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SeaFlow is an underway flow cytometer that provides continuous shipboard observations of the abundance and optical properties of small phytoplankton (, Measurement(s)planktonic material • temperature of water • salinity • light irradiance • plankton size distributionTechnology Type(s)flow cytometer • Temperature Sensor Device • salinometer • photometerFactor Type(s)time • locationSample Characteristic - OrganismCyanobacteria • Micromonas pusilla • Navicula transitans • Thalassiosira pseudonana • Thalassiosira weissflogii • Geminifera cryophila • Crocosphaera • Synechococcus sp. WH 8012 • Synechococcus sp. WH 6501 • Prochlorococcus eMED4 • Prochlorococcus eMIT9312 • Prochlorococcus AS9601 • Prochlorococcus 1314Sample Characteristic - Environmentoceanic sea surface microlayer biome • sea waterSample Characteristic - LocationNorth Pacific Ocean Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.10110755

The study of connectivity patterns in networks has brought novel insights across diverse fields ranging from neurosciences to epidemic spreading or climate. In this context, betweenness centrality has demonstrated to be a very effective measure to identify nodes that act as focus of congestion, or bottlenecks, in the network. However, there is not a way to define betweenness outside the network framework. By analytically linking dynamical systems and network theory, we provide a trajectory-based formulation of betweenness, called Lagrangian betweenness, as a function of Lyapunov exponents. This extends the concept of betweenness beyond the context of network theory relating hyperbolic points and heteroclinic connections in any dynamical system to the structural bottlenecks of the network associated with it. Using modeled and observational velocity fields, we show that such bottlenecks are present and surprisingly persistent in the oceanic circulation across different spatio-temporal scales and we illustrate the role of these areas in driving fluid transport over vast oceanic regions. Analyzing plankton abundance data from the Kuroshio region of the Pacific Ocean, we find significant spatial correlations between measures of diversity and betweenness, suggesting promise for ecological applications., MJF and ES-R are very grateful for support from the Simons Foundation: the Simons Collaboration on Computational BIOgeochemical modeling of Marine EcosystemS (CBIOMES #549931 to MJF). C.L. and E.H-G acknowledge financial support from the Spanish State Research Agency through the Maria de Maeztu Program for Units of Excellence in R&D (MDM-2017-0711).

The Kuroshio current separates from the Japanese coast to become the Kuroshio Extension (KE) characterized by a strong latitudinal density front, high levels of mesoscale (eddy) energy, and high ch...

We present a systematic study of the differences generated by coupling the same ecological–biogeochemical model to a 1°, coarse-resolution, and 1∕6°, eddy-permitting, global ocean circulation model to (a) biogeochemistry (e.g., primary production) and (b) phytoplankton community structure. Surprisingly, we find that the modeled phytoplankton community is largely unchanged, with the same phenotypes dominating in both cases. Conversely, there are large regional and seasonal variations in primary production, phytoplankton and zooplankton biomass. In the subtropics, mixed layer depths (MLDs) are, on average, deeper in the eddy-permitting model, resulting in higher nutrient supply driving increases in primary production and phytoplankton biomass. In the higher latitudes, differences in winter mixed layer depths, the timing of the onset of the spring bloom and vertical nutrient supply result in lower primary production in the eddy-permitting model. Counterintuitively, this does not drive a decrease in phytoplankton biomass but results in lower zooplankton biomass. We explain these similarities and differences in the model using the framework of resource competition theory, and find that they are the consequence of changes in the regional and seasonal nutrient supply and light environment, mediated by differences in the modeled mixed layer depths. Although previous work has suggested that complex models may respond chaotically and unpredictably to changes in forcing, we find that our model responds in a predictable way to different ocean circulation forcing, despite its complexity. The use of frameworks, such as resource competition theory, provides a tractable way to explore the differences and similarities that occur. As this model has many similarities to other widely used biogeochemical models that also resolve multiple phytoplankton phenotypes, this study provides important insights into how the results of running these models under different physical conditions might be more easily understood.

Ocean boundary current systems are key components of the climate system, are home to highly productive ecosystems, and have numerous societal impacts. Establishment of a global network of boundary current observing systems is a critical part of ongoing development of the Global Ocean Observing System. The characteristics of boundary current systems are reviewed, focusing on scientific and societal motivations for sustained observing. Techniques currently used to observe boundary current systems are reviewed, followed by a census of the current state of boundary current observing systems globally. The next steps in the development of boundary current observing systems are considered, leading to several specific recommendations. Fil: Todd, Robert E.. Woods Hole Oceanographic Institution; Estados Unidos Fil: Chavez, Francisco. Monterey Bay Aquarium Research Institute; Estados Unidos Fil: Clayton, Sophie. Old Dominion University; Estados Unidos Fil: Cravatte, Sophie E.. Centre National de la Recherche Scientifique. Institut de Recherche pour le Développement; Francia. Universite de Toulouse; Francia Fil: Goes, Marlos P.. University of Miami; Estados Unidos Fil: Graco, Michelle I.. Instituto del Mar del Peru; Perú Fil: Lin, Xiaopei. Ocean University of China; China Fil: Sprintall, Janet. University of California; Estados Unidos Fil: Zilberman, Nathalie V.. University of California; Estados Unidos Fil: Archer, Matthew. California Institute of Technology; Estados Unidos Fil: Arístegui, Javier. Universidad de Las Palmas de Gran Canaria; España Fil: Balmaseda, Magdalena A.. European Centre for Medium-Range Weather Forecasts; Reino Unido Fil: Bane, John M.. University of North Carolina; Estados Unidos Fil: Baringer, Molly O.. Atlantic Oceanographic and Meteorological Laboratory ; Estados Unidos Fil: Barth, John A.. State University of Oregon; Estados Unidos Fil: Beal, Lisa M.. University of Miami; Estados Unidos Fil: Brandt, Peter. Geomar-Helmholtz Centre for Ocean Research Kiel; Alemania Fil: Calil, Paulo H.. Universidade Federal do Rio Grande; Brasil Fil: Campos, Edmo. Universidade de Sao Paulo; Brasil Fil: Centurioni, Luca R.. University of California; Estados Unidos Fil: Chidichimo, María Paz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina Fil: Cirano, Mauro. Universidade Federal do Rio de Janeiro; Brasil Fil: Cronin, Meghan F.. National Oceanic and Atmospheric Administration. Pacific Marine Environmental Laboratory; Estados Unidos Fil: Curchitser, Enrique N.. Rutgers University; Estados Unidos Fil: Davis, Russ E.. University of California; Estados Unidos Fil: Dengler, Marcus. Geomar-Helmholtz Centre for Ocean Research Kiel; Alemania Fil: DeYoung, Brad. Memorial University of Newfoundland; Canadá Fil: Dong, Shenfu. University of Miami; Estados Unidos Fil: Escribano, Ruben. Universidad de Concepción; Chile Fil: Fassbender, Andrea J.. Monterey Bay Aquarium Research Institute; Estados Unidos

Western boundary currents support high primary production and carbon export. Here, we performed a survey of photosynthetic picoeukaryotes in the North Pacific Ocean in four transects crossing the Kuroshio Front. Prasinophyte algae comprised 85% of 18S rRNA gene sequences for photosynthetic taxa in the

Theoretical studies predict that competition for limited resources reduces biodiversity to the point of ecological instability, whereas strong predator/prey interactions enhance the number of coexisting species and limit fluctuations in abundances. In open ocean ecosystems, competition for low availability of essential nutrients results in relatively few abundant microbial species. The remarkable stability in overall cell abundance of the dominant photosynthetic cyanobacterium Prochlorococcus is assumed to reflect a simple food web structure strongly controlled by grazers and/or viruses. This hypothesized link between stability and ecological interactions, however, has been difficult to test with open ocean microbes because sampling methods commonly have poor temporal and spatial resolution. Here we use continuous techniques on two different winter-time cruises to show that Prochlorococcus cell production and mortality rates are tightly synchronized to the day/night cycle across the subtropical Pacific Ocean. In warmer waters, we observed harmonic oscillations in cell production and mortality rates, with a peak in mortality rate consistently occurring ∼6 h after the peak in cell production. Essentially no cell mortality was observed during daylight. Our results are best explained as a synchronized two-component trophic interaction with the per-capita rates of Prochlorococcus consumption driven either directly by the day/night cycle or indirectly by Prochlorococcus cell production. Light-driven synchrony of food web dynamics in which most of the newly produced Prochlorococcus cells are consumed each night likely enforces ecosystem stability across vast expanses of the open ocean. © 2015, National Academy of Sciences. All rights reserved.

[1] Plankton patchiness is ubiquitous in the oceans, and various physical and biological processes have been proposed as its generating mechanisms. However, a coherent statement on the problem is missing, because of both a small number of suitable observations and an incomplete understanding of the properties of reactive tracers in turbulent media. It has been suggested that horizontal advection may be the dominant process behind the observed distributions of phytoplankton and zooplankton, acting to mix tracers with longer reaction times (Rt) down to smaller scales. Conversely, the relative distributions of sea surface temperature and phytoplankton has been attributed to small-scale upwelling, where tracers with longer Rt are able to homogenize more than those with shorter reaction times. Neither of the above mechanisms can explain simultaneously the (relative) spectral slopes of temperature, phytoplankton, and zooplankton. Here, with a simple advection model and a large suite of numerical experiments, we concentrate on some of the physical processes influencing the relative distributions of tracers at the ocean surface, and we investigate (1) the impact of the spatial scale of tracer supply, (2) the role played by coherent eddies on the distribution of tracers with different Rt, and (3) the role of diffusion (so far neglected). We show that diffusion determines the distribution of temperature, regardless of the nature of the forcing. We also find that coherent structures together with differential diffusion of tracers with different Rt impact the tracer distributions. This may help in understanding the highly variable nature of observed plankton spectra.