scholarly journals Elevated precipitation alters the community structure of spring ephemerals by changing dominant species density in Central Asia

2020 ◽  
Vol 10 (4) ◽  
pp. 2196-2212
Author(s):  
Yangyang Jia ◽  
Yu Sun ◽  
Tao Zhang ◽  
Zhaoyong Shi ◽  
Baidengsha Maimaitiaili ◽  
...  
Keyword(s):  
Community Structure ◽  
Central Asia ◽  
Dominant Species ◽  
Species Density ◽  
Spring Ephemerals

scholarly journals The use of diversity indices for local assessment of marine sediment quality

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shinya Hosokawa ◽  
Kyosuke Momota ◽  
Anthony A. Chariton ◽  
Ryoji Naito ◽  
Yoshiyuki Nakamura
Keyword(s):  
Community Structure ◽  
Sample Size ◽  
Small Sample Size ◽  
Benthic Communities ◽  
Sediment Quality ◽  
Diversity Indices ◽  
Small Sample ◽  
Species Density ◽  
Local Case ◽  
Two Indices

AbstractDiversity indices are commonly used to measure changes in marine benthic communities. However, the reliability (and therefore suitability) of these indices for detecting environmental change is often unclear because of small sample size and the inappropriate choice of communities for analysis. This study explored uncertainties in taxonomic density and two indices of community structure in our target region, Japan, and in two local areas within this region, and explored potential solutions. Our analysis of the Japanese regional dataset showed a decrease in family density and a dominance of a few species as sediment conditions become degraded. Local case studies showed that species density is affected by sediment degradation at sites where multiple communities coexist. However, two indices of community structure could become insensitive because of masking by community variability, and small sample size sometimes caused misleading or inaccurate estimates of these indices. We conclude that species density is a sensitive indicator of change in marine benthic communities, and emphasise that indices of community structure should only be used when the community structure of the target community is distinguishable from other coexisting communities and there is sufficient sample size.

Diversity and community structure of Ephemeroptera in freshwater stream of Megamalai hills, Tamil Nadu, India

ENTOMON ◽  
2021 ◽  
Vol 46 (4) ◽  
pp. 279-284
Author(s):  
S. Barathy ◽  
T. Sivaruban ◽  
Srinivasan Pandiarajan ◽  
Isack Rajasekaran ◽  
M. Bernath Rosi
Keyword(s):  
Community Structure ◽  
Species Diversity ◽  
Air Temperature ◽  
Tamil Nadu ◽  
Dominant Species ◽  
Diversity Indices ◽  
Low Diversity ◽  
Freshwater Stream ◽  
Species Diversity Indices ◽  
High Diversity

In the study on the diversity and community structure of Ephemeroptera in the freshwater stream of Chinnasuruli falls on Megamalai hills, a total of 523 specimens belonging to thirteen genera and five families were collected in six month periods. Of the five families, Teloganodidae and Leptophlebiidae exhibited high diversity and Caenidae showed low diversity. Choroterpes alagarensis (Leptophlebiidae) is the most dominant species. Diversity indices such as Shannon and Simpson indices showed that diversity was maximum in November and December and it was minimum in August and January. Canonical Correspondence Analysis revealed that rainfall, water flow, turbidity, and air temperature were the major stressors in affecting the Ephemeropteran community structure.

scholarly journals Characteristics of Benthos communities in Laoting area of Hebei Province

2020 ◽  
Vol 206 ◽  
pp. 02024
Author(s):  
Li Guanglou ◽  
Cao Hongmei ◽  
Ye wei
Keyword(s):  
Community Structure ◽  
Benthic Community ◽  
Dominant Species ◽  
Diversity Index ◽  
Hebei Province ◽  
Benthic Community Structure ◽  
Number Of Species ◽  
Evenness Index ◽  
Sea Area ◽  
Richness Index

According to a survey of benthos in the Laoting sea area of Hebei Province on May 24th 2019, a total of 40 benthos species were obtained, of which mollusks have the largest number, followed by annelids and arthropods. The dominant species are Sternaspis sculata and Ringicula doliaris. The number of species obtained in this survey is much lower than the historical average. The diversity index is significantly lower than that in the April 2008 survey, and the evenness index and richness index have declined slightly, indicating that the benthic community structure in this sea area tends to be simplistic, stability tends to deteriorate.

Epiphyton of oligotrophic lakes of Leningrad region

2021 ◽  
pp. 71-79
Author(s):  
Elena V. Stanislavskaya
Keyword(s):  
Community Structure ◽  
Dominant Species ◽  
Taxonomic Composition ◽  
Species Level ◽  
Taxonomic Structure ◽  
Leningrad Region ◽  
Oligotrophic Lakes ◽  
Epiphytic Algae ◽  
Lake Ecosystems ◽  
Epiphytic Communities

Here are results of investigation of taxonomic composition, community structure and dominant species of epiphytic algae in 12 oligotrophic lakes located in different geomorphic regions of Leningrad region. In summer epiphytic communities there were 385 algal taxa, they belonged to 6 taxonomic divisions: Cyanophyta (Cyanoprokaryota) – 50 (13%), Bacillaryophyta – 175 (45%), Chlorophyta – 37 (10%), Charophyta – 118 (30%), Xanthophyta – 4 (1,55%), Rhodophyta – 1 (0,45%). The taxonomic structure of each lake was predominant diatoms and desmids, but the biomass was dominated by zygnems and green algae. In total, the taxonomic composition of the epiphyton in the studied lakes is similar, the differences are revealed at the species level. The structure of dominanting epiphyton complex was rather constant and composed by a small number of species. The greatest contribution to the epiphyton was made by Tabellaria flocculosa and species of the genus Bulbochaete. The structure of the epiphyton reflects the undisturbed nature of lake ecosystems, as well as their northern location.

scholarly journals Fish assemblages in a tidal flat

2003 ◽  
Vol 46 (2) ◽  
pp. 233-242 ◽  
Author(s):  
Ana Lúcia Vendel ◽  
Sabine Granado Lopes ◽  
César Santos ◽  
Henry Louis Spach
Keyword(s):  
Cluster Analysis ◽  
Community Structure ◽  
Tidal Flat ◽  
Seasonal Changes ◽  
Dominant Species ◽  
Fish Assemblages ◽  
Seasonal Pattern ◽  
Abundant Species ◽  
Structure Index ◽  
Total Capture

Studies were carried out on fish assemblages in a tidal flat. Samples were obtained monthly at low tide of the half moon in the tidal flat of Paranaguá Bay, Brazil, with two seine nets, one with a 1 mm mesh, 30 m in length and 3 m in height and another with a 10 mm mesh, 65 m in length and 2 m in height. A total of 8,890 fish were captured, comprising 24 families and 53 species. The most abundant species were Harengula clupeola and Atherinella brasiliensis, which represented 63.4% of the total, capture. A seasonal tendency was observed in the abundance of fishes, with less fishes being captured during winter and part of spring. The number of species showed a seasonal pattern, with the gradual decrease through winter and a marked increase in summer. The community structure index indicated seasonal changes in the assemblage. The faunistic similarities between months separated the 12 months into four major groups. The seasonal pattern was apparent in the numerically dominant species and the Cluster Analysis revealed five main groups.

Species diversity, community structure and distribution of phytoplankton in the Changjiang estuary during dry and flood periods

2013 ◽  
Vol 94 (3) ◽  
pp. 459-472 ◽  
Author(s):  
P.Y. Guo ◽  
H.T. Shen ◽  
J.H. Wang
Keyword(s):  
Surface Layer ◽  
Community Structure ◽  
Species Diversity ◽  
Species Distribution ◽  
Dominant Species ◽  
Changjiang Estuary ◽  
Freshwater Species ◽  
Phytoplankton Species ◽  
Dry Period ◽  
Flood Period

This paper reports on the phytoplankton community, its composition, structure and distribution in Changjiang estuary from February 1999 to March 2000. Two hundred and eight species were identified in the dry and flood periods. Diatoms, with 143 species observed, was the most abundant phytoplankton group, accounting for 68.75% of the total phytoplankton species number. Skeletonema costatum was dominant among all the species. The phytoplankton of Changjiang estuary in China was divided into five ecological categories: freshwater species, estuary brackish water species, inshore low salinity species, inshore widespread species and off-sea high salinity species. During the dry period, the major phytoplankton populations in the surface layer were estuary inshore and offshore populations, distinguished from the composition of the bottom layer. The community structure was similar in the two layers during the flood period. The phytoplankton species diversity was calculated for Simpson, Shannon–Weaver diversity and evenness indices, and found to be higher in the dry period, due to the simple dominant species and low spatial heterogeneity in the flood period. Higher phytoplankton abundance was observed in the surface layer during the flood period. The phytoplankton species distribution, coinciding with the dominant species distribution, varied with salinity, and their abundance correlated significantly with nutrients and light.

Seasonal variation in population and community structure of shrews in a tropical forest of Gabon

2005 ◽  
Vol 21 (2) ◽  
pp. 161-169 ◽  
Author(s):  
Violaine Nicolas ◽  
Patrick Barrière ◽  
Marc Colyn
Keyword(s):  
Community Structure ◽  
Seasonal Variation ◽  
Dominant Species ◽  
Abundant Species ◽  
Dry Season ◽  
Reproductive Phenology ◽  
Ecological Constraints ◽  
Species Dominance ◽  
Composition Structure ◽  
Over Time

The composition, structure and reproductive phenology of a shrew community were investigated for 1 y at two neighbouring sites in an undisturbed African forest of south-western Gabon. We captured 717 shrews, belonging to four genera and 10 species. The data were analysed to answer three main questions: (1) to what extent does the shrew abundance vary seasonally? (2) is there a shift in species dominance over time? and (3) does the intensity of breeding activity vary seasonally? The number of species captured varied seasonally and tended to be least during the period of minimal trap success. Trap success for the four most abundant species (Sylvisorex johnstoni, Crocidura batesi, Paracrocidura schoutedeni and Sylvisorex ollula) varied seasonally with a minimum around the long dry season. Sylvisorex johnstoni remained the dominant species throughout the year. Seasonal variation in trap success of shrews might be related, at least partly, to their reproductive characteristics. Litter size, based on embryo counts, ranged from 1–4 among the species. Breeding occurred throughout the year, but its intensity was lower during the long dry season corresponding with the period of higher ecological constraints for shrews.

Studies on the Community Structure of Phytoplankton in the Sea near Sanmen Bay

2012 ◽  
Vol 518-523 ◽  
pp. 502-508 ◽  
Author(s):  
Gen Hai Zhu ◽  
Jian Qian ◽  
Li Hong Chen
Keyword(s):  
Community Structure ◽  
Dominant Species ◽  
Red Tide ◽  
Skeletonema Costatum ◽  
Continuous Observation ◽  
Dominant Group ◽  
Average Cell ◽  
Cell Abundance ◽  
Sanmen Bay ◽  
Sea Area

This paper reports the phytoplankton investigation results which were collected in 15 observation stations and a day-night continuous observation station in the sea area near Sanmen Bay (29° 00'00 "~ 29° 10'26 "N, 121° 34'43" ~ 121° 47'06 "E) in spring(April), summer (July), autumn (October) of 2007 and winter (January) of 2008. After microscopic observation and identification, a total of 6 phyla, 56 genera, 146 species were identified in the sea near Sanmen Bay. The seasonal species change was spring (101)> autumn (96)> summer (96)> winter (85). The cell abundance of phytoplankton in the sea near Sanmen Bay was 0.72103～1.3106 cells /dm3, and the average cell abundance was 5.13104 cells /dm3. The mean cell abundance in winter was 1.27105cells/dm3 >4.72104cells/dm3 in autumn > 1.63104 cells/dm3 in spring > 2.51103cells/dm3 in summer. During the 24-hour continuous observation, in the day time, particularly in the afternoon, the photosynthesis was strong, and the cell abundance of phytoplankton was high; at night, especially in the latter half of the night or wee hours, the photosynthesis was weak, and the cell abundance of phytoplankton was low. The dominant species of phytoplankton in the Sanmen Bay was Skeletonema costatum. Ecological types of phytoplankton can be divided into three groups: (1) inner bay and coastal temperate group; (2) eurythermal and euryhaline group; (3) warm water off-shore group. Inner bay and coastal eurythermal and euryhaline group was the dominant group. The amounts of other groups were less. Totally 64 red-tide species were observed in the sea area near Sanmen Bay, of which, diatoms was predominant, 40 species; dinoflagellates was 19 species; Cyanophyta was 2 species; Euglena、Chrysophyceae and Protozoa was 1 specie respectively. The average cell abundance of the main red-tide organisms in the sea area near Sanmen Bay was 5.6102 cells/dm3～1.2105 cells/dm3. The dominant species composition and community structure of phytoplankton were mainly composed of diatoms, such as Skeletonema costatum, Ditylum brightwelli, Coscinodiscus jonesianus, Thalassiosira eccentrica, Leptocylindrus danicus, Chaetoceros lorenzianus; pyrrophyta, such as Ceratium fusus, Ceratium tripos, Ceratium furca etc.

scholarly journals The use of diversity indices for local assessment of marine sediment quality

2021 ◽  
Author(s):  
Shinya Hosokawa ◽  
Kyosuke Momota ◽  
Anthony Chariton ◽  
Ryoji Naito ◽  
Yoshiyuki Nakamura
Keyword(s):  
Community Structure ◽  
Benthic Communities ◽  
Sediment Quality ◽  
Diversity Indices ◽  
Small Sample ◽  
Species Density ◽  
Sample Sizes ◽  
Local Case ◽  
Marine Sediment Quality ◽  
Small Sample Sizes

Abstract Diversity indices are commonly used to measure changes in marine benthic communities. Although diversity indices give a good understanding of how biological communities respond to changes in sediment, responses of these indices can vary because of small sample sizes, and insensitive responses can result from an inappropriate choice of test community. This study focused on species density and two indices of community structure and explored how they respond to variations in sediment characteristics in our target region, Japan, and in two local areas within this region. Our analysis of the Japanese regional dataset showed a decrease in species density and the dominance of a few species as sediment conditions degraded. Local case studies showed that species density responded to sediment degradation at sites where the community was variable. However, the indices for community structure sometimes became misleading because of inaccurate estimates with small sample sizes, and could become insensitive because of masking by community variability. We conclude that species density is a sensitive indicator of change for marine benthic communities, but that indices of community structure should only be used when there is a sufficient sample size and a test community is distinguishable from other coexisting communities.

scholarly journals Struktur Komunitas Alga Perifiton Sungai dalam Gua Batu Asahan di Sumpur Kudus Kabupaten Sijunjung Sumatera Barat

2019 ◽  
Vol 7 (1) ◽  
pp. 27
Author(s):  
Izmiarti Izmiarti
Keyword(s):  
Community Structure ◽  
Dominant Species ◽  
Diversity Index ◽  
Similarity Index ◽  
Survey Method ◽  
Clean Water ◽  
Periphyton Community ◽  
West Sumatra ◽  
Number Of Individuals

The cave ecosystem has a unique environment because it receives minimal sunlight and does not even get sunlight at all. Dark conditions in the cave will affect producers such as periphyton algae that live in rivers in caves that need sunlight for photosynthesis. This study aims to determine the periphyton community structure in the river in the Batu Asahan Cave in Sumpur Kudus, Sijunjung District, West Sumatra. This research held in August 2016. The research was carried out by survey method at 3 stations: bright, dim and dark zones. The results showed that periphyton were found as many as 22 species classified as Bacillariophycea 13 species, Cyanophyceae 5 species, Chlorophyceae and Euglenophyceae each of 2 species. Based on the number of individuals Bascillariophyceae 67.0%, Cyanophyceae 24.49%, Chlorophyceae 4.79% and Euglenophyceae 3.72%. Population density in each zone was low, ranges from 1.26 - 2.82 ind / cm2. The dominant species vary in each zone which is the highest shown by Synedra ulna (Bacillariophyceae) and Oscillatoria tenuis (Cyanophyceae). Diversity index ranging from 2.11-2.47 is not significantly different between zones, indicating the quality of clean water. The equitability index was high (E = 0.88-0.96) show the populations in the community evenly. Similarity index between zones was low (C = 25 - 56%). Fisicochemical factors of water indicate the quality of clean water supports the life of periphyton algae in the river.

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