Diversity and community structure of eukaryotic phototrophs in the Bering and Chukchi seas

Thesis (M.S.) University of Alaska Fairbanks, 2020The phytoplankton of the Bering and Chukchi seas support highly productive ecosystems characterized by tight benthic-pelagic coupling. In this study, we focus on the northern Bering and Chukchi seas, considering them as one ecosystem. This community has historically been dominated by diatoms; however, climate change and accompanying warming ocean temperatures may alter primary producer communities. Using metabarcoding, we present the first synoptic, high-throughput molecular phylogenetic investigation of phytoplankton diversity in the Bering and Chukchi seas based on hundreds of samples collected from June to September in 2017. We identify the major and minor taxonomic groups of diatoms and picophytoplankton, relative abundances of genera, exact sequence variants (201 for diatoms and 227 for picophytoplankton), and describe their biogeography. These phylogenetic insights and environmental data are used to characterize preferred temperature ranges, offering insight into which specific phytoplankton (Chaetoceros, Pseudo−nitzschia, Micromonas, Phaeocystis) may be most affected as the region warms. Finally, we investigated the likelihood of using shipboard CTD data alone as predictive variables for which members of phytoplankton communities may be present. We found that the suite of environmental data collected from a shipboard CTD is a poor predictor of community composition, explaining only 12.6% of variability within diatom genera and 14.2% variability within picophytoplankton genera. Clustering these communities by similarity of samples did improve predictability (43.6% for diatoms and 32.5% for picophytoplankton). However, our analyses succeeded in identifying temperature as a key driver for certain taxa found commonly throughout the region, offering a key insight into which common phytoplankton community members may be affected first as the Alaskan Arctic continues to warm.National Oceanic and Atmospheric Administration, National Science Foundation, National Oceanographic Partnership Program, North Pacific Research Board, Cooperative Institute for the Alaska Research, and the Robert and Kathleen Byrd Awar

A global marine particle size distribution dataset obtained with the Underwater Vision Profiler 5

International audienceAbstract. Marine particles of different nature are found throughout the global ocean. The term “marine particles” describes detritus aggregates and fecal pellets as well as bacterioplankton, phytoplankton, zooplankton and nekton. Here, we present a global particle size distribution dataset obtained with several Underwater Vision Profiler 5 (UVP5) camera systems. Overall, within the 64 µm to about 50 mm size range covered by the UVP5, detrital particles are the most abundant component of all marine particles; thus, measurements of the particle size distribution with the UVP5 can yield important information on detrital particle dynamics. During deployment, which is possible down to 6000 m depth, the UVP5 images a volume of about 1 L at a frequency of 6 to 20 Hz. Each image is segmented in real time, and size measurements of particles are automatically stored. All UVP5 units used to generate the dataset presented here were inter-calibrated using a UVP5 high-definition unit as reference. Our consistent particle size distribution dataset contains 8805 vertical profiles collected between 19 June 2008 and 23 November 2020. All major ocean basins, as well as the Mediterranean Sea and the Baltic Sea, were sampled. A total of 19 % of all profiles had a maximum sampling depth shallower than 200 dbar, 38 % sampled at least the upper 1000 dbar depth range and 11 % went down to at least 3000 dbar depth. First analysis of the particle size distribution dataset shows that particle abundance is found to be high at high latitudes and in coastal areas where surface productivity or continental inputs are elevated. The lowest values are found in the deep ocean and in the oceanic gyres. Our dataset should be valuable for more in-depth studies that focus on the analysis of regional, temporal and global patterns of particle size distribution and flux as well as for the development and adjustment of regional and global biogeochemical models. The marine particle size distribution dataset (Kiko et al., 2021) is available at https://doi.org/10.1594/PANGAEA.924375

The global marine particle size distribution dataset obtained with the Underwater Vision Profiler 5 - version 1

Particle size distribution data was collected during multiple cruises globally with several regularly intercalibrated Underwater Vision Profilers, Version 5 (UVP5; Picheral et al 2010). During the respective cruises, the UVP5 was mounted on the CTD-Rosette or as a standalone instrument and deployed in vertical mode. The UVP5 takes pictures of an illuminated watervolume of about 1 Liter every few milliseconds. Imaged items are counted, their size measured and abundance and biovolume of the particles is calculated. For different size bins, this information is summarized in the columns "Particle concentration" and "Particle biovolume". For further details please refer to Kiko et al. (in prep.) "A global marine particle size distribution dataset obtained with the Underwater Vision Profiler 5"