Premium
75
The role of feeding in growth and photosynthesis of myrionecta rubra
Author(s) -
Johnson M. D.,
Stoecker D. K.
Publication year - 2003
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.0022-3646.2003.03906001_75.x
Subject(s) - biology , photosynthesis , phototroph , mixotroph , botany , plastid , chlorophyll , chlorophyll a , algae , ciliate , chloroplast , ecology , heterotroph , biochemistry , genetics , bacteria , gene
Myrionecta rubra (=Mesodinium rubrum) is an obligate phototroph that possesses plastids, mitochondria and sometimes nuclei of cryptophyte algae. Plastids and nuclei have been observed to increase in M. rubra when feeding. The current study was conducted in order to better understand the relationship between feeding and photosynthetic physiology in M. rubra . During the experiment, cryptophytes were introduced for 2 consecutive growth periods (14 d) and the cultures were then starved during 4 additional periods. Photosynthesis‐irradiance (PE) response curves were measured twice during each growth period (days 7 and 14), and the parameters alpha and Pmax were measured and normalized to cell and chlorophyll (chl) concentrations. In both treatments, growth rate and nuclei/cell increased significantly when fed (p<0.05), and then declined over time. Cell volume increased substantially in the HL treatment when in the presence of prey (p<0.05), but otherwise varied little. In both treatments, chl/cell and Pmax(cell) increased after feeding and then declined after several weeks in the absence of prey. Absolute changes in these parameters were greater in the LL treatment. In both treatments Pmax(chl) increased over the study. As observed previously, M. rubra appears to possess a limited capacity for producing pigments. While these results illustrate some dependency of photosynthesis and growth in M. rubra upon ingestion of cryptophyte prey, they also display that the ciliate can use and sustain plastids like a phototroph.