Observations on the Diversity and Ecology of Freshwater Nannochloropsis (Eustigmatophyceae), with Descriptions of New Taxa

Fawley, Karen P.; Fawley, Marvin W.

doi:10.1016/j.protis.2007.03.003

Cited by 94 publications

(65 citation statements)

References 23 publications

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“…S1 in the supplemental material). Nannochloropsis-dominated algal blooms have been detected in other aquatic systems during cold-water periods (7,8,18), implying that they are adapted to low temperatures. Second, a cryptophyte species identified as Geminigera cryophila was identified as an active member in the shallow layers (see Fig.…”

Section: Discussionmentioning

confidence: 99%

Diversity and Expression of RubisCO Genes in a Perennially Ice-Covered Antarctic Lake during the Polar Night Transition

Kong

Ream

Priscu

et al. 2012

Appl Environ Microbiol

102

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ABSTRACTThe autotrophic communities in the lakes of the McMurdo Dry Valleys, Antarctica, have generated interest since the early 1960s owing to low light transmission through the permanent ice covers, a strongly bimodal seasonal light cycle, constant cold water temperatures, and geographical isolation. Previous work has shown that autotrophic carbon fixation in these lakes provides an important source of organic matter to this polar desert. Lake Bonney has two lobes separated by a shallow sill and is one of several chemically stratified lakes in the dry valleys that support year-round biological activity. As part of an International Polar Year initiative, we monitored the diversity and abundance of major isoforms of RubisCO in Lake Bonney by using a combined sequencing and quantitative PCR approach during the transition from summer to polar winter. Form ID RubisCO genes related to a stramenopile, a haptophyte, and a cryptophyte were identified, while primers specific for form IA/B RubisCO detected a diverse autotrophic community of chlorophytes, cyanobacteria, and chemoautotrophic proteobacteria. Form ID RubisCO dominated phytoplankton communities in both lobes of the lake and closely matched depth profiles for photosynthesis and chlorophyll. Our results indicate a coupling between light availability, photosynthesis, andrbcLmRNA levels in deep phytoplankton populations. Regulatory control ofrbcLin phytoplankton living in nutrient-deprived shallow depths does not appear to be solely light dependent. The distinct water chemistries of the east and west lobes have resulted in depth- and lobe-dependent variability in RubisCO diversity, which plays a role in transcriptional activity of the key gene responsible for carbon fixation.

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Section: Discussionmentioning

confidence: 99%

Diversity and Expression of RubisCO Genes in a Perennially Ice-Covered Antarctic Lake during the Polar Night Transition

Kong

Ream

Priscu

et al. 2012

Appl Environ Microbiol

102

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“…Four ribotypes (groups of strains identified through phylogenetic analysis of the LSU rRNA gene) of Cochlodinium polykrikoides Margalef were clearly identified and reflected geographic origin (Reñé et al, 2013), but the authors chose to number the clades rather than recognize them taxonomically. Cryptic eustigmatophyte taxa were found by Fawley & Fawley (2007), but they chose to recognize the diversity on the varietal level within an already existing species of Nannochloropsis. In Cyanobacteria, the presence of cryptic species has been reported in Microcoleus steenstrupii Boye-Petersen (Boyer et al, 2002), Phormidium retzii (Ag.)…”

Section: Taxonomic Recognition Of Cryptic Speciesmentioning

confidence: 99%

Seven new species ofOculatella(Pseudanabaenales, Cyanobacteria): taxonomically recognizing cryptic diversification

Osorio‐Santos¹,

Pietrasiak²,

Bohunická³

et al. 2014

European Journal of Phycology

150

165

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A total of 27 strains of Oculatella were isolated, characterized and sequenced, and analysed phylogenetically with an additional environmental clone from the Atacama Desert and 10 strains isolated and sequenced by others. The strains were clearly separated based upon phylogenetic analyses conducted with a concatenated alignment of the 16S rRNA and 16S-23S ITS region of the ribosomal operons in the genus Oculatella. Differences in secondary structure of the conserved domains of the ITS region, as well as comparative analysis of P-distance among ITS regions, served to separate the strains into distinct taxonomic units. Seven new species of Oculatella were described, including four from arid to semi-arid soils (O. atacamensis, O. mojaviensis, O. coburnii, O. neakameniensis) and three from more mesic habitats, including a temperate lake (O. hafneriensis), a desert waterfall (O. cataractarum) and a Hawaiian sea cave (O. kauaiensis). The soil forms show statistically significant morphological differences, but the ranges overlap to a degree that they are not diagnosable by morphology, and these four cryptic species are characterized here using molecular characters. The more mesic species, including the type species from Mediterranean hypogea, O. subterranea, are all morphologically distinct from each other and from all four soil taxa. This report is the first to use solely molecular criteria to distinguish cryptic species of cyanobacteria.

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“…The most abundant stramenopile phylotype was related to Nannochloropsis species (Supplementary Figure SI 2C). Nannochloropsis-dominated algal blooms have been detected in other aquatic systems during cold-water periods (Krienitz et al, 2000;Fietz et al, 2005;Fawley and Fawley, 2007), suggesting that they are well adapted to low temperatures. Haptophytes were more abundant in ELB (10%) than Figure 1 Relative contribution of major eukaryotic groups from Eukarya 18S rRNA partial sequences in the photic zone of Lake Bonney.…”

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confidence: 99%

Protist diversity in a permanently ice-covered Antarctic Lake during the polar night transition

et al. 2011

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The McMurdo Dry Valleys of Antarctica harbor numerous permanently ice-covered lakes, which provide a year-round oasis for microbial life. Microbial eukaryotes in these lakes occupy a variety of trophic levels within the simple aquatic food web ranging from primary producers to tertiary predators. Here, we report the first molecular study to describe the vertical distribution of the eukaryotic community residing in the photic zone of the east lobe (ELB) and west lobe (WLB) of the chemically stratified Lake Bonney. The 18S ribosomal RNA (rRNA) libraries revealed vertically stratified populations dominated by photosynthetic protists, with a cryptophyte dominating shallow populations (ELB-6 m; WLB-10 m), a haptophyte occupying mid-depths (both lobes 13 m) and chlorophytes residing in the deepest layers (ELB-18 and 20 m; WLB-15 and 20 m) of the photic zone. A previously undetected stramenopile occurred throughout the water column of both lobes. Temporal variation in the eukaryotic populations was examined during the transition from Antarctic summer (24-h sunlight) to polar night (complete dark). Protist diversity was similar between the two lobes of Lake Bonney due to exchange between the photic zones of the two basins via a narrow bedrock sill. However, vertical and temporal variation in protist distribution occurred, indicating the influence of the unique water chemistry on the biology of the two dry valley watersheds.

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Observations on the Diversity and Ecology of Freshwater Nannochloropsis (Eustigmatophyceae), with Descriptions of New Taxa

Cited by 94 publications

References 23 publications

Diversity and Expression of RubisCO Genes in a Perennially Ice-Covered Antarctic Lake during the Polar Night Transition

Diversity and Expression of RubisCO Genes in a Perennially Ice-Covered Antarctic Lake during the Polar Night Transition

Seven new species ofOculatella(Pseudanabaenales, Cyanobacteria): taxonomically recognizing cryptic diversification

Protist diversity in a permanently ice-covered Antarctic Lake during the polar night transition

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