Benthic meiofauna as indicator of ecological changes in estuarine ecosystems: The use of nematodes in ecological quality assessment

Abstract

a b s t r a c tEstuarine meiofauna communities have been only recently considered to be good indicators of ecological quality, exhibiting several advantages over macrofauna, such as their small size, high abundance, rapid generation times and absence of a planktonic phase. In estuaries we must account not only for a great natural variability along the estuarine gradient (e.g. sediment type and dynamics, oxygen availability, temperature and flow speed) but also for the existence of anthropogenic pressures (e.g. high local population density, presence of harbors and dredging activities).Spatial and temporal biodiversity patterns of meiofauna and free-living marine nematodes were studied in the Mondego estuary (Portugal). Both taxonomic and functional approaches were applied to nematode communities in order to describe the community structure and to relate it with the environmental parameters along the estuary. At all sampling events, nematode assemblages reflected the estuarine gradient, and salinity and grain size composition were confirmed to be the main abiotic factors controlling the distribution of the assemblages.Moreover, the low temporal variability may indicate that natural variability is superimposed by the anthropogenic pressures present in some areas of the estuary. The characterization of both meiofauna and nematode assemblages highlighted the usefulness of the integration of both taxonomic and functional attributes, which must be taken into consideration when assessing the ecological status of estuaries.

Taxonomic resolution and Biological Traits Analysis (BTA) approaches in estuarine free-living nematodes

“…Less obvious was the temporal effect on the distribution pattern of the communities. These findings agree with Alves et al (2013) who gave a detailed account of the genus distribution patterns, diversity and community structure of the nematode communities in the Mondego estuary. A predominance of the spatial effect over the temporal one on the distribution patterns of assemblages was also observed.…”

“…Nematode assemblages have recently been studied along estuarine gradients in Portugal (Adão et al, 2009;Alves et al, 2013). In a previous study by Alves et al (2013), the spatial and temporal biodiversity patterns of free-living nematodes in the Mondego estuary (NE Atlantic coast) were explored.…”

“…Free-living nematodes present several advantages for their use as monitoring organisms (Kennedy and Jacoby, 1999;Schratzberger et al, 2000;Alves et al, 2013). In addition to being highly abundant, they play an important role as intermediaries between the microbial/detrital compartment and larger organisms (Danovaro et al, 2007) and their infaunal lifestyle has a strong influence on the diversity and composition of the assemblage since they are intimately linked with the biogeochemical properties of the sediment (Heip et al, 1985;Steyaert et al, 1999).…”

“…In a previous study by Alves et al (2013), the spatial and temporal biodiversity patterns of free-living nematodes in the Mondego estuary (NE Atlantic coast) were explored. Salinity and grain size composition proved to be important abiotic factors controlling the distribution of these assemblages.…”

A review of Italian research on free-living marine nematodes and the future perspectives on their use as Ecological Indicators (EcoInds)

“…This is also confirmed by investigations carried out in other geographical regions and on different type of disturbances (i.e. Gyedu-Ababio et al, 1999;Armenteros et al, 2010;Alves et al, 2013). Therefore, the taxonomic structure appears to be a promising tool used to assess the EcoQ in line with the WFD.…”