Current ecotoxicity testing needs among selected U.S. federal agencies.

U.S. regulatory and research agencies use ecotoxicity test data to assess the hazards associated with substances that may be released into the environment, including but not limited to industrial chemicals, pharmaceuticals, pesticides, food additives, and color additives. These data are used to conduct hazard assessments and evaluate potential risks to aquatic life (e.g., invertebrates, fish), birds, wildlife species, or the environment. To identify opportunities for regulatory uses of non-animal replacements for ecotoxicity tests, the needs and uses for data from tests utilizing animals must first be clarified. Accordingly, the objective of this review was to identify the ecotoxicity test data relied upon by U.S. federal agencies. The standards, test guidelines, guidance documents, and/or endpoints that are used to address each of the agencies' regulatory and research needs regarding ecotoxicity testing are described in the context of their application to decision-making. Testing and information use, needs, and/or requirements relevant to the regulatory or programmatic mandates of the agencies taking part in the Interagency Coordinating Committee on the Validation of Alternative Methods Ecotoxicology Workgroup are captured. This information will be useful for coordinating efforts to develop and implement alternative test methods to reduce, refine, or replace animal use in chemical safety evaluations.

Global Estimates of the Energy Transfer From the Wind to the Ocean, With Emphasis on Near-Inertial Oscillations.

Estimates of the kinetic energy transfer from the wind to the ocean are often limited by the spatial and temporal resolution of surface currents and surface winds. Here we examine the wind work in a pair of global, very high-resolution (1/48° and 1/24°) MIT general circulation model simulations in Latitude-Longitude-polar Cap (LLC) configuration that provide hourly output at spatial resolutions of a few kilometers and include tidal forcing. A cospectrum analysis of wind stress and ocean surface currents shows positive contribution at large scales (>300 km) and near-inertial frequency and negative contribution from mesoscales, tidal frequencies, and internal gravity waves. Larger surface kinetic energy fluxes are in the Kuroshio in winter at large scales (40 mW/m2) and mesoscales (-30 mW/m2). The Kerguelen region is dominated by large scale (∼20 mW/m2), followed by inertial oscillations in summer (13 mW/m2) and mesoscale in winter (-12 mW/m2). Kinetic energy fluxes from internal gravity waves (-0.1 to -9.9 mW/m2) are generally stronger in summer. Surface kinetic energy fluxes in the LLC simulations are 4.71 TW, which is 25-85% higher than previous global estimates from coarser (1/6-1/10°) general ocean circulation models; this is likely due to improved representation of wind variability (6-hourly, 0.14°, operational European Center for Medium-Range Weather Forecasts). However, the low wind power input to the near-inertial frequency band obtained with LLC (0.16 TW) compared to global slab models suggests that wind variability on time scales less than 6 hr and spatial scales less than 15 km are critical to better representing the wind power input in ocean circulation models.

Pathways of ocean heat towards Pine Island and Thwaites grounding lines.

In the Amundsen Sea, modified Circumpolar Deep Water (mCDW) intrudes into ice shelf cavities, causing high ice shelf melting near the ice sheet grounding lines, accelerating ice flow, and controlling the pace of future Antarctic contributions to global sea level. The pathways of mCDW towards grounding lines are crucial as they directly control the heat reaching the ice. A realistic representation of mCDW circulation, however, remains challenging due to the sparsity of in-situ observations and the difficulty of ocean models to reproduce the available observations. In this study, we use an unprecedentedly high-resolution (200 m horizontal and 10 m vertical grid spacing) ocean model that resolves shelf-sea and sub-ice-shelf environments in qualitative agreement with existing observations during austral summer conditions. We demonstrate that the waters reaching the Pine Island and Thwaites grounding lines follow specific, topographically-constrained routes, all passing through a relatively small area located around 104°W and 74.3°S. The temporal and spatial variabilities of ice shelf melt rates are dominantly controlled by the sub-ice shelf ocean current. Our findings highlight the importance of accurate and high-resolution ocean bathymetry and subglacial topography for determining mCDW pathways and ice shelf melt rates.

Correction to: The One Health Approach to Toxoplasmosis: Epidemiology, Control, and Prevention Strategies.

This article was originally published electronically on the publisher's internet portal (currently SpringerLink) on April 3, 2019 without open access.

The influence of geostrophic strain on oceanic ageostrophic motion and surface chlorophyll.

Oceanic submesoscale ageostrophic processes have been progressively recognized as an important upwelling mechanism to close the nutrient budget and sustain the observed primary production of phytoplankton in the euphotic layer. Their relatively small spatio-temporal scales (of 1~10 km and a few days) have hindered a systematic observational quantification of the submesoscale ageostrophic flow variability and its impact on ocean biogeochemistry. By combining surface drifters, satellite altimetry and satellite ocean-color data, we detect that when the strain rate of mesoscale surface geostrophic flow is strong, it favors a higher ageostrophic kinetic energy level and an increase in surface chlorophyll concentration. The strain-induced frontal processes are characterized by a surface chlorophyll increase and secondary ageostrophic upwelling along the light side of the oceanic density front. Further analysis indicates that the balanced ageostrophic motions with longer time scales are more effective in inducing chlorophyll increase than the unbalanced shorter time-scale wave motions.

Submesoscale ocean fronts act as biological hotspot for southern elephant seal.

The area west of the Kerguelen Islands (20-70°E/45-60°S) is characterized by a weak mesoscale activity except for a standing meander region of the Antarctic Circumpolar Current (ACC) localized between 20 and 40°E. A unique bio-physical dataset at high-resolution collected by a southern elephant seal (Mirounga leonina) reveals a conspicuous increase in foraging activity at the standing meander site up to 5 times larger than during the rest of her three-month trip west of the Kerguelen Islands. Here, we propose a physical explanation for such high biological activity based on the study of small-scale fronts with scales of 5 to 20 km, also called submesoscales. The standing meander is associated with intensified frontal dynamics at submesoscale, not observed in the rest of the region. Results shed new light on the spatial distribution of submesoscale fronts in the under-sampled area west of the Kerguelen plateau and emphasize their importance for upper trophic levels. Despite that most elephant seals target foraging grounds east of the Kerguelen Plateau, our findings suggest that excursions to the west are not accidental, and may be explained by the recurrently elevated physical and biological activity of the site. As such, other standing meanders of the ACC may also act as biological hotspots where trophic interactions are stimulated by submesoscale turbulence.

The One Health Approach to Toxoplasmosis: Epidemiology, Control, and Prevention Strategies.

One Health is a collaborative, interdisciplinary effort that seeks optimal health for people, animals, plants, and the environment. Toxoplasmosis, caused by Toxoplasma gondii, is an intracellular protozoan infection distributed worldwide, with a heteroxenous life cycle that practically affects all homeotherms and in which felines act as definitive reservoirs. Herein, we review the natural history of T. gondii, its transmission and impacts in humans, domestic animals, wildlife both terrestrial and aquatic, and ecosystems. The epidemiology, prevention, and control strategies are reviewed, with the objective of facilitating awareness of this disease and promoting transdisciplinary collaborations, integrative research, and capacity building among universities, government agencies, NGOs, policy makers, practicing physicians, veterinarians, and the general public.

Ocean submesoscales as a key component of the global heat budget.

Recent studies highlight that oceanic motions associated with horizontal scales smaller than 50 km, defined here as submesoscales, lead to anomalous vertical heat fluxes from colder to warmer waters. This unique transport property is not captured in climate models that have insufficient resolution to simulate these submesoscale dynamics. Here, we use an ocean model with an unprecedented resolution that, for the first time, globally resolves submesoscale heat transport. Upper-ocean submesoscale turbulence produces a systematically-upward heat transport that is five times larger than mesoscale heat transport, with winter-time averages up to 100 W/m2 for mid-latitudes. Compared to a lower-resolution model, submesoscale heat transport warms the sea surface up to 0.3 °C and produces an upward annual-mean air-sea heat flux anomaly of 4-10 W/m2 at mid-latitudes. These results indicate that submesoscale dynamics are critical to the transport of heat between the ocean interior and the atmosphere, and are thus a key component of the Earth's climate.

Submesoscale transition from geostrophic flows to internal waves in the northwestern Pacific upper ocean.

With radar interferometry, the next-generation Surface Water and Ocean Topography satellite mission will improve the measured sea surface height resolution down to 15 km, allowing us to investigate for the first time the global upper ocean variability at the submesoscale range. Here, by analysing shipboard Acoustic Doppler Current Profiler measurements along 137°E in the northwest Pacific of 2004-2016, we show that the observed upper ocean velocities are comprised of balanced geostrophic flows and unbalanced internal waves. The transition length scale, Lt, separating these two motions, is found to depend strongly on the energy level of local mesoscale eddy variability. In the eddy-abundant western boundary current region of Kuroshio, Lt can be shorter than 15 km, whereas Lt exceeds 200 km along the path of relatively stable North Equatorial Current. Judicious separation between the geostrophic and internal wave signals represents both a challenge and an opportunity for the Surface Water and Ocean Topography mission.

Impact of oceanic-scale interactions on the seasonal modulation of ocean dynamics by the atmosphere.

Ocean eddies (with a size of 100-300 km), ubiquitous in satellite observations, are known to represent about 80% of the total ocean kinetic energy. Recent studies have pointed out the unexpected role of smaller oceanic structures (with 1-50 km scales) in generating and sustaining these eddies. The interpretation proposed so far invokes the internal instability resulting from the large-scale interaction between upper and interior oceanic layers. Here we show, using a new high-resolution simulation of the realistic North Pacific Ocean, that ocean eddies are instead sustained by a different process that involves small-scale mixed-layer instabilities set up by large-scale atmospheric forcing in winter. This leads to a seasonal evolution of the eddy kinetic energy in a very large part of this ocean, with an amplitude varying by a factor almost equal to 2. Perspectives in terms of the impacts on climate dynamics and future satellite observational systems are briefly discussed.

Cyclone-anticyclone asymmetry in geophysical turbulence.

We address the problem of cyclone-anticyclone asymmetry in geophysical turbulence using a direct numerical simulation with high Reynolds number Re∼15,000 that includes an active upper boundary and interior dynamics. The regime, characterized by a finite Rossby number (Ro∼0.6) strongly departs from the classical quasigeostrophic regime. The numerical resolution is pushed to the limit of today's supercomputer capabilities ensuring more than two decades free of viscous effects. The results show a strong cyclonic dominance in the upper layers that is stronger for filaments than for vortices. This is in contrast with similar studies that have no active upper boundary which reported either anticyclone dominance or a symmetry between cyclones and anticyclones in the upper layers. This highlights the impact of boundary dynamics on geophysical turbulence.

The oceanic vertical pump induced by mesoscale and submesoscale turbulence.

The motivation to study the vertical exchanges of tracers associated with mesoscale eddies is that the mean concentration of most oceanic tracers changes rapidly with depth. Because mesoscale processes may transport these tracers vertically, biogeochemists hypothesized that these vertical exchanges may strongly affect global tracer budgets. This hypothesis has motivated a large number of biogeochemical studies that we review here by focusing on the significant advances that have been achieved and the remaining issues and uncertainties. The main question that emerges concerns the importance of the submesoscales (10 km in the horizontal) in these vertical exchanges. Independently, in the past decade, fluid dynamicists examined the three-dimensional properties of submesoscales generated by a mesoscale (100 km in the horizontal) turbulent eddy field. We review their results and discuss how the vertical exchanges associated with these submesoscales may answer the issues raised by biogeochemical studies and inspire future directions.

Chlorfenapyr and mallard ducks: overview, study design, macroscopic effects, and analytical chemistry.

The first commercial pesticide derived from a class of compounds known as halogenated pyrroles was registered for use in the United States in 2001. Chlorfenapyr degrades slowly in soil, sediment, and water and is highly toxic to birds. Information on biochemical or histological endpoints in birds is lacking; therefore, a two-year study was conducted to provide information needed to develop diagnostic criteria for chlorfenapyr toxicosis. In the first year, male mallard ducks were fed concentrations of 0, 2, 5, or 10 ppm technical chlorfenapyr or 5 ppm of a formulated product in their diet during a 10-week chronic exposure study. Survival, body weight, feed consumption (removal), behavior, and molt progression were monitored. Feed and liver were analyzed for chlorfenapyr and two metabolites. Five of 10 ducks in the 10-ppm group died, and neurotoxic effects were observed in the 5- and 10-ppm groups. Feed removal increased for ducks receiving chlorfenapyr and body weights of 5- and 10-ppm ducks were reduced. Loss of body fat, muscle atrophy, and bile retention were suggestive of metabolic disruption or a decreased ability to digest and absorb nutrients. Liver and kidney weights and liver and kidney weight/body weight ratios exhibited a positive response to concentrations of chlorfenapyr in the diet. Emaciation and elevated organ weight/body weight ratios are candidates for a suite of indicators of chronic chlorfenapyr exposure. Liver is the preferred tissue for chemical confirmation of exposure.