Efectes d'un incendi sobre el metabolisme de la llacuna del Ter Vell [Fitxer informàtic] / Jaume Archilés Illa ; [dirigit per: Xavier Quintana Pou]
Archilés Illa, Jaume


2023
Dirigida per: Quintana Pou, Xavier. Universitat de Girona. Facultat de Ciències, 2023
1 recurs electrònic
Treball final de grau (Biologia).

In this study, we have described the ecosystem metabolism of Ter Vell, a coastal lagoon located between Torroella de Montgrí and l'Estartit which suffered a wildfire at the end of 2021. We have estimated metabolic rates by applying a Bayesian model to data collected over a period of 9 months. Our objective was to assess the impact of the fire on the metabolism of the lagoon by examining the metabolic rates of production and respiration which are described as good indicators of metabolism in these ecosystems. We also wanted to analyze the seasonal metabolic changes by quantifying the concentration of dissolved oxygen and the ecological state of Ter Vell by comparing the metabolism of the year of the wildfire with that of other previous years. We have observed how during summer months, as light intensity and temperature increase, both production (GPP) and respiration (ER) reach higher values than the rest of the seasons. However, after the fire has occurred, there are also peaks in the GPP. Temperature shows a low and non-significant relationship along production. Comparing GPP with the same rate without the effects of light intensity (GPPmax) we observe that during wildfire it reaches values as high as in summer. GPPmax shows how the wildfire affects the production of the lagoon and therefore its metabolism, although not directly due to the influence of other factors. A similar pattern is also observed in the saturation of dissolved oxygen, which undergoes greater oscillations with higher values during summer months and after the wildfire occurred, reaching the same conclusion. Finally, we compared the PR quotient and GPP with data from 2 previous years, where the meteorological conditions were completely different from those of our study to assessthe ecological state of Ter Vell. PR quotient was identified as the best quality indicator of Ter Vell due to the variations in between the different periods analysed.

Aplicació del model GLM (General Lake Model) per a l'estudi del règim hidrològic de les llacunes litorals de La Pletera [Fitxer informàtic] / Víctor González Torà ; [dirigit per: Xavier Casamitjana]
González Torà, Víctor


2018
Dirigida per: Casamitjana, Xavier. Universitat de Girona. Facultat de Ciències, 2018
1 recurs electrònic
Treball final de grau (Ciències ambientals).

Coastal wetlands are one of the most affected ecosystems by human activity, with a high degradation of their ecological status and, the few remaining are surrounded by buildings. It is one of the richest and most productive ecosystems in the world that maintains a certain balance with the entrances of the sea. The studied area is the Pletera, a wetland system located in the Baix Empordà marsh, close to the mouth of the Ter river, which has recently been de-urbanized thanks to the Life Pletera project, which aims to recover the complete ecological functionality of this zone. Until now, the hypothesis has always been that these loopholes depend only on surface inlets of the sea and precipitation, leaving aside the role of the aquifer. In this work, the hydrological regime and the salinity of three lagoons of La Pletera (Life A, B and C) were analyzed during the period between December 2014 and September 2017. The General Lake Model program, with open source software developed by Hipsey et al., (2014), is a one-dimensional model of equilibrium and stratification of a body of water in line with experimental and meteorological data. Through this program, we have determined for each lagoon, the temporary evolution of the salinity and the underground inflows and outflows, and to elaborate a balance of mass that has allowed to calculate the rates of evaporation and other parameters that affect the lagoons. Moreover, thanks to the meteorological data, the oscillations of the levels of each lagoon have been studied with the sea level and sea storms, among others. The results show that lagoons depend on the underground inputs to maintain their level during the driest and warmest period of the year and its salinity is marked by evaporation, underground inputs and surface sea inlets. In addition, it has been determined that the evaporation of each lagoon depends on its morphology. Based on these results, the present study aims to be another proof of the importance of hydraulic connectivity between the marshes and their underlying aquifers and that requires the commitment of all to preserve it.

Metabolisme ecosistèmic de la llacuna natural Fra Ramon i la restaurada G02 a la Pletera [Fitxer informàtic] / Borja Aramburu Munoa ; [dirigit per: Xavier Quintana Pou]
Aramburu Munoa, Borja


2017
Dirigida per: Quintana Pou, Xavier. Universitat de Girona. Facultat de Ciències, 2017
1 recurs electrònic
Treball final de grau (Ciències ambientals).

The study area is situated in la Pletera, a salt marsh that is located to the north of the mouth of the river Ter (Torroella de Montrí, Girona). The wetlands and lagoons making up the area form part of the Area of Natural Interest. The salt marsh's great ecological interest largely due to the brackish lagoon system present, where the Fra Ramon (FRA) and Bassa Pi (BPI) lagoons are of natural origin and the Pletera Nova (G02) artificial, created on the first LIFE restauration project for the Lower Ter wetlands. The third LIFE project is currently being developed in order to restore the entire lagoon system. Within the framework of this project, a study of the FRA and G02 lagoon ecosystem metabolisms was conducted, whose main objectives were (i) to determine and characterize the Fra Ramon and Pletera Nova lagoon ecosystem metabolisms for a period of 15 months, and to evaluate other research methods previously proposed in various studies on the subject, (ii) to evaluate possible similarities and differences in the metabolic behaviour that lagoons display in relation to one another and towards the temporary seasonal pattern and, (iii) to determine the influence of the water composition on the metabolic functioning of the two lagoons. Throughout the course of the 15-month study, an increase in the production and respiration variables was noted during the summer months. Similarly, it was in the same months that the most days were recorded with a situation of total anoxia in the lagoons, which proved to be related to the wind speed affecting on them. Total production and respiration throughout the entire monitoring period was higher in G02. Nonetheless, FRA displayed more autotrophic behaviour, being the only lagoon that acted as a carbon sink. In the multivariable analysis of the different physicochemical parameters of both lagoons, two main dimensions representing 63.82 [percent] of the explained variance were identified; the first relating to the confinement conditions, and the second to the nutrient input episodes. Only in the second dimension significant differences between lagoons found, and a significant correlation was only noted between the first dimension and the lagoon respiration. The study concluded with a seasonal pattern of the lagoon respiration and production variables in to explain the metabolic functioning throughout the cycle. However, other factors such as nutrients input and the confinement conditions played a secondary role owing to the system features. The behaviour of the younger lagoon suggests a progression in its maturity, and the possibility of the appearance of a perturbation influencing the results is taken into consideration.

Variacions estacionals en la salinitat del subsòl a les basses litorals de nova creació a la Pletera [Fitxer informàtic] / Guillem Ros Roldan ; [dirigit per: David Soler i Hernàndez]
Ros Roldan, Guillem


2017
Dirigida per: Soler i Hernàndez, David. Universitat de Girona. Facultat de Ciències, 2017
1 recurs electrònic
Treball final de grau (Ciències ambientals).

The study area is located within the wetlands of the Baix Empordà, where the old mouth of the River Ter, has led to the formation of a lagoon system that from 1992 is considered an Area of Natural Interest (EIN). The present documented, focuses on the lagoon of Fra Ramon and L04, with the objective of characterizing the seasonal variations in the salinity of the soil. From the data collected seasonally during the period between February 2016 and April 2017, have developed a study of the levels of resistivity electrical resistivity tomography to determine the levels of soil salinity. The ERT (Electrical Resistivity Tomography) has served to create a 2-D model with the distribution of resistivity values in depth, allowing to study the variations of the results among the different campaigns, "Time-lapse", either in [percent] of variation between campaigns, [percent] accumulated or median values of resistivity in depth. These parameters have been related to external data such as the water levels of the lagoons, records of surveys and excavations, and hydro-meteorological and maritime values to determine the temporal variation of salinity and check what are the values that affect in these variations. The resistivity data observed, both by data collected externally and the calculated data in the laboratory, show a clear variation linked on weather conditions depending on the season of the year, having regard to the higher values of salinity in times with the presence of precipitation and an increase in the level of the lagoons and the sea. These conditions would increase the saturation of the material on the top layer of the profile. As has also been observed, there is a relationship between soil moisture and salinity, confirming the reason that soil resistivity increases in time with a high contribution of water in the area, considering the balance between fresh and saline water at each particular time. While in the absence of water and drying of the top layer of the profile would be a decrease in the levels of soil resistivity. On the other band resistivity values in lower layers are related to the intrusion of sea water. With an increase of the effect of the sea water, the levels of resistivity lower and therefore increase the salinity values. On the other band, high resistivity values, will be related to the presence of fresh water.