The Mediterranean Sea, also due to the effects of climate change, is warming at an alarming rate. As a consequence, marine and coastal ecosystems are subjected to a biological change that affects their structure and functioning, with effects also on the fishery trade. One of the main threats is represented by Lessepsian immigration, whose geographic expansion patterns and temporal rates differ among the species. The LEK_1 protocol was applied to collect, from 42 small-scale fishers, information concerning the temporal variations in abundance of overall 18 species in Cyprus and Zakynthos. Species were classified by respondents according to four categories: increasing, decreasing, fluctuant and stable. Data were analysed through the realisation of heatmaps and breakpoints and the study of information related to Maximum-day captures was carried out. The comparison of the two datasets revealed that the considered Lessepsian species arrived and established earlier timewise in Cyprus, where nowadays are present in significantly higher abundances than the ones in Zakynthos. Some species, notably, reached great abundances in Cyprus (above all, L. sceleratus). Instead, the decline of the native S. salpa started prior and reached dramatically lower abundances in Cyprus, even though it has not been subjected to any local extinction. In both the study areas, the variations in the abundances occurred in an impactful short period of time. The income of fishers is influenced by the shifts in species composition and measures on their management, including the enhancement of their commerce, should be improved.
Il mar Mediterraneo, anche a causa degli effetti dovuti ai cambiamenti climatici, sta incrementando la propria temperatura ad un tasso preoccupante. Conseguentemente, gli ecosistemi marini e costieri sono sottoposti ad una variazione biologica che condiziona la loro struttura ed il loro funzionamento. Una delle maggiori minacce è rappresentata dall’immigrazione Lessepsiana, i cui pattern di espansione geografica e di relativa rapidità differiscono tra le specie. Il protocollo LEK_1 è stato applicato per ottenere, da 42 pescatori artigianali, informazioni concernenti le variazioni temporali nell’abbondanza di un totale di 18 specie a Cipro ed a Zante. Le specie sono state classificate dagli intervistati secondo quattro categorie: in aumento, in decremento, fluttuante e stabile. Il confronto dei due dataset ha rivelato che le specie Lessepsiane prese in considerazione sono giunte e si sono stabilite prima a Cipro, dove attualmente sono presenti in abbondanze significativamente maggiori rispetto a quelle di Zante. Alcune specie in particolare hanno raggiunto considerevoli abbondanze a Cipro (più di tutte, L. sceleratus). Al contrario, il declino della specie nativa S. salpa è cominciato prima ed è pervenuto ad abbondanze nettamente inferiori a Cipro, anche se non è avvenuta alcuna estinzione locale. In entrambe le aree di studio le variazioni nelle abbondanze si sono verificate in un periodo di tempo notevolmente breve. Il ricavo dei pescatori è influenzato dal cambiamento nella composizione delle specie e misure sulla gestione delle stesse, inclusa l’agevolazione del loro commercio, dovrebbero essere incrementate.
Specie ittiche non indigene in due isole del Mediterraneo orientale: una ricostruzione storica basata sulla Local Ecological Knowledge
CHIAPPI, MARINA
2021/2022
Abstract
The Mediterranean Sea, also due to the effects of climate change, is warming at an alarming rate. As a consequence, marine and coastal ecosystems are subjected to a biological change that affects their structure and functioning, with effects also on the fishery trade. One of the main threats is represented by Lessepsian immigration, whose geographic expansion patterns and temporal rates differ among the species. The LEK_1 protocol was applied to collect, from 42 small-scale fishers, information concerning the temporal variations in abundance of overall 18 species in Cyprus and Zakynthos. Species were classified by respondents according to four categories: increasing, decreasing, fluctuant and stable. Data were analysed through the realisation of heatmaps and breakpoints and the study of information related to Maximum-day captures was carried out. The comparison of the two datasets revealed that the considered Lessepsian species arrived and established earlier timewise in Cyprus, where nowadays are present in significantly higher abundances than the ones in Zakynthos. Some species, notably, reached great abundances in Cyprus (above all, L. sceleratus). Instead, the decline of the native S. salpa started prior and reached dramatically lower abundances in Cyprus, even though it has not been subjected to any local extinction. In both the study areas, the variations in the abundances occurred in an impactful short period of time. The income of fishers is influenced by the shifts in species composition and measures on their management, including the enhancement of their commerce, should be improved.| File | Dimensione | Formato | |
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Tesi Marina Chiappi.pdf
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https://hdl.handle.net/20.500.12075/9933