ALBERT

Description: 1. Ballast water has been identified as a leading vector for introduction of non-indigenous species (NIS). Recently, the International Maritime Organization (IMO) implemented management standards – D-2 – where all large, commercial ships trading internationally are required to adopt an approved treatment system using technologies such as ultraviolet radiation or chlorination. However, current management regulations are based only on the total abundance of viable taxa transported (i.e., total propagule pressure), largely ignoring species richness (i.e., colonization pressure). 2. To determine the efficacy of chlorine treatment in reducing invasion risks and changes in transported biological communities inside ballast tanks, we used DNA metabarcoding-based approaches to estimate colonization pressure (here, the number of species/Operational Taxonomic Units (OTUs) introduced) and relative propagule pressure (relative abundance of each species/OTU) of zooplankton communities in control and chlorine treated tanks during four transatlantic voyages. 3. Our study demonstrated that transport itself did not significantly reduce colonization pressure of zooplankton species, nor did chlorine treatment. Chlorine treatment altered community structure by reducing relative propagule pressure of some taxa such as Mollusca and Rotifera, while increasing relative propagule pressure of some Oligohymenophorea and Copepoda species. 4. Synthesis and applications. Chlorine treatment may not reduce invasion risks as much as previously thought. Reduction in total propagule pressure does not mean reduction in abundance of all species equally. While some taxa might experience drastically reduced abundance, others might not change at all or increase due to hatching from dormant stages initiated by chlorine exposure. Therefore, management strategies should consider changes in total propagule pressure and colonization pressure when forecasting risk of new invasions. We therefore recommend adopting new approaches, such as DNA metabarcoding-based methods, to assess the whole biodiversity discharged from ballast water. As species responses to chlorine treatment are variable and affected by concentration, we also recommend a combination of different technologies to reduce introduction risks of aquatic organisms.

Description: Biological invasion provides a promising system for studying rapid environmental accommodation and adaptation in the wild. Mounting evidence indicates that epigenetic modifications such as DNA methylation play crucial roles in rapid local accommodation and adaptation. Thus, we hypothesize that different local environments can trigger methylation divergence among marine invasive populations at fine geographical scales. In this study, we examined population methylation patterns in the invasive ascidian, Ciona intestinalis, along the Atlantic coast of Nova Scotia, Canada, where significant temperature differences exist at defined locations along the coast. Using the methylation-sensitive amplification polymorphism (MSAP) technique, we observed a high level of intra- and inter-population diversity, as well as significant population methylation differentiation. We identified a correlation between local environments and methylation patterns, and further consistently recovered 14 temperature-related subepiloci by using multiple analyses. All these results demonstrate a substantial role of temperature in shaping population methylation patterns and an epigenetic response to environmental changes during range expansions. The complex fine-scale methylation structures among populations of C. intestinalis observed in this study suggest that multiple biotic and abiotic factors, as well as their interactions, should be further investigated to reveal epigenetic mechanisms of local accommodation and adaptation during biological invasions in marine ecosystems.

Description: Invasions of freshwater habitats by marine and brackish species have become more frequent in recent years with many of those species originating from the Ponto-Caspian region. Populations of Ponto-Caspian species have successfully established in the North and Baltic Seas and their adjoining rivers, as well as in the Great Lakes-St. Lawrence River region. To determine if Ponto-Caspian taxa more readily acclimatize to and colonize diverse salinity habitats than taxa from other regions, we conducted laboratory experiments on 22 populations of eight gammarid species native to the Ponto-Caspian, Northern European and Great Lakes-St. Lawrence River regions. In addition, we conducted a literature search to survey salinity ranges of these species worldwide. Finally, to explore evolutionary relationships among examined species and their populations, we sequenced the mitochondrial cytochrome c oxidase subunit I gene (COI) from individuals used for our experiments. Our study revealed that all tested populations tolerate wide ranges of salinity, however, different patterns arose among species from different regions. Ponto-Caspian taxa showed lower mortality in fresh water, while Northern European taxa showed lower mortality in fully marine conditions. Genetic analyses showed evolutionary divergence among species from different regions. Due to the geological history of the two regions, as well as high tolerance of Ponto-Caspian species to fresh water whereas Northern European species are more tolerant of fully marine conditions, we suggest that species originating from the Ponto-Caspian and Northern European regions may be adapted to freshwater and marine environments, respectively. Consequently, the perception that Ponto-Caspian species are more successful colonizers might be biased by the fact that areas with highest introduction frequency of NIS (i.e., shipping ports) are environmentally variable habitats which often include freshwater conditions that cannot be tolerated by euryhaline taxa of marine origin.

Description: A comprehensive dataset of non-native species (NNS) was assembled by combining the SInAS database of alien species occurrences (Seebens, 2021) with several other publicly available databases and NNS lists to examine NNS diversity globally (Bailey et al., 2020; Campbell et al., 2016; Carlton & Eldredge, 2009; Casties et al., 2016; Eldredge & Carlton, 2015; Hewitt et al., 2002, 2004; Lambert, 2002; Meyer, 2000; NEMESIS, 2017, 2020; Paulay et al., 2002; Richardson et al., 2020; Schwindt et al., 2020; Sturtevant et al., 2019; U.S. Geological Survey, 2017; Wonham & Carlton, 2005) to examine NNS diversity globally. The SInAS_AlienSpeciesDB_2.4.1 file was used as the base file for our dataset. Species without assignment of invaded country/region were removed from the dataset. Then, species assigned only as CASUAL and ABSENT in the columns degreeOfEstablishment (N) and occurrenceStatus (L), respectively, were also removed due to their undetermined non-native establishment status in those particular regions (Groom et al., 2019). Following, species from other publicly available databases and NNS lists that had not been listed for particular region/s in the SInAS database were added to the file. The species that were both native and NNS within a continent were retained in the dataset. Accordingly, the dataset consisted 36 822 species established outside of their native regions, out of which 36 326 came from Seebens (2021) and 496 species from other databases and NNS lists. Binominal scientific names, phylum, class, and family levels were assigned to each species based on the SInAS_AlienSpeciesDB_2.4.1_FullTaxaList file that was originally determined following Global Biodiversity Information Facility (GBIF). When a species was not automatically assigned to binominal scientific name and/or taxonomic level, an additional manual search of GBIF, World Register of Marine Species (WoRMS) and a general internet search engine was conducted in June and July 2022, and September 2023. Also, to examine NNS diversity among different habitats (i.e., terrestrial, freshwater, and marine), we assigned one or more habitats for each species based on the Step2_StandardTerms_GRIIS file; habitat data in the Step2_StandardTerms_GRIIS file originated from the Global Register of Introduced and Invasive Species (GRIIS). Again, if habitat(s) was(were) not automatically assigned to a species, an additional manual search of WoRMS and a general internet search engine was conducted from July to September 2022. We emphasize that due to the great number of species in our dataset and changing information availability over time, there is a possibility that we did not list all potential habitats for all species. Brackish habitats were defined as marine based on the Venice System (1958). Regions were assigned based on the geographic continental definitions (i.e., North America, South America, Europe, Africa, Asia, and Australia), with Pacific islands as a separate region due to their unclear/undefined continental affiliations (National Geographic Society, 2022). Finally, global estimated biodiversity (i.e., numbers of species per taxonomic group) of each particular phylum, class, and family was obtained from the GBIF in October 2022 (GBIF, 2022).

Description: Although anthropogenic activities are widely recognized as a major threat to marine biodiversity, their impacts have not been fully assessed and there is an urge to improve the understanding of the magnitude and mechanisms of those impacts. In this study, we used DNA metabarcoding-based methods to investigate plankton biodiversity patterns under varying anthropogenic pressures (i.e., shipping and bivalve aquaculture) along the eastern Adriatic coast. Our study determined similar community structures among investigated coastal locations in three geographic regions in the Adriatic Sea, as well as between shipping ports and aquaculture sites.