Morfodinâmica de praias estuarinas de baixa energia durante dragagem de aprofundamento do canal da Galheta, Paranaguá – PR

Estuarine beaches are generally classified as low-energy or sheltered due to the predominance of low waves and short periods, which favor the wave approach with large angles due to limited refraction, narrow beachface and narrow or nonexistent berm. The installation of ports in the interior of estuaries causes several negative effects, mainly due to the activities of dredging of navigation channels and secondly, due to the transit of vessels. The objective of the present work was to monitor four estuarine beaches, on the banks of the Paranaguá bay - PR, characterized as low energy beaches, with the purpose of following the short-term morphological and volumetric changes that occurred during a dredging of deepening in the Galheta navigation channel. For this purpose, cross-shore topographic surveys were carried out, before, during and after the dredging, between February 2017 and March 2019, at 10 monitoring sites. Among all the monitored sites, only the easternmost sites on the beaches of Amparo and Maciel show continuous erosion. The causes of this erosion may be related to tide currents associated with low altitudes of the beaches, storm surge events and dredging.

ENVIRONMENTAL DRIVERS OF FISH ASSEMBLAGES FROM THE SHALLOW INFRALITTORAL AREAS OF THE PARANAGUÁ BAY, SOUTHERN BRAZIL

The composition of estuarine fish fauna is dynamic and complex. Despite the variation in fish fauna in estuaries, it is possible to observe some species associated with microhabitats. The assemblage composition of these communities is apparently derived from habitat selection. The aim of this study was to assess the structure of the demersal fish fauna of the Paranaguá Bay and its relationship with biotic and abiotic factors. To this end, monthly collections were conducted using an otter trawl, from October 1999 to September 2000, at five sites in the shallow infralittoral. Biotic (organic matter, and invertebrates) and abiotic factors (salinity, temperature, pH, dissolved oxygen, seston, and nutrients) were recorded during sampling. A total of 6,623 individuals were captured, belonging to 2 species of Chondrichthyes and 53 species of Actinopterygii (26 families). Sciaenidae was the most representative in terms of richness, with 11 species, and Ariidae was the most representative in terms of abundance. The catfish Cathorops spixii was the most abundant species, representing 21 % of the entire catch. There were significant differences in the composition and abundance of the fish fauna among the studied areas, as evidenced by the Shannon-Wiener diversity index. Such differences seem to be related to the complexity of habitats, which occur due to different types of bottom cover found at each sampling site. The abiotic variables indicated little influence on the structure of the fish assembly. These results contribute to a better understanding of the fish fauna from the shallow infralittoral areas of the Paranaguá Bay, and provide data to decision makers for better implementation of management and conservation measures.