Confirmation of AETX production's genetic potential employed the amplification of three distinct loci within the AETX gene cluster, supplemented by the amplification of two variable rRNA ITS regions, ensuring consistent taxonomic identity among the producers. PCR analysis of four loci in Hydrilla samples from three Aetokthonos-positive reservoirs and one Aetokthonos-negative lake demonstrated findings congruent with the microscopic observation of Aetokthonos, both through light and fluorescence microscopy. The Aetokthonos-positive samples exhibited AETX production, as corroborated by LC-MS. In the J. Strom Thurmond Reservoir, devoid of Hydrilla, a cyanobacterium resembling Aetokthonos was intriguingly observed growing on American water-willow (Justicia americana). While all three aet markers were present in the specimens, the quantity of AETX was exceptionally small. The Aetokthonos, a newly discovered species, exhibits distinct morphology and genetic characteristics (ITS rRNA sequence) that differentiate it from the Hydrilla-hosted A. hydrillicola, possibly at the species level. Invasion biology Our investigation of the toxigenic Aetokthonos species yielded significant results. While capable of colonizing a wider variety of aquatic plants, the toxin accumulation level might depend on host-specific interactions, for example, the locally high bromide concentration in Hydrilla.

This research explored the causal elements behind the occurrences of Pseudo-nitzschia seriata and Pseudo-nitzschia delicatissima blooms in the eastern English Channel and southern North Sea. A multivariate statistical analysis, employing Hutchinson's niche concept, was applied to the phytoplankton data series spanning 1992 to 2020. P. seriata and P. delicatissima complex presence was observed continually, but their blooming periods varied considerably because of their different realized ecological niches. The ecological niche of the P. delicatissima complex was less favorable and characterized by a lower tolerance level in comparison to the P. seriata complex. The P. delicatissima complex, often blooming from April to May, coincided with the presence of Phaeocystis globosa, whereas the P. seriata complex more commonly bloomed in June, occurring during the waning stages of less intense P. globosa blooms. Both P. delicatissima and P. seriata complexes prospered in environments characterized by low silicate levels and minimal water movement, yet their sensitivity to water temperature, light intensity, ammonium, phosphate, and the combined nitrite and nitrate load differed. The occurrences of P. delicatissima and P. seriata blooms were notably impacted by shifts in niche spaces and the effects of biotic interactions. Sub-niches differed for the two complexes, depending on whether they were in a state of low abundance or bloom. There were differences in the phytoplankton community structure and the quantity of other taxa whose niches mirrored those of P. delicatissima and P. seriata across these periods. The community structure's variations were predominantly driven by the P. globosa taxon. P. delicatissima complex displayed a positive interaction with P. globosa, whereas P. seriata complex showed a negative interaction with P. globosa.

Phytoplankton forming harmful algal blooms (HABs) can be monitored using three approaches: light microscopy, FlowCam, and the sandwich hybridization assay (SHA). However, these techniques have not been evaluated comparatively. This study addressed the knowledge gap through research on the saxitoxin-producing 'red tide' dinoflagellate Alexandrium catenella, a species infamous for causing blooms and the global phenomenon of paralytic shellfish poisoning. Employing A. catenella cultures at varying stages—low (pre-bloom), moderate (bloom), and high (dense bloom)—the dynamic ranges of each technique were contrasted. Field detection was evaluated by analyzing water samples that had a very low concentration of the substance (0.005) for each treatment. Findings relevant to HAB researchers, managers, and public health officials result from reconciling conflicting cell abundance datasets, thereby strengthening numerical models and bolstering the accuracy of HAB monitoring and prediction. In addition, the results likely apply generally to a diverse selection of HAB species.

The composition of phytoplankton has a significant impact on the physiological biochemical attributes and growth of filter-feeding bivalves. As dinoflagellate biomass and blooms escalate in mariculture areas, the consequences of their presence, especially at non-lethal levels, on the physio-biochemical traits and the quality of mariculture organisms, are not fully elucidated. Two Karlodinium species, K. veneficum (KV) and K. zhouanum (KZ), possessing different densities, were mixed with high-quality Isochrysis galbana microalgae and used to feed Manila clams (Ruditapes philippinarum) in a 14-day temporary culture setup. This experiment aimed to comparatively assess the impact on the critical biochemical metabolites, such as glycogen, free amino acids (FAAs), fatty acids (FAs), and volatile organic compounds (VOCs), within the clams. Species-specific dinoflagellate populations and their densities were directly linked to the survival rates of the clams. The high-density KV treatment group exhibited a 32% lower survival rate than the pure I. galbana control, whereas KZ, at low concentrations, did not influence survival relative to the control group. The high-density KV group saw a decrease in glycogen and fatty acid concentrations (p < 0.005), thus implying a marked influence on energy and protein metabolic activities. The dinoflagellate-mixed groups demonstrated the presence of carnosine, with a range of 4991 1464 to 8474 859 g/g of muscle wet weight, while the field samples and pure I. galbana control lacked this compound. This observation implicates carnosine in the clam's anti-stress response to dinoflagellate exposure. The fatty acid makeup across the different groups did not show substantial divergence. The high-density KV group showed a significant decrease in endogenous C18 PUFA precursors, linoleic acid and α-linolenic acid, compared to the other groups, which signifies that high KV density impacts fatty acid metabolism. Clams exposed to dinoflagellates, as reflected in changes to the VOC profile, may experience oxidation of fatty acids and degradation of free amino acids as a consequence. Clam exposure to dinoflagellates possibly triggered an increase in VOCs, such as aldehydes, and a decrease in 1-octen-3-ol, leading to a more pungent fishy flavor and a compromised overall quality of the food. The clam's biochemical metabolism and seafood quality were observed to be altered in this present study. KZ feed, displaying a moderate density, exhibited positive implications for aquaculture yields, enhancing the production of carnosine, a substance highly valued for its various bioactivities.

Red tide succession is heavily reliant on the interplay of temperature and light intensity. However, the question of differing molecular mechanisms across various species is still unresolved. This investigation determined the changes in growth, pigment, and transcriptional measurements of two bloom-forming dinoflagellates, Prorocentrum micans and P. cordatum. CVN293 mw A 7-day batch culture was performed across four treatments, each representing a unique combination of two temperatures (20°C low, 28°C high) and two light intensities (50 mol photons m⁻² s⁻¹ low, 400 mol photons m⁻² s⁻¹ high). The fastest growth was unequivocally associated with high temperature and high light (HTHL) conditions, while the slowest growth was evident under high temperature and low light (HTLL) conditions. The concentrations of chlorophyll a and carotenoid pigments decreased considerably in every high-light (HL) experimental group, yet remained unchanged in the high-temperature (HT) treatments. HL acted to alleviate the photolimitation caused by insufficient light, thereby enhancing the growth of both species within low temperature conditions. However, HT's effect on both species' growth was detrimental, manifesting as oxidative stress triggered by low light conditions. HL's countermeasure to the growth stress caused by HT in both species involved an increase in photosynthetic capacity, enhancement of antioxidant defenses, promotion of protein folding, and acceleration of protein degradation. The cells of P. micans exhibited a greater degree of sensitivity to HT and HL than did the cells of P. cordatum. The investigation into dinoflagellates' species-specific transcriptomic adaptations, conducted in this study, contributes significantly to our knowledge base, anticipating future oceanic shifts, including higher solar irradiance and elevated temperatures within the upper mixed layer.

Lakes across Washington experienced the presence of Woronichinia, as indicated by monitoring data collected from 2007 through 2019. Within the cyanobacterial blooms occurring in the wet temperate zone west of the Cascade Mountains, this cyanobacterium was typically either the main or a supporting species. Woronichinia was often found with Microcystis, Dolichospermum, and Aphanizomenon flos-aquae in these lakes, where the cyanotoxin microcystin was often observed. Whether or not Woronichinia itself generated this toxin, though, was previously unknown. The initial full genome of Woronichinia naegeliana WA131, a newly sequenced genome, is reported here, assembled from a metagenome sample from Wiser Lake, Washington, collected in 2018. Medicine traditional The genome lacks genes for cyanotoxin production or taste-and-odor compounds, yet it does contain biosynthetic gene clusters for other bioactive peptides, including anabaenopeptins, cyanopeptolins, microginins, and ribosomally produced, post-translationally modified peptides. Photosynthesis, nutrient acquisition, vitamin synthesis, and buoyancy genes are characteristic of bloom-forming cyanobacteria, despite the notable absence of nitrate and nitrite reductase genes.