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In order to identify a potential surrogate of planktonic ciliate communities for marine bioassessments and evaluating biological conservations, the different taxonomic/numerical resolutions and taxa as surrogates were studied in Jiaozhou Bay, northern China during a 1-year cycle (June 2007-May 2008).Samples were collected biweekly from a depth of 1 m at each of five sites. A range of physicochemical parameters were also measured in order to determine water quality.The genus- and family-level resolutions maintained sufficient information to evaluate the ecological patterns of the ciliate communities in response to environmental status. The non-loricate oligotrichous ciliate assemblages in both abundance and occurrence may be used as a surrogate of planktonic ciliate communities. Heavy data transformations were an optimal strategy for the species level of planktonic ciliates, while mild data transformations were for the higher. The ordination patterns based on species biomass, occurrence, and biomass/abundance ratio matrices were significantly consistent with that of species abundance data.The results suggest that the use of simplifications at both taxonomic and numerical resolutions are time-efficient and would allow improving sampling strategies of large spatial/temporal scale monitoring programs and biological conservation researches in the marine ecosystem with a relative paucity of scientists.

The offshore wells are subject to hostile environments of such areas as the North Sea, GOM and the high arctic. The strong loop ocean currents and induced eddies can pose significant problems for deep-water well. Broadly divided ocean currents, surface currents, bottom currents and vertical currents, interact with the deep water well structures as one of environmental forces. One of the engineering challenges in deep water drilling is temperature gradient. In the past the temperature in the wellbore was ignored and an isothermal system was assumed because no practical means existed to determine the well bore temperature profile. But the fact is that the negative thermal gradient exists between surface to seafloor and it becomes positive below the seafloor. The extreme values could be as low as 40°F and as high as 150∼200°F. In addition to low temperature condition, the significant heat exchange also occurs for high temperature and geothermal reservoirs. The universal matrix form of implicit finite differential equations is introduced to predict the temperature profile of the fluid in the well and near-wellbore formation. This paper is to combine various factors together to derive a solver for the transient temperature modeling during the dirculation of riserless drilling, which can be the basis to describe the near-wellbore well stability under geo-thermal stress and predict the annular pressure during HPHT injection or production, which can also be used to including but not limited to the dynamic temperature profile and bottom-hole temperature, improving cementing program design, casing thermal stresses to be determined.

Abstract Marine gas hydrates mostly occur in high-water content and non-diagenetic submarine sediments without tight stratigraphic traps. Therefore, the seepage capability of overlying and underlying strata (OUS) serves as a crucial parameter to analyze hydrate production behaviors. This study focuses on the numerical simulation study on the effects of the seepage capability of OUS on hydrate production behaviors in depressurization-induced production of three-phase hydrate deposits using a horizontal well. As shown by the simulation results, in the early stage of hydrate production, the permeability of the OUS had little effects on gas production rates. In long-term hydrate production, the hydrate deposit with lower permeability OUS has higher cumulative gas production, larger gas-water ratio and hydrate dissociation scope, and less cumulative water production. Moreover, the hydrate production efficiency first decreased rapidly and then tended to be stable as the permeability of OUS increased, and hydrate production behaviors are similar while the permeability of OUS larger than 1.0 mD. Herein, a water-resisting layers were constructed in overlying and/or underlying strata to decrease the seepage capability of OUS. Compared to the original hydrate deposits, the cumulative gas production and gas-water ratio increased by 31% and 147%, respectively but the water production was only 76% on the 5th year of the simulated production in which water-resisting layers were designed. Furthermore, the water-resisting layer in underlying strata produced more significant effects on hydrate production efficiency than the layer in overlying strata. All these indicate that the low-permeability OUS (especially in underlying strata) can restrain fluid invading into hydrate reservoirs, increase the pressure gradient of hydrate reservoirs and significantly improve the hydrate production efficiency during long-term hydrate production. Therefore, water-proof reformation in OUS may be an effective method to improve the energy utilization efficiency and promote the process of hydrate industrialization. However, further research is needed.

Climate change-induced glacial melting is a global phenomenon. The effects of climate change-induced melting on the microbial ecology in different glacial-fed aquatic systems have been well illuminated, but the resolution of seasonal dynamics was still limited. Here, we studied bacterial community composition and diversity in a glacial-fed Tibetan lake, Lake Ranwu, to elucidate how glacial-fed aquatic ecosystems respond to the seasonal glacial melting. Obvious seasonal variations of bacterial dominant groups were found in Lake Ranwu and inlet rivers. In April, the majority of OTUs belonged to the Bacteroidetes, Actinobacteria and Proteobacteria. The Proteobacteria increased to the most abundant phylum in July and November, while the Bacteroidetes and Actinobacteria decreased about 50% over seasons. Most key discriminant taxa of each season's community strongly associated with specific environmental variables, suggesting their adaptation to seasonal environments. Bacterial alpha diversity varied among seasons and exhibited strongly negative correlations with conductivity. Conductivity was the major driving force in determining the seasonal variation of bacterial community composition. Fluctuated conductivity was one of the consequences of seasonal melting of glaciers. This study offered evidence for the unique seasonal dynamics pattern of bacterial communities responding to glacial melting. Moreover, this study may provide a reference for assessing the long-term effects of glacial retreat on glacial-fed aquatic ecosystems.

Diatoms, with their complex cellular architecture, have been recognized as a source of limitless potential. These microbes are common in freshwater and marine habitats and are essential for primary production and carbon sequestration. They are excellent at utilizing nutrients, providing a sustainable method of treating wastewater while also producing biomass rich in beneficial substances like vitamins, carotenoids, polysaccharides, lipids, omega-3 fatty acids, pigments, and novel bioactive molecules. Additionally, they are highly efficient organisms that can be employed to monitor the environment by acting as trustworthy indicators of water quality. This comprehensive review explores the multifaceted applications of diatoms in a variety of fields, such as bioremediation, aquaculture, value-added products, and other applications. The review set out on a path towards greener, more sustainable methods amicable to both industry and the environment by utilizing theenormous diverse biotechnological potentials of diatoms.

Estuarine and tidal wetlands with high primary productivity and biological activity play a crucial role in coastal nutrient dynamics. Here, to better reveal the effects of extracellular enzymes and microbial community on carbon (C) and nitrogen (N) mineralization, the incubation experiments with different C and N addition patterns to the tidal sediments of the Yangtze Estuary (China) were conducted. The results suggested a significant increase in cumulative CO2 effluxes in the C and CN treatment experiments, while no significant difference in cumulative CO2 effluxes between the N treatment and control (CK) experiments was observed. In addition, the nutrient addition patterns had a great influence on dissolve organic C and N levels, but a small effect on microbial biomass C and N. Microbial community composition and microbial activity were found to be positively correlated with organic C (OC) and the molar ratio of C to N (C/N). Partial correlation analysis, controlling for C/N, supported direct effects of OC on the activity of carbon-cycling extracellular enzymes (cellulase and polyphenol oxidase), while C/N exhibited negatively correlations with urease and Gram-positive bacteria to Gram-negative bacteria (G+/G-). Strong relationships were found between CO2 efflux and mineral nitrogen with the activity of specific enzymes (sucrase, cellulase, and polyphenol oxidase) and abundances of Gram-negative bacteria, arbuscular mycorrhizal fungi, and fungi, suggesting the significant influences of microbial community and enzyme activity on C and N mineralization in the estuarine and tidal wetlands. Furthermore, this study could highlight the need to explore effects of nutrient supply on microbial communities and enzyme activity changes associated with the C and N mineralization in these wetlands induced by the climate change.

Water crises have been among the most serious environmental problems worldwide since the twenty-first century. A water crisis is marked by a severe shortage of water resources and deteriorating water quality. As an important component of water resources, lake water quality has deteriorated rapidly in the context of fast urbanization and climate change. This deterioration has altered the water ecosystem structure and influenced lake functionality. To curb these trends, various strategies and procedures have been used in many urban lakes. Among these procedures, accurate and responsive water environment monitoring is the basis of the forecasting and prevention of large-scale cyanobacteria outbreaks and improvement of water quality. To dynamically monitor and predict the outbreak of cyanobacteria in Dianchi Lake, in this study, wireless sensors networks (WSNs) and the geographic information system (GIS) are used to monitor water quality at the macro-scale and meso-scale. Historical, real-time water quality and weather condition data were collected, and a combination prediction model (adaptive grey model (AGM) and back propagation artificial neural network (BPANN)) was proposed. The correlation coefficient (R) of the simulation experiment reached 0.995. Moreover, we conducted an empirical experiment in Dianchi Lake, Yunnan, China using the proposed method. R was 0.93, and the predicting error was 4.77. The results of the experiment suggest that our model has good performance for water quality prediction and can forecast cyanobacteria outbreaks. This system provides responsive forewarning and data support for lake protection and pollution control.

Enrichment of waterways with nitrogen (N) and phosphorus (P) has accelerated eutrophication and promoted cyanobacterial blooms worldwide. An understanding of whether cyanobacteria maintain their dominance under accelerated eutrophication will help predict trends and provide rational control measures. A mesocosm experiment was conducted under natural light and temperature conditions in Lake Taihu, China. It revealed that only N added to lake water promoted growth of colonial and filamentous cyanobacteria (Microcystis, Pseudoanabaena and Planktothrix) and single-cell green algae (Cosmarium, Chlorella, and Scenedesmus). Adding P alone promoted neither cyanobacteria nor green algae significantly. N plus P additions promoted cyanobacteria and green algae growth greatly. The higher growth rates of green algae vs. cyanobacteria in N plus P additions resulted in the biomass of green algae exceeding that of cyanobacteria. This indicates that further enrichment with N plus P in eutrophic water will enhance green algae over cyanobacterial dominance. However, it does not mean that eutrophication problems will cease. On the contrary, the risk will increase due to increasing total phytoplankton biomass.