Bioavailable iron in oligotrophic Lake Superior assessed using biological reporters

McKay, R. Michael L.; Porta, David; Bullerjahn, George S.; Al-Rshaidat, Mamoon M. D.; Klimowicz, Jeffrey A.; Sterner, Robert W.; Smutka, Tanya M.; Brown, E. T.; Sherrell, Robert M.

doi:10.1093/plankt/fbi070

Cited by 25 publications

(25 citation statements)

References 56 publications

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“…The work presented here summarizes our efforts to determine the biodiversity of the Lake Superior APP that comprises up to 50% of total Chl in the open lake (9,24). The vast majority of Lake Superior cyanobacterial 16S rRNA gene clones obtained in the present study belonged to the robust picoplankton clade sensu Urbach et al (36), which consists of both marine and freshwater picocyanobacteria.…”

Section: Discussionmentioning

confidence: 64%

“…Instead, the picocyanobacterial community at PD appeared more diverse than the pelagic community and consisted of members of the C. gracile cluster, group B (subalpine cluster I), the Lake Biwa cluster sensu Ernst et al (7), group H, as well as two new minor PD-specific clusters, PDI and PDII. Pelagic Lake Superior is an extremely oligotrophic system in which the combination of chemical and physical factors may create a unique environment in which phytoplankton are severely limited by low concentrations of phosphorus and iron, as well as constrained by light and temperature regimes unfavorable for photosynthesis (17,24,26,34). The evident differences in the APP community between the pelagic western arm of Lake Superior and the nearshore station PD located in a region subject to high coastal influence allow us to suggest the existence of novel ecotypes of Synechococcus spp.…”

Section: Discussionmentioning

confidence: 99%

“…PE-rich picocyanobacteria contribute significantly to total phytoplankton biomass and primary production in Laurentian Great Lakes, including Lake Superior (3,9,10). Indeed, recent surveys of pelagic Lake Superior revealed that APP contribute up to 50% of total Chl (9,24). Despite their importance, the biodiversity of the Great Lakes APP is poorly understood.…”

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confidence: 99%

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Lake Superior Supports Novel Clusters of Cyanobacterial Picoplankton

Ivanikova

Popels

McKay

et al. 2007

Appl Environ Microbiol

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Very little is known about the biodiversity of freshwater autotrophic picoplankton (APP) in the Laurentian Great Lakes, a system comprising 20% of the world's lacustrine freshwater. In this study, the genetic diversity of Lake Superior APP was examined by analyzing 16S rRNA gene and cpcBA PCR amplicons from water samples. By neighbor joining, the majority of 16S rRNA gene sequences clustered within the "picocyanobacterial clade" consisting of freshwater and marine Synechococcus and Prochlorococcus. Two new groups of Synechococcus spp., the pelagic Lake Superior clusters I and II, do not group with any of the known freshwater picocyanobacterial clusters and were the most abundant species (50 to 90% of the sequences) in samples collected from offshore Lake Superior stations. Conversely, at station Portage Deep (PD), located in a nearshore urbanized area, only 4% of the sequences belonged to these clusters and the remaining clones reflected the freshwater Synechococcus diversity described previously at sites throughout the world. Supporting the 16S rRNA gene data, the cpcBA library from nearshore station PD revealed a cosmopolitan diversity, whereas the majority of the cpcBA sequences (97.6%) from pelagic station CD1 fell within a unique Lake Superior cluster. Thus far, these picocyanobacteria have not been cultured, although their phylogenetic assignment suggests that they are phycoerythrin (PE) rich, consistent with the observation that PE-rich APP dominate Lake Superior picoplankton. Lastly, flow cytometry revealed that the summertime APP can exceed 10 5 cells ml ؊1 and suggests that the APP shifts from a community of PE and phycocyanin-rich picocyanobacteria and picoeukaryotes in winter to a PE-rich community in summer.

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Section: Discussionmentioning

confidence: 64%

Section: Discussionmentioning

confidence: 99%

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Lake Superior Supports Novel Clusters of Cyanobacterial Picoplankton

Ivanikova

Popels

McKay

et al. 2007

Appl Environ Microbiol

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“…Such bioreporters are being developed for phytoplankton (e.g. McKay et al, 2005) and could prove useful for the study of zooplankton nutrition. Elemental bioreporters would allow for immediate and relatively rapid assessment of the in situ nutritional state of an animal.…”

Section: Resultsmentioning

confidence: 99%

Responses of alkaline phosphatase activity to phosphorus stress in Daphnia magna

McCarthy

Rafferty

Frost

2010

Journal of Experimental Biology

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SUMMARYWe examined how alkaline phosphatase (AP) activity within the bodies and in the materials released by the crustacean Daphnia magna responds to variable algal food phosphorus (P)-content. We found that Daphnia eating P-poor food (C:P~700) had significantly higher AP activity in their bodies on a mass-specific basis compared with individuals eating P-rich food (C:P~100). This dietary P effect on AP activity was not altered by Daphnia starvation but was partially related to differences in the P concentration of animal body homogenates. By contrast, poor P-nutrition of Daphnia lowered AP activity in released materials compared with that measured from their P-sufficient conspecifics. Moreover, AP activity in Daphnia release was lowest in animals consuming P-poor food for longer time periods. Our results support the hypothesis that AP activity increases inside P-limited Daphnia as a mechanism to increase P-acquisition and retention from ingested algae in these nutritionally stressed animals. The lower level of AP activity present in the water of P-deprived animals could reflect a change from largely free to membrane-bound AP isotypes in the digestive tracts of P-starved animals or a decrease in the shedding of membrane-anchored AP from their intestinal lining. These results supplement accumulating evidence that P-poor algal food reduces the dietary mineral P available to Daphnia. In addition, animal body AP activity measurements, with some refinement, may prove useful as an in situ indicator of P-stress in aquatic consumers.

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“…Efforts to address this void have included the development of bioreporter constructs to assay Fe bioavailability. We previously described a freshwater cyanobacterial Fe bioreporter capable of yielding bioluminescence in response to Fe deficiency (11,14,25) and have demonstrated its applicability to measure Fe availability in the Laurentian Great Lakes (20,26). Here we describe the development of a bioreporter suitable for studies of Fe availability in marine systems.…”

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confidence: 99%

Luminescent Whole-Cell Cyanobacterial Bioreporter for Measuring Fe Availability in Diverse Marine Environments

Boyanapalli

Bullerjahn

Pohl

et al. 2007

Appl Environ Microbiol

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A Synechococcus sp. strain PCC 7002 Fe bioreporter was constructed containing the isiAB promoter fused to the Vibrio harveyi luxAB genes. Bioreporter luminescence was characterized with respect to the free ferric ion concentration in trace metal-buffered synthetic medium. The applicability of the Fe bioreporter to assess Fe availability in the natural environment was tested by using samples collected from the Baltic Sea and from the high-nutrient, low-chlorophyll subarctic Pacific Ocean. Parallel assessment of dissolved Fe and bioreporter response confirmed that direct chemical measurements of dissolved Fe should not be considered alone when assessing Fe availability to phytoplankton.

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Bioavailable iron in oligotrophic Lake Superior assessed using biological reporters

Cited by 25 publications

References 56 publications

Lake Superior Supports Novel Clusters of Cyanobacterial Picoplankton

Lake Superior Supports Novel Clusters of Cyanobacterial Picoplankton

Responses of alkaline phosphatase activity to phosphorus stress in Daphnia magna

Luminescent Whole-Cell Cyanobacterial Bioreporter for Measuring Fe Availability in Diverse Marine Environments

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