scholarly journals The role of abiotic and biotic environmental factors in shaping epiphyton on common reed in shallow, hydrologically transformed, temperate lakes

2018 ◽  
pp. 18 ◽  
Author(s):  
Magdalena Toporowska ◽  
Jacek Rechulicz ◽  
Małgorzata Adamczuk ◽  
Michał Niedźwiecki
Keyword(s):  
Environmental Parameters ◽  
Eutrophic Lake ◽  
Common Reed ◽  
Grazing Pressure ◽  
Biomass Composition ◽  
Water Level Fluctuations ◽  
Significant Variable ◽  
Eutrophic Lakes ◽  
Epiphytic Algae

Epiphytic algae are an important group of organisms involved in primary productivity, nutrient cycling, and energy transfer in littoral food webs. However, multifactorial studies conducted on epiphyton on the same substrate across a spectrum of environmental parameters are very limited. Here, we present first complex field study on the role of abiotic and biotic factors in shaping the species richness, diversity, abundance, and biomass composition of epiphyton on common reed in four shallow lakes with different trophic status, water and fish management, and the abundance and structure of potential algal grazers: littoral crustaceans and fish. The obtained results revealed that the algal taxa richness was the lowest in the hypertrophic lake and the highest in the meso-eutrophic lake. Epiphyton abundance (predominated by pennate diatoms) and biomass were found to be the highest in eutrophic water bodies. Biomass consisted primarily of diatoms, but we found the seasonal predominance of filamentous Chlorophyta (in the eutrophic lakes) and Chlorophyceae (in the meso-eutrophic lake). Redundancy analysis (RDA) showed that the frequency of water level fluctuations was the most significant variable in the composition of epiphyton. RDA also revealed the importance of grazing pressure of fish. Thus, in hydrologically transformed lakes, man-made factors may be of great relevance in the development of epiphytic algae.

scholarly journals Grazing pressure-induced shift in planktonic bacterial communities with the dominance of acIII-A1 actinobacterial lineage in soda pans

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Attila Szabó ◽  
Kristóf Korponai ◽  
Boglárka Somogyi ◽  
Balázs Vajna ◽  
Lajos Vörös ◽  
...  
Keyword(s):  
Bacterial Communities ◽  
Algal Blooms ◽  
Ionic Composition ◽  
Extreme Environments ◽  
Grazing Pressure ◽  
Water Level Fluctuations ◽  
Organic Carbon Concentration ◽  
High Turbidity ◽  
Physical And Chemical

AbstractAstatic soda pans of the Pannonian Steppe are unique environments with respect to their multiple extreme physical and chemical characteristics (high daily water temperature fluctuation, high turbidity, alkaline pH, salinity, polyhumic organic carbon concentration, hypertrophic state and special ionic composition). However, little is known about the seasonal dynamics of the bacterial communities inhabiting these lakes and the role of environmental factors that have the main impact on their structure. Therefore, two soda pans were sampled monthly between April 2013 and July 2014 to reveal changes in the planktonic community. By late spring in both years, a sudden shift in the community structure was observed, the previous algae-associated bacterial communities had collapsed, resulting the highest ratio of Actinobacteria within the bacterioplankton (89%, with the dominance of acIII-A1 lineage) ever reported in the literature. Before these peaks, an extremely high abundance (> 10,000 individuum l−1) of microcrustaceans (Moina brachiata and Arctodiaptomus spinosus) was observed. OTU-based statistical approaches showed that in addition to algal blooms and water-level fluctuations, zooplankton densities had the strongest effect on the composition of bacterial communities. In these extreme environments, this implies a surprisingly strong, community-shaping top-down role of microcrustacean grazers.

scholarly journals Grazing pressure-induced shift in planktonic bacterial communities with the dominance of acIII-A1 actinobacterial lineage in soda pans

2020 ◽  
Author(s):  
Attila Szabó ◽  
Kristóf Korponai ◽  
Boglárka Somogyi ◽  
Balázs Vajna ◽  
Lajos Vörös ◽  
...  
Keyword(s):  
Bacterial Communities ◽  
Algal Blooms ◽  
Ionic Composition ◽  
Extreme Environments ◽  
Grazing Pressure ◽  
Water Level Fluctuations ◽  
Organic Carbon Concentration ◽  
High Turbidity ◽  
Physical And Chemical

AbstractAstatic soda pans of the Pannonian Steppe are unique environments with respect to their multiple extreme physical and chemical characteristics (high daily water temperature fluctuation, high turbidity, alkaline pH, salinity, polyhumic organic carbon concentration, hypertrophic state and special ionic composition). However, little is known about the seasonal dynamics of the bacterial communities inhabiting these lakes and the role of environmental factors that have the main impact on their structure. Therefore, two soda pans were sampled monthly between April 2013 and July 2014 to reveal changes in the planktonic community. By late spring in both years, a sudden shift in the community structure was observed, the previous algae-associated bacterial communities had collapsed, resulting the highest ratio of actinobacteria within the bacterioplankton (89%, with the dominance of acIII-A1 lineage) ever reported in the literature. Before these peaks, an extremely high abundance (>10,000 individuum l−1) of microcrustaceans (Moina and Arctodiaptomus) was observed. OTU-based statistical approaches showed that in addition to algal blooms and water-level fluctuations, zooplankton densities had the strongest effect on the composition of bacterial communities. In these extreme environments, this implies a surprisingly strong, community-shaping top-down role of microcrustacean grazers.

scholarly journals Seagrass: A Dynamic System

2021 ◽  
Author(s):  
◽  
Alison Duncan
Keyword(s):  
Nutrient Enrichment ◽  
Abiotic Factors ◽  
Grazing Pressure ◽  
Small Scale ◽  
Nutrient Loads ◽  
Negative Effects ◽  
Epiphytic Algae ◽  
Seagrass Meadows ◽  
A Site

<p>Small herbivorous invertebrates consume algal epiphytes, reducing negative effects (e.g. shading) on seagrass. Much research to date has focused on crustacean grazers, and comparatively little on gastropods. The aim of this research was to 1) examine seasonal and spatial variation in seagrass and associated gastropods in a large, tidal estuary and 2) examine the response of seagrass and epiphytic algae to nutrient enrichment and grazing pressure in a laboratory experiment.  Surveys were conducted in summer and winter of 2016 to assess the seasonal fluctuations in the associated gastropods and relationships with seagrass and epiphyte biomass within three sites in the Porirua Harbour. Seagrass, gastropods and epiphytic algae showed seasonal trends, including evidence of a loss of grazer control on epiphytes during winter. Potamopyrgus estuarinus, Notoacmea scapha, Diloma spp. and Micrelenchus spp. were the dominant gastropod grazers in the system in both seasons. The gastropod assemblage and seagrass characteristics differed between sites, likely in response to small scale differences in abiotic factors.  Seagrass from Elsdon (a site with elevated nutrient levels) and Browns Bay (a relatively pristine site) were used to investigate the role of select grazers and nutrient enrichment on epiphyte and seagrass growth. Nutrient treatments represented nitrate and phosphate concentrations of Elsdon (High), a 20% increase (High+) and a control (no addition). Little evidence was found for epiphyte regulation by gastropods, nor did epiphyte loads increase with nutrient addition. Seagrass from Browns Bay responded more strongly to High+ treatments than that of Elsdon. The results suggest that seagrass from Elsdon is adapted to the site’s high nutrient loads, where seagrass from Browns Bay is not. The results of this thesis support prior research findings of high variation in seagrass over a small scale, and adds to the currently lacking information on the role of micro-grazers in New Zealand’s seagrass meadows.</p>

scholarly journals Seagrass: A Dynamic System

2021 ◽  
Author(s):  
◽  
Alison Duncan
Keyword(s):  
Nutrient Enrichment ◽  
Abiotic Factors ◽  
Grazing Pressure ◽  
Small Scale ◽  
Nutrient Loads ◽  
Negative Effects ◽  
Epiphytic Algae ◽  
Seagrass Meadows ◽  
A Site

<p>Small herbivorous invertebrates consume algal epiphytes, reducing negative effects (e.g. shading) on seagrass. Much research to date has focused on crustacean grazers, and comparatively little on gastropods. The aim of this research was to 1) examine seasonal and spatial variation in seagrass and associated gastropods in a large, tidal estuary and 2) examine the response of seagrass and epiphytic algae to nutrient enrichment and grazing pressure in a laboratory experiment.  Surveys were conducted in summer and winter of 2016 to assess the seasonal fluctuations in the associated gastropods and relationships with seagrass and epiphyte biomass within three sites in the Porirua Harbour. Seagrass, gastropods and epiphytic algae showed seasonal trends, including evidence of a loss of grazer control on epiphytes during winter. Potamopyrgus estuarinus, Notoacmea scapha, Diloma spp. and Micrelenchus spp. were the dominant gastropod grazers in the system in both seasons. The gastropod assemblage and seagrass characteristics differed between sites, likely in response to small scale differences in abiotic factors.  Seagrass from Elsdon (a site with elevated nutrient levels) and Browns Bay (a relatively pristine site) were used to investigate the role of select grazers and nutrient enrichment on epiphyte and seagrass growth. Nutrient treatments represented nitrate and phosphate concentrations of Elsdon (High), a 20% increase (High+) and a control (no addition). Little evidence was found for epiphyte regulation by gastropods, nor did epiphyte loads increase with nutrient addition. Seagrass from Browns Bay responded more strongly to High+ treatments than that of Elsdon. The results suggest that seagrass from Elsdon is adapted to the site’s high nutrient loads, where seagrass from Browns Bay is not. The results of this thesis support prior research findings of high variation in seagrass over a small scale, and adds to the currently lacking information on the role of micro-grazers in New Zealand’s seagrass meadows.</p>

scholarly journals Prioritizing and Analyzing the Role of Climate and Urban Parameters in the Confirmed Cases of COVID-19 Based on Artificial Intelligence Applications

2020 ◽  
Vol 17 (10) ◽  
pp. 3730 ◽  
Author(s):  
Sina Shaffiee Haghshenas ◽  
Behrouz Pirouz ◽  
Sami Shaffiee Haghshenas ◽  
Behzad Pirouz ◽  
Patrizia Piro ◽  
...  
Keyword(s):  
Artificial Intelligence ◽  
Infectious Disease ◽  
Relative Humidity ◽  
Cost Function ◽  
Selection Process ◽  
Environmental Parameters ◽  
Pso Algorithm ◽  
Data Set ◽  
De Algorithm

Nowadays, an infectious disease outbreak is considered one of the most destructive effects in the sustainable development process. The outbreak of new coronavirus (COVID-19) as an infectious disease showed that it has undesirable social, environmental, and economic impacts, and leads to serious challenges and threats. Additionally, investigating the prioritization parameters is of vital importance to reducing the negative impacts of this global crisis. Hence, the main aim of this study is to prioritize and analyze the role of certain environmental parameters. For this purpose, four cities in Italy were selected as a case study and some notable climate parameters—such as daily average temperature, relative humidity, wind speed—and an urban parameter, population density, were considered as input data set, with confirmed cases of COVID-19 being the output dataset. In this paper, two artificial intelligence techniques, including an artificial neural network (ANN) based on particle swarm optimization (PSO) algorithm and differential evolution (DE) algorithm, were used for prioritizing climate and urban parameters. The analysis is based on the feature selection process and then the obtained results from the proposed models compared to select the best one. Finally, the difference in cost function was about 0.0001 between the performances of the two models, hence, the two methods were not different in cost function, however, ANN-PSO was found to be better, because it reached to the desired precision level in lesser iterations than ANN-DE. In addition, the priority of two variables, urban parameter, and relative humidity, were the highest to predict the confirmed cases of COVID-19.

Effects of Fe addition on sediment P dynamics in a eutrophic lake

2021 ◽  
Author(s):  
Melanie Münch ◽  
Rianne van Kaam ◽  
Karel As ◽  
Stefan Peiffer ◽  
Gerard ter Heerdt ◽  
...  
Keyword(s):  
Water Quality ◽  
Organic Matter ◽  
Surface Water ◽  
Water Column ◽  
Sediment Cores ◽  
Surface Water Quality ◽  
Water Interface ◽  
Eutrophic Lakes ◽  
Fe Addition

&lt;p&gt;The decline of surface water quality due to excess phosphorus (P) input is a global problem of increasing urgency. Finding sustainable measures to restore the surface water quality of eutrophic lakes with respect to P, other than by decreasing P inputs, remains a challenge. The addition of iron (Fe) salts has been shown to be effective in removing dissolved phosphate from the water column of eutrophic lakes. However, the resulting changes in biogeochemical processes in sediments as well as the long-term effects of Fe additions on P dynamics in both sediments and the water column are not well understood.&lt;/p&gt;&lt;p&gt;In this study, we assess the impact of past Fe additions on the sediment P biogeochemistry of Lake Terra Nova, a well-mixed shallow peat lake in the Netherlands. The Fe-treatment in 2010 efficiently reduced P release from the sediments to the surface waters for 6 years. Since then, the internal sediment P source in the lake has been increasing again with a growing trend over the years.&lt;/p&gt;&lt;p&gt;In 2020, we sampled sediments at three locations in Terra Nova, of which one received two times more Fe during treatment than the other two. Sediment cores from all sites were sectioned under oxygen-free conditions. Both the porewaters and sediments were analysed for their chemical composition, with sequential extractions providing insight into the sediment forms of P and Fe. Additional sediment cores were incubated under oxic and anoxic conditions and the respective fluxes of P and Fe across the sediment water interface were measured.&lt;/p&gt;&lt;p&gt;The results suggest that Fe and P dynamics in the lake sediments are strongly coupled. We also find that the P dynamics are sensitive to the amount of Fe supplied, even though enhanced burial of P in the sediment was not detected. The results of the sequential extraction procedure for P, which distinguishes P associated with humic acids and Fe oxides, as well as reduced flux of Fe(II) across the sediment water interface in the anoxic incubations, suggest a major role of organic matter in the interaction of Fe and P in these sediments.&lt;/p&gt;&lt;p&gt;Further research will include investigations of the role of organic matter and sulphur in determining the success of Fe-treatment in sequestering P in lake sediments. Based on these data in combination with reactive transport modelling we aim to constrain conditions for successful lake restoration through Fe addition.&lt;/p&gt;

scholarly journals Genetic Diversity of Small Eukaryotes in Lakes Differing by Their Trophic Status

2005 ◽  
Vol 71 (10) ◽  
pp. 5935-5942 ◽  
Author(s):  
Marie Lefranc ◽  
Aurélie Thénot ◽  
Cécile Lepère ◽  
Didier Debroas
Keyword(s):  
Trophic Status ◽  
Eutrophic Lake ◽  
Rrna Genes ◽  
Eutrophic Lakes ◽  
Massif Central ◽  
Operational Taxonomic Units ◽  
Single Clone ◽  
18S Rrna Genes ◽  
Lake Pavin ◽  
Environmental Sequences

ABSTRACT Small eukaryotes, cells with a diameter of less than 5 μm, are fundamental components of lacustrine planktonic systems. In this study, small-eukaryote diversity was determined by sequencing cloned 18S rRNA genes in three libraries from lakes of differing trophic status in the Massif Central, France: the oligotrophic Lake Godivelle, the oligomesotrophic Lake Pavin, and the eutrophic Lake Aydat. This analysis shows that the least diversified library was in the eutrophic lake (12 operational taxonomic units [OTUs]) and the most diversified was in the oligomesotrophic lake (26 OTUs). Certain groups were present in at least two ecosystems, while the others were specific to one lake on the sampling date. Cryptophyta, Chrysophyceae, and the strictly heterotrophic eukaryotes, Ciliophora and fungi, were identified in the three libraries. Among the small eukaryotes found only in two lakes, Choanoflagellida and environmental sequences (LKM11) were not detected in the eutrophic system whereas Cercozoa were confined to the oligomesotrophic and eutrophic lakes. Three OTUs, linked to the Perkinsozoa, were detected only in the Aydat library, where they represented 60% of the clones of the library. Chlorophyta and Haptophyta lineages were represented by a single clone and were present only in Godivelle and Pavin, respectively. Of the 127 clones studied, classical pigmented organisms (autotrophs and mixotrophs) represented only a low proportion regardless of the library's origin. This study shows that the small-eukaryote community composition may differ as a function of trophic status; certain lineages could be detected only in a single ecosystem.

scholarly journals Earth observation for monitoring and mapping of cyanobacteria blooms. Case studies on five Italian lakes

2016 ◽  
Vol 76 (s1) ◽  
Author(s):  
Mariano Bresciani ◽  
Claudia Giardino ◽  
Rosaria Lauceri ◽  
Erica Matta ◽  
Ilaria Cazzaniga ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Algal Blooms ◽  
Remote Sensing Data ◽  
Late Summer ◽  
Eutrophic Lake ◽  
Cyanobacterial Blooms ◽  
Landsat 8 ◽  
Negative Effects ◽  
Eutrophic Lakes ◽  
Chl A

Cyanobacterial blooms occur in many parts of the world as a result of entirely natural causes or human activity. Due to their negative effects on water resources, efforts are made to monitor cyanobacteria dynamics. This study discusses the contribution of remote sensing methods for mapping cyanobacterial blooms in lakes in northern Italy. Semi-empirical approaches were used to flag scum and cyanobacteria and spectral inversion of bio-optical models was adopted to retrieve chlorophyll-a (Chl-a) concentrations. Landsat-8 OLI data provided us both the spatial distribution of Chl-a concentrations in a small eutrophic lake and the patchy distribution of scum in Lake Como. ENVISAT MERIS time series collected from 2003 to 2011 enabled the identification of dates when cyanobacterial blooms affected water quality in three small meso-eutrophic lakes in the same region. On average, algal blooms occurred in the three lakes for about 5 days a year, typically in late summer and early autumn. A suite of hyperspectral sensors on air- and space-borne platforms was used to map Chl-a concentrations in the productive waters of the Mantua lakes, finding values in the range of 20 to 100 mgm-3. The present findings were obtained by applying state of the art of methods applied to remote sensing data. Further research will focus on improving the accuracy of cyanobacteria mapping and adapting the algorithms to the new-generation of satellite sensors.

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