Spatiotemporal distribution characteristics of yessotoxins and pectenotoxins in phytoplankton and shellfish collected from the southern coast of South Korea

First investigation of the temporal distribution of neurotoxin β-N-methylamino-L-alanine (BMAA) and the candidate causative microalgae along the South Sea Coast of Korea

The neurotoxin β-N-methylamino-L-alanine (BMAA), produced by cyanobacteria and diatoms, has been implicated as an environmental risk factor for neurodegenerative diseases. This study first investigated the occurrence and monthly distributions of BMAA and its isomers, 2,4-diaminobutyric acid (DAB) and N-2-aminoethylglycine (AEG), in phytoplankton and mussels from 11 sites along the South Sea Coast of Korea throughout 2021. These toxins were quantified using LC-MS/MS, revealing elevated BMAA concentrations from late autumn to spring, with phase lags observed between phytoplankton and mussels. The highest concentration of BMAA in phytoplankton was detected in November (mean: 1490 ng g-1 dry weight (dw)), while in mussels, it peaked in December (mean: 1240 ng g-1 dw). DAB was detected in phytoplankton but was absent in mussels, indicating limited bioaccumulation potential. In February, the peak mean DAB concentration in phytoplankton was 89 ng g-1 dw. AEG was not detected in any samples. Chlorophyll-a concentrations consistently showed an inverse correlation with BMAA concentrations in mussels throughout the year. Through correlation analysis, four diatom genera, Bacillaria, Hemiaulus, Odontella, and Pleurosigma, were identified as potential causative microalgae of BMAA. This study offers insights into identifying the causative microalgae for BMAA and informs future regulatory efforts regarding unmanaged biotoxins.

Nationwide seasonal monitoring of lipophilic marine algal toxins in shellfish and causative microalgae along the coasts of South Korea

In this study, lipophilic marine algal toxins (LMATs)-producing microalgae were identified at 23 sites along the coasts of Korea, and distribution characteristics of LMATs in phytoplankton and mussels were investigated. The causative microalgae, including Gonyaulux spinifera, Dinophysis acuminata, D. caudata, and D. fortii, were observed in the study area, with notably higher densities during the summer. Significant correlations were found between the densities of these microalgae and the water temperature. Seasonal distribution patterns of LMATs in phytoplankton closely matched those observed in mussels. Notably, LMAT concentrations in mussels from the Yellow Sea were relatively high. PTX2 was detected predominantly in phytoplankton, and homo-yessotoxin was found mainly in mussels. Overall, LMAT concentrations were elevated in the summer, raising concerns about biotoxin contamination in shellfish. These results provide important insights into the dynamics of unmanaged marine biotoxins in Korea and offer baseline data for future safety management policies and inflow surveillance.

The Prevalence of Marine Lipophilic Phycotoxins Causes Potential Risks in a Tropical Small Island Developing State

Tropical small island developing states (SIDS), with their geographical isolation and limited resources, heavily rely on the fisheries industry for food and revenue. The presence of marine lipophilic phycotoxins (MLPs) poses risks to their economy and human health. To understand the contamination status and potential risks, the Republic of Kiribati was selected as the representative tropical SIDS and 55 species of 256 coral reef fish encompassing multiple trophic levels and feeding strategies were collected to analyze 17 typical MLPs. Our results showed that the potential risks of ciguatoxins were the highest and approximately 62% of fish species may pose risks for consumers. Biomagnification of ciguatoxins was observed in the food web with a trophic magnification factor of 2.90. Brevetoxin-3, okadaic acid, and dinophysistoxin-1 and -2 were first reported, but the risks posed by okadaic acid and dinophysistoxins were found to be negligible. The correlation analysis revealed that fish body size and trophic position are unreliable metrics to indicate the associated risks and prevent the consumption of contaminated fish. The potential risks of MLPs in Kiribati are of concern, and our findings can serve as valuable inputs for developing food safety policies and fisheries management strategies specific to tropical SIDS contexts.

Using solid phase adsorption toxin tracking and extended local similarity analysis to monitor lipophilic shellfish toxins in a mussel culture ranch in the Yangtze River Estuary

Harmful algal blooms (HABs) and their associated phycotoxins are increasing globally, posing great threats to local coastal ecosystems and human health. Nutrients have been carried by the freshwater Yangtze River and have entered the estuary, which was reported to be a biodiversity-rich but HAB-frequent region. Here, in situ solid phase adsorption toxin tracking (SPATT) was used to monitor lipophilic shellfish toxins (LSTs) in seawaters, and extended local similarity analysis (eLSA) was conducted to trace the temporal and special regions of those LSTs in a one-year trail in a mussel culture ranch in the Yangtze River Estuary. Nine analogs of LSTs, including okadaic acid (OA), dinophysistoxin-1 (DTX1), yessotoxin (YTX), homoyessotoxin (homoYTX), 45-OH-homoYTX, pectenotoxin-2 (PTX2), 7-epi-PTX2 seco acid (7-epi-PTX2sa), gymnodimine (GYM) and azaspiracids-3 (AZA3), were detected in seawater (SPATT) or rope farmed mussels. The concentrations of OA + DTX1 and homoYTX in mussels were positively correlated with those in SPATT samplers (Pearson test, p < 0.05), indicating that SPATT (with resin HP20) would be a good monitoring tool and potential indicator for OA + DTX1 and homoYTX in mussel Mytilus coruscus. The eLSA results indicated that late summer and early autumn were the most phycotoxin-contaminated seasons in the Yangtze River Estuary. OA + DTX1, homoYTX, PTX2 and GYM were most likely driven by the local growing HAB species in spring and summer, while Yangtze River diluted water may impact the accumulation of HAB species, causing potential phycotoxin contamination in the Yangtze River Estuary in autumn and winter. Together, the results showed that the mussel harvesting season, late summer and early autumn, would be the season with the greatest phycotoxin risk and would be the most contaminated by local growing toxic algae. Routine monitoring sites should be set up close to the local seawaters.

Sustainable bioremediation technologies for algal toxins and their ecological significance

The emergence of algal toxins in water ecosystems poses a significant ecological and human health concern. These toxins, produced by various algal species, can lead to harmful algal blooms, and have far-reaching consequences on biodiversity, food chains, and water quality. This review explores the types and sources of algal toxins, their ecological impacts, and the associated human health risks. Additionally, the review delves into the potential of bioremediation strategies to mitigate the effects of algal toxins. It discusses the role of microorganisms, enzymes, and algal-bacterial interactions in toxin removal, along with engineering approaches such as advanced oxidation processes and adsorbent utilization. Microbes and enzymes have been studied for their environmentally friendly and biocompatible properties, which make them useful for controlling or removing harmful algae and their toxins. The challenges and limitations of bioremediation are examined, along with case studies highlighting successful toxin control efforts. Finally, the review outlines future prospects, emerging technologies, and the need for continued research to effectively address the complex issue of algal toxins and their ecological significance.

Monthly distribution of lipophilic marine biotoxins and associated microalgae in the South Sea Coast of Korea throughout 2021

Aquaculture farms have been established along the South Sea Coast of Korea, supplying most of the seafood consumed domestically. However, annual harmful algal blooms pose a potential threat to seafood safety. This study aimed to determine the spatial and seasonal distributions of 12 lipophilic marine biotoxins (LMTs) in phytoplankton and mussels in the region in 2021. Solid-phase adsorption toxin tracking (SPATT) was used to monitor the cumulative compositions of LMTs in seawater. LMT concentrations were also determined in twelve commercially available species of domestic shellfish to evaluate the potential risks to human health. Gonyaulux spinifera and Dinophysis acuminata, causative microalgae of yessotoxins (YTXs) and pectenotoxins (PTXs), respectively, showed high densities in the region from May to July. This period corresponded to high LMT concentrations in phytoplankton and mussels. Phytoplankton mainly contained PTX-2 and homo-YTX, with a maximum concentration of 2300 ng g-1 wet weight (ww) in May. In contrast, mussels mainly contained homo-YTX and YTX, with a maximum concentration of 1300 ng g-1 ww in July. LMTs-producing microalgae showed low densities and concentrations after July, whereas mussels accumulated toxins until September. In the SPATT sampler, more diverse LMTs were detected than in seawater, phytoplankton, and mussels. For example, dinophysistoxin-1 and azaspiracid-2 were detected only in SPATT. YTXs were detected in domestic seafood samples, including mussels, red scallops, and pen shells, but the concentrations were below the European Food Safety Agency recommended standard of 3.75 mg YTX-eq. kg-1. Moreover, the hazard quotient was less than 100 in all scenarios, indicating that the human health risk was not significant. This study provides valuable data on monthly distribution patterns of LMTs in the South Sea Coast of Korea and can serve as baseline data for future management policies of marine biotoxins.