scholarly journals Spring Ichthyoplankton Assemblage Structure in the Yangtze Estuary Under Environmental Factors

2021 ◽  
Vol 8 ◽  
Author(s):  
Yibang Wang ◽  
Cui Liang ◽  
Zhaomin Chen ◽  
Shude Liu ◽  
Hui Zhang ◽  
...  
Keyword(s):  
Dominant Species ◽  
Large Scale ◽  
Yangtze Estuary ◽  
Assemblage Structure ◽  
The Yangtze Estuary ◽  
Larimichthys Polyactis ◽  
Factors Affecting ◽  
Coilia Mystus ◽  
Trachidermus Fasciatus ◽  
Fish Spawning

Estuaries, where fresh and salty water converge, provide abundant nutrients for ichthyoplankton. Ichthyoplankton, including fish eggs, larvae, and juveniles, are important fishery recruitment resources. The Yangtze Estuary and its adjacent waters comprise a typical large-scale estuary and supply many important fish spawning, feeding, and breeding areas. In this study, 1,291 ichthyoplankton individuals were collected in the Yangtze Estuary in spring, from 2013 to 2020. The aims of the study were to provide detailed information on characteristics of the ichthyoplankton assemblage, explore interannual variation, and evaluate the effects of environmental variables on the temporal variation in assemblage structure. Twenty-six species in seventeen families were identified. The dominant species were Coilia mystus, Chelidonichthys spinosus, Engraulis japonicus, Hypoatherina valenciennei, Larimichthys polyactis, Salanx ariakensis, Stolephorus commersonnii, and Trachidermus fasciatus. The ichthyoplankton assemblage changed significantly over time, and Chelidonichthys spinosus became one of the dominant species. Canonical correspondence analysis showed that temperature and chlorophyll a were the key factors affecting the assemblage structure in the Yangtze Estuary in spring.

scholarly journals Seasonal variations of the ichthyoplankton assemblage in the Yangtze Estuary and its relationship with environmental factors

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6482 ◽  
Author(s):  
Hui Zhang ◽  
Weiwei Xian ◽  
Shude Liu
Keyword(s):  
Seasonal Variations ◽  
Historical Data ◽  
Wiener Index ◽  
Abundant Species ◽  
Diversity Indices ◽  
Yangtze Estuary ◽  
The Yangtze Estuary ◽  
Factors Affecting ◽  
Annual Variations ◽  
Major Factors

Seasonal variations of the ichthyoplankton assemblage and its relationship with the environment were analyzed based on four seasonal surveys during 2012. Historical data was collected to be compared with results from previous years in order to indicate the seasonal and inter-annual variation of the ichthyoplankton assemblage in the Yangtze Estuary and the adjacent waters. A total of 3,688 individuals belonging to 5 orders, 9 families, and 15 species were collected. No samples were collected in the winter cruise. In 2012, all samples were separated into four ecotypes, which is comparable with the historical data from previous years. The Engraulis japonicus was the most abundant species of all teleost fishes. The E. japonicus was captured in every season and contributed the most to the abundance of ichthyoplankton, which was greater than that of previous years. This result may be due to the periodic fluctuations of E. japonicus or from the displacement of spawning grounds offshore for environmental reasons. The diversity indices of the assemblage were significantly different among seasons, with the number and abundance of the species peaking in the spring, while richness, evenness and diversity indices peaked in the autumn. The species richness of the ichthyoplankton varied from 0.74 to 1.62, the Pielou evenness index varied from 0.10 to 0.49 and the Shannon–Wiener index varied from 0.19 to 1.04. The results of CCA analysis showed that the major factors affecting the ichthyoplankton assemblage differed throughout the seasons. Chla was the key factor affecting the ichthyoplankton in 2012. These seasonal and inter-annual variations likely resulted from migrations associated with fish spawning as well as the environment. Compared with data from previous studies, the relationship between the assemblage structure of ichthyoplankton and corresponding environmental variables have undergone a decline.

Reproductive biology of Coilia mystus (Linnaeus) from the Yangtze Estuary, China: responses to overexploitation

2011 ◽  
Vol 27 (5) ◽  
pp. 1197-1202 ◽  
Author(s):  
W.-P. He ◽  
Y.-X. Li ◽  
M. Liu ◽  
K. V. Radhakrishnan ◽  
Z.-J. Li ◽  
...  
Keyword(s):  
Reproductive Biology ◽  
Yangtze Estuary ◽  
The Yangtze Estuary ◽  
Coilia Mystus

scholarly journals Validation of a method of estimating age, modelling growth, and describing the age composition of Coilia mystus from the Yangtze Estuary, China

2008 ◽  
Vol 65 (9) ◽  
pp. 1655-1661 ◽  
Author(s):  
Wenping He ◽  
Zhongjie Li ◽  
Jiashou Liu ◽  
Yuxuan Li ◽  
Brian R. Murphy ◽  
...  
Keyword(s):  
Age Structure ◽  
Growth Function ◽  
Yangtze Estuary ◽  
Growth Patterns ◽  
Age Classes ◽  
The Yangtze Estuary ◽  
Age Composition ◽  
Coilia Mystus ◽  
Von Bertalanffy Growth Function ◽  
Annual Periodicity

Abstract He, W., Li, Z., Liu, J., Li, Y., Murphy, B. R., and Xie, S. 2008. Validation of a method of estimating age, modelling growth, and describing the age composition of Coilia mystus from the Yangtze Estuary, China. – ICES Journal of Marine Science, 65: 1655–1661. A collection of 577 Coilia mystus was made during April 2006 and 2007 from China’s Yangtze Estuary to estimate the age structure and growth patterns of the population. Examination of sectioned sagittal otoliths revealed a periodic straight/curved growth pattern. The straight zone was from April to November, and the curved zone from October to May, indicating annual periodicity. Annual periodicity was also verified by margin zone analysis. The shift from a curved-zone to the next straight-zone stanza was defined as an annulus. The fish from which the otoliths were taken were 0–5 years old. The von Bertalanffy growth function was fitted to standard length (LS)-at-age data as LS = 215.16 (1 – e−0.53 (t+ 0.30)) (n = 577, r2 = 0.81, p < 0.05). The mature females included five age classes, ages 1 and 2 accounting for 74.3% of the population. The mature males included fish aged 1 and 2, those at age 1 accounting for 86.4% of the population. Mean length was smaller, and annual growth less, for mature males than for females of comparable age. The study demonstrated that the Yangtze population of C. mystus consists of more age classes than previously thought and that the age structure of the population needs to be considered in management decisions.

scholarly journals Sampling Designs for Monitoring Ichthyoplankton in the Estuary Area: A Case Study on Coilia mystus in the Yangtze Estuary

2022 ◽  
Vol 8 ◽  
Author(s):  
Xiangyu Long ◽  
Rong Wan ◽  
Zengguang Li ◽  
Dong Wang ◽  
Pengbo Song ◽  
...  
Keyword(s):  
Estimation Error ◽  
Additive Model ◽  
Yangtze Estuary ◽  
Sample Sizes ◽  
The Yangtze Estuary ◽  
The North ◽  
Coilia Mystus ◽  
Tweedie Distribution ◽  
Optimization Methodology ◽  
Cost Efficient

A fishery-independent survey can provide detailed information for fishery assessment and management. However, the sampling design for the survey on ichthyoplankton in the estuary area is still poorly understood. In this study, we developed six stratified schemes with various sample sizes, attempting to find cost-efficient sampling designs for monitoring Coilia mystus ichthyoplankton in the Yangtze Estuary. The generalized additive model (GAM) with the Tweedie distribution was used to quantify the “true” distribution of C. mystus eggs and larvae, based on the data from the fishery-independent survey in 2019–2020. The performances of different sampling designs were evaluated by relative estimation error (REE), relative bias (RB), and coefficient of variation (CV). The results indicated that appropriate stratifications with intra-stratum homogeneity and inter-stratum heterogeneity could improve precision. The stratified schemes should be divided not only between the North Branch and South Branch but between river and sea. No less than two stratifications in the South Branch could also get better performance. The sample sizes of 45–55 were considered as the cost-efficient range. Compared to other monitoring programs, monitoring ichthyoplankton in the estuary area required a more complex stratification and a higher resolution sampling. The design ideology and optimization methodology in our study would provide references to sampling designs for ichthyoplankton in the estuary area.

scholarly journals The Non-stationary Environmental Effects on Spawning Habitat of Fish in Estuaries: A Case Study of Coilia mystus in the Yangtze Estuary

2021 ◽  
Vol 8 ◽  
Author(s):  
Dong Wang ◽  
Rong Wan ◽  
Zengguang Li ◽  
Junbo Zhang ◽  
Xiangyu Long ◽  
...  
Keyword(s):  
Habitat Selection ◽  
Saltwater Intrusion ◽  
Yangtze Estuary ◽  
Sea Surface ◽  
Spawning Habitat ◽  
The South ◽  
The Yangtze Estuary ◽  
Commercial Fish ◽  
Coilia Mystus ◽  
Gwr Model

The estuarine areas provide necessary spawning habitat, nursing habitat, and migratory for a variety of fishes and the environmental conditions are of significant heterogeneity. Coilia mystus is the key commercial fish that spawns in the Yangtze Estuary and the yield has declined sharply in the past 30 years. In order to understand the spawning habitat selection mechanism of C. mystus, the geographically weighted regression (GWR) model was applied to explore the non-stationary effect of environmental variables [e.g., the sea surface temperature (SST) and the sea surface salinity (SSS)] and geographical variables [e.g., the distance to the coast (DTC) and the depth (DEP) of water] on the egg density distribution of C. mystus. The data were derived from the spring and summer ichthyoplankton surveys carried out from 2019 to 2020 in the Yangtze Estuary, China. The GWR model results showed that the key variables in different seasons had spatial non-stationary effects on the distribution of spawning habitat of C. mystus, which were mainly caused by regional rise in temperature and saltwater intrusion of the South Branch. In the spring, the SSS, the DTC, and the DEP were the main impact factors and saltwater intrusion in the South Branch might lead to the trend that the spawning habitat moved further upstream to the Changxing Island. The SST was most important in the summer and the relatively lower SST was more crucial in the spawning habitat selection than the DTC and the DEP. The GWR model performed well in the study of C. mystus potential spawning habitat in the Yangtze Estuary. We recommend that more attention should be paid in regional variation of environmental factors to explore fish potential spawning habitat in the estuarine areas.

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