Uncovering the diversity of microalgal harmful species in Chile through multidisciplinary characterization.

Dinophysis spp. synthesize lipophilic toxins and form harmful algal blooms (HABs) across the globe. Zooplankton can play a role in controlling HABs and be a vector for HAB toxins; however, no study has explored the grazing and survival of copepods fed cultured Dinophysis. Here, the copepod Acartia tonsa isolated from New York, USA, was fed 3 strains of D. acuminata from the eastern USA (Massachutsetts, New York, Virginia), as well as 2 non-toxic prey (Rhodomonas salina and Gymnodinium aureolum). Grazing and survival rates of A. tonsa were quantified along with toxins. A. tonsa fed on D. acuminata at rates similar to R. salina and G. aureolum. Mixed-prey experiments suggested that D. acuminata was not acutely toxic to A. tonsa. Extracellular levels of okadaic acid (OA) significantly increased (p ≤ 0.05) and extracellular pectenotoxin (PTX2) increased by 50% upon exposure to copepods, suggesting that grazers stimulated extracellular toxin release. During 3 wk survival experiments, copepods consuming D. acuminata as a sole food source displayed significantly lower survival rates compared to those fed a control diet of R. salina (p < 0.05). This depressed survivorship was ameliorated by feeding the copepods a diet of D. acuminata mixed with G. aureolum, suggesting that nutritional deficiencies drove mortality. Since grazing on Dinophysis may be low when prey abundance is low, reduced grazing may contribute to bloom development; however, as blooms intensify, grazing may increase, potentially causing a reduction in copepod survival and continued bloom progression. Finally, grazing-induced increases in OA and PTX2 could enhance the introduction of Dinophysis-derived toxins into food webs.

Harmful algal blooms (HABs) such as those formed by the ichthyotoxic dinoflagellate, Margalefidinium (aka Cochlodinium) polykrikoides can have adverse effects on bivalves. While M. polykrikoides has caused significant die offs of bivalves and other marine organisms, the Northern quahog or hard clam, Mercenaria mercenaria, is comparatively more resistant to this HAB. This study quantified clearance rates of juvenile hard clams (10-20 mm) exposed to three different North American populations of M. polykrikoides (bloom, strain CP1, strain CPSB-1G) as well as the nonharmful cryptophyte, Rhodomonas salina and the nonharmful dinoflagellate, Gymnodinium aureolum, in single and mixed algal exposures. Multiple biovolume exposures with M. polykrikoides bloom water and R. salina (1,000, 1,500, 3,000 cells mL-1M. polykrikoides biovolume equivalent) were completed to assess the effects of increasing biomass on hard clam clearance rates and selection. Hard clams opened and actively cleared algal mixtures at and below 1,000 M. polykrikoides cells mL-1. During single species exposures, strain CPSB-1G and R. salina were cleared significantly faster than wild M. polykrikoides populations and strain CP1. During mixed exposures, R. salina was cleared significantly faster than CPSB-1G but not other M. polykrikoides populations and there was no difference between hard clam clearance rates of G. aureolum and R. salina. Clearance rates of M. polykrikoides at ≥1,500 cells mL-1M. polykrikoides/R. salina mixtures were not significantly different than zero unlike clearance of those at <1,000 cells mL-1 indicating a density dependent effect of blooms. Collectively, the results demonstrate that hard clams can actively clear M. polykrikoides cells at moderate (≤1,000 cells mL-1) but not elevated (> 1,000 cells mL-1) bloom densities. Given this, and the documented survival of hard clams during blooms, M. mercenaria may be candidate for aquaculture and restoration in regions prone to HABs caused by M. polykrikoides.

Wolny, J.L.; McCollough, C.B.; Rosales, D.S., and Pitula, J.S., 2022. Harmful algal bloom species in the St. Martin River: Surveying the headwaters of northern Maryland's coastal bays. Journal of Coastal Research, 38(1), 86–98. Coconut Creek (Florida), ISSN 0749-0208. In the spring seasons of 2015 through 2017, the Maryland Department of Natural Resources and the University of Maryland Eastern Shore monitored the phytoplankton community of the headwaters of the St. Martin River, a tributary at the northern end of Maryland's coastal bays, to determine the presence and extent of harmful algal bloom (HAB) species. The phytoplankton community composition, including HAB species, was examined via weekly sampling from March through June. In 2015, HAB events began in late March with a bloom of Gymnodinium aureolum, representing the first report of this species in Maryland waters. Following the G. aureolum bloom, blooms of other HAB species occurred, including Dinophysis acuminata, Karlodinium veneficum, Prorocentrum minimum, and a species in the Alexandrium minutum complex. Initiating at the NW extent of the St. Martin River, these blooms became distributed both temporally and spatially throughout the study area. These same species were detected in 2016 and 2017 but at lower concentrations than those seen in 2015. High concentrations and diverse blooms of HAB species in 2015 may have been due to significant rain events and/or an increase in ammonium levels from a legacy nutrient pool following the removal of the Bishopville Dam, located upstream of the study site in November 2014. This study provides a baseline assessment for future work on harmful algae in the St. Martin River watershed and a look into phytoplankton community dynamics after a dam removal.

Abstract Algal blooms are natural phenomena that may cause human health problems, millions of dollars in losses and ecological disasters worldwide. Anthropogenic pressures like eutrophication may increase the frequency and intensity of these phenomena. The Black Sea is characterized by rapid changes in salinity and temperature in surface waters. In addition, it has suffered increasing environmental pressure from human activities. This work presents the first cultures of Gymnodinium aureolum to be isolated from the Black Sea. Morphological and phylogenetic analyses confirmed our strain as G. aureolum. The effects of temperature and salinity on growth were tested in experiments combining two temperatures and five salinities in 10 experimental treatments. This provides baseline data on the physiological adaption and acclimatization potential of the species to bloom under present and future climatic scenarios in the Black Sea. Gymnodinium aureolum grew exponentially in all experimental treatments, except for cultures at salinity 5. Growth rate increased significantly with increasing temperature reaching the maximum at 20 °C and salinity 15 (0.38 ± 0.02 d−1). This suggests an adaptation to the salinity and temperature of Black Sea waters and, together with previous records of G. aureolum in both water and sediments, supports the idea that this may be a bloom-forming population of G. aureolum.

Molecular phylogeny of the parasitic dinoflagellate Syltodinium listii (Gymnodiniales, Dinophyceae) and generic transfer of Syltodinium undulans comb. nov. (= Gyrodinium undulans)

Feeding by the harmful phototrophic dinoflagellate Takayama tasmanica (Family Kareniaceae)

Abstract To investigate the disparity between plankton and cyst records, sediment slurry cultures were used to isolate the motile stage of dinoflagellates from Caspian Sea sediment. This has resulted in new records for this area ofKryptoperidinium foliaceum,Gymnodinium aureolumandWoloszynskiasp. and for the cyst record,Scrippsiella acuminata. TwoGonyaulaxspecies were isolated, one was identified asGonyaulax balticaand the other an unknown species. Cultures ofLingulodinium polyedrawere also isolated. The approach of using slurries was useful to provide cultures from sediments that were relatively poor in dinoflagellate cysts with contents.

Mixotrophy in the phototrophic dinoflagellate Takayama helix (family Kareniaceae): Predator of diverse toxic and harmful dinoflagellates

Red tides in Shiwha Bay, western Korea: A huge dike and tidal power plant established in a semi-enclosed embayment system

The heterotrophic dinoflagellate Gyrodiniellum shiwhaense n. gen., n. sp. is described from live cells and from cells prepared for light, scanning electron, and transmission electron microscopy. Also, sequences of the small subunit (SSU) and large subunit (LSU) of rDNA have been analyzed. The episome is conical, while the hyposome is ellipsoid. Cells are covered with polygonal amphiesmal vesicles arranged in 16 horizontal rows. Unlike other Gyrodinium-like dinoflagellates, the apical end of the cell shows a loop-shaped row of five elongate amphiesmal vesicles. The cingulum is displaced by 0.3-0.5 × cell length. Cells that were feeding on the dinoflagellate Amphidinium carterae Hulburt were 9.1-21.6 μm long and 6.6-15.7 μm wide. Cells of G. shiwhaense contain nematocysts, trichocysts, a peduncle, and pusule systems, but they lack chloroplasts. The SSU rDNA sequence is >3% different from that of the six most closely related species: Warnowia sp. (FJ947040), Lepidodinium viride Watanabe, Suda, Inouye, Sawaguchi & Chihara, Gymnodinium aureolum (Hulburt) Hansen, Gymnodinium catenatum Graham, Nematodinium sp. (FJ947039), and Gymnodinium sp. MUCC284 (AF022196), while the LSU rDNA is 11-12% different from that of Warnowia sp., G. aureolum, and Nematodinium sp. (FJ947041). The phylogenetic trees show that the species belongs in the Gymnodinium sensu stricto clade. However, in contrast to Gymnodinium spp., cells lack nuclear envelope chambers and a nuclear fibrous connective. Unlike Polykrikos spp., cells of which possess a taeniocyst-nematocyst complex, G. shiwhaense has nematocysts but lacks taeniocysts. It differs from Paragymnodinium shiwhaense Kang, Jeong, Moestrup & Shin by possessing nematocysts with stylets and filaments. Gyrodiniellum shiwhaense n. gen., n. sp. furthermore lacks ocelloids, in contrast to Warnowia spp., Nematodinium spp., and Proterythropsis spp. Based on morphological and molecular data, we suggest that the taxon represents a new species within a new genus.

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 59:257-272 (2010) - DOI: https://doi.org/10.3354/ame01401 Ecology of Gymnodinium aureolum. II. Predation by common heterotrophic dinoflagellates and a ciliate Yeong Du Yoo1, Hae Jin Jeong1,*, Nam Seon Kang1, Jae Seong Kim2, Tae Hoon Kim3, Eun Young Yoon1 1School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul 151-747, Republic of Korea 2Red Tide Research Center, Kunsan National University, Kunsan 573-701, Republic of Korea 3Department of Oceanography, Kunsan National University, Kunsan 573-701, Republic of Korea *Email: hjjeong@snu.ac.kr ABSTRACT: We investigated whether the common heterotrophic dinoflagellates Gyrodinium dominans, Oxyrrhis marina, Pfiesteria piscicida, Polykrikos kofoidii, Protoperidinium bipes and Stoeckeria algicida, and the naked ciliate Strombidinopsis sp., were able to feed on the mixotrophic red-tide dinoflagellate Gymnodinium aureolum (GenBank accession no. FN392226). We also measured the growth and ingestion rates of G. dominans, O. marina, P. kofoidii, and Strombidinopsis sp. on G. aureolum as a function of prey concentration. We calculated grazing coefficients by combining field data on abundance of small Gyrodinium spp. (25 to 35 µm in cell length) and Strombidinopsis spp. (>70 µm) and co-occurring G. aureolum with laboratory data on ingestion rates obtained in this study. G. dominans, O. marina, P. kofoidii, and Strombidinopsis sp. were able to feed on G. aureolum, whereas P. piscicida, P. bipes, and S. algicida were not. The maximum growth rates of G. dominans, O. marina, Strombidinopsis sp. and P. kofoidii on G. aureolum were 0.92, 0.71, 0.44 and 0.11 d–1, respectively. However, the maximum ingestion rates of G. dominans on G. aureolum (2.0 ng C predator–1 d–1) were comparable with that of P. kofoidii (2.3 ng C predator–1 d–1), but much lower than that of Strombidinopsis sp. (69.7 ng C predator–1 d–1). Calculated grazing coefficients for small heterotrophic Gyrodinium spp. and large Strombidinopsis spp. on G. aureolum were up to 0.40 d–1 and 0.25 d–1, respectively (i.e. up to 33 and 22% of G. aureolum populations were removed by small Gyrodinium and Strombidinopsis populations in 1 d, respectively). The results of the present study suggest that small Gyrodinium spp. and Strombidinopsis sp. sometimes have considerable grazing effect on populations of G. aureolum. KEY WORDS: Graze · Growth · Harmful algal bloom · Ingestion · Protist · Red tide Full text in pdf format PreviousNextCite this article as: Yoo YD, Jeong HJ, Kang NS, Kim JS, Kim TH, Yoon EY (2010) Ecology of Gymnodinium aureolum. II. Predation by common heterotrophic dinoflagellates and a ciliate. Aquat Microb Ecol 59:257-272. https://doi.org/10.3354/ame01401 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 59, No. 3. Online publication date: April 21, 2010 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2010 Inter-Research.

A bloom-forming dinoflagellate was isolated from coastal waters in western Korea during a red tide event in March 2008 and clonal cultures were established. The dinoflagellate was identified as Gymnodinium aureolum based on morphological and genetic analyses (GenBank accession no. FN392226). We report here for the first time that the red-tide dinoflagellate G. aureolum, which has previously been thought to be exclusively autotrophic, is a mixotrophic species. G. aureolum fed on algal prey using a peduncle. Among the algal prey provided, G. aureolum ingested heterotrophic bacteria, the cyanobacterium Synechococcus sp., and small algal species that had equivalent spherical diameters (ESDs) of ≤11.5 μm. However, it did not feed on larger algal species (ESD ≥12 μm) or the small diatom Skeletonema costatum. The specific growth rates for G. aureolum on the cryptophyte Teleaulax sp. increased continuously with increasing mean prey concentration before saturating at prey concentrations of ca. 190 ng C ml -1 (11050 cells ml -1 ). The maximum specific growth rate (mixotrophic growth) of G. aureolum on Teleaulax sp. was 0.169 d -1 , at 20°C under a 14:10 h light:dark cycle of 20 μE m -2 s -1 , while its growth rate (phototrophic growth) under the same light conditions without added prey was 0.120 d -1 . The maximum ingestion and clearance rates of G. aureolum on Teleaulax sp. were 0.058 ng C grazer -1 d -1 (3.4 cells grazer -1 d -1 ) and 0.003 μl grazer -1 h -1 , respectively. The calculated in situ grazing coefficient for G. aureolum on co-occurring cryptophytes ranged up to 0.498 d -1 . Bioassay results indicated that this strain of G. aureolum is not toxic. Results of the present study suggest that G. aureolum has a potentially considerable grazing impact on algal populations.

The mixotrophic dinoflagellate Paragymnodinium shiwhaense n. gen., n. sp. is described from living cells and from cells prepared by light, scanning electron, and transmission electron microscopy. In addition, sequences of the small subunit (SSU) and large subunit (LSU) rDNA and photosynthetic pigments are reported. The episome is conical, while the hyposome is hemispherical. Cells are covered with polygonal amphiesmal vesicles arranged in 16 rows and containing a very thin plate-like component. There is neither an apical groove nor apical line of narrow plates. Instead, there is a sulcal extension-like furrow. The cingulum is as wide as 0.2-0.3 x cell length and displaced by 0.2-0.3 x cell length. Cell length and width of live cells fed Amphidinium carterae were 8.4-19.3 and 6.1-16.0 microm, respectively. Paragymnodinium shiwhaense does not have a nuclear envelope chamber nor a nuclear fibrous connective (NFC). Cells contain chloroplasts, nematocysts, trichocysts, and peduncle, though eyespots, pyrenoids, and pusules are absent. The main accessory pigment is peridinin. The sequence of the SSU rDNA of this dinoflagellate (GenBank AM408889) is 4% different from that of Gymnodinium aureolum, Lepidodinium viride, and Gymnodinium catenatum, the three closest species, while the LSU rDNA was 17-18% different from that of G. catenatum, Lepidodinium chlorophorum, and Gymnodinium nolleri. The phylogenetic trees show that this dinoflagellate belongs within the Gymnodinium sensu stricto clade. However, in contrast to Gymnodinium spp., cells lack nuclear envelope chambers, NFC, and an apical groove. Unlike Polykrikos spp., which have a taeniocyst-nematocyst complex, P. shiwhaense has nematocysts without taeniocysts. In addition, P. shiwhaense does not have ocelloids in contrast to Warnowia spp. and Nematodinium spp. Therefore, based on morphological and molecular analyses, we suggest that this taxon is a new species, also within a new genus.

Cultures of four strains of the dinoflagellate Gymnodinium aureolum (Hulburt) G. Hansen were established from the Elizabeth River, a tidal tributary of the Chesapeake Bay, USA. Light microscopy, scanning electron microscopy, nuclear-encoded large sub-unit rDNA sequencing, and culturing observations were conducted to further characterize this species. Observations of morphology included: a multiple structured apical groove; a peduncle located between the emerging points of the two flagella; pentagonal and hexagonal vesicles on the amphiesma; production and germination of resting cysts; variation in the location of the nucleus within the center of the cell; a longitudinal ventral concavity; and considerable variation in cell width/length and overall cell size. A fish bioassay using juvenile sheepshead minnows detected no ichthyotoxicity from any of the strains over a 48-h period. Molecular analysis confirmed the dinoflagellate was conspecific with G. aureolum strains from around the world, and formed a cluster along with several other Gymnodinium species. Morphological evidence suggests that further research is necessary to examine the relationship between G. aureolum and a possibly closely related species Gymnodinium maguelonnense.

Brevetoxins produced by the marine dinoflagellate Karenia brevis (C. C. Davis) G. Hansen et Moestrup cause neurotoxic shellfish poisoning (NSP) in human consumers and also endanger a variety of coastal wildlife. In the eastern Gulf of Mexico the presence and abundance of this species have traditionally been monitored using light microscopy (LM) observations of whole water samples. Various molecular probe methods now enable detection of multiple species from a single sample, allowing rapid sample analysis. We describe the development of sandwich hybridization assays (SHAs) for Karenia brevis, K. selliformis Haywood, Steid. et L. MacK., K. mikimotoi (Miyake et Kominami ex M. Oda) G. Hansen et Moestrup, K. papilionacea Haywood et Steid., the Karlotoxin‐producer Karlodinium veneficum (D. Ballant.) J. Larsen (=K. micrum), and Gymnodinium aureolum (Hulburt) G. Hansen, comb. nov. The assays require no nucleic acid purification and use LSU rRNA‐targeted probes and a semiautomated, 96‐well plate format. Probes tested in matrix format were specific relative to rRNAs of all nontarget species used. The response of the SHA for a constant number of K. brevis cells per unit volume of homogenate depended on the growth status of a culture, decreasing for senescent cells relative to actively growing cells. The results of preliminary field tests of the K. brevis SHA indicated that cells collected from natural populations tended to return a lower signal than those harvested from laboratory cultures, but these results are nonetheless very encouraging. These preliminary field studies show that robust standards are required for cell identification and enumeration, with which new methods can be compared.

SUMMARY The green dinoflagellate Gymnodinium chlorophorum (BAH ME 100, the type culture) was reexamined with emphasis on the structure of the flagellar apparatus and nuclear envelope. Like other Gymnodinium species, G. chlorophorum possessed a nuclear fibrous connective linking the flagellar apparatus and the nucleus, albeit in a very reduced and unique form. Microtubules nucleated from the R3 flagellar root associated with the nuclear fibrous connective and terminated at the nucleus, a novel arrangement not known in any other dinoflagellate. Although overlooked by previous researchers, nuclear chambers were present in G. chlorophorum similar to those reported in Gymnodinium aureolum and Gymnodinium nolleri. In contrast to the type species of Gymnodinium, Gymnodinium fuscum, only one nuclear pore was present per chamber. The presence of a feeding tube (peduncle) suggests that G. chlorophorum is mixotrophic. Although the fine structure of G. chlorophorum revealed its affiliation to the Gymnodinium group the above discrepancies set it apart, indicating that it might belong in a different genus.

Examination of the ultrastucture of the unarmored dinoflagellate Gymnodinium aureolum (Hulburt) G. Hansen (syn: Gyrodinium aureolum Hulburt) revealed the presence of nuclear chambers, which are specialized differentiations of the nuclear envelope, similar to those described in the type species of Gymnodinium, G. fuscum (Ehrenberg) Stein and certain other Gymnodinium species. The nuclear pores were restricted to these chambers. In the flagellar apparatus a nuclear fibrous connective linked the longitudinal microtubular root and the nucleus. This structure had so far been observed only in Gymnodinium spp. and in the heterotrophic species Actiniscus pentasterias (Ehrenberg) Ehrenberg, Nematodinium armatum (Dogiel) Kofoid et Swezy and Polykrikos kofoidii Chatton. Another unusual feature of G. aureolum was the presence of a striated fiber in the longitudinal flagellum, a feature previously only found in Ceratium furca (Ehrenberg) Claparède et Lachmann and C. tripos (O.F. Müller) Nitzsch. Gymnodinium aureolum also possessed a prominent ventral protrusion associated with the peduncle and containing electron opaque material. It is concluded that G. aureolum belongs to the Gymnodinium sensu stricto group. This may be a temporary classification, however, because G. aureolum and its allies differ from the type species G. fuscum by the presence of a transverse striated root, striated collars, trichocysts, and a peduncle.

Light and electron microscopy, nuclear‐encoded LSU rDNA sequences, and pigment analyses were performed on five geographically separate isolates ofGymnodinium mikimotoi.The morphological variation between the isolates equals that found within the isolates. The nuclear‐encoded LSU rDNA sequences were nearly identical in all isolates, and molecular analyses using maximum likelihood, parsimony, and neighbor joining showed the geographical isolates as an unresolved clade. Based on the available data it is concluded that the European isolates, formerly identified asGyrodinium aureolum,Gyrodiniumcf.aureolum, orGymnodiniumcf.nagasakiense, are conspecific with the JapaneseGymnodinium mikimotoi.An isolate from the Pettaquamscutt River, USA, is suggested to represent whatHulburt (1957)described asGyrodinium aureolum.The LSU rDNA sequence data and ultrastructural characters in this isolate closely resemble those ofGymnodinium fuscum, the type species ofGymnodinium, andGyrodinium aureolumHulburt is therefore renamedGymnodinium aureolum(Hulburt) G. Hansen, comb. nov.