A simple eddy kinetic energy parameterization of the oceanic vertical mixing is presented. The parameterization scheme is based on recent works on atmospheric turbulence modeling. It is designed to simulate vertical mixing at all depths, from the upper boundary layer down to the abyss. This scheme includes a single prognostic equation for the turbulent kinetic energy. The computation of the turbulent length scales is diagnostic, rather than prognostic. In weakly turbulent regions the simulated vertical diffusivity is inversely proportional to the Brunt-Vai'sala frequency. In the first validation experiments presented here, the vertical mixing scheme is embedded into a simple one-dimensional model and used for upper ocean simulations at two very different test sites: the station Papa in the Gulf of Alaska and the Long-Term Upper Ocean Study (LOTUS) mooring in the Sargasso Sea. At station Papa the model successfully simulates the seasonal evolution of the upper ocean temperature field. At LOTUS the focus is on a short 2-week period. A detailed analysis of the oceanic heat budget during that period reveals a large bias in the bulk-derived surface heat fluxes. After correction of the fluxes the model does well in simulating the evolution of the temperature and wind-driven current. In particular, the large observed diurnal cycles of the sea surface temperature are well reproduced. During the second (windy) week of the selected period the model accounts for about two thirds of the kinetic energy of the observed upper ocean currents at periods larger than 6 hours. The local wind forcing thus appears to be the dominant generation mechanism for the near-inertial motions, which are the most energetic. The velocity simulation is especially good at the low frequencies. During the second simulated week the model accounts for as much as 78% of the kinetic energy at subinertial frequencies. The simulated mean velocity profile is reminiscent of an Ekman spiral, in agreement with the observations. 1. 16,179 16,180 GASPAR ET AL.' A SIMPLE EDDY KINETIC ENERGY MODEL FOR VERTICAL MIXING nearly optimal assimilation techniques can be associated with their discretized form [Mort et al., 1988]. Such models thus meet our basic requirements. However, they have a main weak point in the determination of a turbulent master length scale [Mellor and Yamada, 1982]. The master length can be either specified as a function of different characteristic turbulent scales or computed from a prognostic equation. In most oceanic applications [e.g., Mellor and Durbin, 1975; Klein and Coantic, 1981; Martin, 1985; AndrO and Lacar-r&re, 1985], that length is specified and specially tailored for ML modeling. It is generally dependent on the Blackadar [1962] length scale which is meaningless when several isolated turbulent regions are present in the water column. This again limits the use of such schemes in boundary layer modeling as is the case for the bulk models. On the contrary, the prognostic equation for the master length [Mellor and Yamada, 1974] is gene...

Effective transboundary conservation of highly migratory marine animals requires international management cooperation as well as clear scientific information about habitat use by these species. Populations of leatherback turtles (Dermochelys coriacea) in the eastern Pacific have declined by >90% during the past two decades, primarily due to unsustainable egg harvest and fisheries bycatch mortality. While research and conservation efforts on nesting beaches are ongoing, relatively little is known about this population of leatherbacks' oceanic habitat use and migration pathways. We present the largest multi-year (2004–2005, 2005–2006, and 2007) satellite tracking dataset (12,095 cumulative satellite tracking days) collected for leatherback turtles. Forty-six females were electronically tagged during three field seasons at Playa Grande, Costa Rica, the largest extant nesting colony in the eastern Pacific. After completing nesting, the turtles headed southward, traversing the dynamic equatorial currents with rapid, directed movements. In contrast to the highly varied dispersal patterns seen in many other sea turtle populations, leatherbacks from Playa Grande traveled within a persistent migration corridor from Costa Rica, past the equator, and into the South Pacific Gyre, a vast, low-energy, low-productivity region. We describe the predictable effects of ocean currents on a leatherback migration corridor and characterize long-distance movements by the turtles in the eastern South Pacific. These data from high seas habitats will also elucidate potential areas for mitigating fisheries bycatch interactions. These findings directly inform existing multinational conservation frameworks and provide immediate regions in the migration corridor where conservation can be implemented. We identify high seas locations for focusing future conservation efforts within the leatherback dispersal zone in the South Pacific Gyre.

Tracks of marine animals in the wild, now increasingly acquired by electronic tagging of individuals, are of prime interest not only to identify habitats and high-risk areas, but also to gain detailed information about the behaviour of these animals. Using recent satellite-derived current estimates and leatherback turtle (Dermochelys coriacea) tracking data, we demonstrate that oceanic currents, usually neglected when analysing tracking data, can substantially distort the observed trajectories. Consequently, this will affect several important results deduced from the analysis of tracking data, such as the evaluation of the orientation skills and the energy budget of animals or the identification of foraging areas. We conclude that currents should be systematically taken into account to ensure the unbiased interpretation of tracking data, which now play a major role in marine conservation biology.

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The field of marine tagging and tracking has grown rapidly in recent years as tag sizes have decreased and the diversity of sensors has increased. Tag data provide a unique view on individual movement patterns, at different scales than shipboard surveys, and have been used to discover new habitat areas, characterize oceanographic features, and delineate stock structures, among other purposes. Due to the necessity for small tag-to-body size ratio, tags have largely been deployed on adult animals, resulting in a relative paucity of data on earlier life history stages. In this study, we reviewed tagging efforts on multiple life history stages for seabirds, marine mammals, marine turtles, and fish and enumerated studies focusing on each guild that targeted larvae, juveniles or hatchlings. We found that turtles and fish had higher proportion of studies focusing on juveniles (> 20%) than seabirds and marine mammals (<10%). On both juveniles and adults, tags were used in a targeted manner with passive and transmitting tags as the main tools for population demography and connectivity studies, while GPS and archival tags were used more frequently for habitat analyses and foraging ecology. These findings identify the need to focus on novel approaches in tagging multiple life history stages both to study marine predator ecology and to effectively manage marine populations.