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Lee, H.-J.; Jeung, H.-D.; Song, J.-H.; Hur, Y.B., and Hong, H.-K., 2024. Enhancing seed harvest of wild Manila clam (Ruditapes philippinarum) through fiberglass mesh installation in the tidal flat of Jugyo, west coast of Korea. Journal of Coastal Research, 40(3), 613–616. Charlotte (North Carolina), ISSN 0749-0208. The Manila clam, Ruditapes philippinarum (Bivalvia: Veneridae), is a commercially important species cultivated in tidal flats along the coasts of Korea. However, the local clam industries on the west coast face challenges due to a shortage of seed clams, primarily relying on catching wild juveniles or importing seeds from China. This study aimed to enhance the natural seed harvest of Manila clams by installing fiberglass mesh on the tidal flats of Jugyo, Korea. Fiberglass mesh was installed at three different stations on the tidal flats in October 2017 and clam density was monitored monthly from November 2017 to January 2018. Sediment samples were collected at each station three times using stainless steel quad-rats, and clams were categorized by size (<5 mm, 5–10 mm, 10–20 mm, 20–30 mm, and >30 mm). The results revealed spatial and temporal variations in clam density, with higher concentrations observed closer to the tidal waterline. Clam size distribution also differed across stations, with smaller clams dominating certain areas. The mesh installation in November 2017 did not significantly affect clam density compared with the control group. However, clam density substantially increased in December 2017 and January 2018 because of mesh installation, especially at the lowest station. These findings suggest that installing fiberglass mesh can enhance the survival of newly settled Manila clams, providing a potential solution to the seed shortage the local clam industries face.

The global decline of freshwater mussels is related with a great variety of factors, including the introduction of invasive species. However, the possible effects of other invasive bivalves, such as the Asian clam Corbicula fluminea (Müller, 1774), remain mainly unknown and highly speculative with very few manipulative experiments addressing this issue. In this study, field and laboratory experiments were conducted to assess the possible negative effects of C. fluminea on the native freshwater mussel Unio delphinus Spengler, 1783. Growth, physiological condition, and the locomotor activity were assessed in U. delphinus at increasing C. fluminea density. U. delphinus exhibited lower growth, lower physiological condition, and higher locomotor activity at higher C. fluminea density, which may suggest that this unionid is negatively affected by C. fluminea and may be displaced to less favorable habitats. Although we were not able to establish the main mechanism(s) responsible for these results, possibilities include competition for food resources, competition for space which may result in mussel displacements and/or changes in microhabitat features as a result of bioturbation activities, and production of feces and pseudofeces by C. fluminea.

Aim Environmental DNA (eDNA) is a rapidly emerging methodology with important applications to environmental management and conservation. However, the effects of stream flow or discharge on eDNA have been minimally investigated in lotic (stream and river) environments. In this study, we examined the role of stream flow on eDNA concentrations and detectability of an invasive clam (Corbicula fluminea), while also accounting for other abiotic and biotic variables. Location Illinois, United States of America. Methods We used a longitudinal study over a year in two streams, as well as a seasonal study (summer, autumn) in eight streams, to investigate the effects of variable stream flow on eDNA concentrations and detectability. We used linear mixed‐effects models to assess the influence of various factors on eDNA concentration and occupancy models to make predictions on how seasonality can influence eDNA detection. Results We found higher stream flows decreased eDNA concentrations, and floods produced false negatives or non‐detections at locations where C. fluminea was relatively common. In addition, we found concentrations and detectability of C. fluminea eDNA to be higher in summer than in autumn. Main conclusions We found that stream flow dilutes eDNA concentrations, which may have serious implications for the detection of low abundance organisms. Managers and practitioners applying eDNA for rare species should seek to sample at low or base stream flows when feasible, and future studies should investigate whether our findings here are consistent for other taxa and lotic ecosystems.

The objective of this study is to provide an updated account of the distribution history of two invasive molluscs, Corbicula fluminea and Dreissena polymorpha, both in Europe and worldwide. In addition to this, the study also intends to review their ecological requirements to gain a better understanding of their invasive potential and distribution dynamics. Specifically, the study focuses on updating the distribution and ecological characteristics of these freshwater bivalves in the lower sector of the Danube River and the lakes of the Danube Delta. The purpose is to better understand their invasive and distribution dynamics and to develop effective measures to limit their spread in the future. To achieve this, environmental proxies such as sediment particle size and Total Organic Carbon (TOC) concentrations were used to assess their tolerances. However, the results did not show a significant correlation between the densities of these bivalves and the analyzed environmental parameters. Despite this, the species were found in high densities and formed well-developed benthic communities in some stations. The study contributes to the understanding of the invasiveness of these bivalve species and their distribution range dynamics. Nonetheless, further investigation is required to fully comprehend the role of environmental parameters in their distribution. The study covers the period between 2010 and 2020 and focuses on the lower Danube River sector and Danube Delta.

Despite the full attention of malacologists to the study of Corbicula clams, stimulated mainly due to their high invasive potential and unique breeding system, studies based on an integrative taxonomic approach to identify various invasive lineages of this genus in European Russia are still limited. Our fieldwork was conducted in the Don, Volga, and Caspian Sea basins. In total, four distinct morphotypes belonging to the European forms R, Rlc, S, and “Int” of Corbicula clams were distinguished. According to our molecular genetic data, two Corbicula lineages, relevant to the nominal species Corbicula fluminea and C. fluminalis, can be defined. We observed a discrepancy between mtDNA haplotypes and morphological features for all individuals that were sampled from the Don and Kura Rivers. Identified mismatch may be due to the androgenetic reproduction of Corbicula that leads to cytonuclear inconsistencies. The 28S rRNA polymorphism in C. fluminea and C. fluminalis from studied localities was recorded. This occurrence is perhaps due to hybridization events between forms R, S, and Rlc. The biogeographic origins of Corbicula invasive lineages are discussed. Corbicula fluminalis (FW17, form S) has been detected for first time in the native range, namely in Azerbaijan, Tajikistan, Turkey, and Myanmar. We assume that the invasion of C. fluminalis into reservoirs and watercourses of the Caspian Sea basin (Republic of Dagestan and Stavropol Krai of Russia) was from Western Asia and Transcaucasia, and the introduction of C. fluminea to the Don and Volga River basins was from unspecified European countries.

We present an interdisciplinary review of the observed and projected variations in atmospheric and oceanic circulation within the southwestern South Atlantic focused on basin-scale processes driven by climate change, and their potential impact on the regional fisheries. The observed patterns of atmospheric circulation anomalies are consistent with anthropogenic climate change. There is strong scientific evidence suggesting that the Brazil Current is intensifying and shifting southwards during the past decades in response to changes in near-surface wind patterns, leading to intense ocean warming along the path of the Brazil Current, the South Brazil Bight, and in the Río de la Plata. These changes are presumably responsible for the poleward shift of commercially important pelagic species in the region and the long-term shift from cold-water to warm-water species in industrial fisheries of Uruguay. Scientific and traditional knowledge shows that climate change is also affecting small-scale fisheries. Long-term records suggest that mass mortalities decimated harvested clam populations along coastal ecosystems of the region, leading to prolonged shellfishery closures. More frequent and intense harmful algal blooms together with unfavorable environmental conditions driven by climate change stressors affect coastal shellfisheries, impact economic revenues, and damage the livelihood of local communities. We identify future modelling needs to reduce uncertainty in the expected effects of climate change on marine fisheries. However, the paucity of fisheries data prevents a more effective assessment of the impact of climate change on fisheries and hampers the ability of governments and communities to adapt to these changes.

This study investigates the network of causal relationships in the king’s littleneck clam (Ameghinomya antiqua) fishery in the southern zone of the Los Lagos Region, Chile, using the Convergent Cross Mapping (CCM) method. The dynamics of the system were analysed based on four time series: abundance indices derived from landings per unit effort (LPUE), the percentage of mega-spawners (Mega) in catches, landings and sea surface temperature (SST) anomalies. The study identified a significant unidirectional causal relationship between landings and landings per unit, and between sea surface temperature and catch per unit effort. A marginally significant one-way causal relationship between landing and mega-spawners was found. A unidirectional causal relationship was also observed from temperature to landings; the extended CCM suggested that landings respond with a lag of 2-4 months to changes on SST. Landings and LPUE were driven by the shared environmental force (sea surface temperature). The results suggested that controlling landings rates can influence management decisions aimed at regulating resource conservation, using a precautionary approach and a target reference value for LPUE. The importance of incorporating indicators such as mega-spawners into management strategies is highlighted, as they can be indicators of the stock’s health status. This study improves the comprehension of how environmental and socio-economic factor interact in complex system.

This study was conducted within the project River2Ocean—Socio-ecological and biotechnological solutions for the conservation and valorisation of aquatic biodiversity in the Minho Region, with the reference NORTE-01-0145-FEDER-000068, co-financed by the European Regional Development Fund (ERDF), through Programa Operacional Regional do Norte (NORTE 2020). This study was also supported by national funds through FCT—Foundation for Science and Technology within the scope of UIDB/04423/2020 and UIDP/04423/2020 and by the COST Action CA18239, supported by COST (European Cooperation in Science and Technology). VM was supported by doctoral grant SFRH/BD/108298/2015 from the Portuguese Foundation for Science and Technology—FCT through POPH/FSE funds. AML was supported by the Institute of Environmental Sciences, Jagiellonian University (bailout no. N18/DBS/000003). NF-R was supported by a postdoctoral fellowship from the government of the autonomous community of Galicia (Xunta de Galicia, ED481D-2021-023). NEC graciously acknowledges support from the Irish Research Council (GOIPD/2022/861).

Among UV-filters, benzophenones are one of the most abundantly used and detected groups in the environment. Bisphenols are also one of the most widely used chemicals in plastics, but their demonstrated deleterious effects on several organisms and humans have led to the production of alternative analogues. However, few comparative studies on the ecotoxicological effects of these derivatives or analogues have been carried out. The present study aimed to investigate the effects of two benzophenones (BP-3 and BP-4) and two bisphenols (BPA and BPS) in a short-term exposure of the freshwater endobenthic bivalve Corbicula fluminea. Clams were exposed for 96 h to several concentrations of the four pollutants: BP-3 (0.63; 1.25; 2.5; 5 mg l−1), BP-4 (4.75; 9.5; 19; 38 mg l−1), BPA (3.75; 7.5; 15; 30 mg l−1), and BPS (2.5; 5; 10; 20 mg l−1). The comparative acute toxicity of these pollutants was evaluated by the analysis of the post-exposure filtering capacity of clams, lipid peroxidation (LP) levels and the activity of the antioxidant enzymes catalase (CAT) and glutathione reductase (GR). After the exposure period, except for BP-4, the chemicals tested seemed to be detected by clams and provoked valve closure, decreasing filter-feeding in a concentration-dependent manner. Furthermore, C. fluminea exposed to the highest concentrations of BP-3, BP-4 and BPA showed a significant increase in LP, CAT and GR activities with respect to their controls. BP-3 and BPA were the most toxic compounds showing significant differences in all the parameters analysed at the highest concentrations assayed. However, clams exposed to BPS showed only significant alterations in filtration parameters and in GR activity, in the two highest concentrations tested, indicating that this compound was the least toxic to clams. Obtained results highlight the importance of investigating the effects that emerging pollutants have on aquatic organisms.