Taxonomic Structure and Productivity of Phytoplankton Assemblages in Crater Lake, Oregon

McIntire, C. David; Larson, Gary L.; Truitt, Robert E.; Debacon, Mary K.

doi:10.1080/07438149609354072

Cited by 28 publications

(27 citation statements)

References 30 publications

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“…It has been observed that distinct assemblages of phytoplankton coexist in a given water column in oligotrophic systems (Venrick 1982;McIntire et al 1996;Moore and Chisholm 1999). Our model suggests a quantitative criterion: a species occurs in highest abundance in the vertical where its species-specific growth and loss rates balance.…”

Section: Discussionmentioning

confidence: 94%

“…Using a 25-cm path-length WetLabs ac-9, we measured beam attenuation by particles at 650 nm and estimated the chlorophyll concentration from the difference in absorption at 676 and 650 nm (Davis et al 1997;Chang and Dickey 2001). Conventional measurements of phytoplankton biovolume and chlorophyll concentration were obtained from bottle samples as described in McIntire et al (1996) and are available for biweekly periods from 1989 to 2000 for June-September. Measurements of nitrate and organic nitrogen were obtained as described in Larson et al (1996) for the same period.…”

Section: Methodsmentioning

confidence: 99%

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Subsurface maxima of phytoplankton and chlorophyll: Steady‐state solutions from a simple model

Fennel

Boss

2003

Limnology & Oceanography

250

208

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In oligotrophic lakes and oceans, the deep chlorophyll maximum may form independently of a maximum of phytoplankton biomass, because the ratio of chlorophyll to phytoplankton biomass (in units of carbon) increases with acclimation to reduced light and increased nutrient supply at depth. Optical data (beam attenuation as proxy for phytoplankton biomass and chlorophyll fluorescence and absorption as proxies for chlorophyll concentration) and conventional measurements of biovolume, particulate organic carbon, and chlorophyll from two oligotrophic systems (Crater Lake, Oregon, and Sta. ALOHA in the subtropical North Pacific Ocean) are presented and show a vertical separation of the maxima of biomass and chlorophyll by 50-80 m during stratified conditions. We use a simple mathematical framework to describe the vertical structure of phytoplankton biomass, nutrients, and chlorophyll and to explore what processes contribute to the generation of vertical maxima. Consistent with the observations, the model suggests that biomass and chlorophyll maxima in stable environments are generated by fundamentally different mechanisms. Maxima in phytoplankton biomass occur where the growth rate is balanced by losses (respiration and grazing) and the divergence in sinking velocity, whereas the vertical distribution of chlorophyll is strongly determined by photoacclimation. A deep chlorophyll maximum is predicted well below the particle maximum by the model. As an interpretation of these results, we suggest a quantitative criterion for the observed coexistence of vertically distinct phytoplankton assemblages in oligotrophic systems: the vertical position at which a species occurs in highest abundance in the water column is determined by the ''general compensation depth''-that is, the depth at which specific growth and all loss rates, including the divergence of sinking/swimming and vertical mixing, balance. This prediction can be tested in the environment when the divergence of sinking and swimming is negligible.

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Section: Discussionmentioning

confidence: 94%

Section: Methodsmentioning

confidence: 99%

Subsurface maxima of phytoplankton and chlorophyll: Steady‐state solutions from a simple model

Fennel

Boss

2003

Limnology & Oceanography

250

208

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“…Crater Lake is a deep, nitrogen-limited lake with a relatively low density of bacterioplankton (25,27,44). Its ultraoligotrophic status has likely selected for obligately oligotrophic organisms and organisms able to switch between heterotrophy and phototrophy as light availability and organic carbon levels fluctuate.…”

Section: Discussionmentioning

confidence: 99%

“…It is the deepest lake (589 m) in the United States and is remarkably clear, with primary productivity limited by nitrogen and trace metal availability. An ongoing NPS commitment to research at Crater Lake has resulted in a wealth of readily available limnological data (24,25,27,28). A detailed description of Crater Lake's bacterioplankton community based on 16S rRNA gene cloning and in situ hybridization was published in 2001 (44).…”

mentioning

confidence: 99%

Representative Freshwater Bacterioplankton Isolated from Crater Lake, Oregon

Page

Connon

Giovannoni

2004

Appl Environ Microbiol

101

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High-throughput culturing (HTC) methods that rely on dilution to extinction in very-low-nutrient media were used to obtain bacterial isolates from Crater Lake, Oregon. 16S rRNA sequence determination and phylogenetic reconstruction were used to determine the potential ecological significance of isolated bacteria, both in Crater Lake and globally. Fifty-five Crater Lake isolates yielded 16 different 16S rRNA gene sequences. Thirty of 55 (55%) Crater Lake isolates had 16S rRNA gene sequences with 97% or greater similarity to sequences recovered previously from Crater Lake 16S rRNA gene clone libraries. Furthermore, 36 of 55 (65%) Crater Lake isolates were found to be members of widely distributed freshwater groups. These results confirm that HTC is a significant improvement over traditional isolation techniques that tend to enrich for microorganisms that do not predominate in their environment and rarely correlate with 16S rRNA gene clone library sequences. Although all isolates were obtained under dark, heterotrophic growth conditions, 2 of the 16 different groups showed evidence of photosynthetic capability as assessed by the presence of puf operon sequences, suggesting that photoheterotrophy may be a significant process in this oligotrophic, freshwater habitat.

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“…Phytoplankton were preserved with Lugol's solution and concentrated by gravity settling (96 h total). Cells Ͼ1 m were identified and counted by means of an inverted microscope, and biovolume conversion factors were determined for each taxon by geometric approximation (McIntire et al 1996). Phytoplankton biovolumes reported for broad taxonomic groups are sums of determinations for several species, each scaled by an appropriate conversion factor.…”

Section: Methodsmentioning

confidence: 99%

Unusual bacterioplankton community structure in ultra‐oligotrophic Crater Lake

Urbach

Vergin

Young

et al. 2001

Limnology & Oceanography

Self Cite

210

243

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The bacterioplankton assemblage in Crater Lake, Oregon (U.S.A.), is different from communities found in other oxygenated lakes, as demonstrated by four small subunit ribosomal ribonucleic acid (SSU rRNA) gene clone libraries and oligonucleotide probe hybridization to RNA from lake water. Populations in the euphotic zone of this deep (589 m), oligotrophic caldera lake are dominated by two phylogenetic clusters of currently uncultivated bacteria: CL120-10, a newly identified cluster in the verrucomicrobiales, and ACK4 actinomycetes, known as a minor constituent of bacterioplankton in other lakes. Deep-water populations at 300 and 500 m are dominated by a different pair of uncultivated taxa: CL500-11, a novel cluster in the green nonsulfur bacteria, and group I marine crenarchaeota. ␤-Proteobacteria, dominant in most other freshwater environments, are relatively rare in Crater Lake (Յ16% of nonchloroplast bacterial rRNA at all depths). Other taxa identified in Crater Lake libraries include a newly identified candidate bacterial division, ABY1, and a newly identified subcluster, CL0-1, within candidate division OP10. Probe analyses confirmed vertical stratification of several microbial groups, similar to patterns observed in open-ocean systems. Additional similarities between Crater Lake and ocean microbial populations include aphotic zone dominance of group I marine crenarchaeota and green nonsulfur bacteria. Comparison of Crater Lake to other lakes studied by rRNA methods suggests that selective factors structuring Crater Lake bacterioplankton populations may include low concentrations of available trace metals and dissolved organic matter, chemistry of infiltrating hydrothermal waters, and irradiation by high levels of ultraviolet light.

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Taxonomic Structure and Productivity of Phytoplankton Assemblages in Crater Lake, Oregon

Cited by 28 publications

References 30 publications

Subsurface maxima of phytoplankton and chlorophyll: Steady‐state solutions from a simple model

Subsurface maxima of phytoplankton and chlorophyll: Steady‐state solutions from a simple model

Representative Freshwater Bacterioplankton Isolated from Crater Lake, Oregon

Unusual bacterioplankton community structure in ultra‐oligotrophic Crater Lake

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