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.

Akashiwo sanguinea is a harmful—but not toxic—species that causes blooms around the world. In China, the first A. sanguinea bloom was recorded in Yantai in 1998. Until 2017, there were 31 occurrences of A. sanguinea blooms recorded in Chinese four seas, with large spatial distributions. Furthermore, these blooms were recorded in almost every month except November, December and January. It can be concluded that the 1990s represented the initial stage of A. sanguinea blooms, while the 2000s represented the spreading stage and the 2010s represented the burst stage in China.

The aim of this research was to assess the impact of hydrotechnical works within the riverbed and riparian zone on the mobility of mercury in soil and its outflow to the river and the sea. Deepening and reconstruction of the riverbed or the cutting of reeds, influenced the fate of mercury in the river system. However, only activitis that disturbed the riperian zone increased mobilization of Hg in soils. Hg transformations in these places were controled by inflow of fresh organic matter in soil and sediments as well as by oxidation-reduction potential. In areas where reducing conditions occurred, mercury released from the soil was incorporated into the sediment. However, in areas where oxidizing conditions prevailed in the sediment, mercury flowing out of the soil occurred mainly in dissolved form and most of it was transported downstream from where it could reach the sea.

Increasing evidence shows that herbivores can facilitate plant growth and maintain the resistance of plant communities to trophic consumption in a variety of ecosystems. However, the positive effects of herbivores on annual saltmarsh plants in coastal ecosystems are relatively understudied. In this study, field investigations and manipulative experiments were conducted to explore whether and how microtopographical modification by the herbivorous crab Helice tientsinensis stimulates the growth of the saltmarsh plant Suaeda salsa. Results showed that, despite grazing on S. salsa, H. tientsinensis can promote density, total biomass, average plant height, average root length, and average biomass through burrowing-generated concave-convex microtopography, which can improve the edaphic environment (decreased soil hardness and salinity, and increased soil moisture content, oxidation-reduction potential, and carbon and nitrogen content), and provide plants more clustered growth opportunities that could facilitate positive intraspecific plant interactions. This study can provide scientific guidance for ecosystem restoration in coastal intertidal saltmarshes.

Argonauta nouryi Lorois, 1852 is an octopod that inhabits the holopelagic zone, the objective of this study was to describe the occurrence of buoyant fibers adhering to the body and mantle cavity of A. nouryi females found in the stomach contents from Euthynnus lineatus (skipjack), Coryphaena hippurus (dolphinfish), and Istiophorus platypterus (sailfish). Stomach contents from 224 individuals were examined. All female evaluated presented fibers adhering to the mantle cavity; 92.6% of the fibers measured 0.25 to 5 mm in length and hyaline was the dominant color (72%). The amount of fibers in the fish stomach contents with A. nouryi was significantly greater than in stomachs without; this suggests that the fibers might be introduced via A. nouryi. Findings of this work could be related to the discharge of solid materials in the water column.

Within tropical environments, short-term impacts of increased seawater temperature and pCO₂ on algae-herbivore interactions remain poorly understood. We investigated the isolated and combined 7-day effects of increased temperature (+4 °C) and pCO₂ (~1000 μatm) on the trophic interaction Ulva sp./Trochus histrio, by assessing: i) topshells’ survival and condition index; ii) grazer consumption rates, nutritional composition and interaction strength expressed as a dynamic index. No survival differences were observed whilst body condition varied significantly. Topshells under high pCO₂ displayed poor performance, concomitant with lower consumption of macroalgae. Individuals exposed to increased temperature had better physical condition, thus stimulating herbivory, which in turn was negatively correlated with carbon and nitrogen contents. The dynamic index was temperature- and pCO₂- interactively dependent, suggesting lower grazing pressure under single acidification. Despite some limitations inherent to a short-term exposure, this study provides new insights to accurately predict tropical species' phenotypic responses in a changing ocean.

In the current study, ecological risk of potentially toxic elements (PTEs) in sediments, seawater, wastewater, soft tissues and shell of a major fouling species Callista florida (C. florida) and soft tissue of rocky oyster, Saccostrea cucullata (S. cucullata) are investigated. For this purpose, 25 sediment samples, 24 seawater samples, 28 wastewater samples, and 100 bivalve samples were collected for PTEs analysis. Risk index (RI) and sediment quality guidelines along with calculated enrichment factors (EF) and PTEs profiles revealed that Musa Estuary is threatened by contamination, especially with respect to Hg, Cu, and Zn. The decreasing trend of average element enrichment factor is: Hg > Cu > Ni > Cd > Zn > Co > Cr > Mn > Fe > As > Pb > Mo > Sb. Among the investigated elements, Hg indicated the highest potential ecological risk factor in sediment (RI and EF are 1341.6 and 214.66 close to the industrial area). The Ficklin chart results demonstrated that seawater samples almost plot in regions with high metal load and pH values were the same. Mean concentrations of PTEs in water samples were 1.2 (for Cu) to 6565 (for Hg) times higher than world seawater. Regarding wastewater, pH values changed from very acidic to alkaline while PTEs load ranged from low to high load. In general, PTEs concentration in water samples was higher compared to those of the world seawater. Based on the results obtained in this biomonitoring study, elevated concentrations of Al, Fe, Cu, and Zn were found in soft tissue of C. florida and S. cucullata. Statistical analysis revealed significant differences in PTEs concentration between the two studied species. Generally, most PTEs concentration including Al, Co, Cr, Fe, Mn, Ni, Pb, and Sb in soft tissue fall between water and sediment samples i.e., sediment > biota > water.

Anthropogenic noise can have a negative effect on the physiology and survival of marine fishes. Most research has focused on later life-stages, and few studies have investigated the effects of human-induced noise on embryogenesis. The current study investigated whether playback of motorboat noise affected the embryogenesis of the coral reef damselfishes, Amphiprion melanopus and Acanthochromis polyacanthus. Embryos reared under the playback of boat noise had faster heart rates compared to the ambient reef controls. The effects of noise on morphological development differed between species and the fundamental interrelationships between early life history characteristics changed dramatically under boat noise for Ac. polyacanthus. Noise treatments did not alter the survival rates of embryos under laboratory conditions. Although species specific, our findings suggest that anthropogenic noise causes physiological responses in fishes during embryogenesis and these changes have direct impacts on their development and these alterations may have carry-over effects to later life stages.

To explore the effects of coastal eutrophication and warming on phytoplankton biomass and cell size, we analyzed current and historical data for size-fractionated chlorophyll a (chla) in Xiangshan Bay, China. Results showed that micro- and nanophytoplankton overwhelmingly dominated (>84%) in all seasons. The contribution of micro-chla was significantly lower in warm than in cold seasons, whereas contribution of pico-chla showed the opposite result. Overall, the micro-chla contribution increased with decreasing pico-chla contribution from the stable, clear, eutrophic upper bay to the turbulent, turbid lower bay, indicating that phytoplankton size structure on a spatial scale was largely shaped by water column stability and light rather than by nutrients. Since the 1980s, phytoplankton biomass, primary productivity, and micro-chla contribution in Xiangshan Bay have increased sharply with increasing nutrient amounts and temperature. Additionally, it seems that algal bloom seasonality has shifted forward from spring to winter since the power plant operations in 2006.

Integrated rice-shrimp ponds (IRSPs) have periods of low oxygen and high nutrient loads which may have a critical effect on both shrimp survival and water quality in adjacent waterways. To understand drivers of poor water quality, this study examined sediment nutrient pathways at two IRSPs. The study showed that the IRSPs had low denitrification efficiency. However, denitrification rates were significantly positively correlated with chlorophyll a concentrations, suggesting carbon availability was a key driver of denitrification. Dissolved nutrient concentrations in the water column were relatively high despite low sediment nutrient effluxes. Given the low sediment nutrient effluxes, and low nitrogen (N) removal by denitrification, the high nutrient loads were likely derived from incoming water. Therefore, the IRSPs were net nutrient removal mechanisms, rather than contributing to eutrophication in adjacent waterways. There also appears to be scope to enhance denitrification for increased N removal, via carbon addition, and hence improve water quality.