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Wang S.-P.,Harbin Engineering University | Chu W.-H.,Shanghai Ocean University | Chu W.-H.,Collaborative Innovation Center for Distant Water Fisheries | Zhang A.,Harbin Engineering University
China Ocean Engineering

The pulse features of a bubble have a close connection with the boundary condition. When a bubble moves near a rigid wall, it will be attracted by the Bjerknes force of the wall, and a jet pointing at the wall will be generated. In real application, the bubble may move under the combined action of walls in different directions when it forms at the corner of a pipe or at the bottom of a dam. The motion of the bubble shows complex and nonlinear characteristics under these conditions. In order to investigate the bubble pulse features near complex walls, a horizontal wall and a vertical wall are put into the experimental water tank synchronously, and an electric circuit with 200 voltages is designed to generate discharge bubbles, and then experimental study on the bubble pulse features under the combined action of horizontal and vertical walls is carried out. The influences of the combined action of two walls on the bubble shape, pulse period, moving trace and inside jet are obtained by changing the distances from bubble center to the two walls. It aims at providing references for the relevant theoretical and numerical research. © 2014 Chinese Ocean Engineering Society and Springer-Verlag Berlin Heidelberg. Source

Liu B.L.,Shanghai Ocean University | Liu B.L.,The Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources | Liu B.L.,Collaborative Innovation Center for Distant Water Fisheries | Liu B.L.,University of Maine, United States | And 4 more authors.
Fisheries Oceanography

Signatures of trace elements and isotopes in the parts of hard structures formed in the early ontogenetic stages can be used as potential natural tags of adult cephalopods to trace their origins. The Jumbo flying squid, Dosidicus gigas, is widely distributed in the eastern Pacific Ocean. Fourteen detected elemental signatures (7Li, 23Na, 24Mg, 39K, 43Ca 55Mn, 59Co, 60Ni, 63Cu, 66Zn, 88Sr, 137Ba, 208Pb and 238U) were determined in the nuclear zone (N), representing the embryonic stage, and the postnuclear zone (PN), representing the paralarval stage of statoliths for adult D. gigas collected off the Costa Rican, Peruvian and Chilean Exclusive Economic Zones (EEZs) using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). All measured signatures were significantly different between embryonic and paralarval statoliths, except for Sr, Ba and Pb. Over the three regions, a significant difference was found for Na and Ba within embryonic statoliths and Zn and Ba within paralarval statoliths. A high Ba/Ca ratio in statoliths obtained from Costa Rica was because of the prevalence of strong upwelling in the area. Elemental signatures, especially Ba/Ca, in early ontogenetic statoliths could be used as a proxy for distinguishing different geographical groups and identifying natal origins. However, elemental signatures in embryonic statoliths tended to be a better natural tag than those in paralarval statoliths indicating that paralarvae with the same origin had distinct dispersal pathways. Additionally, stepwise discriminant analysis (SDA) showed there were at least two migration-based groups: 'northern' and 'southern' in the eastern Pacific Ocean. Overall, the derived results can improve our knowledge of the population structure, connectivity and life history of D. gigas. © 2015 John Wiley & Sons Ltd. Source

Feng Y.,Shanghai Ocean University | Feng Y.,Collaborative Innovation Center for Distant Water Fisheries | Chen X.,Shanghai Ocean University | Chen X.,Collaborative Innovation Center for Distant Water Fisheries | Liu Y.,University of Queensland
Fisheries Research

It has been argued that most of the problems concerning fisheries and aquaculture may be rooted in spatial differentiation, and the spatial patterns of fisheries resources have been widely studied. However, there is a general lack of awareness on how changing spatial scales affect the spatial patterns of fisheries resources. This study explores the scaling relations of spatial patterns of the catch-per-unit-effort (CPUE) for Ommastrephes bartramii in the northwest Pacific Ocean. Several spatial indices commonly used to explore the spatial patterns of fisheries were examined, including the count of valid data points (Count index), global Moran's I, Geary's C, General G, the average nearest neighbor (ANN) ratio and Ripley's K function at different spatial scales. The results show that the Count index and the z-scores of three spatial indices (i.e. Moran's I, General G and ANN) exhibit consistent and robust power law relations, while the z-scores of Geary's C and ANN ratio exhibit consistent and robust logarithmic relations. General G exhibits consistent and robust linear functions in September and October and a quadratic polynomial function in August. The spatial patterns observed from Ripley's K-function become less clustered at coarser spatial scales. Based on the peaks of Moran's I and the nadirs of Geary's C, we identified 25' × 25' as the optimum scale for August and October and 20' × 20' for September, and 50' × 50' as the coarsest allowable spatial scale for August and October and 55' × 55' for September, for conducting spatial analysis of O. bartramii in the northwest Pacific Ocean. The methodology presented in this research provides a useful reference to understand the scaling effect and search for the coarsest spatial scale for the survey of fisheries resources. © 2016 Elsevier B.V. Source

Yu W.,Shanghai Ocean University | Yu W.,Collaborative Innovation Center for Distant Water Fisheries | Chen X.J.,Shanghai Ocean University | Chen X.J.,Collaborative Innovation Center for Distant Water Fisheries
Shengtai Xuebao/ Acta Ecologica Sinica

The neon flying squid, Ommastrephes bartramii, is a species of economically important cephalopods distributed in the Northwest Pacific Ocean that has become the fishing target of Chinese squid-jigging fleets. O. bartramii has a short lifespan, which determines vulnerability of the species abundance caused by the changes in environmental conditions at the spawning and feeding grounds. In this study, the fishery data collected by the Chinese squid-jigging fleets and environmental data including sea surface temperature (SST) and chlorophyll a (Chl-a) concentration were used to analyze the seasonal and interannual variability of SST and Chl-a concentration at the spawning and feeding grounds of O. bartramii. The relationship between environmental variability and sea surface temperature anomaly (SSTA) in the Niño 3.4 region and the influences of environmental conditions on the abundance of O. bartramii were also discussed. The results showed that Chl-a concentration was high in the winter and low in the summer, while SST was high in the summer and low in the winter at the spawning ground of the species. At the feeding ground of O. bartramii, the environmental conditions varied seasonally from high SST and Chl-a concentration in the summer to low SST and Chl-a concentration in the winter. Moreover, Chl-a concentration dramatically fluctuated between June and December. The interannual variability of SST and Chl-a concentration at the spawning and feeding grounds were also detected. Furthermore, the mechanism of the SSTA in the Niño 3.4 region that affected the environment at the spawning and fishing grounds of the neon flying squid varied in different abnormal years. The SST at the spawning and fishing grounds increased and variability of Chl-a concentration decreased during the La Niña and normal years, during which period the marine environmental conditions were favorable for the recruitment of O. bartramii and its catch increased. During the El Niño year, the SST and especially Chl-a concentration decreased at the fishing ground, and marine environmental conditions were unfavorable for the recruitment of O. bartramii, resulting in a dramatic decline in the catch of the neon flying squid. Forecasting models of the abundance of neon flying squid based on SSTA and Chl-a concentration anomaly were developed by using the multivariate linear regression. The analyses suggested that the two models could be used to accurately predict the abundance index of O. bartramii; however, the forecasting model based on Chl-a concentration anomaly was better than the SST-based model. © 2015 Ecological Society of China. All rights reserved. Source

Yang M.,Shanghai Ocean University | Yang M.,Collaborative Innovation Center for Distant Water Fisheries | Lin J.,Shanghai Ocean University | Lin J.,Collaborative Innovation Center for Distant Water Fisheries | And 3 more authors.
Ecological Engineering

Zirconium-modified zeolite (ZrMZ) may be a lake remediation tool designed to control the internal phosphorus (P) loading from sediments. Batch experiments were conducted to investigate the effect of adsorbent dosage on the adsorption of phosphate on ZrMZ, as well as the adsorption characteristics of phosphate on the raw and ZrMZ-amended sediments. The sequential extraction methods were used to investigate the forms of P in the phosphate-adsorbed ZrMZ. The ZrMZ was effective for the removal of phosphate from water. The sequential extraction of P from the phosphate-adsorbed ZrMZ under laboratory conditions suggested that about 6% of P bound by ZrMZ was release-sensitive, while about 94% of bound P was unlikely to be released under reducing and common pH (5-9) conditions. The equilibrium adsorption data of phosphate on the raw and ZrMZ-amended sediments at initial P concentrations of 1-12mg/L could be described by the Langmuir and Freundlich isotherm models. The adsorption kinetics of phosphate on the raw and ZrMZ-amended sediments followed a pseudo-second-order model, and the adsorption process was spontaneous and endothermic in nature. The presence of Cl- or SO4 2- showed no competing effect on the adsorption of phosphate on the raw and ZrMZ-amended sediments, while the presence of HCO3 - or SiO3 2- inhibited the adsorption of phosphate. The zero-equilibrium P concentration (EPC0) for the ZrMZ-amended sediment was much lower than that for the raw sediment. The phosphate adsorption capacity for the ZrMZ-amended sediment was much higher than that for the raw sediment. Results of this work indicate that the addition of ZrMZ into the lake sediment can reduce the potential of phosphate-P release from the sediment as well as can increase the phosphate-P adsorption capacity of the sediment. © 2014 Elsevier B.V. Source

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