Ref ID : 4992
Hae Jin Jeong, Yeong Du Yoo, Jae Seong Kim, Nam Seon Kang, Tae Hoon Kim, and Jong Hyeok Kim; Feeding by the marine planktonic ciliate Strombidinopsis jeokjo on common heterotrophic dinoflagellates. Aquatic Microbial Ecology 36:181-187, 2004
Reprint : In File
Notes : To investigate the interactions between the ciliate Strombidinopsis jeokjo and the heterotrophic dinoflagellates Gyrodinium dominans and Oxyrrhis marina, we measured the growth and ingestion rates of S. jeokjo (mean length and width of fixed specimens = 149 x 70 um, n = 30) when feeding on each of the heterotrophic dinoflagellates, and calculated grazing coefficients by combining field data on abundances of large Strombidinopsis spp. (> 100 um in length) and co-occurring heterotrophic dinoflagellates with laboratory data on ingestion rates obtained in the present study. The specific growth rates of S. jeokjo when feeding on G. dominans and O. marina increased rapidly with increasing prey concentration (ca. < 300 ngC ml-1), but were saturated or slightly increasing at higher concentrations. The maximum specific growth rate of S. jeokjo feeding on G. dominans (0.54 d-1) was similar to that when fed on O. marina (0.59 d-1). Threshold prey concentrations (where net growth = 0) were 79 ngC ml-1 for G. dominans and 36 ngC ml-1 for O. marina. The maximum ingestion and clearance rates of S. jeokjo feeding on G. dominans (108 ngC grazer-1 d-1 and 14.5 ul grazer-1 h-1, respectively) were comparable to those when fed on O. marina (87 ngC grazer-1 d-1 and 13.4 ul grazer-1 h-1, respectively). Calculated grazing coefficients for large Strombidinopsis spp. feeding on G. dominans and O. marina were 0.01 to 0.39 h-1 (i.e. 1 to 33% of G. dominans populations were removed by Strombidinopsis spp. populations in 1 h) and 0.002 to 0.004 h-1 (i.e. 0.2 to 0.4% of O. marina populations were removed), respectively. The results of the present study suggest that Strombidinopsis spp. can sometimes have a considerable grazing impact on populations of G. dominans and O. marina.