Analysis of phytoplankton of the Australian sector of the Southern Ocean:comparisons of microscopy and size frequency data with interpretations of pigment HPLC data using the 'CHEMTAX' matrix factorisation program

Abstract

A new matrix factorization program 'CHEMTAX was used to ~nterpret high-performance hquid chromatography (HPLC) pigment data from a transect between Prydz Bay Antarct~ca and Australla dunng March 1987 The program calculated the abundance of diatoms dinoflagellates haptophytes resembling Emiliania huxleyl haptophytes resembling P h a e o c j~s t~s antarctlca cyanobacteria prasinophytes, chlorophytes and cryptophytes along the transect The results were compared with those of microscopy and particle size analysis The transect was dominated by small cells particle size analysis showed that particles < 2 pm represented 27 to 44 Oh of the total by number while particles 2 to 20 pm represented 55 to 68% Particles >20 pm never represented more than 3 % by number but constituted 57 to 93 % of the total v o l u n~e Microscop~c analysis showed that small flagellates were the most abundant cells along the transect wlth a 5-fold increase In abundance at 47"s Numbers of dlatoms (most <20 pm in size) Increased markedly south of the Polar Front, correlating with the concentration of silica D~noflagellate numbers were relatively constant along the transect although somewhat higher north of 5 0 " s Those <20 pm in size were most numerous and accounted for most of the latltudinal vanation Interpretation of HPLC pigment data using the CHEM TAX program was consistent with microscopical analysis The computed abundances of diatoms and dinoflagellates correlated more strongly with the numbers of small (<20 pm) dlatoms and d~noflagellates, respectively than with large ones Computed cyanobactenal abundances correlated well wlth microscopical observations except for small errors where cyanobactena were absent probably d u e to m~sallocation of zeaxanthln from chlorophvtes and praslnophytes The program was able to distinguish 2 populations of haptophytes along the transect representing Phdeocystis antarctlca and coccol~thophonds even though their pigment compositions were qualitatively (though not quantitatively) Identical It also indicated the separate distributions of chlorophytes and prasinoxarithin-containing praslnophytes, and showed the presence of cryptophytes where none were observed by microscopy

Phytoplankton composition and selective feeding of the pearl oyster Pinctada margaritifera in the Takapoto lagoon (Tuamotu Archipelago, French Polynesia):in situ study using optical microscopy and HPLC pigment analysis

“…An earlier method by Gieskes et al (1988) used a multiple regression analysis to infer the values of the pigment ratios from the measured dataset. A new program for estimating class abundances from chemical markers, so-called CHEMTAX, was developed by Mackey et al (1996) and applied by Wright et al (1996) and Meyer-Harms et al (1999). But this method was not applicable to our dataset because it requires a previous knowledge of the pigment ratios of the local populations.…”

Distribution of planktonic biogenic carbonate organisms in the Southern Ocean south of Australia: a baseline for ocean acidification impact assessment

“…It appears likely that our single-depth sampling can be considered as representative of upper water column phytoplankton concentrations because pigment samples and profiles of beam attenuation and nighttime fluorescence from some of these voyages as well as previous work show that biomass is generally well mixed in the upper water column and that when subsurface chlorophyll maxima are present they primarily reflect increased chlorophyll levels rather than increased phytoplankton abundances (Bowie et al, 2011a, b;Parslow et al, 2001;Rintoul and Trull, 2001;Shadwick et al, 2015;Trull et al, 2001b;Wright et al, 1996;Wright and van den Enden, 2000). This perspective is also consistent with the limited information on the depth distributions of coccolithophores in the Southern Ocean, which generally exhibit relatively uniform and maximal values (especially for the most abundant species, Emiliania huxleyi) within the surface mixed layer (Findlay and Giraudeau, 2000;Holligan et al, 2010;Mohan et al, 2008;Takahashi and Okada, 2000).…”

Iron limitation across chlorophyll gradients in the southern Drake Passage: Phytoplankton responses to iron addition and photosynthetic indicators of iron stress

“…The CHEMTAX program was used to estimate the contribution of different phytoplankton taxa to total Chl a . Taxa known to be present in Antarctic waters (diatoms, haptophytes, dinoflagellates, cryptophytes, prasinophytes, and chlorophytes) were included in the analysis using initial pigment ratios for each taxa determined for Antarctic waters by Wright et al (1996).…”