The biological consequences of the Deepwater Horizon oil spill are unknown, especially for resident organisms. Here, we report results from a field study tracking the effects of contaminating oil across space and time in resident killifish during the first 4 mo of the spill event. Remote sensing and analytical chemistry identified exposures, which were linked to effects in fish characterized by genome expression and associated gill immunohistochemistry, despite very low concentrations of hydrocarbons remaining in water and tissues. Divergence in genome expression coincides with contaminating oil and is consistent with genome responses that are predictive of exposure to hydrocarbon-like chemicals and indicative of physiological and reproductive impairment. Oil-contaminated waters are also associated with aberrant protein expression in gill tissues of larval and adult fish. These data suggest that heavily weathered crude oil from the spill imparts significant biological impacts in sensitive Louisiana marshes, some of which remain for over 2 mo following initial exposures.

Category 4 Hurricane Kenneth (HK) experienced unpredicted rapid weakening when it stalled over a cold core eddy (CCE) on 19-20 September 2005, 2800 km SE of Hawaii. Maximum sea surface temperature (SST) cooling of 8-9°C and a minimum aerially averaged SST of 18.3°C (over 8750 km 2 ) characterized its cool wake. A 3-D mixed-layer model enabled estimation of enthalpy fluxes (latent and sensible heat), as well as the relative importance of slow translation speed (U h ) compared with the preexisting CCE. As U h dropped below 1.5 m s À1, enthalpy fluxes became negative, cutting off direct ocean energy flux to HK. Although HK's weakening was attributed to wind shear, our results indicate that slow U h and consequent intense SST cooling were the main causes. The tropical cyclone-intensified CCE experienced rapid growth in magnitude (À6 to À40 cm), increased diameter (60 to 350 km), elevated chlorophyll a for 4 months, and 12 month longevity.

The 2010 Deepwater Horizon Gulf of Mexico oil spill, the largest in U.S. history, highlights the environmental risks inherent in deepwater drilling. These risks were mitigated by rapid access to real-time satellite measurements from passive (optical, IR) and active (synthetic aperture radar, altimetry) sensors. This study employed satellite data, in tandem with in situ current and wind measurements, to track surface oil and to better understand the causes for observed large-scale motions during the 84 day episode. The analysis revealed the merger of three cyclonic eddies along the Loop Current's (LC's) northern margin, ultimately forming a larger and more vigorous cyclonic eddy, measuring 280 Â 130 km on 18 May. This larger cyclonic eddy, in tandem with a smaller anticyclonic eddy and a LC meander, controlled the motion of the oil/dispersant mixture into deepwater (maximum current speed of 2.25 m s À1), tripling the area of surface oiling from 9623 to 33,575 km 2. Two main events limited the flow of oil to the Florida Straits, the accumulation of oil within the merged eddy and the fact that this eddy did not move substantially for several months. The observed offshore entrainment of oil toward the LC was successfully hindcast using a particle-tracking model based on geostrophic currents computed from satellite altimetry. This assessment of circulation processes may help to advance numerical circulation modeling efforts in this region of rapid current variability in support of safer deepwater drilling in the northern Gulf.

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