Age, growth, mortality and movement patterns of shortjaw tapertail anchovy, Coilia brachygnathus, in the channel connecting Dongting Lake and the Yangtze River in central China

Shortjaw tapertail anchovy, Coilia brachygnathus, is one of the anchovy species that exclusively lives in freshwaters, which is the dominant species in Dongting Lake. In order to explain its success as a dominant species in Dongting Lake, the basic biological knowledge of this species was studied from July 2013 to July 2015 in the channel connecting Dongting Lake and the Yangtze River. A total of 11 064 samples of C. brachygnathus were collected, and their standard length ranged between 6.8 and 35.4 cm. The length–weight relationship was W = 0.0026 L3.057, and von Bertalanffy growth curve was Lt = 36.41(1 − e−0.28(t+0.8)). The exploitation rate (E) of 0.49, indicated no overfishing on this species. Its movement patterns were highly significantly and positively correlated with the rate of variation in water level, discharge and water temperature. When water level (discharge and temperatures) were rising (mainly March to July), C. brachygnathus migrated into Dongting Lake, peaking in May. When the water level (discharge and temperatures) were falling (mainly October to December), the migratory behaviour changed to exiting Dongting Lake, peaking in October. The present study suggests, fast generation time, low exploitation rate and the river–lake movements (migrations) are the possible reasons that made C. brachygnathus a dominant species in this area

Lateral migration of fish between China's second largest freshwater lake (Dongting Lake) and the mainstem of the Yangtze River

Lateral migration of fish between Dongting Lake and the mainstem of Yangtze River was investigated at the channel connecting these two systems to identify its regular pattern and possible affecting factors. During the sampling period, a total of 55 fish species were recorded, with the lake-river migratory fish species dominating abundance all the time. Hierarchical clustering analysis found four temporal fish assemblages: Feb-Mar, Apr-Jun, Jul-Sep and Oct-Jan, which was consistent with the rising and falling of water temperature and water level. The Movement index was used to measure the direction of fish migration, which was found closely associated with variations of water temperature, water level and flow discharge. Particularly, when water temperature and water level rose from March to July, fish migration showed the tendency of entering the lake; when they receded from August to February of the next year, fish migration showed the opposite tendency. Based on our results, we concluded that maintaining the river-lake connection is essential for the river-lake migratory fishes and the natural flow regime was the key driver in this floodplain ecosystem

Ichthyoplankton recruitment from mainstream of the Changjiang River into the Dongting Lake, the second largest freshwater lake in China

Floodplains are important and distinctive ecosystems around the world, and the recruitment of ichthyoplankton from river to floodplain lakes is crucial to maintain this unique ecosystem. However, this process has not been well documented. In this study, ichthyoplankton were sampled to investigate the details of ichthyoplankton recruitment from the Changjiang (Yangtze) River to the Dongting Lake via a floodway channel, the Songzi River, from May to July in 2013 and 2014. During the study period, 41 species of eggs and larvae were sampled. Among the samples, 16 were river-lake migratory species (RL), representing 23.5% of the species in the Dongting Lake. In 2013, an estimated 130 million eggs and 3 180 million larvae drifted through the sampling section, and in 2014, an estimated 1 060 million eggs and 1 040 million larvae drifted through the sampling section. The amount of eggs and larvae of RL reached 3 210 million in 2013 and 1 850 million in 2014, respectively. These results demonstrated the importance of ichthyoplankton recruitment from the river to the lake, as species diversity' will decrease sharply without this recruitment. Canonical correspondence analysis (CCA) showed that water temperature and water flow are the two most important factors influencing the spawning activities of fish. To maintain the high fish diversity in the Changjiang floodplain, we suggest to irrigate the channel to increase water discharge and increase the transport of ichthyoplankton from the Changjiang mainstream into the Dongting Lake

Age, growth, mortality and movement patterns of shortjaw tapertail anchovy, Coilia brachygnathus, in the channel connecting Dongting Lake and the Yangtze River in central China

Shortjaw tapertail anchovy, Coilia brachygnathus, is one of the anchovy species that exclusively lives in freshwaters, which is the dominant species in Dongting Lake. In order to explain its success as a dominant species in Dongting Lake, the basic biological knowledge of this species was studied from July 2013 to July 2015 in the channel connecting Dongting Lake and the Yangtze River. A total of 11 064 samples of C. brachygnathus were collected, and their standard length ranged between 6.8 and 35.4 cm. The length-weight relationship was W= 0.0026 L-3.057, and von Bertalanffy growth curve was L-t = 36.41(1-e(-0.28(t+0.8))).The exploitation rate (E) of 0.49, indicated no overfishing on this species. Its movement patterns were highly significantly and positively correlated with the rate of variation in water level, discharge and water temperature. When water level (discharge and temperatures) were rising (mainly March to July), C. brachygnathus migrated into Dongting Lake, peaking in May. When the water level (discharge and temperatures) were falling (mainly October to December), the migratory behaviour changed to exiting Dongting Lake, peaking in October. The present study suggests, fast generation time, low exploitation rate and the river-lake movements (migrations) are the possible reasons that made C. brachygnathus a dominant species in this area

Age, growth, mortality and movement patterns of shortjaw tapertail anchovy,

Shortjaw tapertail anchovy, Coilia brachygnathus, is one of the anchovy species that exclusively lives in freshwaters, which is the dominant species in Dongting Lake. In order to explain its success as a dominant species in Dongting Lake, the basic biological knowledge of this species was studied from July 2013 to July 2015 in the channel connecting Dongting Lake and the Yangtze River. A total of 11 064 samples of C. brachygnathus were collected, and their standard length ranged between 6.8 and 35.4 cm. The length–weight relationship was W = 0.0026 L3.057, and von Bertalanffy growth curve was Lt = 36.41(1 − e−0.28(t+0.8)). The exploitation rate (E) of 0.49, indicated no overfishing on this species. Its movement patterns were highly significantly and positively correlated with the rate of variation in water level, discharge and water temperature. When water level (discharge and temperatures) were rising (mainly March to July), C. brachygnathus migrated into Dongting Lake, peaking in May. When the water level (discharge and temperatures) were falling (mainly October to December), the migratory behaviour changed to exiting Dongting Lake, peaking in October. The present study suggests, fast generation time, low exploitation rate and the river–lake movements (migrations) are the possible reasons that made C. brachygnathus a dominant species in this area

A Reliable Method of Minimum Zone Evaluation of Cylindricity and Conicity from Coordinate Measurement Data

The form error evaluation of cylinders and cones is very important in precision coordinate metrology. The solution of the traditional least squares technique is prone to over-estimation, as a result unnecessary rejections may be caused. This paper proposes a reliable algorithm to calculate the minimum zone form errors of cylinders and cones, called a hybrid particle swarm optimization-differential evolution algorithm. The optimization is conducted in two stages, so that the program can hold a fast convergence rate, while effectively avoiding local minima. Experimental results demonstrate that the proposed algorithm can obtain very accurate and stable results for the calculation of cylindricity and conicity

Ag₆Si₂O₇: a Silicate Photocatalyst for the Visible Region

Ag₆Si₂O₇: a Silicate Photocatalyst for the Visible Regio