Bacterivory in algae: A survival strategy during nutrient limitation

Abstract

Bacterivory in obligate phototrophic algal flagellates may be an important strategy for acquiring nutrients during periods of inorganic nutrient limitation.Several marine algal flagellates were shown to increase bactivory when phosphate was limited. Grazing on bacteria by algal flagellates was found during blooms of Prymnesium parvum in Sandsljorden, western Norway, in 1989 and Chrysochromulina polylepis on the south and west coast of Norway in 1988. Dissolved phosphate was not detectable in these situations. Algal flagellates may graze bacteria to obtain phosphate, which may permit these algal flagellates to develop blooms when phosphate becomes limited.

Mixotrophic haptophytes are key bacterial grazers in oligotrophic coastal waters

“…When looking at the same relationship, but by groups, we obtained the same good correlation between phosphorus concentration and CSGR for the cryptophytes, but not for the haptophytes. Experiments with cultures of Chrysochromulina polylepis (Nygaard and Tobiesen, 1993;Stibor and Sommer, 2003), Prymnesium patelliferum (Legrand et al, 2001) and Prymnesium parvum (Nygaard and Tobiesen, 1993) showed a decline in bacterivory activity when nutrients are plentiful, suggesting that haptophytes would utilize phagotrophy as a means to obtain limiting inorganic nutrients. Nevertheless, this prediction could not be confirmed with our in situ estimations.…”

“…Considering the possibility that chrysophytes could have been missed, and taking into account the high bacterivory rates usually reported for these algae, comparables to those of purely HFs (Bird and Kalff, 1986;Nygaard and Tobiesen, 1993), chrysophytes might be responsible for a significant proportion of the total grazing impact by MFs. For instance, Dinobryon faculiferum was found at one occasion in Blanes Bay, and in spite of their very low abundance, this single species accounted for 11% of the total grazing rate exerted by all mixotrophs (Unrein et al, 2010).…”

“…The mixotrophic mode of nutrition is considered to be particularly beneficial when inorganic nutrients are limiting (Nygaard and Tobiesen, 1993;Rothhaupt, 1996;Flö der et al, 2006). It has been demonstrated that mixotrophic algae, in particular those o5 mm in size, are major grazers of picoplankton in oligotrophic marine systems, being regularly responsible for 450% of the total bacterivory (Unrein et al, 2007;Zubkov and Tarran, 2008;Hartmann et al, 2012).…”

“…Mixotrophy in algae, defined as the combination of phagotrophy and phototrophy in a single cell (sensu Sanders, 1991), is widespread among algal groups containing flagellated species (Bird and Kalff, 1986;Tranvik et al, 1989;Nygaard and Tobiesen, 1993;Stoecker, 1999). The mixotrophic mode of nutrition is considered to be particularly beneficial when inorganic nutrients are limiting (Nygaard and Tobiesen, 1993;Rothhaupt, 1996;Flö der et al, 2006).…”

Ribosomal DNA phylogenies and a morphological revision provide the basis for a revised taxonomy of the Prymnesiales (Haptophyta)

“…All known species are photosynthetic, but mixotrophy appears to be common in some genera (e.g. Chrysochromulina and Prymnesium: Kawachi et al, 1991;Nygaard & Tobiesen, 1993;Jones et al, 1994;Tillmann, 1998), and uptake of dissolved organic carbon may also occur (Pintner & Provasoli, 1968).…”