Marine environmental research最新文献

Zooplankton are a key food source for fish and shellfish in the Arctic. One of the most valuable areas for fishing potential is the southern Barents Sea. To assess the productive capacity of this coastal area, we examined spatial variations in the summer zooplankton community. We recorded 44 different zooplankton taxa with the most common species being copepods Acartia longiremis, Calanus finmarchicus, Oithona similis, and Temora longicornis. The study revealed two distinct zooplankton groups, one in the fjords and the other in the open sea. These groups were noticeably different because of environmental factors, which aligned closely with the distribution of the zooplankton populations. Smaller neritic (coastal) species made up most of the zooplankton in shallow, inshore waters, while larger Calanus copepods were more common in deeper, offshore waters. Zooplankton biomass and daily production were generally higher in the open sea, reaching averages of 5.4 g (dry mass per m²) and 204 mg (dry mass per m² per day), compared to 0.9 g and 40 mg in inshore waters. The findings showed that water depth, temperature, and chlorophyll a levels were the main environmental factors influencing zooplankton abundance, biomass, and productivity. Zooplankton diversity was higher in the bays, likely due to the more varied environmental conditions found there. Comparative assessment of summer zooplankton biomass and production values underscores the considerable productive potential of the southern Barents Sea. Our findings provide novel insights into the structure and function of Arctic coastal zooplankton communities and offer a valuable baseline for ongoing pelagic ecosystem monitoring.

Intertidal environments are highly dynamic, exposing organisms to multiple physical stressors simultaneously. This study evaluates the physiological responses of encapsulated Acanthina monodon embryos to stressors associated with tidal cycles, using oxidative damage and antioxidant activity as indicators. Egg capsules collected from the rocky intertidal zone were subjected to a tidal cycle including 3 h of emersion followed by re-immersion. Environmental variables such as temperature, humidity, PAR and UV-B radiation were recorded. Samples were analyzed for lipid peroxidation, protein carbonyls, and total antioxidant capacity. Previous studies have shown that initial-stage embryos are particularly vulnerable to desiccation and thermal stress, yet little is known about their antioxidant responses under natural tidal fluctuations. Based on this, we hypothesize that embryos possess a developmentally regulated and environmentally responsive antioxidant defense system envolving an enzymes or non-enzymatic antioxidants that mitigates oxidative damage during emersion and activates repair mechanisms upon re-immersion. Results showed that early-stage embryos exhibited high antioxidant capacity, particularly during air exposure, suggesting an adaptive response to oxidative stress. Prolonged emersion increased oxidative damage markers, while re-immersion reduced them, indicating activation of repair mechanisms. No mortality was observed in any developmental stage. These findings support the hypothesis and highlight antioxidant capacity as a key strategy for survival during early ontogeny in fluctuating intertidal conditions. This study provides insight into the defense mechanisms of A. monodon embryos and their resilience to environmental stress during encapsulated development.

The southwestern continental shelf of the South China Sea (SCS), a vital fishing ground, lacks systematic studies on fish with different feeding habits as bioindicators of heavy metal(loid)s (HMs) pollution. This study combines stable isotope analysis and Monte Carlo simulation (MCS) to assess HMs, trophic dynamics, and human health risks in fish from this region. Results indicate that all HMs concentrations are below safety thresholds set by Chinese and FAO seafood standards. Trophic transfer analysis revealed significant biodilution of Cu, Zn, Cr, Cd, and Ni with increasing δ¹⁵N values, while Mn, As, and Pb showed no significant variation. Mixed feeding fish were significant correlated with Zn, Cd, and Cu; planktivorous species with Cr and Ni; and carnivorous species with Mn and Pb. Health risk assessment revealed significant differences in target hazard quotient (THQ) values for Cr, Zn, Cu, Ni, and Cd among trophic groups, while total THQ (TTHQ) showed no significant variation. Compared to 1D MCS, the two-dimensional MCS (2D MCS) produced lower estimated risks, except for higher carcinogenic risks observed in children. The combined multiple linear regression (MLR) and 2D MCS model estimated the maximum acceptable daily fish intake at 22.4 g/day for children, 93.1 g/day for adult females, and 104.7 g/day for adult males. This study revealed differences in HMs levels and health risks of human consumption among different feeding groups, providing a scientific basis for sustainable fisheries management and safe seafood consumption in the SCS.