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  • 1
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    Danger of zooplankton feeding : the fluid signal generated by ambush-feeding copepods (2010)
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    Publication Date: 2022-05-25
    Description: Author Posting. © The Authors, 2010. This is the author's version of the work. It is posted here by permission of The Royal Society for personal use, not for redistribution. The definitive version was published in Proceedings of the Royal Society B: Biological Sciences 277 (2010): 3229-3237, doi:10.1098/rspb.2010.0629.
    Description: Zooplankton feed in either of three ways: they generate a feeding current, cruise through the water, or they are ambush feeders. Each mode generates different hydrodynamic disturbances and hence exposes the grazers differently to mechanosensory predators. Ambush feeders sink slowly and therefore perform occasional upward repositioning jumps. We quantified the fluid disturbance generated by repositioning jumps in a mm-sized copepod (Re ~ 40). The kick of the swimming legs generates a viscous vortex ring in the wake; another ring of similar intensity but opposite rotation is formed around the decelerating copepod. A simple analytical model, that of an impulsive point force, properly describes the observed flow field as a function of the momentum of the copepod, including the translation of the vortex and its spatial extension and temporal decay. We show that the time-averaged fluid signal and the consequent predation risk is much less for an ambush feeding than a cruising or hovering copepod for small individuals, while the reverse is true for individuals larger than about 1 mm. This makes inefficient ambush feeding feasible in small copepods and is consistent with the observation that ambush feeding copepods in the ocean are all small, while larger species invariably use hovering or cruising feeding strategies.
    Description: TK was supported by a grant from the Danish Research Council and by a Niels Bohr Fellowship to TK and HJ was supported by National Science Foundation grants NSF OCE-0352284 & IOS-0718506.
    Keywords: Viscous vortex ring ; Copepod jump ; Acartia tonsa ; Optimal foraging
    Repository Name: Woods Hole Open Access Server
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  • 2
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    Comment: On phytoplankton perception by calanoid copepods (2016)
    John Wiley & Sons
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    Publication Date: 2022-05-25
    Description: Author Posting. © Association for the Sciences of Limnology and Oceanography, 2016. This article is posted here by permission of Association for the Sciences of Limnology and Oceanography for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography 61 (2016): 1163–1168, doi:10.1002/lno.10294.
    Description: Three publications recently reported that calanoid copepods, feeding on phytoplankton cells by using a feeding current, perceived such cells by mechanoperception. There was no evidence of remote chemically-mediated perception of those cells. These observations differ from earlier findings that feeding-current producing calanoids are able to detect phytoplankton cells by chemoperception at a distance from their particle-collecting setae of their cephalic appendages. The results on mechanoperception and the earlier published data on chemoperception will be presented and discussed. In addition, the concentration of chemicals within the phycosphere of food cells will be re-examined. We conclude that chemoperception of phytoplankton cells by calanoid copepods in a feeding current is feasible.
    Repository Name: Woods Hole Open Access Server
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  • 3
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    Plankton reach new heights in effort to avoid predators (2012)
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    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of The Royal Society for personal use, not for redistribution. The definitive version was published in Proceedings of the Royal Society B: Biological Sciences 279 (2012): 2786-2792, doi:10.1098/rspb.2012.0163.
    Description: The marine environment associated with the air-water interface (neuston) provides an important food source to pelagic organisms where subsurface prey is limited. However, studies on predator-prey interactions within this environment are lacking. Copepods are known to produce strong escape jumps in response to predators but must contend with a low Reynolds number environment where viscous forces limit escape distance. All previous work on copepods interaction with predators has focused on a liquid environment. Here, we describe a novel anti-predator behavior in two neustonic copepod species where individuals frequently exit the water surface and travel many times their own body length through air to avoid predators. Using both field recordings with natural predators and high speed laboratory recordings we obtain detailed kinematics of this behavior, and estimate energetic cost associated with this behavior. We demonstrate that despite losing up to 88% of their initial kinetic energy, copepods which break the water surface travel significantly further than escapes underwater and successfully exit the perceptive field of the predator. This behavior provides an effective defense mechanism against subsurface feeding visual predators and the results provide insight into trophic interactions within the neustonic environment.
    Description: This work was supported by grants from the National Science Foundation, USA to EJB (NSF OCE-0452159), to HJ (NSF OCE-1129496).
    Repository Name: Woods Hole Open Access Server
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  • 4
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    Waves in the Red Sea : response to monsoonal and mountain gap winds (2013)
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    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Continental Shelf Research 65 (2013): 1-13, doi:10.1016/j.csr.2013.05.017.
    Description: An unstructured grid, phase-averaged wave model forced with winds from a high resolution atmospheric model is used to evaluate wind wave conditions in the Red Sea over an approximately 2-year period. The Red Sea lies in a narrow rift valley, and the steep topography surrounding the basin steers the dominant wind patterns and consequently the wave climate. At large scales, the model results indicated that the primary seasonal variability in waves was due to the monsoonal wind reversal. During the winter, monsoon winds from the southeast generated waves with mean significant wave heights in excess of 2 m and mean periods of 8 s in the southern Red Sea, while in the northern part of the basin waves were smaller, shorter period, and from northwest. The zone of convergence of winds and waves typically occurred around 19-20˚N, but the location varied between 15 to 21.5˚N. During the summer, waves were generally smaller and from the northwest over most of the basin. While the seasonal winds oriented along the axis of the Red Sea drove much of the variability in the waves, the maximum wave heights in the simulations were not due to the monsoonal winds but instead were generated by localized mountain wind jets oriented across the basin (roughly east-west). During the summer, a mountain wind jet from the Tokar Gap enhanced the waves in the region of 18 and 20˚N, with monthly mean wave heights exceeding 2 m and maximum wave heights of 14 m during a period when the rest of the Red Sea was relatively calm. Smaller mountain gap wind jets along the northeast coast created large waves during the fall and winter, with a series of jets providing a dominant source of wave energy during these periods. Evaluation of the wave model results against observations from a buoy and satellites found that the spatial resolution of the wind model significantly affected the quality of the wave model results. Wind forcing from a 10-km grid produced higher skills for waves than winds from a 30-km grid, largely due to under-prediction of the mean wind speed and wave height with the coarser grid. The 30-km grid did not resolve the mountain gap wind jets, and thus predicted lower wave heights in the central Red Sea during the summer and along the northeast coast in the winter.
    Description: This research is based on work supported by Award No. USA00001, USA00002, KSA00011, made by the King Abdullah University of Science and Technology (KAUST) in Saudi Arabia.
    Repository Name: Woods Hole Open Access Server
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  • 5
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    The Tokar Gap jet : regional circulation, diurnal variability, and moisture transport based on numerical simulations (2015)
    American Meteorological Society
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    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2015. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 28 (2015): 5885–5907, doi:10.1175/JCLI-D-14-00635.1.
    Description: The structure, variability, and regional connectivity of the Tokar Gap jet (TGJ) are described using WRF Model analyses and supporting atmospheric datasets from the East African–Red Sea–Arabian Peninsula (EARSAP) region during summer 2008. Sources of the TGJ’s unique quasi-diurnal nature and association with atypically high atmospheric moisture transport are traced back to larger-scale atmospheric dynamics influencing its forcing. These include seasonal shifts in the intertropical convergence zone (ITCZ), variability of the monsoon and North African wind regimes, and ties to other orographic flow patterns. Strong modulation of the TGJ by regional processes such as the desert heating cycle, wind convergence at the ITCZ surface front, and the local land–sea breeze cycle are described. Two case studies present the interplay of these influences in detail. The first of these was an “extreme” gap wind event on 12 July, in which horizontal velocities in the Tokar Gap exceeded 26 m s−1 and the flow from the jet extended the full width of the Red Sea basin. This event coincided with development of a large mesoscale convective complex (MCC) and precipitation at the entrance of the Tokar Gap as well as smaller gaps downstream along the Arabian Peninsula. More typical behavior of the TGJ during the 2008 summer is discussed using a second case study on 19 July. Downwind impact of the TGJ is evaluated using Lagrangian model trajectories and analysis of the lateral moisture fluxes (LMFs) during jet events. These results suggest means by which TGJ contributes to large LMFs and has potential bearing upon Sahelian rainfall and MCC development.
    Description: This work was supported by a grant from the King Abdullah University of Science and Technology (KAUST) as well as National Science Foundation Grant OCE0927017 and from DOD (MURI) Grant N000141110087, administered by the Office of Naval Research.
    Description: 2016-02-01
    Keywords: Africa ; Orographic effects ; Monsoons ; Atmosphere-land interaction ; Atmosphere-ocean interaction ; Hydrometeorology
    Repository Name: Woods Hole Open Access Server
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  • 6
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    Why does the jumping ciliate Mesodinium rubrum possess an equatorially located propulsive ciliary belt? (2011)
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    Publication Date: 2022-05-25
    Description: Author Posting. © The Author, 2011. This is the author's version of the work. It is posted here by permission of Oxford University Press for personal use, not for redistribution. The definitive version was published in Journal of Plankton Research 33 (2011): 998-1011, doi:10.1093/plankt/fbr007.
    Description: It has long been thought that jumping by the ciliate Mesodinium rubrum can enhance its nutrient uptake. However, jumping can be energetically costly and also dangerous by inducing hydrodynamic disturbances detectable to rheotactic predators. Here, a computational fluid dynamics (CFD) model, driven by published empirical data, is developed to simulate the jump-induced unsteady flow as well as chemical field around a self-propelled jumping ciliate. The associated phosphorus uptake, hydrodynamic signal strength, mechanical energy cost and Froude propulsion efficiency are also calculated. An equatorial ciliary belt (ECB), i.e. the morphology used by M. rubrum for propulsion, is considered. For comparison purpose, three other strategies (pulled or pushed by cilia, or towed) are also considered. Comparison of the CFD results among the four strategies considered suggests: (1) jumping enhances phosphorus uptake with simulated values consistent with available field data; (2) the M. rubrum-like propulsion generates the weakest and spatially most limited hydrodynamic disturbance and therefore may effectively minimize the jump-induced predation risk; and (3) the M. rubrum-like propulsion achieves a high Froude propulsion efficiency (~0.78) and is least costly in mechanical energy expenditure among the three self-propelled strategies considered. Thus, using the ECB for propulsion can be essential in ensuring that M. rubrum is a successful ‘fast-jumping’ primary producer.
    Description: This work was supported by National Science Foundation grants NSF OCE-0323959 & IOS- 0718506 and an award from WHOI’s Ocean Life Institute to H.J.
    Keywords: Jumping ciliate ; Mesodinium rubrum ; Nutrient uptake ; Hydrodynamic signal ; Froude propulsion efficiency ; Computational fluid dynamics
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  • 7
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    Copepod manipulation of oil droplet size distribution (2019)
    Nature Research
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    Publication Date: 2022-05-25
    Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Uttieri, M., Nihongi, A., Hinow, P., Motschman, J., Jiang, H., Alcaraz, M., & Strickler, J. R. (2019). Copepod manipulation of oil droplet size distribution AU uttieri, M nihongi, A hinow, P motschman, J jiang, H alcaraz, M strickler, JR. Scientific Reports, 9, 547 , doi:10.1038/s41598-018-37020-9.
    Description: Oil spills are one of the most dangerous sources of pollution in aquatic ecosystems. Owing to their pivotal position in the food web, pelagic copepods can provide crucial intermediary transferring oil between trophic levels. In this study we show that the calanoid Paracartia grani can actively modify the size-spectrum of oil droplets. Direct manipulation through the movement of the feeding appendages and egestion work in concert, splitting larger droplets (Ø = 16 µm) into smaller ones (Ø = 4–8 µm). The copepod-driven change in droplet size distribution can increase the availability of oil droplets to organisms feeding on smaller particles, sustaining the transfer of petrochemical compounds among different compartments. These results raise the curtain on complex small-scale interactions which can promote the understanding of oil spills fate in aquatic ecosystems.
    Description: This research was made possible by a grant from The Gulf of Mexico Research Initiative. Data are publicly available through the Gulf of Mexico Research Initiative Information & Data Cooperative (GRIIDC) at https://data.gulfresearchinitiative.org (doi: 10.7266/N7H70CV7). MU was sponsored by the MOKA project (Modelling and Observation of zooplanKtonic orgAnisms; ID: RBFR10VF6M) financed by the Italian Ministry of Education, University and Research, and by SZN internal grant. PH was supported by the Simons Foundation grant “Collaboration on Mathematical Biology” (278436). JM was the financed by the Support for Undergraduate Research Fellows (SURF) and the Center for International Education (CIE), University of Wisconsin-Milwaukee. HJ was supported by NSF grant no. OCE-1433979. MA was funded by the Spanish research project TOPCOP (CTM2011–23480, from the Spanish Ministry of Education and Science, and 2009SGR-1283 from the Catalan Government). MU thanks Mark Pottek for the design of the MOKA project cartoon, and UWM for hospitality during a research stay in January 2017 supported by Simons Foundation (grant to PH). The authors have no competing interests. No ethical considerations apply. All symbols provided in Fig. 2 courtesy of the Integration and Application Network, University of Maryland Center for Environmental Science (ian.umces.edu/symbols/).
    Keywords: Ecosystem ecology ; Marine biology
    Repository Name: Woods Hole Open Access Server
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  • 8
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    Flow disturbances generated by feeding and swimming zooplankton (2014)
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    Publication Date: 2022-05-26
    Description: Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 111 (2014): 11,738-11,743, doi:10.1073/pnas.1405260111.
    Description: Interactions between planktonic organisms, such as detection of prey, predators, and mates, are often mediated by fluid signals. Consequently, many plankton predators perceive their prey from the fluid disturbances that it generates when it feeds and swims. Zooplankton should therefore seek to minimize the fluid disturbance that they produce. By means of particle image velocimetry, we describe the fluid disturbances produced by feeding and swimming in zooplankton with diverse propulsion mechanisms, and ranging from 10-µm flagellates to 〉 mm-sized copepods. We show that zooplankton, in which feeding and swimming are separate processes, produce flow disturbances during swimming with a much faster spatial attenuation (velocity u varies with distance r as u ∝ r-3 to r-4), than that produced by zooplankton for which feeding and propulsion are the same process (u ∝ r-1 to r-2). As a result, the spatial extension of the fluid disturbance produced by swimmers is an order of magnitude smaller than that produced by feeders at similar Reynolds numbers. The ‘quiet’ propulsion of swimmers is achieved either through swimming erratically by short-lasting power-strokes, generating viscous vortex rings, or by ‘breast stroke swimming’. Both produce rapidly attenuating flows. The more ‘noisy’ swimming of those that are constrained by a need to simultaneously feed is due to constantly beating flagella or appendages that are positioned either anteriorly or posteriorly on the (cell) body. These patterns transcend differences in size and taxonomy and have thus evolved multiple times, suggesting a strong selective pressure to minimize predation risk.
    Description: The Centre for Ocean Life is a VKR Center of Excellence funded by the Villum Foundation. The work was further supported by a grant from the Danish Council for Independent Research, Natural Sciences to TK, RJG was supported by CONICET and FONCyT (PICT 2438). HJ was supported by NSF grant OCE-1129496.
    Keywords: Predation risk ; Biological fluid dynamics ; Optimization
    Repository Name: Woods Hole Open Access Server
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  • 9
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    Oscillations in the near-field feeding current of a calanoid copepod are useful for particle sensing (2020)
    Nature Research
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    Publication Date: 2022-05-26
    Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Giuffre, C., Hinow, P., Jiang, H., & Strickler, J. R. Oscillations in the near-field feeding current of a calanoid copepod are useful for particle sensing. Scientific Reports, 9(1), (2019): 17742, doi: 10.1038/s41598-019-54264-1.
    Description: Calanoid copepods are small crustaceans that constitute a major element of aquatic ecosystems. Key to their success is their feeding apparatus consisting of sensor-studded mouth appendages that are in constant motion. These appendages generate a feeding current to enhance the encounter probability with food items. Additionally, sensing enables the organism to determine the position and quality of food particles, and to alter the near-field flow to capture and manipulate the particles for ingestion or rejection. Here we observe a freely swimming copepod Leptodiaptomus sicilis in multiple perspectives together with suspended particles that allow us to analyse the flow field created by the animal. We observe a highly periodic motion of the mouth appendages that is mirrored in oscillations of nearby tracer particles. We propose that the phase shift between the fluid and the particle velocities is sufficient for mechanical detection of the particles entrained in the feeding current. Moreover, we propose that an immersed algal cell may benefit from the excitation by increased uptake of dissolved inorganic compounds.
    Description: We acknowledge funding from the Simons Foundation (grant #278436 to PH) during two visits of HJ to Milwaukee. HJ was also supported by NSF grant OCE-1559062. We thank Dr. Russell Cuhel (School of Freshwater Sciences, University of Wisconsin - Milwaukee) for collecting the animals from Lake Michigan and four unknown readers for valuable comments.
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  • 10
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    Copepod feeding strategy determines response to seawater viscosity: videography study of two calanoid copepod species (2020)
    Company of Biologists
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    Publication Date: 2022-05-26
    Description: Author Posting. © Company of Biologists, 2020. This article is posted here by permission of Company of Biologists for personal use, not for redistribution. The definitive version was published in Journal of Experimental Biology (2020): jeb.220830, doi: 10.1242/jeb.220830.
    Description: Calanoid copepods, depending on feeding strategy, have different behavioral and biological controls on their movements, thereby responding differently to environmental conditions such as changes in seawater viscosity. To understand how copepod responses to environmental conditions are mediated through physical, physiological, and/or behavioral pathways, we used high-speed microvideography to compare two copepod species, Acartia hudsonica and Parvocalanus crassirostris, under different temperature, viscosity, and dietary conditions. Acartia hudsonica exhibited “sink and wait” feeding behavior and typically responded to changes in seawater viscosity; increased seawater viscosity reduced particle-capture behavior and decreased the size of the feeding current. In contrast, P. crassirostris continuously swam and did not show any behavioral or physical responses to changes in viscosity. Both species showed a physiological response to temperature, with reduced appendage beating frequency at cold temperatures, but this did not generally translate into effects on swimming speed, feeding flux, or active time. Both copepod species swam slower when feeding on diatom rather than dinoflagellate prey, showing that prey type mediates copepod behavior. These results differentiate species-specific behaviors and responses to environmental conditions, which may lead to better understanding of niche separation and latitudinal patterns in copepod feeding and movement strategies.
    Description: This study was supported by the National Science Foundation [OCE1634024 to N.F.; OCE-1433979 and OCE-1559062 to H.J.]; and by Stony Brook University [Graduate Council Fellowship and Turner Fellowship to A.S.T].
    Description: 2021-06-11
    Keywords: Copepods ; Zooplankton ; Seawater viscosity ; Feeding mechanism ; Micro-particle tracking velocimetry (µPTV)
    Repository Name: Woods Hole Open Access Server
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