Abstract Introduction: The brackish lagoons are ecosystems with great diversity and possibilities for human use. Therefore, the knowledge about phytoplankton needs to be improved to understand its real impact. Objective: To relate the Mandinga’s Lagoon phytoplankton to the limnological conditions during the dry and wet seasons. Methods: The material was collected in three stations: Isla Conchas (ICO), Mandinga Chica (MCH) and Isla del Amor (IA) during the dry (March 2018) and wet (September 2017 and 2018) seasons. The limnological analysis included ten abiotic variables, and the phytoplankton was analyzed by the Utermöhl method. Data was analyzed with the Shannon index (H') and Canonical Correspondence Analysis (CCA). Results: 136 species were identified: 68.4 % Heterokontophyta, 22.8 % Dinoflagellata, and 5.9 % Cyanobacteria; with 40 euryhaline and 96 stenohaline. The most abundant species were: Bacillaria paxillifera, Chaetoceros compressus, Coscinodiscus rothii, and Chaetoceros atlanticus. The highest abundance was in ICO (dry) and the lowest in MCH (wet), with 307 x 103 and 76 x 103 cells/ml, respectively; the H' ranged from 1.31 to 0.70 bits/ind. The CCA showed a relationship between salinity and dissolved oxygen with C. rothii and Ceratoneis closterium. The phosphates were associated with B. paxillifera, C. atlanticus, and Podosira stelligera. The nitrate, water temperature and pH were related to Tripos hircus, T. furca, Diploneis bombus, and Merismopedia elegans. In contrast, Skeletonema costatum, Cocconeis scutelum, and Nitzschia bicapitata did not correlate with the limnological variables. Conclusions: The Mandinga’s Lagoon is a shallow, euryhaline and well-oxygenated ecosystem. The dominance of diatoms and dinoflagellates was evidenced by their ability to survive in different salinities and temperatures. It is recommended monitor phytoplankton, in particular Microcystis wesenbergii, B. quinquecornis, Pseudo-nitzschia cf. pungens, and P. cf. pseudodelicatissima as they are harmful algae.

Resumen Introducción: Las lagunas salobres son ecosistemas de alta diversidad y con posibilidades para uso humano. Por lo que es necesario mejorar el conocimiento del fitoplancton para entender su impacto real. Objetivo: Relacionar el fitoplancton de la Laguna Mandinga con las condiciones limnológicas durante épocas de secas y lluvias. Métodos: El material se recolectó en tres estaciones: Isla Conchas (ICO), Mandinga Chica (MCH) e Isla del Amor (IA) en secas (marzo 2018) y lluvias (septiembre 2017 y 2018). El análisis limnológico incluyó diez variables abióticas, además del fitoplancton mediante el método de Utermöhl. Los datos fueron analizados por el índice de Shannon (H') y Correspondencia Canónica (ACC). Resultados: Análisis de 136 especies; 68.4 % Heterokontophyta, 22.8 % Dinoflagellata, 5.9 % Cyanobacteria; con 40 eurihalinas y 96 estenohalinas. Las especies más abundantes fueron: Bacillaria paxillifera, Chaetoceros compressus, Coscinodiscus rothii y Chaetoceros atlanticus. La mayor abundancia se registró en ICO (secas) y la menor en MCH (lluvias) con 307 x 103 y 76 x 103 cell/ml, respectivamente. El H' osciló entre 1.31 y 0.70 bits/ind. El CCA mostró una relación entre salinidad y oxígeno disuelto con C. rothii y Ceratoneis closterium. Los fosfatos se asociaron con B. paxillifera, C. atlanticus y Podosira stelligera. Los nitratos, temperatura y pH se correlacionaron con Tripos hircus, T. furca, Diploneis bombus y Merismopedia elegans. Mientras, Skeletonema costatum, Cocconeis scutelum y Nitzschia bicapitata no presentaron correlación con las variables limnológicas. Conclusiones: La Laguna Mandinga es un ecosistema somero, eurihalino y bien oxigenado. La dominancia de diatomeas y dinoflagelados se evidenció por su capacidad para sobrevivir en diferentes concentraciones de salinidad y temperatura. Sugerimos monitorear al fitoplancton por la presencia de Microcystis wesenbergii, B. quinquecornis, Pseudo-nitzschia cf. pungens y P. cf. pseudodelicatissima ya que pueden formar proliferaciones dañinas.

Abstract Introduction: Bio bays in Puerto Rico play an important socio-economic role and declines in dominant bioluminescent dinoflagellate Pyrodinium bahamense are concerning. Studies show erratic blooms with is weak correlation to in situ environmental factors. Our study examines shorter field and longer proxy records on dinoflagellate density at Laguna Grande de Fajardo (LGF). Objectives: To quantify temporal changes in dinoflagellate density in a long-term monitoring study, understand how the marine environment modulates those changes, and determine the wider impacts of a fluctuating climate and extreme events on proxies for dinoflagellate density. Methods: Bimonthly samples were collected from 2016 to 2021 at three sampling sites in LGF. Dinoflagellates density was estimated by Sedgewick Rafter counting cells. Environmental conditions were obtained from Rio Fajardo 5007100 station and NOAA buoy 41056. Marine climate and biotic proxies were obtained from remote sensing measurements. Kruskal Wallis, Spearman correlations and cross-correlations in the shorter field and longer proxy records were used to evaluate environmental controls on LGF dinoflagellate blooms. Results: Six years of field monitoring densities found a low period in 2016-2017, frequent and intense blooms in 2018-2021 punctuated by hurricanes. Generally low values were recorded in late winter in contrast with higher values in late summer (Aug-Nov). Light winds and mixed layer response to seasonal warming in the form of high tides and low salinity, were found to sustain dinoflagellate reproduction. Conclusions: Bioluminescent dinoflagellates are vital to coastal tourism and require resource management. LGF results show that: 1) dinoflagellate counts fluctuate widely, 2) fluorescing dinoflagellates are sensitive to environmental conditions because of limited seasonality and narrow physiological range, 3) hurricanes play a role by ‘raking and refreshing’ the coastal lagoon for subsequent biotic reproduction, and 4) intra-seasonal fluctuations of density and proxies relate to air-sea thermodynamic conditions, the salinity budget and sea level.

Resumen Introducción: Las bahías bioluminiscentes en Puerto Rico desempeñan un papel socioeconómico importante y disminuciones del dinoflagelado bioluminiscente dominante Pyrodinium bahamense son preocupantes. Los estudios muestran proliferaciones erráticas débilmente correlacionadas con factores ambientales locales. Objetivos: Cuantificar cambios en la densidad de dinoflagelados a largo plazo en la Laguna Grande de Fajardo (LGF), comprender cómo el ambiente marino modula esos cambios y determinar los impactos de eventos climáticos extremos en la densidad de dinoflagelados. Métodos: Se recolectaron muestras bimestrales del 2016-2021 en tres sitios de la LGF. La densidad se estimó mediante el conteo de células de Sedgewick Rafter. Condiciones ambientales se obtuvieron de la estación Río Fajardo 5007100 y de la boya NOAA 41056. El clima marino y los indicadores bióticos se obtuvieron por mediciones de teledetección. Se utilizaron correlaciones Kruskal Wallis, Spearman y las correlaciones cruzadas en los registros de campo corto y proxy largos para evaluar los controles ambientales en las proliferaciones de dinoflagelados LGF. Resultados: En seis años de monitoreo se encontraron densidades bajas entre el 2016-2017 y proliferaciones frecuentes e intensas en 2018-2021 marcadas por huracanes. Se registraron valores bajos a finales del invierno, en contraste con valores más altos a finales del verano (agosto-noviembre). Vientos ligeros y la respuesta de capas mixtas al calentamiento estacional en forma de mareas altas y baja salinidad, mantienen la reproducción de los dinoflagelados. Conclusiones: Los dinoflagelados bioluminiscentes son vitales para el turismo costero y requieren manejo de los recursos. En general: 1) los recuentos de dinoflagelados fluctúan ampliamente, 2) los dinoflagelados fluorescentes son sensibles a las condiciones ambientales debido a su estacionalidad limitada y estrecho rango fisiológico, 3) los huracanes juegan un rol de rastrillar y refrescar la laguna costera para su posterior reproducción, y 4) fluctuaciones intra-estacionales se relacionan con las condiciones termodinámicas aire-mar, el balance de salinidad y el nivel del mar.

Abstract The Guadalupe Island Biosphere Reserve (RBIG) is located 241 km from Mexico's western coast and is thus one of the most distant island territories in the country. Therefore, studying its biodiversity is of great interest in a biogeographic context. This study aimed to present the first records of dinoflagellates found in the RNIG. Thirty-four dinoflagellate species and infraspecific taxa were reported and illustrated. All species have been previously recorded in Mexican coastal waters, and two of them, Dinophysis tripos and Phalacroma mitra, have been reported in the literature as toxin producers. This study represents the first contribution to the knowledge of dinoflagellates in the RBIG.

Resumen La Reserva de la Biosfera Isla Guadalupe (RBIG) se localiza a 241 km de la costa occidental de México, siendo uno de los territorios insulares más distante del país. Por lo tanto, el estudio de su biodiversidad en el contexto biogeográfico resulta de gran interés. El objetivo del presente estudio fue presentar los primeros registros de dinoflagelados de la RBIG. Se enlistan e ilustran 34 especies y taxones infraespecíficos de dinoflagelados. Todas las especies ya han sido registradas para las aguas costeras mexicanas y dos de ellas, Dinophysis tripos y Phalacroma mitra, se han reportado en la literatura, como productoras de toxinas. Este estudio representa el primer aporte al conocimiento de los dinoflagelados de la RBIG.

Resumen Se registra por primera vez el género de dinoflagelado Metadinophysis (Dinophyceae: Dinophysales) en la bahía de Buenaventura y el Parque Nacional Natural Uramba- PNN Uramba en Bahía Málaga del Pacífico colombiano central, se analiza su densidad con los cambios de marea. Se registraron células con contorno subtriangular y reniforme en vista ventral, epiteca pequeña. Aleta sulcal izquierda con tres costillas y la derecha muy reducida o ausente, presentando tamaño promedio 43.1 μm de longitud total y 25.0 𝜇m de ancho total, la densidad del género se analizó bajo cuatro factores, la marea alta y la marea baja en la bahía de Buenaventura y en la bahía de Málaga. Se encontraron diferencias significativas entre la densidad en la marea alta y la marea baja para la bahía de Buenaventura, la diferencia entre la marea alta de la bahía de Málaga y la marea baja de la bahía de Buenaventura. Asimismo, se estableció que la distribución de la densidad no tiene ninguna estructura espacial en ninguno de los eventos mareales. Con el presente estudio se registra por primera vez el género de Metadinophysis en el pacífico colombiano, ampliando su distribución a nivel global.

Abstract The dinoflagellate genus Metadinophysis (Dinophyceae Dinophysales) is recorded for the first time in the Buenaventura Bay and Uramba National Natural Park-PNN Uramba in Málaga Bay in the central Colombian Pacific and its density is analyzed with tidal changes. Cells were recorded with subtriangular and reniform outline in ventral view and small epitheca. Left sulcal fin with three ribs and the right one very reduced or absent, presenting average size 43.1 μm total length and 25.0 μm total width, the density of the genus was analyzed under four factors, high tide and low tide in Buenaventura Bay and in Málaga Bay; significant differences were found between the density at high tide and low tide for Buenaventura Bay, the difference between high tide in Malaga Bay and low tide in Buenaventura Bay. Likewise, it was established that the density distribution has no spatial structure in any of the tidal events. With the present study, the genus Metadinophysis is recorded for the first time in the Colombian Pacific, extending its distribution globally.

Abstract Despite its small area, Araçá Bay (AB) holds cultural, historical, and economic value and displays great benthic biodiversity. Thus, it is crucial to monitor its environmental health, including knowing the main groups of phytoplankton and their temporal variability. The shallow waters of Araçá Bay are continuously modified by the complex hydrography of the adjacent São Sebastião channel (SSC), challenging standard experimental designs for phytoplankton collection. Here we report changes in phytoplankton composition at intervals of five to six weeks from September 2013 to August 2014 in both Araçá Bay and SSC. Samples were collected twice daily for three consecutive days to increase taxonomic resolution. Our goal was to provide an inventory of species occurrences to aid future public policies and environmental management of the area. Analyses revealed high species richness and 166 different phytoplankton taxa. Diatoms and dinoflagellates were always numerically dominant, but taxa occurrence changed markedly. Diatoms of the genera Pseudo-nitzschia were abundant during spring and summer concurrently to signatures of South Atlantic Central Water in the SSC, while Thalassiosira occurred when waters displayed relatively lower salinity. The inventory demonstrated several potentially harmful species of microalgae and cyanobacteria, strongly suggesting investments in monitoring programs in this area that currently experience an increase in population. AB (AB cultural historical biodiversity Thus health variability SSC , (SSC) collection 201 resolution 16 dominant markedly Pseudonitzschia Pseudo nitzschia salinity cyanobacteria population (SSC 20 1 2

Resumo Apesar de sua pequena área, a baía do Araçá (AB) possui grande valor cultural, histórico e econômico, e biodiversidade bentônica. Assim, é fundamental monitorar sua saúde ambiental, que inclui conhecer os principais grupos de fitoplâncton e sua variabilidade temporal. As águas rasas da baía do Araçá são continuamente modificadas pela hidrografia complexa do canal de São Sebastião (SSC), desafiando desenhos experimentais convencionais para coleta de fitoplâncton. Aqui relatamos mudanças sazonais na composição do fitoplâncton, em intervalos de 4 a 6 semanas, de setembro de 2013 a agosto de 2014 na baía do Araçá e no SSC, sendo coletadas duas vezes ao dia por três dias consecutivos em cada campanha de amostragem para aumentar a resolução taxonômica. Nosso objetivo foi fornecer um inventário de ocorrência de espécies para auxiliar futuras políticas públicas e gestão ambiental na área. As análises revelaram alta riqueza de espécies e 166 táxons fitoplanctônicos diferentes. Diatomáceas e dinoflagelados foram numericamente dominantes, mas a ocorrência de táxons mudou acentuadamente entre observações. As diatomáceas do gênero Pseudo-nitzschia foram abundantes durante a primavera e o verão concomitantemente às assinaturas da Água Central do Atlântico Sul no CSS, enquanto Thalassiosira ocorreu durante períodos de salinidade relativamente mais baixa. O inventário demonstrou várias espécies potencialmente nocivas de microalgas e cianobactérias, sugerindo fortemente investimentos para programas de monitoramento nesta área que vem registrando aumento populacional contínuo. AB (AB cultural econômico bentônica Assim temporal SSC , (SSC) semanas 201 taxonômica 16 diferentes dominantes observações Pseudonitzschia Pseudo nitzschia CSS baixa cianobactérias contínuo (SSC 20 1 2

Abstract: Background and Aims: The order Gymnodiniales is composed of 11 families, 63 genera and 641 taxonomically valid species. These dinoflagellates are characterized by having a very fragile cell wall. In addition, some species can produce phycotoxins and form dense blooms. In the case of the Mexican Pacific coast, studies focused on knowing the diversity of this group are still limited, despite the economic, social, and ecological importance of these microorganisms. Therefore, the objective of this study was to make a floristic list from a bibliographical review, integrating only the records supported by micrographs, to know the diversity of athecate dinoflagellates of the order Gymnodiniales present in the Mexican Pacific Ocean, with emphasis on those that form harmful algal blooms. Methods: The search for information was carried out in publications (articles and book chapters), from the first record (1943) to the present (November 2022). Each record was confirmed only by the existence of optical and scanning electron micrographs. Key results: The Mexican Pacific is made up of 11 coastal states, where the presence of 10 families, 31 genera and 103 species (which represents 16% of the total number of species recorded worldwide) is currently reported for the order Gymnodiniales. Of the 11 families that make up this order, the Gymnodiniaceae family grouped 29% of the total number of species recorded for the Mexican Pacific, where the genera Gymnodinium and Gyrodinium presented the largest number of species. Conclusions: The evidence presented in this study showed that there is a low diversity for this order in the Mexican Pacific, so it is necessary to implement a greater sampling effort, in addition to venturing into different molecular tools that allow obtaining a better approximation of the diversity in the Mexican coasts.

Resumen: Antecedentes y Objetivos: El orden Gymnodiniales está compuesto por 11 familias, 63 géneros y 641 especies taxonómicamente válidas. Estos dinoflagelados se caracterizan por presentar una pared celular muy frágil. Además, algunas especies pueden llegar a producir potentes toxinas e incluso tienen la capacidad para formar grandes florecimientos. Los estudios enfocados en conocer la diversidad de este grupo, en el caso de las costas del Pacífico Mexicano, siguen siendo limitados, a pesar de la importancia económica, social y ecológica de estos microorganismos. Por lo tanto, el objetivo de este estudio fue realizar un listado florístico a partir de una revisión bibliográfica, que integre únicamente a los registros respaldados por micrografías, para conocer la diversidad de dinoflagelados atecados del orden Gymnodiniales presentes en el Pacífico Mexicano, con énfasis en aquellos formadores de florecimientos algales nocivos. Métodos: La búsqueda de información se realizó en publicaciones (artículos y capítulos de libros), desde el primer registro (1943) hasta la actualidad (noviembre 2022). Cada registro fue confirmado únicamente mediante la existencia de micrografías ópticas y de electrónicas de barrido. Resultados clave: El Pacífico Mexicano está conformado por 11 estados costeros, donde actualmente se tiene reportada la presencia de 10 familias, 31 géneros y 103 especies (16% del total de las registradas a nivel mundial) para el orden Gymnodiniales. De las 11 familias que conforman a este orden, la familia Gymnodiniaceae agrupó 29% del total de especies registradas para el Pacífico Mexicano, donde los géneros Gymnodinium y Gyrodinium presentaron el mayor número de especies. Conclusiones: La evidencia presentada en este estudio demostró que existe una baja diversidad para este orden en el Pacífico Mexicano, por lo que es necesario implementar un mayor esfuerzo de muestreo, además de incursionar en diferentes herramientas moleculares que permitan obtener una mejor aproximación a la diversidad alfa en las costas mexicanas.

Resumo O presente estudo relata variações sazonais e espaciais na diversidade, na distribuição e na abundância de dinoflegelados e indica a presença de espécies de HAB nas águas do Paquistão. Um total de 179 táxons, registrados nesse estudo de águas offshore e próximas à costa, pertence a 41 gêneros em 26 famílias e 10 ordens. A alta contagem de espécies (149 espécies) foi registrada na estação offshore da Ilha de Manora (MI-1) e 105 spp., 109 spp. e 115 spp. foram encontrados na estação offshore da vila de Mubarak (MV-1), Manora perto da estação costeira (MI- 2) e estação próxima à costa da Vila de Mubarak (MV-2), respectivamente. Tripos furca foi a espécie dominante e de ocorrência frequente (> 1 x103 a > 25 x103 células L-1 da costa e > 1x 105 células Ll de estações próximas à costa), além de Alexandrium catenella menos abundante, Alexandrium sp., Alexandrium minutum e Prorocentrum micans (> 103 a 25x 103 células/L). Outras 44 espécies ocorreram em números relativamente baixos (< 103 células L-1). Setenta espécies foram encontradas durante o período de estudo em todas as quatro estações. Foi registrado um alto número de espécies em três gêneros (Tripos (38), Protoperidinium (34) e Prorocentrum (20). Potencialmente tóxicos (16 gêneros e 43 espécies) e HAB relacionados (19 gêneros e 30 espécies), táxons de dinoflagelados também foram registrados. A contribuição percentual de dinoflagelados na população fitoplanctônica total geralmente permaneceu abaixo de 20%, exceto em alguns casos. As estações da Ilha de Manora tinham índice de Shannon comparativamente mais alto e equitabilidade e índice de dominância ligeiramente mais baixos. O gráfico de PCA mostrou forte correlação positiva entre concentração de clorofila-a e oxigênio dissolvido, número total de fitoplânctons e dinoflagelados.

Abstract The present study reports on seasonal and spatial variations in diversity, distribution and abundance of dinoflegellates and indicates the presence of HAB species in Pakistan waters. A total of 179 taxa, recorded in this study from offshore and near-shore waters, belong to 41 genera in 26 families and 10 orders. The high species count (149 species) was recorded from Manora Island offshore station (MI-1) and 105 spp, 109 spp and 115 spp were encountered from the Mubarak village offshore station (MV-1), Manora near shore station (MI-2) and Mubarak Village near-shore station (MV-2) respectively. Tripos furca was the dominant and frequently occurring species (> 1 x103 to > 25 x103 cells L-1 from coastal and >1x 105 cells L-l from near-shore stations) in addition to less abundant Alexandrium catenella, Alexandrium sp., Alexandrium minutum, and Prorocentrum micans (>103 to 25x 103cells/L). Another 44 species occurred in relatively low numbers (<103 cell L-l). Seventy species were found throughout the study period at all four stations. High number of species in three genera (Tripos (38), Protoperidinium (34) and Prorocentrum (20) was recorded. Potently toxic (16 genera 43 species) and HAB related (19 genera and 30 species) dinoflagellate taxa were also recorded. The percent contribution of dinoflagellates in total phytoplankton population generally remained below 20% except for a few instances. Manora Island stations had comparatively higher Shannon index and equitability and slightly lower dominance index. The PCA plot showed strong positive correlation among chlorophyll-a concentration, dissolved oxygen, total number of phytoplankton and dinoflagellates.

Resumo Objetivo Objetivamos caracterizar a estrutura da comunidade fitoplanctônica e identificar os principais fatores ambientais que impulsionam a comunidade em cinco reservatórios construídos na região do alto rio Paraná. Métodos O fitoplâncton e as variáveis ambientais foram coletados na região lacustre do reservatório, entre novembro de 2013 e novembro de 2014, com intervalo entre as coletas de 3 a 6 meses. A riqueza e a biomassa da comunidade fitoplanctônica foram utilizadas como resposta à variabilidade ambiental espacial e temporal dos reservatórios. Os dados das variáveis ambientais foram analisados por meio de uma Análise de Componentes Principais (PCA). Foram realizadas Análises de Escalonamento Multidimensional Não-Métrico (NMDS) aos dados de riqueza e biomassa da comunidade fitoplanctônica. Resultados Identificamos 80 táxons distribuídos em 11 classes, dos quais Cyanobacteria e Chlorophyceae foram os mais representados. Não observamos variação temporal significativa para variáveis ambientais ou atributos da comunidade fitoplanctônica, o que pode estar relacionado à prolongada estiagem neste período no sudeste brasileiro. Os maiores valores de riqueza e biomassa fitoplanctônica foram encontradas em Três Irmãos (Rio Tietê), reservatório localizado na bacia mais antropizada do país. Cianobactérias e dinoflagelados dominaram a biomassa em todos os reservatórios durante o período estudado. Os reservatórios de Ilha Solteira, Jupiá e Porto Primavera apresentaram tendência de diminuição nos valores de riqueza e biomassa fitoplanctônica, sendo que os reservatórios construídos em série no rio Paraná provavelmente possuem forte interdependência, de acordo com o conceito do CRCC. Conclusões A variação espacial dos atributos fitoplanctônicos foi influenciada principalmente pela posição ocupada pelo reservatório na bacia hidrográfica, tempo de retenção de água (TR) e concentrações de nutrientes em cada reservatório.

Abstract Aim We aimed to characterize the structure of the phytoplankton community and identify the main environmental factors driving the community in five reservoirs constructed in the region of the high Paraná River. Methods The phytoplankton and environmental variables were collected at the lacustrine region of the reservoir, between November 2013 and November 2014, with interval between collections ranged from 3 to 6 months. The richness and biomass of the phytoplankton community were measured as a response to the spatial and temporal environmental variability. Data from environmental variables was analyzed by Principal Component Analysis (PCA). Non-Metric Multidimensional Scaling Analyzes (NMDS) were performed on the richness and biomass data of the phytoplankton community. Results We identified 80 taxa distributed in 11 taxonomic classes, from which Cyanobacteria and Chlorophyceae were best represented. We did not observe significant temporal variation for either environmental variables or attributes of the phytoplankton community, which may be related to the prolonged drought in this period in the Brazilian Southwest. Higher phytoplankton richness and biomass were found in the Três Irmãos (Tiete River), reservoir located in the most anthropized basin in the country. Cyanobacteria and dinoflagellates dominated the biomass in all reservoirs during the studied period. The Ilha Solteira, Jupiá and Porto Primavera reservoirs showed a tendency to decrease in the values of phytoplankton richness and biomass, and the reservoirs built in series in the Paraná River probably have strong interdependence, according to the CRCC concept. Conclusions Spatial variation in phytoplankton attributes was influenced mainly by the position occupied by the reservoir in the hydrographic basin, water retention time (RT) and nutrient concentrations in each reservoir.

Resumo Scrippsiella acuminata é um complexo de espécies que pode causar condições anóxicas na coluna d’água durante florações. Este estudo teve como objetivo analisar a ocorrência e distribuição de Scrippsiella cf. acuminata ao longo do gradiente estuarino do rio Paraguaçu, a partir de coletas bimestrais (março de 2018 a março de 2019) realizadas em 12 pontos amostrais. Variáveis ambientais foram medidas in situ, e amostras de água foram coletadas para análise de nutrientes inorgânicos dissolvidos e densidade de células fitoplanctônicas. Em cada ponto, as amostras foram coletadas para análise da composição das espécies e preservadas com formaldeído com concentração final de 4%. S. cf. acuminata ocorreu em todo o gradiente estuarino (salinidade 0,1–38,9), exceto em julho, coincidindo com as menores concentrações de nutrientes inorgânicos dissolvidos. A densidade celular variou entre 20 células L-1 (janeiro de 2019) e 1,8 × 106 células L-1 (março de 2018); neste último, ocorreu uma floração em condições de baixa salinidade (5,7) e a maior concentração de nutrientes inorgânicos dissolvidos registrada para o estudo. A densidade celular (1,7 × 105 L-1) aumentou novamente em novembro de 2018. Nenhum dos eventos teve efeitos prejudiciais no sistema estuarino. Este estudo permitiu-nos compreender melhor os padrões de distribuição de S. cf. acuminata considerando as características ambientais que podem favorecer seu desenvolvimento.

Abstract Scrippsiella acuminata is a species complex that can cause anoxic conditions in the water column during blooms. This study aimed to analyze the occurrence and distribution of Scrippsiella cf. acuminata along the estuarine gradient of Paraguaçu River, from bimonthly sampling (March 2018 to March 2019) performed at 12 sampling points. Environmental variables were measured in situ, and water samples were collected for analysis of dissolved inorganic nutrients and phytoplankton cell density. At each point, samples were collected for analysis of species composition and preserved with formaldehyde at a final concentration of 4%. S. cf. acuminata occurred throughout the estuarine gradient (salinity 0.1–38.9), except in July, coinciding with the lowest concentrations of dissolved inorganic nutrients. Cell density varied between 20 cel L-1 (January 2019) and 1.8 × 106 cell L-1 (March 2018); in the latter, the species bloomed under conditions of low salinity (5.7) and the highest dissolved inorganic nutrient concentration recorded in the study. Cell density (1.7 × 105 L-1) increased in November 2018. Neither event had any detrimental effects on the estuarine system. This study allowed us to better understand the distribution patterns of S. cf. acuminata considering the environmental characteristics that can favor its development.

Summary Background and aims : Planktonic dinoflagellates have a great ecological significance in marine environments. While some dinoflagellate species commonly reach bloom concentrations and are thus conspicuous components of marine phytoplankton, others occur in very low abundances which make them difficult to detect in field studies. Here we analyzed dinoflagellate composition and abundance in five oceanographic expeditions carried out in continental shelf and slope waters of the Argentine Sea. M&M : Plankton abundance was estimated by the Utermohl method, using inverted microscopy, whereas further optical and scanning electron microscopy was applied for the identification of dinoflagellate species. Results : We focused on the occurrence of seven dinoflagellates that have been previously poorly documented or overlooked in marine environments worldwide: Dinophysis microstrigiliformis; Gyrodinium sp.; Karlodinium elegans; Oxytoxum laticeps; Peridiniella danica; Peridiniella globosa and Prorocentrum nux. The latest and K. elegans are observed for the first time in field conditions after their original descriptions based on cell cultures. While most species were detected in low or moderate abundances, P. nux, which is the smallest Prorocentrum species, reached 82,000 cells L-1 in slope waters. Very small Gyrodinium cells (11.5 |jm long; 8.7 |jm wide) with a distribution restricted to slope waters during spring, were not possible to be accurately assigned to a species. Conclusions : This study contributes to the understanding of dinoflagellate diversity in the Argentine Sea and the worldwide distribution of little known species.

Resumen Introducción y objetivos : Los dinoflagelados planctónicos son de gran relevancia en los ecosistemas marinos. Mientras que algunas especies suelen forman floraciones y ser componentes conspicuos del fitoplancton, otras se encuentran en abundancias muy bajas, lo cual hace difícil su detección. Aquí analizamos la composición y abundancia de dinoflagelados en cinco expediciones oceanográficas realizadas en aguas de la plataforma continental y del talud del Mar Argentino. M&M : La abundancia se estimó con microscopio invertido (método Utermohl) y se utilizó microscopía óptica y electrónica de barrido para la identificación específica. Resultados : Nos enfocamos en la ocurrencia de siete dinoflagelados que previamente han sido poco documentados en ambientes marinos de todo el mundo: Dinophysis microstrigiliformis; Gyrodinium sp.; Karlodinium elegans; Oxytoxum laticeps; Peridiniella danica; Peridiniella globosa y Prorocentrum nux. Esta última especie y K. elegans se observan por primera vez en el campo desde su descripción basada en cultivos celulares. Si bien la mayoría de las especies se detectaron en abundancias bajas o moderadas, P. nux, el Prorocentrum más pequeño, alcanzó 82.000 células L-1 en aguas del talud. Células pequeñas de Gyrodinium sp. (11,5 jm de largo y 8,7 jm de ancho), con un una distribución restringida a las aguas del talud durante la primavera, no pudieron ser asignadas con precisión a nivel específico. Conclusiones : Este estudio contribuye al conocimiento de la diversidad de dinoflagelados en el Mar Argentino y la distribución mundial de especies poco conocidas.

ABSTRACT The tectonic opening of the Tasmanian Gateway and Drake Passage represented crucial geographic requirements for the Cenozoic development of the Antarctic Circumpolar Current (ACC). Particularly the tectonic complexity of Drake Passage has hampered the exact dating of the opening and deepening phases, and the consequential onset of throughflow of the ACC. One of the obstacles is putting key regional tectonic events, recorded in southern Patagonian sediments, in absolute time. For that purpose, we have collected Campanian-Eocene sediment samples from the Chilean sector of Southern Patagonia. Using U-Pb radiometric dating on zircons and dinoflagellate cyst biostratigraphy, we updated age constraints for the sedimentary formations, and the hiatuses in between. Thick sedimentary packages of shallow-marine and continental sediments were deposited in the foreland basin during the early Campanian, mid-Paleocene, the Paleocene-Eocene boundary interval and the middle Eocene, which represent phases of increased foreland subsidence. We interpret regional sedimentary hiatuses spanning the late Campanian, early-to mid-Paleocene, mid-Eocene and latest Eocene-early Oligocene to indicate times of reduced foreland subsidence, relative to sediment supply. We relate these changes to varying subduction rates and Andean orogeny. Dinoflagellate cyst assemblages suggest that the region was under the influence of the Antarctic-derived waters through the western boundary current of the Subpolar Gyre, developed in the southwest Atlantic Ocean and thus argues for limited throughflow through the Drake Passage until at least the latest Eocene. However, the proliferation of dinoflagellate endemism we record in the southwest Atlantic is coeval with that in the southwest Pacific, and on a species level, dinoflagellate cyst assemblages are the same in these two regions. This suggests that both regions were oceanographically connected throughout the early Paleogene, likely through a shallow opening of a restricted Drake Passage. This implies a continuous surface-water connection between the south Pacific and the South Atlantic throughout the late Cretaceous-early Paleogene.

RESUMEN La apertura tectónica del Conducto de Tasmania y del Pasaje de Drake implicó dos requisitos geográficos cruciales para el desarrollo de la Corriente Circumpolar Antártica (CCA) durante el Cenozoico. En particular, la complejidad tectónica del Pasaje de Drake ha dificultado la datación precisa de las fases de apertura y profundización, y el consiguiente inicio del flujo de la CCA. Uno de los problemas es poner en tiempo absoluto los eventos tectónicos regionales claves, registrados en los sedimentos del sur de la Patagonia. Para ese propósito, recolectamos muestras de sedimentos del Campaniano-Eoceno del sector chileno de la Patagonia meridional. Utilizando la datación radiométrica de U-Pb en circones y la bioestratigrafía de quistes de dinoflagelados (dinoquistes), actualizamos los límites de edades de las formaciones sedimentarias, y los hiatos entre ellas. Los espesos paquetes sedimentarios de sedimentos marinos poco profundos y continentales fueron depositados durante el Campaniano temprano, el Paleoceno medio, el límite Paleoceno-Eoceno y el Eoceno medio, que representan fases de mayor subsidencia de la cuenca. Interpretamos la existencia de hiatos sedimentarios regionales que abarcan el Campaniano tardío, el Paleoceno temprano y medio, el Eoceno medio y el Eoceno tardío-Oligoceno temprano para indicar los momentos de menor subsidencia del terreno en relación con el aporte de sedimentos. Vinculamos estos cambios con la variación de las tasas de subducción y la orogenia andina. Las asociaciones de dinoquistes sugieren que la región estaba bajo la influencia de aguas provenientes de la Antártica a través de la corriente de borde occidental del Giro Subpolar desarrollado en el Atlántico sudoccidental y, por lo tanto, argumentan a favor de un flujo limitado a través del Pasaje de Drake hasta por lo menos el Eoceno más tardío. Sin embargo, la proliferación del endemismo de dinoflagelados que registramos en el Atlántico sudoccidental es coetánea con la del Pacífico sudoccidental, y a nivel de especies, se caracterizan por las mismas asociaciones de dinoquistes. Esto sugiere que ambas regiones estaban conectadas durante el Paleógeno temprano, probablemente a través de una apertura somera en un Pasaje de Drake limitado. Esto implica una conexión continua de agua superficial entre el Pacífico Sur y el Atlántico Sur durante el Cretácico tardío-Paleógeno temprano.

Resumo Ceratium furcoides é uma espécie invasora que tem causado desequilíbrio ecológico em vários reservatórios no Brasil. Este estudo investiga os principais fatores que podem favorecer a ocorrência de florações de C. furcoides em um reservatório tropical do Nordeste do Brasil, durante um período de seca extrema. Amostras contendo fitoplâncton foram coletadas mensalmente de fevereiro a setembro de 2017. Análises quantitativas de C. furcoides foram realizadas e o volume celular estimado por meio de fórmulas geométricas. O biovolume médio de C. furcoides apresentou diferenças significativas, variando de 0,78 mm3 L-1 a 11,29 mm3 L-1 relatado em março e setembro, respectivamente. Os parâmetros ambientais apresentaram baixa oscilação ao longo do estudo, exceto a condutividade. Relações significativas entre o biovolume de C. furcoides, temperatura da água e fosfato reativo solúvel foram observadas. Os resultados relatados aqui sugerem que as condições adversas causadas por uma estação de seca não afetam negativamente esta espécie.

Abstract Ceratium furcoides is an invasive species that has caused ecological imbalance in several reservoirs in Brazil. This study investigates the main factors that may favor the occurrence of Ceratium furcoides blooms in a tropical reservoir from the Northeast Brazil, during an extreme drought season. Samples containing phytoplankton were collected monthly from February to September 2017. Quantitative analysis of C. furcoides was performed and the cell volume was estimated using geometric formulas. Mean biovolume of C. furcoides showed significant differences, ranging from 0.78 mm3 L-1 to 11.29 mm3 L-1 reported in March and September, respectively. Environmental parameters presented low oscillation throughout the study, except the conductivity. Significant relationships among the C. furcoides biovolume, water temperature and soluble reactive phosphate were observed. The findings reported here suggest that adverse conditions caused by a drought season did not negatively affect this species.

Abstract The genus Blepharocysta Ehrenberg currently comprises 5 species of truly marine planktonic thecate dinoflagellates, which are solitary, globose, subspherical and heterotrophic cells, lack typical depressed cingulum and sulcus, and are mainly distributed in tropical areas. The morphology of 2 species, Blepharocysta splendor-maris and B. paulsenii, found in net samples from the tropical Mexican Pacific, was studied by LM and SEM, especially plate arrangement and theca ornamentation. Blepharocysta splendor-maris showed more ovoid cells, developed sulcal lists, and theca with shallow poroids having a relative low density, whereas B. paulsenii had more spherical cells, shorter epitheca, reduced and slightly ornamented sulcal lists, and theca with deep poroids having a relatively higher density. The thecal tabulation in both species agrees with conventional tabulation, including the anterior intercalary plate in B. paulsenii. A comparison of both morphological and ecological characteristics among all species of the genus is done, outstanding shape of cells, relative size, development of sulcal lists, and especially the theca ornamentation as important morphological characters to distinguish species. Blepharocysta splendor-maris is the only species distributed from tropical to Antarctic waters, whereas the others are limited to tropical and subtropical waters.

Resumen El género Blepharocysta Ehrenberg comprende 5 especies de dinoflagelados tecados, planctónicos marinos. Incluye células solitarias, globulares, subesféricas y heterótrofas, que carecen de cingulum y sulcus típicos, de distribución principal en áreas tropicales. Se estudió la morfología de las especies Blepharocysta splendor-maris y B. paulsenii, encontradas en muestras de red del Pacífico mexicano tropical, usando ML y MEB, particularmente el arreglo de placas y ornamentación de la teca. Blepharocysta splendor-maris mostró una forma ovoide, aletas sulcales desarrolladas, teca con poroides poco profundos y mediana densidad, mientras que B. paulsenii tuvo forma más esférica, epiteca más corta, aletas sulcales reducidas, ligeramente ornamentadas y teca con poroides profundos, de mayor densidad. La tabulación de placas en ambas especies concuerda con la tabulación convencional, incluida la placa intercalar anterior en B. paulsenii. Se comparan las características morfológicas y ecológicas de las especies del género, destacando forma de células, tamaño relativo, desarrollo de las aletas sulcales y especialmente la ornamentación de la teca como caracteres morfológicos para distinguir especies. Blepharocysta splendor-maris es la única especie distribuida desde aguas tropicales a antárticas, mientras que las otras están limitadas a aguas tropicales y subtropicales.

Abstract Harmful algal blooms are an increasingly common problem worldwide, causing severe damage to public health, economic losses in aquaculture, damage to tourism and mortality events of natural populations of fish, birds and marine mammals. The toxins are produced by phytoplankton and accumulated in bivalve molluscs that feed on water filtration, being these main vectors of human intoxication. In the Argentine Sea marine toxins of microalgal origin have been reported associated with four shellfish poisoning syn-dromes. The most serious due to their extension, frequency, toxicity and affected organisms are those caused by the dinoflagellate Alexandrium catenella responsible for the Paralytic shellfish poisoning that has caused numerous human deaths. Then, the mildest, in severity and frequency, is the Diarrhetic shellfish poisoning. In contrast, domoic acid, known as Amnesic shellfish toxin, has not produced human intoxications yet. Recently, toxins and dinoflagellate species causing Azaspiracid shellfish poisoning have been re-corded, expanding the range of toxins for the region. In addition, the potentially toxic Yessotoxins and Spirolides have been detected, whose mechanism of action and toxicity is still being evaluated worldwide. These emerging toxins represent a potential risk to public health and socioeconomic activities due to the eventual closure of mollusc exploitation sites. They certainly present a new challenge, since detection and quantification can only be carried out using methods based on HPLC - mass spectrometry, which makes monitor-ing in regional laboratories difficult. Prevention through policies, regulations, and monitoring and control systems of each toxin group is the key management tool. These preventive measures are expected to contribute to reducing the number of poisonings and to ap-plying more efficient fisheries closures, ensuring a balance that protects both public health and the development of the fishing industry.

Resumen Las floraciones de algas nocivas son un problema cada vez más frecuente a nivel mundial que ocasiona severos daños sobre la salud pública, pérdidas económicas en acuicultura, perjuicios al turismo y episodios de mortalidad de poblaciones naturales de peces, aves y mamíferos marinos. Las toxinas son producidas por el fitoplancton y se acumulan en moluscos bivalvos que se alimentan por filtración del agua siendo estos los principales vectores de intoxicación humana. En el Mar Argentino, se han reportado toxinas marinas de origen microalgal asociadas con cuatro síndromes de intoxicación por moluscos. Los síndromes más graves por su extensión, frecuencia, toxicidad y organismos afectados, son los originados por el dinoflagelado Alexandrium cate-nella responsable de la Intoxicación Paralizante por Moluscos la cual ha ocasionado numerosas muertes humanas. Seguidamente, la más leve, en cuanto a gravedad y frecuencia, ha sido la Intoxicación Diarreica por Moluscos. En contraste, el ácido domoico, conocido como toxina amnésica de moluscos, no ha producido hasta ahora intoxicaciones humanas. Recientemente, se amplió el rango de toxinas para la región al registrarse las toxinas y los dinoflagelados productores de la Intoxicación Azaspirácidos por Moluscos. Además, se han detectado las potencialmente tóxicas Yessotoxinas y Espirolidos, cuyos mecanismos de acción y toxicidad están siendo aún evaluados a nivel mundial. Estas toxinas emergentes para la región, representan un riesgo potencial para la salud e inconvenientes socioeconómicos por el cierre de los sitios de explotación de moluscos. Ciertamente presentan un nuevo desafío, pues la detección y cuantificación sólo puede realizarse por medio de métodos basados en HPLC - espectrometría de masas, lo cual dificulta el monitoreo en laboratorios regionales en el país. La herramienta clave de manejo es la prevención, a través de políticas, regulaciones y sistemas de monitoreo y control de cada grupo de toxinas. A través de estas mejoras, se anticipa que no sólo disminuirá el número de afectados por estas intoxicaciones, si no que se podrán realizar vedas más eficientes, asegurando un equilibrio que proteja tanto la salud pública como el desarrollo de la industria pesquera.

Abstract: In this work 10 years of data (1986-1996) from a fixed station located in the northern part of Valparaíso Bay (33º00’S; 71º35’W) were analysed to study the influence of coastal upwelling activity on the temporal variation of micro-phytoplankton (20-200 μm) and their relationship with oceanographic conditions. The upwelling activity at the bay was associated to semi-annual wind regime with an intensification of upwelling-favourable S-SW winds from September to March followed by a decrease and the occurrence of downwelling events from April to August. Oceanographic conditions showed the ascent of cold, nutrient-rich salty water in spring (September-November). However, during summertime under highest upwelling index, thermal stratification conditions were registered. This stratification might be associated to either the solar radiation or the presence of an upwelling shadow area in the bay. The upwelling period had the highest micro-phytoplankton abundance mainly dominated by diatoms. This period was associated with an increase in biomass and richness in the bay. Meanwhile during non-upwelling period -under homogenous conditions of temperature, salinity and nutrients- an increase in diversity (but low abundance and richness) associated to dinoflagellates and silicoflagellates was noted. Therefore, the results suggest the presence of a bi-modal regime of micro-phytoplankton in the bay in response to changes in oceanographic conditions related to local wind forcing and mixing/stratification.

Resumen: Se analizaron 10 años de datos (1986-1996) registrados en una estación fija ubicada al norte de la bahía de Valparaíso (33º00’S; 71º35’O), con el objetivo de estudiar la influencia de la surgencia costera en la variación temporal del micro-fitoplancton (20-200 μm) y su relación con las condiciones oceanográficas. La surgencia costera mostró un régimen bi-modal asociado al viento, con dominio de vientos S-SO favorables a la surgencia entre septiembre y marzo, seguido de una disminución en la intensidad del viento y un debilitamiento de la surgencia entre abril y agosto. Las condiciones oceanográficas mostraron el afloramiento de agua fría y salada, con alto contenido de nutrientes en primavera (septiembre-noviembre). Sin embargo, en verano bajo intensa surgencia se registraron condiciones de estratificación térmica. Esta estratificación podría asociarse tanto a la radiación solar como a la presencia de un área de sombra de surgencia en la bahía. El periodo de surgencia activa presentó el máximo en la abundancia del micro-fitoplancton, dominado por las diatomeas. Este periodo también se asoció con un aumento en la biomasa y la riqueza del micro-fitoplancton. Durante el periodo de debilitamiento de la surgencia -bajo condiciones homogéneas de temperatura, salinidad y nutrientes- se registró un incremento en diversidad (pero baja abundancia y riqueza) asociado al aumento de dinoflagelados y silicoflagelados. Los resultados muestran un régimen bi-modal del micro-fitoplancton en la bahía en respuesta a los cambios en las condiciones oceanográficas relacionados con el forzante local del viento y las condiciones de mezcla/estratificación.