Functional traits of polychaetes change between different types of Posidonia oceanica habitats.

Meadows of Posidonia oceanica harbor rich biodiversity and ecosystem functions, yet Biological Traits Analysis on the resident benthic communities are lacking. This study aims to provide insight on the functional diversity of polychaetes communities, a dominant benthic group, between the different habitat types of P. oceanica (plain meadow, strips/patches and dead matte), as well as pilot indicators of habitat modification. The results showed how specific traits relate to the different habitat types. Plain meadow was different to strips/patches and dead matte in functional composition, diversity and thus, the ecosystem functions involved. However, an overlap was observed in functional composition between dead matte and living P. oceanica, due to the remaining matte structure. This highlights the importance of the former on ecosystem functioning and the serious consequences of its current exclusion from conservational legislation. In addition, the classification of species to ecosystem engineering types showed interesting potential as an indicator.

Impacts of dredged-material disposal on the coastal soft-bottom macrofauna, Saronikos Gulf, Greece.

Dredged sediments derived by the low course and estuary of the metropolitan river of Athens (Kifissos River) were dumped every day for 21 months to an open-sea site in the Saronikos Gulf. The spoil-ground and surrounding area was monitored prior, during and post to dumping for 24 months, over 6-month intervals. Dumping significantly changed the granulometry of the pre-existing superficial sediments to finer-grained only in the spoil ground and increased the sediment contamination load (aliphatic, polycyclic aromatic hydrocarbons and heavy metals) throughout the study area. Microtox® SPT showed that sediment toxicity levels were high at almost all sampling stations. During dumping, burial of natural soft-bottom habitats degraded severely the communities of the spoil-ground resulting in an almost azoic state, as well as significantly declined the species number and abundance of benthic communities in locations up to 3.2 km away from the spoil-ground, due to dispersion of the spoil and smothering. Benthic indices on the surrounding sites were significantly correlated with hydrocarbon concentrations and sediment toxicity levels. Post to dumping, the macrofauna communities of the spoil-ground were still significantly degraded, but the surrounding areas showed patterns of recovery. However, the high concentrations of aliphatic, polycyclic aromatic hydrocarbons and levels of toxicity persisted in the sediments after the ceasing of dumping operations in the study area, implying the ecological hazard imposed on the area.