Temporal changes of phytoplankton-derived sterols in suspended particulate matter and their implications as biomarkers for phytoplankton abundance in northern Patagonia, Reloncaví Estuarine System (RES), Chile.

The Northern Patagonia coast, characterized by an intricate interaction among terrestrial and marine systems such as Reloncaví Estuarine System (RES), present highly productive marine and aquaculture activities, having a significant socio-economic importance in Chile. Understanding the composition of Organic Matter (OM) in aquatic ecosystems is crucial for elucidating biogeochemical processes, and the use of lipid biomarkers, has proven valuable in identifying OM sources. This study investigates the relationship between phytoplankton biomass indicators, including phytoplankton abundance, chlorophyll-a, and sterol molecules synthesized in high percentages by phytoplankton cells, also known as phytoplankton-derived sterols at the RES. The RES encompasses the Reloncaví Fjord (RF) and the Reloncaví Sound (RS) and exhibits a high influenced by oceanic waters and freshwater discharge from rivers Spatio-temporal sampling was conducted during the austral spring, summer and winter expeditions of 2018 and 2019, at two sites in RS and RF mouth (RFm). Our findings reveal higher sterol concentration at RFm than RS. Notably, high sterol concentrations during austral summer season coinciding with increased phytoplankton abundances. Furthermore, higher concentrations of terrestrial-derived sterols such as ß-sitosterol (C29Δ5) and stigmasterol (C29Δ5,22), at RFm site suggested an input of OM from the inner RF. Phytoplankton-derived sterols such as 24-methylenecholesterol (C28Δ5,24(28)) provide a reliable estimate of total diatom abundance at both sites (RFm and RS), though they showed a lower relationship with taxonomic subgroups and phytoplankton classes in our study area. Hence, phytoplankton-derived sterols can be considered reliable diatom biomarkers, particularly in the RS, where the primary source of OM is predominantly marine, and even with high sterol degradation values at RES. Our study highlights the importance of interpreting changes in sterol abundances as phytoplankton community shifts. To avoid misinterpretation, it is essential to incorporate direct phytoplankton counts in elucidating the complex biosynthetic sources of sterols within the water column.

Microphytoplankton dynamics in Curuperé Estuary at the amazonian mangrove ecosystem / Dinâmica do microfitoplâncton no estuário do Rio Curuperé em um ecossistema de manguezal amazônico

The aim of this study was to evaluate microphytoplankton dynamics and environmental parameters in the estuary of the Curuperé River, located in an Amazonian mangrove ecosystem. Ten sampling sites, where occupied to obtain surface water samples for qualitative and quantitative microphytoplankton analyses, chlorophyll-a, temperature, turbidity, salinity, and pH. Samplings were conducted in four months: in February, May, August and November/2015; the first two months corresponding to rainy season and the last two to dry season. Significant spatiotemporal differences were observed, for diversity, equitability and specific dominance of the microphytoplankton community. In total, 212 taxa were identified and this community was dominated by Bacillariophyta (149 taxa), followed by Myzozoa (29 taxa). The abundance varied from 7,700 ind L-1, (May, sampling site 1) to 343,800 ind L-1, in August (sampling site 4). The diatom Cymatosira belgica was the dominant species, followed by Dimeregramma minor (major peaks of 180,600 ind L-1 and 120,400 ind L-1, respectively) in August at point 4. Phytoplankton biomass indicates an eutrophic estuary as Chlorophyll-a varied from 13.01 to 112.88 mg m-3, probably due to marine shrimp farm effluents. It was possible to identify species strongly indicative of the environment, through analysis of indicator species (IndVal), and their relations with the...(AU)

O objetivo deste estudo foi avaliar a dinâmica microfitoplanctônica e os parâmetros ambientais no estuário do rio Curuperé, localizado em um ecossistema de manguezal na Amazônia. Foram realizados dez pontos de amostragem, utilizando amostras de água superficial para análises qualitativas (rede com malha de 20 µm) e quantitativa do microfitoplâncton, bem como para determinação de clorofila a, temperatura da água superficial, turbidez, salinidade e pH. As amostragens foram realizadas em quatro meses: fevereiro, maio, agosto e novembro, sendo os dois primeiros correspodentes ao período chuvoso e os dois últimos, ao seco. Foram observadas diferenças significativas entre os meses e relacionadas à posição ao longo do eixo estuarino para diversidade, eqüitabilidade e dominância específica na comunidade microfitoplanctônica. Foram identificados 212 com dominância de Bacillariophyta (149 taxa), seguido por Myzozoa (29 taxa). O microfitoplâncton variou de 7.700 ind L-1, (maio, ponto 1) a 343.800 ind L-1, em agosto (ponto 4). A diatomácea Cymatosira belgica foi a espécie dominante, seguida por Dimeregramma minor (maiores picos de 180.600 ind L-1 e 120.400 ind L-1, respectivamente) em agosto no ponto 4. Os valores de clorofila a permaneceram altos ao longo do ano variando de 13,01 a 112,88 mg m-3, provavelmente devido aos efluentes de fazenda de camarões marinhos. Foi possível identificar...(AU)

Microphytoplankton dynamics in Curuperé Estuary at the amazonian mangrove ecosystem / Dinâmica do microfitoplâncton no estuário do Rio Curuperé em um ecossistema de manguezal amazônico

The aim of this study was to evaluate microphytoplankton dynamics and environmental parameters in the estuary of the Curuperé River, located in an Amazonian mangrove ecosystem. Ten sampling sites, where occupied to obtain surface water samples for qualitative and quantitative microphytoplankton analyses, chlorophyll-a, temperature, turbidity, salinity, and pH. Samplings were conducted in four months: in February, May, August and November/2015; the first two months corresponding to rainy season and the last two to dry season. Significant spatiotemporal differences were observed, for diversity, equitability and specific dominance of the microphytoplankton community. In total, 212 taxa were identified and this community was dominated by Bacillariophyta (149 taxa), followed by Myzozoa (29 taxa). The abundance varied from 7,700 ind L-1, (May, sampling site 1) to 343,800 ind L-1, in August (sampling site 4). The diatom Cymatosira belgica was the dominant species, followed by Dimeregramma minor (major peaks of 180,600 ind L-1 and 120,400 ind L-1, respectively) in August at point 4. Phytoplankton biomass indicates an eutrophic estuary as Chlorophyll-a varied from 13.01 to 112.88 mg m-3, probably due to marine shrimp farm effluents. It was possible to identify species strongly indicative of the environment, through analysis of indicator species (IndVal), and their relations with the...

O objetivo deste estudo foi avaliar a dinâmica microfitoplanctônica e os parâmetros ambientais no estuário do rio Curuperé, localizado em um ecossistema de manguezal na Amazônia. Foram realizados dez pontos de amostragem, utilizando amostras de água superficial para análises qualitativas (rede com malha de 20 µm) e quantitativa do microfitoplâncton, bem como para determinação de clorofila a, temperatura da água superficial, turbidez, salinidade e pH. As amostragens foram realizadas em quatro meses: fevereiro, maio, agosto e novembro, sendo os dois primeiros correspodentes ao período chuvoso e os dois últimos, ao seco. Foram observadas diferenças significativas entre os meses e relacionadas à posição ao longo do eixo estuarino para diversidade, eqüitabilidade e dominância específica na comunidade microfitoplanctônica. Foram identificados 212 com dominância de Bacillariophyta (149 taxa), seguido por Myzozoa (29 taxa). O microfitoplâncton variou de 7.700 ind L-1, (maio, ponto 1) a 343.800 ind L-1, em agosto (ponto 4). A diatomácea Cymatosira belgica foi a espécie dominante, seguida por Dimeregramma minor (maiores picos de 180.600 ind L-1 e 120.400 ind L-1, respectivamente) em agosto no ponto 4. Os valores de clorofila a permaneceram altos ao longo do ano variando de 13,01 a 112,88 mg m-3, provavelmente devido aos efluentes de fazenda de camarões marinhos. Foi possível identificar...

The state of global scientific literature on chlorophyll-A / O estado da arte da literatura científica global sobre clorofila-A

Chlorophyll is a green pigment common to all photosynthetic cells of autotrophic organisms in aquatic or terrestrial environments. Techniques used to quantify this pigment include fluorescence, UV spectrophotometer, chromatography, HPLC, and remote sensing. Determination of the photosynthetic pigment chlorophyll - a (Chl-a), has been used widely in many areas of science. The present study investigated the state of the global scientific literature on Chl-a, determining the countries, approaches, and environments where Chl-a has been studied and the geographic scale used. To obtain this scientometric information, we conducted a study from the Scopus database over a 21-year period from 1990 through 2011. This period saw significant increases in the number of publications (r=0.84 and P< 0.001), different journals where publications appeared (160 journals), major papers with a multidisciplinary character, and a predominance of descriptive approaches with studies conducted in aquatic and marine habitats at a regional scale. The country with the highest number of publications was China (21.64% of total papers; location of study), and the USA had the highest number of authors (19.52% of total papers). The main determining factor for publications was socioeconomic (according to model selection criteria; AIC). This study highlight the multidisciplinary use of Chl-a, and may give some directions to new studies about this pigment.

A clorofila é um pigmento verde, comum em todas as células fotossintéticas de organismos autotróficos, de ambientes aquáticos ou terrestres. As técnicas mais utilizadas para quantificar esse pigmento são a fluorescência, a espectrofotometria de UV, a cromatografia HPLC e o uso de sensores remotos. Assim, a determinação do pigmento fotossintético chlorofila-a (Chl-a), tem sido utilizada amplamente em diversas áreas da ciência. Portanto, o objetivo deste trabalho foi investigar o estado da arte da literatura científica para o pigmento fotossintetizante clorofila-a, determinando os países de estudo, os fatores socioeconômicos- ambiental que estão ligados ao estudo de clorofila ­a, abordagens utilizadas, e ainda, os ambientes estudados, a escala geográfica e as revistas. Para obter tais informações realizou-se um estudo cienciométrico, a partir da base de dados Scopus, numa escala temporal de 21 anos (entre 1990 e 2011). Os padrões encontrados para as pesquisas com Chl-a são o aumento temporal de publicações (r=0.84 and P<0.001), a diversidade de revistas que publicaram estudos sobre o assunto (160 revistas), maior número de publicações com caráter multidisciplinar, predomínio de estudos com abordagens descritivas realizados em ambientes aquáticos e marinhos e estudos em escala geográfica regional. A China foi o país mais estudado com 21,64% do total de artigos publicados, e os estadunidenses lideraram com o maior número de publicações sobre este assunto (19,52% do total de artigos publicados). Utilizando o critério de seleção de modelos de Akaike observou-se que as publicações são impulsionadas pelo fator socioeconômico PIB. Este estudo demonstrou o uso multidisciplinar da Chl-a e pode indicar algumas direções para novos estudos com esse pigmento.