak area occurred in 2015, with substantial fluctuations observed along the Zhejiang coast compared to the more stable Yangtze River estuary, especially in 2018 and 2020. (2) Surface POC concentrations reached their peak at 404.37 g m−3 in the Yangtze River estuary in 2021 and 359.83 g m−3 along the Zhejiang coast in 2017, with the lowest values recorded in 2013 and 2015. (3) Spatially, The distribution of severe algal bloom and higher concentrations of POC are observed along the coastal areas of the Yangtze River estuary and Zhejiang-Fujian, but with different causes. These findings highlight the importance of red tide events in regional carbon dynamics and their role in achieving sustainable development goals. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Dalian University of Technology / Dalian Ligong Daxue Xuebao is the property of Journal of Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The abnormal reduction of kelp production occurred in Rongcheng area of the Yellow Sea in 2021, which is closely related to the red tide. However, the relationship between the red tide event and the hydrodynamic environment remains unclear. In response to these issues, this study established a coupled physical-biological model which coupling the ROMS dynamic model with the RED_TIDE biological model for the Yellow Sea and Bohai Sea region, and discussed driving factors of this red tide. Based on this coupled model, various factors influencing the development of red tide were investigated, with a focus on analyzing the key factors contributing to the occurrence of the red tide event in the northern sea area of the Shandong Peninsula in 2021. The aggregation of dinoflagellate cells triggers red tide events. The distribution characteristics and concentration changes of dinoflagellate cells were studied by designing simulation experiments under different conditions to reflect the contributions of various influencing factors to red tide. According to observation data and simulation experiments, this study explored the effects of factors such as light conditions, tides, Yellow River runoff and wind field on the distribution and concentration of dinoflagellate cells. The variation of wind field can promote the proliferation and aggregation of dinoflagellate cells, serving as key factors in triggering red tide. The occurrence of red tide is a complex ecological phenomenon influenced by multiple factors, necessitating the comprehensive consideration of these factors to more accurately predict and prevent red tide events. [ABSTRACT FROM AUTHOR]

We present a novel method for detecting red tide (Karenia brevis) blooms off the west coast of Florida, driven by a neural network classifier that combines remote sensing data with spatiotemporally distributed in situ sample data. The network detects blooms over a 1‐km grid, using seven ocean color features from the MODIS‐Aqua satellite platform (2002–2021) and in situ sample data collected by the Florida Fish and Wildlife Conservation Commission and its partners. Model performance was demonstrably enhanced by two key innovations: depth normalization of satellite features and encoding of an in situ feature. The satellite features were normalized to adjust for depth‐dependent bottom reflection effects in shallow coastal waters. The in situ data were used to engineer a feature that contextualizes recent nearby ground truth of K. brevis concentrations through a K‐nearest neighbor spatiotemporal proximity weighting scheme. A rigorous experimental comparison revealed that our model outperforms existing remote detection methods presented in the literature and applied in practice. This classifier has strong potential to be operationalized to support more efficient monitoring and mitigation of future blooms, more accurate communication about their spatial extent and distribution, and a deeper scientific understanding of bloom dynamics, transport, drivers, and impacts in the region. This approach also has the potential to be adapted for the detection of other algal blooms in coastal waters. Integr Environ Assess Manag 2024;20:1432–1446. © 2024 SETAC Key Points: We developed a novel machine learning‐based method for detecting red tide (Karenia brevis) blooms off the Florida Gulf Coast at a 1‐km spatial resolution.We present a quantitative comparison of state‐of‐the‐art satellite methods for detecting K. brevis.The use of both satellite data as well as recent in situ samples produces better model prediction than either individually. [ABSTRACT FROM AUTHOR]

The dinoflagellate Karenia selliformis forms red tides in coastal waters and damages fishery industries in some countries, although its toxicity remains understudied. In recent years, blooms of K. selliformis have killed a vast amount of marine organisms on the Pacific coast of Hokkaido, Japan, representing the first reports of fishery damage by K. selliformis in this country. It is necessary to understand the lethal density of K. selliformis to marine organisms and environmental conditions that increase its toxicity to establish an alert level for K. selliformis red tides. In the present study, we aimed to identify the level of toxicity to fish of K. selliformis and its environmental modulators by conducting a toxicity assay with medaka fish (Oryzias latipes). First, medaka was exposed to the culture strain of K. selliformis isolated from coastal waters in Hokkaido and a culture strain of a noxious red-tide dinoflagellate Karenia mikimotoi. As a result, the toxicity of K. selliformis was extremely high compared to that of K. mikimotoi. Next, we examined growth and toxicity to O. latipes of K. selliformis cultured under several light intensities. The K. selliformis culture strain could grow at more than 20 µmol photons m-2 s-1, and its maximum growth rate reached 0.54 day-1 at 400 µmol photons m-2 s-1. The toxicities of K. selliformis grown under different light intensities positively correlated with its growth rates. Our results revealed that K. selliformis exerts strong toxicity under moderate light intensity, suggesting that its high toxicity to fish requires its active growth. [ABSTRACT FROM AUTHOR]

The changes in the cell physiology (growth rate, cell size, and cell DNA content), photosynthetic efficiency, toxicity, and sexuality under variable light and nutrient (phosphates) conditions were evaluated in cultures of the dinoflagellate Alexandrium minutum obtained from a red tide in the Ría de Vigo (NW Spain). The cells were grown at low (40 and 150 µE m−2 s−1), moderate (400 µE m−2 s−1), and high (800 µE m−2 s−1) light intensities in a medium with phosphate (P+) and without (P−). Cultures were acclimated to the irradiance conditions for one week, and the experiment was run for ~1 month. The cell size and DNA content were monitored via flow cytometry. Two different clonal strains were employed as a monoculture (in a P− or P+ medium) or, to foster sexuality and resting cyst formation, as a mixed culture (only in a P− medium). A. minutum growth was favored by increasing light intensities until 400 µE m−2 s−1. The DNA content analyses indicated the accumulation of S-phase cells at the highest light intensities (400 and 800 µE m−2 s−1) and therefore the negative effects on cell cycle progression. Only when the cells were grown in a P− medium did higher light intensities trigger dose-dependent, significantly higher toxicities in all the A. minutum cultures. This result suggests that the toxicity level is responsive to the combined effects of (high) light and (low) P stress. The cell size was not significantly affected by the light intensity or P conditions. The optimal light intensity for resting cyst formation was 150 µE m−2 s−1, with higher irradiances reducing the total encystment yield. Encystment was not observed at the lowest light intensity tested, indicative of the key role of low-level irradiance in gamete and/or zygote formation, in contrast to the stressor effect of excessive irradiance on planozygote formation and/or encystment. [ABSTRACT FROM AUTHOR]

Marine dinoflagellate species in the genus Alexandrium are well known to produce paralytic shellfish poison as well as common coastal species with cosmopolitan distribution. However, few studies on the feeding of copepods on Alexandrium species have been conducted. The toxic dinoflagellate Alexandrium pseudogonyaulax contains goniodomin A and causes red tides in many countries. To investigate the relationship between the toxic dinoflagellate A. pseudogonyaulax and the calanoid copepods Acartia spp., we quantified the ingestion rates of Acartia spp. feeding on A. pseudogonyaulax as a function of prey concentration. Additionally, we estimated grazing coefficients by integrating data from field observations of Acartia spp. and coexisting A. pseudogonyaulax with laboratory measurements of ingestion rates obtained during this investigation. Furthermore, we compared the ingestion rates of Acartia spp. and other predators feeding on Alexandrium species as previously reported. The ingestion rates of Acartia spp. on A. pseudogonyaulax increased continuously with increasing mean prey concentration. The highest values among the ingestion rate of Acartia spp. feeding on A. pseudogonyaulax was 3,407 cells predator-1 d-1 (4,872 ng C predator-1 d-1) at the given prey concentration. The calculated grazing coefficients for Acartia spp. on A. pseudogonyaulax in Shiwha Bay, Korea, were up to 0.073 d-1. The results of this study suggest that A. pseudogonyaulax may decrease or maintain the population of Acartia spp. in marine food webs. [ABSTRACT FROM AUTHOR]

Watersheds require collective care and management at local and regional levels to maintain their ecological health. The Chesapeake Bay's last several decades of stagnantly poor ecological health presents a distinctive case study for explicating the challenges of motivating collective action across a diverse regional natural resource. Our study uses county- and individual-level descriptive analysis to examine interrelated framings of environmental quality, environmental sentiment, and political action at two critical moments in time—the 2016 and 2020 presidential elections. We find that demographic, environmental, and political characteristics vary with distance to the Chesapeake Bay and that linked environmental and political characteristics appeared to become more polarized between 2016 and 2020. We found no evidence that local environmental quality influenced new political actions such as voting; however, people already likely to vote were influenced by their pro-environmental values such as priorities around climate change. [ABSTRACT FROM AUTHOR]

Despite increased attention to the aquaculture environment, there is still a lack of understanding regarding the significance of water quality. To address this knowledge gap, this study utilized high-throughput sequencing of 16S rRNA and 18S rRNA to examine microbial communities (bacteria and eukaryotes) in coastal water over different months through long-term observations. The goal was to explore interaction patterns in the microbial community and identify potential pathogenic bacteria and red tide organisms. The results revealed significant differences in composition, diversity, and richness of bacterial and eukaryotic operational taxonomic units (OTUs) across various months. Principal coordinate analysis (PCoA) demonstrated distinct temporal variations in bacterial and eukaryotic communities, with significant differences (P = 0.001) among four groups: F (January-April), M (May), S (June–September), and T (October-December). Moreover, a strong association was observed between microbial communities and months, with most OTUs showing a distinct temporal preference. The Kruskal–Wallis test (P < 0.05) indicated significant differences in dominant bacterial and eukaryotic taxa among months, with each group exhibiting unique dominant taxa, including potential pathogenic bacteria and red tide organisms. These findings emphasize the importance of monitoring changes in potentially harmful microorganisms in aquaculture. Network analysis highlighted positive correlations between bacteria and eukaryotes, with bacteria playing a key role in network interactions. The key bacterial genera associated with other microorganisms varied significantly (P < 0.05) across different groups. In summary, this study deepens the understanding of aquaculture water quality and offers valuable insights for maintaining healthy aquaculture practices. Key points: • Bacterial and eukaryotic communities displayed distinct temporal variations. • Different months exhibited unique potential pathogenic bacteria and red tide organisms. • Bacteria are key taxonomic taxa involved in microbial network interactions. [ABSTRACT FROM AUTHOR]

Contaminants from wastewater of aquaculture are increasing the risks of red tides in coastal areas. Such types of contaminants are difficult to remove by using conventional biological and ecological treatment methods because of the relatively low C/N ratios and the high salinity in coastal water ambience. Fe is considered a key element in natural chemical cycling and promotes the growth of animals and plants as well. The cycling of Fe ion combined with carbon, nitrogen, and phosphorus stimulates bacterial growth. As a result, it acts as a microbial carbon pump in coastal areas, such as natural wetlands, which have been activated and adapted to be salinity resistant and insufficient energy supply. Along these lines, in this work, constructed wetlands (CWs) with high ecological benefits and low cost of maintenance were used to treat aquaculture wastewater. The impact of Fe ion recycling on multiple contaminants was also systematically investigated. The two types of Fe dosage were pure ferrous ions and a mixture of iron powder and ferrous ions. After the application of a 3-day treatment, the dosage of iron powder/ferric ions (1:1 m/m) at a concentration of 15 mg L−1 showed a better effect, where the total nitrogen, total phosphorus, and chemical oxygen demand removal rates were increased by 2.95%, 2.16%, and 9.76%, respectively. From the microbial analysis, it was indicated that Fe ion affected the abundance and functions of the microbial communities in the CWs. The significant enrichment of Proteobacteria promoted the removal of multiple contaminants under saline stress and fixed carbon, and affected the whole microbe distribution and diversity in CWs. The implementation of such an environmentally friendly and economical approach arises as a promising candidate for the efficient removal of multiple contaminants from aquacultural wastewater in coastal zones. [ABSTRACT FROM AUTHOR]

The potential of diatoms as aquatic bait, attribute to their abundance in highly unsaturated fatty acids, has been extensively studied. Temperature plays a crucial role in the synthesis of these fatty acids. This study specifically investigated the impact of temperature on the growth, total lipid content, and fatty acid composition of Skeletonema dohrnii, a planktonic diatom commonly associated with red tides andwater blooms in China. The aim is to evaluate its suitability as an aquatic bait and provide insights for large-scale factory farming. Results indicated that the highest biomass and maximum growth rate occurred at 28°C, with no significant deviation from the control group at 25°C. At 28°C and 15°C, there was a significant increase in the total lipid content and the total fatty acid content, with a more pronounced effect at 15°C. At 28°C, EPA and DHA content measured at 0.97 ± 0.01 mg.DW.L-1 and 0.264 ± 0.01 mg.DW.L-1 respectively, surpass those at 15°C due to lower biomass. Conversely, at 15°C, substantial synthesis of long-chain polyunsaturated fatty acids, with EPA constituting up to 32.24 ± 0.24% of the total fatty acids, is observed. Modulating the temperature could optimize the utilization of S. dohrnii as an aquatic feed source. These findings underscore the potential of S. dohrnii as a high-quality aquafeed and lay the groundwork for its success in ocean warming scenarios. [ABSTRACT FROM AUTHOR]

Many dinoflagellate species are bioluminescent, which is one of the anti-predation mechanisms in these species. In addition, dinoflagellate species experience a wide range of salinities in the ocean. However, the effects of salinity on their bioluminescence intensity has only been investigated for one species. Here, we explored the effect of salinity on the bioluminescence intensity of the heterotrophic dinoflagellate Noctiluca scintillans NSDJ2010 feeding on the chlorophyte Dunaliella salina, the heterotrophic dinoflagellate Polykrikos kofoidii PKJH1607 feeding on the dinoflagellate Alexadrium minutum, and the autotrophic dinoflagellate Alexandrium mediterraneum AMYS1807. Moreover, to determine the cell volume and growth effects on bioluminescence intensity, the cell volume and growth rate of three bioluminescent dinoflagellates were simultaneously investigated. The mean 200-s-integrated bioluminescence intensity (BL) per cell, equivalent to the total bioluminescence, of N. scintillans, P. kofoidii, and A. mediterraneum was significantly affected by salinity and increased with increasing salinity from 10 to 40. The results of the present study suggest that the total bioluminescence of N. scintillans, P. kofoidii, and A. mediterraneum in offshore and oceanic waters is greater than that in estuarine waters. [ABSTRACT FROM AUTHOR]

Despite the fact that the first red tide reported on the coasts of the Iberian Peninsula was due to Lingulodinium polyedra, knowledge about their frequency and, particularly, about the environmental conditions contributing to bloom initiation is still scarce. For this reason, L. polyedra bloom episodes were observed and studied in three Galician rias during the summer season based on the 1993–2008 record database period; additionally, samples were collected in summer 2008. Proliferations of L. polyedra occurred in the rias of Ares and Barqueiro in June and August, respectively, while in the Ria of Coruña, they persisted from the end of June to early September. Red tides developed when the surface temperature reached 17 °C, with "seasonal thermal window" conditions, and when salinities were ≥30, i.e., an "optimal salinity window"; when these parameters were lower than these thresholds, cyst germination decreased. A cyst transport mechanism from sediments to the surface must also exist; this mechanism was found to be natural (tidal currents) in the ria of Barqueiro or anthropogenic (dredging) in the rias of Ares and Coruña. Surface temperatures during summer were usually favorable for cyst germination (85 to 100%) during the 1993–2008 period; however, water temperatures below 10 m depth only rarely reached the 17 °C threshold (2 to 18%). During this 16-year period, dredging activities could explain 71% (Coruña) and 44% (Ares) of the recorded bloom events. When a bloom episode developed in early summer, favorable conditions did not lead to a new red tide, probably due to the lag period required by cysts for germination. Moreover, blooms did not develop when high densities of diatoms (>1,000,000 cells·L−1) remained in the water column as a result of summer upwelling pulses occurring in specific years. The temperature–sediment disturbance pattern found in this study provides a useful tool for the prevention of eventual risks resulting from red tides of this dinoflagellate. [ABSTRACT FROM AUTHOR]

As one of the worst ecological disasters in the world's oceans, red tide seriously threatens marine ecology. Red tide monitoring is essential for preserving the ocean ecosystem. However, traditional photogrammetric processing workflows, e.g. SfM (Structure from Motion) and MVS (Multi-view Stereo) based image orientation and dense matching, do not apply to offshore images due to the low texture of ocean color. The primary contribution of this study is a UAV (Unmanned Aerial Vehicle)-based photogrammetric solution for red tide monitoring and direct geo-localization. First, a direct geo-localization model has been created, which solely uses onboard sensor data for the 3D coordinate calculation of 2D image targets based on the collinear equation. Second, two UAVs are chosen as photogrammetric systems that can supply the necessary data for the direct geo-localization model, including high-resolution images, camera intrinsic and extrinsic parameters. Third, a human annotation technique has been utilized to identify red tide regions whose ground polygons can be further estimated using the direct geo-localization model, taking into account how difficult it is to detect red tides automatically. Finally, the accuracy of direct geo-localization and the viability of the proposed solution has been evaluated and verified using real UAV datasets. The experimental results show that the direct geo-localization precision is better than 20 m when only onboard sensor data is used. The suggested workflow is appropriate for monitoring red tides, which can provide critical information for managing marine ecosystems. The executable toolkit would be made publicly available at https://github.com/json87/PhotoDigitizer. [ABSTRACT FROM AUTHOR]

Plankton blooms are complex nonlinear phenomena whose occurrence can be described by the two-timescale (fast-slow) phytoplankton-zooplankton model introduced by Truscott and Brindley (Bulletin of Mathematical Biology 56(5):981–998, 1994). In their work, they observed that a sufficiently fast rise of the water temperature causes a critical transition from a low phytoplankton concentration to a single outburst: a so-called plankton bloom. However, the dynamical mechanism responsible for the observed transition has not been identified to the present day. Using techniques from geometric singular perturbation theory, we uncover the formerly overlooked rate-sensitive quasithreshold which is given by special trajectories called canards. The transition from low to high concentrations occurs when this rate-sensitive quasithreshold moves past the current state of the plankton system at some narrow critical range of warming rates. In this way, we identify rate-induced tipping as the underlying dynamical mechanism of largely unpredictable plankton blooms such as red tides, or more general, harmful algal blooms. Our findings explain the previously reported transitions to a single plankton bloom, and allow us to predict a new type of transition to a sequence of blooms for higher rates of warming. This could provide a possible mechanism of the observed increased frequency of harmful algal blooms. [ABSTRACT FROM AUTHOR]

Curcumin, a natural plant product, was investigated as a mitigation tool against Karenia brevis, the toxic dinoflagellate responsible for Florida red tides. A series of laboratory bench-top studies were conducted with additions of 0.1, 1, 2, 3, 5, 10, 20, 30, and 40 mg/L curcumin to K. brevis at an average of 1.0 × 106 cells/L to determine the efficacy of curcumin against K. brevis cells and brevetoxins and to optimize treatment dosage. Treatment with 5 mg/L of curcumin reduced K. brevis cell abundance by 89% and total brevetoxins by 60% within 24 h. Lower concentrations of curcumin (0.1–3 mg/L) exhibited between a 2 and 45% reduction in K. brevis and a reduction in brevetoxins of between 2 and 44% within 24 h. At the highest curcumin doses, 30 and 40 mg/L, a 100% reduction in cell abundance was observed by 6 h, with reduction in total brevetoxins by at least 64% in 48 h. These results suggest that curcumin, used alone or potentially in combination with other technologies, is a promising K. brevis bloom mitigation option. [ABSTRACT FROM AUTHOR]

This study investigated how nitrogen and dissolved organic matter (DOM) from stormwater runoff and rainfall support the growth of Karenia brevis and Pyrodinium bahamense. Excitation–emission matrix spectroscopy coupled with parallel factor analysis tracked changes in the optical properties of DOM in each bioassay, revealing greater reactivity of terrestrial humic-like DOM. Significant increases in cell yield and specific growth rates were observed upon additions of runoff for both species, with significant increases in specific growth rates upon the addition of a 2 in simulated rain event for P. bahamense only. By hour 48, 100% of the dissolved organic nitrogen (DON) in each treatment was utilized by P. bahamense, and by hour 72, over 50% of the DON was utilized by K. brevis. The percentage of bioavailable dissolved organic carbon (DOC) was greater for P. bahamense compared to K. brevis, suggesting a greater affinity for DOC compounds by P. bahamense. However, the bioavailability of DOM for each species could be owed to distinct chemical characteristics of labile DOM conveyed from each site. This study demonstrates that stormwater runoff and rainfall are both sources of labile DOM and DON for K. brevis and P. bahamense, which has implications for blooms of these species in Tampa Bay waters. [ABSTRACT FROM AUTHOR]

Chlorophyll-a (Chl-a) concentration monitoring is very important for managing water resources and ensuring the stability of marine ecosystems. Due to their high operating efficiency and high prediction accuracy, backpropagation (BP) neural networks are widely used in Chl-a concentration inversion. However, BP neural networks tend to become stuck in local optima, and their prediction accuracy fluctuates significantly, thus posing restrictions to their accuracy and stability in the inversion process. Studies have found that metaheuristic optimization algorithms can significantly improve these shortcomings by optimizing the initial parameters (weights and biases) of BP neural networks. In this paper, the adaptive nonlinear weight coefficient, the path search strategy "Levy flight" and the dynamic crossover mechanism are introduced to optimize the three main steps of the Artificial Ecosystem Optimization (AEO) algorithm to overcome the algorithm's limitation in solving complex problems, improve its global search capability, and thereby improve its performance in optimizing BP neural networks. Relying on Google Earth Engine and Google Colaboratory (Colab), a model for the inversion of Chl-a concentration in the coastal waters of Hong Kong was built to verify the performance of the improved AEO algorithm in optimizing BP neural networks, and the improved AEO algorithm proposed herein was compared with 17 different metaheuristic optimization algorithms. The results show that the Chl-a concentration inversion model based on a BP neural network optimized using the improved AEO algorithm is significantly superior to other models in terms of prediction accuracy and stability, and the results obtained via the model through inversion with respect to Chl-a concentration in the coastal waters of Hong Kong during heavy precipitation events and red tides are highly consistent with the measured values of Chl-a concentration in both time and space domains. These conclusions can provide a new method for Chl-a concentration monitoring and water quality management for coastal waters. [ABSTRACT FROM AUTHOR]

With the advancement of global maritime transport, the carriage of foreign organisms by vessels is inciting ecological catastrophes such as red tides, posing a grave threat to China's marine environmental security. Clarifying the geographical distribution of invasive species and their relationship with climate change can provide scientific basis for their prevention and control. In this discourse, the study centers on the typical alien microalgae, Nitzschiella closterium. By integrating environmental variables and distribution data and employing an optimized Maxent model, we delve into its potential distribution in current and future ecological conditions in the coastal waters of China, as well as the response relationship to environmental variables. After model optimization, the results reveal that the Area Under the Curve (AUC) value of the training dataset for Nitzschiella closterium stands at 0.993, denoting a high degree of model accuracy and bestowing credibility upon the simulated outcomes. Currently, the high suitability area constitutes 0.74% of the total suitability area, with an area of 0.44×104 km², and is mainly distributed in the sea area corresponding to Jiangsu Province, Shanghai City, and Zhejiang Province. The most significant environmental factor affecting the geographical distribution of Nitzschiella closterium is the annual temperature variation range (bio24). In the context of future climate changes, there is an overall trend of substantial expansion in the high suitability area for Nitzschiella closterium, which is profoundly affected by climate change, suggesting that the future control will be more severe. This research comprehensively understands the response relationship of the invasive species Nitzschiella closterium to leading environmental variables and its potential geographical distribution in the context of climate change through macro prediction and proposes control countermeasures. It will provide a scientific basis for preventing and controlling Nitzschiella closterium invasions. [ABSTRACT FROM AUTHOR]

Through statistical analysis of the red tides that occurred in the coastal waters of Tianjin from 2001—2020, it was found that in recent years, the occurrence of red tide in Tianjin coastal seawater exhibits high-frequency, small-scale characteristics. The annual cumulative duration of red tide from 2012 to 2020 shows a general increasing trend, which is mainly controlled by DIP. Summer months were the peak periods of red tide, especially in June and August, the duration of a single red tide was long. Red tide causing species was evolving toward dinoflagellates in the Tianjin coastal seawater. Noctiluca scintillans, Skeletonema costatum and Pseudo-nitzschia pungens caused the most red tide, these three types of algae have the characteristic of alternating over time to become the causing species, mainly due to their adaptability to the hydrological environment. Toxic red tides mainly occurred from June to September, the red tides that occurred in September were mostly toxic. The toxic red tide species in Tianjin coastal waters are mostly Cochlodinium polykrikoides and Gymnodinium mikimotoi.

This document is an editorial published in the journal Frontiers in Marine Science. It discusses the biogeochemical responses to physical processes in the North Pacific and its adjacent marginal seas. The editorial highlights the importance of understanding the effects of physical processes, such as wind-driven mixing, boundary currents, and upwelling, on ocean chemical compounds, primary productivity, and carbon sequestration. The document also mentions eight research articles included in the special volume, which cover various aspects of biogeochemical responses to physical processes, including the impact of tropical cyclones on nutrient supply and phytoplankton blooms, the influence of mesoscale eddies on biological activity, and the driving factors of red tides. The editorial concludes by emphasizing the complexity of marine biogeochemical responses to physical processes and the need for further research in this field. [Extracted from the article]

Highly migratory shorebirds are among the fastest declining avian guilds, so determining causes of mortality is critically important for their conservation. Most of these species depend on a specific geographic arrangement of suitable sites that reliably provide resources needed to fuel physiologically demanding life histories. Long-term mark-resight projects allow researchers to investigate specific potential sources of variation in demographic rates between populations. Red Knots (Calidris canutus) occur in three relatively distinct regions across the northern Gulf of Mexico, and two of these areas have been experiencing episodic harmful algal blooms (red tide) with increased frequency in recent decades. Since knots are mostly molluscivorous during the nonbreeding season in the Gulf, they are potentially exposed to red tide toxins at high concentrations via their filter-feeding prey. We used long-term mark-resight data from Texas, Louisiana, and Florida (USA) to estimate apparent survival, and to assess the effects of red tides on survival of Red Knots. We also assessed effects of tracking devices deployed in conjunction with the projects over the years. While overall apparent annual survival rates were similar across the three locations (0.768-0.819), several red tide events were associated with catastrophically low seasonal (fall) survival in Florida (as low as 0.492) and Texas (as low as 0.510). Leg- mounted geolocators, but not temporary glued-on VHF tags, were associated with a reduction in apparent survival (~8%/year). Movement of knots between the three areas was rare and site fidelity is known to be high. Harmful algal blooms are predicted to increase in frequency and severity with climate change and increased anthropogenic degradation of coastal habitats, which may further endanger these as well as other shorebird populations around the world. [ABSTRACT FROM AUTHOR]

Harmful blooms of the marine dinoflagellate Kai·enia brevis form over the West Florida Shelf in the Gulf of Mexico and can be transported toward the coast of southwest Florida by currents and winds nearly annually. Once on the coast. blooms can be intensified by multiple factors including anthropogenic land-based nitrogen loads. This study investigates the relationship between two management endpoints: land-based nitrogen loads and the duration of red tide events. For the purposes of this effort. a red tide event was defined as a period exhibiting maximum daily K brevis cell counts >100.000 cells/L or > 10.000 cells/'L for at least 30 days within the study area-between Estero Bay and Sarasota Bay-and considered total nitrogen (TN) loads from the Myakka. Peace (inclusive of Horse Creek and Joshua Creek). and Caloosahatchee Rivers occurring within 130 days of the onset of red tide events. TN loads from the Caloosaliatchee Rii·er exhibited statistically significant correlations with red tide ej·ent duration (under both definitions of a red tide event) whereas TN loads from the Peace and Myakka Rivers did not exhibit such correlations. The results suggest that policy and management efforts to reduce nitrogen loading may substantially reduce the duration of red tide events in southwest Florida. [ABSTRACT FROM AUTHOR]

Simple Summary: Florida red tides are large algal blooms of the toxic organism Karenia brevis and can have severe ecological impacts along the Gulf Coast regions of Florida, USA. K. brevis blooms produce potent neurotoxins, known as brevetoxins, which are known to cause disease and mortality in various marine species, including sea turtles. This review examines the impact of red tides on sea turtle health by discussing K. brevis blooms in general, as well as the toxin exposure routes and mechanisms of disease. Diagnostic and treatment options are also discussed. Significant research efforts have focused on developing improved therapeutic interventions, and intravenous lipid emulsion therapy has proven highly effective at rapidly alleviating symptoms and accelerating brevetoxin removal from sea turtles. This review synthesizes the current scientific understanding of red tide impacts on threatened and endangered sea turtle health. Continued investigations of outstanding knowledge gaps may help mitigate the threat of harmful algal blooms on sea turtles in the future and may contribute to the conservation of sea turtles. This review summarizes the current understanding of how brevetoxins, produced by Karenia brevis during harmful algal blooms, impact sea turtle health. Sea turtles may be exposed to brevetoxins through ingestion, inhalation, maternal transfer, and potentially absorption through the skin. Brevetoxins bind to voltage-gated sodium channels in the central nervous system, disrupting cellular function and inducing neurological symptoms in affected sea turtles. Moreover, the current evidence suggests a broader and longer-term impact on sea turtle health beyond what is seen during stranding events. Diagnosis relies on the detection of brevetoxins in tissues and plasma from stranded turtles. The current treatment of choice, intravenous lipid emulsion therapy, may rapidly reduce symptoms and brevetoxin concentrations, improving survival rates. Monitoring, prevention, and control strategies for harmful algal blooms are discussed. However, as the frequency and severity of blooms are expected to increase due to climate change and increased environmental pollution, continued research is needed to better understand the sublethal effects of brevetoxins on sea turtles and the impact on hatchlings, as well as the pharmacokinetic mechanisms underlying brevetoxicosis. Moreover, research into the optimization of treatments may help to protect endangered sea turtle populations in the face of this growing threat. [ABSTRACT FROM AUTHOR]

Nitrogen and phosphorus play essential roles in ecosystems and organisms. However, with the development of industry and agriculture in recent years, excessive N and P have flowed into water bodies, leading to eutrophication, algal proliferation, and red tides, which are harmful to aquatic organisms. Biochar has a high specific surface area, abundant functional groups, and porous structure, which can effectively adsorb nitrogen and phosphorus in water, thus reducing environmental pollution, achieving the reusability of elements. This article provides an overview of the preparation of biochar, modification methods of biochar, advancements in the adsorption of nitrogen and phosphorus by biochar, factors influencing the adsorption of nitrogen and phosphorus in water by biochar, as well as reusability and adsorption mechanisms. Furthermore, the difficulties encountered and future research directions regarding the adsorption of nitrogen and phosphorus by biochar were proposed, providing references for the future application of biochar in nitrogen and phosphorus adsorption. [ABSTRACT FROM AUTHOR]

Many dinoflagellates produce bioluminescence. To estimate the intensity of bioluminescence produced by populations of the heterotrophic dinoflagellates Noctiluca scintillans and Polykrikos kofoidii and autotrophic dinoflagellate Alexandrium mediterraneum in Korean waters, we measured cellular bioluminescence intensity as a function of water temperature and calculated population bioluminescence intensity with cell abundances and water temperature. The mean 200-second-integrated bioluminescence intensity per cell (BLcell) of N. scintillans satiated with the chlorophyte Dunaliella salina decreased continuously with increasing water temperature from 5 to 25°C. However, the BLcell of P. kofoidii satiated with the mixotrophic dinoflagellate Alexandrium minutum continuously increased from 5 to 15°C but decreased at temperatures exceeding this (to 30°C). Similarly, the BLcell of A. mediterraneum continuously increased from 10 to 20°C but decreased between 20 and 30°C. The difference between highest and lowest BLcell of N. scintillans, P. kofoidii, and A. mediterraneum at the tested water temperatures was 3.5, 11.8, and 21.0 times, respectively, indicating that water temperature clearly affected BLcell. The highest estimated population bioluminescence intensity (BLpopul) of N. scintillans in Korean waters in 1998-2022 was 4.22 × 1013 relative light unit per liter (RLU L-1), which was 1,850 and 554,000 times greater than that of P. kofoidii and A. mediterraneum, respectively. This indicates that N. scintillans populations produced much brighter bioluminescence in Korean waters than the populations of P. kofoidii or A. mediterraneum. [ABSTRACT FROM AUTHOR]

Algal blooms are a pervasive problem for Florida, and successful management decisions must rely on the best available science. In 2019, Florida Sea Grant convened a forum of harmful algal bloom (HAB) scientists for the first Harmful Algal Bloom State of the Science Symposium. The goals of the two-day forum were to develop consensus statements identifying the current state of the science regarding what we know and what we think we know, data gaps and areas of uncertainty, and research priorities, with a focus on Karenia brevis red tides and Microcystis aeruginosa cyanobacterial blooms. In 2023, Florida Sea Grant convened a second symposium at the request of the state. This symposium focused specifically on cyanobacteria and assessed progress made over the four-year period between symposia. Consensus statements summarizing what we've learned, new research priorities, and best practices for cyanobacterial HAB research and management efforts were developed. The symposia consensus reports are used to inform Florida's Harmful Algal Bloom and Blue-Green Algae Task Forces by aligning and prioritizing the management and research needs of the agencies and scientific institutions and to facilitate cohesive public outreach. [ABSTRACT FROM AUTHOR]

Mesodinium rubrum is a kleptoplastidic ciliate that sequesters the chloroplasts and nuclei of cryptophyte algae to perform photosynthesis. Blooms of M. rubrum can cause red tides in coastal oceans worldwide. Such red tides are detectable by remote sensing, and studying M. rubrum pigments and optical properties is a crucial step toward characterizing its blooms using satellite observation. Previous studies have shown that M. rubrum photoacclimates, modifying its pigment content depending on irradiance. Using cultures at different irradiance levels, we observed that photoacclimation in M. rubrum closely resembles that of its cryptophyte prey Teleaulax amphioxeia , leading to substantial phenotypic variability. In both species, phycoerythrin 545 cellular concentrations increased 3-fold between the highest and lowest irradiance, suggesting a major role in photoacclimation. Absorption cross-section decreased, and pigment-specific absorption coefficients increased with irradiance at the peak absorption wavelengths of chlorophyll a and phycoerythrin 545. After assessing the variability of absorption properties in M. rubrum , we combined field measurements and high-resolution Sentinel-2 satellite images to estimate chlorophyll a concentration of a coastal red tide and document small-scale spatio-temporal features. This work provides an overview of pigment photoacclimation in a peculiar phytoplankter and suggests guidelines for future studies of M. rubrum blooms. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

"Red tide" is the popular name for a harmful algal bloom that occurs frequently in Florida waters and has significant impacts on the environment, the economy, and human and animal health. This paper addresses the limited understanding of public attitudes surrounding red tide and the potential for message framing to increase support for mitigation action. A sample of Florida residents (n = 498) was randomly shown a digital article framed around different red tide impacts (economic loss, human health risks, ecosystem damage, or harm to charismatic species) or a control article not framed around a specific red tide impact. Participants were then queried about their emotional responses, support for red tide mitigation policies, and intentions to change their behavior to mitigate impacts. Participants reported higher levels of negative emotions after viewing the harm to charismatic megafauna framing, indicating that messaging may play a significant role in eliciting environmental emotions. Message frames did not significantly impact other policy attitudes. Results demonstrate barriers to shifting support for mitigation where public support for action is already high. [ABSTRACT FROM AUTHOR]