Benthic nematode assemblage response during the early phase of a natural recovery process of seagrass beds Zostera noltii.

Abstract

Benthic nematodes are widely regarded as very suitable organisms to monitor potential ecological effects of natural and anthropogenic disturbances in aquatic ecosystems. During 2008, the stable seagrass beds of Zostera noltii located in Mira estuary (SW Portugal) disappeared completely. However, during 2009, slight symptoms of natural recovery were observed, a process which has since evolved intermittently. This seagrass beds have a rare database available in Portugal sampled before the disturbance based on temporal and spatial biodiversity patterns nematodes assemblages. The main goal is to investigate the responses of nematode assemblages to Zostera collapse, based on both communities before and during the early natural habitat recovery. We hypothesized that collapse would induce a decrease in abundance and both structural and functional diversity of the nematode assemblages. A PERMANOVA analysis with the 3 factors: “Before” and “After collapse”; 2 sampling “Sites” (A and B); 4 “Sampling Occasions” confirms the existence of significant differences (p<0,05) in abundance and diversity (d, H’), although no significant differences was obtained based on trophic composition and ITD (Index trophic) and MI (Maturity Index). The nematodes community response following this extreme event exhibited considerable resistance and resilience allowing demonstrate a natural adjustment to the new conditions.