Search Results (6)

Coastal wetlands are critical components of blue carbon ecosystems, yet the functional roles of benthic shellfish species in regulating sediment carbon dynamics are not yet fully elucidated. To address this knowledge gap, we investigated the effects of different shellfish zones—gastropods (Bullacta exarata, Umbonium thomasi) and bivalves (Mactra veneriformis, Meretrix meretrix, Potamocorbula laevis)—on sediment carbon fractions and microbial communities in representative intertidal wetlands of Liaodong Bay, China. We analyzed dissolved organic carbon (DOC), particulate organic carbon (POC), microbial biomass carbon (MBC), enzyme activities, and microbial genomic profiles, with particular emphasis on carbon fixation gene abundance within the top 0–10 cm of sediment. The results showed that POC and MBC levels in gastropod zones were 56.11% and 99.83% higher, respectively, than in bivalve zones, while carbon fixation gene abundance was 14.54% lower. Structural equation modeling (SEM) further revealed that shellfish type had a significant direct effect on MBC (λ = 0.824, p < 0.001). This study provides novel evidence that shellfish community composition regulates blue carbon storage through both biogeochemical and microbial pathways, highlighting the importance of species-specific management in shellfish aquaculture to enhance carbon sequestration. These findings offer a theoretical foundation for future assessments of coastal wetland carbon sinks and ecosystem service valuation. Full article

In order to examine the seasonal variations in the morphological characteristics and diet of Mactra veneriformis in the Northern Yellow River Delta’s intertidal zone and provide a scientific basis for its resource conservation and population restoration, tested clams were collected in four consecutive seasons from summer of 2022 to spring of 2023. Morphological traits were measured, and the DNA of the stomach contents was analyzed using high-throughput sequencing. The tidal differences and seasonal variations in the northern habitat of the Yellow River Estuary significantly affect the morphological characteristics and growth of M. veneriformis. Among the four seasons, significant differences in the morphological characteristics of M. veneriformis were observed between the middle-tide and low-tide zones (p < 0.05). In both middle-tide and low-tide zones, the morphological characteristics and body wet weight of M. veneriformis in winter were significantly higher than those in other seasons (p < 0.05). Moreover, the morphological characteristics of M. veneriformis were extremely significantly influenced by the interaction between tide and season (two-way interaction, p < 0.001). In all seasons, M. veneriformis in the middle- and low-tide zones exhibited positive allometric growth. While there was no significant difference in the stomach content between the spring and summer samples in the same tidal zone (p > 0.05), there was a significant difference between the middle- and low-tide samples in winter (p < 0.05). This suggests that seasonal variations, rather than tidal differences, had a larger impact on the diet of M. veneriformis in the northern Yellow River estuary and that feeding differences may be related to changes in environmental factors, such as temperature. The findings of this study provide initial insights into the feeding ecology of M. veneriformis and offer a scientific foundation for the conservation and management of its resources. Full article

Mactra veneriformis is highly susceptible to ocean acidification (OA) due to its low shell hardness during its rapid growth period. In this study, oxygen consumption rate, ammonia excretion rate, and transcriptome sequencing of mantle tissue analyses were conducted in white and purple shell-color populations of M. veneriformis under OA stress (pH = 7.6). The findings indicated a significant rise in oxygen consumption rates and ammonia excretion rates following acidification in both the two shell colors, while the clams with purple color showed comparatively lower basal metabolic levels. Transcriptomic analyses demonstrated the expression of key genes related to fatty acid synthesis were significantly inhibited, whereas genes involved in calcification, osmoregulation, and immune response were upregulated under OA exposure in the two shell-color groups. However, some genes such as CA and HSP showed a population-specific response between the two shell-color populations. KEGG enrichment analysis revealed that the MAPK signaling pathway and protein processing in the endoplasmic reticulum were significantly enriched in the two acidification groups. This study provides valuable insights into the response of M. veneriformis to OA stress and also helps to predict the future breeding of valuable strains of M. veneriformis. Full article

For the removal of arsenic from marine products, iowaite was prepared and investigated to determine the optimal adsorption process of arsenic. Different chemical forms of arsenic (As(III), As(V)) with varying concentrations (0.15, 1.5, 5, 10, 15, and 20 mg/L) under various conditions including pH (3, 5, 7, 9, 11) and contact time (1, 2, 5, 10, 15, 30, 60, 120, 180 min) were exposed to iowaite. Adsorption isotherms and metal ions kinetic modeling onto the adsorbent were determined based on Langmuir, Freundlich, first- and second-order kinetic models. The adsorption onto iowaite varied depending on the conditions. The adsorption rates of standard solution, As(III) and As(V) exceeded 95% under proper conditions, while high complexity was noted with marine samples. As(III) and As(V) from Mactra veneriformis extraction all decreased when exposed to iowaite. The inclusion morphology and interconversion of organic arsenic limit adsorption. Iowaite can be efficiently used for inorganic arsenic removal from wastewater and different marine food products, which maybe other adsorbent or further performance of iowaite needs to be investigated for organic arsenic. Full article

Recent studies have examined lipophilic marine toxins (LMTs) in shellfish and toxic algae worldwide, but the occurrence and seasonal variations of LMTs in commercial clams (including Mactra veneriformis, Ruditapes philippinarum, Meretrix meretrix, and Cyclina sinensis) at their major culturing area in Jiangsu, China, remain largely unexplored. In this study, a new solid phase extraction (SPE) in combination with an ultra-fast liquid chromatography and triple-quadrupole linear ion trap mass spectrometry (UFLC-TQ-MS) method was developed to determine the presence of 10 typical LMTs (okadaic acid (OA), yessotoxins (YTXs), azaspiracids (AZA1-3), pectenotoxins (PTX2), gymnodimine (GYM), dinophysistoxins (DTX1&2), and spirolides (SPX1)) in the aforementioned four clam matrices. After confirmation of its sensitivity and precision, this method was used to evaluate the amounts of LMTs in clam samples harvested in five aquaculture zones of the Jiangsu coastal area. Monthly variations of GYM, PTX2, OA, and DTX1&2 in 400 clam samples from the sample areas were determined from January 2014 through August 2015. Peak values were observed during May and August. This is the first systematic report of LMTs detected in clam samples harvested in Jiangsu. Follow-up research and the implementation of protective measures are needed to ensure the safety of clams harvested in this area. Full article

Food-derived bioactive compounds are gaining increasing significance in life sciences. In the present study, we identified angiotensin I-converting enzyme (ACE)-inhibitory peptides from Mactra veneriformis hydrolysate using a nano-LC-MS/MS method. Mactra veneriformis hydrolysate was first separated into four fractions (F1–F4) based on molecular weight by ultrafiltration. The fraction with molecular weight lower than 1 kDa (F1) showed the highest ACE inhibitory activity. F1 was then analyzed by a high throughput nano-LC-MS/MS method and sequences of peptides in F1 were calculated accordingly. The 27 peptides identified as above were chemically synthesized and tested for ACE-inhibitory activity. The hexapeptide VVCVPW showed the highest potency with an IC₅₀ value of 4.07 μM. We then investigated the interaction mechanism between the six most potent peptides and ACE by molecular docking. Our docking results suggested that the ACE inhibitory peptides bind to ACE via interactions with His383, His387, and Glu411 residues. Particularly, similar to the thiol group of captopril, the cysteine thiol group of the most potent peptide VVCVPW may play a key role in the binding of this peptide to the ACE active site. Full article