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1. Resolving abrupt frontal gradients in zooplankton community composition and marine snow fields with an autonomous Zooglider

   https://doi.org/10.1002/lno.12642  

   Gastauer, Sven; Ohman, Mark D (July 2024, Limnology and Oceanography)

   Abstract An autonomousZooglidernavigated across the California Current Front into low salinity, minty waters characteristic of the California Current proper in both summers of 2019 and 2021. Diving to 400 m depth,Zooglidertransited another near‐surface frontal gradient somewhat inshore. These frontal gradients were generally associated with changes in intensity, size composition, and Diel Vertical Migration responses of acoustic backscatterers. They were also associated with pronounced changes in zooplankton community composition, as assessed by a shadowgraph imaging Zoocam. Zoocam detected a decline in concentrations of copepods, appendicularians, and marine snow in the offshore direction, and an overall shift in community structure to a higher proportion of carnivorous taxa (and, in 2019, of planktonic rhizaria). No taxon was consistently elevated at all the peak frontal gradients, but appendicularians, copepods, and rhizarians sometimes showed front‐related increases in concentration. Such frontal gradient regions represent relatively abrupt transitions to different communities of planktonic organisms and suspended marine snow particles, with consequences for predator–prey relationships and the dominant vectors of particle export into subsurface waters. 

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2. Zooglider ‐measured association of zooplankton with the fine‐scale vertical prey field

   https://doi.org/10.1002/lno.11920  

   Whitmore, Benjamin M.; Ohman, Mark D. (October 2021, Limnology and Oceanography)
3. Zooglider-Based Measurements of Planktonic Foraminifera in the California Current System

   https://doi.org/10.2113/gsjfr.49.4.390  

   Gaskell, Daniel E.; Ohman, Mark D.; Hull, Pincelli M. (October 2019, Journal of Foraminiferal Research)

   Abstract Spines and rhizopodia play an important role in the feeding behavior, symbiont ecology, shell geochemistry, and density and drag of planktonic foraminifera. However, there are few empirical data on planktonic foraminifera in situ, and these delicate structures are disturbed on capture. Here, we report spine and rhizopod measurements from underwater images obtained in the California Current System near La Jolla, California by Zooglider, a new autonomous zooplankton-sensing glider. Across all observed species, we find that spine length and flexibility correlate with test size and that spines increase the effective prey encounter volume of spinose foraminifera by two to three orders of magnitude. Our data also yielded several novel observations regarding hastigerinid foraminifera (Hastigerinella digitata and Hastigerina pelagica), a group of unusually large planktonic foraminifera that are abundant in our dataset below 250 m. First, the effective encounter volume of hastigerinid foraminifera can be very large: our largest specimen occupies almost 40 cm3 (about the size of a golf ball), while the median specimen occupies 5.3 cm3 (about the size of a cherry). Second, the majority of hastigerinid foraminifera in our dataset have asymmetric bubble capsules, which are most frequently oriented with their bubbles on the upward side of the test, consistent with the hypothesis that the bubble capsule is positively buoyant. Third, 16% of hastigerinid foraminifera in our dataset have dispersed bubble capsules with detached bubbles distributed along the spines and rhizopodia, consistent with a regular source of natural disturbance. Taken together, our observations suggest that hastigerinid foraminifera play a larger role as mesopelagic predators in the California Current System than previously recognized. 

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4. A comparison between Zooglider and shipboard net and acoustic mesozooplankton sensing systems

   https://doi.org/10.1093/plankt/fbz033  

   Whitmore, Benjamin M; Nickels, Catherine F; Ohman, Mark D (July 2019, Journal of Plankton Research)

   Abstract Some planktonic patches have markedly higher concentrations of organisms compared to ambient conditions and are <5 m in thickness (i.e. thin layers). Conventional net sampling techniques are unable to resolve this vertical microstructure, while optical imaging systems can measure it for limited durations. Zooglider, an autonomous zooplankton-sensing glider, uses a low-power optical imaging system (Zoocam) to resolve mesozooplankton at a vertical scale of 5 cm while making concurrent physical and acoustic measurements (Zonar). In March 2017, Zooglider was compared with traditional nets (MOCNESS) and ship-based acoustics (Simrad EK80). Zoocam recorded significantly higher vertically integrated abundances of smaller copepods and appendicularians, and larger gelatinous predators and mineralized protists, but similar abundances of chaetognaths, euphausiids, and nauplii. Differences in concentrations and size-frequency distributions are attributable to net extrusion and preservation artifacts, suggesting advantages of in situ imaging of organisms by Zooglider. Zoocam detected much higher local concentrations of copepods and appendicularians (53 000 and 29 000 animals m−3, respectively) than were resolvable by nets. The EK80 and Zonar at 200 kHz agreed in relative magnitude and distribution of acoustic backscatter. The profiling capability of Zooglider allows for deeper high-frequency acoustic sampling than conventional ship-based acoustics. 

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5. Autonomous and non-autonomous functions of the maize Shohai1 gene, encoding a RWP-RK putative transcription factor, in regulation of embryo and endosperm development

   https://doi.org/10.1111/tpj.13996  

   Mimura, Manaki; Kudo, Toru; Wu, Shan; McCarty, Donald R.; Suzuki, Masaharu (September 2018, The Plant Journal)