DOI: 10.3391/ai.2026.21.3.199579

Authors: Seongjae Kim, Taekjun Lee, Jeounghee Lee

Abstract: The colonial bryozoan Watersipora subtorquata is a globally distributed non-indigenous species (NIS), posing increasing threats to marine biodiversity and coastal industries through biofouling and competition with native biota. In South Korea, despite its recognition as a harmful marine organism, few studies have addressed its ecological behavior under varying environmental conditions. This study investigated the spatiotemporal dynamics of W. subtorquata percent cover in four Korean harbors—Yangpo, Tongyeong, Bieung, and Jeju—over a 39-month period (April 2021 to July 2024). Standardized acrylic settlement plates and in-situ measurements of water temperature and salinity were used to evaluate percent cover patterns. Generalized Additive Models (GAMs) revealed temperature was significantly associated with percent cover across all four harbors, while salinity played a key role in Bieung. A significant interaction effect between temperature and salinity was observed in Jeju. These results provide novel insights into the environmental sensitivity of W. subtorquata, highlighting the importance of multi-regional and long-term monitoring to guide site-specific management of invasive species, while underscoring the need for higher-resolution environmental time series to assess climate-related implications more directly.

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DOI: 10.3391/ai.2025.20.3.162564

Authors: Efim D. Pavlov, Tran Duc Dien, Ekaterina V. Ganzha

Abstract: Non-native suckermouth armoured catfish Pterygoplichthys spp. have spread extensively across many river systems in Vietnam. It is possible that their expanded distribution occurred through the brackish waters of estuaries and coastal zones, facilitating movement from one river system to another. It has been previously hypothesized that, for successful dispersal through brackish water, armoured catfish can tolerate changes in water salinity and are capable of avoiding high salinity levels that threaten their survival. In this study, we experimentally estimated the movements and the directions of juvenile and adult wild loricariids in fresh and brackish water. Our results showed that juveniles exhibit a circadian rhythm of locomotor activity similar to that of adults. However, juveniles display a more pronounced reaction to increasing water salinity ‒ at 5 PSU ‒ while adults respond at 15 PSU. This likely explains the absence of juveniles in natural brackish water environments and their reduced potential to spread through brackish waters compared to adults. Adult loricariids are likely capable of recognizing and avoiding high-salinity zones (>10 PSU) by increasing locomotor activity, predominantly directed toward the surface. Their ability to grasp air helps maintain positive buoyancy, allowing them to remain in the surface layer of freshwater over extended periods of time. Variability in salinity tolerance among adults (ranging from 2 to 16 hours in 15 PSU) may enable some individuals to be more successful in dispersing through estuaries and along coastlines.

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DOI: 10.3391/ai.2025.20.1.151447

Authors: Catherine E. de Rivera, Amy A. Larson, Benjamin G. Rubinoff, Luna R. Soto, Seth L. Wright, Edwin D. Grosholz, Gregory M. Ruiz, Andrew L. Chang

Abstract: The nature and strength of biotic interactions change along stress gradients, but the importance of these interactions across estuarine gradients is under studied. Here, we examined how consumption varies across estuarine salinity gradients by deploying standardized baits (‘squidpops’) to measure consumption pressure along the gradients of five estuaries in Oregon, USA. The relationship between consumption and stress was nonlinear: consumption pressure peaked slightly at mid salinity and decreased at low salinity, especially as temperature increased, in the five estuaries studied. This finding does not support either of two existing models for consumption across gradients, including the Consumer Stress Model and a consumer extension of the Salinity Range Model. The pattern of consumption aligns better with the Prey Stress Model or the Invasion Stress Model, and the latter predicts that successful invasion by stress-tolerant predators extends consumption pressure further upstream along estuarine stress gradients than the Consumer Stress Model. Although these estuaries have been invaded by the crab Carcinus maenas, our catch data did not support the expected greater numbers of these invasive, stress-tolerant predators mid estuary or an expected relationship with native predators, as C. maenas was trapped in low abundance throughout each estuary. While our catch data did not directly support the Invasion Stress Model, we found that individual C. maenas ate more squid in lab experiments when at intermediate salinities than fresher salinities. Overall, our field and lab results suggest consumption peaked at mid estuary, at intermediate to high stress, in these temperate estuaries. The Invasion-Stress Model needs more testing to evaluate whether it, the Prey Stress Model, or a new model is best supported and can predict ecological impacts from changes in precipitation patterns and biological invasions, as well as other environmental stressors for estuarine food webs.

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DOI: 10.3391/ai.2025.20.1.143501

Authors: Jeffrey G. Blumenthal, Andrew L. Chang, Brian S. Cheng, Ellen M. Hines, Leora Nanus, Chela J. Zabin

Abstract: The Atlantic oyster drill Urosalpinx cinerea is an introduced predatory gastropod that has negatively impacted Olympia oyster restoration in multiple estuaries on the west coast of the United States. In San Francisco Bay, California, Atlantic oyster drills have a patchy spatial pattern of presence and absence and occur in a range of densities where they are present. This variable population distribution and a limited understanding of their local dispersal history poses a challenge to oyster restoration site selection. To address this dilemma, we evaluated five abiotic habitat factors as potential determinants of drill distribution. In 2017 and 2018, we compared quarterly drill abundance data to substrate composition, elevation, water temperature, salinity, and inundation at eight sites in Richardson Bay, a small embayment in San Francisco Bay. Using generalized linear mixed effects models, we found that amount of coarse substrate and elevation were positively and negatively, respectively, associated with drill population density at the four sites where drills were present. None of the five habitat factors, however, explained the absence of drills from the other four sites. These findings suggest ways for oyster restoration practitioners to select sites that optimize the chances oyster and drill co-existence or minimize the risk of drill invasion and point to the need for extreme caution against accidental introductions of drills to novel areas with suitable habitat. We recommend extensive drill population surveys in regions where Olympia oyster conservation is taking place coupled with additional fine-scale environmental data to better understand Atlantic oyster drill biogeography and to improve the odds of success of future Olympia oyster restoration work.

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DOI: 10.3391/ai.2024.19.1.115111

Authors: Ningning Chen, Yan Liu, Lin Yuan, Huixian Wu, Junzeng Xue

Abstract: Chthamalus challengeri Hoek, 1883 (Crustacea, Cirripedia) is typically found in the Bohai Sea and Yellow Sea along the coast of China. However, until 2009, it was never seen in the East China Sea. In 2010, C. challengeri was discovered at Yangshan Port in Zhoushan, East China Sea, and it has since been found to invade several islands in the Zhoushan Islands area successfully. Although the population that invaded Yangshan Port has disappeared in recent years, the population that successfully invaded the other islands in Zhoushan has been increasing in density. To study the ecological adaptability of C. challengeri larvae from the Zhoushan Sea Area, we conducted an experiment observing the larvae’s response to different temperatures and salinity gradients. The results indicate that the C. challengeri larvae are highly adaptable to different temperatures and salinities, and under temperatures ranging from 10–25 °C and salinities of 25–35, nauplius can complete all six stages of development and reach a settlement. We found that the survival and settlement rates during larval development were highest at 20 °C and salinity 30, which could be considered the optimum conditions for C. challengeri larvae. At these conditions, it took approximately 11.5 days for the larvae to undergo development from nauplius I to complete settlement. However, lower temperatures slowed down the development rate and settlement of C. challengeri larvae to some extent, while high temperatures can directly lead to the death of C. challengeri. According to the results of this study, the settlement period of C. challengeri in a new habitat can last as long as 7 months (April to November) compared to its original environment. This extended settlement period could provide favorable conditions for the long-distance dispersal of C. challengeri and enhance its invasive ability in new habitats.

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DOI: 10.3391/ai.2023.18.1.103389

Authors: Michele D. Larson, Daniel Greenwood, Kara Flanigan, Amy C. Krist

Abstract: Environmental conditions promoting the occurrence and high abundance of non-native taxa are linked to critical stages of species invasions: establishment, whether a site can sustain a population of the non-native taxon, and impact, the extent to which the consequences of establishment negatively affect the invaded ecosystem. Using surveys across environmental gradients, we examined the physicochemical conditions associated with the occurrence and abundance of the invasive New Zealand mudsnail (Potamopyrgus antipodarum) and co-occurring native mollusks. Abundance of Potamopyrgus very strongly increased with stream width and conductivity (specifically with chloride, sulfate, potassium, and sodium ions). Also, Potamopyrgus were most likely to occur at sites with relatively low pH and water velocity and relatively high calcium ion concentration and abundance also slightly increased in these conditions. The physicochemical conditions indicate the characteristics of sites that are suitable for establishment and secondary spread of Potamopyrgus. Native mollusks differed from Potamopyrgus in the physicochemical conditions associated with abundance suggesting that variation among habitats could permit native mollusks to persist at larger geographic scales even if they often co-occur with Potamopyrgus. Abundance of native Physa moderately decreased with abundance of Potamopyrgus. Because abundance of Physa and Potamopyrgus responded oppositely to stream width and conductivity, the negative relationship between the abundance of these two taxa may be caused by contrasting responses to physicochemical conditions, acting alone or in concert with biotic interactions.

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