Diversions of the Ribeira River Flow and Their Influence on Sediment Supply in the Cananeia-Iguape Estuarine-Lagoonal System (SE Brazil)

Abstract

The Cananéia-Iguape system is a combined estuarine-lagoonal sedimentary system, located along the SE coast of Brazil. It consists of a network of channels and islands oriented mainly parallel to the coast. About 165 years ago, an artificial channel, the Valo Grande, was opened in the northern part of this system to connect a major river of the region, the Ribeira River, to the estuarine-lagoon complex. The Valo Grande was closed with a dam and reopened twice between 1978 and 1995, when it was finally left open. These openings and closures of the Valo Grande had a significant influence on the Cananéia-Iguape system. In this study we present mineralogical, chemical, palaeomagnetic, and geochronological data from a sediment core collected at the southern end of the 50 km long lagoonal system showing how the phases of the opening and closure of the channel through time are expressed in the sedimentary record. Despite the homogeneity of the grain size and magnetic properties throughout the core, significant variations in the mineralogical composition showed the influence of the opening of the channel on the sediment supply. Less mature sediment, with lower quartz and halite and higher kaolinite, brucite, and franklinite, corresponded to periods when the Valo Grande was open. On the other hand, higher abundance of quartz and halite, as well as the disappearance of other detrital minerals, corresponded with periods of absence or closure of the channel, indicating a more sea-influenced depositional setting. This work represented an example of anthropogenic influence in a lagoonal-estuarine sedimentary system, which is a common context along the coast of Brazil.

Seismic Stratigraphy of Trapandé Bay (Southern Brazil) to Study Sea-Level Changes and Deposition Evolution in the Upper Quaternary

“…It has a great environmental and economic importance, as it is nursery for several species (Mahiques et al, 2013). In addition, the whole system suffered huge changes since the 19th century after the opening of the Valo Grande artificial channel, which connected the Ribeira de Iguape River to the system (Geobrás, 1966;Cornaggia et al, 2018).…”

“…The Cananéia-Iguape sedimentary plain is bordered by a Precambrian crystalline metamorphic basement arc, named Serra do Mar which is bounded to the Açungui Group (Souza et al, 1996;Tessler, 1982) and is marked by uplifting of a series of Mesozoic intrusive alkaline complexes. As an example, the Cananéia alkaline rock massif (São João Hill) is a small elevation densely vegetated, with 137 m maximum height and about 450 m² area (Cornaggia et al, 2018). Furthermore, Comprida Island also hosts a smaller rocky massif namely Morrete (Riccomini, 1995).…”

Seasonal arsenic in catfish (Siluriformes, Ariidae) and the hydrochemical conditions of two areas in a Ramsar site on the Brazilian coast

“…This part of the estuarine complex is better preserved than the northern area of the estuarine complex system because it is significantly influenced by the ocean, which conserves the natural conditions attributed to tide influxes and sea hydrodynamics (Braga & Chiozzini 2008. The northern region of this estuary receives a high freshwater inflow due to its proximity to the Ribeira de Iguape River, which brings with it an inflow of different materials from the continent as it passes through the Valo Grande (an artificial drainage channel) (Cornaggia et al 2018).…”

Morphometric analysis of lapillus otoliths in two estuarine bioindicator catfish (Siluriformes, Ariidae) from a marine protected area in Brazil

“…Thus, studies with bioindicator species, such as the Ariidae representatives C. spixii and G. genidens (Azevedo et al, 2009;Azevedo et al, 2012;Maciel et al, 2018), are very important, since they can be used to improve knowledge about life history, growth, and habitat use (Avigliano et al, 2014), in association with subcellular biochemical, genetic, and histological responses (Chovanec et al, 2003;Azevedo et al, 2013). Although the CIELC is anthropogenically influenced by continental discharges in the northern area, by the Ribeira de Iguape River inflow via Valo Grande (Mahiques et al, 2009(Mahiques et al, , 2013Cornaggia et al, 2018), this estuarine system still has characteristics of a healthy ecosystem based on its hydrobiogeochemical characteristics (Chiozzini et al, 2010;Amaral et al, 2021). Therefore, the use of otolith measurements as a predictor of temporal changes in fish from the CIELC is highly valid.…”