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  • Low-cost citizen science effectively monitors the rapid expansion of a marine invasive species
    Publication . Encarnação, João; Baptista, Vânia; Teodosio, Maria; Morais, Pedro
    Citizen science and informed citizens have become fundamental in providing the first records and accounts about the expansion of numerous non-indigenous species. However, implementing a successful citizen science campaign can be expensive and particularly difficult for aquatic species. Here, we demonstrate how a low-cost citizen science campaign and its outreach plan in social and traditional media enabled to track the expansion of the Atlantic blue crab Callinectes sapidus Rathbun, 1896 along the coast of Algarve (southern Portugal, Europe). We describe the outreach strategy and a cost-benefit analysis of the first year of the citizen science campaign. Social media platforms allowed us to reach a significant number of citizens (over 31,500 clicks in Facebook publications), while traditional media gave national visibility to the citizen science campaign and biological invasions. In only 1 year, we documented the spread of the invasive Atlantic blue crab across the entire 140 km of the Algarve coast with 166 valid observations referring to 1747 specimens, submitted by 62 citizen scientists. We spent 0 € on the citizen science campaign, but considering the time invested in the campaign the cost would have summed up to 3,751 €, while the total minimum cost for one scientist to go to the field and retrieve the equivalent information would have exceeded 11,000 €. We used free online tools of communication to obtain the records about the Atlantic blue crab, instead of a dedicated web platform or mobile app, and handled social media accounts ourselves, which saved us at least 18,815 €. The citizen science campaign revealed that the Atlantic blue crab is unequivocally established in southern Portugal and that females appear to exhibit summer migrations to coastal areas to spawn as in the native area. Overall, our lowcost citizen science campaign effectively documented the rapid spread of a marine invasive species while providing some insights into its ecology. Our strategy can be easily replicated and implemented elsewhere in the world to tackle the ever-growing problem of biological invasions while increasing the scientific literacy of local populations.
  • Invasive fish keeps native feeding strategy despite high niche overlap with a congener species
    Publication . Cerveira, Inês; Dias, Ester; Baptista, Vânia; Teodosio, Maria; Morais, Pedro
    Weakfish Cynoscion regalis (Bloch and Schneider, 1801) is one of the most recent invasive fish in the Iberian Peninsula (Europe). Weakfish has established in the Sado estuary (Portugal) since the early 2010s, and fishers and anglers have expressed concern about its impacts on native prize fish. However, almost a decade later, there is no information on the ecology of weakfish in the non-native area. So, we aimed to assess weakfish feeding strategy and feeding plasticity through stomach content analysis to evaluate if these factors may contribute to its invasiveness, as well as to determine the ecological overlap between weakfish and three native prize fish - European bass, white seabream, and particularly meagre (since they are taxonomically closer), through carbon and nitrogen stable isotopes. Our results demonstrate that Sado's weakfish has a generalist feeding strategy and preys the same functional groups it targets in the native area, therefore feeding strategy may weigh on invasiveness but not feeding plasticity. Weakfish, meagre, and European bass were in the same trophic level and weakfish exhibited higher trophic overlap with meagre, suggesting that weakfish could directly impact meagre if food and habitat become limiting. This study is the first assessment about weakfish ecology in the non-native area and our findings are an excellent starting point to understand this invasion. It can also be useful for management programmes that promote weakfish consumption to minimize its impacts, alleviate fishing pressure on native species, and raise public awareness.