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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]

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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]

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]

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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]

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]

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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 inWRB 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. [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]

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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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]

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]

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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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]

Seasonal primary productivities of periphyton and phytoplankton were compared in Grande Lake (GL) and a relict oxbow lake (ROL) in winter 2006 and summer 2007. GL was free of floating plants on the sampling dates and covered over 80 and 100% of the ROL surface in winter and summer, respectively. The C assimilation technique was used to obtain the P- E curves of phytoplankton and periphyton on artificial substrata. The periphytic maximum photosynthetic rate ( P) was higher in the ROL in winter and summer, being better adapted to low irradiances than those in the GL. Phytoplankton and periphytic algae were light-limited in the ROL in summer due to complete coverage by floating macrophytes. In summer, P and α values for periphyton in the ROL were higher than those for phytoplankton, and were even higher than in GL. In turn, P and α values for phytoplankton in Grande Lake were higher than those for periphyton due to improved light conditions and the presence of algae that were adapted to movement through the water column. These results suggest that the complete coverage by floating macrophytes restricted phytoplankton productivity and allowed the development of a periphytic community that was better adapted to low-light conditions. [ABSTRACT FROM AUTHOR]

The objectives of this study were to evaluate the effect of cyanobacterial blooms on periphyton algal succession and to identify the factors determining community dynamics in a tropical hypereutrophic reservoir. A variety of factors affecting periphytic community structure were identified at two different sites with domestic sewage and spring water inflows and two climatic periods. Microscope glass slides were used to assess periphyton growth. Sampling was carried out at short regular intervals (3-5 days) over 30 days. Climatic periods were limnologically distinct. The rainy period was characterized by an intense cyanobacterial bloom and the dry period by a less intense bloom. Periphyton biomass and growth tended to increase with colonization time during the dry period. Cyanobacteria and Bacillariophyceae were the most representative groups in the rainy period whereas Bacillariophyceae was dominant in the dry period. Community species had successional patterns in both climatic periods. The successional trajectory for sites 1 (domestic sewage) and 2 (spring water) was different in the dry period but similar in the rainy period. We concluded that the community structure over 30 days of colonization under hypereutrophic conditions was primarily determined by seasonal scale ( bloom intensity), followed by successional scale ( autogenic), and, finally, by the local scale ( spring water and sewage inflow). Positive periphyton biological response (higher biomass and algal growth, dominance of diatoms, Cyanobacteria reduction) during small variations of bloom intensity may indicate rapid re-establishment of the community during recovery of the ecosystem. [ABSTRACT FROM AUTHOR]

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Copyright of Acta Scientiarum: Biological Sciences is the property of Universidade Estadual de Maringa 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.)

Copyright of Acta Scientiarum: Biological Sciences is the property of Universidade Estadual de Maringa 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 ratio of the amount of treated wastewater to river water is increasing in urban areas due to the spread of sewage systems. Treated wastewater is also sometimes extensively used to create streams and other water environments in urban areas. Rivers, streams and other water environments provide valuable habitats for all kinds of aquatic species, but the relationship between such aquatic species and the quality of treated wastewater they inhabit is not clearly understood. This study was carried out to clarify the effect of the water quality of treated wastewater such as nutrients and residual chlorine on periphytic algae grown in a stream receiving treated wastewater using laboratory-scale experimental channels. The following results were obtained. (1) When the range of phosphate (PO4-P) concentration was 0. 04 to 0. 09 mg/L, the higher the PO4-P concentration, the higher the biomass of periphytic algae and the more dominant the Chlorophyceae. (2) When the range of total residual chlorine (TRC) concentration was 0. 07 to 5. 8 mg/L, the higher the TRC concentration, the lower the biomass of periphytic algae. When the range of TRC concentration was 0. 93 to 5. 8 mg/L, this tendency was more pronounced. [ABSTRACT FROM AUTHOR]