The hydromedusa Blackfordia virginica is an invasive species that has disrupted coastal marine food webs throughout the world. Here, we report the response of plankton community to B. virginica blooms in a subtropical lagoon in China. Chlorophyll-a concentrations increased after the peak of B. virginica abundance, which was coincident with high concentrations of ammonium. An increase of the biomass and composition of pico- and nano-phytoplankton during the bloom resulted from bottom-up effects due to the nutrients excreted by B. virginica. The average size and grazing rates of microzooplankton concurrently decreased. The negative correlation between the abundances of B. virginica and microzooplankton was accurately simulated by a generalized linear model and redundancy analysis. This study provided empirical evidence of the impacts of the B. virginica bloom on the food web and the mechanisms responsible for those effects. These impacts may lead to serious ecological and environmental consequences for the lagoonal ecosystem.

Eighteen trace elements were analyzed in a 120-year sediment core from Daya Bay. Burial flux history and potential provenance, the relationships among trace elements, and biogenic compositions were analyzed for determining the trend and extent of trace element accumulation and identifying corresponding anthropogenic effects. Additionally, the effects of anthropogenic activities on Daya Bay were reconstructed, and a baseline/background estimation was provided for Daya Bay. The burial fluxes of V, Cr, Cd, Cu, Zn, Mn, Fe, Co, Ni, Pb, Hg, Zn, Mo, Ag, As, Se, and Tl increased from 1960 to 2010, especially after the late 1980s. Our results are useful for understanding pollution and land-sea interactions along the coasts of the South China Sea, especially in the Guangdong-Hong Kong-Macao Greater Bay Area.

Statistically distinct ‘high’, ‘moderate’ and ‘low’ metal contamination positions were distinguished across five Sydney estuary embayments for total sedimentary metal concentrations of Ni, Pb and Zn. While statistically distinct total sedimentary As, Cd, Co and Cu concentrations were indicated for the ‘low’ position samples. Mangrove (Avicennia marina) pneumatophore tissue metal concentrations from ‘high’ position trees were statistically distinct for Cd, Ni, Pb and Zn, while root tissue samples from ‘low’ position trees were statistically distinct for As, Cd and Zn. Outcomes from CAP, simple linear regression and DISTLM modelling indicated sedimentary metals were predominantly assimilated into mangrove root tissue, with smaller uptake into pneumatophore tissue. A comparison of floristic tissue metal concentrations indicated mangrove (A. marina) root tissue assimilated higher sedimentary metal concentrations than leaf and root tissue of seagrasses (Zostera capricorni and Halophila ovalis), which had relatively higher metal concentrations than those from pneumatophore and leaf mangrove tissue.

Gillnets can cause impacts on marine ecosystems when they become abandoned, lost or otherwise discarded fishing gear (ALDFG). Fishing gear marking is a tool to address ALDFG and its impacts. This study aims to compare the characteristics and fishing activities of fishers in small-scale fishery (SSF) and industrial fishery (IDF) as well as their viewpoints on fishing gear marking practice. Data were collected during July-November 2020 from 95 fishers in five coastal provinces of Thailand. Most fishers used crab gillnets; besides, fishing capability and intensity of fishers in IDF were higher than in SSF. Awareness of fishing gear marking practice of fishers in IDF was higher than in SSF, but acceptance was not different. Preferred material was fabric for fishers in SSF and plastic for fishers in IDF. Most fishers anticipated government as producer. Moreover, further studies are needed to develop suitable materials, installation and cost for fishing gear marking.

The commercially important marine microalgae Nannochloropsis oceanica is easily ingested by protozoan predators during large-scale cultivation. However, investigations into the effect of microalgae on the growth of protozoa are scant. A feeding experiment was conducted with Euplotes vannus grazing on different concentrations of N. oceanica. The ciliate population was significantly lower in the high concentration of algae than that in the low or medium algal concentration treatments. The density of ciliates cultured in algae filtrate media was significantly lower than that in lysate media and the blank control. Furthermore, the algal cell filtrate was added to three other protozoan populations, and they all gradually lost their ability to move and their body shape changed. This study investigated the interactions between N. oceanica and protozoan predators and provides insight on using microalgal extracellular substances to control biological contamination in the future.

Squids are globally distributed. Hg-contaminated squids may have high risks on humans. With abundant Se (antagonistic effect on Hg), the risks can be reduced. We collected squids around the world (Northwest Pacific Ocean, Southeast Pacific Ocean and Indian Ocean). Concentrations of Hg and Se were region-based and tissue-based. The higher content of Se were, the lower relative Hg levels were. The correlation between Se:Hg and Se was the strongest in the digestive gland. The values of Se:Hg and THQ all confirm that the health risk was lower in samples with higher concentrations of Se. Despite the risk assessment by Se:Hg, BRV and THQ analysis showed no risk when consumed in moderation, the maximum daily intake is provided based on Monte Carlo simulation. In future, when evaluating the risks cause by Hg exposure and providing the recommended daily amount, it may need to concurrent consideration of Se levels.

Plastic pollution is ubiquitous and not even remote protected islands are safe from it. Floating debris can adsorb toxic compounds that concentrate on their surface, being available to the animals that ingest them. For this reason, a baseline study of plastic pollution was conducted in the remote Revillagigedo Archipelago, in the Mexican Pacific Ocean. In 47 manta net samples an average of 4.8 plastics/1000m² was found, 73% of the pieces being <5 mm. Polyethylene and polypropylene were the most common polymers found. The chemical analysis of organic pollutants revealed that organochlorine pesticides, polycyclic aromatic hydrocarbons and polychlorinated biphenyls are adsorbed on the plastics collected in the area. Filter feeding megafauna such as humpback whales, manta rays and whale sharks could ingest contaminated micro and macroplastics. Plastics were found also on the beach, where they are available to the ingestion by terrestrial animals, including endemic species endangered to extinction.

Marine litter accumulates in coastal dunes and causes severe damages to these fragile ecosystems. This study analyzed the composition, cover and distribution of marine litter and its relation to vegetation cover in a Mediterranean dune system, located in a protected area facing the Ligurian Sea (Northern Italy). We sampled twenty-two permanent multiscale plots in spring and autumn. Litter was detected in all plots and artificial polymer materials were the dominant type (85%). Litter categories increased from spring to autumn mainly due to seaside tourism. The largest spatial scale (16 m²) explained the variability in waste composition better than the smaller ones (4 m², 1 m²). Finally, the vegetation cover correlated inversely with the turnover of litter categories, suggesting that plants may act as a barrier to litter transport by trapping it, and that they play a role in the spatio-temporal dynamics of coastal litter.

The Puerto Velero Marina, located on the central Caribbean coast of Colombia, is an example of an artificial structure that serves as a substrate for a vulnerable community such as cnidarians (Hydrozoa and Anthozoa). This study provides the first assessment of corals and other cnidarians inhabiting artificial marine habitats in a marginal environment of the Caribbean of Colombia. The Puerto Velero Marina was built into a 7 km² sand spit generated by sedimentation at the mouth of the Magdalena River. In this study were recorded 14 cnidarian species, among which were found 48 small colonies of scleractinian corals such as Porites, Siderastrea, Phyllangia, and Astrangia. This initial biodiversity assessment of the artificial structure provides a baseline that highlights the importance of further monitoring programs to identify non-native species that could reach this kind of hard structures.

The present study aimed to determine the total organic carbon (TOC), total nitrogen (TN), the carbon‑nitrogen ratio (TOC/TN), carbon isotope (δ¹³C), and nitrogen isotope (δ¹⁵N) in five sediment cores collected from upstream to downstream of the Rio Serinhaem estuary, State of Bahia, Northeast Brazil, in order to investigate the origin of the deposited organic matter (OM).Significant positive correlation was found between TOC and NT (rₛ = 0.75); TOC/TN and TOC (rₛ = 0.64); δ¹⁵N and TOC (rₛ = 0.72); and δ¹⁵N and TOC/TN (rₛ = 0.63). The values of δ¹³C and δ¹⁵N found are characteristic of terrestrial sources. The TOC/TN ratio confirmed the data found for δ¹³C and δ¹⁵N, which recorded the origin of organic matter from terrestrial C3 type plants. Upstream of the estuary, the highest means of TOC/TN were found (T1 = 36.9 and T2 = 24.4), as reflected by the increase in TOC content or reduction in TN. The OM along the estuary is predominantly from plants with a C3 photosynthetic pattern, indicating that the Serinhaem River estuary is considered a relatively well-preserved environment.