To investigate the impacts of sub-lethal concentrations of antibiotic agents in mariculture, culturable approach and DNA based detection were employed to isolate and analyse resistant bacteria and resistant genes in this study. Milkfish (Chanos chanos), the target rearing animal was exposed to sulfamethoxazole (SMX; 2 mg/L) for 8 weeks and resulted in reduced survival rate and weight gain to 61.9 % and 28.4 %, respectively compared to control milkfish (p < 0.001). The composition of SMX-resistant bacteria isolated from the culture water and the gastrointestinal tracts of milkfish underwent changes in response to SMX treatment with a reduced diversity. The prevalence of SMX resistant genes sul in bacterial isolates was elevated from 2.8 % of control to 100 % of SMX-administrated water. Exposure to SMX at a sub-lethal dosage enhanced the prevalence of resistance genes sul1 and sul2 in resistant bacteria, thus implying high frequency of resistance dissemination in the marine environment and surrounding ecosystems.

Strong stratification has formed in Lake Abashiri, a typical meromictic lake in Hokkaido, in the subarctic zone in Japan. When the anoxic water of the lower layer is upwelled to the surface by a strong wind, fish and corbicula clams die due to a lack of dissolved oxygen. This event is called as blue tide. It was observed that the dissolved methane in the lake decreased more than 100 t after the blue tide which occurred in 2008. This is the discovery of the phenomenon that a large quantity of methane diffuses to the atmosphere caused by upwelling of anoxic water which contains dissolved methane. We named the event as “methane burst”. It is also the first report that the wind-driven upwelling is reproduced using a numerical analysis code and the methane burst is analyzed. During this blue tide, the methane flux was approximately 170 times greater than usual.

Macroalgae and their rocky substrates both support diverse and abundant microbiota, performing essential ecological functions in marine ecosystem. However, the differences in the epiphytic microbial communities on macroalgae and rocky substrate are still poorly understood. In this study, the epiphytic microbial communities on four macroalgae (Corallina officinalis, Rhodomela confervoides, Sargassum thunbergii, and Ulva linza) and their rocky substrates from Weihai coast zone were characterized using high-throughput sequencing technology. The results showed that the alpha diversity indices were greater in rocky substrates than that in macroalgae. The microbial similarities among macroalgae and rocky substrate groups tended to decrease from the high taxonomic ranks to lower ranks, only 22.69% of the total amplicon sequence variants (ASVs) were shared between them. The functional analysis revealed that the microbiotas were mainly involved in metabolic activities. This study would provide the theoretical foundation for macroalgal cultivation and algal reef applications.

Istanbul needs to be protected and constantly monitored water resources due to its increasing population and the decrease in precipitation. This study aims to comprehensively reveal surface sediments collected from reservoirs that supply water to Istanbul concerning POPs (PAHs, PCBs, and OCPs) and heavy metals; to identify possible sources of PAHs, and conduct their ecological risk assessment. Pollution indices in this study were used as contamination degree (CD) contamination factor (CF), geoaccumulation index (Igₑₒ), pollution load index (PLI) and Sediment Quality Guidelines (SQGs). Total PAH concentrations of surface sediments at the sampling points ranged from 46.29 ng/g (A7) to 403.9 ng/g (A15). Benzo(b)fluoranthene (5.647–59.42 ng/g), Pyrene (3.625–83.10 ng/g), Fluoranthene (3.363–66.48 ng/g), Phenanthrene (3.115–52.48 ng/g), Chrysene (3.532–43.98 ng/g), Naphthalene (6.606–36.20 ng/g), Benzo(g,h,i)perylene (3.316–41.73 ng/g) and Indeno(1,2,3-c,d)pyrene (3.453–38.84 ng/g) are the dominant PAH compounds. PAH pollution may be caused by the village-town settlements near the dam and the O7-D020 highway. Total OCP concentration ranged from 2.233 ng/g (A12) to 7.337 ng/g (A1), while total PCB concentration ranged from 0.246 ng/g (A13) to 3.708 ng/g (A1). The lowest total OCP and PCB concentrations were found in surface sediments taken from Kazandere, Papuçdere and Alibey Dam lakes. DDT p,p (0.072–5.177 ng/g) has the highest concentration among all sediment samples. While the most dominant OCP compounds in the samples were DDT p,p, DDE p,p and DDD p,p, HCH alpha, HCH beta, respectively, PCB 153, 138 and 180 were the highest detected PCB congeners in the same samples. Total heavy metal concentration varied from 77,812 mg/kg to 267,072 mg/kg. According to PAH diagnostic analysis, the surface sediments of Terkos, Büyükçekmece, Elmalı, Darlık, Sazlıdere, Alibey and Ömerli Dams were polluted by petrogenic sources, while the surface sediments of Kazandere and Papuçdere Dams were affected by pyrogenic sources. None of the levels of POPs in the samples exceeded the ERM values. Slight and moderate contamination of heavy metals, such as Pb and Zn, were present in most of the sampling points according to CD, CF, PLI and Igₑₒ values. The quality criteria of heavy metals showed that almost all of the sampling points had Cd, Pb and Hg concentrations below the ERL values. The Ni concentrations at most of the sampling points significantly exceeded the ERM values. The concentrations of As, Cr, Cu and especially Ni and Zn exhibit a significant toxic risk to aquatic organisms to sediment quality criteria.

Organochlorine pesticides (OCPs) were investigated in surface sediments and seawater from three major estuaries at Cirebon coastal water, West Java Province, Indonesia. Total concentrations of OCPs in seawater and sediment varied from 10 to 120 ng/L (32 ± 36 ng/L) and 1.5 to 17 ng/g dw (mean of 7.4 ± 4.0 ng/g dw), respectively. OCPs concentrations in Sukalila estuary were higher than those detected in Bondet and Kejawan estuaries. The drins group was the predominant OCPs contaminant in seawater and sediment samples. Historical application of DDT, recent use of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), and application of technical hexachlorocyclohexanes (HCHs) are significant sources of DDTs and HCHs, respectively. The concentrations of γ-HCH and heptachlor epoxide in marine sediment elevated the value of Threshold Effect Limit (TEL) in 48% of the total study stations but lowered the value of Probable Effect Limit (PEL), suggesting that they ocassionally trigger adverse effects on benthic organisms.

The Red Sea is exposed to metals from a large variety of natural and anthropogenic sources. In this study, we analyzed 19 common element concentrations in 14 Red Sea zooplankton samples using inductively coupled plasma-optical emission spectrometry (ICP-OES). The average metal or metalloid concentrations of the Red Sea zooplankton were: Ca > Sr > Fe > Al > Zn > As > Cu > Mn > Cr > Mo > Ni > Pb > Cd. The As, Ca, and Cu concentrations significantly increased with increasing latitude, while Cd concentrations decreased (p < 0.01). Our study indicated that anthropogenic activities (i.e., cement factories and oil refining industries) might be the predominant sources of significantly high Cr (1718 mg/kg), Fe (11,274 mg/kg), Mn (57.3 mg/kg), Mo (286 mg/kg), Ni (226 mg/kg), Pb (332 mg/kg), and Zn (17,046 mg/kg) concentrations that recorded in the Central to North Red Sea zooplankton.

An impact assessment of oceanic effluent releases from Belmont wastewater treatment works (WWTW) in Newcastle, Australia, was undertaken. Benthic infaunal assemblages in sandy sediments of ~25 m water depth were examined, at sites adjacent to the release point, and at increasing distances up to 2 km in both a NE and SW direction over five consecutive years (2016–2020). Localised impacts were evident for infaunal assemblages, with sites within 20 m of the outfall (“Impact” site types) exhibiting lower taxa richness and Shannon diversity, higher abundances of polychaetes and/or nematodes, higher polychaete ratios, and shifts in assemblage composition in comparison to sites at greater distances during some years. Taxa with increased localised abundances at the outfall were identified as indicators for monitoring impacts, including deposit-feeding polychaetes (Families Polygordiidae, Paraonidae and Dorvilleidae) and Phylum Nematoda. Future infaunal monitoring could include molecular tools and paired sediment analyses.

Dredging is an excavation activity used worldwide in marine and freshwater environments to create, deepen, and maintain waterways, harbours, channels, locks, docks, berths, river entrances, and approaches to ports and boat ramps. However, dredging impacts on marine life, including marine mammals (cetaceans, pinnipeds, and sirenians), remain largely unknown. Here we quantified the effect of dredging operations in 2005 and 2019 on the occurrence of Indo-Pacific bottlenose dolphins (Tursiops aduncus) and long-nosed fur seals (Arctocephalus forsteri) in the Port River estuary, a highly urbanized estuary in Adelaide, South Australia. We applied generalised linear models to two long-term sighting datasets (dolphins: 1992–2020, fur seals: 2010–2020), to analyse changes in sighting rates as a function of dredging operations, season, rainfall, and sea surface temperature. We showed that the fluctuations in both dolphin and fur seal occurrences were not correlated with dredging operations whereas sea surface temperature and season were stronger predictors of both species sighting rates (with seals more prevalent the colder months, and dolphins in summer). Given the highly industrial environment of the Port River estuary, it is possible that animals in this area are habituated to high noise levels and therefore were not disturbed by dredging operations. Future research would benefit from analysing short-term effects of dredging operations on behaviour, movement patterns and habitat use to determine effects of possible habitat alteration caused by dredging.

Rivers are one of the main pollution routes to the ocean. This study examines the source of microplastics (MPs) in Jakarta Bay based on their characteristics and estimates MPs emissions from 9 estuaries around Jakarta Bay in 3 administrative areas (Tangerang, North Jakarta, and Bekasi). The sample used was the water's surface taken using a round net. The highest abundance was found in the Dadap River, and the lowest was in the Angke River. The characteristics of the MPs are dominated by fragments, the size of 300–500 μm, and composed of polyethylene. It shows that the MPs originate from the fragmentation of residents' plastic waste that has been in the waters for a quite long time. The nine estuaries also showed a high contribution to MPs in Jakarta Bay: from North Jakarta > Tangerang > Bekasi. The emission is highly correlated with water discharge and MPs' particles in each estuary.

PURPOSE OF REVIEW: Atmospheric aerosol from both natural and anthropogenic activities has long been acknowledged as one of the important factors influencing regional and global climate change. Many regions around the globe experienced high aerosol loadings because of intensive emissions, yet the roles of atmospheric aerosols in extreme meteorological and air pollution events have not been well demonstrated due mainly to the complexity of atmospheric physical and chemical interaction at mesoscale and even microscale. Here, we present a comprehensive review of current understanding on the role of atmospheric aerosols in the development and evolution of extreme meteorological events, including monsoon circulation, heat waves, extreme rainfall, tornadoes, and severe air pollution. RECENT FINDINGS: Aerosols could participate in the development of meteorological systems through direct and indirect effects. Large-scale precipitation from shallow stratiform clouds was found to be suppressed by aerosols, while invigoration effects contribute to deep convection and even catastrophic floods in local areas. The occurrence of high-impact weather such as tornadoes and tropical cyclone is also related to aerosol concentration and distribution. Moreover, a positive feedback between aerosols and boundary layer meteorology is proposed as an important factor conducive to heavy haze pollution over urban areas. The work underscores the great importance of aerosols’ meteorological feedback in extreme weather events. Integrated observations and seamless coupling of meteorology and atmospheric chemistry in models are highlighted for future studies to fill the knowledge gap in current research.