Didymosphenia Geminata Research Articles

Influence of Didymosphenia geminata Blooms on Prey Composition and Associated Diet and Growth of Brown Trout

AbstractWe compared diet, stomach fullness, condition, and growth of Brown Trout Salmo trutta among streams with or without blooms of the benthic diatom Didymosphenia geminata in the Black Hills, South Dakota. In Rapid Creek, where D. geminata blooms covered ∼30% of the stream bottom, Brown Trout consumed fewer ephemeropterans (6–8% by weight) than individuals from two stream sections that have not had D. geminata blooms (Castle and Spearfish creeks; 13–39% by weight). In contrast, dipterans (primarily Chironomidae) represented a larger percentage of Brown Trout diets from Rapid Creek (D. geminata blooms present; 16–28% dry weight) compared with diets of trout from streams without D. geminata blooms (6–19% dry weight). Diets of small Brown Trout (100–199 mm TL) reflected the invertebrate species composition in benthic stream samples; in Rapid Creek, ephemeropterans were less abundant whereas dipterans were more abundant than in streams without D. geminata blooms. Stomach fullness and condition of Brown Trout from Rapid Creek were generally greater than those of Brown Trout from other populations. Linkages among invertebrate availability, diet composition, and condition of Brown Trout support the hypothesis that changes in invertebrate assemblages associated with D. geminata (i.e., more Chironomidae) could be contributing to high recruitment success for small Brown Trout in Rapid Creek.

Aquatic nitrogen-fixing cyanobacteria associated with blooms of Didymosphenia geminata: insights from a field study

The nuisance diatom Didymosphenia geminata has recently increased in abundance worldwide and has spread through oligotrophic rivers in the South Island of New Zealand. However, it remains absent from the North Island. Its proliferation in oligotrophic environments has prompted work on phosphorus acquisition, but potential nitrogen acquisition pathways have received little attention. We partially sequenced the nifD gene, encoding a component of nitrogenase, from South Island samples containing D. geminata and compared its diversity with that of North Island sites independently ranked as high, medium and low risk for infestation. Godleyacean cyanobacteria were present in all four South Island provinces investigated, and also in three North Island sites rated medium or high risk. Most high-risk sites were dominated by Nostoc sequences, as were some infested South Island sites. Monte Carlo simulations and the weighted UniFrac metric showed that nifD diversity in low-risk North Island sites differed significantly from sites rated medium and high risk, and from infested South Island sites; however, random resampling showed that the data were insufficient to separate didymo-infested and high-risk sites from medium-risk sites. The relationships we discovered suggest that success of D. geminata in New Zealand could be mediated by indigenous nitrogen-fixing cyanobacteria.

Physicochemical predictors of the invasive diatom Didymosphenia geminata at multiple spatial scales in New Zealand rivers

Didymosphenia geminata is an alga of major concern in temperate regions due to ongoing spread and unprecedented bloom formation. The aim of this study was to identify physical and chemical habitat conditions which affect D. geminata at catchment to patch scales. To examine this, we conducted a field-based survey of 55 distinct waterways across the South Island of New Zealand. D. geminata was detected at 82 % of waterways, grew within the periphyton at 54 % and at 25 % occurred as blooms. We tested 137 variables at scales ranging from catchment to small patches. The primary predictors of D. geminata waterway presence were still waterbodies (positive effect P < 0.05) and nitrate + nitrite (negative effect P = 0.08). D. geminata biomass was best explained by increasing river stability (P < 0.01) and decreasing nitrate + nitrite concentrations (P < 0.01). A patch-scale subsidy–stress relationship was also apparent with water velocity (P < 0.05). Our large-scale survey showed D. geminata was influenced by varied conditions at multiple spatial scales, preferentially occurring and blooming within stable, lake or dam-fed oligotrophic habitats. This work supports the finding that D. geminata blooms in response to nutrient limitation; however, results here reinforce that accrual is constrained by physical processes at multiple scales.

Didymosphenia geminata in the Upper Esopus Creek: Current Status, Variability, and Controlling Factors.

In May of 2009, the bloom-forming diatom Didymosphenia geminata was first identified in the Upper Esopus Creek, a key tributary to the New York City water-supply and a popular recreational stream. The Upper Esopus receives supplemental flows from the Shandaken Portal, an underground aqueduct delivering waters from a nearby basin. The presence of D. geminata is a concern for the local economy, water supply, and aquatic ecosystem because nuisance blooms have been linked to degraded stream condition in other regions. Here we ascertain the extent and severity of the D. geminata invasion, determine the impact of supplemental flows from the Portal on D. geminata, and identify potential factors that may limit D. geminata in the watershed. Stream temperature, discharge, and water quality were characterized at select sites and periphyton samples were collected five times at 6 to 20 study sites between 2009 and 2010 to assess standing crop, diatom community structure, and density of D. geminata and all diatoms. Density of D. geminata ranged from 0–12 cells cm-2 at tributary sites, 0–781 cells cm-2 at sites upstream of the Portal, and 0–2,574 cells cm-2 at sites downstream of the Portal. Survey period and Portal (upstream or downstream) each significantly affected D. geminata cell density. In general, D. geminata was most abundant during the November 2009 and June 2010 surveys and at sites immediately downstream of the Portal. We found that D. geminata did not reach nuisance levels or strongly affect the periphyton community. Similarly, companion studies showed that local macroinvertebrate and fish communities were generally unaffected. A number of abiotic factors including variable flows and moderate levels of phosphorous and suspended sediment may limit blooms of D. geminata in this watershed.

Hydrodynamic control of benthic mats of Didymosphenia geminata at the reach scale

Algal blooms caused by the stalk-forming diatom Didymosphenia geminata impact the habitat structure and functioning of stream ecosystems. We evaluated site-specific geomorphic controls on D. geminata in a cobble bed river in the Front Range of the Rocky Mountains. Entrainment potential, defined as the ratio of mean bed shear stress to the critical shear stress, was found to be the most important control on total abundance. A comparison with critical thresholds for sediment transport showed that the requirements for flushing flows to control D. geminata blooms are similar to that required for channel maintenance. Environmental parameters influencing the morphology of the algal mats and the potential for D. geminata to dominate the benthic algal community were also investigated. The results not only contribute to understanding of the controls on benthic algal growth in dynamic streams but also for management of water releases as mitigation for the control of future blooms of D. geminata.

Influence of global change-related impacts on the mercury toxicity of freshwater algal communities

The climatic-change related increase of temperatures, are expected to alter the distribution and survival of freshwater species, ecosystem functions, and also the effects of toxicants to aquatic biota. This study has thus assessed, as a first time, the modulating effect of climate-change drivers on the mercury (Hg) toxicity of freshwater algal photosynthesis. Natural benthic algal communities (periphyton) have been exposed to Hg under present and future temperature scenarios (rise of 5°C). The modulating effect of other factors (also altered by global change), as the quality and amount of suspended and dissolved materials in the rivers, has been also assessed, exposing algae to Hg in natural river water or a synthetic medium.The EC50 values ranged from the 0.15–0.74ppm for the most sensitive communities, to the 24–40ppm for the most tolerant. The higher tolerance shown by communities exposed to higher Hg concentrations, as Jabarrella was in agreement with the Pollution Induced Community Tolerance concept. In other cases, the dominance of the invasive diatom Didymosphenia geminata explained the tolerance or sensitivity of the community to the Hg toxicity. Results shown that while increases in the suspended solids reduced Hg bioavailability, changes in the dissolved materials – such as organic carbon – may increase it and thus its toxic effects on biota. The impacts of the increase of temperatures on the toxicological behaviour of periphyton (combining both changes at species composition and physiological acclimation) would be certainly modulated by other effects at the land level (i.e., alterations in the amount and quality of dissolved and particulate substances arriving to the rivers).

Effects ofDidymosphenia geminatablooms on benthic diatom assemblages in the Restigouche River Watershed, eastern Canada

Nuisance Didymosphenia geminata (Lyngbye) M. Schmidt (didymo) blooms were first reported in 2006 from the Restigouche River Watershed (RRW), eastern Canada. Although government agencies and recreational users are concerned about these blooms, little is known about the impact on biota and (or) the structure and function of the relatively pristine riverine systems of the RRW. Here, we assess whether didymo blooms affect overall benthic diatom assemblage composition by examining epilithic samples from middle stretches of the Patapedia and Upsalquitch rivers. Significant (albeit minor) differences (P &lt; 0.05) in diatom assemblage composition between sites, with and without didymo blooms, were only observed from the Patapedia River. Rarefied diatom species diversity (Hill’s N2) and rarefied richness did not differ significantly among sites, regardless of the presence or absence of blooms. Our data show that didymo blooms have minimal effect on benthic diatom assemblage composition in the RRW.

Laboratory Handling of Didymosphenia geminata (Lyngbye) Schmidt and the Effect of Control Efforts on Viability

Didymosphenia geminata (Lyngbye) Schmidt is a type of diatom that exists in Chile as an introduced species, invading the country and its rivers. We collected samples of D. geminata from two sampling points in Chile, assessing their viability and response to control agents. Fresh D. geminata showed more than 90% of viable granular forms (containing granules in their cytoplasm); however, the dry form presents near 50% viability. By creating dry D. geminata through exposure to 38°C temperatures for 7 days, viability values of the granular form decreased to 20%. D. geminata kept at room temperature for more than 4 weeks reported values of granular forms at 50%, while samples that were refrigerated at 4°C maintained values of granular forms at 90% for 4 weeks. Previous studies suggest that high salt concentration affects the viability of D. geminata. When taking wet D. geminata samples and exposing them to a solution of 10% NaCl for 10 minutes, we observed no differences compared to the control samples, finding granular forms at 90%. When the D. geminata was exposed to a 5% soap solution, reductions of over 90% of the granular forms were observed. Our results suggest that the viability of D. geminata is associated with the granular content within their cytoplasm, and that it is possible to alter laboratory conditions for their study. These early studies are important in order to better manipulate the model in the laboratory, allowing us to obtain new evidence regarding the microalgae’s biology through in vitro studies.

Use of phosphorus to reduce blooms of the benthic diatom Didymosphenia geminata in an oligotrophic stream

Blooms of the benthic alga, Didymosphenia geminata [Lyngbye (Schmidt)], were first documented in Rapid Creek, South Dakota, in 2002 and have since been associated with changes to aquatic resources. Low concentration of P has been associated with D. geminata stalk development (i.e., blooms), so we considered elevating P as a possible method to reduce D. geminata blooms. We conducted 2 whole-stream P-enrichment experiments in Rapid Creek during 2007 and 2008. Enrichment with a slow-release fertilizer (Osmocote®: 14-14-14) in 2007 significantly reduced D. geminata blooms (indexed by D. geminata biomass) compared to upstream control sites. The reduction in biomass was less pronounced as distance from the enrichment source increased, a result indicating that P augmentation effectively decreased D. geminata biomass. In 2008, we implemented a before-after–control-impact (BACI) study to assess effects of a quick-release fertilizer (MAP: 11-52-0) on D. geminata biomass. The addition of 6 μg/L P to Rapid Creek resulted in a significant decrease in D. geminata biomass within 0.6 km downstream of the nutrient-addition point. Effects on D. geminata biomass were not evident further downstream. This study provides evidence to support the hypothesis that low P concentration regulates D. geminata blooms.

Niche dynamics and potential geographic distribution of Didymosphenia geminata (Lyngbye) M. Schmidt, an invasive freshwater diatom in Southern Chile

Aquatic invasive species are a major threat to native freshwater ecosystems and cause enormous ecological and economic damage worldwide. Didymosphenia geminata (Lyngbye) M. Schmidt is an emerging invasive aquatic species that is spreading aggressively in Southern South America. Using niche analysis and species distribution models (SDMs), we examined niche requirements of D. geminata using climatic, topographic, and biological variables. We compared the realized niche of the species in the United States (US) with the niche in Chile. Within Chile, we also examined the environmental conditions (environmental envelopes) of rivers with and without this alga, to assess whether this species has the potential to colonize more rivers. Finally, we compared the SDMs from the US and Chile projected to Chile. Results showed that the potential distribution of D. geminata varied significantly between US and Chile. The US-based model predicted a geographic distribution in Chile which ranged from 32o to 55o S latitude while the Chile-based model predicted suitable habitats only from 36° to 48o S, and not so in the coastal ranges nor in Southern Patagonia ( In Chile, we found no differences in the environmental envelopes of the invaded and uninvaded rivers, thus suggesting that this species has even more suitable habitats to invade. These results can be used for prioritizing survey sites in Southern Chile for an early detection and management of D. geminata and for the conservation of native flora and fauna in freshwater ecosystems in Chile.

Observations of two nuisance stalk-forming diatoms (Bacillariophyta) from a river in Connecticut, Northeastern U.S.A.: Didymosphenia sp. and Cymbella janischii (A. Schmidt) De Toni

The nuisance taxon Didymosphenia geminata was reported in the West Branch of the Farmington River in March, 2011 after a fisherman detected cotton-like tufts attached to rocks. In response, the Connecticut Department of Energy and Environmental Protection (CT DEEP) conducted a comprehensive survey of the river system. After major late summer storms, Didymosphenia geminata was not observed again. Surveys in 2012–2013 tracked the spatial and temporal distribution of stalk-forming diatoms at the confluence of the West Branch of the Farmington and Still Rivers, thereby allowing comparison of data from adjacent rivers with distinct water chemistries. Water chemistry and temperature data were collected to characterize nutrient concentrations associated with these diatoms. Surveys showed no evidence of Didymosphenia geminata but four native stalk-forming diatom species and a taxon previously unreported in Connecticut, Cymbella janischii, were observed throughout the year. Also from November, 2012 through June, 2013, a morphologically distinct diatom in the genus Didymosphenia was observed growing prolifically bank to bank with thick mats of long filamentous stalks. Subsequent examination revealed that the taxon previously reported as Didymosphenia geminata was instead a different taxon, Didymosphenia sp. Furthermore, Didymosphenia sp. continued to flourish in the West Branch of the Farmington River, absent from the neighbouring Still River, suggesting that the physiochemical features and in particular higher nutrients may limit the distribution of this diatom. In contrast, C. janischii was found growing abundantly further downstream in warmer water and higher nutrient levels.

Differences in benthic macroinvertebrate assemblages associated with a bloom ofDidymosphenia geminatain the Lower American River, California

Didymo (Didymosphenia geminata) is a freshwater colonial diatom native to northern latitude lakes and streams and, until recently, was considered indicative of high-altitude, low-temperature, nutrient-poor habitats experiencing little anthropogenic impact. In recent years, however, this diatom has expanded its geographic distribution into lower latitudes and altitudes. In early 2012, we discovered a bloom of didymo in the Lower American River below Nimbus Dam in Sacramento County, California. Due to production of large masses of extracellular stalks that can smother stream substrates, and its proximity to a salmonid habitat restoration project, discovery of didymo prompted us to conduct a study of its effects on benthic macroinvertebrates, an important food source for juvenile salmonids. In May and June 2012, we sampled benthic macroinvertebrates in a reach of the main channel where didymo was abundant and in a nearby reach on a side channel where environmental conditions were similar but didymo was seemingly rare or absent. We found significant differences in taxonomic composition and abundance of macroinvertebrates inhabiting the two reaches. Higher numbers of Chironomidae (midges), Gammaridae (scuds), Hirudinidae (leeches), Hydroptilidae (microcaddisflies), and total macroinvertebrates were recorded in the main channel. In contrast, higher numbers of Baetidae (baetid mayflies), Glossosomatidae (saddlecase caddisflies), and Tipulidae (crane flies), along with a higher percentage of combined Ephemeroptera, Plecoptera, and Trichoptera (%EPT), were recorded in the side channel. We also recorded higher values for three common measures of taxonomic diversity (Margalef richness, Pielou's evenness, Shannon-Wiener diversity) in the side channel. From these initial observations, we tentatively concluded that the didymo bloom has influenced benthic macroinvertebrate composition in the Lower American River.

Habitat characteristics, temporal variability, and macroinvertebrate communities associated with a mat-forming nuisance diatom (Didymosphenia geminata) in Catskill mountain streams, New York

Didymosphenia geminata has recently and rapidly greatly expanded its range and abundance, sometimes as an exotic invasive and other times as a nuisance (‘native invader’) within its hypothesized native range, including the northeastern United States. D. geminata mats are visually conspicuous and can grow >10 cm thick. Mats first appeared in the eastern Catskill mountains (New York) in 2009. Our objectives were to (1) document D. geminata growth in three impounded or regulated rivers in the eastern Catskill mountains from 2010 to 2012 and (2) measure the effects of D. geminata mats on macroinvertebrates. The highest D. geminata cell densities were downstream of reservoir outflows in two of three streams. D. geminata mat development peaked in the summer each year, but maximum coverage and cell density was variable among years. D. geminata cover was negatively correlated with 10 days maximum antecedent shear stress, and the year with lowest mean D. geminata cover had multiple tropical storms and floods, suggesting that low variation in flow allows for D. geminata mat proliferation. Across sites, D. geminata density was negatively correlated with nitrate concentrations. D. geminata density was negatively related to macroinvertebrate richness suggesting that D. geminata mats may negatively affect aquatic food webs. D. geminata appears to be a nuisance species with similar habitat characteristics and growth where it is both a native invader and an invasive species.

Influence of a tributary stream on benthic communities in a Didymosphenia geminata impacted stream in the Sierra Nevada, USA

The freshwater stalked diatom Didymosphenia geminata can alter benthic community structure. However, the numbers of D. geminata that must be present to do this is not clear. Is it possible that benthic communities in streams with D. geminata are not altered? A comparison of benthic communities in two similar, adjacent streams (one with and one without D. geminata) was conducted to identify the effects of D. geminata presence on benthic community structure. An additional comparison was made below the confluence of the two streams to determine the influence of an unregulated tributary stream on the temporal and spatial patterns of potential impacts of D. geminata on benthic communities. Benthic algal biomass (chlorophyll a and ash-free dry weight) in the D. geminata stream (dominated by D. geminata and Achnanthidium spp. throughout study period) was an order of magnitude higher. High D. geminata growth altered the physical environment of the stream benthos resulting in fewer grazing invertebrates and greater densities of burrowing invertebrates such as Chironomidae and Oligochaeta. Below the confluence, benthic community structure became more similar to the non-D. geminata stream. Results show that extensive growth of D. geminata can alter benthic communities, however, an unregulated non-D. geminata tributary stream can assuage impacts and establish benthic community structure resembling the non-D. geminata tributary stream over a relatively short distance. This study provides insight into the extent and mechanisms by which growth of D. geminata affects benthic communities and helps determine the influence of tributary stream on D. geminata growth and patterns in benthic communities.

An optimized DNA extraction protocol for benthic Didymosphenia geminata

Didymosphenia geminata mats display few cells in relation to extracellular material and contain polysaccharides and heavy metals that interfere with molecular studies. We describe an optimized DNA extraction protocol that help to overcome these difficulties. Our protocol outperformed five previously described DNA extraction techniques.

Development and validation of a quantitative PCR assay for the early detection and monitoring of the invasive diatom Didymosphenia geminata

Didymosphenia geminata is a large, invasive, freshwater diatom that can produce distinctive and robust mucilaginous stalks. Over the last two decades, there has been a worldwide increase in the distribution and severity of D. geminata blooms. These dense, persistent blooms can have severe impacts on native species and ecosystem functioning. D. geminata is usually identified by microscopic methods that are time consuming, resource intensive, and dependent upon expert taxonomic identification, so the extent of surveillance programs has been limited. As an alternative, we have developed a TaqMan quantitative polymerase chain reaction (QPCR) assay for sensitive and rapid detection and enumeration of D. geminata in environmental samples. Species-specific QPCR primers and probe were designed by aligning the D. geminata 18S ribosomal DNA (rDNA) sequence with closely related diatoms. The QPCR assay was linear (R2=1.00) over a detection range of eight orders of magnitude with a lower limit of approximately two D. geminata cells. QPCR analysis of environmental samples employed the comparative cycle threshold (CT)-method with an exogenous plasmid used as an internal reference standard. The assay was evaluated using samples collected during a survey of D. geminata in three rivers in the South Island, New Zealand, and from 13 international locations where D. geminata is known to be present. Positive QPCR amplifications were confirmed as the correct amplification product through direct DNA sequencing. Phylogenetic analysis of 18S rDNA sequences suggests that D. geminata is more closely related to species in the family Cymbellaceae rather than Gomphonemataceae as currently classified.

The Origin of Invasive Microorganisms Matters for Science, Policy, and Management: The Case of Didymosphenia geminata.

The value of distinguishing native from nonnative invasive species has recently been questioned. However, this dichotomy is important for understanding whether a species’ successful dominance is caused by introductions, changing environmental conditions that facilitate an existing population, or both processes. We highlight the importance of knowing the origin of hard-to-detect invasive microorganisms for scientific research, management, and policy using a case study of recent algal blooms of the stalk-producing diatom Didymosphenia geminata. Nuisance blooms have been reported in rivers worldwide and have been hastily attributed to introductions. However, evidence indicates that blooms are probably not caused by introductions but, rather, by environmental conditions that promote excessive stalk production by this historically rare species. Effective responses to invasive microorganisms depend on knowing whether their proliferation is caused by being nonnative or is the result of changing environmental conditions that promote invasive characteristics of native species.

Mink (Neovison vison) as a natural vector in the dispersal of the diatom Didymosphenia geminata

Considerable resources have been invested worldwide in response to the spread of the diatom Didymosphenia geminata in rivers and streams. Considering the very low possibility of elimination of an invasive microbe, management has focused on biosecurity protocols, addressed exclusively toward the human role in dispersal (e.g. ‘check, clean dry’ campaigns and gear-washing stations for recreational users). Natural dispersal by wildlife vectors may also play an important role in the spread of D. geminata and other algal species, potentially limiting or negating the efficacy of biosecurity measures. We investigated the possibility that introduced mink (Neovison vison) may be a potential dispersal agent for D. geminata and other stream diatoms in Chilean Patagonia. Neovison were trapped near a zone of strong and persistent D. geminata blooms in the fifth order Río Simpson, and also in a fourth order upstream tributary, Río Huemules, the latter with smaller, more incipient blooms. Epibiotic D. geminata cells were identified from Neovison at Río Simpson (44% positive, average 791 cells per animal, n=18 animals), and Río Huemules (20% positive, average 40 cells per animal, n=5 animals). Many other species were also observed: 20 genera, 5683 cells per mink in Río Simpson, and 18 genera, 3605 cells per mink in Río Huemules. Navicula, Epithemia, Fragilaria and Placoneis were among the genera most frequently encountered. Neovison are known to prefer the riparian ecotone of streams of all sizes, have the capacity to travel several kilometers upstream and downstream, and possibly as far as 10 km overland to colonize new catchments. Together with an estimated survival time of 60 or more days for D. geminata in a humid environment (e.g. mink fur), Neovison represent a potentially significant factor in the colonization of upstream reaches and adjacent catchments. We comment on the potential for other wildlife vectors in Patagonia, and respective alternative patterns of short- to long-distance dispersal of diatoms in continental waters. Our results suggest that wildlife vectors should be considered in the management of D. geminata, and in the case of Neovison, integrative management of multiple invasive species, and a reassessment of conservation priorities may be necessary.

Exploring the environmental context of recentDidymosphenia geminataproliferation in Gaspésie, Quebec, using paleolimnology

Management authorities often perceive Didymosphenia geminata (didymo) as an invasive, nuisance diatom species that has been introduced to eastern Canada; however, observations from early 20th century diatom surveys challenge this characterization. We apply paleolimnological techniques to place recent didymo blooms from Gaspésie, Quebec, into historical and environmental context. Sedimentary diatom assemblages were examined from Lac Humqui (a headwater lake) and Lac au Saumon (a lake with an inflowing river currently supporting blooms). The Lac Humqui assemblage experienced a broad-scale shift in their dominant life strategy with declines in fragilarioid taxa and increases in planktonic diatoms (i.e., Cyclotella–Discostella species) that began ∼1970 and increased to modern abundances ∼1990. Strong relationships between this diatom shift and increases in regional air temperatures and earlier river ice-out dates are consistent with longer growing seasons and enhanced thermal stability in Lac Humqui. Didymo was observed throughout the Lac au Saumon core, demonstrating that it has been present in the region since at least ∼1970. Our paleolimnological evidence indicates that blooms likely form in response to regional consequences of climate warming, rather than human introduction.

Nearshore benthic blooms of filamentous green algae in Lake Baikal

For the first time, species of the genus Spirogyra, non-typical of the open nearshore waters of Lake Baikal, formed algal mats with Ulothrix zonata, Ulothrix tenerrima, and Ulothrix tenuissima near the village of Listvyanka, Russia. Normally widely distributed in the 0- to 1.5-m depth range, the growth of U. zonata was now evident and dominant (63% of the biomass) in the 2- to 5-m depth range. The overgrowth of the lake bottom by filamentous green algae, changes in distributional boundaries, the emergence and mass development of species of the genus Spirogyra, the presence of the eutrophic diatom indicator Fragilaria capucina var. vaucheriae, elevated abundances of coliform bacteria, and elevated levels of nutrients suggest an early stage of cultural eutrophication in the nearshore of Lake Baikal near Listvyanka, a popular tourist destination. The unusual abundance of Fragilaria associated with the filamentous green algae consisted of long-ribbon colonies of F. capucina var. vaucheriae, a eutrophic species, wound around the filamentous green algae, enhancing the dense algae mats. Historically dominant species, such as Didymosphenia geminata, Tetraspora cylindrica var. bullosa, and Draparnaldioides baicalensis typically observed at deeper depths of Lake Baikal, are now subdominants or minor species in the nearshore along the shoreline near Listvyanka.