Auto- and heterotrophic nanoplankton and filamentous bacteria of Guanabara Bay (RJ, Brazil): estimates of cell/filament numbers versus carbon content

Variações do nanoplâncton (2-20µm) e bactérias filamentosas (diâmetro: 0.5-2.0 µm) da Baía de Guanabara (RJ, Brasil) são apresentadas, considerando densidade celular e biomassa de autótrofos e heterótrofos. A meta deste trabalho é contribuir para uma futura modelagem da dinâmica trófica neste sistema. Amostras subsuperficiais de água foram coletadas semanalmente durante um ano em dois pontos: Urca (próximo à entrada, mais salino, eutrófico) e Ramos (no interior, menos salino, hipertrófico). Foi feita análise por microscopia de epifluorescência, com densidade celular convertida para biomassa através do biovolume celular. A concentração do nanoplâncton total foi alta (10(8)cel.l-1) na maioria das amostras (>;57%) e das bactérias filamentosas variou de 10(5) a 10(8)fil.l-1. A densidade de autótrofos em Ramos foi uma ordem de grandeza superior tanto para o nanoplâncton (Md: 10(8)cel.l-1 em Ramos e 10(7)cel.l-1 na Urca) quanto para as bactérias filamentosas (Md: 10(6)fil.l-1 em Ramos e 10(5)fil.l-1 na Urca). A biomassa autotrófica do nanoplâncton (Md: 10³µgC.l-1 em Ramos e 10¹µgC.l-1 na Urca) e das bactérias filamentosas (Md: 28µgC.l-1 em Ramos e 1,4µgC.l-1 na Urca) seguiu o mesmo padrão. A contribuição relativa de autótrofos aumentou após a conversão para biomassa. Uma tendência temporal foi evidenciada para as bactérias filamentosas em ambos os pontos e, para o nanoplâncton autotrófico, em Ramos, com valores máximos no período chuvoso (primavera-verão).Variations of nanoplankton (2-20 µm) and filamentous bacteria (diameter: 0.5-2.0 µm) of Guanabara Bay (RJ, Brazil) are presented, considering cell density and carbon content of auto- and heterotrophs. Our goal is to contribute to future modeling of local trophic dynamics. Subsurface water samples were taken weekly during the year 2000 at two sites: Urca (close to the entrance, more saline, eutrophic) and Ramos (inner area, less saline, hypertrophic). Microscopic analysis was done by epifluorescence and cell density was converted to biomass through cell biovolume. Total nanoplankton was about 10(8) cells.l-1 in most samples (>;57%), and total filamentous bacteria densities varied from 10(5) to 10(8) fil.l-1. Autotroph density was one order of magnitude higher at Ramos, both for nanoplankton (Md: 10(8)cells.l-1 at Ramos and 10(7)cells.l-1 at Urca) and for filamentous bacteria (Md: 10(6) fil.l-1 at Ramos and 10(5) fil.l-1 at Urca). The same was observed for autotrophic biomass (Md: 10³µgC.l-1 at Ramos and 10¹µgC.l-1 at Urca for nanoplankton; Md: 28µgC.l-1 at Ramos and 1.4µgC.l-1 at Urca for filamentous bacteria). The relative contribution of autotrophs increased after conversion to biomass. Seasonal variation was conspicuous for filamentous bacteria at both sites and for nanoplankton only at Ramos, with maximum autotrophic abundances during the rainy period (spring-summer)

Protozooplankton characterization of two contrasting sites in a tropical coastal ecosystem (Guanabara Bay, RJ)

Muito tem sido investido para entender a dinâmica do plâncton da Baía de Guanabara (Brasil), estuário tropical com sérios problemas ambientais, mas pouco se sabe sobre o protozooplâncton. Preenchendo esta lacuna, a composição e abundância do protozooplâncton (ciliados, flagelados heterotróficos) foram investigadas em 2000, por meio de amostragens subsuperficiais, quinzenais, em dois locais com qualidade distinta de água (Urca - entrada da baía, águas mais salinas e limpas; Ramos - região mais interna, águas hipereutróficas e menos salinas). A densidade na Urca (10³-10(5) cel.L-1) foi inferior à de Ramos (10(4)-10(5) cel.L-1), com sazonalidade para o nanoplâncton e protozooplâncton mais evidente, menores valores durante o período mais frio (abril a agosto). Pequenos dinoflagelados (20-30 mm) dominaram mais de 50% das amostras. A abundância e composição refletiram o distinto estado trófico na baía (análise fatorial de correspondência: 56%). Ciliados não oligotríqueos (Vorticellidae, Dysteriidae, Didiniidae) e Gymnodiniaceae foram representativos de Ramos na estação quente-úmida (outubro - março), enquanto tintinídeos (Codonellopsidae, Metacyclididae, Tintinnidae, Undellidae) e dinoflagelados (Oxyphysaceae, Ebriidae, Protoperidiniaceae, Noctilucaceae) representativos da Urca, principalmente na estação fria-seca (abril - setembro). Este primeiro estudo descritivo, fundamental para o entendimento das relações na teia alimentar microbiana, revelou o protozooplâncton como bom indicador das condições da qualidade da água da baía.Much time and resources have been invested in understanding plankton dynamics in Guanabara Bay (Brazil), but no attention has been devoted to the protozooplankton. To fulfill this lacuna, abundance and composition of protozooplankton were investigated from January to December - 2000 in fortnightly surface water samplings at two distinct water quality sites (Urca - closer to the bay entrance, more saline and cleaner waters; Ramos - inner reaches, hypereutrophic waters). The density at Urca (10³ - 10(5) cell.l-1) was one to three orders of magnitude lower than at Ramos (10(4) - 10(5) cell.l-1). A seasonal trend for nanoplankton and protozooplankton was more evident at Urca, but both sites had lower densities during the colder period. Small heterotrophic dinoflagellates (20-30 mm) were dominant in over 50% of the samples. The protozooplankton abundance and composition reflected the distinct trophic conditions states found at the bay. During the wet-warm season, non-oligotrich ciliates were representative of Ramos site with Gymnodiniaceae dinoflagellates, while tintinnids and heterotrophic dinoflagellates were predominantly found at Urca mainly during the dry-cold season. This first descriptive study towards the understanding of the intricate relationships among the microbial food web components reveals that protozooplankton can be a good indicator of water quality conditions at the bay

Auto- and heterotrophic nanoplankton and filamentous bacteria of Guanabara Bay (RJ, Brazil): estimates of cell/filament numbers versus carbon content

Variations of nanoplankton (2-20 µm) and filamentous bacteria (diameter: 0.5-2.0 µm) of Guanabara Bay (RJ, Brazil) are presented, considering cell density and carbon content of auto- and heterotrophs. Our goal is to contribute to future modeling of local trophic dynamics. Subsurface water samples were taken weekly during the year 2000 at two sites: Urca (close to the entrance, more saline, eutrophic) and Ramos (inner area, less saline, hypertrophic). Microscopic analysis was done by epifluorescence and cell density was converted to biomass through cell biovolume. Total nanoplankton was about 10(8) cells.l-1 in most samples (>57%), and total filamentous bacteria densities varied from 10(5) to 10(8) fil.l-1. Autotroph density was one order of magnitude higher at Ramos, both for nanoplankton (Md: 10(8)cells.l-1 at Ramos and 10(7)cells.l-1 at Urca) and for filamentous bacteria (Md: 10(6) fil.l-1 at Ramos and 10(5) fil.l-1 at Urca). The same was observed for autotrophic biomass (Md: 10³µgC.l-1 at Ramos and 10¹µgC.l-1 at Urca for nanoplankton; Md: 28µgC.l-1 at Ramos and 1.4µgC.l-1 at Urca for filamentous bacteria). The relative contribution of autotrophs increased after conversion to biomass. Seasonal variation was conspicuous for filamentous bacteria at both sites and for nanoplankton only at Ramos, with maximum autotrophic abundances during the rainy period (spring-summer)

The phytoplankton biodiversity of the coast of the state of São Paulo, Brazil

The objective of this study is to compile the inventory of nearly 100 years of research about the phytoplankton species cited for the coast of the state of São Paulo, Brazil. A state-of-the-art study on the local biodiversity has long been needed to provide a baseline for future comparisons. This type of data is scattered in old scientific journals and in the so-called "grey literature", and are in need of nomenclature updating. Twenty-six publications are considered. The earliest sampling record is from 1913 (?) and the most recent from 2002. This checklist compiled from the literature was complemented with primary data collected between August 2004 and July 2006, recent surveys of the surf-zone of 20 beaches located along the coast and of a mariculture farm at the Cocanha Beach, Caraguatatuba. The complete species list includes 572 taxa: most are diatoms (82%), seconded by dinoflagellates (16%), with a minor contribution of silicoflagellates, coccolithophorids, ebriideans and cyanobacteria. The most investigated areas were: Ubatuba, São Sebastião, Santos and Cananéia. The recent surveys have a broader spatial coverage. The objectives of the studies have changed over the years from purely taxonomic to process-oriented investigations. Therefore, the longest species lists and most first records for the area were published before the 1980's and later publications, even those in which cell counts were performed, mention only the most abundant/frequent species. Electron microscopy was used for the first time in the present surveys, and new records include 38 diatoms, 42 dinoflagellates, 1 silicoflagellate, 1 ebriidean and 2 cyanobacteria. The use and interpretation of this species list require the perception of some constraints. It is not our role to question the identification made by other researchers. On the other hand, the ability to sample, analyze and identify species has evolved over the years and some considerations in this regard are presented