The Influence of Mud on the Inner Shelf, Shoreface, Beach, and Surf Zone Morphodynamics — Cassino, Southern Brazil

Phytoplankton Interannual Variability at Cassino Beach, Southern Brazil (1992–2007), with Emphasis on the Surf Zone Diatom Asterionellopsis glacialis

“…The reduced frequency of A. glacialis accumulations in the surf zone after 1998 was certainly related with this phenomenon since the suspension and onshore transport of large amount of mud probably removed and/or buried the A. glacialis benthic stocks from the backshore. In fact, Calliari et al (2007) showed that the mud deposition at the beach and shoreface acts as a sediment sink, which can also be applied to the diatoms.…”

“…Waves of~4.7 m in height and periods of 14 s suspended and transported the thick layer (up to 1.2 m) of fluid mud (1,230 kg m −3 ) located in the backshore (6-15-m isobaths) to the beach, forming mud banks in the surf zone, which were exposed at the shoreline (Calliari et al 2000(Calliari et al , 2007. The high viscosity of water and the strong energy dissipation rate caused the attenuation of surface waves with damping effect as far as 6 km offshore, resulting in completely altered surf zone dynamics for 14 months, when another cold front passage in April 1999 removed the fluid mud from shoreface (Calliari et al 2000(Calliari et al , 2007. The reduced frequency of A. glacialis accumulations in the surf zone after 1998 was certainly related with this phenomenon since the suspension and onshore transport of large amount of mud probably removed and/or buried the A. glacialis benthic stocks from the backshore.…”

“…It was shown that an unusual episode of mud deposition in the shoreface, surf zone, and foreshore of Cassino Beach in the year 1998, which persisted several months and coincided with an El Niño phase and high precipitation in southern Brazil, significantly reduced the abundance of A. glacialis for the following couple of years . Mud deposition episodes are recurrent phenomena at Cassino Beach and are associated with the discharge of large amount of suspended matter from the Patos Lagoon, forming muddy sediments along~50 km on the shoreface, though the 1998 event was of extreme magnitude (Calliari et al 2007). The main goal of our study is to evaluate possible long-term variation in the phytoplankton community of Cassino Beach by reevaluating previous data (1994( -2000 and analyzing a longer time frame of continuous monthly samples (16 years, 1992-2007).…”

Urban activity and mercury contamination in estuarine and marine sediments (Southern Brazil)

“…This can be explained by a disproportionate volume of sediments being resuspended during dredging and sedimentary load being naturally deposited from the plume in the coastal zone. According to Calliari et al (2007), during the last 20 years, approximately 30 × 10 6 m 3 of sediment have been dredged (an annual average of 1.5 × 10 6 m 3 ), and about 64 × 10 6 m 3 deposited naturally(an annual average of 3.2 × 10 6 m 3 ). If we assume that even up to 5% of the total dredge volume (1.5 × 10 3 m 3 )is suspended in estuarine water, this amount is a small part (1/40) of the total volume of mud input in the coastal area by natural influence in the last 20 years.…”

Surficial sediments of the Paraná Inner Continental Shelf, Southern Brazil

“…The inner continental shelf of the South of Rio Grande do Sul, is one example of the capacity of waves to mobilize fine-grained sediments. These sediments supplied by Patos Lagoon to the inner continental shelf can reach the beach after storm events (Calliari et al 2007). Despite the similarities of both Paraná and south of Rio Grande do Sul inner continental shelves, such as the wave regime and the gentle slope, there is no report of mud reaching the beaches on the Paraná coast.…”