Environmental Assessment of saltmarshes at Patos Lagoon Estuary - RS

Abstract

Saltmarshes in Patos Lagoon Estuary have been converted since XIX century due to urban, port and industrial expansion, however in the last 53 years losses of saltmarshes were caused mainly by natural process (erosion). Biological and ecological processes in saltmarshes have been modified by anthropogenic activities, so this study aimed to identify and quantify the anthropogenic (grazing, fire, harvesting, litter, embankments, and man-made channels) and natural disturbances (erosion) on saltmarshes. Anthropogenic disturbances and erosion were quantified in intensity and spatial extension, evaluated through random transects. Saltmarshes showed some types of disturbance (anthropogenic and/or erosion) with low intensity and moderate extension (10-50 m). There are 23 saltmarsh units at Patos Lagoon Estuary, and it was possible to detect 4 main groups of units under different disturbances, caused by farming and ranching (11 unit-grazing), urban activities (5 unit-litter), fire (4 units), and erosion (3 units). Saltmarsh plants have showed good resilience by fast recovering (3 years) after anthropogenic disturbances (grazing, fire, litter and harvesting).