Spatio-temporal Distribution and Biochemical Composition of Phytoplankton along the Coastal Waters of Dakshin Kannada District, Karnataka, India

The phytoplankton distribution and biochemical composition concerning water quality parameters were studied in the coastal waters off Mangalore, Monthly sampling was carried out from October 2020 to May 2022 at selected stations of Netravathi-Gurupura estuary, latitude 12°50'38.56" N, longitude 74°50'0.23° to coastal waters off Padubidri latitude 13° 8'0. 57" N longitude 74°42'9.47° with an average depth of 8 meters. Spatiotemporally the phytoplankton, chlorophyll-a and phytoplankton biochemical composition showed a significant difference for the entire duration. During the present investigation, 35 different phytoplankton genera belonging to 3 groups were observed with complete domination from diatoms with 27 genera followed by Dinoflagellates 7 and blue-green algae. distribution and abundance of the phytoplankton were mainly Chaetoceros sp., Ceratium sp., Thallasiocera sp., Biddulphia sp., Coscinodiscus sp., Rhizosolenia sp., Ditylum sp., Triceratium sp., Nitzschia sp. and blue-green algae under Chrysophyta, Bryophyta, Chlorophyta, Cyanophyta were observed, while in biochemical composition of phytoplankton, the carbon contributed to the highest percentage and hydrogen constitute to the lowest percentage. Crude protein and Lipid contents are maximum during post-monsoon and carbohydrates showed their highest content during pre-monsoon for phytoplankton. There is a direct relationship between the biochemical composition and the physiochemical and environmental conditions including nutrients, especially nitrates and phosphates.

OCCURRENCE OF PHYTOPLANKTON OF SOME ESTUARIES FROM RATNAGIRI DISTRICT DURING RAINY SEASON

Occurrence, diversity and density of phytoplankton were recorded in five estuaries from Ratnagiri district of Maharashtra during rainy season. A total of 104 phytoplankton species belonging four division, viz, Cyanophyceae (11), Chlorophyceae (7), Dinophyceae (3) and Bacillariophyceae (83) were reported in the present study. Species diversity and density was recorded highest at Ranpar estuary and from Bacillariophyceae it was greater than other divisions. Diversity index is very high due to number of contributing species. He result concluded that the selected estuaries are more fertile with rich phytoplankton productivity.

Composition and Diversity of Algal Flora in Jahanara Imam-Pritilota Hall Sorobar (JP) Lake of Jahangirnagar University Campus, Savar, Dhaka, Bangladesh

The study aimed to evaluate the composition and diversity of algae in the JP Lake of Jahangirnagar University campus. The research was carried out between the period of December 2021 to November 2022. A total of 72 water samples were used to carry out the investigation. Shannon and Simpson diversity indexes were used to determine the level of diversity. 234 phytoplankton species under 98 genera were found belonging to 8 classes (Cyanophyceae, Chlorophyceae, Bacillariophyceae, Synurophyceae, Euglenophyceae, Cryptophyceae, Dinophyceae, and Xanthophyceae). According to the generic percentage composition, Chlorophyceae comprised 46%, followed by Bacillariophyceae (20%) and Cyanophyceae (18%). At the species level, Euglenophyceae were found to dominate (34%) the studied sites that were followed by Chlorophyceae (31%) and Cyanophyceae (18%). The total density of phytoplankton was 387.34×105 ind/l. The highest phytoplankton density was found in April, and the lowest one was in November. Cell dispersion was below average in May for Cyanophyceae, Bacillariophyceae, Cryptophyceae, and Synurophyceae. Oscillatoria, Monoraphidium, Actinastrum, Cosmarium, Trachelomonas, and Euglena dominated the surveyed region. The Shannon Diversity Index showed a value of 1.51, while Simpson's Diversity Index showed a value of 0.28. The overall variation (80.73%) among the classes was represented by PCA cells. According to the Shannon and Simpson Diversity Indexes, the diversity was low.

Taxonomic study and local environmental conditions of occurrence of Chlorophyceae (Chlorophyta) from subtropical lotic environments, Paraná, Brazil / Estudo taxonômico e condições ambientais locais da ocorrência de Chlorophyceae (Chlorophyta) de ambientes lóticos subtropicais, Paraná, Brasil

Abstract Lotic environments are subjected to the impacts of human activities in an intense way in urban regions and one of the ways to assist in the environmental diagnosis is through the knowledge of the composition of bioindicator organisms, including microalgae. The objective of this work was to qualitatively characterize the Chlorophyceae Class Wille, providing descriptions and meristic data of the specimens as well as the environmental conditions in which the taxa were recorded. Water and phytoplankton samplings were carried out quarterly in 2020, in nine supply rivers, distributed in three river basins in the western region of Paraná (Paraná III basin, Piquiri basin and Baixo Iguaçu basin). The studied rivers were classified as oligotrophic or mesotrophic and the taxa were mostly rare. Thirty-six taxa belonging to the Chlorophyceae class were recorded, distributed in five families: Hydrodictyaceae Dumortier, Neochloridaceae Ettl & Komárek, Radiococcaceae Fott ex P.C.Silva, Scenedesmaceae Oltmanns, Selenastraceae Blackman & Tansley. These taxa have mainly cenobial representatives, with about 70% of the individuals in this thallus configuration, followed by 22% colonies and 8% unicellular thallus. Among the identified species, five occurred only in mesotrophic sites, warning for environments with tendencies to elevate their trophic, since they are genera previously associated with these conditions. Ten new citations were recorded for the State of Paraná, namely: Pseudopediastrum boryanum var. longicorne (Reinsch) P.M.Tsarenko, Radiococcus skujae I.Kostikov, T.Darienko, A.Lukesová & L.Hoffmann, Desmodesmus perforatus (Lemmermann) E.Hegewald, Desmodesmus subspicatus (Chodat) E.Hegewald & A.W.F.Schmidt, Scenedesmus indicus Philipose ex Hegewald, Engelberg & Paschma, Ankistrodesmus bernardii Komárek, Monoraphidium capricornutum (Printz) Nygaard, Monoraphidium caribeum Hindák, Raphidocelis danubiana var. elegans (Playfair) Taşkin & Alp, Selenastrum rinoi Komárek & Comas. Taxonomic studies, such as this one, are an important tool for understanding the flora, and in addition to contributing to the registration of species in aquatic ecosystems, they serve as a basis for ecological studies and other approaches used to preserve biodiversity in these places.

Resumo Ambientes lóticos são ecossistemas muito vulneráveis aos impactos das atividades humanas, especialmente em regiões urbanas, e uma das formas para auxiliar no diagnóstico ambiental é utilizando o conhecimento da composição dos organismos bioindicadores, dentre eles as microalgas. O objetivo foi caracterizar qualitativamente as microalgas enquadradas na Classe Chlorophyceae Wille, fornecendo descrições e dados merísticos dos espécimes bem como as condições ambientais em que os táxons foram registrados. Foram realizadas amostragens de água e de fitoplâncton trimestralmente no ano de 2020, em nove rios de abastecimento, distribuídos em três bacias hidrográficas da região oeste do Paraná (bacia do Paraná III, bacia do Piquiri e bacia do Baixo Iguaçu). Os rios estudados foram enquadrados como oligotróficos ou mesotróficos e os táxons apresentaram em sua maioria ocorrência rara. Foram registrados 36 táxons pertencentes a classe Chlorophyceae distribuídos em cinco famílias: Hydrodictyaceae Dumortier, Neochloridaceae Ettl & Komárek, Radiococcaceae Fott ex P.C.Silva, Scenedesmaceae Oltmanns, Selenastraceae Blackman & Tansley. Esses táxons possuem representantes principalmente cenobiais, apresentando cerca de 70% dos indivíduos nessa configuração de talo, seguido por 22% de colônias e 8% de talos unicelulares. Entre as espécies identificadas, cinco ocorreram somente em locais mesotróficos, advertindo para ambientes com tendências a elevar sua trofia, visto que são gêneros já associados anteriormente a essas condições. Foram registradas 10 novas citações para o Estado do Paraná, sendo estas: Pseudopediastrum boryanum var. longicorne (Reinsch) P.M.Tsarenko, Radiococcus skujae I.Kostikov, T.Darienko, A.Lukesová & L.Hoffmann, Desmodesmus perforatus (Lemmermann) E.Hegewald, Desmodesmus subspicatus (Chodat) E.Hegewald & A.W.F.Schmidt, Scenedesmus indicus Philipose ex Hegewald, Engelberg & Paschma, Ankistrodesmus bernardii Komárek, Monoraphidium capricornutum (Printz) Nygaard, Monoraphidium caribeum Hindák, Raphidocelis danubiana var. elegans (Playfair) Taşkin & Alp, Selenastrum rinoi Komárek & Comas. Trabalhos taxonômicos, como este, são uma importante ferramenta para o conhecimento da flora, e além de contribuir no registro das espécies nos ecossitemas aquáticos, servem como base para estudos ecológicos e demais abordagens utilizadas na preservação da biodiversidade nesses locais.

Especies invasoras de Ceratium Schrank, 1973 (Dinophyceae: Ceratiaceae) en cuerpos de agua continentales de Perú

La presente comunicación proporciona información de la presencia en Perú de dos especies invasoras del género Ceratium: C. hirundinella (O.F. Müller) Dujardin y C. furcoides (Levander) Langhans. Se brinda información sobre la distribución de ambas especies en cuerpos de agua peruanos, así como datos de sus abundancias.

This works provides information on the presence in Peru of two invasive species of the genus Ceratium: C. hirundinella (O.F. Müller) Dujardin and C. furcoides (Levander) Langhans. Information is provided on the distribution of both species in Peruvian water bodies, as well as data on their abundance.

SEASONAL VARIATION IN WATER QUALITY AND PHYTOPLANKTON PRODUCTION IN JOHILA RESERVOIR, LALPUR, AMARKANTAK (M.P.)

Present study has been undertaken in order to assemble knowledge regarding physicochemical parameters analysis from June 2021 – May 2022 in relation to the abundance, composition and seasonal variation in the phytoplankton of Johila reservoir Lalpur Podki, Amarkantak (M.P.). It is interiorly located at Latitude 22046'20, Longitude, 81044'39'' in Lalpur and no study regarding hydrobiology in general and phytoplankton abundance in particular has yet not been conducted. Johila reservoir has its origin from Jwaleshwar temple kund of Amarkantak, hill located in Makel velly. It starts flowing opposite site to the Narmada River after 15 Kilometre and finally joins the river Sone at Dasrathghat of Umaria District of Madhya Pradesh. Total area of Johila reservoir is 86 hectare (216 acers). Since no study yet has been done on phytoplankton production in relation to its physico-chemical characteristic hence present study has been undertaken. Phytoplankton population were dominated by Chlorophyceae, Myxophyceae and Bacillariophyceae in decreasing order. Chlorophyceae members revealed dominance over Myxophyceae and Bacillariophyceae.

Distribution and abundance of dinoflagellates from the coastal waters of Karachi, Pakistan, northern part of the Arabian Sea / Distribuição e abundância de dinoflagelados nas águas costeiras de Karachi, Paquistão, parte norte do Mar da Arábia

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-¹ 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-¹). 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.

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.

Distribution and abundance of dinoflagellates from the coastal waters of Karachi, Pakistan, northern part of the Arabian Sea

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 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.

Distribution and abundance of dinoflagellates from the coastal waters of Karachi, Pakistan, northern part of the Arabian Sea / Distribuição e abundância de dinoflagelados nas águas costeiras de Karachi, Paquistão, parte norte do Mar da Arábia

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.

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.

Toxinas Algales en el Mar Argentino: nuevos hallazgos, nuevos desafíos / Algal Toxins in the Argentine Sea: new findings, new challenges

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 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.

Características morfológicas de las cianobacterias y fitoplancton dominante en embalses de Antioquia: un enfoque basado en el biovolumen / Morphological characteristics of cyanobacteria and dominant phytoplankton in reservoirs in Antioquia: a focus based in biovolume

RESUMEN El desarrollo masivo de cianobacterias y la contaminación por cianotoxinas constituyen una problemática ambiental de especial interés en los sistemas acuáticos, debido a los diversos impactos negativos que los florecimientos (blooms) de cianobacterias pueden ocasionar. Dada la importancia recreacional y de abastecimiento de los embalses Abreo - Malpaso, Peñol - Guatapé y Playas, ubicados en el oriente de Antioquia - Colombia, en este estudio, se estimó la densidad de cianobacterias planctónicas y otros organismos del fitoplancton, así como el biovolumen geométrico, la relación superficie volumen (S/V) y la dimensión lineal máxima (DLM), a través de cuatro muestreos, en tres estaciones, para cada uno de los embalses. Se identificaron, dentro del phylum Cyanobacteria, con potencial de producción de cianotoxinas, el complejo Microcystis, los géneros Woronichinia, Aphanocapsa y Oscillatoria y la especie Radiocystis fernandoi. Al aplicar la prueba no parámetrica Kruskal - Wallis, no se encontraron diferencias significativas entre los embalses estudiados (p>0,05); sin embargo, el embalse El Peñol - Guatapé presentó la mayor biomasa algal y densidad de cianobacterias, por lo que, según los niveles de riesgo planteados para los embalses estudiados y de acuerdo con las características morfológicas de estos organismos, este embalse presenta un nivel de riesgo Medio Alto con relación a la presencia y morfología de las cianobacterias, mientras que los embalses Abreo - Malpaso y Playas están asociados a un riesgo Medio Bajo. Se sugiere establecer medidas de control y de prevención, con el fin de evitar un desarrollo masivo de cianobacterias, una potencial presencia de cianotoxinas y afectaciones graves a seres humanos y animales.

ABSTRACT Cyanotoxin contamination is of special interest in water bodies, especially those for human use, due to the various negative effects that blooms of potentially toxic cyanobacteria can cause on human health. Given the recreational and supply importance of the Abreo - Malpaso, Peñol - Guatapé and Playas reservoirs in the Department of Antioquia, Colombia. This study has estimated the biomass of the planktonic cyanobacteria, their geometric biovolume, the surface volume ratio (S / V) and the maximum linear dimension (MLD), during four sampling seasons in three different stations for each of these bodies. Water. We have identified from the Cyanophyta division with the production of cyanotoxins, the Microcystis complex and generates Woronichinia, Aphanocapsa and Oscillatoria, as well as the species Radiocystis fernandoi. When applying the nonparametric Kruskal - Wallis test, no significant differences were found between the studied reservoirs (p> 0.05); however, the Peñol - Guatapé reservoir presented the highest algae biomass and density of cyanobacteria, therefore, according to the levels of risk posed for the reservoirs studied and according to the morphological characteristics of these organisms, this reservoir presents a High Medium risk level in relation to the presence and morphology of the cyanobacteria, while the Abreo-Malpaso and Playas reservoirs are associated with a Medium Low risk. It is suggested to establish control and prevention measures to avoid a massive development of cyanobacteria, a possible presence of cyanotoxins and serious affectations in humans and animals.

Plankton variation in Río Cuarto Lake, Costa Rica (2013-2017)

En los lagos tropicales, los cambios estacionales en la dinámica del plancton son mínimos e irregulares, ya que las condiciones climáticas son bastante estables durante todo el año, en la mayoría de los casos solamente estudios a largo plazo permiten observar patrones en la dinámica del plancton. El lago de Río Cuarto es un lago meromícto tipo maar localizado en las llanuras del norte de Costa Rica, en el pasado se han realizado estudios limnológicos no mayores a un año de muestreo, en este trabajo presentamos datos de la composición del fitoplancton y del zooplancton a lo largo de cuatro años, del 2013 al 2017, con el fin de analizar cambios en la comunidad del plancton en un periodo de tiempo mayor, asociados a variables ambientales. Para el fitoplancton se tomaron muestras subsuperficiales y se fijaron con lugol, y para el zooplancton se hicieron arrastres verticales de 20 m con una red con 64 µm de poro, que se preservaron con formalina y luego se pasaron a alcohol de 95 %. El fitoplancton incluyó 54 taxa, la mayoría fue Chlorophyta, seguidos por Cyanobacteria y Bacillariophyta. Las taxa más comunes fueron: Synechococcus spp., Aphanocapsa sp. Coenochloris fotii, Chlorella sp. y Discostella stelligera. La abundancia total del fitoplancton disminuyó de 2013 a 2017, principalmente debido a una disminución en las Cyanobacteria. El zooplancton estuvo compuesto por 14 taxa: 5 cladóceros, 4 copépodos, 1 díptero y 4 rotíferos. Los más abundantes fueron: Keratella americana, Brachionus falcatus, Eubosmina tubicen y Arctodiaptomus dorsalis. Se observó un cambio en la diversidad y abundancia del zooplancton, al principio (2013-2014) K. americana y E. tubicen se alternaron en dominancia, y luego (2015-2016) A. dorsalis, Diaphanosoma sp. y Ceriodaphnia sp. fueron dominantes, con un regreso de K. americana en el 2017. Los cambios observados en el periodo de estudio parecen estar relacionados con cambios en la condición del lago, pues la termoclina se hundió y el lago se volvió más trasparente durante el estudio. La abundancia, de rotíferos y del cladócero Eubosmina tubicen, disminuyó asociada a una disminución de Cyanobacterias. Esos cambios no siguieron un ciclo anual, más bien parecen cambios que ocurren a largo plazo, tal y como se ha propuesto en la literatura sobre lagos tropicales.

In tropical lakes, seasonal changes in plankton dynamics are minimal and irregular, since climatic conditions are fairly stable throughout the year, in most cases only long-term studies allow observing patterns in the dynamics of the plankton. Lake Río Cuarto is a maar-type meromic lake located in the plains of Northern Costa Rica, in the past there have been no limnological studies more than a year of sampling, in this work we present data on the composition of phytoplankton and zooplankton over four years, from 2013 to 2017, with the aim of analyzing changes in the plankton community in a longer period, associated with environmental variables. Phytoplankton was studied from subsurface samples, preserved in Lugol's solution and zooplankton from 20 m vertical hawls of a 64 µm mesh net, and preserved with formaline and later transferred to 95 % ethanol. Phytoplankton composition included 54 taxa, most of them were Chlorophyta, followed by Cyanobacteria and Bacillariophyta. The most abundant were: Synechococcus spp., Aphanocapsa sp. Coenochloris fotii, Chlorella sp. and Discostella stelligera. Total phytoplankton decreased from 2013 to 2017, mainly due to a decrease in Cyanobacteria. Zooplankton comprised 14 taxa, 5 cladocerans, 4 copepods, 1 diptera and 4 rotifers. The most abundant were: Keratella americana, Brachionus falcatus, Eubosmina tubicen and Arctodiaptomus dorsalis. There was a substitution of dominant species through time, at first (2013-2014) K. americana and E. tubicen alternated in dominance, and later (2015-2016), A. dorsalis, Diaphanosoma sp. and Ceridaphnia sp. became dominant, with a return of K. americana by 2017. The changes that occurred during the time of the study seem to be related to changes in the conditions of the lake, since its thermocline deepened with time and became more transparent. The abundance, of rotifers and Eubosmina tubicen, decreased associated to a decrease of Cyanobacteria. Those changes were not cyclical on an annual basis, but seemed to occur more on a long-term basis, as has been recognized earlier in the literature about tropical lakes.

ASPECTOS MORFOLÓGICOS Y PRIMER REGISTRO DEL DINOFLAGELADO Pronoctiluca spinifera EN EL CARIBE COLOMBIANO

Se registró por primera vez la presencia del dinoflagelado atecado Pronoctiluca spinifera (Lohman) (Schiller, 1933) en el Parque Nacional Natural Corales de Profundidad-PNNCPR del Caribe colombiano. Fueron hallados a uno y 40 m de profundidad, tres ejemplares con tamaño promedio de 54,84 µm de largo y 10,29 (m de ancho; de contorno fusiforme con dos proyecciones, una en forma de tentáculo (13,56 µm) y otra puntiaguda. Los sitios de muestreo se caracterizaron por temperaturas entre 27,7 y 30,3 °C; salinidad entre 35,6 y 36,4 y clorofila a entre 0,0801 y 0,1741 mg/m3; valores típicos de ambientes oceánicos. Con el presente trabajo se amplía la distribución de P. spinifera hallándose por primera vez en el mar Caribe Colombiano en el PNNCPR.

The presence of the unarmored dinoflagellate Pronoctiluca spinifera (Lohman) Schiller (1933) was recorded for the first time in the Parque Nacional Natural Corales de Profundidad-PNNCPR, in the Colombian Caribbean. Three specimens with an average size of 54.84 µm long and 10.29 wide were found at one and 40 m depth; of the fusiform outline with two projections, one in the form of the tentacle (13.56 pm) and another pointed. The sampling sites were characterized by temperatures between 27.7 and 30.3 °C; salinity between 35.6 and 36.4 and Chlorophyll a between 0.0801 and 0.1741 mg / m3; typical values of oceanic environments. With this paper, the distribution of P. spinifera is extended, being found for the first time in the Colombian Caribbean Sea in the PNNCPR.

Dinoflagelados potencialmente tóxicos asociados a pastos marinos en Isla de Barú, Caribe Colombiano, durante El Niño 2015 / Potentially toxic dinoflagellates associated to seagrass on isla de barú, colombian caribbean, during el niño 2015

ABSTRACT In the last decades, harmful algal blooms (HAB) and toxic events such as ciguatera seem to have increased in frequency and intensity, negatively impacting human health, economy, and marine ecosystems. In Colombia, these events have caused a series of consequences ranging from the death of fish and birds to toxic effects on humans. Although some toxin-producing dinoflagellate species are common in the Caribbean, their dynamics are poorly understood, making the adoption of any regulations difficult. To determine the composition and abundance of dinoflagellates associated with seagrasses we collected 18 samples on Isla de Barú, during 2015. We found ten diatom genera and three dinoflagellate genera, Prorocentrum, Ostreopsis, and Gambierdiscus, that include toxigenic species related to ciguatera and diarrheic shellfish poisoning. Prorocentrum lima was the most abundant dinoflagellate, with average cell densities of 52±48 cells/g substrate wet weight. The temperature hypothesis gains strength as one of the main modulators of dinoflagellate abundance observed in the Caribbean, especially regarding Prorocentrum species and some diatoms such as Mastogloia corsicana and Actinocyclus normanii. This assumption is supported by the Since high positive correlation between El Niño Southern Oscillation and the sea surface temperature in the Caribbean during 2015.

RESUMEN En las últimas décadas, las floraciones de algas nocivas (FAN) y los eventos tóxicos, como la ciguatera, parecen haber aumentado en frecuencia e intensidad, afectando negativamente la salud humana, la economía y los ecosistemas marinos. En Colombia, estos eventos han causado una serie de consecuencias que van desde la muerte de peces y aves hasta efectos tóxicos en los seres humanos. Aunque algunas especies de dinoflagelados que producen toxinas son comunes en el Caribe, su dinámica es poco conocida, lo que dificulta la adopción de cualquier regulación. Para determinar la composición y abundancia de dinoflagelados asociados con los pastos marinos, recolectamos 18 muestras en Isla de Barú durante 2015. Encontramos diez géneros de diatomeas y tres géneros de dinoflagelados, Prorocentrum, Ostreopsis y Gambierdiscus, que incluyen especies toxigénicas relacionadas con la ciguatera y la intoxicación diarreica por mariscos. Prorocentrum lima fue el dinoflagelado más abundante, con densidades celulares promedio de 52 ± 48 células / g de peso húmedo de sustrato. La hipótesis de la temperatura gana fuerza como uno de los principales moduladores de la abundancia de dinoflagelados observados en el Caribe, especialmente con respecto a las especies de Prorocentrum y algunas diatomeas como Mastogloia corsicana y Actinocyclus normanii. Este supuesto está respaldado por la alta correlación positiva entre la Oscilación Sur de El Niño y la temperatura de la superficie del mar en el Caribe durante 2015.

Sodium and nitrate favor the steady state of cyanobacteriain a semiarid ecosystem

This study characterized steady state events (SS) in a semiarid reservoir (Brazil) dominated by cyanobacteria for 130 weeks, and evaluated the influence of different abiotic variables on their occurrence. It was hypothesized that, in semiarid reservoirs, steady state events are independent from seasonality and influenced by high nutrient concentrations, and steady state periods show low variation of species. Our data revealed the occurrence of SS events in both the dry and wet seasons. Higher concentrations of nitrate and sodium together with higher values of color favored the development of SS. Species composing the SS dominated by Microcystis aeruginosa (Kützing) Kützingwas correlated with higher sulfate concentrations, while higher values of turbidity and sodium concentrations favored the SS of Cylindrospermopsis raciborskii (Woloszynska) Seenaya and Suba Rajuand Planktothrix agardhii (Gomont) Anagnostidis and Komárek. The results supported the hypothesis and showed the importance of variables rarely evaluated in works of this nature, such as sodium and sulfate in SS establishment of cyanobacteria.

Zeaxanthin from Porphyridium purpureum induces apoptosis in human melanoma cells expressing the oncogenic BRAF V600E mutation and sensitizes them to the BRAF inhibitor vemurafenib

Abstract Zeaxanthin, an abundant carotenoid present in fruits, vegetables and algae was reported to exert antiproliferative activity and induce apoptosis in human uveal melanoma cells. It also inhibited uveal melanoma tumor growth and cell migration in nude mice xenograft models. Here we report that zeaxanthin purified from the rhodophyte Porphyridium purpureum (Bory) K.M.Drew & R.Ross, Porphyridiaceae, promotes apoptosis in the A2058 human melanoma cell line expressing the oncogenic BRAF V600E mutation. Zeaxanthin 40 µM (IC50) induced chromatin condensation, nuclear blebbing, hypodiploidy, accumulation of cells in sub-G1 phase, DNA internucleosomal fragmentation and activation of caspase-3. Western blot analysis revealed that zeaxanthin induced up-regulation of the pro-apoptotic factors Bim and Bid and inhibition of NF-κB transactivation. Additionally, zeaxanthin sensitized A2058 melanoma cells in vitro to the cytotoxic activity of vemurafenib, a BRAF inhibitor widely used for the clinical management of melanoma, suggesting its potential interest as dietary adjuvant increasing melanoma cells sensitivity to chemotherapy.

Comparative reservoir limnology in Juramento (Salta) and Salí-Dulce (Tucumán) Basins in Argentina / Limnología comparada de los embalses de las cuencas de Juramento (Salta) y Salí-Dulce (Tucumán) en Argentina

Abstract The reservoirs of the upper Juramento basin (Cabra Corral and El Tunal) and the Salí-Dulce basin (El Cadillal, Río Hondo, and Escaba) show certain peculiarities due to their geographical location, basin morphology and limnological features. Such peculiarities were compared during significant algal bloom periods between 2002 and 2008, by analyzing the main physicochemical parameters and ecological attributes of the phytoplankton assemblages using standard methods. Tucumán reservoirs were different in most variables showing higher values of conductivity, nutrients and algal biomass. Regarding the hydrological cycle, El Cadillal exhibited the lowest biomass average (2.74 mg Chl.m-3) during maximum water flows, whereas the Cabra Corral lacustrine zone exhibited the highest biomass average (63.36 mg Chl.m-3) during minimum water flows. For the same period, the Cabra Corral lacustrine zone exhibited lower phytoplankton diversity and richness (1.37 and 9, respectively), in accordance with dinophyte blooms of Ceratium sp. In all reservoirs, the following biological variables showed a significant contrast in the hydrological cycle: highest phytoplankton biomass during minimum water flows (35.68 mg Chl-a m-3) vs. waterfloods (13.68 mg Chl-a m-3) (T = 3.42, P = 0.001). During minimum water flows, richness (14.30 sp.) and equitability (0.51) were lower vs. waterfloods (20.23, 0.59, respectively) (T = 2.36; P = 0.0196), as a result of the allochthonous nutrients provided by the main tributaries. Management of the reservoirs' hydrometric levels during dry season determines the deterioration of the water quality with increased algal blooms. In order to ensure the systems' sustainability, eutrophication must be controlled with programs to reduce diffuse nutrient loads and to treat residential and agroindustrial effluents, particularly in Sali-Dulce basin. Rev. Biol. Trop. 66(1): 415-427. Epub 2018 March 01.

Resumen Los embalses de la Alta Cuenca del Juramento (Cabra Corral y El Tunal) y del Salí-Dulce (El Cadillal, Río Hondo y Escaba) por su ubicación geográfica, morfología y características limnológicas muestran ciertas peculiaridades que son comparadas en el período relevante de proliferaciones algales acaecidas entre 2002 y 2008, mediante análisis de los principales parámetros fisicoquímicos y atributos ecológicos de los ensambles del fitoplancton por empleo de técnicas estandarizadas. Los embalses de Tucumán se diferenciaron en la mayoría de las variables con valores más elevados de conductividad, nutrientes y biomasa de algas. En función del ciclo hidrológico, El Cadillal en aguas altas presentó el promedio más bajo de biomasa (2.74 mg Cl.m-3) y en contraste Cabra Corral el más elevado (63.36 mgCl.m-3) durante los caudales mínimos de agua. En éste último, en el mismo período, también la diversidad y riqueza de especies del fitoplancton fueron menores (1.37 y 9 respectivamente), en concordancia con las proliferaciones de dinófitos (Ceratium sp.). Las siguientes variables biológicas en el conjunto de embalses presentaron un contraste significativo en el ciclo hidrológico: biomasa del fitoplancton más elevada en estiaje (35.68 mg Cl a. m-3) versus crecidas (13.68 mg Cl a. m-3) (T = 3.42; P = 0.001). En estiaje, la riqueza (14.30 sp) y equitatividad (0.51) fueron menores versus crecidas (20.23, 0.59, respectivamente) (T = 2.36; P = 0.0196), debido al aporte alóctono de nutrientes por los tributarios principales. El manejo de los niveles hidrométricos de los embalses durante el estiaje determina el deterioro de la calidad de sus aguas con incremento de proliferaciones algales. Para asegurar la sustentabilidad de los sistemas, es indispensable el control de la eutrofización mediante programas de reducción de cargas difusas de nutrientes y tratamiento de efluentes domiciliarios y agroindustriales, particularmente en la cuenca del Sali-Dulce.

Phytoplankton functional groups in a tropical reservoir in the Brazilian semiarid region / Grupos funcionales de fitoplancton en una represa tropical de una región semiárida de Brazil

Abstract: Phytoplankton functional groups structure and species abundance vary according to environmental conditions. The present study investigated the natural and anthropogenic stressors that affect phytoplankton functional group biomass in a Brazilian semiarid region reservoir (Argemiro de Figueiredo reservoir). Sampling occurred between August 2007 and July 2009 on a bi-monthly basis for the first year, and in a monthly basis for the last two years. There were three collection points (PC: river confluence; PNC: near the cages; PD: dam site). The water environment analysis of abiotic variables included: temperature, transparency, coefficient of vertical light attenuation, dissolved oxygen, pH, electrical conductivity, alkalinity, dissolved inorganic nitrogen, and reactive soluble phosphorus. Phytoplankton samples were collected into a Van Dorn bottle, and were then preserved in acetic lugol and were quantified using an inverted microscope to determine phytoplankton density and biomass; the identified species were assembled in functional groups. The data were explored by canonical correspondence analysis. Individual analyses were made to test the temporal and spatial variability of the data and the factors that interfered most with the biotic and abiotic variables. Functional groups S1, SN, and K, consisting of filamentous Planktothrix agardhii (Gomont) Anagnostidis & Komárek, Cylindrospermopsis raciborskii (Woloszynska) Seenaya & Subba Raju, and the coccoid Aphanocapsa incerta (Lemmermann) Cronberg & Komárek, respectively, dominated the dry months when the water was warm, turbid, and alkaline. The overflow reservoir served as a natural disturbance reducing the phytoplankton biomass to less than 50 % and the dominance of cyanobacteria, promoting the domain of functional groups F, M, MP, Lo, and X2. The nutrient inputs from intensive fish farming, associated with a low local depth (Zmax = 7.7 m) close to the cages (PNC), resulted in a significant human disturbance that increased the prevalence of functional groups S1, SN, and K, which are composed primarily of cyanobacteria. We concluded that, in reservoirs, overflow events are natural disturbances that have the ability to reduce phytoplankton biomass and alter the structure of local communities, and that intensive fish farming is an anthropogenic disturbance that increases the availability of nutrients and stimulates an increase in biomass of the functional groups that include cyanobacteria. Furthermore, the functional groups of phytoplankton were reliable control of environmental conditions in the reservoirs of tropical semiarid regions. Rev. Biol. Trop. 65 (3): 1129-1141. Epub 2017 September 01.

Resumen: La estructura de grupos funcionales del fitoplancton y la abundancia de especies varían de acuerdo con las condiciones ambientales. Este estudio investigó los estresores naturales y antropogénicos que afectan la biomasa de grupos funcionales de fitoplancton en una represa (la represa de Argemiro de Figueiredo) en una región semiárida de Brasil. La recolecta de datos fue entre agosto 2007 y julio 2009 de forma bimensual durante el primer año, y de forma mensual durante los últimos dos años. Estos se recolectaron en tres sitios (PC: confluencia del río; PNC: cerca de las jaulas; PD: sitio de la represa). El análisis de las variables abióticas del agua incluyó: temperatura, transparencia, coeficiente de atenuación vertical de la luz, oxígeno disuelto, pH, conductividad eléctrica, alcalinidad, nitrógeno inorgánico disuelto y fósforo reactivo soluble. Las muestras de fitoplancton fueron recolectadas en una botella Van Dorn, y fueron preservadas en lugol acético y cuantificadas utilizando un microscopio invertido para determinar la densidad y la biomasa del fitoplancton, las especies identificadas fueron agrupadas en grupos funcionales. Los datos fueron explorados mediante un análisis de correspondencia canónica. Los análisis individuales fueron hechos para probar la variabilidad espacial y temporal de los datos y los factores que más interfieren con las variables bióticas y abióticas. Los grupos funcionales S1, SN, y K, incluyen las algas filamentosas: Planktothrix agardhii (Gomont) Anagnostidis & Komárek, Cylindrospermopsis raciborskii (Woloszynska) Seenaya & Subba Raju, y algas cocoides: Aphanocapsa incerta (Lemmermann) Cronberg & Komárek, respectivamente dominando los meses cálidos cuando el agua estuvo caliente, turbia y alcalina. El desbordamiento de la reserva funciona como una alteración natural, reduciendo la biomasa del fitoplancton a menos de un 50 % y la dominancia de cianobacterias, promoviendo el dominio de los grupos funcionales F, M, MP, Lo y X2. La llegada de nutrientes debido a la pesca intensiva, asociado con una baja profundidad local (Zmax = 7.7 m), cerca de las jaulas (PNC), resulta en una alteración humana significativa que incrementa la prevalencia de los grupos funcionales S1, SN y K, los cuales están compuestos principalmente por cianobacterias. Concluimos que, en las represas, eventos de desborde son perturbaciones naturales que tienen la habilidad para reducir la biomasa del fitoplancton y alterar la estructura de las comunidades locales, y que la pesca intensa es una alteración antropogénica que incrementa la disponibilidad de nutrientes y estimula el incremento de la biomasa de los grupos funcionales que incluyen las cianobacterias. Además, los grupos funcionales de fitoplancton fueron controles confiables de las condiciones ambientales en las represas de las regiones semiáridas tropicales.

Morfología funcional del fitoplancton en un lago de alta montaña tropical: Lago de Tota (Boyacá-Colombia) / Functional morphology of phytoplankton in a tropical high mountain lake: Tota Lake (BoyacáColombia)

ResumenLa morfología funcional corresponde a las respuestas de adaptación a los cambios en el medio ambiente. En fitoplancton, rasgos como el desarrollo de mucílago, vesículas de aceite, filamentos y variación en la relación superficie/ volumen, permiten enfrentar la sedimentación, optimizar la captación lumínica y de nutrientes. El objetivo del presente estudio fue evaluar la relación entre los rasgos y la variación de las condiciones físicas y químicas en el lago de Tota (Boyacá, Colombia). Para esto, se realizaron diez muestreos mensuales entre octubre 2013 y julio 2014. Se midieron el pH, conductividad eléctrica, temperatura, oxígeno disuelto, saturación de oxígeno, alcalinidad y dureza total del agua. Además se recolectaron muestras para la cuantificación en laboratorio de Nitrógeno Total Kjeldahl y Fósforo Total. Las algas se obtuvieron en diferentes profundidades según la transparencia Secchi. Se caracterizó la composición taxonómica y se estimó la abundancia por el método de sedimentación en cámaras. Se midieron los rasgos morfológicos de cada taxa según la correspondencia a modelos geométricos, se clasificaron en grupos funcionales basados en morfología (GFBM) y se calculó su biomasa expresada como biovolumen. Las variables fueron evaluadas mediante Análisis de Componentes Principales, que incluyó el efecto espacio-temporal y fue interpretado según la variación en el nivel del agua. Mediante Análisis de Correspondencia Canónica se estableció la relación entre el biovolumen del fitoplancton acumulado en categorías de forma y las variables ambientales. La ordenación mostró que las condiciones limnológicas son influenciadas por cambios estacionales, principalmente representadas por el porcentaje de saturación de oxígeno, la transparencia Secchi, el NTK, la dureza y la alcalinidad. Se encontraron cuatro GFBM: IV, V, VI y VII, siendo los GFBM IV y VII, los más representativos. El ACC fue significativo (Test de Monte-Carlo, p<0.05). En conclusión, la respuesta morfológica y funcional del fitoplancton del lago de Tota esta condicionada principalmente por la variabilidad a corto plazo, en la transparencia, el fósforo, el nitrógeno, la dureza y la conductividad eléctrica, que son afectados por los cambios estacionales en el nivel del lago.

AbstractFunctional morphology corresponds to adaptive responses to changes in the environment. In phytoplankton, traits such as the development of mucilage, oil vesicles, filaments and variation in the surface/volume ratio, allow algae to deal with sedimentation, optimizing light and nutrient uptake. The aim of this research was to evaluate the relationship between traits and variation in physical and chemical conditions in Tota Lake (Boyacá, Colombia). For this, ten samplings were undertaken in a monthly basis between October 2013 and July 2014. We measured water pH, conductivity, temperature, dissolved oxygen, oxygen saturation, alkalinity and total hardness; we also quantified Total Kjeldahl nitrogen and Total phosphorus. Algae were collected at different depths according to Secchi transparency. Taxonomic composition and abundance were estimated by the chamber sedimentation method. Morphological traits were measured for each taxa according to geometric models, allowing traits classification into morphologically based functional groups (MBFG) and having algae biomass expressed as biovolume. The variables were evaluated through Principal Components Analysis, which included time-space effect and it was interpreted according to variation in water level. Through Canonical Correspondence Analysis we established the relationship between phytoplankton biovolume accumulated in form categories and environmental variables. The ordination showed that limnological conditions are influenced by seasonal changes, which are mainly represented by oxygen saturation percentage, Secchi transparency, TKN, hardness and alkalinity. Four MBFG were found: IV, V, VI and VII, being MBFG IV and VII the most representatives. ACC was significant (Monte-Carlo Test, p<0.05). In conclusion, the morphological and functional response of phytoplankton in Tota Lake is driven by short-term variability in transparency, phosphorus, nitrogen, hardness, and electrical conductivity, which are all affected by seasonal changes in the lake level.

One year weekly dynamics of limnological conditions and phytoplankton in Lake Bonilla, Costa Rica

Abstract:The detailed response of tropical lake phytoplankton to weather variations has been little studied, but it seems that composition varies in response to rain and wind variability over the course of the year. In order to gather more evidence on this variation, the weekly variability of phytoplankton composition was studied in Lake Bonilla, a low land (380 masl) 30 m deep tropical lake, from April 2010 to May 2011. Temperature variation at several depths was recorded automatically, and measurements of dissolved oxygen, water transparency, and nutrients were performed several times during the study period. The lake showed a warm monomictic pattern, with deep mixing occurring during the hemispherical winter, especially after a heavy rain period in December 2010. Phytoplankton was dominated by a few species: a colonial Cyanobacteria (Aphanocapsa sp., functional group F) and two colonial Chlorococcaceae (Botryococcus braunii and Eutetramorus tetrasporus, both in the functional group K). Their relative dominance shifted throughout the year, following changes in water column conditions in response to weather variations. Although changes in main functional groups indicate a shift in resource availability rather than energy, it was clear that attention should also be given to particular species adaptations beyond those used for establishing functional groups. Rev. Biol. Trop. 64 (4): 1771-1781. Epub 2016 December 01.

Resumen:La respuesta detallada del fitoplancton de lagos tropicales a las variaciones climáticas ha sido poco estudiada, sin embargo al parecer la composición de especies varía en respuesta a la variabilidad de la precipitación y de los vientos a lo largo del año. Con el fin de recabar más evidencia de esta variación, se estudió semanalmente la composición del fitoplancton en el lago Bonilla, un lago tropical de zonas bajas (380 msnm), de 30 m de profundidad, entre abril 2010 y mayo 2011. Se registró la temperatura del agua a varias profundidades, y se realizaron mediciones de oxígeno disuelto en la columna de agua, trasparencia del agua y concentración de nutrientes varias veces a lo largo del año de estudio. El lago es monomíctico cálido, con una mezcla profunda durante el invierno hemisférico, especialmente luego de un periodo de fuertes precipitaciones en diciembre 2010. El fitoplancton estuvo dominado por pocas especies: una Cyanobacteria colonial (Aphanocapsa sp., grupo funcional F), y dos Chlorococcaceae coloniales (Botryococcus braunii y Eutetramorus tetrasporus, ambas del grupo funcional K). Sus abundancias relativas cambiaron a lo largo del año, siguiendo los cambios en las condiciones de la columna de agua que es influenciada por variaciones en el tiempo atmosférico. Aunque los cambios en los grupos funcionales indican que hubo un cambio en la disponibilidad de recursos en vez de energía radiante, fue evidente que se debe prestar también atención a las adaptaciones particulares de las especies más allá de las que se usan normalmente para establecer los grupos funcionales.