Managing marine biological invasions is challenging due to the complexity of species transfer via ballast water and biofouling, particularly in ports and marinas where NIS can establish and spread. The study by Peters and Meyer (2024) investigated the temporal settlement patterns of marine biofouling communities in False Bay Yacht Club marina, South Africa, using PVC settlement plates. They tracked species composition monthly between April and August 2022 and identified and estimated cover for each species. There was significant monthly variation in species richness and abundance, with NIS comprising 55% of the community and establishing dominance early, with eight of 12 NIS settling within the first month. Key species, including the ascidians Corella eumyota and Diplosoma listerianum, the polychaete Neodexiospira brasiliensis, and the barnacle Balanus trigonus demonstrated strong competitive traits. The study underscores the importance of ongoing, temporally sensitive monitoring to better manage marine bioinvasions and guide biosecurity efforts.

Non-indigenous species (NIS) can disrupt marine ecosystems by altering habitats and reducing native species through rapid growth and resource competition. The bryozoan Amathia verticillata exemplifies this, acting as an ecosystem engineer that provides complex biogenic habitat for diverse marine invertebrates, including native, cryptogenic, and other NIS. In this context, Zavacki et al. (2025) investigated the influence of A. verticillata on marine invertebrate communities in Mission Bay, San Diego, California, USA between July 2021 and 2022. Invertebrate diversity increased with structural complexity, with elongated morphotypes hosting more polychaetes and compact ones harboring more amphipods. Seasonal patterns showed that A. verticillata abundance peaked in warmer months, coinciding with shifts in community composition. The findings suggest that this bryozoan acts as an ecosystem engineer, potentially facilitating the establishment of other NIS and influencing local community dynamics.

Non-indigenous species (NIS) can negatively impact ecosystems by altering food webs and nutrient cycling, as observed with non-indigenous tunicates and mussels affecting aquaculture and primary productivity. Sponges, as filter-feeders, also influence these systems through benthic-pelagic coupling by converting waterborne nutrients into biomass. The population dynamics of NIS sponges is crucial for understanding their ecological impacts. Hoeke et al. (2025) studied the seasonal dynamics of the introduced sponge Hymeniacidon perlevis in Elkhorn Slough, California, USA by tracking its distribution, biomass, and correlations with environmental data between 2007 and 2023. The sponge exhibited a distinct seasonal cycle, with biomass peaking in October (fall) and declining to near absence by March (spring). Warmer temperatures and lower dissolved oxygen were positively correlated with sponge cover, with a time lag of 2–4 months. The population has increased in frequency and density since 2007, particularly in the upper estuary. The study highlights the sponge’s potential ecological impact through water filtration and its adaptability to environmental changes, emphasizing the need for monitoring strategies.

The Mediterranean Sea hosts over 500 NIS, with a high concentration in the eastern basin due to Indo-Pacific introductions via the Suez Canal. Ascidians, particularly NIS, often colonize artificial substrates in harbors, but soft-bottom habitats in the eastern Mediterranean remain understudied even though these habitats are vulnerable to colonization, especially as anthropogenic and natural disturbances alter benthic community dynamics. Framed by this complex scenario, Golanski et al. (2025) documented a novel colonization of the NIS ascidian Microcosmus exasperatus on the sandy bottom of the Israeli Mediterranean coast in September 2022. This species, typically associated with rocky substrates, was observed using polychaete tubes and shells as settlement sites, reaching peak densities of 1.8 individuals per square meter in autumn 2022. The population declined during winter storms and was absent by February 2023 but reappeared in smaller numbers the following summer. The colonization demonstrated the species’ potential for niche expansion into soft-bottom habitats, potentially acting as “stepping stones” for further dispersal. The study highlights the need for long-term monitoring to assess the recurrence and ecological impact of such events.

The introduction of NIS can negatively impact local restoration efforts. Blumenthal et al. (2025) investigated the habitat factors influencing the presence and density of the Atlantic oyster drill, Urosalpinx cinerea, in Richardson Bay (part of San Francisco Bay), California, USA. In this area, there are extensive efforts to restore native Olympia oyster (Ostrea lurida), a prey item of U. cinerea. They found that coarse substrate and elevation were significant predictors of drill density but did not explain the species’ patchy distribution across sites. Historical introduction patterns and limited dispersal ability likely drive distribution, while habitat conditions influence local abundance. The presence of oyster drills poses a challenge for Olympia oyster restoration, necessitating careful site selection and monitoring. The authors recommend more extensive surveys and preventative measures to minimize drill spread and support restoration efforts.

The Great Lakes basin has experienced over many decades a significant rise in NIS, primarily due to ballast water discharge from commercial vessels. While ballast water exchange regulations have reduced new introductions worldwide, unmanaged and untreated ballast water still poses a risk. Environmental DNA (eDNA) monitoring, despite challenges in distinguishing living from non-living organisms, offers a promising tool for early detection and improved NIS management. Sheehan et al. (2024) investigated the persistence of eDNA from the introduced mysid Hemimysis anomala in Great Lakes water to improve NIS monitoring. Using microcosms inoculated with freeze-killed specimens, they measured rapid eDNA decay, with a half-life of 4.5 hours and signal detection ceasing after seven days. The decay followed an exponential pattern, consistent with previous studies on larger organisms, indicating reliable use of qPCR-based eDNA monitoring in ballast water uptake locations. The findings underscore eDNA’s potential as a practical early detection tool for preventing NIS spread via untreated ballast water.

The invasion status of cryptic species is particularly difficult to understand without genetic methods, but species identification is crucial to understand the ecological and management impacts of a species invasion. Kupriyanova et al. (2025) investigated the origins of the polychaete Spirobranchus cf. tetraceros in the Western Mediterranean, previously considered a Lessepsian migrant from the Red Sea. Through genetic analysis (18s rRNA and cyt-b), they identified the species as S. arabicus, originating from the Persian Gulf rather than the Red Sea. The findings challenge the assumption of a natural migration via the Suez Canal, suggesting ship-fouling as the primary introduction vector. The study highlights the complexity of the S. tetraceros species complex and the need for further genetic research to distinguish native from introduced populations. These results underscore the importance of integrative taxonomy for understanding marine bioinvasion pathways.

Climate change is expected to increase the introduction of non-native species in coastal ecosystems, but documenting these changes is challenging due to a shortage of funding for monitoring surveys and lack of taxonomists for specialized groups of organisms. In addition, repeated sampling across locations is crucial for understanding long-term patterns of NIS diversity and abundance. McCann et al. (2025) synthesized a 20-year study on NIS marine bryozoans along both the eastern and western coasts of North America (i.e., the continental United States and Canada), using standardized settlement plate surveys across 35 bays. Additional records were added via literature reviews and rapid assessment survey data. They documented 48 NIS bryozoans, with the Pacific coast hosting the highest diversity, particularly in San Francisco Bay, California. Latitude influenced species richness, with fewer species found at higher latitudes. Hull fouling and ballast water were identified as the primary vectors of introduction, while oyster transplants played a lesser role. The study highlights the importance of ongoing monitoring and the role of shipping activities in the spread of these invasive species.

Biological invasions are a growing environmental concern due to their significant impacts on biodiversity and ecosystem structure, especially when species act as ecosystem engineers by altering habitat complexity. Foundation species, like macroalgae, provide food and shelter for various invertebrates, influencing community dynamics when their composition changes. Human activities such as shipping and aquaculture have facilitated the global spread of these habitat-forming species, leading to significant shifts in marine community structure. Lee et al. (2025) investigated the biogeographic patterns of macroinvertebrate and trematode communities associated with the introduced red alga Gracilaria vermiculophylla along the Atlantic Coast of the United States. Across 17 sites, they found 39 macroinvertebrate taxa, with amphipods dominating the assemblages, and identified the biogeographic region of the recipient community as a key predictor of species richness and abundance. Trematode diversity in the snail host Ilyanassa obsoleta decreased with increasing G. vermiculophylla biomass, though the relationship was not statistically significant. The study revealed distinct community compositions across regions, highlighting the ecological influence of this invasive foundation species. These findings underscore the need for ongoing monitoring to understand long-term ecosystem impacts.

Biotic interactions, particularly predation, vary along environmental stress gradients such as salinity changes in estuaries, where NIS often thrive due to their enhanced stress tolerance. Traditional models like the Consumer Stress Model and Prey Stress Model predict different patterns of predation under stress, but recent research suggests the Invasion Stress Model better explains estuarine dynamics by accounting for invasive species’ influence. Understanding these interactions is essential for predicting community structure changes in invaded estuarine systems. De Rivera et al. (2025) investigated how predator consumption varies along estuarine salinity gradients in five Oregon, USA estuaries. Using standardized bait, they found that consumption peaked at mid-estuary salinities, and declined in fresher waters, especially with higher temperatures. The data did not support existing models like the Consumer Stress Model but aligned with the Prey Stress Model and the Invasion Stress Model. While the introduced green crab Carcinus maenas was present, its abundance did not correlate with consumption patterns, although laboratory experiments showed higher feeding rates at intermediate salinities. The study highlights the need for further research to refine predictive models of predator-prey interactions along estuarine stress gradients.