DUGi

Relació entre el metabolisme ecosistèmic i l’estat ecològic a les llacunes costaneres del Baix Ter

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@10256@@28654

Mediterranean coastal lagoons are vulnerable ecosystems affected by human and environmental pressures. Despite being legally protected, their ecological status can be altered by disturbances that are difficult to detect using indicators such as nutrient content or species composition-based indices like QAELS e 2010 . This study explores whether certain metabolic indicators of disturbance — gross primary production (GPP), the logarithmic ratio between respiration and production (RP), and its square (RP²) — can serve as a basis for indicators based on functional variables. The study was conducted in five lagoons of the Baix Ter area, with varying degrees of confinement and water renewal. Automatic sensors were used to record environmental data every 10 minutes (such as dissolved oxygen, temperature, or radiation), which were used to calculate metabolic rates. At the same time, samples of aquatic invertebrates were collected to apply the QAELS e 2010 index. The data obtained were analyzed in RStudio using linear and mixed models to assess the relationship between metabolism and ecological status, considering the effects of lagoon identity and seasonality. The results show that RP is the indicator with the strongest statistical correlation to ecological status: high RP values are associated with poorer ecological conditions, especially in open lagoons with high organic loads. In contrast, GPP is more variable and only shows relationships in certain seasons, such as winter. RP² does not correlate with ecological status but may reflect functional imbalances in highly dynamic systems. Confined lagoons, although showing lower GPP and RP values, can maintain good ecological conditions thanks to internal recycling. On the other hand, lagoons with higher water renewal are more vulnerable to external disturbances, showing higher respiration and worse ecological status. In conclusion, lagoon typology and seasonality influence metabolic responses, with GPP being highly variable and RP more stable and associated with degraded ecological status. Although no single metabolic indicator explains all the variability, RP stands out as the most consistent disturbance indicator for a more accurate ecological diagnosis. However, a reliable assessment requires integrating RP with other metabolic indicators and environmental information, thereby improving the evaluation and management of these complex ecosystems

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