Marine and Freshwater Research Marine and Freshwater Research Society
Advances in the aquatic sciences

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Benthic trophic status of aquatic transitional environments with distinct morphological and dynamic characteristics on the South-western Atlantic coast

Ana-Laura Pita , Luis Giménez , Noelia Kandratavicius , Pablo Muniz , Natalia Venturini

Abstract

The benthic trophic status of Uruguayan coastal estuarine habitats (permanently open estuaries and open/closed coastal lagoons) was evaluated, twice in a year and at different spatial scales using the amount and biochemical composition of the sedimentary organic matter. Nested hierarchical ANOVAs were applied to evaluate differences at the habitat level, among sites for each type of estuarine habitat (three estuaries and three lagoons) and between sectors located at different distances from the sea (inner vs outer sectors). Morphological and hydrodynamic differences between the two types of habitats explained site-to-site variations in eutrophic conditions in the open/closed coastal lagoons and meso-oligotrophic conditions in permanently open estuaries. These differences followed the patterns found for sediment grain size, with inner sectors (lower energy areas), favouring the accumulation of finer sediments and higher amounts of degraded/detrital organic matter. In autumn, biochemical parameters indicated, the dominance of aged and more degraded organic matter, with low nutritional value in both types of habitats, no matter the sector considered. By contrast in spring, biochemical composition showed the prevalence of fresh and more labile sedimentary organic matter with high food value, especially in the outer sectors.

MF16284  Accepted 01 March 2017

© CSIRO 2017