کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5765701 | 1626910 | 2017 | 10 صفحه PDF | دانلود رایگان |
To investigate tropical roles of the newly described Yihiella yeosuensis (ca. 8 μm in cell size), one of the smallest phototrophic dinoflagellates in marine ecosystems, its trophic mode and the types of prey species that Y. yeosuensis can feed upon were explored. Growth and ingestion rates of Y. yeosuensis on its optimal prey, Pyramimonas sp. (Prasinophyceae), as a function of prey concentration were measured. Additionally, growth and ingestion rates of Y. yeosuensis on the other edible prey, Teleaulax sp. (Cryptophyceae), were also determined for a single prey concentration at which both these rates of Y. yeosuensis on Pyramimonas sp. were saturated. Among bacteria and diverse algal prey tested, Y. yeosuensis fed only on small Pyramimonas sp. and Teleaulax sp. (both cell sizes = 5.6 μm). With increasing mean prey concentrations, both specific growth and ingestion rates of Y. yeosuensis increased rapidly before saturating at a mean Pyramimonas concentration of 109 ng C mLâ1 (2725 cells mLâ1). The maximum growth rate (mixotrophic growth) of Y. yeosuensis fed with Pyramimonas sp. at 20 °C under a 14:10-h light-dark cycle of 20 μE mâ2 sâ1 was 1.32 dâ1, whereas the growth rate of Y. yeosuensis without added prey was 0.026 dâ1. The maximum ingestion rate of Y. yeosuensis fed with Pyramimonas sp. was 0.37 ng C predatorâ1 dâ1 (9.3 cells predatorâ1 dâ1). At a Teleaulax concentration of 1130 ng C mLâ1 (66,240 cells mLâ1), growth and ingestion rates of Y. yeosuensis fed with Teleaulax sp. were 1.285 dâ1 and 0.38 ng C predatorâ1 dâ1 (22.4 cells predatorâ1 dâ1), respectively. Thus, Y. yeosuensis rarely grows without mixotrophy, and mixotrophy supports high growth rates in Y. yeosuensis. Y. yeosuensis has the highest maximum mixotrophic growth rate with the exception of Ansanella graniferaamong engulfment feeding mixotrophic dinoflagellates. However, the high swimming speed of Y. yeosuensis (1572 μm sâ1), almost the highest among phototrophic dinoflagellates, may prevent autotrophic growth. This evidence suggests that Y. yeosuensis may be an effective mixotrophic dinoflagellate predator on Pyramimonas and Teleaulax, and occurs abundantly during or after blooms of these two prey species.
Journal: Harmful Algae - Volume 62, February 2017, Pages 94-103