Hamamelis Research Articles

Tracking the Spatio-Temporal Distribution of Organic Particles to Predict Macroaggregation in the Northern Adriatic Sea

In the last two decades, the phenomenon of macroaggregation has become more frequent in the Mediterranean Sea and beyond, but it has disappeared in the northern Adriatic. The aim of this study was to present, for the first time, the concentration of surface-active particles (SAP) at selected sampling stations in the northern Adriatic Sea, as well as phytoplankton and chlorophyll data and physical properties of seawater, in order to investigate the role of SAP in macroaggregation. We used an electrochemical method (polarography and amperometry) to directly and throughput characterize fragile organic material in terms of its dissolved and particulate state in seawater samples. The results show that the concentration of SAP is subject to seasonal variations and was generally higher in the western region. In addition, an increase in surfactant activity and concentration of SAP was detected in the subsurface layer and in the stratified column prior to the mucilage event, which may be related to the very high abundance of Skeletonema marinoi, a diatom characteristic of the winter bloom in the region. We noted an order of magnitude higher concentration of SAP than typically observed in late winter/early spring, which serves as a precursor to the macroaggregation that occurs under certain environmental and oceanographic conditions in marine systems.

Ginnalin A and hamamelitannin: the unique gallotannins with promising anti-carcinogenic potential.

Tannins are secondary metabolites that belong to the family of polyphenolic compounds and have gained a huge interest among researchers due to their versatile therapeutic potential. After lignin, these are the second most abundant polyphenols found in almost every plant part like stem, bark, fruit, seed, leaves, etc. Depending upon their structural composition, these polyphenols can be divided into two distinct groups, namely condensed tannins and hydrolysable tannins. Hydrolysable tannins can be further divided into two types: gallotannins and ellagitannins. Gallotannins are formed by the esterification of D-glucose hydroxyl groups with gallic acid. The gallolyl moieties are bound by a depside bond. The current review focuses mainly on the anti-carcinogenic potential of recently discovered gallotannins, ginnalin A, and hamamelitannin (HAM). Both of these gallotannins possess two galloyl moieties linked to a core monosaccharide having anti-oxidant, anti-inflammatory, and anti-carcinogenic abilities. Ginnalin A is found in plants of the genus Acer whereas HAM is present in witch hazel plants. The biosynthetic pathway of ginnalin A along with the mechanism of the anti-cancer therapeutic potential of ginnalin A and HAM has been discussed. This review will certainly help researchers to work further on the chemo-therapeutic abilities of these two unique gallotannins.

Mesozooplankton size structure in the Canary Current System

Changes in plankton composition influences the dynamics of marine food webs and carbon sinking rates. Understanding the core structure and function of the plankton distribution is of paramount importance to know their role in trophic transfer and efficiency. Here, we studied the zooplankton distribution, abundance, composition, and size spectra for the characterization of the community under different oceanographic conditions in the Canaries-African Transition Zone (C-ATZ). This region is a transition zone between the coastal upwelling and the open ocean showing a high variability because of the physical, chemical, and biological changes between eutrophic and oligotrophic conditions through the annual cycle. During the late winter bloom (LWB), chlorophyll a and primary production were higher compared to that of the stratified season (SS), especially in the upwelling influenced area. Abundance distribution analysis clustered stations into two main groups according to the season (productive versus stratified season), and one group sampled in the upwelling influenced area. Size-spectra analysis showed steeper slopes during daytime in the SS, suggesting a less structured community and a higher trophic efficiency during the LWB due to the favorable oceanographic conditions. We also observed a significant difference between day and nighttime size spectra due to community change during diel vertical migration. Cladocera were the key taxa differentiating an Upwelling-group, from a LWB- and SS-group. These two latter groups were differentiated by Salpidae and Appendicularia mainly. Data obtained in this study suggested that abundance composition might be useful when describing community taxonomic changes, while size-spectra gives an idea of the ecosystem structure, predatory interactions with higher trophic levels and shifts in size structure.

The Importance of Winter Dinoflagellate Blooms in Chesapeake Bay—a Missing Link in Bay Productivity

It is widely assumed that phytoplankton abundance and productivity decline during temperate winters because of low irradiance and temperatures. However, winter phytoplankton blooms commonly occur in temperate estuaries, but they are often undocumented because of reduced water quality monitoring in winter. The small body of in situ work that has been done on winter blooms suggests they can be of enormous consequence to ecosystems. However, because monitoring is often reduced or stopped altogether during winter, it is unclear how widespread these blooms are or how long they can last. We analyzed an over 30-year record of monthly phytoplankton monitoring samples along with ad hoc sampling throughout Chesapeake Bay to assess the distributions of two common winter bloom species, Heterocapsa rotundata and Heterocapsa steinii, and the environmental conditions associated with these blooms. The long-term monitoring data revealed that H. rotundata blooms occur within a narrow salinity range (7–12) and potentially have different triggers depending upon the nutrient status of waters affected. The ad hoc sampling confirmed the occurrence of H. steinii blooms in the lower Chesapeake Bay, despite the lack of evidence for them from monthly monitoring data. Together, our findings demonstrate that winter blooms routinely occur in numerous locations throughout Chesapeake Bay and can last up to a month. Our findings suggest that while winter blooms are a staple of the Bay’s annual phytoplankton community, there are major data gaps reporting their occurrence highlighting the need for more frequent monitoring to understand factors promoting these blooms and their consequences on ecosystem productivity.

Anomalous thermal and winds condition drove low surface chlorophyll-a in La Paz Bay during the 2015–2016 El Niño event

La Paz Bay (LPB) considered one of the most highly productive bays in the southwestern Gulf of California, Mexico, recently established as Priority Marine Region, supports many species of ecological importance. In this context, daily composites of surface chlorophyll a (Chl-aSAT), sea surface temperature (SST) satellite images derived from the MODIS-Aqua sensor, and a wind intensity index (WI) calculated with data recorded simultaneously at four points along the coast, were used to describe the strong 2015–2016 El Niño impact over the surface chlorophyll pigments in LPB, relative to its average for 2003–2013. Significant relationships between SST, WI (used as environmental factors) and Chl-aSAT (RSST = −0.74, RWI = −0.40, P < 0.01) were found using exponential models for the entire study period, with moderate correlation during El Niño winter condition (December 2015 to March 2016) between SST and Chl-aSAT (RSST = 0.45, P < 0.02). The Chl-aSAT showed unexpectedly low values (∼0.5–1.2 mg m−3) with one month-lag of the winter bloom period jointly with the presence of warmer-than-usual water (∼1.0 °C) and episodes of strong northwesterly winds (speed 8.0–10.0 m s−1) that began in autumn that drove a ∼2 month-lag in its winter peak. The Chl-aSAT and SST winter spatial patterns, showed low Chl-aSAT values (∼−0.5 to −1.0 mg m−3) along the bay and higher-than-usual SST by ∼ 0.5–1.0 °C relative to a year under the La Niña winter condition (2017–2018). This triggered the possible thermocline deepening and the lowest levels of nutrient supply to the photic layer during the El Niño winter episode. Hovmöller diagrams of Chl-aSAT and SST anomalies along the coast revealed a sharp drop to negative anomaly values (∼− 0.7 to −1.2 mg m−3), in-phase but negatively correlated with the SST coastal anomalies (R = − 0.88, P < 0.01). This biophysical coupling played a crucial role in the exceptional drop to the lowest winter Chl-aSAT levels seen in LPB since the MODIS satellite sensor began taking measurements in 2002 (Chl-aSAT values were lower than usual by ∼ 0.9–1.2 mg m −3). Besides the lowest winter levels observed, this research reflected the El Niño signal-driven changes over the basic seasonal average of the LPB climate system The non-significant negative trend observed in the winter average Chl-aSAT values, indicates that LPB may be less resilient to future environmental disturbances.

Patient perspectives of wound care management in hidradenitis suppurativa.

Wound care management and costs in hidradenitis suppurativa (HS) are unmet needs. This study explored patient perspectives of at-home management of acute flares of HS and chronic daily wounds, their satisfaction with current wound care methods, and the financial burden of wound care supplies. An anonymous, multiple choice, cross-sectional questionnaire was distributed among online HS-related forums between August and October 2022. Participants 18years or older with a diagnosis of HS who live in the United States were included. In total, 302 participants completed the questionnaire: 168 White (55.6%), 76 Black (25.2%), 33 Hispanic (10.9%), 7 Asian (2.3%), 12 multiracial (4.0%), and 6 other (2.0%). Dressings commonly reported included gauze, panty liners or menstrual pads, tissues or toilet paper, antiseptic dressing, abdominal pads, and adhesive bandages. Commonly reported topical remedies for acute flares of HS included warm compresses, Epsom salt baths, Vicks VapoRub, tea tree oil, witch hazel, and bleach baths. One-third of participants (n = 102) reported dissatisfaction with current wound care methods, and 48.8% (n = 103) believed that their dermatologist does not meet their wound care needs. Nearly half (n = 135) reported being unable to afford the type and quantity of dressings and wound care supplies they would ideally want. Black participants were more likely than White participants to report being unable to afford their dressings and find the cost as very burdensome. Overall, dermatologists must improve patient education of wound care methods in HS and address the financial burden of wound care supplies by exploring insurance-funded options.

Winter Bloom of Marine Cyanobacterium, Trichodesmium erythraeum and Its Relation to Environmental Factors

A winter bloom event of Trichodesmium erythraeum was monitored for the first time in the southeastern coastal parts of Bangladesh along the Bay of Bengal. This study presents the brownish to light pinkish bloom that appeared in mid-winter and disappeared abruptly during spring. Heavy blooms of T. erythraeum revealed the highest concentration of 91.47 ± 52.94 × 103 colonies/L in the Bakkhali River Estuary, and 66.93 ± 12.95 × 103 colonies/L in the Maheshkhali Channel of the Bay of Bengal. Three distinct morphological shapes, namely puffs, tufts and asymmetrical colonies, were depicted as major types. Several environmental factors, such as water temperature, salinity, pH, dissolved oxygen, NO3–N and PO4–P, were analyzed to determine their relationship with the occurrence, abundance and bloom formation of T. erythraeum. The abundance of the species showed a positive correlation with salinity and pH while exhibiting a negative correlation with temperature and DO. A cluster analysis revealed a clear indication of T. erythraeum bloom during winter. Thus, the prevalence of the highest density of the bloom in the present study area strongly suggests increased monitoring and research efforts in order to effectively manage or impede harmful algal blooms.

Discovery of the bicycle gene family provides new insights into insect manipulation of plant development during gall induction.

Galls are complex structures that develop from plant tissue, providing protection and food for gall-forming organisms, such as insects or mites. However, the molecules used by insects or mites to manipulate plant development have proved elusive. A landmark study has tracked down a gene in a gall-forming aphid that controls whether galls on witch hazel are green or red. The 'green allele' is strongly expressed in aphid salivary glands and represses plant genes used for red color formation. Excitingly, the gene product is part of a large suite of proteins that aphids may use to interact with plant biology.

Development and characterization of bacterial cellulose membrane incorporated with Witch hazel extract

Development and characterization of bacterial cellulose membrane incorporated with Witch hazel extract

London Plane Tree Pollen and Pla A 1 Allergen Concentrations Assessment in Urban Environments

The London plane tree is frequently used in gardens, parks, and avenues in European urban areas for ornamental purposes with the aim to provide shade, and given its tolerance to atmospheric pollution. Nevertheless, unfortunately, over recent decades, bioaerosols such as Platanus pollen grains cause increasing human health problems such as allergies or respiratory tract infections. An aerobiological sampling of airborne Platanus pollen and Pla a 1 allergen was performed using two volumetric traps placed on the roof of the Science Faculty building of the city of Ourense from 2009 to 2020. A volumetric sampler Hirst–type Lanzoni VPPS 2000 (Lanzoni s.r.l. Bologna, Italy) was used for pollen sampling. Pla a 1 aeroallergen was sampled by using a Burkard Multi-Vial Cyclone Sampler (Burkard Manufacturing Co., Ltd., Hertfordshire, UK) and by means of the enzyme-linked immunosorbent assay (ELISA) technique. Data mining algorithms, C5.0 decision trees, and rule-based models were assessed to evaluate the effects of the main meteorological factors in the pollen or allergen concentrations. Plane trees bloom in late winter and spring months in the Northwestern Spain area. Regarding the trends of the parameters that define the Platanus pollen season, the allergen values fitted the concentrations of pollen in the air in most cases. In addition, it was observed that a decrease in maximum temperatures causes a descent in both pollen and allergen concentrations. However, the presence of precipitations only increases the level of allergens. When the risk of allergy symptomatology was jointly assessed for both the concentration of pollen and allergens in the study area, the number of days with moderate and high risk for pollen allergy in sensitive people increased with respect to traditional alerts considering only the pollen values.

Composition and genetic diversity of picoeukaryotes in the northeastern South China Sea during the Luzon winter bloom

We analyzed picoeukaryotes during the Luzon winter bloom, in combination with remote sensing, flow cytometry and high throughput sequencing. Satellite images showed a seasonal increase in phytoplankton in the study area during winter, and the in situ campaign observed an extremely high abundance of photosynthetic picoeukaryotes, which were the main contributors to the total phytoplankton biomass. Auto- and mixotrophic picoalgae (Chlorophyta, Ochrophyta, and Dinophyta), heterotrophic flagellates (Radiolaria) and parasites (Syndiniale) were found to be potentially numerous components of picoeukaryote communities. Overall, auto- and mixotrophic photosynthetic picoeukaryotes were mainly distributed in the upper layers (0–100 m) while heterotrophic flagellates and parasites dominated the deep layers (200–300 m). The Kuroshio-induced upwelling stimulated the growth of photosynthetic picoeukaryotes, which mainly belonged to Chlorophyta, especially the class Mamiellophyceae.

The effectiveness of using a homeopathic preparation containing calendula, witch hazel, aesculus, menthol and zinc oxide in patients with nasal obstruction in vasomotor and chronic subatrophic rhinitis

Introduction. In recent years, the world has seen an increase in the number of patients with difficulty in nasal breathing due to nasal obstruction, one of the causes of which are functional disorders of the nasal mucosa in various forms of rhinitis. Frequent use of intranasal decongestants among the population further contributes to the lack of effectiveness of conservative treatment and the need for surgical correction to restore free nasal breathing. This article discusses the possibility of using a homeopathic preparation containing calendula, witch hazel, aesculus, menthol and zinc oxide in patients with nasal obstruction in vasomotor and chronic subatrophic rhinitis to stop the clinical manifestations of the disease and improve the quality of life of patients. Аim. Тo evaluate the effectiveness of a drug containing calendula, witch hazel, aesculus, menthol and zinc oxide in patients with vasomotor and chronic subatrophic rhinitis in the complex treatment of nasal obstruction. Мaterials and methods. The study involved 48 adult patients of both sexes, aged 20 to 50 years, diagnosed with vasomotor (idiopathic) rhinitis in 24 and chronic subatrophic rhinitis in 24 patients. The studied preparation containing calendula, witch hazel, esculus, menthol and zinc oxide was smeared on the mucous membrane of the nasal cavity by laying gauze turundas for 5 minutes, 3 times a day, while the course of treatment was 10 days. The efficacy and safety of the drug was assessed by the dynamics of the severity of subjective symptoms, objective clinical data during control examinations by an otorhinolaryngologist in points, as well as by the presence of side effects in the treatment of the disease. Results. Results of the study showed a pronounced positive trend in the form of relief of subjective complaints and the main clinical manifestations of the disease, accompanied by an improvement in the quality of life in patients in both groups examined during treatment. Side effects were not observed in patients in both study groups. Conclusions. Based on the results of the study, conclusions were drawn about the efficacy and safety of using a complex homeopathic preparation containing calendula, witch hazel, esculus, menthol and zinc oxide in an adult group of patients with nasal obstruction, which makes it possible to recommend it for widespread use for the complex treatment of nasal syndrome. obstruction in vasomotor and chronic subatrophic rhinitis, as well as other forms of rhinitis accompanied by nasal obstruction syndrome.

Flow cytometry as an alternative method to evaluate genotoxicity of natural cosmetic actives.

To suggest the expansion of the use of in vitro safety techniques recommended by the OECD guidelines and to propose the use of the automation of the in vitro mammalian micronucleus test method by flow cytometry to assess the genotoxic potential of Centella asiatica, Horse Chestnut, Witch Hazel, Blend, Ecoblend, and Caffeine extracts due to their widespread use in commercial products. Flow cytometer analysis was performed using the Accuri™ C6 equipment and analyzed using the FlowJo software. Cytotoxicity tests followed OECD 129 guidelines and Phototoxicity followed OECD/GD 432 guidelines. The results showed that the cytotoxicity assay presented a decrease in cell viability when cells were exposed to Centella asiatica from a concentration of 5.0%, horse chestnut 2.5%, Witch hazel 2.5%, Blend 3.13%, and Caffeine 3%, while Ecoblend at the tested concentrations did not show cytotoxicity. In the phototoxicity test, the samples at the tested concentrations showed a PIF <2 being considered potentially non-phototoxic. Finally, in the genotoxicity automated assay, samples were considered potentially non-genotoxic. In vitro methods are of paramount importance for the development of pre-clinical tests and the use of test automation helps to reduce the time for analysis and dissemination of results, being a determining factor for the prospect of new compounds.

Unravelling the roles of Indian Ocean Dipole and El-Niño on winter primary productivity over the Arabian Sea

The Northern Arabian Sea (NAS) is a highly productive basin in the Indian Ocean. The marked seasonal variation of surface winds has the major control on the oceanic primary productivity in the NAS. A regional physical and biogeochemical coupled model was used to examine the control of marine physical processes on the primary productivity in the NAS. It is found that the pure positive Indian Ocean Dipole (PPIOD) has positive anomalies, whereas a co-occurrence of El-Niño and positive IOD (CEPIOD) events leads to negative anomalies in winter-time Chlorophyll-a (Chl-a) concentration during 2000–2018. The CEPIOD events are characterized by weaker winter convective mixing than PPIOD events. The evolution of this discrepancy in the convective mixing process is sufficiently explained by the presence of weaker northeasterly (dry and cold) winds (<2.4 m/s) and a lower net heat flux loss (<- 47 W/m2) during CEPIOD as compared to the PPIOD events. Higher convective mixing results in intense convective cooling, a deeper mixed layer depth (MLD), increased nutrients’ injection through entrainment, and a stronger winter bloom, whereas weak convective mixing causes warming and a shallow MLD, resulting in weak winter bloom. The higher-mixing and surface-cooling condition was observed more often in PPIOD than in CEPIOD years. These conditions promote vertical convective mixing that maintains nutrients’ supply in the near-surface layers and supports primary productivity in PPIOD years.

The miR156-Targeted SQUAMOSA PROMOTER BINDING PROTEIN (PmSBP) Transcription Factor Regulates the Flowering Time by Binding to the Promoter of SUPPRESSOR OF OVEREXPRESSION OF CO1 (PmSOC1) in Prunus mume.

Prunus mume, a famous perennial ornamental plant and fruit tree in Asia, blooms in winter or early spring in the Yangtze River area. The flowering time directly determines its ornamental and economic value, so it is of great significance to study the molecular mechanism of flowering time. SQUAMOSA PROMOTER BINDING PROTEIN (SBP), often regulated by miR156, is an important flowering regulator, although its function is unknown in P. mume. Here, 11 miR156 precursors were analyzed and located in five chromosomes of the P. mume genome. The expression pattern showed that PmSBP1/6 was negatively correlated with miR156. The promoters of PmSBP1/6 were specifically expressed in the apical meristem. Overexpression of PmSBP1/6 in tobacco promoted flowering and changed the length ratio of pistil and stamen. Moreover, PmSBP1 also affected the number and vitality of pollen and reduced the fertility of transgenic tobacco. Furthermore, ectopic expression of PmSBP1/6 caused up-regulated expression of endogenous SUPPRESSOR OF OVEREXPRESSION OF CO1 (NtSOC1). The yeast-one hybrid assay showed that PmSBP1 was bonded to the promoters of PmSOC1s. In conclusion, a miR156-PmSBP1-PmSOC1s pathway was formed to participate in the regulation of flowering time in P. mume, which provided references for the molecular mechanism of flowering time regulation and molecular breeding of P. mume.

Phytoplankton of the middle Caspian Sea: analysis of changes in the structure of the community over the past decades

Aim. Analysis of changes in quantitative and structural indicators of phytoplankton in the western and central part of the middle Caspian Sea over the past decades, including according to remote sensing data.Material and Methods. The data was obtained in 2004–2008 and 2019–2022 at different seasons of the year at 40 stations in the central and western part of the middle Caspian Sea. Phytoplankton samples were taken from 4–6 layers. A total of 300 samples of phytoplankton were analyzed. Determination of species and counting of the number of cells was carried out under the “Ergaval” light microscope. WoRMS guided matters of nomenclature.Results. The spring phytoplankton is dominated by the species traditional for the Caspian Sea – Cyclotella caspia diatoms and Prorocetrum micans dinoflagellates. The maximum abundance of C. caspia (5.0 x 104 cell/l) was recorded at depths of 35–40 m. In summer, the maximum phytoplankton biomass (2.2 g/m3) was noted in the seasonal thermocline and was formed due to small flagellates and dinoflagellates. Phytoplankton biomass during winter blooms reached 4.5–5.0 g/m3 and was determined by the development of diatoms (up to 96–99%). Winter blooms were formed by the diatom species traditional for the sea, as well as by the Pseudo‐nitschia seriata and Cerataulina pelagica species.Conclusion. It is shown that in the middle Caspian Sea, the winter and autumn seasons are characterized by a highly productive status. In January–February, periodic blooms of diatoms are observed, as confirmed by satellite data and in situ observations. In summer, phytoplankton biomass is determined by the mass development of dinoflagellates in the seasonal thermocline layer, which has not been recorded by remote methods. In the autumn phytoplankton the main role is played by the diatom component, represented mainly by alien species.

Role of ocean circulation and settling of particulate organic matter in the decoupling between the oxygen minimum zone and the phytoplankton productive zone in the Arabian Sea: A modeling study

The oxygen minimum zone has a significant effect on primary production, marine biodiversity, food web structure, and marine biogeochemical cycle. The Arabian Sea oxygen minimum zone (ASOMZ) is one of the largest and most extreme oxygen minimum zones in the world, with a positional decoupling from the region of phytoplankton blooms. The core of the ASOMZ is located to the east of the high primary production region in the western Arabian Sea. In this study, a coupled physical–biogeochemical numerical model was used to quantify the impact of ocean circulation and settling of particulate organic matters (POMs) on the decoupling of the ASOMZ. Model results demonstrate that the increased (decreased) dissolved oxygen replenishment in the western (central) Arabian Sea is responsible for decoupling. The oxygen-rich intermediate water (200–1,000 m) from the southern Arabian Sea enters the Arabian Sea along the west coast and hardly reaches the central Arabian Sea, resulting in a significant oxygen replenishment in the western Arabian Sea high-productivity region (Gulf of Aden) but only a minor contribution in the central Arabian Sea. Besides that, the POMs that are remineralized to consume central Arabian Sea dissolved oxygen comprises not only local productivity in winter bloom but also the transport from the western Arabian Sea high-productivity region (Oman coast) in summer bloom. More dissolved oxygen replenishment in the western Arabian Sea, and higher dissolved oxygen consumption and fewer dissolved oxygen replenishment in the central Arabian Sea could contribute to the decoupling of the ASOMZ and phytoplankton productive zone.

Unveiling the Ability of Witch Hazel (Hamamelis virginiana L.) Bark Extract to Impair Keratinocyte Inflammatory Cascade Typical of Atopic Eczema.

Hamamelis virginiana L. bark extract is a traditional remedy for skin affections, including atopic dermatitis/eczema (AD). Hamamelis preparations contain tannins, including hamamelitannin (HT), although their pharmacological role in AD is still unknown. This study aimed to study the rational for its topical use by considering the impact of crucial biomarkers on AD pathogenesis. A standardized extract (HVE) (0.5–125 μg/mL) was compared to hamamelitannin (HT), its main compound (0.5–5 μg/mL), in a model of human keratinocytes (HaCaTs), challenged with an AD-like cytokine milieu (TNF-α, IFN-γ, and IL-4). HVE inhibited the release of mediators involved in skin autoimmunity (IL-6 and IL-17C) and allergy (TSLP, IL-6, CCL26, and MMP-9) with a concentration-dependent fashion (IC50s < 25 μg/mL). The biological mechanism was ascribed, at least in part, to the impairment of the NF-κB-driven transcription. Moreover, HVE counteracted the proliferative effects of IL-4 and recovered K10, a marker of skin differentiation. Notably, HT showed activity on well-known targets of IL-4 pathway (CCL26, K10, cell proliferation). To the best of our knowledge, this work represents the first demonstration of the potential role of Hamamelis virginiana in the control of AD symptoms, such as itch and skin barrier impairment, supporting the relevance of the whole phytocomplex.

Framework to Extract Extreme Phytoplankton Bloom Events with Remote Sensing Datasets: A Case Study

The chlorophyll-a concentration (CHL) is an essential climate variable. Extremes of CHL events directly reflect the condition of marine ecosystems. Here, we applied the statistical framework for defining marine heatwaves to study the extremes of winter CHL blooms off the Luzon Strait (termed as LZB), northeastern South China Sea (SCS), from a set of remote sensing data. The application was enabled by a recent gap-free CHL dataset, the SCSDCT data. We present the basic properties and the long-term trends of these LZB events, which had become fewer but stronger in recent years. We further statistically analyze the LZB events’ controlling factors, including the submesoscale activity quantified by a heterogeneous index or surface temperature gradients. It was revealed that the submesoscale activity was also a vital modulating factor of the bloom events in addition to the well-understood wind and upwelling controls. This modulation can be explained by the stratification introduced by submesoscale mixed-layer instabilities. In the winter, the intensified winter monsoon provides a background front and well-mixed upper layer with replenished nutrients. During the wind relaxation, submesoscale baroclinic instabilities developed, leading to rapid stratification and scattered submesoscale fronts. Such a scenario is favorable for the winter blooms. For the first time, this study identifies the bloom events in a typical marginal sea and highlights the linkage between these events and submesoscale activity. Furthermore, the method used to identify extreme blooms opens up the possibility for understanding trends of multiple marine extreme events under climate change.

Noctiluca blooms intensify when northwesterly winds complement northeasterlies in the northern Arabian Sea: Possible implications

Wind systems are known as nutrient sources playing significant roles in the oceanic realm and global climate oscillations. This study explores, for the first time, the effect of winds on the winter blooms of the mixotrophic dinoflagellate, the green variant of Noctiluca scintillans (NSG) in the northern Arabian Sea. When the NSG abundance was lower (i.e., <∼10000 cells l−1), it was coupled to silicic acid (H4SiO4), on which diatoms (phytoplankton) in turn depended. At higher abundance (i.e., NSG>∼10000 cells l−1), H4SiO4 and H4SiO4:DIN (dissolved inorganic nitrogen) ratio fell. The NSG was then intensely green and chlorophyll-a richer, attributed to a change in the mode of NSG's nutrition from heterotrophy to autotrophy-dominance. The back-trajectory model revealed that the winds were mostly northeasterly (NE) initially (during February) and were north-westerly (NW) towards the end of winter (March). Separately for the NE and NW winds, the NSG abundance was 10655±18628 and 28896±46225 cells l−1, respectively. The H4SiO4:DIN ratio correspondingly reached <0.2 and ≥0.4. The NSG was modelled with high significance (p<0.001, N=33) versus the NE and NW wind speeds. Thus, while the NE winds deepened the mixed layer and caused nutrient enrichment and phytoplankton production, the NW winds facilitated the recovery of the H4SiO4:DIN ratio and economical use of H4SiO4 for phytoplankton production. It is hypothesized that this process is helped by iron input from NW desert winds during the latter part of winter when the NSG blooms intensify.