Marine environmental research最新文献

Phosphorus (P) is an essential nutrient driving algal growth in aquatic ecosystems. Dissolved inorganic and organic P (DIP and DOP) are the main components in the marine P pools and are closely related to harmful algal blooms. The dinoflagellate Akashiwo sanguinea is a cosmopolitan species which frequently causes dense blooms in estuaries and coasts worldwide, while the availability of P to A. sanguinea still remain unclear. Herein, the physiological and transcriptomic responses of A. sanguinea grown under P-deficient, DIP-replete and DOP-replete conditions were compared. P-deficient adversely suppressed the growth and photosynthesis of A. sanguinea, while genes associated with P transport, DOP utilization, sulfolipid synthesis, and energy production, were markedly elevated. Three forms of DOP, namely, glucose-6-phosphate (G-6-P), adenosine 5-triphosphate (ATP), and β-Glycerol phosphate (SG-P), supported A. sanguinea growth as efficiently as DIP (NaH₂PO₄), and no significant difference was observed in biochemical compositions and photosynthesis of A. sanguinea between the DIP and DOP treatments. While the genes related to P transporter were markedly suppressed in DOP groups compared with the DIP group. Our results indicated that A. sanguinea is a good growth strategist under P-deficient/replete conditions, and this species had evolved a comprehensive strategy to cope with P deficiency, which might be a crucial factor driving bloom formation in a low inorganic P environment.

Marine pollutants, especially potentially toxic elements (PTEs), increasingly threaten the ecological environment and fishery resources of the Beibu Gulf due to their bioaccumulative nature, toxicity, and persistence. However, the occurrences of multiple PTEs in marine invertebrates within this region remains unclear. Hence, a total of 18 species of commercially harvested invertebrates (shrimp, crab, cephalopod, shellfish, and sea cucumber) were collected from the Beibu Gulf, and the concentrations of nine important PTEs (As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn) were examined. Subsequent stable isotope analysis for δ¹³C and δ¹⁵N facilitated investigations into biomagnification and human health risk assessment. The results showed that, except for As, the concentrations of the PTEs in the invertebrates were below the national safety limits. Furthermore, significant positive correlations were found between trophic levels (TLs) and log-transformed concentrations of As (P < 0.001, R² = 0.20) and Cr (P < 0.001, R² = 0.13), indicating biomagnification of these two metals across trophic positions among species. Finally, the human health risk assessment revealed that the consumption of cephalopod, shellfish, and sea cucumber poses a higher risk of adverse effects compared to shrimp and crab.

Global warming may affect the health of marine species. However, the collected information on quantitative assessment of response in fish under elevated temperature is poorly defined. The present study aimed to quantitatively evaluate the effects of the hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂) under elevated temperature (33 °C and 36 °C, ET1 and ET2) stress for 14 days. As endpoints, we examined changes in body growth, hemato-immunological parameters, liver oxidative stress markers, as well as changes of the stomach digestive enzymes. Compared to the control, the body weight was significantly decreased in ET2 group for 14 d exposure, and a remarkable change of differential leukocyte counts of the fish was observed in ET1 group at 3 d and in ET2 group at 14 d. The respiratory burst activity of the hybrid grouper leukocytes markedly decreased in the treatment groups after 14-d exposure. Overall, the antioxidant enzyme activities and transcriptional levels of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and glutathione peroxidase (GSH-PX) were markedly inhibited in the liver for 3-d and 14-d exposure. The expression levels of nf-κb mRNA were significantly inhibited while the expression levels of atp2b1 mRNA were significantly induced after 14-d exposure. The activities of pepsin and lipase in the stomach were significantly reduced. In addition, an innovative hazard classification system (ET-HCS) was developed to quantitatively characterize the stress response of the fish following elevated temperature treatments. The stress level of ET2 group for 14-d exposure was ranked as level IV (high stress), and the other treatments were ranked as level II (low stress). Taken together, the findings of this study further extend our understanding of quantitative assessment of response in fish under high-temperature stress, which provides valuable information for improving countermeasures of mariculture industry.

This study assessed the levels of Cd, Cu and Pb in the sentinel bivalve Donax trunculus collected from two touristic Moroccan sandy beaches, namely Agadir and Taghazout, in Morocco. The results revealed higher metal contamination in D. trunculus specimens collected from Taghazout compared to those from Agadir. Among the metals analyzed, Pb was found to pose the greatest risk to human health, followed by Cd and Cu. The study also investigated the presence of the trematode parasite Bacciger bacciger in D. trunculus specimens. The parasite was found only in female D. trunculus from Taghazout, with infection rates ranging from 11% to 46%. Furthermore, significantly higher levels of oxidative stress biomarkers were observed in specimens from Taghazout, where positive correlations were observed between Cu, Cd, Glutathione S-Transferase, and parasite prevalence, as well as between Pb and Catalase. In the case of D. trunculus collected from Agadir, Malondialdehyde levels were positively correlated with Cd and negatively correlated with Pb, while Catalase levels were negatively correlated with Cu. Complex interactions emerged between metal pollution, parasitic infection, and oxidative stress biomarkers in D. trunculus from two Moroccan coastal sites. Evaluating biotic stress synergies with biomarkers shows promise for integrating biological implications of coastal contamination.

Microplastics (MP) are omnipresent in aquaculture and can induce several toxic effects, mainly oxidative stress. Therefore, alternatives to minimize these effects are welcome. In this study, chitosan (1 and 3 g/kg) was supplemented through the feed of farmed shrimp P. vannamei for 30 days. After this period, the shrimp were exposed to MP (0.5 mg/L) for 7 days. The results showed the presence of MP in hepatopancreas, gills and muscle. Hepatopancreas morphological alterations, as well as lipid peroxidation, a decrease in GSH level, and an increase in SOD activity indicated an oxidative stress that was reversed by chitosan. The muscle was also affected by MP, showing decreased CAT activity and increased SOD activity, though no lipid peroxidation was observed. In muscle, chitosan reversed the SOD increase to basal activity. The results obtained showed that chitosan was more effective against oxidative stress than in preventing accumulation and histological damage.