Nutrient limitation of benthic algae in Lake Baikal, Russia

Ozersky, Ted; Volkova, Ekaterina Alexandrovna; Бондаренко, Н. А.; Тимошкин, О. А.; Malnik, V. V.; Domysheva, V. M.; Hampton, Stephanie E.

doi:10.1086/699408

Cited by 19 publications

(15 citation statements)

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“…Such eutrophication is causing large blooms of filamentous green algae to form, often far from local sources of pollution (including Spirogyra spp. and Stigeoclonium tenue ), which then rot along the coastlines [36, 37, 69]. As yet there is no chemical monitoring evidence to suggest that littoral eutrophication has spread into the pelagic regions of lake (e.g.…”

Section: Discussionmentioning

confidence: 99%

Diatom evidence of 20th century ecosystem change in Lake Baikal, Siberia

et al. 2018

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Lake Baikal has been experiencing limnological changes from recent atmospheric warming since the 1950s, with rising lake water temperatures, reduced ice cover duration and reduced lake surface-water mixing due to stronger thermal stratification. This study uses lake sediment cores to reconstruct recent changes (c. past 20 years) in Lake Baikal’s pelagic diatom communities relative to previous 20th century diatom assemblage records collected in 1993 and 1994 at the same locations in the lake. Recent changes documented within the core-top diatom records agree with predictions of diatom responses to warming at Lake Baikal. Sediments in the south basin of the lake exhibit clear temporal changes, with the most rapid occurring in the 1990’s with shifts towards higher abundances of the cosmopolitan Synedra acus and a decline in endemic species, mainly Cyclotella minuta and Stephanodiscus meyerii and to a lesser extent Aulacoseira baicalensis and Aulacoseira skvortzowii. The north basin, in contrast, shows no evidence of recent diatom response to lake warming despite marked declines in north basin ice cover in recent decades. This study also shows no diatom-inferred evidence of eutrophication from deep water sediments. However, due to the localised impacts seen in areas of Lake Baikal’s shoreline from nutrient pollution derived from inadequate sewage treatment, urgent action is vital to prevent anthropogenic pollution extending into the open waters.

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Section: Discussionmentioning

confidence: 99%

Diatom evidence of 20th century ecosystem change in Lake Baikal, Siberia

et al. 2018

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“…Nutrient limitation of benthic algae has been documented in a variety of systems including streams (Ziegler & Lyon, 2010), lakes (Ozersky et al., 2018), and wetlands (Cooper et al., 2016). Algae in freshwater ecosystems are often co‐limited by both N and P (Elser et al., 1990), and these nutrients have been shown to relieve nutrient limitation of benthic algae within wetlands located along the Tanana River floodplain (Wyatt & Turetsky, 2015).…”

Section: Discussionmentioning

confidence: 99%

“…Compared to our understanding of biofilm ecology in rivers (Battin et al., 2016; Bechtold et al., 2012; Wagner et al., 2017) and lakes (Ozersky et al., 2018; Wyatt et al., 2019), our knowledge of microbial interactions within wetlands is lacking (Halvorson et al., 2020). This knowledge gap is particularly evident in peatlands, a dominant wetland type at northern latitudes (Kolka et al., 2018).…”

Section: Introductionmentioning

confidence: 99%

Carbon subsidies shift a northern peatland biofilm community towards heterotrophy in low but not high nutrient conditions

2020

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Producer–decomposer interactions within aquatic biofilms can range from mutualistic associations to competition depending on available resources. The outcomes of such interactions have implications for biogeochemical cycling and, as such, may be especially important in northern peatlands, which are a global carbon sink and are expected to experience changes in resource availability with climate change. The purpose of this study was to evaluate the effects of nutrients and organic carbon on the relative proportion of primary producers (microalgae) and heterotrophic decomposers (bacteria and fungi) during aquatic biofilm development in a boreal peatland. Given that decomposers are often better competitors for nutrients than primary producers in aquatic ecosystems, we predicted that labile carbon subsidies would shift the biofilm composition towards heterotrophy owing to the ability of decomposers to outcompete primary producers for available nutrients in the absence of carbon limitation. We manipulated nutrients (nitrate and phosphate) and organic carbon (glucose) in a full factorial design using nutrient‐diffusing substrates in an Alaskan fen. Heterotrophic bacteria were limited by organic carbon and algae were limited by inorganic nutrients. However, the outcomes of competitive interactions depended on background nutrient levels. Heterotrophic bacteria were able to outcompete algae for available nutrients when organic carbon was elevated and nutrient levels remained low, but not when organic carbon and nutrients were both elevated through enrichment. Fungal biomass was significantly lower in the presence of glucose alone, possibly owing to antagonistic interactions with heterotrophic bacteria. In contrast to bacteria, fungi were stimulated along with algae following nutrient enrichment. The decoupling of algae and heterotrophic bacteria in the presence of glucose alone shifted the biofilm trophic status towards heterotrophy. This effect was overturned when nutrients were enriched along with glucose, owing to a subsequent increase in algal biomass in the absence of nutrient limitation. By measuring individual components of the biofilm and obtaining data on the trophic status, we have begun to establish a link between resource availability and biofilm formation in northern peatlands. Our results show that labile carbon subsidies from outside sources have the potential to disrupt microbial coupling and shift the metabolic balance in favour of heterotrophy. The extent to which this occurs in the future will probably depend on the timing and composition of bioavailable nutrients delivered to surface waters with environmental change (e.g. permafrost thaw).

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“…Finally, compositional shifts may mediate nutrient-driven effects on production (Guasch, Marti, & Sabater, 1995;Marcarelli & Wurtsbaugh, 2006), since different algal taxa have different photosynthetic rates (Edwards, Thomas, Klausmeier, & Litchman, 2015;Underwood et al, 2005). For example, in several studies, Stigeoclonium tenue increased in abundance in terms of cell counts and/or biovolume under N and P enrichment (Fairchild et al, 1985;Marks & Lowe, 1989;Ozersky et al, 2018), but, because this species has relatively low biomass-specific productivity compared to other algae (e.g. diatoms) (Rosemond & Brawley, 1996), this compositional shift could potentially reduce production compared to a community with similar overall biomass but an alternate assemblage.…”

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confidence: 99%

Responses of benthic algae to nutrient enrichment in a shallow lake: Linking community production, biomass, and composition

2019

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Understanding how nutrient limitation affects algal biomass and production is a long‐standing interest in aquatic ecology. Nutrients can influence these whole‐community characteristics through several mechanisms, including shifting community composition. Therefore, incorporating the joint responses of biomass, taxonomic composition, and production of algal communities, and relationships among them, is important for understanding effects of nutrient enrichment. In shallow subarctic Lake Mývatn, Iceland, benthic algae compose a majority of whole‐lake primary production, support high secondary production, and influence nutrient cycling. Given the importance of these ecosystem processes, the factors that limit benthic algae have a large effect on the function and dynamics of the Mývatn system. In a 33‐day nutrient enrichment experiment conducted in Lake Mývatn, we measured the joint responses of benthic algal biomass, primary production, and composition to nitrogen (N) and phosphorus (P) supplementation. We enriched N and P using nutrient‐diffusing agar overlain by sediment, with three levels of N and P that were crossed in a factorial design. We found little evidence of community‐wide nutrient limitation, as chlorophyll‐a concentrations showed a negligible response to nutrients. Gross primary production (GPP) was unaffected by P and inhibited by N enrichment after 10 days, although the inhibitory effect of N diminished by day 33. In contrast to biomass and primary production, community composition was strongly affected by N and marginally affected by P, with some algal groups increasing and others decreasing with enrichment. The taxa with the most negative and positive responses to N enrichment were Fragilariaceae and Scenedesmus, respectively. The abundances of particular algal groups, based on standardised cell counts, were related to GPP measured at the end of the experiment. Oocystis was negatively associated with GPP but was unaffected by N or P, while Fragilariaceae and Scenedesmus were positively associated with GPP but had opposite responses to N. As a result, nutrient‐induced compositional shifts did not alter GPP. Overall, our results show that nutrient enrichment can have large effects on algal community composition while having little effect on total biomass and primary production. Our study suggests that nutrient‐driven compositional shifts may not alter the overall ecological function of algal communities if (1) taxa have contrasting responses to nutrient enrichment but have similar effects on ecological processes, and/or (2) taxa that have strong influences on ecological function are not strongly affected by nutrients.

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Nutrient limitation of benthic algae in Lake Baikal, Russia

Cited by 19 publications

References 58 publications

Diatom evidence of 20th century ecosystem change in Lake Baikal, Siberia

Diatom evidence of 20th century ecosystem change in Lake Baikal, Siberia

Carbon subsidies shift a northern peatland biofilm community towards heterotrophy in low but not high nutrient conditions

Responses of benthic algae to nutrient enrichment in a shallow lake: Linking community production, biomass, and composition

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