Search

The current study is the first to document a vast swarm of the pelagic tunicate Thalia democratica inshore of the Egyptian Mediterranean waters. On the May 05, 2021, a swarm of the Salpida T. democratica was discovered inshore of the coast of Stanley. The swarm coincided with a red tide bloom in the research area. The documented species is given a brief redescription with illustrative photographs, taxonomic annotations, habitat notes, and distribution.

Skeletonema costatum is a diatom widely distributed in red tide microalgae blooms and as one of the main algae causing harmful algal blooms, because of their rapid reproduction and production of toxic and harmful substances, often play a negative role in aquatic ecosystems, and human health and wellbeing. Bacillomycin D is a nonribosomal cyclic antifungal lipopeptide in the iturins family. In this study, synthetic Bacillomycin D was tested for its ability to inhibit the growth of S. costatum. The EC50. 24h of Bacillomycin D on S. costatum was 24.70 μg/mL. The chlorophyll fluorescence parameters Fv/Fm, Fv/Fo, and yield of the diatoms decreased significantly with increasing concentrations of Bacillomycin D. Study of the mechanism showed that Bacillomycin D induced cell death by changing cell membrane permeability, promoting the release of cellular contents. In this study, transcriptomic analysis showed Bacillomycin D significantly inhibited the photosynthesis and metabolism of S. costatum. These findings investigated the inhibitory effect of Bacillomycin D on the growth of S. costatum and provided a theoretical foundation for the development of new environmentally friendly biological algicide.

Red tides have many harmful effects on offshore ecosystem and even human health, which has become a global marine environmental problem. In recent years, the occurrence of red tides has become more...

Short-term changes in red tide characteristics are very helpful in monitoring the larger change progress and associations with environmental factors. We conducted an experiment to collect data on s...

Qarun Lake is a unique saline basin. Its phytoplankton species abundance and dynamics in relation to the Red Tide phenomenon is the focus of this study. Samples were collected from May 2015 to April 2016 in twelve successive cruises. Phytoplankton productivity attained the highest level on July with the bloom of Dinophyceae, while showing negative correlation with water transparency (r = −0.72) and positive correlation with DO (r = 0.84). The causative species was Gymnodinium lantzschii. Another incident of Dinophyceae bloom was observed in March when chlorophyll a recorded 158.4 mgm−3, chl. b was (92.7 mgm−3 and chl. c was 160 mgm−3. The causative species were Prorocentrum aporum and Prorocentrum micans and the lake’s water turned to red color; the “Red Tide phenomenon”. Chlorella vulgaris bloom was recorded for the first time in the lake on August at site (4) with green water discoloration. The water temperature of the lake was one of the main phytoplankton bloom’s drivers as the dominant species grew and flourished within a narrow range of temperature (30.4–34.9 °C). The results showed that there were strong correlations between carbonate, bicarbonate, DO and nutrients indicating that the dinoflagellate bloom was due to the high eutrophication of the lake. Finally, the Red tide phenomenon may influence the lake fisheries causing significant economic loss.

Long-term trends of bottom-water concentrations of dissolved oxygen (DO), total nitrogen, and total phosphorus at 42 sites in Tokyo Bay were analyzed using monthly data from 1983 to 2018 measured by local government agencies. The results were visualized as spatial distribution maps. Bottom-water DO concentrations varied seasonally. The area of hypoxic bottom water (DO

Polyaluminum chloride modified clay (PAC-MC) is a safe and efficient red tide control agent that has been studied and applied worldwide. Although it is well known that the distribution of hydrolytic aluminum species in PAC affects its flocculation, little is known about the influence of particulars aluminum species on the microalgae removal efficiency of PAC-MC; this lack of knowledge creates a bottleneck in the development of more efficient MCs based on aluminum salts. The ferron method was used in this study to quantitatively analyze the distributions of and variations in different hydrolytic aluminum species during the process of microalgae removal by PAC-MC. The results showed that Ala, which made up 5%–20% of the total aluminum, and Alp, which made up 15%–55% of the total aluminum, significantly affected microalgae removal, with Pearson's correlation coefficients of 0.83 and 0.89, respectively. Most of the aluminum in the PAC-MC sank rapidly into the sediments, but the rate and velocity of settlement were affected by the dose of modified clay. The optimal dose of PAC-MC for precipitating microalgae was determined based on its aluminum profile. These results provide guidance for the precise application of PAC-MC in the control of harmful algal blooms.

Based on the Ricker-type models, the spawning stock-recruitment (S-R) relationship of Portunus trituberculatus was analysed under the impacts of environmental factors (including red tide area (AORT), sea level height (SLH), sea surface salinity (SSS) and typhoon landing times (TYP)) in the northern East China Sea in 2001 and 2014. Besides the traditional Ricker model, two other Ricker-type S-R models were built: Ricker model with ln-linear environmental impact (Ricker-type 2) and Ricker model with ln-quadratic polynomial environmental impact (Ricker-type 3). Results showed that AORT, SLH, SSS and TYP had great influences on the recruitment of P. trituberculatus. When SSS reached 29 and 31, recruitment decreased from 20.7×103 million to 8.3×103 million individuals. In this case, recruitment declined, whereas AORT and TYP increased. Analysis of the S-R model showed that the Akaike information criterion (AIC) value of the traditional Ricker model was 14.619, which remarkably decreased after addition of the environmental factors. Different numbers of environmental factors were added to the Ricker model, and the best result was obtained when four factors were added to the model together. Moreover, Ricker-type 2 model, with the AIC value of −5.307, was better than Ricker-type 3 model (add above four environmental factors at the same time). The findings indicated that the mechanisms by which various environmental factors affect the S-R relationship are different.

Impacts of Karenia brevis red tide blooms have been an increasing cause of concern for fisheries management in the Gulf of Mexico (Gulf). The 2019 Gulf red grouper (Epinephelus morio) stock assessment was confronted with the challenges of quantifying and parameterizing red tides during both historical and projection time periods. Red tide mortality was estimated for each age class in the model solely in 2005 and 2014 during severe events. Given the considerable uncertainty surrounding the 2018 red tide and its substantial implications on the status of the population, several projection scenarios were evaluated. Under the assumption of no 2018 red tide mortality, near-term catches were projected to nearly double, a predicted outcome that appeared to be in contrast with recent record low catches and fishing industry perceptions of major stock depletion. In the event that the 2018 red tide caused mortality, but was not accounted for in projections, the recommended catch levels would lead to high probabilities of overfishing and potentially stock collapse. Collectively, these results highlight how consideration of uncertainty in projections can help avoid unintended consequences.

This scoping review is to better understand the interrelationships between temperature changes, chemical contaminants, and the characteristics of HABs (frequency, distribution, etc.). Research question: What are the impacts of temperature change and chemical contaminants on the frequency, distribution and other characteristics of HABs? We will conduct a scoping review to get an overview of the association between temperature, chemical contaminants, and HABs. This approach will explore the existing literature based on the following key terms. Problem: HABs in Florida/ Gulf of Mexico; Exposure: chemical contaminants and temperature and precipitation; Outcome: frequency, distribution and other characteristics of HABs in Florida.

Vitamins are an important growth factor for the majority of microalgae. Although the effects of light and prey availability on the growth and feeding of mixotrophic dinoflagellates are relatively w...

The presence and status of harmful algal blooms (HABs) in Japan are reviewed, revealing a decrease in red tides; however, toxic blooms are found to be increasing in western Japan. Environmentally friendly control strategies against HABs are also compared with integrated agricultural pest management. Very high densities (105–108 CFU/g) of algicidal and growth-inhibiting bacteria were found in biofilm on seagrass and seaweed surfaces and in surrounding coastal seawater. The situation in freshwater ecosystems is similar to coastal seas for toxic cyanobacterium,Microcystis aeruginosa, and aquatic plants. These findings offer new insights into the ecology of influential bacteria and harmful algae, suggesting that protection and restoration of native seagrasses and seaweeds in coastal marine environments should be implemented to suppress HABs. Diatom blooms were successfully induced with bottom sediment perturbation to prevent the occurrence of harmful flagellates such asChattonellaspp. andAlexandrium catenellain the Seto Inland Sea; however, this method requires robust and reproducible verification. “Sato-Umi” is a helpful concept for HAB control in the sea and freshwater ecosystems when adequately managed by people (e.g., appropriate bottom perturbation; protection and restoration of seaweeds, seagrasses, and aquatic plants; application of polycultures of fish, seaweeds, etc.).

To better understand the effect of typhoons on the harmful alga Cochlodinium polykrikoides, we investigated cell population dynamics in relation to hydrographic conditions in Korean coastal waters before and after the passage of typhoons. After typhoon Lingling passed through the Yellow Sea, significant accumulation of C. polykrikoides on the southern coast of Namhae Island was associated with southerly winds on September 8, 2019. Similar to field observations of red tide, a particle transport model simulation showed that the virtual particles were greatly influenced by wind-driven currents associated with typhoons, particularly when diel vertical migration was included in the model. However, a bloom of C. polykrikoides disappeared immediately after the passage of typhoon Tapah on September 23, 2019. Because of the different patterns of bloom behavior after the passage of these typhoons, characteristics of other typhoons that affected the Korean peninsula during previous C. polykrikoides blooms were investigated. Analysis of typhoon properties including wind direction, precipitation, and wave height and energy suggested that high wave energy during the passage of a typhoon plays a critical role in the termination of C. polykrikoides blooms, because of its generation of high turbulence relative to other factors. In our study, the wave energy associated with typhoon Tapah (753.6 kJ m−2 over 48 h) was much higher than that associated with typhoon Lingling (441.7 kJ m−2 over 48 h). The results indicate that typhoons have an important role in determining the accumulation and termination of C. polykrikoides blooms through the physical effects of wind direction and wave energy.

Between 1973 and 2017, evidences of red tide outbreaks and oil spill accidents in the Chinese coastal waters were collected. Statistical analysis and multiple regression models were used to determine the relationship between the red tide and the oil spill. Major findings reveal that (1) the frequency of red tides positively correlates to the number of oil spills and the volume of oil spilled as well; (2) the higher percentage of small spills (< 7 tonnes) are more likely to enhance the outbreaks of red tides; (3) both EI Nino and storm events do not show any relationship with red tides; and (4) more severe oil spill with penalty recorded implies a higher possibility to trigger the red tide afterwards. Therefore, oil spill contingency management focusing on small oil spills and mitigating their spill effect by physical measures could be of benefit to decrease the frequency of red tides significantly. For example, it is suggested to carry out physical combat instead of chemical dispersants to remove the spilled small oil in the shallow coastal areas for reducing the outbreak risk of red tides after the oil spill.

A natural compound with the algicidal effect was isolated from the culture medium of Aspergillus sp. SCSIOW2 and was identified as malformin C, which was based on the data of 1H-NMR, 13C-NMR, and ESI-MS. Malformin C exhibited dose-dependent algicidal activities against two strains of noxious red tide algae, Akashiwo sanguinea and Chattonella marina. The activity against A. sanguinea was stronger than that against C. marina (the algicidal activity of 58 and 36% at 50 μM treatment for 2 h, respectively). Morphology changes including perforation, plasmolysis, and fragmentation of algal cells were observed. Malformin C induced a significant increase in ROS level, caused the damage of SOD activity, and led to the massive generation of MDA contents in algae cells. To our knowledge, this is the first report of the cyclic peptide described as an algicidal compound against HABs.

A ten-year chlorophyll-a concentration dataset from Moderate Resolution Imaging Spectro-radiometer (MODIS) were used to analyze the variation of phytoplankton biomass and its potential relation with climate in the East China Sea. The result indicated that the phytoplankton biomass generally had a regular pattern every year, and phytoplankton bloom mainly occurred between May and July. The highest phytoplankton biomass appeared near the Yangtze River Estuary. The lowest phytoplankton biomass located near the Taiwan Strait. In general, the starting bloom time was earlier in the south than in the north, and the span time of the former was also longer. During the recent ten years, the phytoplankton biomass around the Yangtze River Estuary decreased obviously. The change of phytoplankton biomass was found to be related with the Nino 3.4 Index. The correlation between the intensity of phytoplankton bloom with the number and square of red tide were 0.63 and 0.74, respectively.

Eutrophication is a serious phenomenon that leads to vigorous algal blooms that alters the structure of ecosystems. It is caused by non-point sources of nutrients; as nitrogen and phosphorus, and point sources as wastewater effluent. Distinctive algae groups are responsible for this phenomenon, such as diatoms, blue-green algae, green algae, and dinoflagellates. Numerous solutions have been considered to control eutrophication and harmful algal blooms such as the biological removal of nitrogen and phosphorus. Advanced treatments (i.e. green technology) depend upon the remediation of wastewater before discharge, such as the removal of phosphorus using agricultural waste-based biosorbents (AWBs) from water and wastewater, and phosphorus sorption performance by both unmodified and modified AWBs. Phyto-remediation includes many procedures that encompass the cost-effective and environmentally friendly methods used to remove or reduce excess natural/inorganic contaminants in groundwater, surface water, and soil. Due to the rapid growth of duckweeds and their ability to rapidly remove minerals as phosphates and nitrogen from the water, duckweed may be the most promising plant for controlling eutrophication and, therefore, harmful algal blooms.

Abstract The results of space monitoring of an extreme ecological situation near Kamchatka Peninsula, which was responsible for a mass death of hydrobionts in autumn 2020, are presented. The analysis of long-term series of satellite data (>15 000 scenes) on sea surface temperature (from 1981 to 2020) and concentration of chlorophyll a (from 2000 to 2020) showed strong positive temperature anomalies (deviations from a climate norm 3–6°C) in the studied region in July–September 2020, which resulted in anomalous increase in the concentration of chlorophyll a (5–8 times higher than the background values) in the end of September–the beginning of October 2020. As a result, a significantly changed biogenic regime led to harmful bloom of algae (red tide), which caused death of hydrobionts both in Avacha Bay and coastal regions of the entire Kamchatka Peninsula.

The ethanol extracts of Gracilaria lemaneiformis that have inhibitory effects on Karenia mikimotoi and Skeletonema costatum were separated by liquid-liquid extraction using different polar solvents into five fractions with antialgal activities (petroleum ether, chloroform, ethyl acetate, n-butanol, and water-soluble fractions). These fractions were chromatographed on silica gel to give, after repeated preparative thin-layer chromatography (PTLC) purification processes, 1-β-D-ribofuranosyluracil (1), 3-hydroxymethyl-pyrrolopiperazine-2,5-dione (2), benzene-1,2-propanoic acid (3), 1-O-palmitoyl-2-O-palmitoleoyl-3-O-β-D-galactopyranosyl glycerol (4), 7-oxabicyclo[4.1.0]-heptan-3-ol (5), linoleic acid (6), 3,4-dimethoxy-6-(methoxymethyl)-tetrahydro-2H-pyran-2,5-diol (7), and 3,7,11,16-tetramethyl -2-heptadecen-1-ol (8). Five of them, natural products 1, 2, 5, 7, and 8, were isolated from Gracilaria lemaneiformis for the first time, and three natural products (3, 5, and 8) were isolated from marine macroalgae for the first time. Among them, natural products (1, 2, 3, 4, and 6) showed the most obvious inhibition activities to the growth of Karenia mikimotoi and Skeletonema costatum at the concentration of 80 μg/mL. Therefore, antialgal activities of these five natural products against Amphidinium carterae, Heterosigma akashiwo, Karenia mikimotoi, Phaeocystis globosa, Prorocentrum donghaiense, and Skeletonema costatum were further tested at different concentrations (0.4, 2, 10, and 50 μg/mL). This was the first report of antialgal activities of five natural products (1, 2, 3, 4, and 6) to these six red tide microalgae. They showed significantly selective antialgal activities against all tested red tide microalgae. At the concentration of 50 μg/mL, the growth of Amphidinium carterae, Heterosigma akashiwo, Karenia mikimotoi, and Phaeocystis globosa was obviously inhibited; for Karenia mikimotoi, natural products 1, 2, and 6 have significant antialgal activities; the growth inhibition of Skeletonema costatum that was exposed to natural products 1, 3, and 4 was remarkable. Furthermore, by analyzing and comparing EC50-96 h values, it has been determined that natural product 3 (natural product 4) showed the superior application potential than potassium dichromate and some reported natural products (such as gossonorol isolated from Porphyra yezoensis, trehalose purified from Ulva pertusa) as a characteristic antialgal agent against Amphidinium carterae (Phaeocystis globosa). In addition, natural products 1 and 3 also showed good superiority than some reported natural products in inhibiting Skeletonema costatum; however, it was a pity that they were inferior to potassium dichromate in the inhibiting this red tide microalgae. Taken together, it is not hard to conclude that Gracilaria lemaneiformis was a good source of natural products with antialgal activities against some red tide microalgae.

Dinoflagellates form a large group of microalgae that have different pigments and the pigment content can vary depending on environmental conditions such as temperature, salinity, and their growth phase. They have the potential to cause red tides in coastal waters, so it is important to identify their pigments. In this study, two bloom forming dinoflagellate species, Scrippsiella trochoidea and Gyrodinium instriatum from the Oman Sea, were studied for their pigment content by HPLC every 5 days over a 30-day growth period. In both species, 10 pigment types were identified: unknown carotenoids, chlorophyll (chl) c2, peridinin, peridinin-like, diadinochrome, diadinoxanthin, dinoxanthin, diatoxanthin, chl a, and β,β-carotene. Although both species have the same pigment types, they vary in concentration in different days of growth. The highest cell density in S. trochoidea species was on day 15 of the growth period and the predominant pigments were chl c2, diadinoxanthin, and chl a. Peridinin, peridinin-like, diadinochrome, and β,β-carotene were predominant pigments on day 10, before the cell reached its maximum density. In G. instriatum, the highest cell density during the growth period was in day 10. The highest levels of unknown carotenoids, chl c2, diadinoxanthin, dinoxanthin, peridinin, peridinin-like, diadinochrome, and β,β-carotene pigments were measured on day 25 of growth. The type of chloroplast in both species was the peridinin type. In interpreting the pigment concentration and type, the age of the species should be considered.

Con el propósito de describir las condiciones ambientales y climáticas asociadas con la ocurrencia de seis eventos de mareas rojas entre 2010 y 2017 en Santa Marta (Caribe colombiano), se recopiló la información biológica y fisicoquímica obtenida durante estos eventos. Adicionalmente, se consultaron los datos de precipitación y el Índice Oceánico de El Niño (ONI) entre 2010 y 2017. Los resultados mostraron que el dinoflagelado Cochlodinium sp. fue el responsable de tres eventos ocurridos en octubre de 2010, octubre de 2011 y noviembre de 2015, períodos en los que alcanzó densidades máximas de 5 × 106 cél. L-1. Estos eventos se asociaron con un incremento en las precipitaciones y la temperatura superficial del agua de mar (29,7 ºC) y con un descenso en la salinidad (< 35,5). El ciliado Mesodinium cf. rubrum fue responsable de otros tres eventos (enero de 2015, enero de 2017 y marzo de 2017), períodos en los que registró concentraciones máximas de 9.2 × 106 cél. L-1. Durante estos últimos eventos, no se presentaron precipitaciones y se evidenciaron elevadas concentraciones de nutrientes, incrementos en la salinidad (> 36,6) y temperaturas del mar inferiores a 26 ºC. Al asociar las ocurrencias de mareas rojas y los valores del índice ONI, se evidenció que las floraciones de Cochlodinium sp. ocurrieron durante años influenciados por eventos climáticos (térmicos) moderados y fuertes (ONI > ±1 ºC) en tanto que las floraciones de M. cf. rubrum se presentaron durante años neutrales (ONI entre 0,5 y -0,5 ºC). Las mareas rojas presentaron un patrón temporal de ocurrencia en la región del Magdalena, influenciadas por la variabilidad climática y ambiental de cada época, sin representar hasta el momento un riesgo para la salud humana.

Some species of Rhizosolenia form intense blooms, known as red tides, in Japanese coastal waters. In Tokyo Bay, Rhizosolenia setigera frequently causes red tides and sometimes causes discolouration...

The mucus produced by the outbreak of Phaeocystis globosa in the adjacent waters of the Fangchenggang Nuclear Power Plant (FCGNPP) in China has blocked the entrance of the cooling water filtration system of the FCGNPP, and posed a threat to the safe operation of the FCGNPP. At present, there is no related research on whether the changes in seawater viscosity could be used as a new method for monitoring and providing early warning of P. globosa tide. During a complete red tide cycle, the temporal and spatial changes in the hydrological conditions (temperature, salinity, dissolved oxygen), chlorophyll-a (Chl-a), composition and abundance of phytoplankton, number and size of P. globose colonies, concentration of transparent exopolymer particles (TEP) and the seawater viscosity were measured in this study. The results indicate that there was an extremely significant negative correlation between the physical seawater viscosity ηT,S and temperature, and the correlation coefficient reached −0.998. The biological seawater viscosity ηBio was positively correlated with the number of P. globosa colonies, and the correlation coefficients is 0.747. Because the increase in phytoplankton abundance, especially during the outbreak of P. globosa and a large amount of mucus produced by the colonies could significantly increase seawater viscosity, we suggest that biological factors were the main reasons for the increase in seawater viscosity. The ηBio was completely consistent with the occurrence process of P. globosa bloom and could be used as a valuable index for P. globosa bloom monitoring.

The effect of an electron beam on the toxic microalgae Cochlodinium polykrikoides and Alexandrium catenella, which are involved in the phenomenon of seawater blooming known as red tides, has been studied. This annual disaster causes mass intoxication and death of marine life. Electron-beam irradiation at an absorbed dose of to 1 kGy leads to inactivation of more than 2/3 of the microalgae population due to disruption of cell walls, damage to chloroplasts, and cell aggregation. Radiolysis destroys paralytic toxins, including the most dangerous of them. Because of low doses and the ease of irradiation, the electron-beam treatment of water can be a promising method for the inactivation and detoxification of phytoplankton involved in red tides.

The lifecycle of red tide forming dinoflagellate Noctiluca scintillans (Ehrenberg) McCartney was investigated from the estuarine waters of Cochin and also from their clonal cultures. Reproductive divisions including asexual binary fission and sexual isogamete formation were studied. Certain vegetative cells were observed to undergo binary fission. Gametocyte mother cells underwent meiosis followed by several synchronous mitotic divisions which resulted in the production of 256–1024 mature spindle-shaped haploid isogametes attached on the surface of the gametocyte mother cell body. After several hours, gametes were observed to fuse and form diploid zygotes. The zygote underwent differentiation from spindle to spherical, with a reduction in the flagellar number and develops into a minuscule trophont. These trophonts later attained maturity as the cell size increased. The life cycle of Noctiluca scintillans thus appear to be a diplontic type. Hence, the study illustrates different life cycle stages of N. scintillans based on both in-situ and clonal culture studies. In-situ life cycle study is first of its kind in the reproductive biology of the species.

Harmful algal blooms (HABs) can be a natural hazard unlike anything else. Whereas a hurricane or tornado has a sudden and devastating impact to an area, an HAB can slowly impact people and the environment over the course of weeks, even months. Karenia brevis, more commonly known as red tide, can have this effect along the Gulf Coast of Florida, lasting for many weeks in a row, causing large-scale deaths in fish and other marine life, and respiratory issues in humans. These harmful effects can effect tourism, as visitors are not able to enjoy the coastlines Florida is famous for. We test a 6 county region, from Pinellas County, FL down to Collier County, FL, to determine the magnitude with which an additional day of red tide affects tourism-related revenues. Using a spline regression approach, we find that an additional day of red tide in a month with 17 days or more of red tide drives monthly lodging sector sales down by 1–2%, and restaurant sector sales down by 0.5–1%. As these blooms are increasing in frequency and persistency, it becomes of great importance to counties and effected businesses to control and mitigate red tide blooms as soon as possible. If not, losses and harmful effects will only continue to grow and become detrimental to the environment and economy.

Recent marine and freshwater algal and cyanobacterial blooms in Florida have increased public concern and awareness of the risks posed by exposure to these organisms. In 2018, Lake Okeechobee and the Caloosahatchee river, on the west coast of Florida, experienced an extended bloom of Microcystis spp. and a bloom of Karenia brevis in the coastal waters of the Gulf of Mexico that coincided in the Fort Myers area. Samples from the Caloosahatchee at Fort Myers into Pine Island Sound and up to Boca Grande were collected by boat. High concentrations of microcystin-LR were detected in the cyanobacterial bloom along with brevetoxins in the marine samples. Furthermore, β-N-methylamino-L-alanine (BMAA) and isomers N-(2-aminoethyl)glycine (AEG) and 2,4-diaminobuytric acid (DAB) were detected in marine diatoms and dinoflagellates, and cyanobacteria of freshwater origin. High freshwater flows pushed the cyanobacterial bloom to barrier island beaches and Microcystis and microcystins could be detected into the marine environment at a salinity of 41 mS/cm. For comparison, in 2019 collections of Dapis (a new generic segregate from Lyngbya) mats from Sarasota showed high concentrations of BMAA, suggesting the possibility of long-term exposure of residents to BMAA. The findings highlight the potential for multiple, potentially toxic blooms to co-exist and the possible implications for human and animal health.

Harmful algal blooms occur when toxin-producing algae grow rapidly. These occur worldwide and have significant impacts on aquatic ecosystems and on human health. Specifically, the toxic blooms of Karenia brevis in Florida may affect humans via inhalation or ingestion. On retrospective reviews, health care costs appear to rise during these outbreaks because of respiratory and gastrointestinal manifestations. Treatment for exposure is supportive care, though traditional inhalers may help with respiratory complications.

Florida’s Gulf Coast is known as a retirement hotspot, with property values along the coast rising faster than almost anywhere else in the country. However, the coastal amenities that help boost prices, quickly turn to dis-amenities when there is a prolonged red tide bloom in the Gulf. Using a difference in differences hedonic valuation model, we examine six Southwestern Florida counties heavily impacted by four major algal bloom in the past 20 years. We find that affected properties within 1 mile of the coast sell for up to 30% less compared to similar homes sold during the same month in an unaffected county. With red tide predicted to increase in frequency and severity, mitigation of the effects must be paramount for these counties. Losses occur in almost all sectors of the economy, and for a state that relies so much on the health of the environment, declines in property values are a sign that action must be taken against these blooms.

The appearance of Karenia brevis red tides in the Gulf of Mexico have been studied widely in terms of its negative effects on marine life at various trophic levels. In this study, the long-term spatial and temporal patterns of Karenia brevis were analyzed along the western shelf of the Florida peninsula, where they were found to be primarily clustered. A variety of geospatial techniques were used to reveal the location dynamics of the presence of the algae. The spatial patterns of the blooms exhibited a predominantly northwest to southeast orientation along Florida’s western shelf. At the decadal scale, the spatial mean centers of the dinoflagellate were clustered along the western shelf from Tampa Bay to just south of the Caloosahatchee River Basin. In order to analyze the change in the spatial concentrations of Karenia brevis, we utilized Emerging Hot Spots Analysis. The results indicated the concentration of the bloom’s hotspots to be sporadic, meaning variable hotspots over the years, though not statistically significant. However, the results of Hot Spots Cold Spots analysis at the individual annual scale revealed the location of statistically significant hotspots along the western shelf with variable locations. In addition, we conducted all of the geospatial analysis at different depth categories. The results demonstrated substantial differences in the spatial and temporal patterns between the shallow (less than 6.831 m) and deep (greater than 6.831 m) depths. For instance, the shallow depth presence points were clustered in the Tampa Bay area, while the deep presence points were found in smaller clusters further north along Florida’s west coast. These results imply that underlying physical or biological factors are responsible for annual changes in bloom prevalence, such as the presence and origination of upwelling in the region. The presence of less frequent deep-ocean upwelling shifts nutrient acquisition in favor of faster growing phytoplankton like diatoms over slow growing dinoflagellates such as Karenia brevis, which require wind-driven upwelling to bolster blooms.

Nitric oxide (NO) is a non-traditional regulator of the growth of plants and phytoplankton. Here, the growth of five marine phytoplankton species, Platymonas helgolandica var. tsingtaoensis, Platymonas subcordiformis, Skeletonema costatum, Gymnodinium sp., and Prorocentrum donghaiense, was monitored, and carbonate system parameters in the culture media were determined after adding different concentrations of NO and sodium nitroprusside (SNP, NO donor) solutions. The two dietary algae (P. helgolandica var. tsingtaoensis and P. subcordiformis) and three red tide algae (S. costatum, Gymnodinium sp., and P. donghaiense) showed different responses to the same NO concentration. The red tide algae were more sensitive to exogenous NO than the dietary algae. NO with a concentration of 1.4 × 10−6 mol L−1 had the optimal stimulatory effect on the growth of the microalgae and increased the cell density by 9.8–38.3%. SNP solution with a concentration of 100 μmol L−1 inhibited the growth of the two dietary algae, and the cell density decreased by 38.8–84.3%. The addition of 10 μmol L−1 SNP solution to the three red tide algae decreased the cell density by 95.3–99.9%. Low concentrations of SNP (0.1 μmol L−1 for the two dietary algae and 0.01 μmol L−1 for the red tide algae) slightly promoted the growth of microalgae. High concentrations of NO (100 μmol L−1 SNP) inhibited CO2 assimilation, whereas low concentrations of NO (0.01–1.0 μmol L−1 SNP) promoted CO2 assimilation, indicating that NO participates in the regulation of photosynthesis.

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.

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

This paper examines the character of phytoplankton blooms in a restricted sub-tropical lagoon along the Atlantic coast of central Florida. The results of the 23-year study (1997–2020) provide evidence for multiple types of variability in bloom activity, including cyclical patterns, stochastic events, and most prominently a regime shift in composition and intensity. Cyclical patterns (e.g., El Niño/La Niña periods) and stochastic events (e.g., tropical storms) influenced rainfall levels, which in turn impacted nutrient concentrations in the water column and the timing and intensity of blooms. In 2011, a major change occurred in the character of blooms, with a dramatic increase in peak biomass levels of blooms and the appearance of new dominant taxa, including the brown tide speciesAureoumbra lagunensisand other nanoplanktonic species. Results of quantitative analyses reveal system behavior indicative of a regime shift. The shift coincided with widespread losses of seagrass community and reduced drift algae biomass. A combination of exceptionally low water temperatures in the winters of 2009/2010 and 2010/2011, hypersaline conditions associated with drought conditions, and high light attenuation caused by blooms appear to have contributed to the widespread and protracted decline in seagrass and drift macroalgal communities in the lagoon, leading to shifts in distribution of internal and external nutrient sources toward phytoplankton.

Knowledge of juvenile recruitment (defined here as the quantitative addition of early benthic life stages to a local population) is important for conserving heavily harvested species and their critical habitats. Stone crabs (genus Menippe) are commercially and ecologically important throughout the Gulf of Mexico nearshore waters off Florida, but very little is known about their recruitment. Using standard commercial stone crab traps, megalopal and postsettlement juvenile (collectively, young-of-the-year, “YOY”) stone crabs were sampled at multiple spatial scales and for multiple stone crab generations to characterize geographical, seasonal, and interannual variation in their distribution and relative abundance (numbers collected on traps) in the Gulf of Mexico off peninsular Florida and north of the Florida Keys (the “Florida Gulf”). The influences of potentially relevant oceanographic and biological variables [temperature, salinity, benthic community on the traps (trap fouling community), depth, distance from shore] on YOY stone crabs were investigated at locations distributed throughout the study area. Trap fouling communities had never been analyzed in detail prior to this study; an importance index was developed to quantify the seasonality, commonality, and density of the fouling communities and organisms composing the communities. Continuous, long-term data from the Tampa Bay location allowed investigation of the effects of biological relationships [relative abundance of female Menippe carrying eggs (ovigerous), occurrences of red tide (Karenia brevis, a toxic dinoflagellate) blooms] and meteorological events [tropical cyclones, El Nino Southern Oscillation (ENSO) occurrences] on temporal patterns of variation in recruitment. High relative abundances of YOY stone crabs were collected off peninsular Florida from dense, complex benthic biota that grew on crab traps located off large, pristine estuaries in relatively turbid water less than 5 m deep, where salinity ranged 24–36 and water temperature averaged 29°C–32°C. Two major recruitment locations, stable through decades, consistently accounted for approximately 50% of the YOY stone crabs collected; two secondary recruitment locations similarly accounted for another 25%. Relative abundance of YOY stone crabs was highest nearshore at the major recruitment locations, particularly during years of high relative abundance. Approximately 65%–75% of the recruits were collected August to October; however, the timing of both peak relative abundance and lowest relative abundance shifted to later in the year as latitude decreased. Patterns of change among months in relative abundance differed among locations within years and among years within locations. Water temperature, salinity, and trap fouling community were the important determinants of temporal and spatial variation in YOY stone crab relative abundance; depth and distance from shore were also important in areas where they varied notably among stations within locations and across broader expanses of the study area. At Tampa Bay, a sharp increase in relative abundance of ovigerous females in spring was followed by a similarly sharp increase in YOY stone crab relative abundance (principally stage 3–5 crabs) 3 mo later; whereas a sharp decrease in ovigerous female relative abundance in autumn was followed by a similarly sharp decrease in YOY stone crab relative abundance 1 mo later. Coincidence of the normal autumnal decrease in YOY stone crab relative abundance with red tides and tropical cyclones prevented assigning clear relationships between seasonal change in relative abundance and these potential external influences. Annual decreases in relative abundance were significantly related to the occurrence of tropical cyclones that came near Tampa Bay during the previous year. Twice, confluences of multiple hurricanes, timely red tides, and ENSO events were followed by nearly complete, 1- to 2-y recruitment collapses. In contrast, a single meteorologically and oceanographically highly anomalous year coincided with exceptionally high abundances of both YOY and ovigerous female stone crabs. A relationship between YOY stone crabs and subsequent fishery harvest was not evident, possibly due to a variety of fishery practices. Because stone crabs are subjected to intense fishing pressure throughout the Florida Gulf, the YOY stone crab recruitment grounds and their associated estuaries should be protected from the effects of development, agriculture, aquaculture, and commercial and recreational crabbing.

We investigated the health risks and benefits among surfers in Monterey Bay, Santa Cruz County, California, United States after seawater exposure. A total of 47 surfers enrolled and completed an online survey on the effect of the ocean environment on their well-being, physical and mental health, and provided their perspectives on ocean conservation. The majority of the surfers were white males, with a median age of 40 years, and a mean of 21 years surfing experience. Most of the participants spent over 5 h/week in the ocean. The most common health problems reported were adverse effects due to red tide exposure, surfer’s ear, back and neck problems, and allergies. A total of 41% reported upper respiratory symptoms, and 8% of the participants reported gastrointestinal symptoms. All participants reported that the ocean benefited their emotional health, and 45/47 (>96%) reported that the ocean increased their life satisfaction, happiness, and decreased their stress level. All participants reported being engaged in ocean stewardship. This study suggests surfers were significantly more likely to report upper respiratory symptoms when they had experienced adverse health effects while surfing during a “red tide” and during a bloom of the microscopic, single-celled phytoplankter,Akashiwo sanguinea.

Red tide blooms caused by the toxic dinoflagellate Karenia brevis are natural disturbance events that occur regularly along Florida’s west coast, often resulting in massive fish kills and marine mammal, seabird, and sea turtle mortalities. Limited prior work on the ecological effects of red tides suggests they play an important role in structuring ecosystem dynamics and regulating communities, however specific effects on prey populations and potential alterations to predator-prey interactions are unknown. We surveyed the prey fish assemblage of a top marine predator, the common bottlenose dolphin (Tursiops truncatus), in shallow seagrass habitat in Sarasota Bay, Florida, during 2004–2019, collecting data on prey density, species composition, K. brevis cell densities, and environmental variables. Across eight distinct red tide bloom events, resistance, resilience, and the ecological effects on the prey assemblage varied depending on bloom intensity, season, and frequency. Prey assemblage structure showed significant and distinct short-term shifts during blooms independent of the normal seasonal shifts in prey structure seen during non-bloom conditions. Canonical correspondence analysis indicated a strong influence of K. brevis density on assemblage structure. Blooms occurring primarily in the summer were associated with less initial prey resistance and higher than average annual catch per unit effort (CPUE) 1–3 years following bloom cessation, with bloom frequency prolonging the time needed to reach higher than average annual CPUE. Regardless of season, recovery to pre-bloom prey abundances occurred within 1 year. Sample-based rarefaction and extrapolation indicated significant differences in prey diversity among summer bloom events. This study is a first step in identifying differences in resistance, resilience, and the ecological effects of multiple red tide bloom events of various temporal scales and intensity on a dolphin prey assemblage. Improved understanding of the influence of red tides on estuarine structural dynamics and function can better inform management, and potentially guide mitigation efforts post-bloom.

Red tide is one of the most devastating phenomena that have impacted coastal environments and fishery on a local scale in the worldwide seas. Satellite imagery can provide a synoptic view of the re...

The nutrient regime has changed significantly in the Bohai Sea (BS) during the past six decades because of anthropogenic perturbations. Specifically, the concentration of DIN increased by about 7-fold from the end of the 1950s to the mid-2010s, while DIP and DSi concentrations decreased from the end of the 1950s to the beginning of the 1990s, and have since increased again. Unsynchronized changes in nutrient levels have led to changes in the nutrients structure, which has caused a series of ecological effects. Phytoplankton biomass increased by 6-fold from the 1960s to the mid-2010s. Additionally, phytoplankton composition shifted from a diatom-dominated to a dinoflagellate-dominated system, and the dominant species of macrozoobenthos changed. Red tides rarely occurred before the 1980s, but have occurred periodically and frequently since the 1990s. Finally, the BS ecosystem has shifted from an N-limited oligotrophic state before the 1990s to a potentially P-limited eutrophic state.