Increasing global concern has been raised about the expansion of hypoxia in coastal waters and its potential to impact benthic ecosystems. Upwelling areas offer opportunities to study the effects of hypoxia on benthic communities under natural conditions. We used a biological trait-based approach and estimated functional diversity indices to assess macrobenthic community functioning along a depth gradient associated with naturally increasing hypoxia and concentrations of organic matter in the upwelling zone of northern Chile (South-East Pacific) over two years. Our results highlighted the increasing dominance of opportunistic biological traits associated with hypoxia and high organic matter content. Habitat filtering was the main process affecting the studied communities. Functional diversity patterns were persistent overtime despite the occurrence of a pulse of oxygenation. This study contributes to our understanding of how natural hypoxia impacts macrobenthic communities, providing useful information in the context of increasing eutrophication due to human influence on coastal areas.

In this work, established treatment processes for microplastics (MPs) and nanoplastics (NPs) in water as well as developed analytical techniques for evaluation of the operation of these processes were reviewed. In this regard, the strengths and limitations of different qualitative and quantitative techniques for the analysis of MPs and NPs in water treatment processes were first discussed. Afterward, the MPs and NPs treatment processes were categorized into the separation and degradation processes and the challenges and opportunities in their performance were analyzed. The evaluation of these processes revealed that the MPs or NPs removal efficiency of the separation and degradation processes could reach up to 99% and 90%, respectively. It can be concluded from this work that the combination of separation and degradation processes could be a promising approach to mineralize MPs and NPs in water with high efficiency.

We investigated the temporal concentration of floatable plastic particles in the Po river, the largest contributor of freshwater to the Adriatic Sea. Surface waters were sampled in 2019 with a Manta trawl, with almost bimonthly frequency. In total, 5063 plastic particles were collected, 80.6% of which were microplastics (<5 mm). Characterization through FT-IR spectroscopy evidenced 7 polymers, of which polyethylene, polypropylene and polystyrene accounted for 40.5%, 25.7%, and 14.9%, respectively. The highest plastic concentration was recorded in December (3.47 particles m⁻³; 5.89 mg m⁻³), while the lowest in August (0.29 ± 0.01 particles m⁻³; 0.22 ± 0.08 mg m⁻³). We estimated the annual load of floatable plastic particles carried by the Po river to be 145 tons. Plastic particle load was correlated with the hydraulic regime, and was higher in autumn and spring months.

Southwest Nova Scotia (SWNS) is Canada's most productive lobster (Homarus americanus) fishing region. Abandoned, lost, and discarded fishing gear (ALDFG) is widespread. This baseline study provides the first preliminary assessment of environmental and economic impacts of ALDFG on the commercial lobster industry in SWNS. Fishers conducted 60 retrieval trips, searched ~1523 km² of the seafloor and removed 7064 kg of ALDFG (comprising 66% lobster traps and 22% dragger cable). Results showed that lost traps continued to capture target and non-target species until gear degraded. A total of 15 different species were released from retrieved ALDFG, including 239 lobsters (67% were market-sized) and seven groundfish (including five species-at-risk). The present findings, combined with information on regional fishing effort and market prices, estimate that commercial losses from ALDFG can exceed $175,000 CAD annually. This baseline assessment provides useful data for government and commercial fishing stakeholders to improve ALDFG management.

Variation in water quality can directly affect the composition of benthic assemblages on coral reefs. Yet, few studies have directly quantified nutrient and suspended particulate matter (SPM) to examine their potential impacts on benthic community structure, especially around high oceanic islands. We assessed the spatio-temporal variation of nutrients and SPM across six sites in American Samoa over a 12-month period and used exploratory path analysis to relate dissolved inorganic nutrients, land use, and natural and anthropogenic drivers to benthic assemblages on adjacent shallow reefs. Multivariate analyses showed clear gradients in nutrient concentrations, sediment accumulation and composition, and benthic structure across watersheds. Instream nutrients and land uses positively influenced reef flat nutrient concentrations, while benthic assemblages were best predicted by wave exposure, runoff, stream phosphate and dissolved inorganic nitrogen loads. Identifying locality-specific drivers of water quality and benthic condition can support targeted management in American Samoa and in other high islands.

Microplastics in the ocean are threatening marine ecosystems. Although plastic contaminants are ubiquitous, their distribution is thought to be heterogeneous. Here, we elucidate the spatial and temporal variations in the quanti-qualitative characteristics of microplastics near Kyushu, Japan in the East China Sea. Six surveys across nine stations were conducted over a 14-month period, and a total of 6131 plastic items were identified. The average microplastic abundance and size were 0.49 ± 0.92 (items·m⁻³ ± S.D.), and 1.71 ± 0.93 (mm ± S.D.), respectively. Differences between the highest and lowest abundances were 50-fold among monthly means, and 550-fold across all net tows. With respect to colour, polymer type, and shape, white and transparent polyethylene fragments were the dominant composition. There were significant differences for each of the analytical microplastic parameters among the survey months. Our results provide baseline data and lead to a more comprehensive understanding of the spatiotemporal characteristics of microplastic pollution.

This study aimed to determine the presence of MPs in the gut and muscle tissue of riverine fish collected from the Qarasu River, Kermanshah, Iran. The results highlighted that MPs were found in the gut and muscle of all fish species at an average abundance of 8.12 ± 4.26 P/individual and 0.85 ± 0.38 P/g muscles, respectively. High amounts of MPs were found in the range of 1-25 μm in terms of size distribution. The properties of MPs extracted indicated that PE, PP, PS, and PA in the monotype of fiber and fragment were the most abundant plastic types and shapes found. Additionally, EAI was calculated for MPs found in the muscle. So, 174.43 and 127.19 P/kg/bw/year (1.28 and 0.93 g/kg/bw/year), were intake by two groups of adults and children, respectively. These findings highlight the contamination of fish as a common source of marine food in home consumption and the probability of entrance into the human diet.

This paper studies the activity of natural and technogenic radionuclides in bottom sediments and surface water of the Pechora River estuary, which is the largest Arctic river within the European part of Russia. The relevance of conducting radioecological studies of this region is associated with active oil and gas activities in the Pechora basin and the presence of potential sources of radiation hazard. The average activities of ¹³⁷Cs, ²²⁶Ra, ²³²Th, and ⁴⁰K in bottom sediments were 0.16, 18.72, 13.36, and 373.59 Bq·kg⁻¹, respectively. The average activity of ²²⁶Ra in the bottom sediments of the Pechora delta was two times higher than in other rivers of the Arctic basin of the European part of Russia, which is associated with oil and gas activities that are carried out in the Pechora basin. This is due to the fact that the decay products of uranium are the main by-products of oil and gas production. The specific activity of technogenic ¹³⁷Cs in bottom sediments of the Pechora River delta was low and did not exceed 2.2 Bq·kg-1. We did not detect any radioactive ⁹⁰Sr in bottom sediments. The low ¹³⁷Cs activity in the bottom sediments of the Pechora delta was associated with both the larger granulometric composition of the sediments in comparison with the estuaries of the Siberian rivers, and with low concentrations of ¹³⁷Cs in the terrigenous material (soil) entering the river from the catchment area. This was due to the low levels of ¹³⁷Cs contamination in the soil of the Pechora river basin. We did not find any negative radiation effects of the underground nuclear explosion “Pyrite” carried out in the northern part of the delta, since there were no other technogenic radionuclides. The values of the radionuclides ³H, ¹³⁷Cs, ²²⁶Ra, ²³²Th and ⁴⁰K, as well as the total alpha activity in the surface waters of the Pechora River delta, turned out to be below the detection limit. In surface waters, we were able to determine only the total beta activity, which varied over a range from 19.6 to 59.6 Bq·m⁻³ with an average value of 33.9 Bq·m⁻³, which was significantly lower than the radiation safety standards. The values of the radiation hazard parameters were below the world average levels and were not significantly hazardous to the health of people living in the area of the Pechora River delta. We concluded that at present, in the Pechora River delta, there are pastures for reindeer with low levels of natural and man-made radioactivity. These conducted studies are the source material in a series of comprehensive studies of the current radioecological state of the tundra territories of the European part of Russia.

This study aimed to assess the condition of the Dasun estuary, Indonesia, from the influence of heavy metals Cr, Cd, and Pb that accumulated in sediments and beach morning glory vegetation (Ipomoea pes-caprae). The results showed that the metal concentrations of Cr, Cd, and Pb in the sediments were 3.39–5.29 mg/kg, 0.21–0.29 mg/kg, and 5.36–6.87 mg/kg, respectively. The concentrations of metals that accumulated in the tissue of entire plants were 0.98–1.22 mg/kg (Cr), 0.31–0.40 mg/kg (Cd), and 0.94–1.23 mg/kg (Pb). Dasun estuary is still in the safe category for the living habitat, even though the concentration of Cd was relatively high and was estimated to originate from batik industry waste. The vegetation of Ipomoea pes-caprae was found to have a high ability to absorb Cd; thus, it can be used as a bioindicator for heavy metals in the environment.