Research Progress in Area 1 方向 ( 一 ) 課題進展 73 Abstract Copepods provide a rich organic microenvironment allowing the settlement and proliferation of microorganisms, thus form dynamic microbial hotspots in the oceans. Symbiotic associations in the plankton were previously hypothesized to be especially developed in warm oligotrophic seas, as they have a potential role in enhancing nutrient availability in biologically poor waters. Here, we characterized the associated microbiota of three dominant coastal epipelagic copepods in the ultraoligotrophic Eastern Mediterranean Sea using 16S rRNA amplicon sequencing. Research Activities and Progress • Zooplankton and seawater sampling were carried out seasonally during 2020; • Three epipelagic copepod species, the filter-feeder Temora stylifera, the ambushfeeder Oithona nana, and the mixed-feeder Centropages ponticus, were identified and picked for molecular analysis; • DNA was extracted from copepods and seawater and 16S rRNA gene was amplified and sequenced using NGS. Additionally, copepod COI gene was sequenced for copepod molecular identification. Key Findings • Copepod-associated microbial communities were host specific rather than determined by seasonal environmental changes; • The microbiome diversity of the filter-feeding copepod with a tendency to herbivory, Temora stylifera, was lowand relatively stable throughout the year. The ambush-feeding omnivore, Oithona nana, and the mixed-feeding omnivore, Centropages ponticus, harboured more diverse microbiomes, dominated by transient taxa; • Filter-feeding strategy and narrow food spectrum of T. stylifera might limit potential interactions to certain microbial taxa, while the ambush andmixed feeding strategies combined with omnivory of O. nana and C. ponticus confer more diverse microbiota; • The core microbiome of T. stylifera accounted for the majority of its total microbiome, forming more permanent associations that can hinder the recruitment of opportunistic microbes introduced by filter-feeding; • Predicted functional profiles showed an enrichment of a nitrogen metabolic pathway in the copepod core microbiota, mostly during summer when the shallow coastal waters are nitrogen depleted. Research Output Publication 1 Trained personnel 2 Feeding Strategy and Dietary Preference Shape the Microbiome of Epipelagic Copepods in a Warm Nutrientimpoverished Ecosystem Dr. Dalit Meron Morris Kahn Marine Research Station, University of Haifa Dr. Tamar Guy-Haim Israel Oceanographic and Limnological Research (IOLR) Fig 1. Copepod microbiome beta diversity. A) Principal coordinates analysis (PCoA) using Bray-Curtis distances of the copepod microbial communities, C. ponticus, O. nana and T. stylifera. B) Chord diagram plots showing the microbial taxa that are mostly present in the copepod species across the sampling seasons.
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