Cyst Concentrations Research Articles

The number of artemia bottom cysts (Artemia Leach, 1819) in different hyperhaline lakes of the Altai territory

Artemia cysts are economically significant. One of the components of the reserve is the biomass of artemia cysts submerged to the bottom. 22 hyperhaline lakes of the Altai Territory were studied in 2018–2021. It was found that artemia lived in all the studied lakes, including bisexual populations in 4 lakes, and parthenogenetic populations in 18. The lakes were conditionally divided into 5 groups. 1192 soil samples were selected and processed. The types of sediments were conditionally divided into 6 groups depending on the dominant particles. The dependence of the concentration of bottom artemia cysts on the type of sediments was revealed (r = 0.289, p = 0.001, n = 732). It is determined that the concentration of cysts does not depend on the salinity of the water in the lake, with the same salinity, the density of cysts varies from 0 to several million depending on the type of sediments. The dependence of the concentration of bottom cysts in the summer period on the selected group of lakes was established (r = 0.817, p = 0.1, n = 5). In brine lakes the minimum concentration was observed in spring, in Deep-water and Medium-deep lakes the maximum was observed in summer, in Shallow brine lakes — in autumn. In group of lakes “Shallow, salt precipitates“ and “Drying up in summer” lakes a decrease in the concentration of cysts at the bottom was noted from spring to autumn. The influence of the depth of occurrence on the density of artemia cysts in silt sediments has been studied: in Maloe Yarovoye Lake 63% is in the upper layer, in Kulundinskoye Lake the highest density is in a layer of 5–10 cm, in Bolshoe Yarovoye Lake cysts are evenly distributed in viscous silt at a depth of 5 to 20 cm. The change in the concentration of bottom cysts in autumn and subsequent spring was analyzed to identify the proportion of cysts that have risen from the bottom. Up to 98% of cysts float in Shallow lakes, 4–62% in Deep and Medium-deep lakes.

Geographic distribution of modern dinoflagellate cysts in surface sediments of the Arabian Sea: significance of taxa and morphometry as potential ecological indicators.

Studies on dinoflagellate cysts in the Arabian Sea (AS) are limited to the coastal waters, but no information from the deeper depths. The dinoflagellate cyst assemblages in surface sediment samples (0-2cm) from the deeper depths (up to ~ 4500m) of central (oxygen minimum zone (OMZ)) and southeastern (oligotrophic) AS revealed that the relatively good numbers of cyst concentrations reach deeper depths of OMZ (3505m) and oligotrophic (4368m) regions, but the former harbored more cyst concentrations than the latter. The cyst concentration and species count (including HAB species) recorded here are lower compared to the eastern (EAS) and western (WAS) AS, but the autotrophic cyst dominance (74-83%) at deeper depths is in contrast with the heterotrophic dominance in coastal AS. Of the recorded 41 cyst species (belonging to 18 genera), four species (cyst of Cladopyxis sp., Operculodinium janduchenei, Stelladinium bifurcatum, and Protoperidinium monospinum) from the deepest part of oligotrophic AS form the first report. In contrast, Spiniferites and Lingulodinium cysts were common occurrences. Taxonomic comparison with literature revealed (i) the prevalence of more cosmopolitan species (32 species) which could be due to the prevalence of large and small-scale lateral transport of cysts in oligotrophic regions followed by OMZ and coastal regions, respectively, and (ii) very few region-specific species, i.e., cyst of Protoperidinium latissimum, Lejeunecysta sabrina, cyst of Protoperidinium denticulatum in EAS and Impagidinium patulum, and I. strialatum, in WAS. Interestingly, variability in the morphometry was evident between the coastal and open oceans in some cosmopolitan cysts, e.g., Operculodinium centrocarpum and Lingulodinium machaerophorum. These findings from the less studied pelagic regions will contribute to the growing knowledge of dinoflagellate cyst distribution patterns and highlight the significance of cyst taxa and morphology as potential ecological indicators for AS.

Use of an acrylamide-based anionic polymer for the concentration and removal of Giardia duodenalis cysts from high-turbidity water samples

The increasing investigation into environmental contamination by Giardia spp. cysts and its impact on public health has spurred interest in developing more sensitive methods for detecting these protozoa, particularly in water. However, these methods remain complex and costly. This study evaluated the concentration and removal efficiency of Giardia duodenalis cysts using an acrylamide-based anionic flocculant polymer (AFP) in filter backwash water samples from a water treatment plant (WTP) located in Blumenau City, southern Brazil, and compared them with the calcium carbonate flocculation technique (CCF), which is routinely used for water matrices with high turbidity. The average recovery rates of G. duodenalis cysts using CCF and AFP were 33.33% and 43.33%, respectively, with an average turbidity reduction of 98.39% and 98.78%. The use of an anionic flocculant polymer proved to be an efficient alternative for the concentration and removal of protozoan cysts in water samples with high turbidity. It is important to highlight that the development and application of new studies and strategies aimed at increasing the efficiency of the removal of these organisms from complex environmental matrices would bring benefits to public health and promote a One Health perspective. Keywords: cyst recovery, high turbidity, water.

Year-round monitoring of three water sources in Québec, Canada, reveals site-specific differences in conditions for Cryptosporidium and Giardia contamination.

Cryptosporidium and Giardia are protozoan parasites responsible for gastrointestinal illnesses in humans and in animal species. The main way these parasites are transmitted is by ingestion of their (oo)cysts in drinking water. Monitoring (oo)cysts in water sources is beneficial to evaluate the quality of raw water supplying treatment plants. Currently, the only standardized protocol to enumerate these parasites from water samples is United States Environmental Protection Agency (USEPA) Method 1623.1. With this method, we monitored three major water sources in Quebec over a year to assess temporal and geographical variations of these parasite (oo)cysts. These three water sources have independent watersheds despite being in the same region. We found a general pattern for Giardia, with high concentrations of cysts during cold and transition periods, and significantly lower concentrations during the warm period. Cryptosporidium's concentration was more variable throughout the year. Statistical correlations (Pearson's correlation coefficients) were established between the concentration of each parasite and various environmental parameters. The three study sites each showed unique factors correlating with the presence of both protozoa, supporting the idea that each water source must be seen as a unique entity with its own particular characteristics and therefore, must be monitored independently. Although some environmental parameters could be interesting proxies to the parasitic load, no parameter was strongly correlated throughout the whole sampling year and none of the parameters could be used as a single proxy for all three studies sources.

Estimation and evaluation of the risks of protozoa infections associated to the water from a treatment plant in southern Brazil using the Quantitative Microbiological Risk Assessment Methodology (QMRA).

In this study, the Quantitative Microbial Risk Assessment (QMRA) methodology was applied to estimate the annual risk of Giardia and Cryptosporidium infection associated with a water treatment plant in southern Brazil. The efficiency of the treatment plant in removing protozoa and the effectiveness of the Brazilian legislation on microbiological protection were evaluated, emphasizing the relevance of implementing the QMRA in this context. Two distinct approaches were employed to estimate the mechanical removal of protozoa:The definitions provided by the United States Environmental Protection Agency (USEPA), and the model proposed by Neminski and Ongerth.Although the raw water collected had a higher concentration of Giardia cysts than Cryptosporidium oocysts, the estimated values for the annual risk of infection were significantly higher for Cryptosporidium than for Giardia. From a general perspective, the risk values of protozoa infection were either below or very near the limit set by the World Health Organization (WHO). In contrast, all the risk values of Cryptosporidium infection exceeded the threshold established by theUSEPA. Ultimately, it was concluded that the implementation of the QMRA methodology should be considered by the Brazilian authorities, as the requirements and guidelines provided by the Brazilian legislation proved to be insufficient to guarantee the microbiological safety of drinking water. In this context, the QMRA application can effectively contribute to the prevention and investigation of outbreaks of waterborne disease.

Reducing costs of Giardia spp. cyst enumeration using machine learning-based systems

Abstract Giardia spp. cyst enumeration is a laboratory procedure that is frequently required in water treatment-related research. Currently, detection conducted by experts using fluorescence microscopy on samples stained with specific markers for Giardia spp. cysts is still the standard method, despite its high costs limiting its usage worldwide and, ultimately, hindering waterborne analyses in low-income countries. We present an approach based on darkfield imaging and machine learning to reduce costs associated with Giardia spp. cyst enumeration and the lack of experts. Automated counts were compared to manual counts, achieving an average sensitivity (SE) rate of 88%, specificity (SP) of 100% and accuracy of 88% across a wide range of cyst concentrations. By using machine learning in conjunction with darkfield microscopy, a low-cost illumination technique that can be easily integrated into standard laboratory microscopes, we have significantly reduced the costs associated with Giardia spp. cyst detection, all while still maintaining the SE and SP of fluorescence microscopy. Based on the findings, the proposed system has the potential to be a useful tool to enumerate Giardia spp. cyst suspensions. It can be accessed by virtually any microbiology laboratory as it is consumable-free and expert-independent.

A two-year monitoring of Cryptosporidium spp. oocysts and Giardia spp. cysts in freshwater and seawater: A complementary strategy for measuring sanitary patterns of recreational tropical coastal areas from Brazil

Primary contact recreation is an important transmission route of gastroenteric protozoa such as Cryptosporidium and Giardia. However, data on the environmental epidemiology of both protozoa in Brazilian coastal areas still need to be available. The main goal of this study was to perform environmental monitoring and quantify the concentration of Cryptosporidium oocysts and Giardia cysts on the main beaches of the state of Paraná, Brazil, as a complementary tool for measuring the sanitary quality of bathing waters for two years. A total of 144 water samples were harvested monthly for two years from Guaratuba, Caiobá and Matinhos beaches (72 samples of seawater and 72 of freshwater) to search for pathogenic protozoa. Protozoa were concentrated by the membrane filtration technique and visualized by direct immunofluorescence assay (IFA). All positive samples by IFA were submitted for DNA extraction for PCR analysis. Fecal indicator bacteria (FIB) were enumerated by conventional microbiological techniques. Both protozoa were detected on all beaches during the two-year monitoring period. At least one protozoa were detected in 58.3% (n = 14) months of sampling, totaling 24 positive samples. Guaratuba was the most contaminated beach followed by Caiobá and Matinhos. Giardia spp. was detected in 15, Cryptosporidium spp. in seven and both parasites in two samples. Giardia DNA was confirmed on two beaches, and Cryptosporidium was detected for the first time through molecular assays in a coastal area of Brazil. An essential impact of FIB was observed in the first year and a reduction in contamination rates in the second year of monitoring. This is the first study conducted in the country in different environments that composes coastal areas to monitor together parasitological and microbiological quality for extended periods. The monitoring of coastal waters can guide environmental agencies aiming to improve the sanitary quality of beaches and safeguard public health.

Diatom Assemblages in the Sediment Traps in Lake Onega

The paper presents the first study of the composition and structure of the diatom assemblages from sediment traps installed in different parts of Lake Onega. 171 species and intraspecific diatom taxa were observed belonging to 59 genera. The predominance of planktonic diatoms is favored by large depths of the lake and a small area of the littoral zone. Aulacoseira islandica and A. subarctica, the most abundant species in spring phytoplankton in Lake Onega dominate in the sediment-traps diatom assemblages. In the sites subject to anthropogenic eutrophication, Aulacoseira ambigua is numerous as well. In a number of sites Lindavia radiosa and Pantocsekiella tripartita are among the subdominating species, while P. schumannii, Stephanodiscus neoastraea and Stephanodiscus sp. are less common. Higher proportions of periphytic Tabellaria fenestrata were recorded in the sites with the largest areas colonized by macrophytes. In all sampling sites, neutrophilous oligo-mesotrophic and oligo-hypereutrophic taxa prevail in the diatom assemblages. The predominance of two or three species in the diatom assemblage results in low values of the floristic diversity index. More diverse diatom assemblages were found in rathers isolated bays. Concentrations of diatom valves and chrysophyte cysts in sediment traps material were also calculated.

Evaluation of organic-walled dinoflagellate cyst distributions in coastal surface sediments of the China Seas in relation with hydrographic conditions for paleoceanographic reconstruction

Dinoflagellate cysts are commonly used to reconstruct past climatic, oceanographic and environmental conditions. Such applications are based on the relationship between modern dinoflagellate cysts and environmental parameters. To evaluate cyst diversity and driving factors of their distributions in sediments of the China Seas for paleoenvironmental reconstruction, dinoflagellate cysts were analyzed in 18 surface sediment samples from the Bohai Sea, the Yellow Sea (YS), the East China Sea and the South China Sea (SCS). A total of 59 dinoflagellate cyst taxa were identified with the greatest diversity reported in the SCS. The highest cyst concentrations were found in the YS, where Spiniferites ramosus, Spiniferites spp., and cysts of Pentapharsodinium spp. were predominant in the assemblages. The Yellow Sea Warm Current is likely creating the environment favoring the high numbers of Spiniferites ramosus in the YS. The highest Brigantedinium spp. abundances were observed near the Pearl River mouth and are positively correlated with sea-surface temperature (SST) in August. Spiniferites hyperacanthus, S. mirabilis, S. pacificus, and Lingulodinium spp. were most abundant in the SCS. In contrast, cysts of Protoperidinium spp. and Selenopemphix quanta were more common at the sites directly influenced by coastal upwelling rather than by river discharges. Redundancy Analysis results show that SST, sea-surface salinity (SSS) and nitrate concentration in water are statistically significant parameters influencing the cyst assemblages. We also examined the morphological characteristics of Spiniferites ramosus and recommend grouping S. bulloideus with S. ramosus in the northwest Pacific dataset for quantitatively reconstructing paleoceanographic conditions.

An unprecedented bloom of Lingulodinium polyedra on the French Atlantic coast during summer 2021

At the end of July 2021, a bloom of Lingulodinium polyedra developed along the French Atlantic coast and lasted six weeks. The REPHY monitoring network and the citizen participation project PHENOMER contributed to its observation. A maximum concentration of 3,600,000 cells/L was reached on the 6th of September, a level never recorded on French coastlines. Satellite observation confirmed that the bloom reached its highest abundance and spatial extension early September, covering about 3200 km2 on the 4th of September. Cultures were established, and morphology and ITS-LSU sequencing identified the species as L. polyedra. The thecae displayed the characteristic tabulation and sometimes a ventral pore. The pigment composition of the bloom was similar to that of cultured L. polyedra, confirming that phytoplankton biomass was dominated by this species. The bloom was preceded by Leptocylindrus sp., developed over Lepidodinium chlorophorum, and was succeeded by elevated Noctiluca scintillans concentrations. Afterwards, relatively high abundance of Alexandrium tamarense were observed in the embayment where the bloom started. Unusually high precipitation during mid-July increased river discharges from the Loire and Vilaine rivers, which likely fueled phytoplankton growth by providing nutrients. Water masses with high numbers of dinoflagellates were characterized by high sea surface temperature and thermohaline stratification. The wind was low during the bloom development, before drifting it offshore. Cysts were observed in the plankton towards the end of the bloom, with concentrations up to 30,000 cysts/L and relative abundances up to 99%. The bloom deposited a seed bank, with cyst concentrations up to 100,000 cysts/g dried sediment, particularly in fine-grained sediments. The bloom caused hypoxia events, and concentrations of yessotoxins up to 747 μg/kg were recorded in mussels, below the safety threshold of 3,750 μg/kg. Oysters, clams and cockles also were contaminated with yessotoxins, but at lower concentrations. The established cultures did not produce yessotoxins at detectable levels, although yessotoxins were detected in the sediment. The unusual environmental summertime conditions that triggered the bloom, as well as the establishment of considerable seed banks, provide important findings to understand future harmful algal blooms along the French coastline.

Environmental Factors Associated with Cryptosporidium and Giardia.

Environmental factors significantly influence the transmission of intestinal protozoan diseases. Cryptosporidiosis and giardiasis are important zoonotic diseases characterized by diarrhea, and are mainly water or foodborne diseases caused by fecal-borne oocysts. The One Health approach effectively addresses environmentally influenced zoonotic diseases. However, the impact of environmental factors on the survival of Cryptosporidium/Giardia (oo)cysts or disease transmission is mostly uncharacterized. Associations between cryptosporidiosis and giardiasis incidence and environmental variables (e.g., climatic conditions, soil characteristics, and water characteristics) have been reported; however, the identified relationships are not consistently reported. Whether these are country-specific or global observations is unclear. Herein, we review the evidence for the influence of environmental factors on Cryptosporidium/Giardia and corresponding diseases from three perspectives: climatic, soil, and water characteristics. The (oo)cyst concentration or survival of Cryptosporidium/Giardia and the incidence of corresponding diseases are related to environmental variables. The associations identified varied among studies and have different levels of importance and lag times in different locations. This review summarizes the influence of relevant environmental factors on Cryptosporidium/Giardia from the One Health perspective and provides recommendations for future research, monitoring, and response.

Distribution of dinoflagellate cyst assemblages in surface sediments of Magellan fjords and channels (Patagonia, Chile) with a focus on harmful species: An overview on environmental scenario

Several dinoflagellate species form benthic resting cysts in their life cycle. In order to study the composition, abundance and distribution of cyst assemblages, with a focus on harmful species, thirty-one surface sediment samples from the Magellan fjords and channels system were analysed. In situ (temperature, salinity, inorganic nutrients, dissolved oxygen, organic matter, and chlorophyll-a) and five-year (salinity, temperature, dissolved oxygen, and chlorophyll-a) measurement data were analysed to obtain an overview on environmental scenario. A total of 56 cyst morphotypes were recorded, some of which were identified for the first time for the Chilean coast (Dactylodinium cf. arachnoides, Impagidinium cf. velorum, Archaeperidinium sp., Protoperidinium haizhouense, Protoperidinium sinuosum, Protoperidinium tricingulatum, and Dubridinium cf. ulsterum). In vitro germination of cysts allowed the vegetative form of the species of the order Suessiales to be determined. Total cyst concentrations were highly variable, ranging from 145 to 5453 cysts mL−1 of wet sediment (mean 1246 ± 1061 cysts mL−1), with the lowest cyst values in the area adjacent to the Southern Patagonian Ice Field. Pentapharsodinium dalei and Protoperidinium conicoides generally dominated (%) the cyst assemblages. The harmful species Alexandrium catenella and Alexandrium ostenfeldii were not abundant and sparsely distributed, while Protoceratium reticulatum was widespread and highly abundant with Gonyaulax spinifera in Inutil Bay (Magellan Strait). Cluster and nMDS analyses performed with cyst concentrations of the 56 taxa in the 31 stations formed seven cyst assemblage clusters, reflecting high environmental variability. Canonical correspondence analyses performed with cyst concentrations and in situ and long-term environmental data showed different ecological signals, demonstrating that in situ parameters must be used carefully when studying cysts in surface sediments.

Inactivation of Giardia intestinalis cysts in water using a sonochemical method based on mid-high-frequency waves

Giardia intestinalis is a pollutant of food and water, resistant to conventional disinfection treatments and its elimination requires effective methods action. Herein, mid-high-frequency ultrasound (375 kHz), which produces HO• and H2O2, was used as an alternative method of treatment to inactivate Giardia intestinalis cysts in water. The effect of ultrasound power (4.0, 11.2, 24.4 W) on the sonogeneration of radicals was tested, showing that 24.4 W was the condition most favorable to treat the parasite. The viability of the protozoan cysts was evaluated using the immunofluorescence technique and vital stains, showing this protocol was useful to quantify the parasite. The sonochemical method (at 375 kHz and 24.4 W) was applied at different treatment times (10, 20, and 40 min). A significant decrease in the protozoan concentration (reduction of 52.4% of viable cysts) was observed after 20 min of treatment. However, the extension of treatment time up to 40 min did not increase the inactivation. Disinfecting action was associated with attacks on the Giardia intestinalis cyst by sonogenerated HO• and H2O2 (which may induce structural damage, even the cell lysis). For future work is recommended to test combinations with UVC or Fenton process to enhance the inactivating action of this method.•Mid-high-frequency ultrasound produces HO• and H2O2 profitable to inactivate Giardia intestinalis.•Immunofluorescence technique and vital stains allowed us to quantify the parasite viability.•Giardia intestinalis cysts concentration decreased by 52.4% after only 20 min of sonication.

Spatially explicit model of the Cryptosporidium and Giardia disease burden from surface and ground waters in urban and rural areas of the Three Gorges Reservoir watershed in Chongqing, China

Cryptosporidium and Giardia (major causes of diarrhea) are widely distributed in Chinese source waters and threaten human health. A new spatially explicit GloWPa-TGR-Crypt-Giar C1 model is presented to simultaneously estimate mean monthly (oo)cyst concentrations in surface and ground waters in the Three Gorges Reservoir (TGR) watershed. A quantitative risk assessment of protozoal infections considered different source waters, transmission pathways, regions, susceptible subpopulations, and drinking water treatments. Monthly mean Cryptosporidium oocyst and Giardia cyst concentrations ranged between 0.5–19.3 oocysts/10 L and 0.2–5.0 cysts/10 L in surface water, respectively, and 0.007–0.3 oocysts/10 L and 0.002–0. 2 cysts/10 L in groundwater. The cumulative disease burdens attributable to cryptosporidiosis and giardiasis were, respectively, 5.77×10−5 DALYs (disability-adjusted life years/person/year) and 4.63×10−6 DALYs in urban areas, and 6.35×10−4 DALYs and 8.84×10−5 DALYs in rural areas, which were much higher than the reference risk level recommended by the World Health Organization ({10}^{-6} DALYs). The annual burden associated with consuming surface water was calculated to be 3.84×10−4 DALYs for Cryptosporidium and 5.10times {10}^{-5} DALYs for Giardia, whereas consuming groundwater entailed the lower burdens (1.26×10−5 and 3.50×10−6 DALYs, respectively). Most DALYs were a consequence of consumption of directly supplied surface water. Fifty percent of the health burden was carried by immunodeficiency with HIV. Children (0–4 years) were more likely to have an individual disease burden than adults (15–64 years). Males were more susceptible than females. Improving sanitation through adequate ozone and microfiltration treatment should be considered when attempting to reduce disease burden. Sensitivity analysis highlighted the importance of reducing (oo)cyst loads to protect the watershed. The methodology and results described will help in evaluating and reducing the burden of protozoal infection associated with surface and ground waters in the TGR and similar watersheds.Graphical

Salinity indicators in sediment through the fluvial-to-marine transition (Fraser River, Canada)

Many sediment attributes have been proposed as proxies for determining salinity conditions under which sediment is deposited, and six attributes (Sr/Ba-HAc, Sr/Ba-NH4Ac, δ13Corg, C/N, and the relative abundances and concentrations of dinoflagellate cysts) are compared here. In this paper, sediment attributes from the Fraser River Delta, Canada and surrounding coastal areas are compared by depositional position along the fluvial-to-marine transition, by salinity, and by sedimentological characteristics. Along the fluvial-to-marine transition, most attributes exhibit distinct trends between parts of the river that experience sustained marine water (saltwater) influence over seasonal and tidal timeframes, and parts that experience only freshwater or periodic saltwater influence. No attributes are reliable indicators of depositional position where saltwater incursion is short lived or where water is fresh. Where marine influence is sustained, Sr/Ba-HAc and Sr/Ba-NH4Ac are the most reliable positional indicators along the fluvial-to-marine transition. When compared strictly to salinity, Sr/Ba-HAc, Sr/Ba-NH4Ac, and δ13Corg all correlate predictably except in delta front and prodelta settings. Our data show that all six sediment attributes are heavily impacted by river-derived sedimentation, and it is not appropriate to compare values from strongly river-influenced settings (e.g., deltas) with those from weakly river-influenced settings (e.g., bays and estuaries).

Dinoflagellate cysts production, excystment and transport in the upwelling off Cape Blanc (NW Africa)

To extend the understanding of dinoflagellate cysts production, excystment and vertical/lateral transport in the water column, we compared upper water cyst export production with cysts associations and concentrations in the subsurface nepheloid layer, bottom nepheloid layer and deeper water column during active upwelling off Cape Blanc (NW Africa) in August 2020. Export production was collected by two drifting trap surveys; DTS1 in an active upwelling cell for 4 days and DTS2 in an offshore drifting upwelling filament for 2 days. Subsurface, bottom nepheloid layers and deeper waters were sampled by in-situ pumps along two transects perpendicular to the shelf break. During DTS1, light limitation hampered phytoplankton production which might have influenced cyst production negatively due to up- and downward movement of water masses. Cyst export production increased at the rim of the upwelling cell. For DTS2, upwelling filament cyst export production was up to 3 times lower than that of DTS1. Echinidinium delicatum had highest relative and absolute abundances in the active upwelling, Echinidinium zonneveldiae and Bitectatodinium spongium in the upwelling filament, and Impagidinium spp. and cysts of Gymnodinium microreticulatum/nolleri at the most distal stations. Comparison of concentrations of cysts with and without cell contents showed that the majority of cysts hatched before reaching deeper waters and displayed a dormancy period of less than 6 days. About 5% of the living cysts reached deeper waters and/or the ocean floor. Living cysts were transported offshore in the upwelling filament. In case ships exchange ballast waters in the studied region, they will take up laterally transported living cysts. Upon release of the ballast waters in the port of arrival, these cysts have the potential to become “invader species” that can threaten economy and/or health. Lateral transport of cysts was observed in the bottom nepheloid layer and in deeper waters (800 - 1200m depth) with a maximal extension of about 130km off the shelf break. Therefore, sediments in the region will contain a mixture of regionally and locally produced dinoflagellate cysts. This insight contributes to the improvement of environmental reconstructions of the Cape blanc upwelling system based on downcore cyst associations.

Distribution of Dinoflagellate Cysts in Surface Sediments From the Qingdao Coast, the Yellow Sea, China: The Potential Risk of Harmful Algal Blooms

Surface sediments were collected from three sea areas of the Qingdao coast, the Yellow Sea, China, namely, the inner Jiaozhou Bay, the Laoshan coast, and the Amphioxus Reserve area in November to December 2017. Dinoflagellate cysts were observed in the sediments, focusing on the distribution of toxic and harmful species. Contents of biogenic elements were analyzed to reveal their relationships to cysts. A total of 32 cyst taxa were identified, including 23 autotrophic and 9 heterotrophic taxa. Cyst concentrations ranged from 83.3 to 346.5 cysts/g D Wt with an average of 210.7 cysts/g D Wt. Generally, cysts of autotrophic dinoflagellates dominated in sediments from the Qingdao coast with proportions of 41.05%–90.25%. There were no dominant group in cyst assemblages; cysts of Protoperidiniaceae, Suessiales, and Calciodinelloideae showed similar contributions. Cyst assemblages were quite different in the inner Jiaozhou Bay reflected by the lower species richness, diversity, and cyst concentration. Results from the redundancy analysis (RDA) demonstrated the influence of biogenic elements on cyst assemblages, which explained well why the three sea areas with different degrees of human activities showed different dinocyst storages. Notably, 17 harmful algal bloom (HAB) dinoflagellate cysts were identified in this study, including cysts of those producing toxins that may damage human health and marine animals. Some of these cysts occurred widely and dominantly in this study, such as cysts of Gonyaulax spinifera, Azadinium trinitatum, Scrippsiella acuminata, and Biecheleria halophila, suggesting the potential risk of HABs in the Qingdao coastal area.

Label-free detection and enumeration of Giardia cysts in agitated suspensions using in situ microscopy

Laboratory procedures performed in water treatment studies frequently require the characterization of (oo)cyst suspensions. Standard methods commonly used are laborious, expensive and time-consuming, besides requiring well-trained personnel to prepare samples with fluorescent staining and perform analysis under fluorescence microscopy. In this study, an easy cost-effective in situ microscope was assessed to acquire images of Giardia cysts directly from agitated suspensions without using any chemical labels or sample preparation steps. An image analysis algorithm analyzes the acquired images, and automatically enumerates and provides morphological information of cysts within 10 min. The proposed system was evaluated at different cyst concentrations, achieving a limit of detection of ~30 cysts/mL. The proposed system overcomes cost, time and labor demands by standard methods and has the potential to be an alternative technique for the characterization of Giardia cyst suspensions in resource-limited facilities, since it is independent of experts and free of consumables.

Human health risk assessment for (re)emerging protozoan parasites in surface water used for public supply and recreational activities

Gastrointestinal diseases caused by protozoan parasites remain a major challenge in developing countries and ingestion of contaminated surface water represents one of the main sources by which these diseases are contracted. This study assessed the risk of infection and diseases caused by Cryptosporidium spp. and Giardia sp. due to ingestion of surface water used for public supply and recreational activities, focusing on the southeastern Brazilian Pardo River and applying the USEPA 1623 method to quantify (oo)cyst concentrations. Infection and disease probabilities due to ingestion of drinking water or during recreational activities were estimated using the Quantitative Microbial Risk Assessment (QMRA) approach. Mean concentrations of Cryptosporidium spp. and Giardia sp. in surface water ranged from 0.2 to 0.4 oocysts L-1 and 0.2 to 4.4 cysts L-1, respectively. Considering public water supply, annual infection probabilities were higher for adults than children and exceeded the USEPA limit; also, disease probabilities were higher for adults than children. For recreational activities, annual infection and disease probabilities were higher for children, followed by men and women. The occurrence of both parasites likely reflects raw sewage discharge, effluent from sewage treatment plants, and diffuse sources of pollution, such as runoff from pasture lands and deforested riparian forest corridors. Our results highlight substantial infection risks by both parasite types after conventional treatment of water used for public supply and also call for careful monitoring of water bodies used for recreational purposes.

Last Interglacial (MIS 5e) sea surface hydrographic conditions in coastal southern California based on dinoflagellate cysts

The first high resolution record of dinoflagellate cysts ∼110–155 kyr over Termination II and the Last Interglacial in the Santa Barbara Basin, California from ODP Hole 893A details a complex paleoceanographic history. Variation in cyst relative abundances, concentrations, and diversity reflects climatic and ocean circulation changes, and the assemblages are used to make qualitative reconstructions of sea surface temperature (SST) and annual primary productivity. The dominance of heterotrophic Brigantedinium spp. throughout the section indicates an important influence of coastal upwelling on the basin. Based on the dinoflagellate cyst assemblages, five zones are identified, which approximately correspond to the marine isotope stage boundaries and their associated changes in SST and sea level. Cooler intervals, MIS 6 and MIS 5d, are characterized by cold-water indicator species Selenopemphix undulata whereas thermophilic taxon Spiniferites mirabilis characterizes a warm MIS 5e. In contrast to other studies in the Pacific, the data exhibits a one to two-thousand-year cooling event ∼129 kyr that correlates to the Termination II sea level still-stand of the two-step deglaciation. A significant increase in cyst concentrations in the latest MIS 5e implies enhanced primary production due to increased seasonal upwelling and the warm, nutrient rich waters entering the basin after sea level stabilizes near modern levels. The hydrological evolution and cyst signal of the Last Interglacial is similar to the development of the Holocene in the Santa Barbara Basin, but the sustained presence of Spiniferites mirabilis across MIS 5e indicates SSTs were higher than modern conditions. • First high resolution dinocyst study in temperate northeastern Pacific during MIS5e. • SST, upwelling, and sea-level changes drive dinocyst variation in the SBB. • Spiniferites mirabilis and Selenopemphix undulata are best indicators of SST change. • Dinocyst paleoecology consistent with previous geochemical and palynology signals. • Termination II and MIS5e dinocyst assemblages are comparable to Holocene SBB cysts.