Multiple stressors affect coastal marine ecosystems, whose effects are often largely unknown. This represents a crucial point, since the knowledge about the impacts caused by human activities are essential to apply adequate monitoring plans and mitigation strategy. Consequently, in this thesis four different human pressures were selected and investigated, in order to increase the available information. The first impact source selected is represented by desalination plants, for which the impact on macrobenthic assemblage was investigated. The results suggest that they do not cause alterations superimposed to the natural spatial variability of the macrofauna assemblage. This has been related to the small sizes of the plants. Similar results were obtained for the second stressor investigated (i.e., beach nourishment and beach re-profiling), which did not alter the spatial-temporal trend of the macro-meiofauna assemblage. Again, the lack of a significant impact was associated to the small size of the interventions. The third case study investigated the long term (40 years) changes (in m2) of seagrass meadow extension in the North Adriatic Sea. The results indicated that the two declines recorded were mainly correlated with two different drivers: urbanization and positive thermal anomalies respectively, which affected not only the meadow extension but also the species composition. Finally, the last pressure analyzed is the fishing with hydraulic dredging, which is extremely intensive in the Adriatic Sea. Specifically, here the effects of the decrease of fishing effort (of about 50%) imposed by the SARS-CoV-2 sanitary emergency was studied. From the results, it is evident a significant increase of bivalves, making the entire macrofauna assemblage significantly different from that present before the 2020. Overall, from these case studies, it is clear as a crucial role is played by the “size” of the human pressure. In addition, it is clear that in different ecosystems, when there is a noticeably decrease of human pressures, an appreciable partial recovery is possible.
Gli ecosistemi marini sono sottoposti a diversi fattori di stress di origine antropica, i cui effetti non sono ancora del tutto noti. Questo gap conoscitivo rappresenta un punto cruciale, in quanto, la conoscenza degli effetti delle attività umane è essenziale per l’applicazione di piani di monitoraggio e di adeguate strategie di mitigazione. Di conseguenza, in questa tesi, sono stati selezionati e studiati quattro diversi tipi di pressioni antropiche; allo scopo di aumentare le conoscenze disponibili come richiesto dalla MSFD. La prima fonte di impatto selezionata sono gli impianti di desalinizzazione, per i quali è stato studiato l’impatto sulla comunità macrobentonica. I risultati ottenuti suggeriscono che non sono causa di alterazioni distinguibili dalla naturale variabilità spaziale della macrofauna. Ciò può essere messo in relazione alle piccole dimensioni degli impianti. Risultati simili sono stati ottenuti per la seconda pressione antropica studiata, cioè ripascimento e (ri)stenditura della sabbia sugli arenili, i quali, non hanno alterato la naturale variazione spaziale e temporale della macro e meiofauna. Anche in questo caso, la mancanza di un impatto significativo è da attribuire alla piccola scala dell’intervento. Il terzo caso di studio riguardava l’analisi dell’estensione (m2) di una prateria di fanerogame nell’arco di 40 anni. I risultati indicano, come i due declini riscontrati fossero correlati a due diversi fattori, quali urbanizzazione e aumento della temperatura, i quali hanno agito non solo sull’estensione della prateria, ma anche sulla composizione tassonomica. Infine, è stato analizzato il potenziale impatto della pesca con draghe idrauliche, particolarmente intensa nel Mare Adriatico. Più specificatamente, è stato studiato il potenziale effetto della diminuzione dello sforzo di pesca (di circa il 50%) imposto dall’emergenza sanitaria del SARS-CoV-2 sulle comunità macrobentoniche. I risultati evidenziano un aumento significativo dei bivalvi, che porta ad una comunità macrobentonica significativamente diversa rispetto a quella presente prima del lockdown. In conclusione, dall’analisi questi casi di studio è emerso come la “scala” della pressione antropica giochi un ruolo cruciale nel determinare l’eventuale impatto. Inoltre, è stato evidenziato come diversi ecosistemi mostrino una apprezzabile resilienza quando le pressioni antropiche diminuiscono in maniera significativa.
Multiple stressors affect coastal marine ecosystems / Nepote, Ettore. - (2022 Mar 14).
Multiple stressors affect coastal marine ecosystems
NEPOTE, ETTORE
2022-03-14
Abstract
Multiple stressors affect coastal marine ecosystems, whose effects are often largely unknown. This represents a crucial point, since the knowledge about the impacts caused by human activities are essential to apply adequate monitoring plans and mitigation strategy. Consequently, in this thesis four different human pressures were selected and investigated, in order to increase the available information. The first impact source selected is represented by desalination plants, for which the impact on macrobenthic assemblage was investigated. The results suggest that they do not cause alterations superimposed to the natural spatial variability of the macrofauna assemblage. This has been related to the small sizes of the plants. Similar results were obtained for the second stressor investigated (i.e., beach nourishment and beach re-profiling), which did not alter the spatial-temporal trend of the macro-meiofauna assemblage. Again, the lack of a significant impact was associated to the small size of the interventions. The third case study investigated the long term (40 years) changes (in m2) of seagrass meadow extension in the North Adriatic Sea. The results indicated that the two declines recorded were mainly correlated with two different drivers: urbanization and positive thermal anomalies respectively, which affected not only the meadow extension but also the species composition. Finally, the last pressure analyzed is the fishing with hydraulic dredging, which is extremely intensive in the Adriatic Sea. Specifically, here the effects of the decrease of fishing effort (of about 50%) imposed by the SARS-CoV-2 sanitary emergency was studied. From the results, it is evident a significant increase of bivalves, making the entire macrofauna assemblage significantly different from that present before the 2020. Overall, from these case studies, it is clear as a crucial role is played by the “size” of the human pressure. In addition, it is clear that in different ecosystems, when there is a noticeably decrease of human pressures, an appreciable partial recovery is possible.File | Dimensione | Formato | |
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