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

Abstract

This paper focuses on the nutrient dynamics of a tropical estuary on the northeastern Brazilian coast, studied using the LOICZ biogeochemical budgeting protocol. We describe the methodology and assumptions underlying this model. Input data (monthly for rainfall, evaporation, river discharge, and concentrations of salt, phosphorus and nitrogen) were obtained during field campaigns in the Barra das Jangadas Estuary (BJE) over a 5 years period (1999 to 2003). Mass balance results indicate large inputs of nutrients to the system. The model shows that the seasonal variation of the Net Ecosystem Metabolism (NEM) indicates that the system passes from a stage of organic matter liquid production and mineralization during the dry season (-0.5 mmoles C m −2 d −1 ) to liquid mineralization during the rainy season (-19 mmoles C m −2 d −1 ). We suggest that the system varies slightly between autotrophy and heterotrophy during the year due to the rainfall regime, human activities in the basin (density population and sugarcane plantations), and associated DIP riverine loads. High per capita loads of N and P indicate a high population density and high runoff. The application of flux balance modeling was useful to understand the nutrient dynamics of this typical small tropical estuary.

Trophic dynamics (Dissolved Inorganic Nitrogen-DIN and Dissolved Inorganic Phosphorus-DIP) in tropical urban estuarine systems during periods of high and low river discharge rates

“…the recife system exhibited an eutrophic system under both types of discharge, indicating a poor environmental quality and high productivity with excess nutrients associated with high concentrations of chlorophyll-a, which was primarily observed during the summer months. The Barra das Jangadas and Timbó systems bear likely similarities to these results if we consider the work performed by Noriega and Araujo (2011) and Branco (2007) in the Barra das Jangadas Basin and by Grego et al (2004) in the Timbó River.…”

“…Most urban waste therein lacks adequate treatment, and both agriculture and livestock farming practices have intensified along the coastal region. Some isolated studies have already suggested that some of these areas are showing signs of incipient eutrophication (Guenther et al 2016, Noriega and Araujo 2011. The systems adjacent to the RMR, including the Capibaribe River, Beberibe River, Tejipió River, Jaboatão River, Pirapama River, Pina Basin, and Timbó River, have experienced important ecosystem changes due to anthropogenic influences during the last century (Noriega 2010).…”

Seasonal dissolved inorganic nitrogen and phosphorus budgets for two sub-tropical estuaries in south Florida, USA

“…It is likely that the increased concentration of DIN in the CRE during the wet season was due to heightened rates of remineralization and denitrification in response to increased DIN loading and primary production. In contrast, estuaries in Australia (Lake Illawarra), Taiwan (Tsesngwen Estuary), and Italy (several lagoons) responded to DIN loading by consuming DIN on annual timescales (Que et al, 2003;Hung and Huang, 2005;Giordani et al, 2008, Noriega andAraujo, 2011). Compared to the CRE, the response of the SLE to DIN loading was less clear with N 2 fixation in excess of denitrification for all seasonal budgets.…”

Alkalinity, inorganic carbon and CO2 flux variability during extreme rainfall years (2010-2011) in two polluted tropical estuaries NE Brazil

“…The land use activity in these watersheds is primarily urban and industrial, including areas of sugarcane monoculture, and some vestigial areas of Atlantic Forest and mangrove forest (CPRH, 2011). Several studies have identified an increase in nutrient concentrations, human eutrophication and algal blooms in this region in recent years (Travassos et al, 1993;Koening et al, 1995;Feitosa et al, 1999;Noriega and Araujo, 2009;Noriega and Araujo, 2011;Flores Montes et al, 2011;Guenther et al, 2015) and organic pollution Travassos et al, 2016).…”