Photosynthesis in Mesodinium rubrum: species-specific measurements and comparison to community rates

Abstract

ABSTRACT. The photosynthetic c h a t e Mesodinium rubrum is a common component of the plankton in estuarine, coastal and offshore areas. Unusually high photosynthetic rates [ 2 10 pghave been measured during vlsible blooms (red-waters) of this species, but llttle data were available on photosynthesis by Mesodmium during more routine conditions. We used single cell techniques to measure chlorophyll content and rates of photosynthesis in Mesodinium (16 to 18 X 21 to 22 pm in size) that were part of mixed-species phytoplankton assemblages in small estuaries and salt ponds. The carbon:chlorophyll a (wt:wt) ratio for Mesodinium ranged from 47 to 78. Light-saturated rates of photosynthesis ranged from 13 to 88 pg C cell-' h-' 11.8 to 8.6 pg C (pg chl a)-' h-']. These speciesspecific assimilation ratios were within the mid-range reported for community measurements made during Mesodinium red-waters and within the range reported for phytoplankton. Ik values for Mesodiniurn were 2-275 pE m-' S-' in all experiments. At saturating irradiance, carbon fixation ranged up to ca 14 % of body C h-' In our incubations, Mesodinium accounted for from < 1 to 2-70 % of the community primary production in surface water samples although at no time during our studies did it cause red-waters.

Seasonal distributions of the photosynthesizing ciliates Laboea strobila and Myrionecta rubra (= Mesodinium rubrum) in an estuary of the Gulf of Maine

“…Stoecker et al 1991), but M. rubra accounted for >70% of the community primary production during one experiment in a small estuary (Stoecker et al 1991). L. strobila and M. rubra together accounted for 1 to 7 % of total photosynthesis (up to >90% of the photosynthesis by microplankton) at several stations in the Gulf of Maine during July .…”

“…For M. rubra variations in size could affect the estimates of their photosynthetic contribution. The rate used in my calculations (85 pg C cell-' h-') was for cells 30 to 50 pm in length, but smaller M, rubra may have a reduced per cell rate at a given light intensity (Stoecker et al 1991). Two distinct size classes of M. rubra have previously been reported to occur either together or in different seasons (Lindholm 1985, Montagnes & Lynn 1989, Bernard & Rassoulzadegan 1994, and 2 size classes of A4.…”

“…Recently, single cell isolation techniques showed that maximum photosynthetic rates (P,,,) for Laboea strobila and Myrionecta rubra were in the range of those for phytoplankton (Stoecker et al 1988(Stoecker et al , 1991.…”

The Importance of Mesodinium rubrum at Post-Spring Bloom Nutrient and Phytoplankton Dynamics in the Vertically Stratified Baltic Sea

“…rubrum is extremely mobile, known to be fastest autotroph in the sea with a swimming velocity that is reported to reach 8.5 mm s −1 (30 m h −1 ; Smayda, 2010) and showing marked phototaxis and vertical migrations (Lindholm, 1985). Some studies already a long time ago demonstrated the very high rate of primary production of this species (e.g., Mackenzie and Gillespie, 1986;Crawford, 1989;Stoecker et al, 1991; review by Johnson, 2011). Increased temperature and water column stability, decreased salinity and depletion of dissolved inorganic nitrogen from the surface layer are known to have positive influence to the occurrence and abundance of M. rubrum (Lindholm and Mörk, 1990;Cloern et al, 1994;Montagnes et al, 2008;Johnson et al, 2013) in different locations worldwide.…”

“…M. rubrum mass occurrences tend to develop in a chemical environment where competing photosynthetic species are a resource (nutrient) limited or are not able to migrate vertically to exploit the pools of dissolved inorganic nutrients below the euphotic layer. Ability to migrate vertically complemented with efficient nutrient uptake has been considered to enable M. rubrum to compete with phytoplankters (Stoecker et al, 1991).…”