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Abstract Background Algae play important roles in urban river ecosystems and are the cornerstones of most water quality monitoring programs. Thus, a better understanding of algal community dynamics is needed to support sustainable management of water resources in urban rivers. Results In this study, we quantified the seasonal variations in planktonic and periphytic algal community structure in the highly urban Fenhe River and identified environmental factors affecting algal community structure and diversity. We monitored planktonic (drifting) and periphytic (attached) algal communities in the Taiyuan section of the Fenhe River over one year. The results indicated that Cyanophyta was the dominant phylum in both communities, followed by Bacillariophyta and Chlorophyta. Significant differences were observed in the composition of the planktonic and periphytic algal communities. In particular, the periphytic algal community was more diverse than the planktonic community. Water temperature and pH were the main environmental factors affecting planktonic and periphytic algal community structure, respectively, while nutrients were the most significant factor affecting planktonic and periphytic algal diversity. Ecological modeling indicated that the variations in the algal communities of the Fenhe River are mainly driven by stochastic processes. A co-occurrence network developed for the communities displayed positive interactions between the planktonic and periphytic algae. Conclusions These findings deepen our understanding of the seasonal interaction between planktonic and periphytic algae and the driving factors affecting community structure in the Fenhe River. They also provide a theoretical basis for the managing and protecting water resources in urban river ecosystems.

Background: Algae play important roles in urban river ecosystems and are the cornerstones of most water quality monitoring programs. Thus, a better understanding of algal community dynamics is needed to support sustainable management of water resources in urban rivers. Results: In this study, we quantified the seasonal variations in planktonic and periphytic algal community structure in the highly urban Fenhe River and identified environmental factors affecting algal community structure and diversity. We monitored planktonic (drifting) and periphytic (attached) algal communities in the Taiyuan section of the Fenhe River over one year. The results indicated that Cyanophyta was the dominant phylum in both communities, followed by Bacillariophyta and Chlorophyta. Significant differences were observed in the composition of the planktonic and periphytic algal communities. In particular, the periphytic algal community was more diverse than the planktonic community. Water temperature and pH were the main environmental factors affecting planktonic and periphytic algal community structure, respectively, while nutrients were the most significant factor affecting planktonic and periphytic algal diversity. Ecological modeling indicated that the variations in the algal communities of the Fenhe River are mainly driven by stochastic processes. A co-occurrence network developed for the communities displayed positive interactions between the planktonic and periphytic algae. Conclusions: These findings deepen our understanding of the seasonal interaction between planktonic and periphytic algae and the driving factors affecting community structure in the Fenhe River. They also provide a theoretical basis for the managing and protecting water resources in urban river ecosystems. [ABSTRACT FROM AUTHOR]

Periphytic algal colonization is common in aquatic systems, but its interspecific competition remains poorly understood. In order to fill the gap, the process of periphytic algal colonization in the Middle Route of the South to North Water Diversion Project was studied. The results showed that the process was divided into three stages: the initial colonization stage (T1, 3–6 days), community formation stage (T2, 12–18 days) and primary succession stage (T3, 24–27 days). In T1, the dominant species were Diatoma vulgaris (Bory), Navicula phyllepta (Kützing) and Fragilaria amphicephaloides (Lange-Bertalot) belonging to Heterokontophyta; these species boasted wide niche widths (NWs), low niche overlap (NO) and low ecological response rates (ERRs). In T2, the dominant species were Diatoma vulgaris, Cymbella affinis (Kützing), Navicula phyllepta, Fragilaria amphicephaloides, Gogorevia exilis (Kützing), Melosira varians (C.Agardh), Phormidium willei (N.L.Gardner) and Cladophora rivularis (Kuntze). These species displayed wider NWs, lower NO, and lower ERRs than those in T1. In T3, the dominant species were Diatoma vulgaris, Cymbella affinis, Navicula phyllepta, Fragilaria amphicephaloides, Achnanthes exigu (Grunow), etc. Among them, Heterokontophyta such as Diatoma vulgaris and Cymbella affinis had a competitive advantage based on NWs and ERRs. Cyanobacteria like Phormidium willei lost their dominant status due to the narrower NW and the increased NO. It could be concluded the interspecific competition became fiercer and shaped the colonization process; this study will be helpful in understanding the colonization of periphytic algal communities. [ABSTRACT FROM AUTHOR]

[Objective] The biological characteristics of different attached algae were determined and the relation between water quality indicators and algae biological characteristics were analyzed in order to provide scientific support for screening scientifically reasonable attached substrates and enriching the growth of attached algae. [Methods] The biological characteristics of algae attached to three different building material substrates (granite, polyethylene mesh, wood) were analyzed using simulation experiments. The types of attached substrates having good effects and easy resource utilization were selected. [Results] The periphytic algae communities attached to granite and wood substrates were more stable, and had better biological characteristics and more functional algae species, and thereby were more conducive to providing an ecological effect of periphytic algae in the water environment. [Conclusion] The granite substrate was considered to be the most suitable substrate among the three tested substrates because of its ready availability and ease of use.

Periphytic algal colonization is common in aquatic systems, but its interspecific competition remains poorly understood. In order to fill the gap, the process of periphytic algal colonization in the Middle Route of the South to North Water Diversion Project was studied. The results showed that the process was divided into three stages: the initial colonization stage (T1, 3–6 days), community formation stage (T2, 12–18 days) and primary succession stage (T3, 24–27 days). In T1, the dominant species were Diatoma vulgaris (Bory), Navicula phyllepta (Kützing) and Fragilaria amphicephaloides (Lange-Bertalot) belonging to Heterokontophyta; these species boasted wide niche widths (NWs), low niche overlap (NO) and low ecological response rates (ERRs). In T2, the dominant species were Diatoma vulgaris, Cymbella affinis (Kützing), Navicula phyllepta, Fragilaria amphicephaloides, Gogorevia exilis (Kützing), Melosira varians (C.Agardh), Phormidium willei (N.L.Gardner) and Cladophora rivularis (Kuntze). These species displayed wider NWs, lower NO, and lower ERRs than those in T1. In T3, the dominant species were Diatoma vulgaris, Cymbella affinis, Navicula phyllepta, Fragilaria amphicephaloides, Achnanthes exigu (Grunow), etc. Among them, Heterokontophyta such as Diatoma vulgaris and Cymbella affinis had a competitive advantage based on NWs and ERRs. Cyanobacteria like Phormidium willei lost their dominant status due to the narrower NW and the increased NO. It could be concluded the interspecific competition became fiercer and shaped the colonization process; this study will be helpful in understanding the colonization of periphytic algal communities.

To investigate the influence of nitrogen (N) and phosphorus (P) availability on the periphytic algal biomass and assemblage composition (by pigment analysis) in the eutrophic lake, natural littoral intact sediment cores in a subtropical eutrophic lake (Lake Taihu) were collected, and subjected to three levels of water N and P loading (N-P [mg. L−1]: 1.5, 0.075; 2.5, 0.125; 3.5, 0.175) in the tanks, eighteen artificial substances (glass slides) were fixed at three water depths (1, 17, and 33 cm above the surface sediment) for development of periphytic algae in each tank, respectively. The results showed that the biomass of periphytic algae on artificial substance was significantly enhanced with increasing N and P levels in water column and water depth (p < 0.05), while sediment-associated periphytic algae did not significantly increase with increasing N and P levels in water column. The development of sediment-associated periphytic algae changed the phosphorus form, calcium-bound phosphorus and inorganic phosphorus in the sediments decreased slightly, and the total phosphorus and organic phosphorus in the sediments increased. Our results suggest that N and P availability is conducive to the development of periphytic algae in subtropical eutrophic shallow lakes in spring. [ABSTRACT FROM AUTHOR]

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Heterotrophic microbial decomposers colonize submerged leaf litter in close spatial proximity to periphytic algae that exude labile organic carbon during photosynthesis. These exudates are conjectured to affect microbial decomposers' abundance, resulting in a stimulated (positive priming) or reduced (negative priming) leaf litter decomposition. Yet, the occurrence, direction, and intensity of priming associated with leaf material of differing recalcitrance remains poorly tested. To assess priming, we submerged leaf litter of differing recalcitrance (Alnus glutinosa [alder; less recalcitrant] and Fagus sylvatica [beech; more recalcitrant]) in microcosms and quantified bacterial, fungal, and diatom abundance as well as leaf litter decomposition over 30 days in absence and presence of light. Diatoms did not affect beech decomposition but reduced alder decomposition by 20% and alder-associated fungal abundance by 40% in the treatments including all microbial groups and light, thus showing negative priming. These results suggest that alder-associated heterotrophs acquired energy from diatom exudates rather than from leaf litter. Moreover, it is suggested that these heterotrophs have channeled energy to alternative (reproductive) pathways that may modify energy and nutrient availability for the remaining food web and result in carbon pools protected from decomposition in light-exposed stream sections. [ABSTRACT FROM AUTHOR]

This study evaluated the response of anamorphic fungi and biofilm algae to changes in physicochemical variables of water quality. Samples were taken at five sites of the Gutiérrez stream, located in the vicinity of Luján city (Buenos Aires Province, Argentina), a system affected by effluents from textile industries. The samples were taken at five sampling sites: two upstream sites and three sites downstream the effluent. Samples for the study of physicochemical variables (dissolved oxygen, temperature, pH, conductivity, nitrates, ammonium, chlorides, BOD, COD), as well as samples of algal biofilms developing on submerged substrates, and fungi developing on litter were collected from each site. In the case of the algae, fluorometric measurements were done to estimate biomass, production and photosynthetic efficiency. The relative and total abundances of the groups present were evaluated through microscopic observations. Regarding fungi, the species present in the different sites were determined and the sporulation rate and activities of three enzymes were evaluated. These indicators were useful to point out polluted areas, and in particular the biological indicators also showed recovery areas. The most important chemical variables indicating contaminated areas were ammonia, phosphates and COD concentration. The species of aquatic fungi were very indicative, particularly the abundance of species compared to the first site. Regarding algae, the highest sensitivity to contamination was detected through chlorophyll and minimum fluorescence (Fo). Other indicators such as sporulation rates, enzymatic activities and algae groups, provided complementary information to evaluate the state of the stream, and were sensitive to diffuse and point contamination. The application of chemical and biological indicators is recommended to increase the sensitivity of water quality analyses and to evaluate the effects of pollution. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hydrobiology is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The biomanipulation technique has been developed and implemented for decades, yielding favorable results in various lakes both domestically and globally. This technology uses fish to reduce algae biomass, giving a natural and environmentally friendly solution to improve water quality. The effectiveness of biomanipulation technology in large-scale artificial water canals, on the other hand, has been unclear. To address this, from 15 December 2019 to 30 April 2020, an in situ experimental study on the biomanipulation of periphytic algae was conducted in the Lushan section of the main canal of the Middle Route of the South-to-North Water Diversion Project (MSNWDP). The study aimed to verify the control effect of fish on periphytic algae. Various combinations of Megalobrama terminalis and Xenocypris davidi were fixed on the canal with a triangular cylindrical cage, and their feeding effects on periphytic algae were observed. The results showed that the density of periphytic algae at the bottom of the cages was substantially lower than before the experiment, with a 68.75% average reduction. We graded the food-filling results based on the amount of digestive tract content, which was represented using Arabic numerals ranging from 0 to 5. The study discovered that M. terminalis had the best adaptability to the environment, with full intestines primarily composed of periphytic algae and a food-filling degree between grades 4 and 5. X. davidi, on the other hand, had a food-filling degree of 0. Furthermore, the weight of each M. terminalis increased significantly following the experiment, whereas the weight of each X. davidi decreased to varying degrees. Additionally, the study highlights the importance of selecting the appropriate fish species for biomanipulation, as different species may have varying levels of effectiveness in controlling periphytic algae. Overall, this study provides valuable insights into the potential of biomanipulation technology in large-scale artificial water canals and other water conservancy projects. [ABSTRACT FROM AUTHOR]

Outbreaks of periphytic algae, including filamentous algae, have been observed after submerged macrophyte restoration and are common in early stages. Dynamic changes in the periphytic algae community on Vallisneria natans and artificial V. natans were investigated in situ, and their characteristics were compared on the two substrates. The results showed that more periphytic algae species occurred on V. natans (77 taxa) than on artificial V. natans (66 taxa) (F = 2.089, p = 0.047). The cell density and chlorophyll a (Chl. a) content of periphytic algae were 3.42–202.62-fold and 2.07–15.50-fold higher on the artificial substrate than on V. natans, respectively. Except for Lyngbya perelagans (i.e., the only common dominant periphytic algae species on the two substrates), the dominant species on V. natans were Cocconeis placentula and Ulothrix tenerrima, while those on the artificial substrate were Stigeoclonium aestrivale, Oscillatoria tenuis and Achnanthes minutissima. The cell density of periphytic algae was significantly affected by the total phosphorus (TP) and NO3−-N and electric conductivity on V. natans, and by TP and NH4+-N on artificial V. natans. The malondialdehyde content of V. natans was significantly correlated with the periphytic algae biomass. V. natans was more affected by periphytic algae during its slow-growing period, and the contribution order of stress to V. natans was diatoms > cyanobacteria > green algae. Our findings might contribute to the understanding the effect of substrate specificity on periphytic algae communities, and have important implications for the restoration of submerged plants in eutrophic lakes. [ABSTRACT FROM AUTHOR]

Knowing about the ecological aspects involved in the commercial breeding of aquatic organisms becomes an important tool to make aquaculture more productive and less impactful. Thus, periphyton taxon composition and biomass on different substrates and the influence of these on water quality and growth parameters of Nile tilapia fingerlings were examined. An experiment with three treatments (substrates for growth of periphyton: geomembrane, polyethylene terephthalate (PET), and bamboo) and a control (without substrate), each with five replicates, was conducted in a greenhouse with controlled aeration and temperature. Each mesocosm was populated with ten tilapia fingerlings with an average weight of 2.3 g for 30 days. Water quality parameters were not significantly different among treatments but remained within that established by the environmental legislation. In all treatments, 36 periphyton taxa were observed. The bamboo substrate was the most diverse, which could be attributed to the fact it was a natural substrate. Regarding fish growth, there was a significant difference among the treatments, with the PET treatment having a higher condition factor (kn). The bamboo substrate was good for colonization concerning alga diversity; however, fish in the PET treatment and control exhibited higher performance and algae consumption values, respectively.

Understanding of the trait-based ecology of the periphytic algal community has increased in the last decade. However, the relationship between their functional diversity and ecosystem functions, such as primary production, has been speculated on, but yet not proven. Human impacts promote changes in biotic communities leading to a risk of extinction, with consequences for the functioning of aquatic ecosystems. In this study, we unraveled the associations between the taxonomic and functional components of periphytic algal diversity, stream eutrophication, and productivity patterns. Furthermore, we simulated future patterns of species extinction to predict how productivity may change when facing extinction. Primary production and taxonomic and functional diversity of the periphytic algal communities were estimated in five streams across a trophic gradient in the Ave River basin (northwest Portugal). Our results demonstrated that eutrophication led to a unimodal pattern of taxonomic diversity, while functional diversity tended to increase with increasing eutrophication. We found that only functional diversity had a positive association with primary production. The extinction estimations indicated that almost all species found in our study were at high extinction risk. When we spatially scaled our extinction simulations, we found poor-productive streams after the extirpation of a few species. However, at the regional scale, the ecosystem supports the extinction of at least 40% of species before turning into a poor-productive system. Intermediate levels of disturbance are probably beneficial for the diversity of periphytic algal communities, to a certain extent. Moreover, functionally diverse communities were more productive, and the alleged future extinction of species is likely to lead to poor-productive streams if regionally focused conservation initiatives are not implemented. We recommend that, using simulations of functional extinction, it is possible to infer how the loss of these microorganisms could alter ecosystem functioning, to better predict human impacts on aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Periphyton in aquatic ecosystems play a crucial ecological role in element cycling and are susceptible to natural disturbances and anthropogenic activities. To understand the responses of periphytic communities to water quality factors and altitude gradients, DNA metabarcoding was employed to investigate the distribution characteristics of epilithic periphyton (comprising prokaryotes and eukaryotes).Epilithic periphyton and water were sampled at 26 sampling sites with an altitude ranging from 445 to 1,565 m in the Jue River and its three tributaries in Qinling Mountain, China. The altitudinal patterns of water quality variables were initially investigated, followed by redundancy analysis and distance‐based linear models to explore the responses of community structure to altitudes and water quality. Meanwhile, the relationship between these variables and fluorescence parameters to reflect the photosynthesis of epilithic periphyton along an altitudinal gradient was examined.The results indicated that with decreasing elevation, water quality variables including total dissolved solids (TDS), water temperature, conductivity, salinity, and concentrations of NO3−‐N, total nitrogen, and NO2−‐N increased. This pattern was closely associated with the intensification of anthropogenic disturbance downstream. Specifically, higher salinity and water temperature downstream may reduce the prokaryotic biodiversity but promote the diversity and evenness of eukaryotes; higher concentrations of total nitrogen may increase the diversity, richness, and evenness of the whole periphyton community. Furthermore, salinity, nutrients, and TDS were identified as crucial variables shaping periphyton community structure, especially salinity and TDS, which were linked to the growth of chlorophytes.The attenuated maximum photochemical efficiency of periphyton at high altitudes indicated that photosystem II was inhibited, while the enhancement of maximum photochemical efficiency at low altitudes may be attributed to the reduced abundance of synurophyceae and increased chlorophyte abundance with strong photosynthetic capacity.The spatial distribution of the structure and photosynthetic activity of the periphyton community along the altitudinal gradient of the Jue River and its tributaries showed that most water quality variables were negatively correlated with altitude. The photosynthetic efficiency of periphyton declined at high altitudes because the abundance of chlorophytes was lower at higher altitude reaches. This pattern of periphyton structural composition and function with altitude may also exist in other alpine rivers influenced by anthropogenic impacts. [ABSTRACT FROM AUTHOR]

Periphytic algae is frequently utilized as a health indicator for ecosystems. Many research studies have been conducted in China on the periphytic algae community, but none has compared the periphytic algae community structure at inflow rivers among different lakes in the Yangtze river basin. The periphytic algae were investigated at 94 sites in inflow rivers of Dianchi Lake, Danjiangkou Reservoir, Dongtinghu Lake, Poyanghu Lake, Chaohu Lake, and Taihu Lake. Based on microscopic research, eight phyla and 126 genera of periphytic algae were found in the inflow river of six lakes, with Cyanobacteria and Bacillariophyta dominating. The CCA (Canonical Correspondence Analysis) was used to analyze the association between the periphytic algae community and environmental factors in the inflow river of six lakes, and the LefSe (Linear discriminant analysis effect size) analysis was used to find enriched species in the inflow river of six lakes. We discovered that TN (total nitrogen) and TP (total phosphorus) were the driving environment variables at the basin scale based on the combined results of the CCA and the Mantel Test. The TITAN (Threshold Indicator Taxa Analysis) analysis also revealed the indicator species and their TN and TP concentration thresholds. Finally, we assessed the ecosystem health of the inflow river at six lakes; biotic and abiotic indices yielded conflicting results, but utilizing both indices to assess ecosystem health using the Random Forest algorithm will yield objective and comprehensive results. [ABSTRACT FROM AUTHOR]

In order to explore the characteristics of the periphytic algae community structure and its relationship with environmental factors in the Taiyuan region of the Fenhe River, a total of six sampling sites were investigated in July and December 2021. The effects of water quality status and environmental factors at each sampling point on the community structure of epiphytes were detected. The results showed that a total of 7 phyla and 54 genera of periphytic algae were identified in the Taiyuan region of the Fenhe River, and the species composition was mainly Bacillariophyta, Cyanophyta, and Chlorophyta. According to the analysis results of the biodiversity index, the water body of the Taiyuan region of the Fenhe River is in a state of moderate pollution. The correlation analysis between the epiphytic algae and environmental factors showed that the cell density of algae was significantly correlated with dissolved oxygen (DO), phosphate ( PO 4 3 − -P), chemical oxygen demand (COD), total phosphorus (TP), and transparency (SD) in the wet season. The algal cell density in the dry season was significantly correlated with water temperature (WT), TP, PO 4 3 − -P, and COD. According to the redundancy analysis, the community distribution of the epiphytic algae in the Taiyuan region of the Fenhe River was closely related to physical and chemical factors such as COD, nitrate nitrogen ( NO − 3   -N), WT, dissolved organic carbon (DOC), total nitrogen (TN), and TP, and COD is the main environmental factor driving the change in the community distribution of the periphytic algae in the wet season. TN is the main control factor driving the change in the biological community distribution of periphytic algae in the dry season. [ABSTRACT FROM AUTHOR]

Nile tilapia is a highly invasive fish species, deliberately introduced into many lakes and reservoirs worldwide, sometimes resulting in significant ecosystem alterations. A short-term mesocosm experiment with and without Nile tilapia (Oreochromis niloticus) was designed to test the hypotheses that the presence of tilapia may affect phytoplankton community structure, increase nutrients availability in water column and deteriorate water quality. Nutrients, total suspended solids (TSS) and biomass of phytoplankton in different size classes (as Chl a) were measured. We found that tilapia increased the total nitrogen (TN), total dissolved nitrogen (TDN), NH4+ and TSS concentrations, deteriorating the water quality. In addition, under tilapia presence, the biomass of phytoplankton, as well as that of micro- and nano-phytoplankton, increased leading to a change in the structure of the phytoplankton assemblage. Moreover, a reduction in the biomass of periphyton was observed. Omnivorous tilapia is often dominant in tropical and subtropical waters, and removal of this fish may represent an effective management tool to improve the water quality. [ABSTRACT FROM AUTHOR]

Periphytic algae is a useful indicator of aquatic ecological conditions. We investigated the periphytic algae on natural substrate and the environmental variables at 44 sites on three river systems in the Weihe River Basin (WRB). A total of 84 species are identified, representing 37 genera. The most common genera were Navicula, Oscillatoria, Nitzschia, Scenedesmus, Cymbell, and Fragilaria. One-way analysis of variance (ANOVA) indicated significant differences among the three river systems in environmental variables (p < 0.05). Non-metric multidimensional scaling (NMDS) analyses also showed differences in periphytic algae communities in the three river systems (p < 0.05) and identified different dominant species in each river system. Canonical correspondence analysis (CCA) and Monte Carlo permutation tests revealed that nutrient concentration, WT, and altitude were the most important variables affecting the structure and distribution of periphytic algae communities. Chemical variables were the most accounted for environmental variables (12.5%), while physical variable and geographical factors (5.8% in total) play a relevant minor role. Our results demonstrate that Navicula pupula, Navicula radiosq, Nitzschia palea, and Nitzschia denticula, exhibiting wide ecological amplitude, are tolerant of high concentrations of nutrient pollution. Variation of periphytic algae communities in WRB is due to the combination of anthropogenic and natural factors including agricultural and domestic wastes water inputting, land use patterns, geology, climatic changes, and river hydrology. HIGHLIGHTS Structure and distribution of periphytic algae communities were investigated in the Weihe River Basin.; The gradient of organic pollution detected in environmental variables was the main gradient, and the periphytic algae responded to this gradient.; The types of substrates in river impact periphytic algae abundance, causing higher periphytic algae abundance in cobbles substrate.; The variation of periphytic algae communities is attributed to the combination of anthropogenic factors and natural factors.; The results support the periphytic algae as ecological indicators in the Weihe River Basin.;

Copyright of Journal of Hydrobiology is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The macrophyte–algae relationship has primary importance in affecting the functioning of shallow lake ecosystems. However, how substratum type, grazing, and nutrient status affect the relationship, is still largely unknown. Here, we studied algal assemblages covering either the submerged macrophyte, Ceratophyllum demersum, or artificial plastic plants with similar morphological complexity to answer these questions. Nutrient status was assessed as eu- and hypertrophic conditions in two separate lakes. In contrast to previous studies, the algal community on artificial substrates resembled to those observed on C. demersum. Independently of nutrient status (lakes), algae colonised artificial substrates intensively, but the highest algal biomass was observed in the hypertrophic lake. The community of periphytic algae was represented by diatoms, chlorophytes, and cyanobacteria. In the eutrophic lake, rather diatoms were present with high relative abundance, whereas, in the hypertrophic lake, rather cyanobacteria prevailed. Grazing pressure was high in both lakes and in the case of both substrate types, affecting the biomass of periphytic algae significantly. Our results indicate that macroinvertebrate grazing plays a crucial role in affecting periphytic algal biomass, independently of nutrient status and substratum type in shallow lakes.

Introduction: Research and diagnosis of water sources is of academic and governmental interest, for this reason, the exploration of numerical tools applied to watershed management, offers the possibility to identify where and what variables are useful in monitoring and rehabilitation programs of aquatic ecosystems. Environmental planning and management, which includes water quality, is conventionally analyzed by physical, chemical and hydrobiological indexes. In 2014, through the water management guide, included the assessment of the ecological quality index (EQI); it was generated a comprehensive approach through a numerical system of correlations that diagnoses, classifies and detects environmental impacts. Objective: This research aims to demonstrate that the EQI allows to assess the quality of aquatic ecosystems affected by different environmental situations. Methods: In order to analyze the application of this tool, we studied three scenarios located in different biogeographical regions of Colombia and, as a hydrobiological group indicator, we used peripheral and phytoplankton algae. The ecosystems were monitored between 2007 and 2015 and correspond to a flood plain, a high mountain Andean river and a group of water stream in a tropical humid forest. Results: Canonical correlations were significant (P < 0.005) and a model of weighted averages, allowed to estimate the optimum and the tolerance of each taxa for the sites ecological classification; variables related to ion concentration, acidity damping, temperature and hydraulics, influenced the models that explained the abundances distribution of the studied biological groups. Conclusions: The application of the EQI makes it possible to identify variables, organisms and numerical systems to classify ecological status. These results are useful in the diagnosis and monitoring of aquatic ecosystems and that can be implemented in other scenarios. [ABSTRACT FROM AUTHOR]

The macrophyte-algae relationship has primary importance in affecting the functioning of shallow lake ecosystems. However, how substratum type, grazing, and nutrient status affect the relationship, is still largely unknown. Here, we studied algal assemblages covering either the submerged macrophyte, Ceratophyllum demersum, or artificial plastic plants with similar morphological complexity to answer these questions. Nutrient status was assessed as eu- and hypertrophic conditions in two separate lakes. In contrast to previous studies, the algal community on artificial substrates resembled to those observed on C. demersum. Independently of nutrient status (lakes), algae colonised artificial substrates intensively, but the highest algal biomass was observed in the hypertrophic lake. The community of periphytic algae was represented by diatoms, chlorophytes, and cyanobacteria. In the eutrophic lake, rather diatoms were present with high relative abundance, whereas, in the hypertrophic lake, rather cyanobacteria prevailed. Grazing pressure was high in both lakes and in the case of both substrate types, affecting the biomass of periphytic algae significantly. Our results indicate that macroinvertebrate grazing plays a crucial role in affecting periphytic algal biomass, independently of nutrient status and substratum type in shallow lakes. [ABSTRACT FROM AUTHOR]

Abstract Aim: The aim of this study was to assess the taxonomic aspects and geographical distribution of the periphytic desmids from two different substrates in the littoral zone of an urban artificial lake. Methods Samples of epiphytic and epilithic desmids were collected by grass and rock scraping, respectively, in two stations in the Cascavel municipal lake, Paraná, during April 2015, and March 2016 and 2017. In the laboratory, the taxa obtained from the samples were photographed and their morphometric characteristics recorded. The species composition of the desmid was characterized, and the frequency of occurrence as well as the geographic distribution of each taxon in the Paraná State were recorded. Results We identified 35 taxa, distributed in 10 genera. The most representative were Closterium Nitzsch ex Ralfs and Cosmarium Corda ex Ralfs. A high occurrence of sporadic taxa (60%) was observed and among the recorded taxa, the most frequent were Cosmarium pseudoconnatum Nordstedt var. pseudoconnatum and Desmidium grevillei (Kützing ex Ralfs) De Bary. Nine taxa were exclusive to the epilithic substrate and only Netrium digitus (Ralfs) Itzigsohn & Rothe var. digitus was exclusive to the epiphytic substrate, while the remaining 25 taxa occurred in both substrates. Seven taxa are new records for the Paraná State. Conclusion Although our results are of qualitative nature, they provide baseline data on the biogeographic distribution of taxa, which are crucial for future taxonomic and ecological studies that might contribute to the preservation of the biodiversity.

Habitat complexity plays a significant role in biological communities, but its effect on periphyton is still poorly understood. For example, the response of periphyton to changes in habitat relative to colonization time remains to be elucidated. Our hypothesis was that habitat complexity positively affects periphyton biomass, algal diversity, and change in species composition, while the response of periphyton to habitat complexity depends on colonization time. To test this hypothesis, we evaluated periphyton on artificial substrate distinct levels of habitat complexity at the intermediate (15 days) and advanced phases of colonization (30 days). Biomass, species richness, and diversity increased with level of structural complexity, but these attributes present significant difference only at the 15th day of colonization. In contrast, species composition changed with the increase of fractal dimension at both colonization times. Algal community response to distinct levels of structural habitat complexity was most significant at the 15th day of colonization. Our results showed that biomass, adaptive strategies groups, and taxonomic structure in periphyton were affected by habitat complexity, but that response was dependent on colonization time. Therefore, we concluded that colonization time is a factor that should be considered in assessing the effects of habitat complexity on periphyton. [ABSTRACT FROM AUTHOR]

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O estudo visou avaliar, em um experimento de mesocosmos, a influência da temperatura e de concentrações de nutrientes na abundância das algas perifíticas (exceto Bacillariophyceae) na planície de inundação do alto rio Paraná. O delineamento experimental constituiu-se de cinco tratamentos: controle (C) e adição de nutrientes (P+, N+ e NP+) a 25ºC, e frio (F) com diminuição da temperatura a 15ºC e sem adiçãode nutrientes. Lâminas de vidro foram utilizadas para colonização das algas perifíticas, e as amostragens foram feitas entre o 15º e o 31º dia de sucessão. Pela Análise de Correspondência Canônica, pode-se observar uma clara separação entre os tratamentos devido à temperatura e adição de nutrientes. A diminuição de temperatura afetou a abundância das classes de algas perifíticas, principalmente pela redução da densidade relativa de Cyanophyceae e aumento de Zygnemaphyceae. O enriquecimento artificial de nutrientes, principalmente P, alterou a estrutura da comunidade de algas perifíticas, em termos de densidade das classes algais. As densidades relativas das classes, em geral, aumentaram com a adição de nutrientes. O fósforo pode ser considerado direcionador na densidade das algas perifíticas, como pode ser observado pela rápida resposta após os enriquecimentos artificiais.This study set out to evaluate, via a mesocosm experiment, theinfluence of the temperature and concentration of nutrients (N and P) in the abundance of periphytic algae (except Bacillariophyceae) of the upper Paraná river floodplain. The experiment was designed using 5 treatments: a control (C), added nutrients (P+, N+, NP+) at 25ºC, and without added nutrients at 15ºC. Glass slides were used for periphytic algae colonization, and the samples were taken on the 15th and 31st days following colonization. Canonical Correspondence Analysis revealed a clear separation among treatment groups due to temperature and added nutrients. A decrease in temperature affected the abundance of periphytic algae classes, especially in the reduction of the relative density of Cyanophyceae and increase in Zygnemaphyceae. The artificial addition of nutrients – especially P – altered the structure of the periphytic algae communities. Therelative densities of the classes, in general, increased with the addition of nutrients. Phosphorus may be considered a driver of periphytic algae, as can be seen by the rapid response after artificial enrichment.

Este trabalho objetivou analisar a riqueza e a abundância de algas perifíticas nos rios do Corvo e Guairacá, tributários do reservatório de Rosana, quando da instalação de tanques-rede. Acreditava-se que o ponto logo à frente dos tanques-rede apresentaria menor riqueza e abundância de algas e que o reservatório influenciaria as estações a jusante dos tanques. Para isso, coletas foram realizadas a montante, em frente e a jusante da instalação de tanques-rede. Independentemente do ambiente, a estação que apresentou maior riquezafoi 1.000 m a montante. Diminuição na riqueza foi verificada nas estações 500 m a montante e 500 m a jusante. Quanto à densidade, em frente aos tanques, observou-se maior abundância, seguida pela estação a 1.000 m a jusante. Já, nas estações de amostragem a 500m (a montante e jusante), o número de indivíduos foi inferior às demais. Assim, independentemente do ambiente lótico, constatou-se menor riqueza e abundância de algas perifíticas nas estações a 500 m dos tanques, o que reforça a importância de ser realizado obiomonitoramento em uma área de maior abrangência.This study aimed to analyze the richness and abundance of periphytic algae in Corvo and Guairacá rivers, both tributaries of the Rosana reservoir. It was believed that the site just ahead of the installation of net cages presented less richness and abundance of algae. For this, samples were collected 500 and 1,000 m upstream, and downstream and in front of the net cage. Regardless the environment influence, the station that recorded the highest number of species was the 1,000 m upstream. And those that recorded the lowest richness were 500 m upstream and downstream. In front of the tanks was the most abundant, followed by the 1,000 m downstream. On the other hand, the abundance on the 500 m stations was the lowest. Thus, regardless of the lotic environment, less richness and abundance of periphytic algae was found in stations 500 m from the cages, which reinforces the importance of carrying out biomonitoring in an area of greater coverage.

A pesquisa objetivou avaliar a variação espacial e temporal da comunidade de algas perifíticas em dois ambientes do baixo rio Doce: lagoa Juparanã e rio Pequeno. Foram realizadas coletas trimestrais (agosto/04 a maio/05) em duas estações amostrais, uma na lagoae outra no rio. Foram coletados pecíolos de Eichhornia azurea (Sw.) Kunth. Os atributos da comunidade analisados foram: riqueza de táxons, freqüência de ocorrência, densidade, abundância e dominância. Na lagoa Juparanã, foram registrados 86 táxons e a densidadevariou de 20.592 ind cm-2 (mai/05) a 88.712 ind. cm-2 (nov/04). No rio Pequeno, foram registrados 83 táxons e a densidade variou de 16.049 ind. cm-2 (fev/05) a 71.663 ind. cm-2 (ago/04). Em ambos os ambientes, as classes predominantes qualitativamente foramCyanophyceae, Bacillariophyceae e Zygnemaphyceae, havendo domínio das formas filamentosas e unicelulares seguidas das coloniais. As classes Cyanophyceae e Bacillariophyceae foram mais representativas quantitativamente. Não houve variação espacial. Pluviosidade, temperatura da água, condutividade elétrica e transparência foram asvariáveis que mais oscilaram conforme a estação (seca ou chuvosa) e as que apresentaram maior número de correlações significativas com as variáveis biológicas, evidenciando heterogeneidade temporal.This research aimed to evaluate the spatial and temporal variation of the periphytic algae community within two environments of the lower Doce River: Juparanã Lagoon and Pequeno River. Samplings were carried out every three months from August 2004 to May 2005 at both sites. Natural substrata of Eichhornia azurea (Sw.) Kunth petioles were collected from the sites. The community was analyzed according to species richness, frequency of occurrence, density of organisms, abundance and dominancy. Eighty-six taxa were recorded in the lagoon,and the density of organisms varied from 20,595 ind. cm-2 (May/05) to 88,712 ind. cm-2 (Nov/04). Eighty-three taxa were recorded in the river, and the density of organisms varied from 16,049 ind cm-2 (Feb/05) to 71,663 ind. cm-2 (Aug/04). At both sites, the classes thatpredominated qualitatively were Cyanophyceae, Bacillariophyceae and Zygnemaphyceae, in which filamentous and unicellular forms dominated, followed by colonial forms. Quantitatively, the most representative classes were Cyanophyceae and Bacillariophyceae. A spatial variation was not observed. Precipitation, water temperature, electric conductivity and transparency were the variables that most oscillated according to seasonal variation (dry or rainy season). They alsopresented a greater number of significant correlations with the biological variables, showing evidence of temporal heterogeneity.

In order to understand the biodegradability of algal-derived organic matter, biodegradation experiments were conducted with C and N-labeled natural phytoplankton and periphytic algal populations in experimental conditions for 60 days. Qualitative changes in the dissolved organic matter were also determined using parallel factor analysis and the stable carbon isotopic composition of the hydrophobic dissolved organic matter through the experimental period. Although algal-derived organic matter is considered to be easily biodegradable, the initial amounts of total organic carbon newly produced by phytoplankton and periphytic algae remained approximately 16 and 44 % after 60 days, respectively, and about 22 and 43 % of newly produced particulate nitrogen remained. Further, the dissolved organic carbon derived from both algal populations increased significantly after 60 days. Although the dissolved organic matter gradually became refractory, the contributions of the algal-derived organic matter to the dissolved organic matter and hydrophobic dissolved organic matter increased. Our laboratory experimental results suggest that algal-derived organic matter produced by phytoplankton and periphytic algae could contribute significantly to the non-biodegradable organic matter through microbial transformations. [ABSTRACT FROM AUTHOR]

Periphytic algae are important primary producers in water bodies, which play an important role in maintaining ecological function and water purification. Previous studies have shown that plastic is a good substrate for periphytic algae, and different plastic materials have different effects on the colonization of periphytic algae; however, there are few reports on the effects of plastic color on the growth of periphytic algae. In this study, polycarbonate plastic (PC) of various colors were used as the substrate to study the effects of different colors on the growth and community structure of periphytic algae by measuring the biomass, photosynthetic activity, and community composition. The results showed that the growth of periphytic algae was inhibited by the brown PC plastic, and the contents of chlorophyll a and dry weight in this group were significantly lower than those in other groups. Green PC plastic inhibited the photosynthetic activity of periphytic algae, and the actual photosynthetic efficiency (Yield) of the group was significantly lower than that of the other groups. The influence of PC plastic with different colors on periphytic algae occurred mainly in the early colonization/development stage but was not significant in the late community maturity stage. On day seven of the experiment, the community composition of periphytic algae was significantly different between the transparent PC plastic group and the green PC plastic group. By contrast, on days 25 and 40, there were no significant differences in the community structure of periphytic algae. In the early stage of the experiment, the dominant genus was Pseudoranea (Cyanophyta), and in the middle and mature stages, the dominant genus was Mougeotia (Chlorophyta). In this study, the effects of different colors of polycarbonate plastics on periphytic algae were investigated, which provided new insights for selecting suitable substrates for water pollution treatment by using periphyton biotechnology.

The epiphytic algae community and the environmental factors of Jinyang Lake were monitored from March 2010 to February 2011. Cluster and Non-matric Multi-Dimentional Scaling (MDS) methods were used respectively to do multivariate statistical analysis of the seasonal changes of community structure of periphytic algae. The periphytic algae communities of all the plots from different seasons were clusterred into several groups based on the different community structure. The contribution of five main factors, water temperature, air temperature, dissolved oxygen, pH and conductivity, on the distribution pattern were analyzed by Principal Component Analysis (PCA) method and the results showed that, the water temperature was the most effective in all four seasons. Taken together, the water quality in Jinyang Lake was still acceptable. However, more attention should be paid on proper development and usage of the touring and fishing resources. [ABSTRACT FROM AUTHOR]

The Salton Sea in the Imperial Valley of California is a threatened ecosystem. To address the challenges related to trace element accumulation and eutrophication, a 270 m long attached periphytic algae flow-way was deployed at the Alamo River Wetlands, a tributary of the Salton Sea. To assess opportunities for efficient generation of biomass from reclamation of run-off-derived nutrients, the quantities of available and biosorpbed nutrients, organics, and trace elements were monitored. Over the course of 2 years, persistent algal biomass production was achieved at an average ash-free biomass productivity of 5.8 ± 2.7 g/m2/day for the full flow-way length. Overall, harvested biomass consisted of high ash (76.3 ± 5.4%) and low lipid (1.1 ± 1.0%) content, which are typical of periphytic algal biomass. Nitrogen removal rates of 530 ± 190 mg N/m2/day, phosphorous removal rates of 14 ± 6 mg P/m2/day, and 73 ± 25% of BOD (Biological Oxygen Demand) removal rates were achieved. Furthermore, spatial variations of the biomass productivity along with nutrient removal rates were observed to have a decreasing trend over the length of the flow-way, while N and P contents of the biomass showed increasing trend, indicating variable nutrient utilization efficiency as an important factor for system scaling. Temperature and solar irradiation were found to be key environmental factors for biomass productivity and nutrient removal rates. However, stable uptake of nutrients, organics, and metals in the biomass, despite intermittent variation of the analyte concentrations in the source water, indicate the resilience of attached periphytic algae biomass production at dilute nutrient concentration regimes. Trace metal analysis of the water from the surrounding area revealed levels exceeding federal toxicity guidelines for Selenium and Copper. Significant bioaccumulation of these and other metals contaminants were also identified in the harvested biomass, including Nickel, Chromium, Cadmium and Lead. Together these findings demonstrate several potential value propositions for attached algae cultivation from agricultural runoff-impacted surface waters, including remediation of N/P nutrients, organics, and common toxic metals, concomitant with biomass production. • A 270 m algae flow-way was deployed at the Alamo River Wetlands, Brawley, CA. • Composition of the harvested algae biomass was high in ash, protein, and carbohydrates • Efficient biomass production is provided by biosorption of N/P and organics by the algae. • Trace element analysis showed uptake of Se and bioaccumulation of Ni, Cr, Cd and Pb. [ABSTRACT FROM AUTHOR]

Climate change is altering temperatures and precipitation patterns all over the world. Melting glaciers increase surface run-off, thereby increasing the transport of suspended solids through streams. The increased load of suspended solids affects turbidity, which decreases the availability of photosynthetically active radiation for primary producers., We analysed how glacial loading of clays influences the light : nutrient ratio and photosynthetic parameters (measured with a pulse amplitude modulated fluorometer) and the carbon : phosphorus ( C : P) elemental ratio of periphytic primary producers. A field study was conducted in two canopy-free streams that receive water from the glaciers of Mount Tronador ( Patagonia, Argentina), one with high glacial load and the other with clear water. In addition, we conducted an in situ colonisation experiment with three different light treatments., We observed that periphytic biomass (chlorophyll a and carbon content) in the streams and in the experiment varied directly with turbidity. Moreover, photosynthetic parameters varied similarly because of an increase in the efficiency of electron transfer per open reactive centre in the more turbid stream and a chronic photoinhibition of photosystem II in the clearer stream., Periphytic C : P also varied with turbidity as we observed a decrease in C : P with an increase in light in both streams and in the experiment., Our main conclusion is that an increase in glacial melting with its associated increase in glacial clay load should protect primary producers against high irradiances (photosynthetic active radiation + ultraviolet radiation) in canopy-free streams. [ABSTRACT FROM AUTHOR]

La Miel River is a tributary of the Magdalena basin and the main tributary of the Amaní reservoir. In order to establish the spatial and temporal dynamics of periphytic algae genera downstream of the reservoir, data collected every two months between 2006 and 2009, at seven sampling sites (five in the main channel and two tributaries) were analyzed. 130 genera and 15 classes were recorded, Cyanophyceae and Bacillariophyceae being the most representative in density and frequency. Both the generic density and richness showed significant variations in the spatial dimension, but did not differentiate the sampling sites on the La Miel River from those in tributaries and did not show a specific pattern related to hydrological seasons; but changes of richness were observed between samples and a association between the algal community and parameters related to water dynamics was found. We conclude that although the variables analyzed are not limited by the discharge, other structural characteristics of the community such as the taxonomic composition and diversity are affected, especially at the site of direct influence of this process. [ABSTRACT FROM AUTHOR]

Four submerged macrophytes were analysed with their respective assemblages of chironomid and algal taxa. Studies were made bimonthly, from January to November, in a shallow macrophyte-dominated lake. The periphytic algal community was represented by chlorophytes, diatoms and cyanobacteria; diatoms showed the highest relative abundance on the macrophyte species during the study. Algal biomass was affected by the season, and in January the highest values were found on Stratiotes aloides L. , Potamogeton lucens L., Myriophyllum spicatum L.; in July on Chara aculeolata Kütz. The lowest algal biomass, on most of the macrophytes studied, was found in September. Larvae of Dicrotendipes sp., Diplocladius cultriger Kieffer, Endochironomus albipennis gr., Endochironomus impar (Walker), Glyptotendipes sp. and Paratanytarsus austriacus Kieffer were dominant within the chironomid community. The spatial distribution of chironomids between macrophytes species was related to periphytic algae biomass and certain environmental variables (temperature, water transparency, biomass of chlorophytes and diatoms). Analysis of chironomid diet and the results of canonical correspondence analysis confirmed this relationship. The strongest chironomid-algae relationships were observed on S. aloides and P. lucens. [ABSTRACT FROM AUTHOR]

This study of periphytic algae and gastropods differentiation on macrophytes, stones, and dam substrates and the relationships between these communities in the vegetative season of 2001-2003 was conducted in the vicinity of a hydroelectric plant on the Pasłeka River. Damming the river caused decreased water discharge upstream from the plant, and increased it downstream. Thus, oxygen conditions downstream from the plant improved, but high nutrient concentrations were also recorded. Generally, increased orthophosphate concentrations do not allow river waters to be classified as having good or maximum ecological potential. Damming contributed to changes in the growth conditions of the periphytic algae and gastropods and their differentiation. The highest biomass of periphytic algae was noted on the dam, while the highest gastropods biomass was noted on macrophytes. The periphytic algae was dominated by the diatoms Diatoma vulgaris and Melosira varians (epiphyton, dam) and the chlorophytes Ulothrix tenuissima and Spirogyra sp. (epilithon), while the gastropods were dominated by Lymnea stagnalis (macrophytes), Theodoxus fluviatilis (stones), and Radix balthica (dam). The relationship between the gastropods and the periphytic algae on macrophytes and the dam in spring and summer revealed an increase in gastropods biomass and a decrease in periphytic algae biomass. This was indicated by the negative correlation between the biomass of these communities. [ABSTRACT FROM AUTHOR]

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Temperature is a strong driver of biofilm formation and of the dynamics of microalgae in freshwater. Moreover, exposure to herbicides is a well-known stressor of periphytic communities in anthropized aquatic environments. We tested these two environmental factors on periphytic communities that had been sampled from the littoral zone of Lake Geneva and acclimatized in the lab for 3 weeks at 18, 21, 24 and 28°C. After this acclimation period, differences in the composition of the diatom community and decreases in cell density were observed corresponding to the temperature gradient. These acclimated communities were then exposed to 23 and 140nM of a mixture composed of equitoxic quantities of atrazine, terbutryn, diuron and isoproturon. The periphytic community was more sensitive to the herbicide mixture at 18°C than at higher temperatures, suggesting that higher temperature reduced its toxicity. Small and pioneer diatom species known to be promoted by contamination also appeared to benefit from higher temperatures. Temperature therefore appears to condition the herbicide sensitivity of periphytic communities. [Copyright &y& Elsevier]

The macrophyte-periphyton complex has great importance for the functioning of shallow lakes and reservoirs. Several observations in the field have suggested that macrophyte life-form and architecture seem to be very important for periphytic algal community organization. To test the influence of macrophytes on periphyton, we compared the algal community structure and nutrient status (C, N, P) of periphyton on the stem and leaves of Utricularia foliosa L., and on a nylon thread utilized as an artificial substrate. Furthermore, this study aims to assess the seasonal variation of limnological conditions and their influence on Utricularia-periphyton complex. Spring and summer had higher light conditions, P availability and macrophyte cover than autumn and winter. Algal biomass, total density, and biovolume were higher on natural substrate than on artificial. Algal assemblages changed with season and species descriptors differed among substrates types. Phosphorus content of periphyton was generally more correlated with water nutrient availability than with N and C content. Periphyton on free-floating submersed macrophytes may have great importance on the functioning of shallow tropical reservoirs, particularly in the clear water state. Moreover, seasonal variation of limnological conditions determines the periphyton- Utricularia relationships and either intensifies or minimizes the macrophyte influence on periphyton. [ABSTRACT FROM AUTHOR]