Periphytic Algae Research Articles

A new application of radiocarbon (14C) concentrations to stream food web analysis

We measured radiocarbon concentrations (Δ 14 C), together with stable isotope ratios (δ 13 C and δ 15 N) of aquatic animals, periphytic algae and particulate organic matter (POM) at upstream sites of two streams. We hypothesized that Δ 14 C values of organisms would be separated into two major carbon sources in streams: in-stream production (autochthonous production) and terrestrial detritus (allochthonous production). In fact, Δ 14 C values of in-stream production were low, while those of terrestrial detritus were high. This indicates the difference in sources: the former reflects the Δ 14 C values of the dissolved inorganic carbon in the catchment, whereas the latter reflects the Δ 14 C value of present atmospheric CO 2 . Δ 14 C patterns of animals differed in each of the two streams, suggesting that the role of food web structure is critical for understanding the carbon dynamics of stream ecosystems. We present, for the first time, the potential use of radiocarbon ( 14 C) in the study of food webs in stream ecosystems.

Resposta das algas perifíticas às alterações de temperatura e ao enriquecimento artificial de nutrientes em curto período de tempo

This study set out to evaluate, via a mesocosm experiment, the influence 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 25°C, and without added nutrients at 15°C. 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. The relative 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.

Periphytic algae of the Garças Lake, Upper Paraná River floodplain: comparing the years 1994 and 2004

The changes imposed by dams on hydrological regime, water transparence and nutrient concentrations downstream affect biodiversity in relation to species richness and specific composition of the community. The aim of this work was evaluate this effect on periphyton, comparing richness and composition of periphytic algae in the Garças Lake, Upper Paraná River floodplain, between the years 1994, before construction of the Porto Primavera Reservoir, and after its operation in 2004. This floodplain lake showed an increase in species, from 113 in 1994 to 159 in 2004. A few species, however, were common during the last year, dominated by Zygnemaphyceae and some Bacillariophyceae species. The increase in algal diversity in 2004 may be the result of the ability of the system to adapt to environmental changes. However, the large change in the periphyton species composition suggests further impacts on the food web, demanding continuity of long-term studies in order to determine their consequences on the biodiversity as a whole.

Effects of hydrological regime and connectivity on the interannual variation in taxonomic similarity of periphytic algae

The aim of this study was to analyze the effects of flood pulses (intensity) on the richness and composition of periphytic algae in lentic environments of the Upper Paraná River floodplain, over a six-year period. Other factors, such as connectivity of the environments with the main channel of the river and the availability of substrate for the periphyton, were also evaluated. For qualitative analyses, periphyton community was sampled from adult petioles of Eichhornia azurea Kunth taken from the littoral regions of the lakes studied. A total of 457 taxa of periphytic algae, distributed within 141 genera and 10 classes, were registered in the four environments. The greatest richness of periphytic algae was observed in connected floodplain lakes, especially in 2007 and during high water periods. In both connected and disconnected lakes, richness correlated positively with water levels of the Paraná River. Richness was also positively correlated with the number of taxa of aquatic macrophytes. The specific composition of periphytic algae differed between high and low water periods, and between connected and disconnected lakes. Therefore, among the considered variables, it is evident that flood pulse constitutes the principal force acting on periphytic algae communities of the floodplain, followed by the degree of connectivity and the presence of aquatic macrophytes.

Algas perifíticas a montante e a jusante do local de instalação de tanques-rede em tributários do reservatório de Rosana, Estado do Paraná, Brasil

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.

Sensitivity of freshwater periphytic diatoms to agricultural herbicides

The biomonitoring of pesticide pollution in streams and rivers using algae such as diatoms remains difficult. The responses of diatom communities to toxic stress in stream water are disturbed by the variations of environmental parameters. In this study, periphytic algae collected in situ were exposed under controlled conditions to two major herbicides used in French agriculture (isoproturon and s-metolachlor). Three exposure regimes were tested: 5 and 30 μg L −1 for 6 days and 30 μg L −1 for 3 days followed by a recovery period of 3 days. The algal biomasses were assessed from pigment concentrations (chlorophyll a and c) and from live cell density. The highest concentration (30 μg L −1) of isoproturon inhibited the biomass increase statistically significantly. In periphyton exposed to 5 and 30 μg L −1 of s-metolachlor, chlorophyll c concentration and live cell density were also statistically significantly lower than in the control. Periphyton left to recover after reduced exposure duration (3 days) showed higher growth rates after treatment with s-metolachlor than with isoproturon. Taxonomic identifications showed that species like Melosira varians, Nitzschia dissipata and Cocconeis placentula were not affected by the herbicide exposure. Other species like Eolimna minima and Navicula reichardtiana were more sensitive. Studying diatoms according to their trophic mode showed that facultative heterotroph species were statistically significantly favoured by isoproturon exposure at the highest concentration. Results obtained with s-metolachlor exposure showed a disturbance of cell multiplication rather than that of photosynthesis. These results suggest that photosynthesis inhibitors like isoproturon favour species able to survive when the autotroph mode is inhibited.

Extrinsically and intrinsically generated spatial patterns of algal abundance in an experimental stream

Spatial heterogeneity in species abundance arises from both extrinsic (largely abiotic) and intrinsic (largely biotic) processes. The relative importance of these two types of processes can vary across ecological systems and across temporal and spatial scales. Numerous empirical studies have explored spatial patterns resulting from extrinsic and intrinsic processes, however the interaction of these two types of processes can result in complex patterns that are difficult to test. We used a unique model system consisting of periphytic algae grown on agar in an experimental stream to manipulate an extrinsic and an intrinsic process. We manipulated an extrinsic process by varying the spatial arrangement of nutrients creating both heterogeneous and homogeneous environments for the algae. We manipulated an intrinsic process by introducing a snail herbivore to the system. The resulting spatial algal patterns showed that both types of processes were important in producing spatial abundance patterns and that the patterns occurred at two distinct spatial scales in our system. At the scale of the imposed nutrient heterogeneity, algae “tracked” the differences in nutrient supply rates. The snail herbivores both reduced and promoted spatial patterns in algal abundance at different spatial scales reflecting their species-specific foraging behavior. An ability to detect differences in algal abundance allowed the snails to reduce the power of patterns at the scale of the imposed nutrient heterogeneity; however below a spatial scale of approximately 30 mm the snails could no longer detect differences in algal abundance and so foraged randomly. At this spatial scale the spatial heterogeneity in algal abundance increased and the resulting algal patterns were relatively spatially fixed through time. We suggest that this relative constancy may arise in part from a detected weak Allee effect in algal growth rates.

Characterization of periphytic algae from Macheta and Paipa thermal springs, Colombia

Characterization of periphytic algae from Macheta and Paipa thermal springs, Colombia

What does stable isotope analysis reveal about trophic relationships and the relative importance of allochthonous and autochthonous resources in tropical streams? A synthetic study from Hong Kong

Summary1. Analysis of the stable isotope signatures of carbon (C) and nitrogen (N) of foods and consumers has led to some preliminary understanding of the relative importance of autochthonous and allochthonous resources in tropical streams. However, robust generalizations about the dynamics of food webs in these habitats, and their response to shading gradients or season, are still lacking. In addition, the feasibility of employing a baseline δ15N value for estimating trophic positions (TPs) of consumers in small tropical streams has yet to be explored.2. We analysed data on stable isotope signatures of food sources and aquatic consumers obtained from 14 studies carried out in small streams in monsoonal Hong Kong (22°30′N, 114°10′E) between 1996 and 2006. Emphasis was placed on determining the relative importance of leaf litter and autochthonous foods in supporting consumer biomass, and the extent to which trophic base and TP vary among streams and seasons.3. Although allochthonous leaf litter was generally 13C‐ and 15N‐depleted relative to autochthonous foods, there were marked isotopic shifts of food sources and consumers in response to season (dry versus wet) and stream shading. Consumer taxa were generally more 13C‐ and 15N‐enriched in the unshaded streams, but seasonal effects were more variable. Despite these changes, there was consistent evidence that stream food webs were based on periphytic algae and/or cyanobacteria with leaf litter serving as a minor food.4. Heptageniidae (Ephemeroptera), Tipulidae (Diptera), Elmidae (Coleoptera) and shrimps (Atyidae) were used as a baseline for calculating the TPs of other consumer taxa. The maximum TPs in shaded streams remained fairly constant between seasons (dry = 3.93; wet = 3.97), while those in unshaded streams were higher and showed seasonal fluctuations (dry = 5.13; wet = 4.39).5. Although variations in consumer isotope signatures in response to season and shading gradients did not confound our interpretation of the stream food base, changes in consumer δ15N did affect the calculation of consumer TPs. Misleading estimates of consumer TPs are likely if samples are collected from a narrow range of streams and/or during one season. Overestimation of the TPs of specialist herbivores (e.g. fish grazers) is also possible when autochthonous resources are substantially more 15N‐enriched than allochthonous foods.

Algas perifíticas em dois ambientes do baixo rio Doce (lagoa Juparanã e rio Pequeno – Linhares, Estado do Espírito Santo, Brasil): variação espacial e 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 that predominated 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 also presented a greater number of significant correlations with the biological variables, showing evidence of temporal heterogeneity.

Effects of addition of tilapia Oreochromis niloticus and substrates for periphyton developments on pond ecology and production in C/N-controlled freshwater prawn Macrobrachium rosenbergii farming systems

The present research investigated the effect of addition of tilapia and substrates for periphyton development on pond ecology, production and economic performances in C/N controlled freshwater prawn farming system. The absence and presence (0 and 0.5 individual m − 2 ) of tilapia were investigated in 40 m 2 ponds stocked with 3 prawn juveniles (individual weight 5 g) m − 2 with or without added substrates for periphyton development. A locally formulated and prepared feed containing 30% crude protein (C/N ratio10) was applied daily, initially at 10% of the prawn stocked biomass and was gradually reduced to 3% of prawn biomass. Tapioca starch was used as carbohydrate source for increasing the C/N ratio from 10 (as in feed) to 20 and was applied to the water column separately from the feed. Addition of periphyton substrates significantly reduced the inorganic N-species (NH 3–N, NO 2–N and NO 3–N) in the water column. It decreased the abundance of plankton in the overlying water and increased the abundance of benthic macroinvertebrates. The abundance of periphytic algae and periphyton biomass (dry matter, ash free dry matter and chlorophyll a) were significantly higher in tilapia free ponds compared to tilapia added ponds. Both substrates and tilapia had significant effects on feed conversion ratio (FCR) of freshwater prawn: substrates decreased FCR by 14% while tilapia addition increased it by 16%. The addition of substrates did not influence prawn and tilapia size at harvest but improved the survival of prawn from 54 to 77%. Substrates contributed 44% and 19% higher net yield of prawn and tilapia, respectively whereas tilapia addition decreased the net yield of prawn by 14%. The economic analysis showed that addition of tilapia and periphyton substrates jointly improved the benefit–cost ratio. Addition of tilapia and periphyton substrates in C/N controlled system benefited the freshwater prawn culture practices through (1) reducing toxic inorganic nitrogenous compounds in water (2) enhancing the utilization of natural foods (3) improving survival, production and economic benefit.

Temporal changes in the periphytic algal communities in a drowned tropical forest reservoir in Malaysia: Lake Kenyir

AbstractPeriphytic algal assemblages, comprising bacillariophytes, cyanophytes and chlorophytes of standing dead trees in Lake Kenyir, a tropical drowned forest reservoir, were studied during 1995. A total of 317 algal taxa were identified in this study. The monthly floral mean species richness and cell count data demonstrated significant temporal differences between the months, in one‐way anova (P < 0.05). Both redundancy analysis and cluster analysis on monthly blue‐green abundance and diatom assemblages exhibited conspicuous groupings among the months, with underpinning seasonal differences. The responses were not similar, however, between the upstream and downstream ends of the lake. The grouping or clustering of months can be generalized as: (i) November, December and January as the monsoonal months; (ii) February, March, April and May as the transitional months; and (iii) June to October as the dry months. Based on stepwise multiple regression with forward selection, alkalinity and dissolved oxygen concentration were significant environmental predictors at the downstream dam sampling site, and reactive silica, electrical conductivity, Secchi depth transparency and sunshine hours were significant predicators at the upstream riverine sampling site, based on Monte Carlo tests. Being a ploymictic, mesotrophic lake, the limnology and temporal changes for Lake Kenyir appears to be complex and driven by monsoons, as evidenced from the temporal changes in its periphytic algae communities, particularly the diatom assemblages. The downstream sampling site (site 1) at the dam, in the main basin and deeper zone of the lake, the seasonal amplitude was likely complex because of thermocline formation and stratification processes. In contrast, the upstream sampling site in the Petang River (site 2) exhibited a clearer distinction between the dry and monsoon months, based on its cyanophyte and diatom floral assemblages. These study results are pertinent for lake management, especially for developing biomonitoring programmes or lake productivity studies, as well as for climate change studies, within the context of tropical lake ecology.

The influence of a toxic cyanobacterial bloom and water hydrology on algal populations and macroinvertebrate abundance in the upper littoral zone of Lake Krugersdrift, South Africa

The biological interactions and the physical and chemical properties of the littoral zone of Lake Krugersdrift were studied for a 4-month period when a dense, toxic cyanobacterial bloom dominated by Microcystis aeruginosa was present in the main lake basin. The presence of a toxic strain of M. aeruginosa was confirmed through the use of ELISA and molecular markers that detect the presence of the mcyB and mcyD genes of the mcy gene cluster that synthesizes microcystin. An increase in Microcystis toxicity at sites dominated by the cyanobacterial scum was accompanied by an increase in total abundance of the macroinvertebrate families Hirudinae, Chironomidae, and Tubificidae. Sites located away from the cyanobacterial scum had a lower abundance but a higher diversity of macroinvertebrates. The water quality under the Microcystis scum was characterized by low pH values, low concentrations of dissolved oxygen, and lower total alkalinity values. The periphytic alga Ulothrix zonata was absent in areas dominated by the cyanobacterial scum, possibly as a result of overshadowing by the scum or direct toxic allelopathic effects on growth and photosynthesis. The diatom Diatoma vulgare dominated the benthic algal flora beneath the cyanobacterial scum.

Does rock chemistry affect periphyton accrual in streams?

Stones of different rock types often accrue different amounts of periphytic algae. Although algal biomass may be positively related to stone roughness, the confounding role of rock chemistry is unclear. This independent effect of rock chemistry on benthic algae was tested using the nutrient-diffusing technique, by incorporating powdered stone, rather than nutrients, into the agar matrix. Rocks tested were sandstone, obsidian, schist, greywacke, pumice, gypsum, limestone, serpentine, and phosphorite. Petri-dishes containing powdered rock and agar, and covered with a permeable cellulose filter, were incubated in eight pools in a granitic stream. Algal biomass did not differ among any of the nine rock types and plain agar control, whereas biomass differed among the concurrently placed nutrient diffusing substrates (the stream was phosphorus-limited). Algal composition was more related to an upstream-downstream gradient (for filamentous algae) and pool-specific effects (deposition of fine sediment for diatoms) than rock chemistry. This minimal effect of rock chemistry may be caused by the low dissolution rate of stones.

Algal Growth Response in Two Illinois Rivers Receiving Sewage Effluent

ABSTRACT Phosphorus (P) primarily enters streams in Illinois as effluent released from sewage treatment plants and runoff from agricultural fields. As a result, water quality can be affected and large amounts of algal growth are possible. We determined the growth of periphytic algae (as chla) relative to differing amounts of P (factor of 10) released in sewage effluent in two rivers. The Salt Fork Vermilion River and the Copper Slough branch of the Kaskaskia River both have a sewage treatment plant near their sources. Periphytic algal growth was assayed in each river with unglazed ceramic tiles (five week period) at 10 sites, each 10 km apart downstream from where the treatment plant was located. Field measurements included canopy cover, turbidity, water depth (to the tile surface), and water temperature. The concentrations of sestonic algae (as chla), total P, dissolved reactive P, nitrate-N, dissolved organic carbon, and Si were determined in water samples. Total P concentrations were different between the two rivers, ranging from 1.9 mg L−1 just below the Salt Fork Vermilion River plant to 0.67 mg L−1 90 km downstream; corresponding values were 0.19 and 0.16 mg L−1 for the Kaskaskia River. Phosphorus concentrations were not related to sestonic or tile periphytic chla in either river. Canopy cover, turbidity, and unstable sediments apparently regulated algal growth by limiting the penetration of light. Therefore, P was not the primary regulator of algal growth, and removing sewage effluent P from these rivers is unlikely to alter algal growth.

Competition, predation and flow rate as mediators of direct and indirect effects in a stream food chain

Using semi-natural stream channels, we estimated the effects of competition and predation exerted by juvenile and adult exotic rainbow trout (Oncorhynchus mykiss) on the diel activity pattern of juvenile native Atlantic salmon (Salmo salar), a secondary consumer. We also evaluated the direct and indirect effects of competition, predation and abiotic factors (water depth and velocity) on the growth rate of salmon, the biomass of invertebrate grazers (primary consumers) and the biomass of periphytic algae (primary producers; chlorophyll a). The presence of chemical cues emanating from adult predatory trout reduced the daily activity of juvenile Atlantic salmon. In contrast, competition imposed by juvenile rainbow trout forced Atlantic salmon to be more active during the day, even if adult rainbow trout were also present. We found no effect of either competition or of predatory cues on the growth rate of Atlantic salmon, and no evidence of indirect effects on either the biomass of invertebrates or the biomass of chlorophyll a. In contrast, we demonstrated that this food chain (fish--invertebrate grazers--periphytic algae) was under the control of a critical abiotic factor, the water velocity, and of bottom-up processes. We concluded that the exotic species directly increases the risk of predation of the native Atlantic salmon, but behavioral compensation probably limits the effects on growth rate. The competition and predation imposed by the invaders had no indirect effects on lower trophic levels. Top-down effects may have been mitigated by the dominant influence of water velocity controlling all components of the food chain and by elevated levels of primary production.

Diversity and Distribution of Algae in Wetlands of the Rio Grande do Sul, Brazil

Surveys of algae diversity and distribution involving the Rio Grande do Sul State was completely unknown. The main goals of this study were to analyze the richness and distribution of the algae genera in wetlands of Rio Grande do Sul and to compare the algal composition among five geomorphologic provinces and between different wetland classes and types. A total of 146 wetlands were sampled within the five geomorphologic provinces of Rio Grande do Sul: Coastal Plain, Central Depression, Cristaline Shield, Highlands and Pampas. One single visit took place in each wetland from March to October 2002. A total of 107 genera of algae were found, distributed along five divisions: Cyanophyta, Heterokontophyta, Dinophyta, Euglenophyta, and Chlorophyta. The highest number of genera was found in Chlorophyta (52). Most of the observed genera presented a sporadic and occasional distribution in the wetlands of Rio Grande do Sul. The wetland algal composition of Cristaline Shield, Central Depression and Pampas was similar. While the planktonic algae were more associated with the aquatic bed vegetation (Gymnodinium, Scenedesmus and Ankistrodemus), and permanent wetlands (Dictyosphaerium and Ankistrodesmus), the periphytic algae were more associated with the emergent vegetation (Oscillatoria and Encyonema), and intermittent wetlands (Nostoc). The results showed a high richness and wide geographic distribution of the algae in wetlands of Rio Grande do Sul.

Algas do perifíton de distintos ambientes na planície de inundação do alto rio Paraná

This paper analyses the structure and dynamic of the periphytic algae community in three systems in the Parana river floodplain (Guarana lagoon, Fechada lagoon and Baia river), in two hydrologic periods (high waters and low waters) in 2003. Utilized substratum was Eichhornia azurea Kunth. There were found a total of 284, 193 in high waters and 172 in low waters periods. The Guarana lagoon presented the largest richness in both hydrologic periods. The high waters period (March) had larger density of cyanobacteria. The low waters period (September) had larger occurrence of diatoms. The limnological characteristics (mainly dissolved oxygen, orthophosphate and nitrogen forms) were influenced by hydrologic level and hydrodynamics characteristics, which interfered in presence, abundance, and distribution of the algae in the system.

Marine sediments tell it like it was

We live in a constantly changing environment. Although some changes are natural and therefore beyond our control, there is no question that many anthropogenic activities have dramatically altered our planet. The “human footprint” is now discernable around the globe, so much so that Crutzen (1) proposed a new geological epoch (the Anthropocene) to delineate the recent human-dominated era of Earth's history. The list of environmental problems that can be related to cultural activities continues to grow, including ecosystem changes linked to climatic warming from elevated greenhouse gas emissions, acidic precipitation, industrial pollutants, invasions of exotic species, as well as many other environmental insults. While new problems continue to be recognized, perhaps the oldest and most commonly reported water quality problem is anthropogenic eutrophication, or the overfertilization of waters by excessive nutrient inputs (especially nitrogen and phosphorus). Typically, anthropogenic nutrient sources can be divided into point and nonpoint sources. Point sources include those with easily defined origins, such as a sewage pipe or nutrient-rich industrial effluent from a factory. Nonpoint or diffuse sources, such as agricultural runoff from fertilized fields, are more difficult to control. Nutrients are of course essential for biological growth; however, excessive enrichment can result in numerous undesirable effects, such as increased algal blooms (including some toxic forms), excessive growths of certain aquatic macrophytes and periphytic algae (with the displacement of other biota), taste and odor complaints, decreased oxygen levels in deeper waters (which can eventually result in fish kills and the extirpation of some benthic species), and major shifts in food web structures and biogeochemical changes in both the water column and sediments. Loss of ecosystem services, as well as declines in fisheries and tourism, can also have many social, health, and economic ramifications. Daunting challenges become evident, however, when one attempts to track and study these … *E-mail: smolj{at}queensu.ca

Periphyton-based water quality analysis of a large river (River Danube, Hungary): exploring the potential of molecular fingerprinting for biomonitoring

Water quality monitoring based on microscopical analysis of periphytic algae is fundamental to the European Water Framework Directive. However, the outcome of this kind of monitoring is often dependent on the experience of the operating taxonomist and the availability of an electron microscope for fine-scale taxonomic analysis. Furthermore, it is hampered by the insufficiencies of the morphology-based diatom taxonomy. Molecular fingerprinting methods have the potential to evade these problems and serve as a complementary tool in biomonitoring studies. To test this concept, periphyton of the River Danube was monitored for a period of six months using microscopical and molecular fingerprinting (terminal restriction fragment length polymorphism) methods in parallel. We identified 120 diatom taxa by light and electron microscopy, and diatom-based water quality using Omnidia Version 4 software was found to be good or moderate (IPS value between 12 and 16). The number of operational taxonomic units identified by terminal restriction fragment length polymorphism analysis of the 18S rRNA gene ranged from 7 to 29 for individual samples, and was in total 88 in the Mspl digest and 33 in the Rsal digest. The results of both analyses were compared by hierarchical classification and we found good correlation between the two methods. We propose, that after further development of molecular databases and methodology, molecular fingerprinting may have the potential to be implemented for routine biomonitoring purposes.