Características Sedimentológicas Da Plataforma Continental Interna Rasa Na Porção Central Do Litoral Paranaense

Abstract

RESUMOO objetivo deste trabalho é caracterizar os sedimentos da plataforma continental interna paranaense entre as profundidades de 5 a 15 m entre os estuários de Guaratuba, ao sul e Paranaguá, ao norte da área de estudo. Informações batimétricas, análises granulométricas e determinação de teores de carbonato e matéria orgânica de amostras de sedimentos de fundo permitiram a geração dos mapas temáticos. Observou-se uma grande predominância de areia fina, porém a média granulométrica dos sedimentos varia do silte grosso até a areia grossa. Foram identificados cinco padrões distintos de sedimentos na área estudada: i) as areias fina e muito fina do delta de maré vazante associado à desembocadura sul do Complexo Estuarino de Paranaguá; ii) as areias muito finas bimodais, com teores de finos entre 10 e 40 %, localizadas próximas à costa, iii) as areias média e grossa unimodais; iv) as areias finas na faixa dos 10 a 15 m de profundidade, unimodais menos selecionadas que as areias finas do delta de maré vazante; v) as areias finas a muito finas das barras do início da zona de arrebentação.Palavras-chave: sedimentos, plataforma interna, Paraná, cerca de energia.

Does the closed fishing season influence the ichthyofauna consumed by Larus dominicanus?

“…In the Superagui Island, Cathorops spixii was the species contributing most to the composition of fish fauna in L. dominicanus diet. This is probably a reflection of the greater abundance and concentration of this species in this area CATTANI et al, 2011), where there is predominance of very fine sediments (silt and clay) at depths less than 10 m (VEIGA et al, 2004), which could favor the concentration of this species in these areas. SCHWARZ et al (2006) states that C. spixii is the most abundant species in the surroundings of Superagui, mainly at 9 m deep, where trawling activities are concentrated.…”

“…On the other hand, in the post-closure, it was possible to observe a greater number of species with individuals of longer lengths. The trawled areas have favorable conditions to sciaenids in terms of turbidity and energy supply, since large part of the bottom substrate has very fine to fine sand (VEIGA et al, 2004), favoring entrapment and the occurrence of organic matter and associated benthic macrofauna. FIGUEIREDO and MENEZES (2000) report the preference of sciaenids for fine sediments; in this way, they respond to the reduction in fishing pressure and return to these areas.…”

Surficial sediments of the Paraná Inner Continental Shelf, Southern Brazil

“…The mean grain size apparently decreases seaward, and the transition zone from very fine sand to mud occurs in approximately 100 m deep (see Figueiredo & Tessler 2004). On larger scale (1:500,000) charts, fine sands are predominant with some occurrences of medium to coarse sand associated with oblique sand ridges, and very fine sand, with mud content between 10 to 40%, related to estuarine supply (Veiga et al 2004(Veiga et al , 2006. Fine sediments also occur at depths of 14 to 16 meters under a 30 cm thick sand layer below the seabed.…”

“…It was partially described in previous large-scale surveys projects such as REMAC (Global Reconnaissance of the Brazilian Continental Margin), and REVIZEE (Living Resources in the Exclusive Economic Zone) and some regional studies carried at the PICS (Veiga et al 2004, Sielski 2015. Despite expected bottom sediments homogeneity observed on small-scale charts (1:1,100,000) (see Milliman & Barreto 1975, Zembruski 1979, Figueiredo & Tessler 2004, the PICS has a complex distribution of sedimentary patches, with the mean diameter of sediments varying from coarse sand to silt (Veiga et al 2004). This contrast could be primarily related to the sample grid size and sampling density, in which higher density or smaller grids produce more detailed information than the opposite.…”

“…This contrast could be primarily related to the sample grid size and sampling density, in which higher density or smaller grids produce more detailed information than the opposite. Furthermore, fine sediments input from large estuaries and palimpsest sediments occurrences may contribute to this sedimentary complexity (Veiga et al 2004).…”