Foraminifera as indicators of marine pollutant contamination on the inner continental shelf of southern Brazil

► The deposition of sand near the estuary's mouth may cause a stagnation problem. ► The increase of sand bank reduces water depth and prevent circulation. ► The accumulation of sand and the absence of fine material lead to a barren zone. ► The Foraminifera fauna has undergone degradation in the central sector. ► Silt and clay's origin comes from both the estuarine system and the sewage outfall.