Using in situ flow cytometry images of ciliates and dinoflagellates for aquatic system monitoring

Abstract

Short-period variability in plankton communities is poorly documented, especially for variations occurring in specific groups in the assemblage because traditional analysis is laborious and time-consuming. Moreover, it does not allow the high sampling frequency required for decision making. To overcome this limitation, we tested the submersible CytoSub flow cytometer. This device was anchored at a distance of approximately 10 metres from the low tide line at a depth of 1.5 metres for 12 hours to monitor the plankton at a site in the biological reserve of Barra da Tijuca beach, Rio de Janeiro. Data analysis was performed with two-dimensional scatter plots, individual pulse shapes and micro images acquisition. High-frequency monitoring results of two interesting groups are shown. The abundance and carbon biomass of ciliates were relatively stable, whereas those from dinoflagellates were highly variable along the day. The linear regression of biovolume measures between classical microscopy and in situ flow cytometry demonstrate high degree of adjustment. Despite the success of the trial and the promising results obtained, the large volume of images generated by the method also creates a need to develop pattern recognition models for automatic classification of in situ cytometric images.Keywords: aquatic systems, microbial ecology, in situ flow cytometry, method. Usando imagem de citometria de fluxo in situ de ciliados e dinoflagelados para o monitoramento de sistemas aquáticos ResumoA variabilidade de curto período em comunidades do plâncton é pouco documentada, especialmente as variações que ocorrem em grupos específicos das assembleias por causa das análises tradicionais serem muito trabalhosas e demoradas. Além disso, não permitem que a alta frequência amostral necessária para a tomada de decisão. Para superar esta limitação, nós testamos o CytoSub, um citômetro de fluxo submersível. Este aparelho foi ancorado a aproximadamente 10 metros de distância da linha de maré baixa a uma profundidade de 1,5 metros por 12 horas para monitorar o plâncton em um sítio da reserva biológica da praia da Barra da Tijuca, Rio de Janeiro. A análise dos dados foi realizada a partir de gráficos de dispersão bidimensionais, pelas assinaturas ópticas individuais escaneadas (pulse shape profile) e aquisição de micro imagens. Resultados do monitoramento de alta frequência de dois grupos interessantes são apresentados.A abundância e a biomassa de carbono de um grupo de ciliados foram relativamente estáveis, ao passo que o grupo de dinoflagelado, foi altamente variável ao longo do dia. O modelo de regressão linear das medidas de biovolume entre a clássica microscopia e a citometria de fluxo in situ apresentou alto grau de ajustamento. Apesar do sucesso deste ensaio e dos resultados promissores obtidos, o grande volume de imagens geradas por este método também gerou a necessidade de se desenvolver modelos de reconhecimento de padrões para a classificação automática de imagens de citometria in situ.Palavras-chave: sistemas aquáticos...

Trait‐based analysis of subpolar North Atlantic phytoplankton and plastidic ciliate communities using automated flow cytometer

“…a) and other aloricate ciliates (e.g., Strombidium spp. ), other studies have suggested that ingestion and retention of cryptophyte chloroplasts is a common feature in many ciliates and certain dinoflagellate taxa (Sjoqvist and Lindholm ; Schoener and McManus ; Pereira et al ).…”

“…1a) and other aloricate ciliates (e.g., Strombidium spp. ), other studies have suggested that ingestion and retention of cryptophyte chloroplasts is a common feature in many ciliates and certain dinoflagellate taxa (Sjoqvist and Lindholm 2011;Schoener and McManus 2012;Pereira et al 2017). In this study, picoeukaryotes were the most abundant phytoplankton group found in Atlantic waters, although they were also present in the other water masses.…”

Microplankton community structure in the subtropical Mlalazi estuary.

“…Because bacteria and phytoplankton are the main food sources for ciliates, it is important that in addition to phytoplankton, ciliates are included in the preliminary study of an aquatic system to understand the community structure, reference conditions and indicator species in relation to water quality. The use of ciliates as bioindicators of water quality has been successful in lotic systems Segovia et al, 2016), marine systems (Guo and Xu, 2019;Pereira et al, 2018;Wu et al, 2016) and estuarine systems (Sivasankar et al, 2018;Kim et al, 2012;Jiang et al, 2011). For example, Tintinnopsis beroidea and Mesodinium pupula are a potential bioindicators of eutrophic conditions or poor water quality, dominating in areas with high nutrient concentration (DIN of 22 µM and DIP of 2.64) associated with large amounts of anthropogenic inputs (Sivasankar et al, 2018;Jiang et al, 2011).…”