Water resources management and ecological response in the Albufera lagoon of Valencia

Natural resources in wetlands are always been exploited for human activities. The Albufera of Valencia is a freshwater lagoon and estuary on the Valencian coast in eastern Spain. This lagoon is an anthropic system due to the fact that his natural regime has been affected by the consequences of the urban and industrial development. Rice fields surrounding the Albufera lagoon form a system of wetlands which provide habitat for the survival of aquatic vegetation and macroinvertebrates, which constitute the main food source for fish and birds. This research, conducted with the help of a research group of the Polytechnic University of Valencia leaded by Prof. Guillermo Palau Salvador, has explored the relationship between wetland communities and anthropogenic disturbances with the purpose to demonstrate that a correct water management can help to make possible a sustainable development of the area and a conservation of the ecosystem. The Albufera lagoon and the surrounding wetlands receive water for irrigation from various sources, including as major contributors two rivers, Jucar and Turia, and, during summer, the waste water treatment plant of Pinedo. Due to the complexity of the system and the different water sources, an assessment of the ecological response of the Albufera lagoon and wetland is currently needed. To evaluate possible differences in terms of diversity and abundance of macroinvertebrates, four different sampling areas have been selected in this study according to the origins of water. One in the north that receive water from the WWTP of Pinedo, one in the south supplied by the river Jucar and two other irrigation areas directly supplied by the lagoon, namely North Tancats and South Tancats. Moreover, two sampling periods in 2018 have been selected according to the flooding cycles: the winter period during which wetlands are flooded for bird breeding and nesting and the summer period, during which agricultural areas are flooded for the rice cultivation. In general, flooded area is much bigger in summer than in winter, with average values respectively of 170 km2 and 90 km2. To evaluate the ecological response of the Albufera lagoon and wetlands macroinvertebrate community has been used as an indicator and in parallel some physical-chemical, chemical and microbiological parameters have been measured. Shannon, Simpson, QAELS, IMN, IBMWP are the biotic indices that have been used, since they are complementary to each other and provide information on the water quality from different perspectives. As we expected from such an anthropic territory, the average of biotic indices shows a moderate pollution level and a low water quality in all areas. Furthermore, the Shannon diversity index (SDI) has been employed to compare the four selected areas and to extrapolate local results to the entire Albufera system. Differences between sampling areas and periods have been observed: North areas show a SDI average value of 1,2 in winter and 1,8 in summer; South areas a SDI average value of 1,5 in winter and 2 in summer. In general, indices values are higher in summer than in winter. Through SDI can be concluded that waste water treatment plant in the north is causing major ecological problems, whereas the water coming from Jucar river seems to be of higher quality. Further studies and a more extended sampling are needed to better describe the spatial and temporal variation of the ecological response in the entire Albufera system.