TAXONOMIC STUDY OF BIGELOWIELLA LONGIFILA SP. NOV. (CHLORARACHNIOPHYTA) AND A TIME‐LAPSE VIDEO OBSERVATION OF THE UNIQUE MIGRATION OF AMOEBOID CELLS1

A new species of a chlorarachniophyte alga, Bigelowiella longifila sp. nov., is described. It is classified as a member of Bigelowiella as flagellate cells constitute the main stage of the life cycle. However, this alga is different from the only described species of the genus, B. natans Moestrup, in having a unique amoeboid stage in the life cycle. We observed an interesting behavior of amoeboid daughter cells after cell division: One of the two daughter cells inherits the long filopodium of the parental cell, and it subsequently transports its cell contents through the filopodium to develop at its opposite end. The other daughter cell forms a new filopodium. This unequal behavior of daughter cells may have evolved before the chlorarachniophytes and some colorless cercozoans diverged.     

Rubble fields shape planktonic protist communities in Indonesia at a local scale

The Coral Triangle encompasses nearly 30% of the world's coral reefs and is widely considered the epicenter of marine biodiversity. Destructive fishing practices and natural disturbances common to this region damage reefs leaving behind fields of coral rubble. While the impacts of disturbances in these ecosystems are well documented on metazoans, we have a poor understanding of their impact on microbial communities at the base of the food web. We use metabarcoding to characterize protist community composition in sites of varying fisheries management schemes and benthic profiles across the island of Lombok, Indonesia. Our study shows that rubble coverage and net primary productivity are the strongest explainers of variation in protist communities across Lombok. More specifically, rubble fields are characterized by increases in small heterotrophic protists, including ciliates and cercozoans. In addition to shifts in heterotrophic protist communities, we also observed increases in diatom relative abundance in rubble fields, which corresponded to sites with higher net primary productivity. These results are the first to characterize protist communities in tropical marine rubble fields and provide insight on environmental factors potentially driving these shifts on a local scale.