Invasion genomics uncover contrasting scenarios of genetic diversity in a widespread marine invader

Invasion rates have increased in the past 100 y irrespective of international conventions. What characterizes a successful invasion event? And how does genetic diversity translate into invasion success? Employing a whole-genome perspective using one of the most successful marine invasive species world-wide as a model, we resolve temporal invasion dynamics during independent invasion events in Eurasia. We reveal complex regionally independent invasion histories including cases of recurrent translocations, time-limited translocations, and stepping-stone range expansions with severe bottlenecks within the same species. Irrespective of these different invasion dynamics, which lead to contrasting patterns of genetic diversity, all nonindigenous populations are similarly successful. This illustrates that genetic diversity, per se, is not necessarily the driving force behind invasion success. Other factors such as propagule pressure and repeated introductions are an important contribution to facilitate successful invasions. This calls into question the dominant paradigm of the genetic paradox of invasions, i.e., the successful establishment of nonindigenous populations with low levels of genetic diversity.

Low-Cost Citizen Science Effectively Monitors the Rapid Expansion of a Marine Invasive Species

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 low-cost 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.

Environmental DNA sampling protocols for the surveillance of marine non-indigenous species v3

This document describes a series of protocols for the collection of environmental samples intended for the monitoring and surveillance of marine invasive species by means of eDNA metabarcoding analysis, as described in the associated publication (Fernandez et al. 2021: https://doi.org/10.1016/j.marpolbul.2021.112893).

Environmental sample collection for eDNA analysis v1

This document describes a series of protocols for the collection of environmental samples intended for the monitoring and surveillance of marine invasive species by means of eDNA metabarcoding analysis, as described in the associated publication (Fernandez et al. 2021: https://doi.org/10.1016/j.marpolbul.2021.112893).

Combating marine invasive alien species effectively in Australia

Marine invasive alien species are sea-based organisms that are non-native to a marine ecosystem, and which can or have spread to a degree that has an adverse impact on biodiversity and human livelihoods. In a globalized and inter-connected world, the threats posed by marine invasive alien species are here to stay. Accordingly, it often has been lamented that the threats from marine alien species are too difficult to combat effectively. In Australia, these threats are exacerbated by the country's unique characteristics such as its sheer size, as well as its geographical and historical isolation from the rest of the world. More importantly for the purposes of this article, Australia's unique constitutional framework that entrenches its national system of federalism has led to complex power-sharing arrangements between the Commonwealth, and the State and Territory governments in the management of invasive alien species, which are arguably inadequate to combat marine invasive alien species effectively. In Australia, laws have been made to manage only one vector of marine invasive species, ballast water from vessels, but not for other vectors. This article analyses how marine invasive alien species are currently managed within the Australian legal framework, and discusses what can be done to improve the status quo in order effectively to control the spread of such foreign organisms. It argues with optimism that marine invasive alien species can be effectively managed under a strong legal framework that seeks to prevent their occurrence and minimize the negative impacts of their occurrence. Such a legal framework consists of sound domestic laws and institutions, the effects of which can be enhanced by greater international cooperation.

Citizens’ Eyes on Mnemiopsis: How to Multiply Sightings with a Click!

Monitoring the spreading of marine invasive species represents one of the most relevant challenges for marine scientists in order to understand their impact on the environment. In recent years, citizen science is becoming more and more involved in research programs, especially taking advantage of new digital technologies. Here, we present the results obtained in the first 20 months (from 12 July 2019 to 8 March 2021) since launching avvistAPP. This new app was conceived to track the spreading of the invasive ctenophore Mnemiopsis leidyi in the Adriatic Sea; it was also designed to collect sightings of 18 additional marine taxa (ctenophores, jellyfish, sea turtles, dolphins, salps and noble pen shell). A total of 1224 sightings were recorded, of which 530 referred to Mnemiopsis, followed by the scyphozoan jellyfish Rhizostoma pulmo (22%), Cotylorhiza tuberculata (11%) and Aurelia spp. (8%). avvistAPP produced data confirming the presence of Mnemiopsis (often in abundances > 20 individuals m−2) along almost the entire Italian coast in the summer of 2019 and 2020.