Global plastics production is increasing exponentially and contributing to significant pollution of the marine environment. Of particular concern is ingestion and entanglement risks for marine wildlife, including when items such as rope are incorporated into nest structures. These events are commonly documented using photographic and visual surveys, and each presents a number of challenges and benefits for species conservation and monitoring. Here we compare an invasive (i.e., removing debris from nests) and non-invasive (i.e., photographs) sampling method for quantifying nest debris using the silver gull (Chroicocephalus novahollandiae) as a case study. Overall, 17 debris items were detected in 9% of gull nests. While the use of photographs to monitor nest debris is increasingly popular, the invasive method detected one additional debris item not identified using photography. We therefore recommend caution for nest debris and other monitoring programs where identifying small or cryptic items may require a high level of skill.

The accumulation of marine litter on coastal seabeds is influenced by various anthropogenic and environmental factors. To identify litter accumulation areas on the seafloor, it is necessary to understand the interaction of these parameters. This study analyses the seafloor litter occurrence in the southeastern North Sea, based on samples collected between October 2017 and March 2019. Litter data were combined with hydrographic, high-resolution in situ measurements and further geographic as well as anthropogenic factors for statistical analyses. Benthic litter showed a mean density of 2473 ± 3116 items km⁻², and plastics consisting mainly of fisheries-related items represented the majority of identified objects. The statistical analyses suggest that salinity and temperature gradients, the meridional bottom currents, as well as the distance of the station to the coastline have a significant effect on benthic litter abundance. Direct combination of litter sampling and hydrographic measurements can improve the understanding of seabed litter dynamics.

Coastal agricultural practices are often located in catchments upstream of ecologically important aquatic systems. Here, we investigate the occurrence of pesticides in a coastal creek flowing into a habitat-protected area within the Solitary Islands Marine Park, Australia. Water samples were collected from six sites along a creek transect during three sampling periods. Samples were analysed for 171 pesticide analytes, including organochlorines, organophosphates, herbicides, and fungicides. Five insecticides, two herbicides, and two fungicides were detected. The neonicotinoid imidacloprid was detected at 5 out of 6 sites, with concentrations reaching 294 μg L⁻¹, the highest yet detected in Australian waterways. The organophosphate insecticide dimethoate was detected at 4 sites, which occurred at the 2nd highest detected concentration in the study (12.8 μg L⁻¹). The presence of these pesticides in the aquatic environment downstream of horticulture in this and other regions may have serious implications for stream biota and ecologically important marine ecosystems.

Marine debris (MD) is a serious environmental concern globally. Yet, few studies have reported on MD in sanctuary zones of the Indian Ocean. Consequently, coastal transects were conducted to determine MD quantity, composition and distribution at northern Ningaloo Marine Park, Western Australia. Debris density ranged between 0.004 and 0.02 items m⁻² with the greatest density near Exmouth township. Composition was predominantly plastic (61%) with fishing-related items (25.5%) and plastic fragments/remnants (16%) the most numerous overall. Land-based and general sourced MD accounted for 88% of all debris. Debris levels were significantly lower at sites with higher visitation and increased distance from access points. There was no significant difference between sanctuary and non-sanctuary zones. Although not immune to MD, this study suggests its remote location, environmental awareness and management strategies implemented at Ningaloo Marine Park may be key to its low MD levels.

The establishment of water quality criteria (WQC) for copper (Cu) was used as the basis for an ecological risk assessment of marine Cu pollution in Liaodong Bay, China. Published ecotoxicity data for Cu were obtained and supplemented with the results of acute Cu toxicity tests. The marine WQC for Cu in Liaodong Bay was developed using a species sensitivity distribution method with a safety factor of 2.0 and the USEPA acute-to-chronic ratio method. The ecological risk of Cu in Liaodong Bay was assessed by comparing the seawater Cu concentrations with the developed WQC. The results of this study showed that the acute and chronic Cu concentrations in Liaodong Bay were 3.31 and 2.18 μg/L, respectively. Comparison of the WQC to Cu concentrations in the bay resulted in risk quotients slightly >1.0 and typically ≤2.0. These data suggest that certain organisms in Liaodong Bay are at risk. These results can assist in the development of a pollution control management approach for the bay.

Microplastic pollution in marine environment has been a growing public concern in recent years. This article analyzed the scientific literatures related to marine microplastics through a combination of social network analysis and bibliometrics. Researches related to microplastics have grown rapidly since 2011, with approximately two-thirds of the total number of articles published in the last three years. Researchers in United States and Europe have provided tremendous support, however, the efforts and progress of Chinese researchers cannot be ignored. Moreover, the international cooperation is getting closer, and related strategies are launched continuously. The results showed that Marine Pollution Bulletin is the most active journal. Through keyword analysis, we understand the development history and current hotspots of the whole microplastics researches, including ecological risks, interrelationship between microplastics and other pollutants, and detection methodology. Finally, some suggestions and perspectives for future microplastics research are provided.

Seasonal distribution of four metals (Cd, Cu, Pb, and Zn) in eight shellfish species collected from the heavily contaminated Cuddalore coast in Tamil Nadu, Southern India, were analyzed. Metal concentrations in all shellfish species were determined using atomic absorption spectrometry. All metals were present in all seasons in most of the species, however, with a few exceptions. Overall, the metal concentration was in the descending order: Zn > Cu > Pb > Cd. Metals might have emerged from both natural and anthropogenic sources as per multivariate statistical analysis. Bioaccumulation factor results showed that cadmium was more bioaccumulated and beyond the threshold limit. Hazard index (HI) values revealed that consuming shellfish from Cuddalore coast can pose hazards to human health, with all HI values beyond threshold limit across all seasons — premonsoon (1.33), monsoon (1.73), postmonsoon (2.55), and summer (2.64). It is evident that consumption of shellfish across all seasons may have adverse health impacts to the people.

Although the simplification of multivariate histopathological data into univariate indices can be useful for the assessment of environmental quality, this implies a great loss of information. The objective of the present study was to evaluate the effectiveness, in the context of environmental quality assessment, of an approach that integrates individual histopathological responses in a discriminated manner with the results of contaminants by means of multivariate analyses. This analysis was compared to the diagnosis of environmental quality provided by the use of the univariate Bernet histopathological index. Contaminant loads (sediments and fish) and the liver histopathology of Cathorops spixii were integrated through multivariate analysis. Integrated individual histopathological responses allowed classifying environmental quality from more to less impacted sites, while the univariate index showed some inconsistencies with chemical loads and allowed identifying only the most impacted site.

Microplastics pretreatment of prior to biodegradation is an efficient approach for their bioremediation. We isolated Achromobacter denitrificans from compost and used it for biodegradation of thermo-oxidative pretreated polyvinyl chloride (PVC) and low-density polyethylene (LDPE). About 12.3 % and 6.5 % weight loss, and 326.4 and 112.32 mg L⁻¹ extracellular protein were observed in bacterial flasks with PVC and LDPE, respectively. The pH in treated PVC reached to 5.12 and the thermal stability increased by 29 °C. The chemical modification in LDPE was demonstrated through oxidation of antioxidants (Phenol group), formation of new groups (Aldehyde group), and chain fracture in the main backbone by Fourier transform infrared spectroscopy. Formation of peaks at the range of 1700–1850 cm⁻¹ in LDPE attributed to formation of carbonyl groups as the degradation result. Scanning electron microscopy confirmed LDPE and PVC degradation by surface alterations. Consequently, thermo-oxidative pretreatment can be considered as a suitable strategy for improving microplastics biodegradation.

The structural characteristics of phytoplankton communities and their relationship with environmental factors were analysed based on survey data from the central South China Sea in summer 2020. A total of 416 separate taxa from 90 genera and 4 phyla were identified, with an average cell abundance of 572.98 cells/L. The dominant phytoplankton species were Nitzschia spp., Gyrodinium spp., Synedra spp. and Navicula spp. The Shannon-Wiener index ranged from 2.25 to 4.98, and the evenness index varied from 0.48 to 0.93. Correlation analysis showed that total cell abundance was negatively correlated with salinity, nitrate and silicate and was positively correlated with nitrite. Compared with the historical data, Thalassionema nitzschioides was cited repeatedly in previous researches as the dominant species. In addition, the Shannon–Wiener index showed an overall increasing trend over time, and the community structure is becoming more stable.