Trophodynamics and potential health risk assessment of heavy metals in the mangrove food web in Yanpu Bay, China

Eco-resilience of China's mangrove wetlands: The impact of heavy metal pollution and dynamics

Mangrove forests in China have significantly degraded over the past several decades primarily due to rapid economic growth and land reclamation for aquaculture and infrastructure development. Among various threats, heavy metal pollution, primarily from urbanization, agricultural runoff, and industrial runoff, poses a substantial risk to mangroves in China. It impairs their ecological functions, limiting biodiversity and reducing their natural ability to sequester carbon and detoxify coastal areas. Despite these challenges, the mangrove ecosystem's resilience in China has not been completely compromised. Natural adaptations and phytoremediation mechanisms, such as limiting metal uptake, excreting metal binding proteins, upregulating antioxidants, forming Fe plague, excreting metals through salt glands, and tolerance to specific metal concentrations, help mitigate heavy metal toxicity. However, these adaptive strategies are limited by the extent of pollutants and the speed at which these pollution factors arise. This review highlights a need to shift restoration efforts from expanding mangrove areas to enhancing ecosystem integrity, with a specific focus on reducing heavy metal pollution through phytoremediation. It also examines how heavy metal interactions at the sediment-water interface impact microbial communities and local fauna, contributing to climate change. Addressing these challenges is critical to improving mangrove conservation in China and ensuring the long-term health and resilience of these critical ecosystems for future generations.

Marine food web trophic interaction of trace elements and stable isotopes of carbon and nitrogen in Rabigh lagoon, Red Sea, Saudi Arabia

The increase in heavy metal pollution in mangrove ecosystems due to anthropogenic activities has been on the increase and has been studied previously. However, there is a need for a better understanding of the use of stable isotopes of carbon (δ13C) and nitrogen (δ15N) to establish trophic levels (TL) and their contamination in the food web. In this study, samples of sediment, mangrove, algae, seagrasses, crustacean, poriferans, echinoderms, molluscs, cnidarian and fishes were collected for determination of trace elements (Fe, Mn, Cu, Zn, Cd, Cr, Pb, Ni and Co) and stable isotopes. Varian 720-ES inductively coupled plasma-optical emission spectrometer (ICP-OES) and Thermo elementary analyser-ConFlo IV-Delta V Advantage mass spectrometer were used for the analysis of metals and stable isotopes respectively. The food web structure of Rabigh lagoon mangrove comprises a group of organisms such as crustacean (crab), porifera (sponges), echinoderm (starfish), mollusc (aquatic snails) and cnidarian (coral) in the second trophic level (TL = 1.0-2.0). For the third trophic level (TL = 2-3), Platycephalus bassensis (TL = 2.96) and Scomber sp. (TL = 2.30) belonging to the taxonomic group fishes are the two organisms in this trophic level. However, from the 9 trace elements determined, only Cd and Pb recorded excessive bioconcentration in the species. In terms of Total Magnification Factor (TMF) and metal concentrations, there was significant biodilution of all trace elements determined in this study except for Pb (TMF = 0.72; p > 0.05) and Co across the extracted food web consisting of molluscs, crustacean and fishes. Biodilution of Pb was not significant across the trophic levels of the food web. This study provides baseline information on the food web structure and transfer of trace elements across the food web of Rabigh mangrove, Red Sea, Saudi Arabia.

Mercury trophic transfer and biomagnification in food webs within a tropical embayment as evidenced by nitrogen and carbon stable isotope analysis

Mercury (Hg) contamination in marine ecosystems poses a significant environmental threat due to its high toxicity, persistence in the environment, and tendency to bioaccumulate in organisms and biomagnify in food webs. Understanding how Hg moves through these food webs is essential for assessing its ecological and health impacts. To investigate the trophic dynamics of Hg in Rayong Bay, Gulf of Thailand, we collected marine organisms from the pelagic and benthic food webs during 2022-2023 and analyzed the total mercury content (THg) in plankton (phytoplankton, zooplankton, and fish larvae) and in 81 marine animal species. Furthermore, the stable nitrogen and carbon isotope values (δ15N and δ13C) were measured to establish their trophic levels (TLs) and potential food sources in the food web. Based on these analyses, we calculated the biomagnification factor using TL-adjusted ratios (BMFnorm) and trophic magnification factor (TMF) for the different TLs. BMFnorm values exceeded 1.0 in over 40 % of cases for both the pelagic and benthic food webs, indicating THg biomagnification from prey to predator. Notably, the pelagic food web exhibited a markedly higher TMF value (TMF = 6.68) compared to that of the benthic food web (TMF = 2.06), suggesting stronger Hg biomagnification within the pelagic food web. Our findings also highlight the consumption risk of Hg in some fish species in the Rayong Bay food webs, emphasizing the need for continued monitoring and mitigation strategies to safeguard both human and ecological health.

Trace elements contamination in fish and human health risks from the upper reaches of the Pearl River Basin

Evaluating the concentration of trace elements in fish in the river is crucial for assessing the potential risks to humans from eating fish. In this study, we collected 315 muscle samples of seven indigenous fish species Abbottina rivularis (Basilewsky, 1855), Cobitis taenia (Linnaeus, 1758), Hemiculter leucisculus (Basilewsky, 1855), Misgurnus anguillicaudatus (Cantor, 1842), Oreochromis mossambicus (Günther, 1889), Rhinogobius cliffordpopei (Rutter, 1897), Rhinogobius giurinus (Nichols, 1925) from the upper reaches of the Pearl River Basin in July, August of 2017 to investigate the concentration of zinc (Zn), copper (Cu), chromium (Cr), cadmium (Cd), lead (Pb), arsenic (As), and mercury (Hg) and further evaluate their health risk to humans. Trace elements analysis revealed that the average concentration of Zn (9.56 ± 3.72 mg/Kg) was the highest, followed by Cr (1.67 ± 1.15 mg/Kg), Cu (0.47 ± 0.44 mg/Kg), Pb (0.78 ± 0.12 mg/Kg), Cd (0.06 ± 0.11 mg/Kg), As (0.19 ± 0.56 μg/Kg), and Hg (0.01 ± 0.03 μg/Kg). As the hazard quotient index is <1, the THQ and TTHQ associated with fish consumption represent a negligible non-carcinogenic risk to the health of local consumers. Instead, Cr (cancer risk value: 2.72 × 10-4) and Cd (cancer risk value: 2.72 × 10-4) pose a potential cancer threat to local residents who eat the fish studied, and it needs more attention in the monitoring of the aquatic product on human health. Our study could be utilized to implement essential interventions in ecological security and protection, and preventing the emergence of adverse situations.

Bioaccumulation and potential human health risks of PAHs in marine food webs: A trophic transfer perspective

Polycyclic aromatic hydrocarbons (PAHs) are persistent pollutants in aquatic environments that can accumulate in marine organisms and pose potential health risks to humans through trophic transfer in the food webs. However, the accumulation and health risks of PAHs in organisms at different trophic levels remain unclear. This study investigated the accumulation and trophic transfer of PAHs in 40 marine organisms from Beibu Gulf (China), and assessed their health risks. Utilizing the trophic level spectrum constructed with stable isotope methods, the organisms were categorized into three trophic levels: Omnivorous (15.00 %), low-level carnivorous (67.50 %), and mid-level carnivorous (17.50 %). The contamination levels of total PAHs in these organisms ranged from "mild pollution" to "moderate pollution", with all organisms exhibiting significant PAH accumulation (Bioconcentration factor value > 2000). Total PAH concentrations increased with higher trophic levels, following the trend of mid-level carnivores > low-level carnivores > omnivores. Notably, only three PAH compounds (Nap, Fla and Phe) showed biomagnification effects, while the others exhibited trophic dilution. Carcinogenic risk assessment indicated an "Unacceptable risk" level for all populations, with the highest risk due to consumption of mid-level carnivorous. These findings offer new insights into the accumulation and health risks of PAHs from a trophic transfer perspective.

Unveiling the nutritional value and potentially toxic elements in fish species from Miliç Wetland, Türkiye: A probabilistic human health risk assessment using Monte Carlo simulation

This study evaluates the nutritional value and health risks of fish from Miliç Wetland, Türkiye, focusing on potentially toxic elements (PTEs) in Esox lucius, Squalius cephalus, and Carassius gibelio. Using ICP-MS, mean PTE concentrations were determined, including Zn (4979 μg/kg), Fe (4241 μg/kg), and As (125 μg/kg). Macro elements like K, P, and Ca were also assessed for nutritional profiling. A Monte Carlo-based risk assessment confirmed that PTE levels were below safety limits, indicating safe consumption. Chemometric techniques (PCA, PCC, HCA) helped trace contamination sources, identifying residential, agricultural, and lithogenic inputs. Esox lucius showed the highest essential nutrient levels. This research highlights the importance of combining chemometric analysis with regular monitoring for food safety and public health protection.