On the Relationship between a Novel Prorocentrum sp. and Colonial Phaeocystis antarctica under Iron and Vitamin B 12 Limitation: Ecological Implications for Antarctic Waters

• Published in: Applied Sciences
• Main Authors: Francesco Bolinesi, Maria Saggiomo, Serena Aceto, Angelina Cordone, Emanuela Serino, Maria Carmen Valoroso, Olga Mangoni
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2020
• Subjects: Ross Sea; phytoplankton diversity; photosynthetic efficiency; climate change; Technology; T; Engineering (General). Civil engineering (General); TA1-2040; Biology (General); QH301-705.5; Physics; QC1-999; Chemistry; QD1-999; Antarctic; The Antarctic; Austral; Antarc*; Antarctica
• Online Access: https://doi.org/10.3390/app10196965; https://doaj.org/article/0a3ae23cf7a24e609f440c9dfa1b32db

We collected live mixed natural samples from the northeastern Ross Sea during the austral summer of 2017 and isolated a novel Prorocentrum sp. (Dinophyceae) associated with mucilaginous Phaeocystis antarctica (Coccolithophyceae) colonies. The haptophyte P. antarctica is a key species of the phytoplankton community in the Ross Sea, where blooms are subjected to iron limitation and/or co-limitation with other micronutrients (e.g., vitamin B 12 ) during the summer. We first performed preliminary genetic analyses to determine the specific identity of the novel Prorocentrum sp., which indicated that it represented a previously undescribed species. The formal description of this new species is in process. To further assess its relationship with P. antarctica , we obtained their monospecific and mixed cultures and evaluated their responses to different irradiance levels and iron and vitamin B 12 limitation. Our results indicated differential susceptibility of the two species to iron limitation and differential photosynthetic plasticity under high irradiance. Iron limitation reduced colony formation in P. antarctica and decreased the chlorophyll-a content in Prorocentrum sp., whereas B 12 limitation did not affect growth or photosynthetic efficiency in either species. In addition, P. antarctica could photosynthesize efficiently under different irradiance levels, due to its ability to modulate the light adsorption cross-section of PSII, whereas Prorocentrum sp. exhibited lower photosynthetic plasticity and an inability to modulate both the maximum photochemical efficiency and effective adsorption cross-section of PSII under high irradiance. The trophic interaction between Prorocentrum sp. and P. antarctica could present ecological implications for the food webs and biogeochemical cycles of the Antarctic ecosystem. Considering the predicted climate-driven shifts in global ocean surface light regimes and changes in iron or vitamin B 12 transfer, which are most likely to impact changes in the phytoplankton community ...