The Canadian province of Alberta contains substantial oilsands reservoirs, consisting of bitumen, clay and sand. Extracting oil involves separating bitumen from inorganic particles using hot water and chemical diluents, resulting in liquid tailings waste with ecotoxicologically significant compounds. Ongoing efforts aim to reclaim tailings-affected areas, with protist colonisation serving as one assessment method of reclamation progress. Oilsands-associated protist communities have mainly been evaluated using amplicon sequencing of the 18S rRNA V4 region; however, this barcode may overlook important protist groups. This study examined how community assessment methods between the V4 and V9 regions differ in representing protist diversity across four oilsands-associated environments. The V9 barcode identified more operational taxonomical units (OTUs) for Discoba, Metamonada and Amoebozoa compared with the V4. A comparative shotgun metagenomics approach revealed few eukaryotic contigs but did recover a complete Paramicrosporidia mitochondrial genome, only the second publicly available from microsporidians. Both V4 and V9 markers were informative for assessing community diversity in oilsands-associated environments and are most effective when combined for a comprehensive taxonomic estimate, particularly in anoxic environments.

• Keywords
• amplicon, diversity, metagenome, mitochondrial genome, oilsands, protist,
• MeSH
• Biodiversity MeSH
• Eukaryota * genetics   classification   isolation & purification   MeSH
• Phylogeny MeSH
• Metagenomics * methods   MeSH
• RNA, Ribosomal, 18S genetics   MeSH
• Oil and Gas Fields * parasitology   MeSH
• Sequence Analysis, DNA MeSH
• DNA Barcoding, Taxonomic MeSH
• Publication type
• Journal Article MeSH
• Comparative Study MeSH
• Geographicals
• Alberta MeSH
• Names of Substances
• RNA, Ribosomal, 18S MeSH

Polar oceans belong to the most productive and rapidly changing environments, yet our understanding of this fragile ecosystem remains limited. Here we present an analysis of a unique set of DNA metabarcoding samples from the western Weddell Sea sampled throughout the whole water column and across five water masses with different characteristics and different origin. We focus on factors affecting the distribution of planktonic pico-nano eukaryotes and observe an ecological succession of eukaryotic communities as the water masses move away from the surface and as oxygen becomes depleted with time. At the beginning of this succession, in the photic zone, algae, bacteriovores, and predators of small eukaryotes dominate the community, while another community develops as the water sinks deeper, mostly composed of parasitoids (syndinians), mesoplankton predators (radiolarians), and diplonemids. The strongly correlated distribution of syndinians and diplonemids along the depth and oxygen gradients suggests their close ecological link and moves us closer to understanding the biological role of the latter group in the ocean ecosystem.

• MeSH
• Ecosystem * MeSH
• Eukaryota * MeSH
• Oxygen MeSH
• Oceans and Seas MeSH
• Water MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Oceans and Seas MeSH
• Names of Substances
• Oxygen MeSH
• Water MeSH

Euglenozoa is a species-rich group of protists, which have extremely diverse lifestyles and a range of features that distinguish them from other eukaryotes. They are composed of free-living and parasitic kinetoplastids, mostly free-living diplonemids, heterotrophic and photosynthetic euglenids, as well as deep-sea symbiontids. Although they form a well-supported monophyletic group, these morphologically rather distinct groups are almost never treated together in a comparative manner, as attempted here. We present an updated taxonomy, complemented by photos of representative species, with notes on diversity, distribution and biology of euglenozoans. For kinetoplastids, we propose a significantly modified taxonomy that reflects the latest findings. Finally, we summarize what is known about viruses infecting euglenozoans, as well as their relationships with ecto- and endosymbiotic bacteria.

• Keywords
• Diplonemida, Euglenida, Kinetoplastida, microbial eukaryotes, phylogeny, systematics,
• MeSH
• Ecosystem MeSH
• Euglenozoa classification   genetics   physiology   virology   MeSH
• Phylogeny MeSH
• Mimiviridae pathogenicity   MeSH
• Symbiosis MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH