Land-ocean fluxes in the Paranaguá Bay estuarine system, southern Brazil

Abstract

A B S T R A C TA worldwide modeling effort has been proposed by the LOICZ (Land-Ocean Interactions in the Coastal Zone) Program to foster the acquisition of intercomparable data on land-ocean fluxes in estuaries and continental shelf ecosystems from all continental margins. As part of the South American component of this initiative, we present flux estimates of water, salt, dissolved inorganic phosphorus (DIP), dissolved inorganic nitrogen (DIN) and plankton for the estuarine system of Paranaguá Bay, southern Brazil, based on the LOICZ modeling approach and local data obtained during the 1990's. This system is strongly influenced by a seasonal meteorological cycle, represented by the rainy/summer and dry/winter periods. Semi-diurnal tides of up to the 2.7-m range are responsible for the short time-scale dynamics. The model indicated a potential water export to the adjacent coast of up to 7 x 10 6 m 3 d -1 in the dry season, and 28 x 10 6 m 3 d -1 during the rainy season. The system exhibits seasonal and spatial variations in DIP and DIN fluxes. ∆DIP amounted to +2.3 x 10 6 mol P yr -1 and ∆DIN to -2.7 x 10 6 mol N yr -1 , suggesting that net production of phosphate and consumption of inorganic nitrogen predominate throughout in the system. Fluxes and therefore export of DIN and eespecially of DIP are higher in the rainy season. Stoichiometric estimates based on the C:N:P ratios of the reacting particulate organic matter (mangrove and plankton detritus) suggest that net denitrification predominates all over the bay, with values between -24.3 and -10.6 x 10 6 mol N year -1 . Estimated seaward outflows had little effect upon the fate of the phyto-and zooplankton biomass in different sectors of the bay. This is exemplified by the low net export of algal production from the upper to the middle sectors of the estuary. R E S U M OUm esforço global de modelagem foi proposto pelo Programa LOICZ (Land-Ocean Interactions in the Coastal Zone) para promover a aquisição de dados comparáveis sobre fluxos continente-oceano em ecossistemas estuarinos e de plataforma em todos os continentes. Como parte do componente sulamericano desta iniciativa, apresentamos neste trabalho estimativas de fluxo de água, sal, fósforo inorgânico dissolvido (DIP), nitrogênio inorgânico dissolvido (DIN) e plâncton para o sistema estuarino da Baía de Paranaguá, obtidas a partir da aplicação de modelos sugeridos pelo programa LOICZ. Este sistema é fortemente influenciado por um ciclo meteorológico sazonal, representado pelos períodos chuvosos de verão e secos de inverno. As marés semidiurnas, com variação de até 2,7 m, são responsáveis pela dinâmica estuarina de curta escala temporal. Nossos resultados indicam uma exportação potencial de água para a área costeira adjacente de até 7 x 10 6 m 3 d -1 no período seco e mais de 28 x 10 6 m 3 d -1 no período chuvoso. O sistema exibe variações sazonais e espaciais nos fluxos de DIP e DIN. O ∆DIP atingiu +2.3 x 10 6 mol P ano -1 e o ∆DIN to -2.7 x 10 6 mol N ano -1 , sugerindo que a produção líquida de fosfato...

Phytoplankton dynamics in a highly eutrophic estuary in tropical Brazil

“…Studies carried out by Marone et al (2005) close to a port in the Paranaguá Bay suggest that eutrophication processes and their consequences (e.g., oxygen depletion) tend to be more intense during the net heterotrophic rainy period and care should be taken to minimize the effect of the sewage load on the environment, especially during the rainy season.…”

Nutrient budgets (C, N and P) and trophic dynamicsof a Brazilian tropical estuary: Barra das Jangadas

“…Water quality also varies, particularly as seasonal and annual climatic patterns change. In these systems tracking environmental changes can be challenging, and distinguishing impacts caused by human actions from natural variations can be even more difficult (Marone et al 2005). Under normal estuarine spatial and temporal constraints, reactive materials, such as nutrients, behave non-conservatively due to modifications by biological recycling and chemical transformations acting independently of simple physical advection and mixing (Dale and Prego 2005).…”

Environmental water quality assessment in Guaratuba bay, state of Paraná, southern Brazil

“…1) is located around the coordinates 25°51.8'S and 48°38.2'W having a surface water area of 50.19 km 2 and a mean depth of 3 m. Around 24% of the bay is shallow, the maximum depth of 27 m being observed at the system's mouth (MARONE et al, 2004) which is formed by two rocky points 500 m apart. From its connection with the Atlantic Ocean, the system widens inwards for 15 km, harboring many sand banks.…”

“…Guaratuba Bay is surrounded by seagrass and mangrove vegetation, which are more extensive along the northern margin of the estuary, whereas its southern margin is largely occupied by urban settlements and agricultural enterprises (MARONE et al, 2004).…”

“…The hydrodynamic scenario of Guaratuba Bay is presented by Marone et al (2004). The system has strong currents (more than 2 m s -1 at the mouth), and semi-diurnal tides of up to 1.5 m range (0.65 m at neap tide).…”