Effects of Reservoir Mainstream on Longitudinal Zonation in Reservoir Bays

Spatial longitudinal zonation in reservoir bays is poorly documented, and most published papers considered that longitudinal zonation in bays is similar to that in reservoirs. Our results from analyses of the benthic macroinvertebrate community in the bays of the Three-Gorges Reservoir, China, showed that a typical bay contains four distinct zones-one more zones than a reservoir. This newly distinguished zone lies along the mouth stretch of a reservoir bay, and we call it a mainstream zone because it is disturbed by the reservoir mainstream. The mainstream zone is characterized by a lower standing crop and a more unstable macroinvertebrate community than in the lacustrine zone. Longitudinal zonation of reservoir bays is related to their lengths, and lacustrine zones develop only where the bay is sufficiently long. Similar to reservoirs, longitudinal zonation in bays is also dynamic and is to some extent influenced by the ages of bays and seasons

Developing a Benthic Index of Biological Integrity and Some Relationships to Environmental Factors in the Subtropical Xiangxi River, China

The aim of this study is to develop a benthic index of biotic integrity (B-IBI) to help understand how the increasing anthropogenic pressure may impact the subtropical Xiangxi River in China. Benthic macroinvertebrate and environmental surveys were conducted at 77 sites in early summer 2004. Each collection site was categorized as reference or impaired based on physical, chemical, biological, and land-use information. Six non-redundant metrics from 35 metrics were used to differentiate between reference and impaired sites. We selected six metrics for the final IBI. The scoring criteria of each metric were normalized based on the quadrisection and 0-10 scaling systems. Both scaling methods were used to assess the aquatic health of each site in the Xiangxi River watershed. The results showed that most sites were in fairly poor condition. Furthermore, we identified the relationship between B-IBI metrics, water-quality, and land-use variables with a principal component analysis. A composite of nutrients and land-use intensity explained most variances. These results suggest that the B-IBI may be a suitable method for assessing river conditions within the subtropical Xiangxi River in central China

Seasonal dynamics of suspended solids in a giant subtropical reservoir (China) in relation to internal processes and hydrological features

To explore the factors regulating seasonal variation of total suspended solids (TSS) and its two fractions in a giant dendritic reservoir (the Three-Gorges Reservoir of China, TGR) in the subtropical monsoon region, suspended solids, chlorophyll a (a surrogate for lake internal processes) and water residence time (an index of hydrologic flushing) were examined monthly from August 2005 to July 2006. TSS ranged from 0.6 to 200.3 mg/L and from 0.6 to 78 mg/L respectively in the mainstream and in a typical reservoir-bay (the Xiangxi Bay) of the TGR,. TSS exhibited a typical seasonal pattern in the mainstream rather than in the Xiangxi Bay of the TGR. The fraction of non-volatile suspended solids (NVSS) was often more dominant in the mainstream than in the Xiangxi Bay, especially during the flood season. Regressions analysis showed that 87.6% and 89.8% of seasonal variation in TSS and NVSS of the mainstream, respectively, are explained by water residence time. In contrast, suspended solids (particularly volatile suspended solids, VSS) of the Xiangxi Bay displayed significant correlation with algal biomass, and no correlation with hydrological parameters. It implies that the Xiangxi Bay was a more autochthonous system than the mainstream of the TGR where exogenous influences were the more determinant factors. (C) 2009 Elsevier Ltd and INQUA. All rights reserved

Diel vertical migration of Peridiniopsis niei, Liu et al., a new species of dinoflagellates in an eutrophic bay of Three-Gorge Reservoir, China

In spring, a typical dinoflagellate (Peridiniopsis niei Liu et al.) constitutes most of the phytoplankton biomass in most of eutrophic bay of Three-Gorge Reservoir (TGR, China). There are few field observations on vertical migration of the members of the genus Peridiniopsis. We studied diel vertical migration of the new species (Peridiniopsis niei) at sampling stations A and B in an eutrophic bay (Xiangxi Bay) of TGR during both day and night in March 2007. The present study suggests that vertical migration by Peridiniopsis niei is similar in nature to the migration patterns observed for other dinoflagellates. Solar irradiance incident was an important factor regulating the ascent and descent of Peridiniopsis niei. The vertical descent of Peridiniopsis niei during nighttime was restricted when the thermocline (Temperature gradient > 1A degrees C m(-1)) was present in the station B

New Trends in Environmental Engineering, Agriculture, Food Production, and Analysis

This Special Issue presents the latest advances in agriculture, aquaculture, food technology and environmental protection and engineering, discussing, among others, the following issues: new technologies in water, stormwater and wastewater treatment; water saving, lake restoration; new sludge and waste management systems; biodiesel production from animal fat waste; the microbiological quality of compound fish feeds for aquaculture; the role of technological processes to improve food quality and safety; new trends in the analysis of food and food components including in vitro, in vivo, and in silico analyses; and functional and structural aspects of bioactivities of food molecules

Spring phytoplankton blooms in Xiangxi Bay of Three-Gorges Reservoir: spatiotemporal dynamics across sharp nutrient gradients

After the impoundment of Three-Gorges Reservoir, the specific hydrodynamics created sharp nutrient gradients in Xiangxi Bay. To discover how spring blooms in Xiangxi Bay respond to sharp nutrient gradients, we investigated the phytoplankton community composition and dynamics along nutrient gradients and analyzed the strategies of different types of phytoplankton in filling their niches. We observed a total of 148 taxa of 59 genera belonging to seven phyla. Phytoplankton concentration ranged from 0.03 x 10(7) to 3.74 x 10(7) cell L-1 with two pulses during the spring bloom period. Bacillariophyta was the predominant group, which accounted for 75.4% of total abundance. Canonical correlation analysis (CCA) revealed that phytoplankton occurred in optimal niches for their growth across the nutrient gradients. Specifically, species of Bacillariophyta were found in the region with Si:DIN > 1, and species of Cryptophyta, Chrysophyta, Euglenphyta, Pyrrophyta, and some of Chlorophyta were most abundant in the region with DIN:PO4P < 16. High abundances of Cyanophyta and some Chlorophyta were observed in the region where DIN:PO4P > 16. The CCA also indicated a potential nutrient limitation of Si on Bacillariophyta, of DIN on Cyanophyta and some Chlorophyta, and of PO4P on Cryptophyta, Euglenphyta, Pyrrophyta, and some Chlorophyta. Moreover, as a complement for the traditional Redfield ratio of 16N:1P in determining whether N or P limits a system, our study revealed that the stoichiometric ratio of 1Si:1DIN is an important criterion to determine limitation for diatoms

Descriptions of two new Cephalaeschna species from Yunnan, China (Odonata: Aeshnidae)

Two new species, Cephalaeschna cornifrons sp. nov. and C. ordopapiliones sp. nov. from Yunnan Province, China, are described, illustrated in color and compared with known Chinese Cephalaeschna. All the holotypes are deposited in the Collection of Aquatic Animals, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan City, Hubei Province, China. Brief notes on biology of each species are also provided.Two new species, Cephalaeschna cornifrons sp. nov. and C. ordopapiliones sp. nov. from Yunnan Province, China, are described, illustrated in color and compared with known Chinese Cephalaeschna. All the holotypes are deposited in the Collection of Aquatic Animals, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan City, Hubei Province, China. Brief notes on biology of each species are also provided

Daily dynamics of nutrients and chlorophyll a during a spring phytoplankton bloom in Xiangxi Bay of the Three Gorges Reservoir

We studied the daily dynamics of nutrients (total phosphorus [TP], total nitrogen [TN], and dissolved silicate [SiO2]) and chlorophyll a (chl a) during a spring bloom in Xiangxi Bay of the Three Gorges Reservoir in year 2005. According to the daily dynamics of chl a, the bloom occurred in two stages (23 February-25 March and 26 March-28 April). The concentration of SiO2 decreased at different layers of the water column with the development of the bloom. However, the decrease of SiO2 in the layers with high concentration of chl a was more dramatic than in the layers with low concentration of chl a. The concentration of TP was lowest value a few days after the peak of chl a during the first bloom period, and the lowest value of TN was found a few days after the peak of chl a during the second bloom period. Correlative analyses indicated that SiO2 and TP were limiting factors in the first bloom period, and SiO2 and TN were limiting factors in the second bloom period.We studied the daily dynamics of nutrients (total phosphorus [TP], total nitrogen [TN], and dissolved silicate [SiO2]) and chlorophyll a (chl a) during a spring bloom in Xiangxi Bay of the Three Gorges Reservoir in year 2005. According to the daily dynamics of chl a, the bloom occurred in two stages (23 February-25 March and 26 March-28 April). The concentration of SiO2 decreased at different layers of the water column with the development of the bloom. However, the decrease of SiO2 in the layers with high concentration of chl a was more dramatic than in the layers with low concentration of chl a. The concentration of TP was lowest value a few days after the peak of chl a during the first bloom period, and the lowest value of TN was found a few days after the peak of chl a during the second bloom period. Correlative analyses indicated that SiO2 and TP were limiting factors in the first bloom period, and SiO2 and TN were limiting factors in the second bloom period

Recent advances in allelopathy (Vol. 1)

The discovery of new allelochemicals from plants and microbes has attracted our attention in the last 20 years due to their ecological implications as biocommunicators in nature and to their potential use as a source of new structural types of agrochemicals. Recent Advances in Aiieiopathyis a new triennial scientific series which has been born with the aim of collecting whatever can be considered relevant in the field of Allelopathy research within a period of three years, considering every aspect of this multidisciplinary science. This first volume A Science for the Future presents a selected number of chapters in which internationally renowned experts discuss how a better understanding of allelochemical phenomena can lead to natural applications. Ifwe know the way thatplants madepossible theirinter- andintraspecific relationship within a specific ecosystem, we can mimic certain processes and think in applications as natural herbicides, antibiotics, fungicides, natural insecticides, etc. This book is divided into four sections: I) Methodology and Techniques in Allelopathic Studies. II) Chemistry, Physiology and MechanismofAllelopathic Processes. Ill) Allelopathic Interactions in Nature. IV) Allelopathy in Weed and Plant Disease Control. It presents an overview of the different fields involved in Allelopathy in an integrated way. We hope that this book will help, both those people that read for the first time about Allelopathy and those that have been working for a hard long time in the research and development of Allelopathy, get enthusiastic about Allelopathy