Human interventions during the last 70 years have altered the characteristics of the Gialova Lagoon, a coastal wetland that is part of a wider Natura 2000 site. In this study, we explore how human interventions and climate altered the wetland’s hydrological conditions and habitats, leading to changing wetland functions over time. Our interpretations are based on a mixed methodological approach combining conceptual hydrologic models, analysis of aerial photographs, local knowledge, field observations, and GIS (Geographic Information System) analyses. The results show that the combined effects of human interventions and climate have led to increased salinity in the wetland over time. As a result, the fresh and brackish water marshes have gradually been turned into open water or replaced by halophytic vegetation with profound ecological implications. Furthermore, current human activities inside the Natura 2000 area and in the surrounding areas could further impact on the water quantity and quality in the wetland, and on its sensitive ecosystems. We suggest that a more holistic understanding of the broader socio-ecological system is needed to understand the dynamics of the wetland and to achieve sustainable long-term management and conservation strategies.

Olive farming is one of the most important occupations in Messenia, Greece. The region is considered the largest olive producer in the country and it is recognized as a Protected Designation of Origin (PDO) for Kalamata olive oil, which is considered extra fine. In response to the declining trend of organic olive farming in Greece, this study assesses to what extent organic olive farming in Messenia provides a financially and environmentally competitive alternative to conventional olive farming. In this study, 39 olive farmers (23 conventional and 16 organic) participated in interviews based on questionnaires. The results showed that organic olive farming is significantly more profitable than conventional farming, primarily because of a higher price for organic olive oil. Despite this, the majority of the conventional farmers perceived a low profit from organic farming as the main constraint to organic olive farming. All farmers agreed that organic olive farming contributed to a better environment, health and quality of olive oil. Organic farmers used fewer synthetic pesticides and fertilizers and applied more environmentally-friendly ground vegetation management techniques than conventional farmers. Overall, organic farming was found to provide a competitive and sustainable alternative to conventional olive farming in Messenia.

Abstract. Coastal wetlands and lagoons are under pressure due to competing demands for freshwater resources and climatic changes, which may increase salinity and cause a loss of ecological functions. These pressures are particularly high in Mediterranean regions with high evaporative demand compared to precipitation. To manage such wetlands and maximize their provision of ecosystem services, their hydrologic balance must be quantified. However, multiple channels, diffuse surface water exchanges, and diverse groundwater pathways complicate the quantification of different water balance components. To overcome this difficulty, we developed a mass balance approach based on coupled water and salt balance equations to estimate currently unknown water exchange fluxes through the Gialova lagoon, southwestern Peloponnese, Greece. Our approach facilitates quantification of both saline and freshwater exchange fluxes, using measured precipitation, water depth and salinity, and estimated evaporation rates over a study period of 2 years (2016–2017). While water exchanges were dominated by evaporation and saline water inputs from the sea during the summer, precipitation and freshwater inputs were more important during the winter. About 40 % and 60 % of the freshwater inputs were from precipitation and lateral freshwater flows, respectively. Approximately 70 % of the outputs was due to evaporation, with the remaining 30 % being water flow from the lagoon to the sea. Under future drier and warmer conditions, salinity in the lagoon is expected to increase, unless freshwater inputs are enhanced by restoring hydrologic connectivity between the lagoon and the surrounding freshwater bodies. This restoration strategy would be fundamental to stabilizing the current wide seasonal fluctuations in salinity and maintain ecosystem functionality but could be challenging to implement due to expected reductions in water availability in the freshwater bodies supporting the lagoon.

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