Spatio-temporal variation of ecological indicators in the Albufera lagoon of Valencia

The Albufera of Valencia is one of the most iconic wetlands in Europe and represents a paradigmatic example of the difficult but essential interaction between nature and human activity; in fact, it is a symbol of the environmental importance of wetlands, but also of the socio-economic richness that revolves around these areas and of the environmental problems this ecosystem suffers. This thesis was conducted with a research team of the Polytechnic University of Valencia, led by Professor Guillermo Salvador Palau; the object of the research was the study of the rice crops surrounding the Albufera lake in order to better understand the relationships between the human water management of the area and the biodiversity of the wetland ecosystem. A physical-chemical analysis of water was carried out, through the measurement of physical-chemical parameters (dissolved oxygen, oxygen saturation in water, pH, temperature, electrical conductivity, nitrite, nitrate and phosphate concentrations). Following the EU Water Framework Directive200/60/EC, a study of water quality of the area was made, from a physical, chemical and biological point of view. In order to evaluate the biological water quality, the macroinvertebrate community was studied. IMN (Índice de Modo de Nutriciòn) and QAELS (Índex de Qualitat de l’Aigua d’Ecosistemes Lenítics Soms) were used as biological water quality indexes, while Shannon-Wiener and Simpson diversity indexes were used for studying the macroinvertebrates community. Comparisons between areas and over seasons were made, in order to evaluate differences related to water management and ecological indicators. Datasets of 2019 were also compared with datasets from 2018, in order to evaluate differences or analogies and to better understand the effects of the water management. A worst physical-chemical water quality was observed in the northern part of the lagoon, because of the influence of the Pinedo wastewater treatment plant, and this trend was very similar between 2018 and 2019, both in winter and summer. The biological indexes showed a poor quality of the environment, with a low diversity both in northern and southern area of the lagoon. Moreover, the macroinvertebrates class of Ostracoda was analysed: this class, in fact, is considered as a good indicator of water quality: It is sensitive to contamination and alteration phenomena and, particularly, it is a useful bio indicator when studying eutrophication phenomena. This study can help to confirm the reliability of Ostracoda in study eutrophication phenomena but also to find the variables which most influence the abundance of the aforementioned macroinvertebrates and which is the optimal range Ostracoda can live in. Consequently, increasing knowledge about the relationships between environmental features and Ostracoda is therefore essential for the design of effective habitat conservation and wetland restoration actions.