scholarly journals Autumn ichthyoplankton assemblage in the Yangtze Estuary shaped by environmental factors

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1922 ◽  
Author(s):  
Hui Zhang ◽  
Weiwei Xian ◽  
Shude Liu
Keyword(s):  
Environmental Factors ◽  
Correspondence Analysis ◽  
Canonical Correspondence Analysis ◽  
Environmental Changes ◽  
Yangtze Estuary ◽  
Environmental Data ◽  
The Yangtze Estuary ◽  
Annual Variations ◽  
Trichiurus Lepturus ◽  
Seawater Salinity

This study investigated the response of the ichthyoplankton community to environmental changes in the Yangtze Estuary using canonical correspondence analysis. Ichthyoplankton community and environmental data were recorded during the autumns of 1998, 2000, 2002, 2003, 2004, 2007 and 2009. Among the ichthyoplankton, the dominant larval and juvenile families were the Engraulidae, Gobiidae and Salangidae, and the most common eggs were fromTrichiurus lepturus. The ichthyoplankton was identified via canonical correspondence analysis to three assemblages: an estuary assemblage dominated byChaeturichthys stigmatias, a coastal assemblage dominated byEngraulis japonicusandStolephorus commersonii, and an offshore assemblage dominated byTrichiurus lepturus. Regarding environmental factors in the Yangtze Estuary, suspended matter and surface seawater salinity were the main factors influencing the distributions of the different assemblages, while sediment from the Yangtze River during the rainy season and chlorophyllawere the principle drivers of the annual variances in the distribution of ichthyoplankton assemblages. Our aims in this study were to provide detailed characterizations of the ichthyoplankton assemblage in the autumns of seven years, examine the long-term dynamics of autumn ichthyoplankton assemblages, and evaluate the influence of environmental factors on the spatial distribution and inter-annual variations of ichthyoplankton assemblages associated with the Yangtze Estuary.

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.

scholarly journals Influence of Hydrological Variables on Macrophytes in a Black Water River Ecosystem

2021 ◽  
Vol 25 (2) ◽  
pp. 151-158
Author(s):  
E.D. Anwana ◽  
F.O. Ogbemudia ◽  
R.E. Ita ◽  
P.E. Sunday
Keyword(s):  
Correspondence Analysis ◽  
Canonical Correspondence Analysis ◽  
Environmental Changes ◽  
Great Influence ◽  
Oxygen Demand ◽  
Ceratophyllum Demersum ◽  
River Ecosystem ◽  
Black Water ◽  
Black Water River ◽  
Hydrological Variables

This study assessed the influence of hydrological variables on macrophytes in a Black Water River ecosystem of Enyong River in Itu and Ibiono Local Government Areas of Akwa Ibom and Cross Rivers States, Nigeria. Four vegetation plots were chosen and in each of the plots, four belt transect were laid. In each transect, macrophyte were systematically sampled in four 10 m × 10 m quadrat at regular intervals. Macrophytes were identified to species level and their frequency and density determined. Water samples were obtained in each quadrat where the macrophytes were sampled and analyzed for their physicochemical properties using standardized methods. Altogether, 10 macrophyte species were encountered. Vossia cuspidata had the highest density (100.00±8.00 st/ha) and frequency values (100 %). Sacciolepis africana had the least density of 7.10±0.45 st/ha while Ludwigia octovalvis, Persicaria senegalensis, andSacciolepis africana had the least frequency of 25 %, respectively. The pH of the water was strongly acidic (5.54±0.03), electrical conductivity was low (20.00±5.77 µs/cm), temperature (29.00±1.10 ºC), Dissolved Oxygen (DO) (9.20±0.12 mg/l) and turbidity (7.10±0.06 NTU) values were high while Biological Oxygen Demand (BOD) (2.00±0.29 mg/l) Total Dissolved Solids (TDS) (10.00±0.29 mg/l) and Total Suspended Solids (TSS) were low (5.00±1.15 mg/l). Water Nutrients followed this decreasing order; chloride (3.55±0.02 mg/l) > nitrate (2.45±0.03 mg/l) > sulphate (2.02±0.06 mg/l) > phosphate (0.08±0.01 mg/l) and sulphide (0.03±0.02 mg/l). Heavy metals also followed this descending order; Pb (0.50±0.03 mg/l) > Zn (0.07±0.02 mg/l) > Cu (0.03±0.02 mg/l). Canonical Correspondence Analysis delineated 11 hydrological variables (temperature, pH, sulphate, turbidity, phosphate, BOD, nitrate, DO, TDS, sulphide and TSS) which exerted great influence on macrophyte distribution. V. cuspidata had affinity to pH and temperature, Sacciolepis africana had affinity to turbidity and BOD, Ludwigia octovalvis and Nymphaea lotus had affinity to sulphate and chloride, respectively, while Ipomoea aquatica and Alternanthera sessils had affinity to phosphate. On the other hand, Persicaria senegalensis, Salvinia molesta, Azolla pinnata and Ceratophyllum demersum had affinities to sulphide, DO, TSS and TDS, respectively. Since hydrological variables regulate macrophyte diversity and distribution, this study calls for consistent, monitoring and management of this ecosystem against future environmental changes. Keywords: Aquatic plants, Black water, Canonical Correspondence Analysis, Ordination

scholarly journals Oligochaete (Annelida, Clitellata) сommunities in lakes of the Ural Mountains (Russia)

Zoosymposia ◽  
2014 ◽  
Vol 9 (1) ◽  
pp. 77-94 ◽  
Author(s):  
MARIA BATURINA ◽  
TARMO TIMM ◽  
OLGA LOSKUTOVA
Keyword(s):  
Environmental Factors ◽  
Correspondence Analysis ◽  
Canonical Correspondence Analysis ◽  
Species Abundance ◽  
Species Level ◽  
The Other ◽  
Ural Mountains ◽  
Factors Influencing ◽  
The Relationship

The oligochaete fauna of 25 lakes located in the Polar and Subpolar regions of the Ural Mountains in Russia was studied. In total, 46 oligochaete taxa were collected, 32 of them identified to species level. Naididae had the highest number of taxa (19); the other taxa belonged to Pristinidae (2), Enchytraeidae (6), Tubificidae (10), Lumbriculidae (8) and Lumbricidae (1). Canonical correspondence analysis (CCA) was used to characterize the relationship between abundance of oligochaete species, abundance and biomass of all oligochaetes, abundance of separate families and environmental factors. Latitude, elevation, silt, detritus, moss and algal periphyton and depth were found to be factors influencing the distribution of oligochaetes.

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