Denise Rivera Tenenbaum

Environmental and Sanitary Conditions of Guanabara Bay, Rio de Janeiro.

Guanabara Bay is the second largest bay in the coast of Brazil, with an area of 384 km2. In its surroundings live circa 16 million inhabitants, out of which 6 million live in Rio de Janeiro city, one of the largest cities of the country, and the host of the 2016 Olympic Games. Anthropogenic interference in Guanabara Bay area started early in the XVI century, but environmental impacts escalated from 1930, when this region underwent an industrialization process. Herein we present an overview of the current environmental and sanitary conditions of Guanabara Bay, a consequence of all these decades of impacts. We will focus on microbial communities, how they may affect higher trophic levels of the aquatic community and also human health. The anthropogenic impacts in the bay are flagged by heavy eutrophication and by the emergence of pathogenic microorganisms that are either carried by domestic and/or hospital waste (e.g., virus, KPC-producing bacteria, and fecal coliforms), or that proliferate in such conditions (e.g., vibrios). Antibiotic resistance genes are commonly found in metagenomes of Guanabara Bay planktonic microorganisms. Furthermore, eutrophication results in recurrent algal blooms, with signs of a shift toward flagellated, mixotrophic groups, including several potentially harmful species. A recent large-scale fish kill episode, and a long trend decrease in fish stocks also reflects the bay’s degraded water quality. Although pollution of Guanabara Bay is not a recent problem, the hosting of the 2016 Olympic Games propelled the government to launch a series of plans to restore the bay’s water quality. If all plans are fully implemented, the restoration of Guanabara Bay and its shores may be one of the best legacies of the Olympic Games in Rio de Janeiro.

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).

Small time scale plankton structure variations at the entrance of a tropical eutrophic bay (Guanabara Bay, Brazil)

The dynamics of the plankton compartments at the entrance of Guanabara Bay (SE Brazil) were assessed during a short-term temporal survey to estimate their trophic correlations. Size-fractioned phytoplankton (picoplankton: 20µm) biomass and photosynthetic efficiency, composition and abundance of the auto-and heterotrophic nano-and microplankton, and mesozooplankton were evaluated at a fixed station for 3 consecutive days at 3-h intervals, in the surface and bottom (20m) layers. The variability of almost all plankton compartments in the surface layer was directly dependent on temperature, indicating the great influence of the circulation at the entrance of the bay on plankton structure. In the surface layer, the mesozooplankton seems to be sustained by both autotrophic nano-and picoplankton, this last being channeled through the microzooplankton. Near the bottom, both auto-and heterotrophic microplankton are probably supporting the mesozooplankton biomass. Our findings thus suggest that the entrance of Guanabara bay presents a multivorous food web, i.e., a combination of both grazing and microbial trophic pathways.

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 Baia de Guanabara (Brasil), estuario tropical com serios problemas ambientais, mas pouco se sabe sobre o protozooplâncton. Preenchendo esta lacuna, a composicao e abundância do protozooplâncton (ciliados, flagelados heterotroficos) foram investigadas em 2000, por meio de amostragens subsuperficiais, quinzenais, em dois locais com qualidade distinta de agua (Urca - entrada da baia, aguas mais salinas e limpas; Ramos - regiao mais interna, aguas hipereutroficas e menos salinas). A densidade na Urca (103-105 cel.L-1) foi inferior a de Ramos (104-105 cel.L-1), com sazonalidade para o nanoplâncton e protozooplâncton mais evidente, menores valores durante o periodo mais frio (abril a agosto). Pequenos dinoflagelados (20-30 mm) dominaram mais de 50% das amostras. A abundância e composicao refletiram o distinto estado trofico na baia (analise fatorial de correspondencia: 56%). Ciliados nao oligotriqueos (Vorticellidae, Dysteriidae, Didiniidae) e Gymnodiniaceae foram representativos de Ramos na estacao quente-umida (outubro - marco), enquanto tintinideos (Codonellopsidae, Metacyclididae, Tintinnidae, Undellidae) e dinoflagelados (Oxyphysaceae, Ebriidae, Protoperidiniaceae, Noctilucaceae) representativos da Urca, principalmente na estacao fria-seca (abril - setembro). Este primeiro estudo descritivo, fundamental para o entendimento das relacoes na teia alimentar microbiana, revelou o protozooplâncton como bom indicador das condicoes da qualidade da agua da baia.

Environmental Processes, Biodiversity and Changes in Admiralty Bay, King George Island, Antarctica

The isolation of Antarctica from South America during the Oligocene (~35 mya) formed the Southern Ocean, generated the northward flow of the Atlantic Antarctic Bottom Water, and numerous unique geological and oceanic processes (e.g. an active spreading centre in the Bransfield Strait, ridge trench collision, gas hydrates on modern sediments, and complex circulation) along the northern end of the Antarctic Peninsula in particular (Barker and Burrell 1982; Pearse et al. 2001; Barker and Thomas 2004; Thomson 2004; Turner et al. 2009).

Shifts in microphytoplankton species and cell size at Admiralty Bay, Antarctica

Abstract Phytoplankton (>15 µm) was investigated in three shallow coastal areas at Admiralty Bay (AB) between the summers of 2002–03 and 2008–09. Phytoplankton abundance was low (103 cells l-1) and, over time, the prevailing cell size decreased due to a shift in phytoplankton dominant species from diatoms to dinoflagellates. In situ and remote sensing data showed that oscillations in sea surface temperature, precipitation, ice formation/melting, irradiance (cloud cover) and bottom circulation (indexed by the Antarctic Oscillation Index; AAO) were shown to govern the structure of the phytoplankton. Under negative AAO, diatoms prevailed, with the dominance of large (>80 µm) benthic diatoms (e.g. Corethron pennatum and Navicula directa) in periods of low production (102 cells l-1 in 2002–03), and medium-sized (31–80 µm) centrics (e.g. Thalassiosira spp. and Stellarima microtrias) when the abundance was higher (104 cells l-1 in 2003–04). Conversely, positive AAO led to the co-dominance of dinoflagellates and planktonic diatoms (e.g. Pseudo-nitzschia spp.) in the summers of 2007–08 and 2008–09. These results suggest that the AAO can be a good predictor of phytoplankton in coastal areas around the western Antarctic Peninsula, and may help our understanding of changes in other trophic levels of the food web.

Flagellates Versus Diatoms: Phytoplankton Trends in Tropical and Subtropical Estuarine-Coastal Ecosystems

Attempts to provide general patterns of phytoplankton and their regulating factors benefit from ecosystem comparisons, but these are strongly biased toward high-latitude environments of the northern hemisphere (> 20°N). In the present study, we compare the phytoplankton biomass and composition variability in two coastal environments in the southern hemisphere, the tropical Guanabara Bay, GB (23°S), and the subtropical Patos Lagoon Estuary, PLE (32°S), located on the South American southeast coast at the state of Rio de Janeiro and Rio Grande do Sul, respectively. These environments present contrasting features regarding the magnitude of anthropic impacts, the watershed size, geomorphology, and hydrology. Our goal was to identify the main factors that regulate the phytoplankton biomass and composition comparing data obtained at monthly intervals between the years 2011 and 2012 at a single station located in an area of significant water exchange in each environment. Surface water temperature, salinity, inorganic dissolved nutrients, chlorophyll a, phytoplankton biomass (carbon) and composition were analyzed. Phytoplankton biomass in the GB and PLE was dominated, respectively, by flagellates and diatoms, whereas cyanobacteria were more important in the former. Salinity was about twofold higher in the GB (mean 32.6 ± 1.5) than PLE (mean 15.4 ± 9.1) and, together with nutrient concentrations and their proportions, largely explained the observed different communities and much higher biomass in GB. GB presented strong eutrophication signals, with high ammonium and phosphate and lower, closer to limitation, silicate concentration. In contrast, high silicate concentration favored the predominance of diatoms in the PLE. Despite large environmental differences between both environments, the chlorophyll a presented a rather similar seasonal pattern, with maxima in austral summer/autumn and spring in both ecosystems. We suggest the seasonal pattern was associated to the incident light variation, but this hypothesis should be further explored.

SIZE-FRACTION, TROPHIC CATEGORIES AND MORPHOTYPES STRUCTURE OF PLANKTON SMALLER THAN 20 ¼m DURING THE AUSTRAL SUMMER (ADMIRALTY BAY, KING GEORGE ISLAND, WAP)

e density and distribution of plankton community smaller than 20 μm in Admiralty Bay (King George Island, Antarctica) were studied at three sampling sites during the austral summer of 2013/2014 (two surveys at the beginning – early summer, two at the end – late summer). e aim was to identify the environmental factors that in uence their variability. Salinity (34.2 ± 0.1) and temperature (0.47 ± 0.24°C) showed little variation in late summer, but in general, the concentration of dissolved nutrients increased towards this period. Organisms smaller than 10μm showed the higher contribution (74%) for Chlorophyll a concentration. Picoplankton (<2 μm), dominated by basically heterotrophs (98.5%), had density of 3.9 ± 1.8 x108 cell L-1. e fraction between 2 and 20 μm, dominated by autotrophs (60%), presented densities up to 3.6 ± 1.2 x106 cell L-1. is community was dominated by cocci and spherical morphotypes. Our results suggest that: (i) cell density increase along the study period followed nutrient and organic matter inputs; (ii) lower densities relative to 2009-2011 summers were related to lower temperatures and melting rates, besides predation forces, demonstrating the complex spatial-temporal relationships that take place between plankton community and environmental parameters at Admiralty Bay coastal zone.

PLANKTONIC SYSTEM OF GUANABARA BAY: A REVIEW

Guanabara Bay, one of the most eutrophic tropical systems in tire world, receives large loads of urban and industrial wastes. Its hydrobiology shows temporal trends according to seasonal variations determined by the rainny summer and spatial trends associated to a tidally induced current pattern that create horizontal and vertical gradients. Human impact is strongest along the shores in the inner reaches of the Bay that present high ammonia and phosphorus concentrations (? 650 ?M and ? 308 ?M), and low, transparence (