Underwater noise pollution is a recognized threat to marine life. In British Columbia, Canada, Pacific rockfish (Sebastes spp.) were historically overfished, prompting the establishment of Rockfish Conservation Areas (RCAs). However, there are no restrictions prohibiting vessel transits in RCAs. We hypothesized that RCAs do not protect rockfish from sub-lethal harm from noise. We compared noise levels at three RCAs with adjacent unprotected reference sites from August 2018–June 2019. While RCAs had lower levels of noise overall than reference sites, this trend was inconsistent; some RCA sites had higher levels of noise during certain time periods than non-RCA sites. A vessel noise detector was the best predictor of noise level over three frequency bands (20–100 Hz, 100–1000 Hz, 1–10 kHz), and predicted sound levels which could mask rockfish communication. We conclude that RCAs do not reliably protect rockfish from noise pollution, and recommend further study into potential impacts on stock recovery.

Daya Bay is a eutrophic coastal region with dynamic physico-chemical conditions influenced by terrestrial inputs and seawater intrusion. Zooplankton is a crucial trophic intermediary for energy transfer and fishery resources. In this study, we assessed the distribution and composition of zooplankton in Daya Bay during summer and winter of 2015. We found that zooplankton diversity was the lowest and dominated by small copepods (Acartia spp. and Paracalanus spp.) and gelatinous Oikopleura spp. under terrestrial inputs in the Dan'ao River estuary and Aotou barbour. The highest zooplankton diversity was observed at the bay mouth that influenced by salty intruded seawater, and the dominant oceanic species (such as Euchaeta concinna and Subeucalanus subcrassus invaded into the top of the bay in winter. The dominant species in the estuary shift from Penilia avirostris to Acartia spp. compared with historical researches, indicating the effect of human activities on the succession of dominant species.

The presence of polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethanes (DDTs) was determined in the sediments of Beibu Gulf, a newly developing industry and port in South China, to evaluate whether the rapid development of coastal cities has accelerated the organic pollution in the region. The levels of PCBs and DDTs ranged from 1.17 to 8.00 ng g⁻¹ and ND (not detected) to 3.82 ng g⁻¹, respectively. The levels were higher in the east of Beibu Gulf than in the west, which influenced by the industrialisation and urbanisation in the east. Additionally, penta-PCBs were the dominant PCB congeners, which are related to shipping activities, and DDTs may have originated from the historical use of technical DDT. The levels of pp′-DDD and PCBs did not have the potential to cause ecological risks in Beibu Gulf; however, residues of DDTs were at relatively higher ecotoxicological levels, thereby having the potential to cause adverse biological effects.

The purpose of this study was to elucidate the potential of using flounders as bioindicators of accumulation and transformation of POPs and to assess the possible environmental risk to the health of the population of the Russian coastal regions. The mean levels of HCH, DDT, and PCBs in the flounders were as follows: in the eastern Sea of Okhotsk, 49 ± 51, 62 ± 89, and 106 ± 83 ng/g lipid weight; in the southern Sea of Okhotsk, 36 ± 37, 15 ± 16, and 97 ± 41 ng/g lipid wt; in the Sea of Japan/East Sea, 62 ± 36, 39 ± 28, and 1616 ± 1177 ng/g lipid wt, respectively. In the Tatar Strait, OCPs were represented mainly by β-HCH with a concentration of 221 ± 182 ng/g lipid wt; the PCB level was 455 ± 317 ng/g lipid wt. Values of ILCR = 2.1·10⁻⁵ due to the consumption of flounder from the Sea of Japan/East Sea at a rate of 29 kg/yr indicate a probability of developing cancer during a lifetime.

Marine activities may cause the degradation of coral reefs. The composition of benthic communities and seawater quality have been commonly used as the proxies to assess the impacts of marine activities. However, these proxies may not be able to detect the subtle differences within homogeneous environment. We used photogrammetry to quantify the subtle differences of structural complexity between heavily and lightly trafficked sites at Wanlitong, southern Taiwan. Our study demonstrated that the impacts of marine activities can be detected within tens of meters through quantifying structural complexity of coral reefs. Vector ruggedness measure (VRM) is a more suitable metric than conventional linear rugosity to detect such impacts. The correlations between structural complexity and coral cover have variances while comparing with previous studies. The results show that using photogrammetry to quantify the structure of coral reefs can provide a novel aspect to evaluate the subtle differences caused by marine activities.

Thermal discharges from power plants elevate temperatures in the surrounding waters, and this warming of the marine environment inevitably influences phytoplankton communities. In this study, we conducted seasonal sampling in coastal waters of the Bohai Sea off Qinhuangdao, China. The results revealed that the coastal waters are notably affected by thermal discharge, with unseasonably-high water temperatures, particularly during winter. The change of phytoplankton community structure has been detected in the warmer coastal seawater. Although diatoms were the dominant species during field investigations, there were no significant seasonal changes in diatom abundance. In contrast, the density of dinoflagellates was low in all seasons due to the effects of thermal discharge. Consequently, the general trend in phytoplankton succession was interrupted. In general, the findings of this study may provide further insights into the warmer environmental impacts on phytoplankton communities in temperate regions.

It was studied for the effects of heavy metal stress on the antioxidant activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and lipid peroxidation (MDA) in the leaves of five mangrove plants. The results showed the protein concentrations were significantly higher in B. gymnorrhiza (7.55 mg prot /mL: Cu²⁺), K. obovata (11.21 mg prot/mL: Cd²⁺) and R. stylosa (12.51 mg prot/mL: Cd²⁺) (p < 0.05). Comparably, MDA contents were remarkably high in A. marina than other species under the same conditions (p < 0.05). The SOD, POD and CAT were observed to be significantly high in A. marina, A. corniculatum and B. gymnorrhiza under the same heavy metal treatment (p < 0.05). The PCA revealed that POD, SOD and MDA of five mangrove species were the major indices for response to heavy metal. And A. marina was more tolerant to heavy metal stress than others.

Floating Marine Litter (FML) are mainly plastics or synthetic polymers that float on the sea surface after being deliberately discarded or unintentionally lost along beaches, rivers or marine environments. In recent years, much focus has been placed on locating, tracking and removing plastic items in both coastal areas and in the open ocean. The use of high-resolution multispectral satellite images for such purpose is very promising, since satellite images can systematically monitor much larger areas in comparison to the traditional in situ observations. This paper contains a literature review of the published research regarding the optical remote detection of floating marine debris and the proposed associated methodologies. The main aim of this review is to compile all available information on detection methodologies, providing at the same time valuable insights into the different approaches used for floating marine litter monitoring. First, a brief introduction into the theoretical basis of a spaceborne floating marine litter detection system is given. Next, published articles, or relevant research work have been compartmentalised, for analysing the proposed procedures and assisting in a further assessment of their methodological frameworks. Lastly, conclusions and bottlenecks of the existing knowledge on marine litter detection from space are derived. Although the remote detection of floating marine litter is currently limited by inherent restrictions of the available satellite sensors specifications, we highlight how the methodological processing chain can significantly affect the future accuracy of plastic detection from space.

This study quantified the bioavailable nitrogen contribution from riverine plumes to Great Barrier Reef (GBR) coastal environments. The potential bioavailable nitrogen from two Dry Tropics riverine plumes was considerable [9 - 30% added to the end-of-catchment dissolved inorganic nitrogen (DIN) load]. Particulate inorganic nitrogen conversion to DIN was an important process in short timeframes (25% to 100% of the generated load). The remaining load was contributed by microbial mineralisation of organic nitrogen. Flood plume sediment has potential to generate nitrogen once deposited and/or resuspended. Nitrogen generation was insignificant in a few plumes where immobilisation of nitrogen in bacteria biomass occurred. The source of organic matter in the plumes and availability of nitrogen relative to organic matter were important determinants of mineralisation/immobilisation. This research demonstrates that riverine plumes have potential to be considerable sources of bioavailable nitrogen to coastal environments of the GBR and that organic matter is a key bioavailability driver.