Diversity and abundance of haptophytes in the East China Sea

Abstract

Haptophytes (Prymnesiophytes) are important members of eukaryotic phytoplankton and therefore influence carbon and sulfur cycles in the marine ecosystem. The objective of this study was to investigate the distribution and taxonomic composition of haptophytes in the East China Sea (ECS). Our sampling area covered the ECS continental shelf in the spring and summer of 2009. An abundance of haptophytes was revealed by fluorescent in situ hybridization with an 18S rRNA-specific probe. A haptophyte blooming event reaching 2.2 × 10 4 cells ml −1 was observed in the Yellow Sea Mixing Water in spring. Phylogenetic analysis of the 18S rRNA gene revealed that the majority of this bloom was composed of Phaeocystis sequences that affiliated with P. jahnii and P. cordata. In contrast, in summer the assemblage composition of haptophytes was dominated by Chrysochromulina, with a maximum abundance of 3.1 × 10 3 cells ml −1 occurring near the edge of the Changjiang Diluted Water. We also noted a relationship between larger size haptophytes and water eutrophication. The contribution of haptophytes to total nanoflagellate abundance at the ECS surface was 32% in spring and 12% in summer.KEY WORDS: Haptophyte · Phaeocystis · 18S rRNA gene Resale or republication not permitted without written consent of the publisher

Spatiotemporal variations of phytoplankton in the East China Sea and the Yellow Sea revealed by lipid biomarkers

“…Similarly, we observed significant positive correlations between the springtime C 37 alkenones and temperature (Table ). The temperature‐growth curve showed that the maximum specific growth rate occurred at around 17°C in Phaeocystis [ Schoemann et al ., ], with a similar temperature (15.7°C) for the peak haptophyte abundance in the ECS in spring [ Lin et al ., ]. Both temperatures above are within the range of that (14 to 19°C) at stations where C 37 alkenones detected in our study.…”

“…As mentioned above, this might be due to the absence of alkenones in the dominant haptophytes ( Chrysochromulina sp.) in the ECS [ Lin et al ., ; Marlowe et al ., ]. The correlations between C 37 alkenones and hydrological parameters (and nutrients) differ from that for brassicasterol (and dinosterol), especially in summer when C 37 alkenones correlated negatively with nutrients, while brassicasterol and dinosterol showed positive correlations with nutrients (Table ).…”

“…oceanica (maximum abundance: 23.28 cells mL −1 ; Area IV) and E . huxleyi (maximum abundance: 7.35 cells mL −1 ; Area IV) [ Lin et al ., ; Sun et al ., ]. In contrast, we observed low summertime alkenones in Areas III and IV, which might be explained by the absence of alkenones in the most abundant haptophytes, Chrysochromulina sp., in the ECS.…”

“…The temperature dependence of growth physiology is considered to be most important in controlling the distribution of haptophytes in the oceans [ Lin et al ., ; Schoemann et al ., ]. Similarly, we observed significant positive correlations between the springtime C 37 alkenones and temperature (Table ).…”

“…and Phaeocystis sp. [Lin et al, 2014;Marlowe et al, 1984;Volkman, 2000]. All four haptophytes above can produce the pigment marker 19'-hexanoyloxyfucoxanthin [Jeffrey et al, 2011].…”