Feeding by the mixotrophic red-tide dinoflagellate Gonyaulax polygramma: mechanisms, prey species, effects of prey concentration, and grazing impact

Aquatic Microbial Ecology

Yeong Du Yoo Kyeong Ah Seong Jong Hyeok Kim Jae Yeon Park Sanghee Kim Seung Hyeon Lee Jeong Hyun Ha Won Ho Yih¹  Hae Jin Jeong¹ 

关键词: Feeding process;    Harmful algal bloom;    Ingestion;    Marine;    Protist;    Red tide;   

DOI  :  10.3354/ame038249

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: The red-tide dinoflagellate Gonyaulax polygramma (GenBank accession number = AJ833631), previously known as an exclusively autotrophic dinoflagellate, has been found to be a mixotrophic species. We investigated feeding mechanisms, typesof prey species, and the effects of prey concentration on the growth and ingestion rates of G. polygramma when feeding on an unidentified cryptophyte species (equivalent spherical diameter, ESD = 5.6 µm). We also calculated grazingcoefficients by combining field data on abundances of G. polygramma and co-occurring cryptophytes with laboratory data on ingestion rates obtained in the present study. Among the phytoplankton prey offered, G. polygramma ingested smallphytoplankton species with ESD ≤ 17 µm, but did not feed on large phytoplankton species with ESD > 22 µm. G. polygramma fed on prey cells by engulfing them through the apical horn, a previously unknown mechanism, as well asthrough the sulcus. The feeding mechanism of G. polygramma on phytoplankton mainly depended on the prey species. Specific growth rates of G. polygramma on a cryptophyte increased with increasing mean prey concentration, with saturationoccurring at a mean prey concentration of approximately 600 ng C ml^–1. The maximum specific (mixotrophic) growth rate of G. polygramma on a cryptophyte was 0.278 d^–1, under a 14:10 h light:dark cycle of 50 µEm^–2 s^–1, while its (phototrophic) growth rate under the same light conditions without added prey was 0.186 d^–1. Its maximum ingestion and clearance rates were 0.18 ng C grazer^–1d^–1 (10.6 cells grazer^–1 d^–1) and 0.18 µl grazer^–1 h^–1, respectively. The grazing coefficients of G. polygramma on cryptophytes were up to 0.479h^–1. The results of the present study suggest that G. polygramma can have a considerable grazing impact on cryptophyte populations.

【 授权许可】

Unknown