Nematodes vs Macrofauna assemblages along an estuarine gradient (Mondego estuary, Portugal)

Abstract

The spatial distribution of the nematodes and macrofauna communities in the subtidal sediments along estuarine gradient in the Mondego estuary was studied. The main aim is to compare the response of the nematodes and macrofauna communities structure adjusted for each estuarine stretch. Spatial distribution of nematode assemblages followed the estuarine gradients, allowing to distinguish: The freshwater and oligohaline sections, characterised by the presence of freshwater nematodes, low densities and diversity; Mesohaline section, the densities and diversity were also low; Polyhaline and Euhaline sections, attained highest densities and diversity. Significant differences of diversity were obtained between estuarine sections by Shannon-Wiener index. Significant differences in macrofauna densities were also obtained, the highest values were obtained in euhaline and mesohaline areas. The euhaline stations presented higher species richness, while the freshwater section registered lower values. Significant differences of diversity were also obtained between estuarine sections by Shannon-Wiener index. From the management point of view both communities are very useful in assessing ecological quality in transitional waters, however the rapid response of nematodes to environmental changes became an important tool.