Dataset: mesopelagic_microplankton

  PI:              David Garrison and Marcia Gowing
  dataset:         Mesopelagic microplankton abundance and carbon biomass
  project/cruise:  Arabian Sea/TTN-050 - Process Cruise 5
  ship:            Thomas Thompson
 

Mesopelagic microplankton Methodology: 11 August 2004

Water samples were collected from 250 to 1000 or 1100 m depth. On cruises 
TTN043 and TTN045 aliquots totaling 4-9 liters per depth were taken from 
two 10 liter Niskin bottles. On cruises TTN050 and TTN054, entire contents 
(42-59 liters) of six 10 liter Niskin bottles per depth were used. Organisms 
were then concentrated within ~ 225 ml by the reverse filtration technique 
(Dodson and Thomas 1978) with 20 micrometer pore sized NitexTM mesh. 
Concentrated samples were measured and preserved in glass jars with a solution 
of 20% paraformaldehyde in 5% sodium borate to give a final concentration of 
2% paraformaldehyde. Entire samples were settled in the dark at 4 degrees °C 
in chambers to which a drop of a 1 mg per ml aqueous solution of DAPI 
(Coleman 1980) had been added. Entire chambers were examined at 150X using an 
epifluorescence microscope and a combination of tungsten and UV light. 
Microplankton (predominantly organisms 20-200 micrometers but sometimes larger) 
with a stained nucleus were counted and measured. Biomass was estimated by 
converting cell volumes to carbon using conversion factors for the various 
groups as described by Gowing et al. (2003).
References:

Coleman, A.W. 1980. Enhances staining of bacteria in natural environments by

fluorochrome staining of DNA. Limnol. Oceanogr. 25:948-951.
Dodson, A.N., W.H. Thomas. 1978. Reverse filtration. In: Sournia, A. (ed),

Phytoplankton Manual. UNESCO, Paris, pp. 104-122.
Gowing, M.M., D.L. Garrison, K.F. Wishner, C. Gelfman. 2003. Mesopelagic

microplankton of the Arabian Sea. Deep-Sea Res. I. 50:1205-1234.
PI note regarding multi-bottle sampling


 Note: _gt20 in the parameter names indicates organisms predominantly

 20-200 micrometers but sometimes larger in size.