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Enhancing Seed Harvest of Wild Manila Clam (Ruditapes philippinarum) through Fiberglass Mesh Installation in the Tidal Flat of Jugyo, West Coast of Korea
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.
Journal Article
500-year-old clams!
Poor old Ming was a very old clam indeed! This book introduces young audiences to the fascinating story of Ming the Quahog clam, whose story is a lesson in life cycles, ecology, climate change, environmentalism, responsible science, and much more. The best part is, all of these complex science concepts are made easy for young readers. By communicating this tale of marine science with accessible language and vivid, full-color photography, readers are sure to be bitten by the science bug, and inspired to learn more.
Book
Negative effects of Corbicula fluminea over native freshwater mussels
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.
Journal Article
Stubby the fearless squid
Stubby, a timid squid, and Razor Clam become pen pals, exchanging fanciful tales of their courageous acts, but when they meet, Stubby's brave imaginings are put to the test.
Book
Effects of Three Microalgal Diets Varying in LC-PUFA Composition on Growth, IFad/I, and IElovl/I Expressions, and Fatty Acid Profiles in Juvenile Razor Clam ISinonovacula constricta/I
The razor clam Sinonovacula constricta is the first marine mollusk demonstrated to possess the complete long-chain polyunsaturated fatty acids (LC-PUFA) biosynthetic pathway. This study explored the impact of different microalgae on growth, Fad and Elovl expressions, and fatty acid (FA) profiles in juvenile S. constricta. Results revealed that juveniles fed with Isochrysis galbana (rich in DHA) or Chaetoceros calcitrans (rich in EPA) consistently exhibited higher growth than those fed Chlorella sp. (rich in LA and ALA), underscoring the importance of dietary LC-PUFA in S. constricta’s development. Expression of most Fad and Elovl in C. calcitrans and I. galbana-fed juveniles were initially up-regulated, then down-regulated, suggesting LC-PUFA demand for faster growth. Although Chlorella sp.-fed juveniles exhibited decreased mRNA levels for most genes, levels were notably higher lately compared to those fed C. calcitrans or I. galbana, hinting at potential LC-PUFA biosynthesis induction. FA profiles in S. constricta generally mirrored those in ingested microalgae, implying direct FA accumulation from diets. Some microalgal FA were absent in farmed S. constricta, while others emerged, indicating S. constricta’s ability to selectively accumulate and synthesize FA. This study enhances the understanding of dietary FA metabolism in S. constricta, valuable for selecting appropriate microalgae in its farming practices.
Journal Article
Off the conservation radar: the hidden story of Europe's tiny pea clams (Bivalvia: Sphaeriidae)
This study highlights the conservation problems faced by the tiny freshwater bivalves of the family Sphaeriidae, also known as pea, pill, or fingernail clams (or mussels) in Europe. Despite their global distribution, assumed ecological importance, and potential uses, basic knowledge about their taxonomy, biology, and ecology is very limited and much lower than for the larger freshwater bivalve taxa. Immediate scientific priorities are required to fill knowledge gaps regarding their taxonomy, genetic diversity, distribution, reproductive cycle, ecosystem functions, and population trends. Such fundamental knowledge is necessary to identify specific threats and develop appropriate conservation actions. Deploying environmental DNA analysis at a large scale could be a valuable way to fill gaps in distribution and strengthen monitoring in areas where local taxonomic knowledge is lacking. Until taxon-specific management plans can be developed, we recommend that efforts concentrate on the general protection and restoration of wetland habitats, implementing pollution control measures, and managing invasive species. These actions should be complemented by community engagement through citizen science initiatives. Additionally, prioritising data collection to fill existing knowledge gaps and updating conservation statuses (Red Lists) based on comprehensive assessments will be crucial. Implementing these actions will provide a starting point for the broader protection of freshwater ecosystems, thus benefiting pea clams and other interconnected species within these habitats.
Journal Article
High stream flows dilute environmental DNA (eDNA) concentrations and reduce detectability
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.
Journal Article
Interactive effects of acidification, hypoxia, and thermal stress on growth, respiration, and survival of four North Atlantic bivalves
We investigated the individual and interactive effects of coastal and climate change stressors (elevated temperatures, acidification, and hypoxia) on the growth, survival, and respiration rates of 4 commercially and ecologically important North Atlantic bivalves: bay scallops Argopecten irradians, Eastern oysters Crassostrea virginica, blue mussels Mytilus edulis, and hard clams Mercenaria mercenaria. Month-long experiments were performed on multiple cohorts of post-set juveniles using conditions commonly found during summer months within eutrophied, shallow, temperate, coastal environments (24–31°C; 2–7 mg O₂ l−1; pHT, total scale, 7.2–8.0). Elevated temperatures most consistently altered the performance of the bivalves, with both positive and negative physiological consequences. Low levels of dissolved oxygen (DO) and pH individually reduced the survival, shell growth, and/or tissue weight of each bivalve, with A. irradians being the most vulnerable species. Low DO also significantly increased respiration rates of A. irradians and M. mercenaria, evidencing a compensatory physiological response to hypoxia. M. edulis and M. mercenaria both displayed size-dependent vulnerability to acidification, with smaller individuals being more susceptible. The combination of low DO and low pH often interacted antagonistically to yield growth rates higher than would be predicted from either individual stressor, potentially suggesting that some anaerobic metabolic pathways may function optimally under hypercapnia. Elevated temperature and low pH interacted both antagonistically and synergistically, producing outcomes that could not be predicted from the responses to individual stressors. Collectively, this study revealed species- and size-specific vulnerabilities of bivalves to coastal stressors along with unpredicted interactions among those stressors.
Journal Article
Ecotoxicity of Copper
Copper (Cu) is a ubiquitous trace element in the aquatic environment, and is usually found at low levels. Copper environmental concentrations can be altered as a result anthropogenic activities. Shellfish are useful bioindicators to ensure adequate environmental monitoring. Thus, the aim of the present study was as follows: (a) determine the LC[sub.50] of copper(I) chloride in grooved carpet shell (Ruditapes decussatus) collected in the Santa Gilla lagoon (Sardinia, Italy), and (b) analyze the antioxidant biomarkers in digestive gland and gills of same specimens exposed to different concentrations of the above-mentioned metal (0.045, 0.45, and 0.90 mg/L) for 96 h. A withdrawal period of 96 h was considered for the treated clam, carrying out the same biochemical analyses, superoxide dismutase (SOD), catalase (CAT), selenium-dependent glutathione peroxidase (Se-GPx), glutathione S-transferases (GSTs), and total glutathione (GSH+2GSSG) in the two tissues. Different time and dose responses of the antioxidant biomarkers were recorded in the digestive glands and gills. Oxidative stress biomarkers highlighted the ability of Cu to induce oxidative stress in R. decussatus. Clam, following the withdrawal period of 96 h, has not been able to achieve the control levels of all biochemical markers in the digestive gland and gills. R. decussatus can be a suitable model to assess the ecotoxicity of copper in aquatic ecosystems. These findings may advance knowledge on the role and the effects of copper on oxidative stress biomarkers in grooved carpet shell. The metal ecotoxicity response can be useful to perform accurate biomarker-based monitoring programs using this bivalve species.
Journal Article