Functional ecological patterns and the effect of anthropogenic disturbances on a recently restored Mediterranean coastal lagoon. Needs for a sustainable restoration

We present here a detailed case study on the lessons learned after a restoration process of a natural ecosystem, which can be considered as an ecological experiment. Senillar de Moraira is a brackish water small coastal lagoon located in the Spanish Mediterranean coast. It is separated from the sea by a sand bar and a beach, and is regularly fed by groundwater. Mostly due to the strong anthropogenic pressure this lagoon was degraded, and a restoration process, consisting mostly on the rebuilt of hydro-geomorphological features, was accomplished about a decade ago. After the restoration project, ecological monitoring was performed to reveal the recovery of the ecological integrity of the ecosystem, mainly focusing on the restoration of ecological processes and biological communities. Biological communities, rates of autotrophic (primary production) and heterotrophic (respiration) processes, sediment inputs and wash-out, and other ecological features were monitored during one and half year, two years after the restoration works finished, and the ecological patterns of the current functioning of this ecosystem were determined in order to suggest management strategies for its conservation. The maintenance of most anthropogenic pressures hardly allows the sustainability of natural processes to preserve the ecological health of the ecosystem. According to our results, the success of the restoration process is strongly compromised by the maintenance of most pressures, and subsidies are needed to allow the preservation of a somewhat natural condition of the ecosystem. Though many typical species and functional groups and processes re-established after the restoration, a progressive degradation was observed, especially reflected in the decline of submerged macrophytes that are essential to the maintenance of the ecological health of the system. The decline of these macrophytes was caused by a combination of impacts and risks that were not totally removed when restoration works were accomplished, namely the risk of occasional sewage inputs, increased salinity by groundwater over-exploitation, enhanced siltation caused by deforestation in the catchment, and increased pressure of exotic species. This also resulted in a change of the functioning of the lagoon, from the dominance of autotrophic processes driven by macrophytes, to that of heterotrophic processes mediated by increased organic matter and inorganic nutrient inputs, and to the dominance of phytoplanktonic primary production, as revealed by the statistical analyses of the obtained data. This offers the lesson that attempts for ecological restoration without removing the causes of degradation result in the lack of self-sustainability of ecosystem functioning and drive to a perennial need for maintenance measures. (C) 2012 Elsevier Ltd. All rights reserved.