The Experts below are selected from a list of 1611 Experts worldwide ranked by ideXlab platform
Jordi Catalan - One of the best experts on this subject based on the ideXlab platform.
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Deciphering chrysophyte responses to climate seasonality
Journal of Paleolimnology, 2011Co-Authors: Sergi Pla-rabes, Jordi CatalanAbstract:Climate change involves alterations in seasonality as well as shifts in mean annual temperature. Cold temperate lakes show strong seasonality, with winter ice cover and alternating mixing and stratification periods during the ice-free season. These physical changes are ultimately related to seasonal weather variation and also drive annual phytoplankton succession. Therefore, phytoplankton remains in lake sediment records are potentially useful for reconstructing past seasonal climate signals. With the exception of investigations on varved sediments, however, little research has been carried out on the subject. Here we present two lines of evidence demonstrating that chrysophyte stomatocysts can be useful for inferring past climatic seasonality. First, we show that marked seasonal stomatocyst replacement is related to periods of the main physical processes in the lake. Second, using instrumental climate data and microfossils in sediment cores, we show that two main components of stomatocyst variability over the last ~150 years are related to seasonal fluctuations. The first of these components is related to stomatocysts present during summer stratification that respond to general warming trends, particularly in July and August. The second component relates to stomatocysts typically present in the spring and autumn mixing periods. Numbers of these two stomatocyst types vary inversely in response to variation in spring (April–May) temperatures. The number of stomatocyst types affected by spring temperatures is much greater than those related to summer temperatures. We provide evidence that chrysophyte stomatocysts are an excellent proxy for spring air temperature reconstructions, with little influence from summer or general annual trends. We also show that with relatively little effort, it is possible to categorise the chrysophyte stomatocyst assemblage of a lake to carry out detailed investigation of the record of seasonal changes preserved within the sediment.
Astrid Voigt - One of the best experts on this subject based on the ideXlab platform.
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ecological impacts of fluridone and copper sulphate in catfish aquaculture ponds
Environmental Toxicology and Chemistry, 2016Co-Authors: Annie P Jacob, Roman P Lanno, David A Culver, Astrid VoigtAbstract:Fluridone and copper sulphate are often used for controlling macrophytes and algae in aquaculture ponds. The present study examined the ecological effects of these chemicals on macrophyte, phytoplankton, and zooplankton biomass, plankton community structure, water quality parameters, and fish survival and yield in catfish culture ponds using a randomized complete block design. The estimated half-life of fluridone in the individual ponds ranged from 1.6 to 10.8 d. Free copper ion activity in ponds treated with copper sulphate was dynamic, ranging from pCu of 7.7 to 8.9 after each application and decreasing to ∼12 (1 × 10−12M) within a week after each application, approaching observed values in control ponds (pCu = 12.3 to 13.4). No difference in macrophyte biomass was observed among treatments. Fluridone and copper treatments elicited different responses within the phytoplankton community. Copper treatments reduced Cyanophyta biomass, but increased biomass of more tolerant taxa among the Chlorophyta and Chrysophyta. Fluridone treatments reduced total phytoplankton biomass including Cyanophyta and increased the sensitivity of Chlorophyta and Chrysophyta to copper. Copper also affected zooplankton community composition due to direct toxic effects on sensitive zooplankton taxa (e.g., Cladocera), whereas Copepoda biomass in copper-treated ponds exceeded that in controls. Catfish survival and yield were not significantly different among treatments. The results of the present study suggest that fluridone and copper interact at realistic application rates, increasing the ability to control algae compared to treatments where they are applied alone. This article is protected by copyright. All rights reserved
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Ecological impacts of fluridone and copper sulphate in catfish aquaculture ponds.
Environmental Toxicology and Chemistry, 2016Co-Authors: Annie P Jacob, Roman P Lanno, David A Culver, Astrid VoigtAbstract:Fluridone and copper sulphate are often used for controlling macrophytes and algae in aquaculture ponds. The present study examined the ecological effects of these chemicals on macrophyte, phytoplankton, and zooplankton biomass; plankton community structure; water quality parameters; and fish survival and yield in catfish culture ponds using a randomized complete block design. The estimated half-life of fluridone in the individual ponds ranged from 1.6 d to 10.8 d. Free copper ion activity in ponds treated with copper sulphate was dynamic, ranging from pCu of 7.7 to 8.9 after each application and decreasing to approximately 12 (1 × 10(-12) M) within 1 wk after each application, approaching observed values in control ponds (pCu = 12.3-13.4). No difference in macrophyte biomass was observed among treatments. Fluridone and copper treatments elicited different responses within the phytoplankton community. Copper treatments reduced Cyanophyta biomass but increased biomass of more tolerant taxa among the Chlorophyta and Chrysophyta. Fluridone treatments reduced total phytoplankton biomass including Cyanophyta and increased the sensitivity of Chlorophyta and Chrysophyta to copper. Copper also affected zooplankton community composition as a result of direct toxic effects on sensitive zooplankton taxa (e.g., Cladocera), whereas Copepoda biomass in copper-treated ponds exceeded that in controls. Catfish survival and yield were not significantly different among treatments. The results of the present study suggest that fluridone and copper interact at realistic application rates, increasing the ability to control algae compared with treatments where they are applied alone.
Sergi Pla-rabes - One of the best experts on this subject based on the ideXlab platform.
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Deciphering chrysophyte responses to climate seasonality
Journal of Paleolimnology, 2011Co-Authors: Sergi Pla-rabes, Jordi CatalanAbstract:Climate change involves alterations in seasonality as well as shifts in mean annual temperature. Cold temperate lakes show strong seasonality, with winter ice cover and alternating mixing and stratification periods during the ice-free season. These physical changes are ultimately related to seasonal weather variation and also drive annual phytoplankton succession. Therefore, phytoplankton remains in lake sediment records are potentially useful for reconstructing past seasonal climate signals. With the exception of investigations on varved sediments, however, little research has been carried out on the subject. Here we present two lines of evidence demonstrating that chrysophyte stomatocysts can be useful for inferring past climatic seasonality. First, we show that marked seasonal stomatocyst replacement is related to periods of the main physical processes in the lake. Second, using instrumental climate data and microfossils in sediment cores, we show that two main components of stomatocyst variability over the last ~150 years are related to seasonal fluctuations. The first of these components is related to stomatocysts present during summer stratification that respond to general warming trends, particularly in July and August. The second component relates to stomatocysts typically present in the spring and autumn mixing periods. Numbers of these two stomatocyst types vary inversely in response to variation in spring (April–May) temperatures. The number of stomatocyst types affected by spring temperatures is much greater than those related to summer temperatures. We provide evidence that chrysophyte stomatocysts are an excellent proxy for spring air temperature reconstructions, with little influence from summer or general annual trends. We also show that with relatively little effort, it is possible to categorise the chrysophyte stomatocyst assemblage of a lake to carry out detailed investigation of the record of seasonal changes preserved within the sediment.
John Onwuteaka - One of the best experts on this subject based on the ideXlab platform.
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SPATIAL DISTRIBUTION DYNAMICS OF PHYTOPLANKTON IN THE NON-TIDAL AND TIDAL ZONE OF WOJI CREEK IN NIGER DELTA, NIGERIA.
2014Co-Authors: John OnwuteakaAbstract:Biweekly phytoplankton collection of four months duration from six stations of Woji Creek and Bonny estuary in Rivers State Nigeria was used to study the occurrence pattern along a transition zone between estuarine and freshwater habitats. The presence-absence data showed a rich composition of 150 species of algae distributed in 5 classes of macroalgae namely the Bacillariophyta, Cyanophyta, Chlorophyta, Chrysophyta and the Euglenophyta and 54 genera. The contingency analysis in SAS JMP statistics was used to explore the presence-absence relationship between the tidal and non-tidal stations for each of the macro algae class identified in the dry and wet seasons. Among the five classes, the Bacillariophyta and the Chrysophyta had no significant independence (p 0.10) in occurrence. The results show evidence of a spatial distribution of the phytoplankton is that support an ecocline concept rather than an ecotone despite the differences in salinity between the tidal and non-tidal stations. The study provides a rapid assessment and screening tool of environmental change through a taxonomic diversity of the dominant Bacillariophyta and Cyanophyta and through the identification of the ubiquitous and the non-ubiquitous species from the Bacillariophyta, Cyanophyta, Chlorophyta, and the Euglenophyta.
Xie Shulian - One of the best experts on this subject based on the ideXlab platform.
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College on Paraphysomonadaceae(Chrysophyta) in China
Journal of Hebei Normal University, 2012Co-Authors: Xie ShulianAbstract:Sixteen species of Paraphysomonadaceae(Chrysophyta) from China are recorded.They are Paraphysomonas circumvallata,P.imperforate,P.vestita,P.gladiate,P.takahashii,P.runcinifera,P.punctata,P.butcheri,P.diademifera,Chrysosphaerella annulata,C.septispina,C.brevispina,C.coronacircumspina,Spiniferomonus bourrellii,S.trioralis and S.takahashyi.
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new records of mallomonas Chrysophyta from shanxi province china
Arid Zone Research, 2012Co-Authors: Feng Jia, Xie ShulianAbstract:The genus Mallomonas belongs to Synurales,Synurophyceae,Chrysophyta,it was created by Perty in 1852 and reported as one of the largest genera in Chrysophyta.Algae of the genus including solotary colored monads with the cells covered with silica scales were regularly arranged as imbricate or armor shape,or freely.Some scales bear bristles and some do not.They were considered as the most important taxonomic characters for species determination and species taxonomy.Because of their narrow ecological optimum,the species of Mallomonas were considered as the valuable bio-indicators of both recent and historical environments,especially in paleolimnology.Based on the study of specimens and literatures,9 species of Mallomonas in Shanxi Province are reported in this paper for the first time,and they are M.caudata,M.oviformis,M.insignis,M.striata,M.areolata,M.elongata,M.tonsurata,M.costata and M.acaroides.These new records make the materials about algae in Shanxi Province be abundant.
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Study on Stylococcaceae(Chrysophyta) in China
Journal of Shanxi Normal University, 2011Co-Authors: Xie ShulianAbstract:Ten species of Stylococcaceae(Chrysophyta) from China are reported.They are Lagynion ampullaceum,L.globosum var.ellipticum,L.urceolatum,L.macrotrachelum,L.scherffelii,Chrysopyxis stenostoma,C.iwanoff,C.bipes,Bitrichia chodatii and B.phaseolus.
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Dinobryonaceae(Chrysophyta) in China
Journal of Shanxi University, 2011Co-Authors: Xie ShulianAbstract:Ninteen species and one variety of Dinobryonaceae(Chrysophyta) from China are reported.They are Dinobryon spirale,D.tabelleriae,D.cylindricum,D.divergens,D.sociale,D.elegantissimum,D.bavaricum,D.sertularia,Chrysococcus diaphanous,Ch.rufescens,Kephyrion boreale,K.impletum,K.ovale,K.mastigophorum K.littorale,K.planctonicum,Pseudokephyrion entzii,P.undulatissimum var.rhombeum,Epipyxis utriculus and Stokesiella lepteca.