scholarly journals Spatial and temporal organization of aquatic insects assemblages in the longitudinal gradient of a tropical river

2001 ◽  
Vol 61 (2) ◽  
pp. 295-304 ◽  
Author(s):  
D. F. BAPTISTA ◽  
L. F. M. DORVILLÉ ◽  
D. F. BUSS ◽  
J. L. NESSIAMIAN
Keyword(s):  
Correspondence Analysis ◽  
Aquatic Insects ◽  
Rainy Season ◽  
Similarity Index ◽  
Mantel Test ◽  
Temporal Organization ◽  
Longitudinal Gradient ◽  
Physical And Chemical Variables ◽  
And Cluster Analysis ◽  
Physical And Chemical

The distribution and abundance of aquatic insects were studied in the longitudinal gradient of the watershed of Macaé River, a coastal Atlantic Forest river in South-eastern Brazil. Sampling stations were selected in the first, second, fourth, fifth, and sixth orders and sampled in April, July, and October 1995. This represented the end of the rainy season, the dry season, and the beginning of another rainy season, respectively. In each month four samples were collected using a Surber sampler from each of the following substrates: sand, litter deposited in pool areas, litter in riffle areas, and stones. A total of 46,431 specimens of aquatic insects belonging to ten orders were obtained. The data were analyzed by the multivariate methodologies of Correspondence Analysis (CA) and Cluster Analysis (UPGMA) using the similarity index of Morisita, for all three months. Both showed a significant faunal disrupture in the river, which can be divided in two sections: the upper one, from first to fourth orders, and the lower section, including fifth and sixth orders. The same results were obtained with presence-absence matrices, using Jaccard similarity index, showing that the changes are not only due to quantitative differences. A Mantel test was used to compare the assemblage composition temporally and no difference was detected between the three months. Moreover, a Canonical Correspondence Analysis (CCA) was applied to the data to check which of the 14 physical and chemical variables significantly explained macroinvertebrate community variation. The most significant variables were conductivity, CPOM, and pH for the upper stations (1st, 2nd and 4th orders), and alkalinity, FPOM, and HCO3 for the lower stations (5th and 6th orders).

scholarly journals Phytoplankton abundance, dominance and coexistence in an eutrophic reservoir in the state of Pernambuco, Northeast Brazil

2011 ◽  
Vol 83 (4) ◽  
pp. 1313-1326 ◽  
Author(s):  
Giulliari A. S. T. Lira ◽  
Elcida L. Araújo ◽  
Maria Do Carmo Bittencourt-Oliveira ◽  
Ariadne N. Moura
Keyword(s):  
Rainy Season ◽  
Phytoplankton Community ◽  
Dry Season ◽  
Cylindrospermopsis Raciborskii ◽  
Phytoplankton Abundance ◽  
Vertical Variation ◽  
Total Phytoplankton ◽  
Physical And Chemical Variables ◽  
Different Depths ◽  
Physical And Chemical

The present study reports the phytoplankton abundance, dominance and co-existence relationships in the eutrophic Carpina reservoir, Pernambuco, Brazil. Sampling was carried out at six different depths bimonthly at a single reservoir spanning two climatic periods: dry season (January, September, and November 2006) and rainy season (March, May, and July 2006). Density, abundance, dominance, specific diversity and equitability of the community were determined, along with chlorophyll a, and physical and chemical variables of the environment. Eight species were considered abundant, and their densities corresponded to more than 90% of the total phytoplankton community quantified. Cyanobacteria represented more than 80% of this density. Cylindrospermopsis raciborskii was the only dominant taxon in the dry season, and was co-dominant in the rainy season. C. raciborskii, Planktothrix agardhii and Geitlerinema amphibium had the greatest densities and lowest vertical variation coefficients. The statistical analysis indicated relationships with vertical and seasonal variations in the phytoplankton community and the following variables: total dissolved solids, water temperature, electrical conductivity and pH. The changes in the environmental variables were discrete and regulated by the establishment of precipitation however, they were able to promote vertical and seasonal instability in the structure of the phytoplankton community.

scholarly journals Diversity and habitat preference of aquatic insects along the longitudinal gradient of the Macaé River basin, Rio de Janeiro, Brazil

2001 ◽  
Vol 61 (2) ◽  
pp. 249-258 ◽  
Author(s):  
D. F. BAPTISTA ◽  
D. F. BUSS ◽  
L. F. M. DORVILLÉ ◽  
J. L. NESSIMIAN
Keyword(s):  
River Basin ◽  
Aquatic Insects ◽  
Habitat Preference ◽  
Rainy Season ◽  
Rio De Janeiro ◽  
Dry Season ◽  
Longitudinal Gradient ◽  
Order Stream ◽  
Surber Sampler ◽  
Janeiro State

Diversity and habitat preference of macroinvertebrates were studied in Macaé River basin, Rio de Janeiro State, Brazil, along its longitudinal gradient. We selected stream reaches corresponding to 1st, 2nd, 4th, 5th and 6th orders. A Surber sampler was used to collect four macroinvertebrates samples of each substrate (sand, litter in pool areas, stones, and litter in riffle areas) during the three sampling periods, defined based on the rain regime: April (end of the rainy season), July (dry season), and October (beginning of the rainy season). We identified 46,431 specimens corresponding to 117 taxa. Analysis of diversity numbers (both for family or genus level) indicated that all insect taxonomic orders had higher numbers on 2nd order stream reach, except for Ephemeroptera, on 4th order. However when considering morph-species taxonomic level, the higher diversity number occurred on 4th order stream. The highest richness and diversity numbers were found at the dry season. Considering habitat preference, both litter in pool areas and litter in riffle areas had the highest faunal richness.

scholarly journals Patterns of Italian high school and university students’ attitudes towards physics: an analysis based on semiotic-cultural perspective

2021 ◽  
Author(s):  
Italo Testa ◽  
Raffaele De Luca Picione ◽  
Umberto Scotti di Uccio
Keyword(s):  
High School ◽  
Cluster Analysis ◽  
University Students ◽  
Correspondence Analysis ◽  
Multiple Correspondence Analysis ◽  
Psychological Theory ◽  
Cultural Perspective ◽  
Undergraduate Level ◽  
Students Attitudes ◽  
And Cluster Analysis

AbstractThe purpose of this study was to analyse Italian high school and university students’ attitudes towards physics using the Semiotic Cultural Psychological Theory (SCPT). In the SCPT framework, attitudes represent how individuals interpret their experience through the mediation of generalized meaning with which they are identified. A view-of-physics questionnaire was used as an instrument to collect data with 1603 high school and university students. Data were analysed through multiple correspondence analysis and cluster analysis. We identified four generalized meanings of physics: (a) interesting and important for society; (b) a quite interesting, but badly taught subject at school and not completely useful for society; (c) difficult to study and irrelevant for society; and (d) a fascinating and protective niche from society. The identified generalized meanings are significantly correlated to the choice to study physics at undergraduate level and to the choice of attending physics-related activities in high school. Implications for research are discussed.

scholarly journals Geographic sharing of ribotype patterns in Enterococcus faecalis for bacterial source tracking

2007 ◽  
Vol 5 (4) ◽  
pp. 539-551 ◽  
Author(s):  
Peter G. Hartel ◽  
Robin L. Kuntz ◽  
Karen Rodgers ◽  
Samuel P. Myoda ◽  
Kerry J. Ritter ◽  
...  
Keyword(s):  
New York ◽  
Enterococcus Faecalis ◽  
Wastewater Treatment Plants ◽  
Geographic Distance ◽  
Similarity Index ◽  
Clonal Diversity ◽  
Mantel Test ◽  
Source Tracking ◽  
Tolerance Level ◽  
Bacterial Source Tracking

The limited host range of Enterococcus faecalis may reduce its clonal diversity and thereby increase its geographic sharing of ribotype patterns. Such sharing would be advantageous for bacterial source tracking (BST). We determined the geographic sharing of ribotype patterns in 752 Ent. faecalis isolates obtained primarily from wastewater treatment plants in Delaware (15 locations; 490 isolates), Georgia (2 locations; 48 isolates), Idaho (1 location; 118 isolates), New York (2 locations; 48 isolates), and Puerto Rico (2 locations; 48 isolates). Isolates were ribotyped with a RiboPrinter. When pooled across all locations and analyzed at a similarity index of 100% and a tolerance level of 1.00%, the 752 Ent. faecalis isolates yielded 652 different ribotypes, of which 429 (66%) were unshared. Even when the matching criterion was relaxed by decreasing the tolerance level from 1% to 10% or lowering the similarity cutoff from 100% to 90%, half or almost half of the ribotypes were unshared. A Mantel test of zero correlation showed no statistically significant correlation between ribotype patterns and geographic distance among the 32 samples (one location at one time) at either the 1.00% (P = 0.91) or 10.00% (P = 0.83) tolerance levels. Therefore, the percentage of ribotype patterns shared between two locations did not increase as the distance between locations decreased. In the case of BST, a permanent host origin database sufficiently large to encompass these ribotype patterns would be time-consuming and expensive to construct.

scholarly journals Limnological study of Piraquara river (Upper Iguaçu basin): spatiotemporal variation of physical and chemical variables and watershed zoning

2003 ◽  
Vol 46 (3) ◽  
pp. 383-394 ◽  
Author(s):  
Paulo Henrique C. Marques ◽  
Haydée Torres de Oliveira ◽  
Eunice da Costa Machado
Keyword(s):  
River Basin ◽  
Oxygen Demand ◽  
Principal Component ◽  
Serra Do Mar ◽  
Spatial Gradients ◽  
Water Composition ◽  
Physical And Chemical Variables ◽  
Nitrite Nitrate ◽  
Physical And Chemical ◽  
Iguaçu River

The Piraquara river basin (Upper Iguaçu River basin - Brazil) was studied as an ecological system throughout a complete seasonal cycle, comprising the rainy and dry season. Analyzes of 16 physical and chemical water variables (dissolved oxygen, biochemical oxygen demand, temperature, pH, conductivity, total nitrogen, total phosphorus, ortophosphates, nitrite, nitrate, ammonium, reagent silicate, total suspended solids, chlorophyll - a, flow velocity and depth) showed correlations between water composition and watershed physiographic features, and the Principal Component Analysis allowed to evidence spatial gradients and seasonal differences. The sampling points were clustered in patches with homogeneous behavior, according to ecologycal concepts: patch 1, with strong influence of Serra do Mar mountains; patch 2, medium course, under Piraquara Dam influence and patch 3, under wetlands influence. Two main factors of serial discontinuity were identified: the Piraquara dam effect and the influence of wetlands. The watershed zoning based on limnological characteristics seeks to subsidize research and biomonitoring for this public springs area.

scholarly journals Water quality and potamoplankton evaluation of the Nile River in Upper Egypt

2015 ◽  
Vol 27 (2) ◽  
pp. 171-190 ◽  
Author(s):  
Ahmed Mohamed El-Otify ◽  
Isaac Agaiby Iskaros
Keyword(s):  
Community Structure ◽  
Zooplankton Community ◽  
Water Level Fluctuations ◽  
Main Stream ◽  
Upper Egypt ◽  
Physical And Chemical Variables ◽  
Different Seasons ◽  
High Current Velocity ◽  
Major Nutrients ◽  
Physical And Chemical

Aim: The composition, abundance, community structure of potamoplankton and major physical and chemical variables of the Nile water in Upper Egypt were investigated to assess its status in different seasons during 2007.MethodsWater samples were collected seasonally during 2007 from six investigated sites from variable depths at levels of 0, 2.5 and 5 m. The area of this investigation is defined as the southern 120 Km of the main stream of the Nile in Upper Egypt (24° 04’ – 25° 00’ latitudes and 32° 51’ – 32° 54’ longitudes), downstream of Aswan Old Dam.ResultsAltogether, 121 potamoplankton species, of which 85 related to phytoplankton and 36 appertaining to zooplankton were recorded. Most numerous phytoplankton were Chlorophyceae (42 species) followed by Bacillariophyceae (30 species). Cyanobacteria and Dinophyceae were less numerous with only 11 and 2 species, respectively. Zooplankton species were mainly belonging to three systematic groups namely; Rotifera (24 species), Copepoda (3 species) and Cladocera (9 species). Besides, other rare zooplankton including Platyhelminthes, Nemata and Ciliophora were sparsely encountered. The main hydrological conditions characterizing the investigated area include water level fluctuations (˂82 - ˃85 m above sea level), relatively high current velocity (0.8 - 1.3 m sec–1) and disposal of wastewater. Plankton populations were variably but rather weakly dependent on the major nutrients due to their excessive availability in accessible form for uptake by the producers. For phytoplankton, the community structure was categorized in relation to temperature, pH, SO42– and Mg2+. For zooplankton, the community structure was categorized in relation to conductivity as well as Mg2+. Sampling intervals were inadequate to demonstrate the existing successional pattern of the Nile potamoplankton community. Alterations in the phytoplankton community structure accompanied changes in water temperature represented by the alternate dominance between diatoms and cyanobacteria, while zooplankton community was always dominated by rotifers. Phytoplankton populations were numerically more abundant in autumn and zooplankton peaked in spring.ConclusionsWastewater disposal restricted the abundance of the Nile zooplankton assemblages mainly due to the numerical decline of Rotifera and Cladocera. Otherwise, wastewater did not exert major limits for phytoplankton. The data obtained in this investigation will be crucial to understand potamoplankton regulation and contribute to the knowledge regarding the Limnology of the Nile basin.

scholarly journals Environmental quality evaluation of lakes in the Rio Grande do Sul coastal plain

2007 ◽  
Vol 50 (4) ◽  
pp. 673-685 ◽  
Author(s):  
Catarina da Silva Pedrozo ◽  
Odete Rocha
Keyword(s):  
Environmental Quality ◽  
Sewage Treatment ◽  
Principal Component ◽  
Organic Pollution ◽  
Physical And Chemical Variables ◽  
Environmental Element ◽  
Different Characteristics ◽  
Physical And Chemical ◽  
The Town

The purpose of the present work was to evaluate the environmental quality of Marcelino, Pinguela, Peixoto, Palmital, Malvas and Do Passo lakes, interconnected by canals and located in the district of Osório, RS. In this context, 29 physical and chemical variables were analyzed with sampling carried out in January, May, July and October 1997 to verify the environmental quality of the system and the existence of a gradient of quality. Canonical Analysis was applied to the data of all environmental variables measured, and showed that the lakes had different characteristics as a consequence of the organic pollution received. Marcelino lake received continuous input of organic matter from the sewage treatment works in the town of Osório, whereas Peixoto, Pinguela, Palmital, Malvas and Do Passo lakes resembled other water bodies described in the region, not showing, so far, signs of degradation caused by the input of effluents. Principal Component Analysis selected environmental element were directly linked to organic pollution, that reflected sequential non-recent effects of contamination.

scholarly journals A Study of Zooplankton Community in Dukan Lake, Kurdistan Region-Iraq, with a New Record of Craspedacusta sowerbii Lankester (1880) Medusa (Cnidaria: Hydrozoa)

2017 ◽  
Vol 14 (4) ◽  
pp. 735-741 ◽  
Author(s):  
Baghdad Science Journal
Keyword(s):  
Similarity Index ◽  
Chemical Properties ◽  
Zooplankton Community ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Alkaline Side ◽  
Physical And Chemical ◽  
First Time ◽  
Jaccard's Similarity Index ◽  
And Chemical Properties

A study of Zooplankton community has been carried out at four selected sites on Dukan Lake. Samples of water and zooplankton were collected monthly for the period from July 2015 to February 2016. Some physical and chemical properties of water were studied and the results showed that the air temperature were ranged from 0 to 36.16 °C, water temperature ranged from 2.83 to 34.66 °C, hydrogen ion concentration of studied sites were found to lie in alkaline side, it was ranged between 6.87 to 8.57, electrical conductivity ranged from 190.79 to 850.08 µs.cm­¹, turbidity ranged from 0.9-7.7 NTU, and dissolved oxygen from 3.3 to 6.8 mg.l-¹ while BOD5 were ranged from 0.53 to 34.66 mg.l-¹. Concerning to the zooplankton, 37 species were identified which belonged to Cladocera (48.38%), Copepod (43.28%), Rotifera (8.23%), Targigrada (0.08%) and Cnidaria (0.1%). The medusa of Craspedacusta sowerbii Lankester (1880) was recorded for the first time in Iraq. Regarding to zooplankton community, rotifer were ranged between 0 to 690.91 ind.m-3, Copepoda from 54.55 to 5927.27 ind.m-3 and Cladocera ranged from 18.18 to 6072.73 ind.m-3. According to Shanon-Weiner index, species diversity for zooplankton invertebrates was ranged from 0.325 to 1.091 bits/ind. Jaccard’s similarity index showed that the highest similarity was recorded between site (1) and site (4) with 40.74%.

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