ISSN:
1432-1793
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Vertical distributions of picophytoplankton (ppp) (〈2 μm) were studied by ship-board flow cytometry during two cruises in Western Pacific waters to Palau and to Australia in 1990. Weak red-fluorescing small “ppp”, supposed to be free-living prochlorophytes (Chisholm et al. 1988), were abundant in the area surveyed. These ppp, designated “the prochlorophytes”, were abundant in the surface waters (〉104 cells ml-1) at the northern region (27°03′N; 7°11′N) in November, whereas in December at the southern tropical stations (0°23.54′S; 9°20.30′S; 13°50.6′S), they formed subsurface maximum layers (〉105 cells ml-1) on a nitracline at a depth of 3.5 to 5.4% surface irradiation. Their fluorescence intensity increased with depth below 10% surface irradiation. The prochlorophytes at a depth of 1% surface irradiation had ten times higher fluorescence than those at the surface layer. The total fluorescence intensity of the prochlorophytes accounted for 32 to 63% of the sum of the total fluorescence intensity of all fluorescing phytoplankton detected at subsurface chlorophyll maxima in the tropical area. These results suggest that distribution of the prochlorophytes is greatly affected by nitracline and by light intensity and that their chlorophyll is a major contributor to the subsurface chlorophyll maximum in the pelagic West Pacific Ocean.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00346337
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