Periphyton Communities Research Articles

Disentangling effects of droughts and heatwaves on alpine periphyton communities: A mesocosm experiment

AbstractThe accelerating rate of global climate change at higher elevations and latitudes is increasing the potential for extreme climatic events. Here, a knowledge gap exists in how the order of exposure to, and duration of droughts and heatwaves affect their cumulative impact on aquatic communities. We tested experimentally for the legacy effects of simultaneous vs. sequential exposures to drought and heatwave on sediment‐dwelling algal communities (epipelon) from small fishless alpine lakes. In both simultaneous, and sequential exposure treatments involving drought followed by a heatwave, the negative effect of drought masked the effects of warming on chlorophyll‐inferred algal biomass and taxonomic composition. Reversal of order of exposure (i.e., heatwave followed by drought) lowered their cumulative effect on community structure. These findings highlight the potential for drought events to dominate over heatwaves in altering shallow littoral ecosystems at high elevations under a rapidly warming climate.

Comparison of periphyton growth on two artificial substrates in temperate zone fishponds

Periphyton communities are fundamental components of freshwater ecosystems that influence water quality, nutrient cycling, and productivity. Additionally, periphyton communities serve as valuable food sources in aquaculture. The periphyton communities on two substrates—heather mats and geotextiles—were compared in four temperate fishponds. After 51 days of immersion, the geotextiles exhibited significantly greater fluorescence, indicating a greater abundance of algae and cyanobacteria. Conversely, the abundance (and biomass) of periphyton invertebrates on heather mats was greater than that on geotextiles, and the difference became more pronounced over time. These differences resulted from significantly greater dipteran larval abundances (biomasses) on the heather mats than on the geotextiles. This study suggested that heather mats can significantly enhance food abundance and availability within the water column under Central European conditions.

Does exposure timing of macrolide antibiotics affect the development of river periphyton? Insights into the structure and function

Discharged sewage is the dominant source of urban river pollution. Macrolide antibiotics have emerged as prominent contaminants, which are frequently detected in sewage and rivers and pose a threat to aquatic microbial community. As a typical primary producer, periphyton is crucial for maintaining the biodiversity and functions of aquatic ecosystem. However, effects of antibiotic exposure time as well as the recovery process of periphyton remain undetermined. In the present study, five exposure scenarios of two typical macrolides, erythromycin (ERY) and roxithromycin (ROX) were investigated at 50 µg/L, dose to evaluate their potential detrimental effects on the structure and function of periphyton and the subsequent recovery process in 14 days. Results revealed that the composition of periphytic community returned to normal over the recovery period, except for a few sensitive species. The antibiotics-caused significant photodamage to photosystem II, leading to continuous inhibition of the photosynthetic capacity of periphyton. Furthermore, no significant difference in carbon metabolism capacity was observed after direct antibiotic exposure, while the amine carbon utilization capacity of periphyton remarkably increased during the recovery process. These results indicated that periphyton community was capable of coping with the periodic exposure of antibiotic pollutants and recovering on its own. However, the ecological functions of periphyton can be permanently disturbed due to macrolide exposure. Overall, this study sheds light on the influence of macrolide exposure on the development, structure and function of the periphytic microbial community in rivers.

Environmental gradients and anthropogenic landscape modification determine composition of functional traits of periphyton community in Brazilian Cerrado streams

Environmental gradients and anthropogenic landscape modification determine composition of functional traits of periphyton community in Brazilian Cerrado streams

Beyond biomass: Resource effects on primary production and consumer nutrient assimilation in streams

Abstract Primary production in aquatic ecosystems is strongly controlled by resource availability (bottom‐up). At the same time, grazers exert top‐down pressure on algae. The effects of both resources and grazers on algal communities have been investigated extensively for both benthic and planktonic systems. However, most studies focus exclusively on net effects on algal standing stock, while the underlying ecological functions and processes often remain unknown. Here, we tested the effects of the two resources, light (L) and the limiting nutrient phosphorus (P), on both primary production (net oxygen production) by benthic algae (periphyton) and matter assimilation by the next trophic guild (particularly nitrogen assimilation by grazers). For this, we grew natural periphyton communities in stream mesocosm flumes together with two native grazer taxa and 15N as a tracer. Both resources resulted in an initial increase in net primary production, but this effect equalised after 36 days in the more mature communities. While both resources still showed strong positive effects on algal biovolume, the biovolume‐specific net primary production decreased with resource level and was lowest in the double elevated (+L, +P) treatment. The response of nitrogen assimilation by grazers was more closely related to the response of periphyton quality (stoichiometric and taxonomic composition) than to its biomass. In addition, light affected the nitrogen assimilation of both grazers negatively. These findings demonstrate that the responses of ecological functions, here primary production and assimilation by grazers, are not necessarily proportional to algal biomass and are thus not easily predictable from the common use of biomass as a proxy for functions.

Longitudinal effects of land-cover transitions on the periphyton community of a tropical stream

Our study aims to investigate the longitudinal effects of two land-cover transitions on the periphytic algal community. We utilized datasets from three different studies conducted over a 5-year interval in a tropical headwater stream. The studied stream traverses two abrupt adjacent transitions from an upstream forest to a pasture and back to a downstream forest remnant. We performed a high-spatial resolution sampling and used generalized additive models (GAMs) to capture the non-linear gradient response of algal metrics to distance from land-cover transitions. Algal biomass presented a lagged response to increased light availability along the pasture section and decreased along a shorter distance in the downstream forest. Most algal metrics presented a lagged response to transitions, with chlorophyll-a taking up to 375 m to reach the maximum values inside the pasture and up to 300 m to return to reference conditions inside the downstream forest. In the downstream forested section, diatom richness and abundance were similar to the upstream forested section but did not return to reference conditions. The results were consistent across years. Our results indicate that, while riparian forest remnants can play an important role in buffering impacts related to land-cover changes in low order streams, both the magnitude and directionality of these effects might be influenced by longitudinal effects caused by the flow of water. Riparian forest remnants can have a longitudinal effect in stream conditions, influencing environmental characteristics even over non-forested reaches, to where the forest conditions can be propagated downstream by the flow of water.

The relationship between cellular protein content and selenium accumulation in freshwater microalgae.

Variability in the bioconcentration of selenium (Se) by primary producers at the base of the food web results in uncertainty in predictions of bioaccumulation and ecological risk to higher trophic level organisms. Water chemistry, speciation of Se, and periphyton community composition have all been suggested as factors that contribute to variability in bioconcentration by primary producers; however, the role of physiological composition of periphyton species in influencing the bioconcentration of Se has not been previously evaluated. To determine if a relationship exists between algal protein content and Se accumulation, Parachlorella kessleri, Chlorella vulgaris, and Raphidocelis subcapitata were exposed to Se (as selenate) and analyzed for total protein and tissue Se content in the exponential and stationary growth phases. Protein content and Se accumulation in R. subcapitata in the stationary phase were also measured under two light intensities. No relationship between cellular protein content and Se accumulation was found for algae in the exponential phase; however, a strong relationship was found in the stationary phase among species and for R. subcapitata under differing light intensities. Absolute Se accumulations by P. kessleri, C. vulgaris, and R. subcapitata in the stationary phase were statistically different; however, the concentrations of Se in protein were similar across species. These results suggest that cellular protein content in microalgae influences Se bioconcentration and that algal protein content may improve Se bioaccumulation modeling in food webs. Integr Environ Assess Manag 2024;00:1-10. © 2024 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Loss of amphibian species alters periphyton communities in montane ponds

Amphibian larvae can affect the structure and functioning of freshwater ecosystems, but their effects have been little explored although amphibian biodiversity is rapidly declining. Given that larvae of different amphibian species belong to different trophic levels, their effects on freshwater communities and processes can be expected to differ, with herbivores likely having direct effects on algae and predators having indirect effects through trophic cascades. We explored this question through a mesocosm experiment conducted in montane ponds, using an anuran and a urodele species affected by emergent diseases. We used different scenarios of reduction and loss of one or both species, and compared them to a control scenario representing a typical amphibian community in the study area composed of four species, with total larval density held constant. Loss of the anuran resulted in lower chlorophyll concentration and algal density, likely due to replacement by more efficient grazers. Loss of the urodele produced similar trends but weaker, possibly due to an increase of invertebrate grazing activity in the absence of this predator. Our study shows how the loss of amphibian species can alter the structure of montane ponds, but also how the mechanisms involved and the intensity of effects differ for different species.

Responses of phytoplankton and periphyton community structure to an anthropic eutrophication gradient in tropical high-altitude Lake Titicaca

Eutrophication is a global environmental problem in aquatic ecosystems, mainly caused by increased nutrient loads (nitrogen and phosphorus). Phytoplankton and periphyton responses to the nutrients increase and temporal variation may be related to mutual seeding and/or variable environmental constraints. Each of these communities may be useful for characterizing and monitoring eutrophication processes. However, little information exists about the simultaneous responses or interactions between such communities during eutrophication, even less in high-altitude tropical lakes such as Lake Titicaca. Here, we first established a eutrophication gradient with stable isotopes (δ15N and δ13C) and physicochemical variables in a shallow bay of Lake Titicaca. Later, we analyzed the shifts in taxonomic and morphological forms of phytoplankton and periphyton colonizing the underwater stems of totora (Schoenoplectus californicus ssp. tatora), an emergent aquatic macrophyte, along the eutrophication gradient. There is a clear turnover (groups, genera, and morphological forms) in phytoplankton and periphyton and decreased biodiversity along the eutrophication gradient. Gomphonema genus relative abundance increase with eutrophication in both communities, while Achnanthidium abundance decreases. However, other genera behave differently in each community, allowing for the identification of specific bioindicators of eutrophication for phytoplankton (Oscillatoria, Spirogyra, and Euglena) and periphyton (Oedogonium, Stigeoclonium, and Characium). They share genus composition with some taxa showing similar behaviors, thus interactions between phytoplankton and periphyton may exist. We also believe that each compartment can act as a seeding reservoir for the other, though remaining independent to some extent.

Perikphyton Growth on Two Different Bamboo Substrate Models for Its Use in Aquaculture

Periphyton-based fish farming practices are considered low-cost technologies as they help in sustainable aquaculture production. The present study was designed to determine the efficiency of two different substrate models (viz. roof hut model and prism model) made from the bamboo sticks. The small-sized substrate models were constructed for invitro studies. The growth of periphyton was investigated on the 30th day of the experimental setup. This is the first time experimenting with bamboo substrate models. From the result it was found that the biomass of periphyton in terms of dry weight 0.03±0.01 g/cm2 was observed on both substrate models. There is no biomass difference and taxonomic difference between these two models. It may be due to the material used for the construction of the model being the same i.e. bamboo sticks and cotton thread. The taxonomic identification of the periphyton community showed the different genera of class Chlorophyceae and Bacillariophyceae. These models are efficient for periphyton growth and they also increase the productivity of periphyton due to increased surface area of substrate models. These models can be used for low-cost aquaculture.

Ecological and statistical models to configure flow regime for environment benefit in highly engineered rivers: a case study in the MacKenzie River, Southeast Australia.

Ecological and statistical models were developed using freshwater algal assemblages to assess water quality and ecological health of a regulated river. These models were used to inform configuration of flows to maintain or improve environmental conditions of the waterway whilst meeting consumptive water supply commitments. The flow regime of the MacKenzie River, western Victoria, Australia, has been substantially modified since the construction of a water supply reservoir on its upper reach in 1887. Water is withdrawn at several locations downstream of the reservoir, creating a substantially modified flow regime, impacting key environmental values of the river. To assess the impact of the different flow regimes on river health and ecosystem function, ten sites were repeatedly sampled along the river between February 2012 and April 2014. Physical and chemical characteristics of water, including pH, temperature, turbidity, electrical conductivity, dissolved oxygen, total nitrogen, total phosphorous, cations, and anions, were measured. Biological properties of the algal periphyton communities, including dry mass, ash-free dry mass, chlorophyll-a concentration, and species composition, were also measured. Exploration of the algal assemblage and water chemistry data using the computationally unconstrained ordination technique such as principal component analysis principal component analysis (PCA), correspondence analysis (CA), detrended correspondence analysis (DCA), and canonical correspondence analysis (CCA) indicated two strong gradients in the data sets. Furthermore, the quantitative ecosystem response models have been developed as the prototype tool to assist in the future configuration of flows in this river. The empirical data and models showed the lower reaches of the river to be in poor condition under low flows, but this condition improved under flows of 35 ML/day, as indicated by the reduction in green algae and cyanobacteria and improvement. Finally, the results are presented to tailor discharge and duration of water volume by amalgamation of consumptive and environmental flows to improve the condition of the stream thereby supplementing the flows dedicated to environmental outcomes.

Sorption kinetics of heavy metals from aqueous solution using Spirogyra sp.: a microcosm study

Understanding the mechanisms by which algae communities respond to disturbances in the lotic aquatic environment that is polluted by heavy metals is important, considering that algae is a biotic component of waters that acts as a producer in the aquatic food chain which has the potential to bio-magnify. This study examines the influence of time, biomass weight, heavy metal concentration, sorption capacity, and efficient removal on epilithic periphyton as a bio-accumulator of Cr, Pb, and Ni. The experiment was conducted on a laboratory scale using a canal system with a length and width of 1.2 and 1.0 meters, respectively. The canal system contains 132 L of water, has a 1.2 m2 substrate and periphyton area, a depth of 0.09 – 0.10 m, and a current flow rate of 0.04 – 0.06 m/s. The dissolved Cr6+ initial concentration in the medium was 1.64 mg/L, Pb2+ and Ni2+ concentrations were 1.4 mg/L, and the adsorption process was studied for 24 hours. Based on microscope observations and functional group interpretation utilizing infrared spectra (FTIR), the periphyton community is dominated by Spirogyra sp., which has hydroxyl (O-H), carboxyl (C-H), and carbonyl (C-C and C=O) functional groups with the ability to binding heavy metals. The remaining quantities of Cr, Pb, and Ni in water were 0.43 mg/L (removal 69.29%), 0.05 mg/L (96.43% removal), and 0.03 mg/L (97.86% removal). Periphyton has a maximal sorption capacity of 1.019 mg Cr/g, 1.97 mg Pb/g, and 1.92 mg Ni/g. The sorption kinetics of Cr, Pb, and Ni follow a pseudo-second-order model with k2 = 1.686 x 10-2 g/mg.min for Cr, 4.516 x 10-3 g/mg.min for Pb, and 2.259 x 10-2 g/mg.min for Ni, with R2 of 0.965 for Cr and 0.971 for Pb and 0.972 for Ni. Periphyton can potentially play a role as a bio-accumulator in lotic habitats, adsorbing Cr, Pb, and Ni ions, according to this study.

Mixed light photoperiod and biocide pollution affect lipid profiles of periphyton communities in freshwater ecosystems

Environmental factors, such as light intensity and exposure to contaminants, may significantly influence the lipid composition of algae in periphytic communities. In this study, we investigated the joint effects of dodecylbenzyldimethylammonium chloride (BAC 12), as biocide, and light photoperiods on the polar lipidome of a freshwater biofilm. Exposure to BAC 12 in a microcosm experiment increased the heterotrophic compartment, while phototrophic organisms were severely affected, with corresponding shifts in lipid composition. The overall decrease in polyinsaturated fatty acids suggested a significant impact of the biocide on biofilm microalgae. However, it was difficult to distinguish the influence of light from that of contamination, as there was no observable effect of photoperiod on conventional fatty acid determination. Thus, the molecular species compositions of both glycolipids and phospholipids were explored in additional multivariate analyzes. The results suggested that certain molecular species can serve as more specific markers of light duration at the biofilm scale, independently of the chemical pressure caused by other pollutants.

Using Algal Indices to Assess the Ecological Condition of the Aras River, Northwestern Iran

This work is the first in a series, and its purpose is the comprehensive assessment of the ecological state of the Aras River using biological indicators of water quality by diatoms based on species’ ecological preferences, pollution indices, statistics, and ecological mapping. Samples of diatoms and soft algae and measurements of water quality were analyzed at sixteen sampling sites (between 2020 and 2022) along the Aras River. The impact of anthropological activity on the river was monitored concerning water quality, river health, and ecosystem function. The physical and chemical characteristics of the water were measured. The biological properties of the algal periphyton communities, including species composition, were also measured. Based on the studies conducted in this research, 280 species were identified. The most prosperous species were Diatoma vulgaris, Amphora ovalis, Cocconeis placentula, Rhoicosphenia abbre-viatae, Cymbella helvetica, Brevisira arentii, Navicula tripunctata, Nitzschia linearis, Microcystis botrys, Microcystis aeruginosa, Pseudanabaena limnetica, Scenedesmus obliquus, and Pleurosira laevis (a pollution-resistant and salinity-resistant species first found in aquatic habitats in the Aras River). As a result, the empirical data and algal indices showed the river’s lower reaches to be in poor condition. Exploration of the algal assemblage and water chemistry data using computationally unconstrained ordination techniques such as principal component analysis (PCA) and canonical correspondence analysis (CCA) indicated two strong gradients in the data sets. The results support that water body classification is a function of water chemistry and biological and hydrological characteristics, as it is necessary to include pollutant effects on biota since the nature of the receiving waters influences the river’s water quality.

Influence of the antibiotic nitrofurazone on community dynamics of marine periphytic ciliates: Evidence from community-based bioassays

Marine periphytic ciliates play a pivotal role in shaping coastal ecosystems dynamics, thereby acting as robust biological indicators of aquatic ecosystem health and functionality. However, the understanding of the effects of veterinary antibiotics on composition and structure of periphytic ciliate communities remains limited. Therefore, this research investigates the influence of the veterinary antibiotic nitrofurazone on the community dynamics of marine periphytic ciliates through bioassay experiments conducted over a one-year cycle. Various concentrations of nitrofurazone were administered to the tested ciliate assemblages, and subsequent changes in community composition, abundance, and diversity were quantitatively analyzed. The research revealed significant alterations in periphytic ciliate communities following exposure to nitrofurazone. Concentration-dependent (0–8 mg L−1) decrease in ciliates abundance, accompanied by shifts in species composition, community structure, and community patterns were observed. Comprehensive assessment of diversity metrics indicated significant changes in species richness and evenness in the presence of nitrofurazone, potentially disrupting the stability of ciliate communities. Furthermore, nitrofurazone significantly influenced the community structure of ciliates in all seasons (winter: R2 = 0.489; spring: R2 = 0.666; summer: R2 = 0.700, autumn: R2 = 0.450), with high toxic potential in treatments 4 and 8 mg L−1. Differential abundances of ciliates varied across seasons and nitrofurazone treatments, some orders like Pleurostomatida were consistently affected, while others (i.e., Strombidida and Philasterida) showed irregular distributions or were evenly affected (e.g., Urostylida and Synhymeniida). Retrieved contrasting patterns between nitrofurazone and community responses underscore the broad response repertoire exhibited by ciliates to antibiotic exposure, suggesting potential cascading effects on associated ecological processes in the periphyton community. These findings significantly enhance the understanding of the ecological impacts of nitrofurazone on marine periphytic ciliate communities, emphasizing the imperative for vigilant monitoring and regulation of veterinary antibiotics to protect marine ecosystem health and biodiversity. Further research is required to explore the long-term effects of nitrofurazone exposure and evaluate potential strategies to reduce the ecological repercussions of antibiotics in aquatic environments, with a particular focus on nitrofurazone.

NEW DATA ON THE COMPOSITION OF CYANOBACTERIA AND ALGAE OF SOME WATERCOURSES OF THE KAMCHATKA PENINSULA

The results of studying the biological diversity of the fl ora of freshwater algae in some streams of the Kamchatka Peninsula are presented, the structure of algal periphyton communities is revealed and the ecological characteristics of the studied algofl ora are given. The following rivers were surveyed: Kamchatka, Andrianovka, Plotnikova, Avacha, Paratunka, Gavanka, Kirpichnaya, Karymshina, Mutnushka and the Perviy stream. As a result of sample processing, 193 species, varieties and forms of cyanobacteria and algae from fi ve divisions were found: Cyanobacteria – 5 species, Bacillariophyta – 167 taxa (taking into account varieties and forms – 177), Ochrophyta – 2, Charophyta – 4, Chlorophyta – 5. In the algae communities of the surveyed water bodies, both in terms of abundance in fouling and species diversity, diatoms prevailed. The most common species, often growing on stones and dominating in fouling, were Encyonema minutum, E. silesiacum, Hannaea arcus, Gomphonema ventricosum, Ulnaria inaequalis, Cocconeis placentula, Fragilaria capucina, Nitzschia palea. Melosira varians, Meridion circulare, Planothidium lanceolatum, Gomphonella olivacea, species of the genera Staurosira, Diatoma, Cymbella, Fragilaria and some others were most often present as subdominants. In some cases, Rhoicosphenia abbreviata, Didymosphenia geminata, and Tabularia fasciculata took the fi rst places in terms of abundance. Of the Chlorophyta Ulothrix zonata and Cladophora glomerata were found. In a number of streams Hydrurus foetidus was encountered in mass. The division of Charophyta is represented by fi laments of Spirogyra and single specimens of the genera Closterium and Cosmarium. Cyanobacteria practically did not form mass fouling, except for the Tapinothrix genus. For each surveyed area, the species composition of algae was determined and complexes of dominant species were characterized. Giving a general ecological characteristic of the studied algofl ora, it should be noted that benthic and planktonic- benthic organisms predominate in periphyton communities, which are indiff erent to water salinity and prefer a slightly alkaline habitat.

A Low-Cost Method of Measuring the In Situ Primary Productivity of Periphyton Communities of Lentic Waters.

Measuring the in situ primary productivity of periphyton during the growing season gradient can elucidate the quantitative effect of environmental drivers (mainly phosphorus concentration and light intensity) and species composition on primary productivity. Primary productivity is mainly driven by light intensity, temperature, availability of nutrients, and distribution of the ionic species of the carbonate system in the respective depths of the euphotic zone. It is a complex system that is very difficult to simulate in the laboratory. This cheap, transportable, and easy-to-build floating barge allows measuring the primary productivity accurately-directly under the actual natural conditions. The methodology is based on measuring the primary productivity in real time using noninvasive oxygen sensors integrated into tightly sealed glass jars, enabling online oxygen flux monitoring and providing new insights into metabolic activities. Detailed seasonal in situ measurements of gross primary productivity of microbial mats (or other benthic organisms) can improve current knowledge of the processes controlling primary productivity dynamics in lentic waters.

Shifts in periphyton research themes over the past three decades.

It has been well documented that periphyton communities play a key role in primary productivity, nutrient cycling, and food web interactions. However, a worldwide overview of research on the key themes, current situation, and major trends within the field is lacking. In this study, we applied the machine learning technique (latent Dirichlet allocation, LDA) to analyze the abstracts of 6690 publications related to periphyton from 1991 to 2020 based on the Web of Science database. The relative frequency of classical and basic research on periphyton related to colonization, biomass, growth rate, and habitats has been clearly decreasing. The increasing trends of research on periphyton are embodied in the periphyton function in freshwater ecosystems (e.g., application as ecological indicators, function in the removal of nutrients, and application in paleolimnology), the research at macroscales (e.g., spatial-temporal variation, and functional and taxonomic diversity), and the anthropogenic themes (e.g., climate warming, response to multiple stressors, and land use type). The keyword and title analysis showed that the periphyton studies are concentrated mainly on diatom aspects, especially with respect to streams relative to lakes. The thematic space based on non-metric multidimensional scaling (NMDS) showed that the classical themes such as growth rate, colonization, and environmental factors (e.g., multiple stressors and climate warming) were most linked to other research themes. We proposed that future trends in the periphyton should focus on the function of periphyton in lakes and their response to multiple environmental pressures with the increasingly extensive eutrophication in lakes and the increasingly significant change in the climate.

Composition, frequency and seasonal distribution of periphytic microalgae in stretches of the Curiaú River, Amapá, Eastern Amazon

Periphyton communities are composed of microorganisms loosely attached to the substrate, including fungi, bacteria, microinvertebrates, and mostly microalgae. Due to their photosynthesizing component, they are important primary producers that subsidize the aquatic trophic chain. This study aimed to verify the composition, frequency, and seasonal distribution of periphytic microalgae in stretches of the Curiaú River, located in the Environmental Protection Area (APA) of the Curiaú River, in the State of Amapá. For this, quarterly collections were carried out comprising the months of June 2016 to October 2017, during the dry and rainy seasons. The periphyton algal communities were obtained by squeezing parts of two macrophytes species, Eichhornia crassipes Mart. (Solms) and Pistia stratiotes L. The data were statistically treated using absolute values and the Kruskal-Wallis test, the latter considering the distribution of richness between sites and sampling periods (significance level of α=0.05). A total of 64 taxa were inventoried, aggregated into three taxonomic divisions: Chlorophyta (n=48; 75%), Cyanophyta (n=12; 18.75%) and Heterokontophyta (n=4; 6.25%). In class terms, Zygnematophyceae had the highest number of taxa (n=42; 65.63%), followed by Cyanophyceae (n=12; 18.75%), Chlorophyceae (n=5; 7.81%), Bacillariophyceae (n=4; 6.25%) and, finally, Ulvophyceae (n=1; 1.56%). Of the total number of inventoried taxa, 64.06% (n=41) presented sporadic frequency. Species richness was influenced by seasonality, as higher values were associated with the rainy season (p<0.05). This research is a contribution to the phycology of the Amazon region, especially in its pioneering for the state of Amapá.

THE CURRENT STATE OF HYDROBIONTS OF THE AYDAR-ARNASAY SYSTEMS OF LAKES

The material for this article was the results of many years of comprehensive studies of the current state of the biodiversity of aquatic biocenoses (phyto- and zooplankton, periphyton communities and macrophyte associations, zoobenthic organisms and ichthyofauna), the taxonomic structure and species composition of hydrobions in the Aydar-Arnasay system of lakes. During the growing season (winter-autumn) of 2019-2020, from 186 to 224 species and forms of algae were found in phytoplankton samples, where the dominant complex is diatoms, blue-green and green algae. Zooplankton is represented by 67 species, of which Rotifera - 37 species, Copepoda - 17 species, Cladocera - 13 species. Periphyton is represented by three main groups: producers (308 species of forms and varieties of algae), consumers (21 species) and decomposers (8 species), a total of 337 organisms were noted. The ichthyofauna of the lakes is represented by 18 species and subspecies of fish, of which there are 18 species in the East Arnasay Lake, 16 species in the Tuzkan Lake and 14 species in the Aydarkul Lake.