FREE-LIVING MARINE NEMATODES COMMUNITY STRUCTURAL CHANGES WITHIN A POST-DREDGING SITE AT THE ROMANIAN SHELF

摘要

The paper presents the results of assessment of nematodes community diversity and quantitative structure within an area heavily affected by dredging activities performed in the summer 2016 in a perimeter of 2.7 km2, at depths between 23-27 m within the circalittoral habitats of the Romanian shelf. The nematodes composition changes after almost three years since the dredging cessation were investigated within the direct impacted area where the physical disturbance of sediments is still clearly detectible and in a reference site. Our results show that the recolonisation process of the impacted area is still ongoing, a lower diversity being noted in the centre than at the fringes of the investigated perimeters. In terms of abundance, the community distribution did not exhibit a clear pattern, a trending biased by substrate type and macrofauna influence being assumed. The attempt of evaluating the ecological quality using Bongers Maturity Index (MI) based on changes underwent by nematodes community reflected the physical disturbance of habitats in general, allowing us to assess the meiobenthic population resilience after such events. In addition, the MI showed a good evidence of the organic pollution and contamination.