Zooplankton assembly was characterized during the spring tide near a submarine outfall that discharges raw sewage directly into the southeastern portion of Guanabara Bay, near the Niterói, a highly urbanized center. The rain period directly influences water surface temperature and salinity, as has been previously observed in this bay. Dissolved oxygen (DO) and biochemical oxygen demand (BOD) were within the concentrations stipulated by the Brazilian legislation. The low chlorophyll a values observed herein may be associated with a nutritional imbalance to which phytoplankton may be subjected, observed through the carotenoid/chlorophyll ratio, which probably reflects zooplankton community composition. Twenty major zooplanktonic taxonomic groups were recorded, with a predominance of holoplanktonic taxa, mainly copepods. Mean zooplankton density and composition were in agreement with other studies in the region, however, these community characteristics at each of the sampling stations appear to be related to the urbanization degrees of each Niterói neighborhood.

Fifteen antibiotics, including seven sulfonamides (SAs); three macrolides (MLs); three quinolones (QNs); one lincosamide, lincomycin (LIN); and one tetracycline (TC), were detected in the surface water of the Xi'an section of the Weihe River by using high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS). The detection rates were 12.50–100%, and the detected concentrations were in the range of nd-270.60 ng/L. The average detected concentrations of the SAs, MLs, QNs, LIN and TC were 113.68, 111.79, 20.55, 23.81 and 25.66 ng/L, respectively. Among these, SAs and MLs were the dominant antibiotics detected in the Weihe River. Compared with those in other water bodies in China and abroad, the antibiotic residues in the Weihe River were at a moderate contamination level. The SAs concentration distribution followed upstream > midstream > downstream, while the MLs concentration distribution was midstream < downstream < upstream. The correlation analysis and principal component analysis (PCA) indicated that domestic sewage, livestock discharge, and aquaculture and pharmaceutical wastewater are the main sources of antibiotic residues in the Weihe River. In addition, the detected ciprofloxacin (CFX), ofloxacin (OFX) and sulfamethoxazole (SMX) pose high ecological risk in the short and long term.

In order to understand how darkness/irradiance and low nighttime temperature might alter physiology of Ulva prolifera under lower salinity conditions, we analyzed the growth rates, water content, superoxide dismutase (SOD) activity, total soluble proteins (SPs) and carbohydrates content at the end of dark and light period under three temperature levels (25–25 °C treatment: 25 °C for day and night; 15–15 °C treatment: 15 °C for day and night; 25–15 °C treatment: 25 °C for day with 15 °C for night) and two salinity conditions (15, 25), meanwhile, the pigment content (chlorophyll a and b), chlorophyll fluorescence and photosynthetic oxygen evolution also were determined during light phase. We found that the U. prolifera showed higher growth rate and SOD activity during dark phase at 25 °C, but this dark-induced increase could not be observed at 15 °C. The reasons for this increase varied, however, maybe not included water content and SPs for no significant difference in water content observed under all the treatments, as well as lower SPs content for dark period aside that at 15 °C and salinity 15. Compared to other two temperature treatments, the thalli grown at 25–15 °C showed higher growth rate and the photosynthetic oxygen evolution rate in light phase under salinity 15 conditions, although the maximum relative electron transport rate (rETRₘₐₓ) showed higher value under 25 °C treatment. These results indicate that the darkness and the lower nighttime temperature maybe responsible reason for the rapid growth of these green tide algae.

Shipping is key to global trade, but is also a dominant source of anthropogenic noise in the ocean. Chronic noise from ships can affect acoustic quality of important whale habitats. Noise from ships has been identified as one of three main stressors–in addition to contaminants, and lack of Chinook salmon prey–in the recovery of the endangered southern resident killer whale (SRKW) population. Managers recognize existing noise levels as a threat to the acoustical integrity of SRKW critical habitat. There is an urgent need to identify practical ways to reduce ocean noise given projected increases in shipping in the SRKW's summertime critical habitat in the Salish Sea. We reviewed the literature to provide a qualitative description of mitigation approaches. We use an existing ship source level dataset to quantify how some mitigation approaches could readily reduce noise levels by 3–10 dB.

Recent extreme hydrological events, such as high rainfall and storms, have been linked to climate change worldwide due to their relatively uncommon trends, which are generally described as having varying frequencies and higher intensities. Similar extreme rainfall trends were observed in the northwest Arabian Gulf during the 2018–2019 season. Heavy rainfall events have triggered high discharges in the river of Shatt Al-Arab, where, prior to these events, the discharge rate has exhibited a declining trend over the past 40 years. Shatt Al-Arab provides various physical, chemical, and biological functions in the region. In this study, some recent and extensive measurements of salinity and post-processed satellite images of chlorophyll-a in the northwest Arabian Gulf were recorded to assess the response of the region to the higher discharges. The results indicated that the salinity decreased significantly during and after the rainfall events in response to the higher discharges from Shatt Al-Arab. The effects of higher discharges extended over most of Kuwait's coastline, including Kuwait Bay. The chlorophyll-a distributions doubled after the extreme events, emphasising the effects of Shatt Al-Arab. Collectively, the results indicated that the discharge from Shatt Al-Arab during the extreme event exceeded 1400 m³/s, while, in the previous seasons, it rarely exceeded 80 m³/s. The higher discharge levels of discharge would result in various changes in ecology at multiple levels due to the sudden and reversing shift in the hydro-environmental processes.

Ocean acidification (OA) is well-known for impairing marine calcification; however, the end response of several essential species to this perturbation remains unknown. Decreased pH and saturation levels (Ω) of minerals under OA is projected to alter shell crystallography and thus to reduce shell mechanical properties. This study examined this hypothesis using a commercially important estuarine oyster Magallana hongkongensis. Although shell damage occurred on the outmost prismatic layer and the undying myostracum at decreased pH 7.6 and 7.3, the major foliated layer was relatively unharmed. Oysters maintained their shell hardness and stiffness through altered crystal unit orientation under pH 7.6 conditions. However, under the undersaturated conditions (ΩCal ~ 0.8) at pH 7.3, the realigned crystal units in foliated layer ultimately resulted in less stiff shells which indicated although estuarine oysters are mechanically resistant to unfavorable calcification conditions, extremely low pH condition is still a threat to this essential species.

Seismic surveys increasingly operate in deeper Arctic waters with propagation conditions and marine mammal fauna different from the better-studied temperate, or shallow-water, regions. Using 31 calibrated sound recorders, we quantified noise contributions from four concurrent seismic surveys in Baffin Bay, Greenland, to estimate their potential impacts on marine mammals. The impact was cumulative as the noise level rose in response to the onset of each survey: on a minute-by-minute scale the sound-exposure-levels varied by up to 70 dB (20 dB on average), depending on range to the seismic vessel, local bathymetry effects and interference patterns, representing a significant change in the auditory scene for marine mammals. Airgun pulse energy did not decrease to ambient before arrival of the next pulse leaving very little low-frequency masking-free time. Overall, the measured values matched well with pre-season-modeling, emphasizing the importance of noise-modeling in impact assessments, if responses of focal marine mammals are known.

Seagrasses are among the most threatened biomes worldwide. Until now, seagrass rehabilitation success has reached about 38% overall and more effective approaches to restoration are urgently needed. Here we report a novel method to rehabilitate Posidonia oceanica meadows based on observation of the species' natural recovery after disturbance. Posidonia oceanica rhizomes were transplanted on gabions filled with rocks of selected sizes in order to build a firm substrate with topographic complexity in the relevant scale range to propagules. Five techniques were tested, each involving a different anchoring device. The “slot” technique, which uses a wire-net pocket to retain the cuttings, was the most successful, with survival exceeding 85% after thirty months. Branching allowed final shoot survival to reach 422% of initial planting density. This study shows how an in-depth knowledge of species life history processes provides a suitable foundation for developing effective restoration methods that benefit from species recovery ability.

Metal history in a natural system was described since the early Holocene by analysing the preserved subsurface sediment record and present-day surface sediments. Normalized geochemical data from six sediment cores (129 samples) was compared with 28 surface samples. Pre-anthropic sedimentary environments allowed the definition of local natural Background Values. Enrichment Factors were then used for elements discrimination in terms of natural and anthropogenic inputs to the system. While subsurface results displayed a similar behaviour in all cores, pointing to largely undisturbed system, surface sediments show significant contamination, with high enrichment factors for As, Cu, Pb, and Zn. Other metal pollutants have generally low enrichment values, suggesting natural conditions. Surface results were reproduced as metal enrichment maps which evidenced anthropogenic sources in specific locations. This work reveals the importance of combining subsurface and surface geochemical data with mapping techniques in order to better evaluate the environmental quality of a natural system.

This study aims to reveal microplastic pollution. It is the first to be conducted in the South Aegean Region and one of the limited numbers of such studies in Turkey. To this aim, in September 2018 microplastic particles (MP's) pollution was evaluated on the sandy beaches along the coastline of the Datça Peninsula (Southern Aegean coast of Turkey) located at the intersection of the Aegean and Mediterranean Seas. MP's were analyzed using standard operating procedure along with some experimental techniques. Prior to the identification process, microplastics ranging from 1 to 5 mm were exposed to an experimental pre-treatment and efficient polymer scanning. The results showed that fragments (72%) were the dominant category from all the beaches exposed to dominant winds and surface currents and that MP contamination in the Datça Peninsula was higher than that reported in the literature from similar locations around the world (1154.4 ± 700.3 particles kg⁻¹ dw). More specifically the highest contamination was found in Aktur Beach (2073.3 ± 648.6 particles kg⁻¹ dw) which could be considered as a hotspot for the whole region in terms of MP pollution. As a result of the study, as sampling stations are remote from major cities and industrial zones, maritime activities increase during summer season and tar has been observed on particles during analyses, it can be asserted that the pollution may be caused by marine resources.