TY - JOUR

T1 - Role of food uptake for photosynthesis, growth and survival of the mixotrophic dinoflagellate Dinophysis acuminata

AU - Riisgaard, Karen

AU - Hansen, Per Juel

N1 - KEY WORDS: Dinophysis acuminata · Dinoflagellate · Mixotrophy · Photosynthesis · Growth · Survival · Mesodinium rubrum

PY - 2009/4/17

Y1 - 2009/4/17

N2 - Dinophysis acuminata is a mixotrophic dinoflagellate frequently causing diarrhetic shellfish poisoning. D. acuminata was isolated from Danish coastal waters and cultivated using the mixotrophic ciliate Mesodinium rubrum as prey. The roles of food uptake and photosynthesis for the growth and survival of D. acuminata were studied. The observed maximum growth rate was ca. 0.45 d-1 at an irradiance of 100 µmol photons m-2 s-1 when supplied with well-fed M. rubrum at concentrations >1000 M. rubrum ml-1. The corresponding ingestion rate per D. acuminata was about 9 M. rubrum d-1, or 3200 pg C d-1. Apart from the importance of prey concentration, data revealed that ingestion and growth of D. acuminata are, to a certain degree, dependent on the growth rate of its ciliate prey. Photosynthesis was studied in a culture of D. acuminata, initially grown at prey saturation (>1000 M. rubrum cells ml-1) and subsequently allowed to deplete the prey. When the ciliate prey was added, the photosynthetic rate of D. acuminata increased from about 7 to 38 pg C cell-1 h-1 within the first 2 d. When subsequently subjected to starvation, the photosynthetic activity rapidly decreased to a pre-feeding level, and, without a minimum food uptake, D. acuminata was not able to maintain photosynthetic growth. At high prey concentrations, 70 to 90% of the gross C uptake can be explained by food uptake. However, at low prey concentrations, only 0 to 55% of the gross C uptake is likely to be derived from food uptake. The data indicate that in natural environments, D. acuminata may often be food limited, and, in this situation, photosynthesis may not only be a supplement to the basic nutrition, but rather the primary C source.

AB - Dinophysis acuminata is a mixotrophic dinoflagellate frequently causing diarrhetic shellfish poisoning. D. acuminata was isolated from Danish coastal waters and cultivated using the mixotrophic ciliate Mesodinium rubrum as prey. The roles of food uptake and photosynthesis for the growth and survival of D. acuminata were studied. The observed maximum growth rate was ca. 0.45 d-1 at an irradiance of 100 µmol photons m-2 s-1 when supplied with well-fed M. rubrum at concentrations >1000 M. rubrum ml-1. The corresponding ingestion rate per D. acuminata was about 9 M. rubrum d-1, or 3200 pg C d-1. Apart from the importance of prey concentration, data revealed that ingestion and growth of D. acuminata are, to a certain degree, dependent on the growth rate of its ciliate prey. Photosynthesis was studied in a culture of D. acuminata, initially grown at prey saturation (>1000 M. rubrum cells ml-1) and subsequently allowed to deplete the prey. When the ciliate prey was added, the photosynthetic rate of D. acuminata increased from about 7 to 38 pg C cell-1 h-1 within the first 2 d. When subsequently subjected to starvation, the photosynthetic activity rapidly decreased to a pre-feeding level, and, without a minimum food uptake, D. acuminata was not able to maintain photosynthetic growth. At high prey concentrations, 70 to 90% of the gross C uptake can be explained by food uptake. However, at low prey concentrations, only 0 to 55% of the gross C uptake is likely to be derived from food uptake. The data indicate that in natural environments, D. acuminata may often be food limited, and, in this situation, photosynthesis may not only be a supplement to the basic nutrition, but rather the primary C source.

U2 - 10.3354/meps07953

DO - 10.3354/meps07953

M3 - Journal article

VL - 381

SP - 51

EP - 62

JO - Marine Ecology - Progress Series

JF - Marine Ecology - Progress Series

SN - 0171-8630

ER -