Bacteria Abundance, Biomass and Chlorophyll a in Ice Cores

NOTES:
NBP0104: Cores labelled with "DNA" were collected for DNA analysis.

Contributor:
Dr. Christian Fritsen
University and Community College System of Nevada 
Desert Research Institute
Div. of Earth and Ecosystem Sciences
2215 Raggio Parkway
Reno, NV 89512

Office: 775/673-7487

BG 235 - Methods used for chlorophyll a (chla) analysis and bacteria biomass determination

Core Sampling techniques:

Sampling methods for recovery of chlorophyll a and bacteria from sea ice cores follows those described in:
Garrison, D.L. and K.R. Buck(1986), Organism losses during ice melting: a serious bias in sea ice community studies. Polar Biol., 6:237-239.

Recommendations for reporting were used as outlined by:
Horner, R. et al.,(1992), Ecology of Sea Ice Biota. I: Habitat, Terminology and Methodology. Polar Biol. 12:417-427

Analytic Techniques:

Chla (mg m^-3):

• determined fluorometrically (Turner Designs 10AU Fluorometer) following extraction in 90% acetone (Parsons et al., 1984)
• ice core chla corrected to account for chla in filtered sea water (FSW) added to core sections during melting

Bacteria cell abundance (cells m^-3) and biomass (mg C m^-3):

LMG 0106

• preserved (0.5% glutaraldehyde) samples stained with 4',6-diamidino-2-phenylindole (DAPI; 0.1 to 0.3% final concentration), filtered through 0.2 mm black, polycarbonate membrane filters, and mounted onto glass microscope slides on the ship (within 24 hours following collection)
• bacteria enumerated using epifluorescence microscopy and sized using digital images taken with Image Pro Plus
• bacteria biomass determined using cell abundance, cell biovolume (BV; mm³; as determined from mean length and width measurements), and an allometric conversion factor for bacterial carbon per volume specific for DAPI-stained bacteria (cellular carbon = 218 X BV^0.86; Loferer-Kribacher et al., 1998).
• ice core samples corrected for FSW dilution

NBP 0104

• preserved (0.5% glutaraldehyde) samples stained with Sybri Gold (0.01% final concentration), filtered through 0.2 mm Anodisc filters (Whatman), and mounted onto glass microscope slides at home institution (~1-2 months following collection)
• bacteria enumerated using epifluorescence microscopy and sized using digital images taken with Image Pro Plus
• bacteria biomass determined using cell abundance, cell biovolume (BV; mm³), and an allometric conversion factor for bacterial carbon per volume specific for Acridine Orange-stained bacteria (cellular carbon = 89.9 X BV^0.59; Simon and Azam, 1989). Note: an AO-specific carbon per volume conversion factor was used in calculating biomass in Sybri Gold-stained samples because both AO and Sybri Gold stain bacteria cells similarly relative to DAPI (unpublished data).
• ice core samples corrected for FSW dilution

Loferer-Kribacher, M., Klima, J., and R. Psenner. 1998. Determination of bacterial cell dry mass by transmission electron microscopy and densitometric image analysis. Applied and Environmental Microbiology. 64:688-694.

Parsons,T.R., Maita, Y., and C.M. Lalli. 1984. A manual of chemical and biological methods for seawater analysis. Pergamon Press. Elmsford, New York.

Simon, M., and F. Azam. 1989. Protein content and protein synthesis rates of planktonic marine bacteria. Marine Ecology Progress Series. 51, 201-213.

updated: April 20, 2006