Distributions and variations of biogenic sulfur compounds including dimethylsulfide (DMS), dissolved and total dimethylsulfoniopropionate (DMSPd and DMSPt) and acrylic acid (AA) were investigated in coastal waters off Qingdao, China during the late-bloom and after-bloom periods of the Ulva prolifera bloom of 2015. DMSPd, DMS and AA concentrations after the bloom were significantly higher than during the late-bloom, but DMSPt concentrations in surface waters began to decrease. High concentrations of these compounds in the surface layer were associated with the bloom, with the exception of increased concentrations of DMSPt in the middle layer as decaying U. prolifera debris settled. The sea-to-air fluxes of DMS were estimated to be 18.08 and 24.24 μmol m⁻² d⁻¹ during the late-bloom and after-bloom, and about three times higher than the reported average fluxes of the Yellow Sea, which highlighted the impacts of U. prolifera blooms on DMS emissions.

This study reports on the ingestion of microplastics by the alien fish Pirapitinga, Piaractus brachypomus (Characiformes; Serrasalmidae) that escaped Vembanad lake, the largest brackish water lake in the south-west coast of India, from the aquaculture systems during flooding. Microplastics separated from the gut of 32 out of the 123 fishes (26%) examined were identified using Attenuated Total Reflectance – Fourier Transform Infrared (ATR-FTIR), and Raman Spectroscopy. In total, 69 microplastic particles, represented by fibers, foam and fragments were recovered from the fish, with sizes ranging from 0.89 to 4.85 mm. The ATR-FTIR spectral analyses revealed the presence of polymers polyethylene and Nylon 6. The occurrence of PP, Nylon 6, PET and PBT were confirmed using Raman spectroscopy. The presence of MPs in the gut content of alien fish P. brachypomus could be a reflection of the increasing microplastics pollution in the estuaries and backwaters along the south-west coast of India.

Marine bivalves are often used as a sentinel species in coastal environmental monitoring since changes in the environmental quality are often well preserved in their cells and tissues. Anadara and Tegillarca species of Arcidae, the blood cockles, are considered to be good sentinel species in monitoring coastal pollution and ecosystem health because they are distributed widely in the subsurface of intertidal mudflats. Internal cellular defense of the blood cockles to physical and biological stresses is mediated by the circulating hemocytes, while their hemocyte types and functions are poorly studied. In this study, we first characterized morphology and immune-related activities of hemocytes of three common blood cockles Anadara broughtonii, A. kagoshimensis, and Tegillarca granosa using flow cytometry. Based on cell morphology and immunological functions, we described five types of hemocytes identically in the three blood cockles: erythrocytes type-I (erythrocytes-I), erythrocytes type-II (erythrocytes-II), granulocytes, hyalinocytes, and blast-like cells. Erythrocytes were round cells containing hemoglobin with numerous granules in the cytoplasm and these cells consist of two central populations. Erythrocytes-I were the most abundant cells accounting for 80–89% of the total circulating hemocytes and exhibited a certain level of lysosome and oxidative capacity. Erythrocytes-II were the largest cells and displayed high lysosome content and the most active oxidative capacity. Both erythrocytes-I and erythrocytes-II did not show phagocytosis capacity. Granulocytes were intermediated-sized hemocytes characterized by granules in the cytoplasm and long pseudopodia on the cell surface, and these cells were mainly engaged in the cellular defense exhibiting the largest lysosome content, the most active phagocytosis, and high oxidative capacity. Contrary to granulocytes, hyalinocytes were comparatively small and round cells and exhibited no granules in the cytoplasm. Hyalinocytes displayed a certain level of lysosome and phagocytosis and oxidative capacities. Blast-like cells characterized by the smallest size and small quantity of cytoplasm and exhibited an absence of phagocytosis and extremely low oxidative capacity, suggesting that this population is not directly involved in the cell-mediated immune activities. In conclusion, flow cytometry indicated that three blood cockles had five types of hemocytes, and the erythrocytes and granulocytes were mainly involved in the immunological activities.

Global increase in the use of pharmaceutically-active compounds (PhACs), and their insufficient removal in wastewater treatment plants, have resulted in their continuous release into the marine environment. We investigated the use of the solitary ascidians Herdmania momus, Microcosmus exasperatus, and Styela plicata as bioindicators of three common PhACs in the Israeli coastal waters: Bezafibrate, carbamazepine and diclofenac. Both the Mediterranean and the Red-Sea coasts were found contaminated with PhACs, detected at all 11 sampling sites, with four sites contaminated with all three studied PhACs. Diclofenac was most frequent, present in nine of the 11 sites with concentrations reaching 51.9 ng/g of dry weight sample (dw). Bezafibrate and carbamazepine reached concentrations of 47.8 ng/g dw and 14.3 ng/g dw, respectively. The alarming detection of such high concentrations of PhACs in ascidians along Israel's coasts demonstrates both the extent of PhACs contamination in the region, and the potential of ascidians as bioindicators, and emphasizes the urgent need for additional research into PhAC contamination sources and effects.

This study explores methods to estimate minimum drift times of ghost nets found in the Maldives with the aim of identifying a putative origin. We highlight that percentage cover of biofouling organisms and capitulum length of Lepas anatifera are two methods that provide these estimates. Eight ghost nets were collected in the Maldives and estimated drift times ranged between 7.5 and 101 days. Additionally, Lagrangian simulations identified drift trajectories of 326 historical ghost nets records. Purse seine fisheries (associated with Korea, Mauritius, the Philippines, Spain, France and Seychelles) and gill nets from Sri Lanka were identified as 'high risk' fisheries with regard to likley origins of ghost nets drifting into the Maldives. These fisheries are active in areas where dense particle clusters occured (drift trajectories between 30 and 120 days). Interestingly, ghost nets drifting less than 30 days however, remained inside the exclusive economic zone of the Maldivian archipelago highlighting potential illegal, unreported and unregulated fishing activity is occuring in this area. This study therefore points to the urgent need for gear loss reporting to be undertaken, especially by purse seine and gill net fisheries in order to ascertain the source of this major threat to marine life. This should also be coupled with an improvment in the data focused on spatial distribution of the abandoned, lost or discarded fishing gear originating from both large- and small-scale fisheries.

The Bohai Sea is well-known as a source of atmospheric methane (CH₄). However, the main regulate factors of the spatiotemporal distribution of CH₄ and its sea-to-air flux remain largely unknown. In this study, the observed CH₄ concentration ranged from 4.8 to 32.7 nmol/L and 3.1 to 15.2 nmol/L in August and November of 2014, respectively. The main factors that influence the distribution of CH₄ and its sea-to-air flux were stratification, solubility, and current structure for the mid-west depression basins, the permanent well-mixed seawater column and CH₄ source strength for the centre shallow ridge zone, and the upwelling for the east depression basin, respectively. Meanwhile, wind also plays an important role in sea-to-air CH₄ flux in the study area except the centre shallow ridge zone. Upwelling made the east depression basin the most intensive source of CH₄, with a flux of 2 to 4 times higher than the other sub-regions.

Accurate estimation of the biomass of raft-attached green algae is important for predicting the scale of green-tides in the Yellow Sea, China. In this study, two different biomass estimation methods are proposed: green algae attached to nursery-net (GAAN) and green algae attached to rope (GAAR). The GAAN method involves the use of images obtained using an unmanned aerial vehicle (UAV), high-resolution satellite images, and data from a statistical yearbook. The GAAR method uses high-resolution satellite images and data from a field sample survey. The results showed that the biomass of GAAN and GAAR in the Subei Shoal during 2017 was 8868 tons and 2974 tons respectively. A longer-term study of the biomass of GAAN and GAAR could provide quantitative information for the earnings forecasts of Porphyra yezoensis and for green-tide prevention.

Anthropogenic sound can affect fish behaviour and physiology which may affect their well-being. However, it remains a major challenge to translate such effects to consequences for fitness at an individual and population level. For this, energy budget models have been developed, but suitable data to parametrize these models are lacking. A first step towards such parametrization concerns the objective quantification of behavioural states at high resolution. We experimentally exposed individual Atlantic cod (Gadus morhua) in a net pen to the playback of seismic airgun sounds. We demonstrated that individual cod in the net pen did not change their swimming patterns immediately at the onset of the sound exposure. However, several individuals changed their time spent in three different behavioural states during the 1 h exposure. This may be translated to changes in energy expenditure and provide suitable input for energy budget models that allow predictions about fitness and population consequences.

Trace elements can be accumulated from coastal environment by aquatic organisms from their food and be transferred throughout the food webs. Studying the effects of salinity on the trophic transfer of trace elements in a euryhaline fish, able to deal with large variations in salinity, is therefore key to understand their dynamics in aquatic environments. In this context, we investigated the potential influence of salinity on the trophic transfer of two essential elements (Mn and Zn) in the euryhaline fish, the turbot Scophthalmus maximus using radiotracer techniques. After acclimation to three salinities (10, 25 and 38), turbots were fed with radiolabelled pellets (⁵⁴Mn and ⁶⁵Zn). Kinetic parameters of depuration were determined after a 21-d period and trophic transfer factors were calculated. Trophic transfer of Mn at the highest salinity was significantly lower than for the other conditions whereas salinity did not significantly influenced Zn trophic transfer. Differences in the processes involved in the regulation (homeostasis) of the two tested trace elements may explain the contrasting influence of seawater salinity for Mn and Zn.