Mollusks as indicators of historical changes in an estuarine-lagoonal system (Cananéia-Iguape, SE Brazil)

Abstract

Mollusks recovered from three cores taken from the Cananéia-Iguape estuarine-lagoonal system (São Paulo State, Brazil) were studied. The sampled sediments cover a period beginning approximately two centuries ago and end at the present, including a period when the system suffered significant changes of anthropogenic origin – that is, the construction of an artificial channel connecting the lagoon with a nearby river and with the resulting input of fresh water and contaminants generated from mining activity upstream. The mollusk composition reflects these changes. The more abrupt changes in this composition coincide with the opening of the Valo Grande artificial channel in 1852. Another significant but minor change event was verified for around 1977± one year in areas that were not previously affected, perhaps showing the effect of the closing and reopening of the channel.

The Role of Paleoecology in Restoration and Resource Management—The Past As a Guide to Future Decision-Making: Review and Example from the Greater Everglades Ecosystem, U.S.A

“…These studies revealed differences in urban vs. rural areas and also demonstrated the response of the biota at some sites to decreases in waste water discharge, information that can be used to guide the EU's Water Framework Directive (Weckström, 2006;Weckström et al, 2007). In southeastern Brazil, Martínez et al (2013) identified distinct changes in benthic assemblages in the Cananéia-Iguape estuarine-lagoonal system associated with construction of the Valo Grande channel and diversion of freshwater. Analysis of cores from Elkhorn Slough estuary, central California, U.S.A., indicated changes in marsh vegetation that corresponded to changes in sedimentation rates (Watson et al, 2011).…”

Morphometric analysis of Littoraria angulifera (Caenogastropoda) in estuarine regions of northeastern Brazil

“…This group includes mesogastropods of the family Littorinidae (Caenogastropoda), like species of the genus Littoraria Gray, 1833, that adapted to live in these environments (Reid, 1986;Merkt and Ellison, 1998). Because they often present morphological responses to the specific environment they occupy, as well as to human impacts, these mollusks are becoming attractive for use in environmental monitoring (Tanaka and Maia, 2006;Melo et al, 2012;Costa et al, 2013;Martínez et al, 2013). Although mesogastropods are considered less sensitive than neogastropods to some types of chemical contamination (Bauer et al, 1995), these are interesting alternatives to places where there are no neogastropods, as is the case of mangroves.…”

“…Within the assumptions for bioindication referred by Mccarty and Munkittrick (1996), L. angulifera meets several selection criteria for estuaries and mangroves monitoring, among them, easy collection and manipulation and its conspicuous presence in these systems. Nevertheless, few studies have used it as a sentinel species of environmental quality in mangroves/ estuaries (Martínez et al, 2013). Recent studies in Southeast (Costa et al, 2013) and Northeast Brazilian coast (Zeidan et al, 2018), suggest the feasibility of using L. angulifera as bioindicator for organotin contamination that still been used in antifouling paints of boats.…”

From sambaquis (shell mounds) to plastic debris: a summary of the geological imprint of human occupation in the coast of São Paulo (Southeast Brazil)

“…From the original dimensions of 4.4 meters wide per 2 meters the channel presently shows widths of approximately 250 meters per depths of about 7 meters. Nowadays, about 60% of the freshwater and suspended sediments carried by the Ribeira River, the most important coastal river in São Paulo, reach the lagoonal system, with a consequent modification of environmental conditions (Martinez et al, 2013) and intense siltation (De Mahiques et al, 2014), forming several islands at the mouth of the artificial channel (figures 4 and 5).…”

“…From the original dimensions of 4.4 meters wide per 2 meters the channel presently shows widths of approximately 250 meters per depths of about 7 meters. Nowadays, about 60% of the freshwater and suspended sediments carried by the Ribeira River, the most important coastal river in São Paulo, reach the lagoonal system, with a consequent modification of environmental conditions (Martinez et al, 2013) and intense siltation (De Mahiques et al, 2014), forming several islands at the mouth of the artificial channel (figures 4 and 5).Furthermore, due to a Pb-mining activity that lasted from 1945 to 1995 in the upstream area of the Ribeira River, the lagoon system received contaminated sediments, with enrichment factors as high as 20 times the natural regional background (de Mahiques et al, 2012) (figure 6). Nowadays, despite the cessation of the mining activities, the system still receives significant quantities of metalenriched sediment since the mining debris are still deposited in the margin of the river (Tramonte et al, 2015).…”