NMFS Satellite group
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Where's the Data?
Telemetry data from tagged northern fur seals overlain on fields of SSH and geostrophic velocity demonstrates the interaction between the animals and oceanographic eddies. From Ream et al. (2005), Deep Sea Research II, 52, 823-843.
The use of environmental satellite data such as sea-surface height (SSH), sea-surface temperature (SST) and surface chlorophyll, in conjunction with satellite telemetry information provides critical insight into classifying the oceanographic habitats utilized by species of interest to better understand their behavior and migration patterns. This study done by AFSC scientists found that northern fur seals do not follow coastal or bathymetric features as they cross the North Pacific Ocean, but instead track water movement of the Alaska Gyre and the North Pacific Current. Analysis of satellite data indicated that winter foraging areas varied geographically and were associated with eddies, the subarctic-subtropical transition region, and areas that undergo coastal mixing due to the California Current. The results indicate that fur seals may cue on a variety of oceanographic features that aid in reducing energetic expenditures and optimize foraging opportunities.
| Large Marine Ecosystems Program|
As part of NOAA's ecosystem-based approach to management of marine fisheries, NEFSC scientists are involved with developing modules for characterizing and assessing Large Marine Ecosystems (LMEs). LMEs are regions of ocean space encompassing coastal areas from river basins and estuaries to the seaward boundaries of continental shelves and the outer margins of the major current systems. They are relatively large regions on the order of 200,000 km2 or greater, characterized by distinct bathymetry, hydrography, productivity, and trophically dependent populations. On a global scale, 64 LMEs produce 95% of the world's annual marine fishery biomass yields. Within their waters, most of the global ocean pollution, overexploitation, and coastal habitat alteration occur. The spatial and temporal coverage of satellite data makes it a critical component to monitor and assess the productivity of LMEs.
Annual satellite-derived Primary Productivity and the outlines of the 64 defined Large Marine Ecosystems. From Sherman et al., Marine Ecology Progress Series, 300, 275-279, 2005.
Animation of chlorophyll and SST off the East Coast during 2002, supplied by Jay O'Reilly (NMFS/NEFSC).
Domoic Acid levels (circles) measured off of Washington during an ECOHAB survey, overlaid on top of satellite chlorophyll. Image courtesy of Vera Trainer, NMFS/NWFSC.
The NWFSC has been active in research on marine biotoxins and harmful algal blooms (HABs) for over 50 years. The Pacific region is unique, not only because of its size and the challenge of monitoring thousands of miles of coastline, but because it is the location of the some of the highest levels of biotoxins in the world and the site of HAB incidents that have killed both marine mammals and humans. Satelite imagery, such as SST and chlorophyll data, is used to characterize the larger-scale environmental conditional associated with HAB events, in order to better understand their underlaying causes, and to track the movement of water to monitor the development and evolution of HAB events.
Near-real time satellite data is used routinely within NMFS to identify ocean fronts and other features in planning and conducting research cruises to optimize sampling while at sea.
North Pacific "Transition Zone Chlorophyll Front" (TZCF) |
Pelagic ecosystem dynamics on all temporal scales may be driven by the dynamics of very specialized oceanic features. One such feature that has been described by PIFSC scientists is the basin-wide chlorophyll front located at the boundary between the low and high chlorophyll subtropical gyres. Global satellite maps of surface chlorophyll clearly show this feature in all oceans. In the Pacific, the front is over 8,000 km long and seasonally migrates north and south about 1,000 km. In the winter it is located at about latitudes 30°-35°N and in the summer at about 40°-45°N. Since this chlorophyll front moves seasonally between the southern and northern limits of the Transition Zone, it was named the Transition Zone Chlorophyll Front or TZCF. Satellite telemetry data on movements of loggerhead turtles, Laysan albatross, and detailed fisheries data for North Pacific albacore tuna indicate that all of these species forage at this front and in some cases travel along it as they migrate across the North Pacific. The front is easily monitored with ocean color satellite remote sensing. Interannual variation in the position and strength of the TZCF has been observed and appears to have impacts on marine resources.
|Loggerhead turtle tracks along the TZCF during Feb. 2001. From Polovina et al. (2000), Fisheries Oceanography, 9, 71-82.|
Discovering Habitat? |
Large chlorophyll blooms, seen with ocean color satellite data, frequently develop in the late summer in the oligotrophic subtropical Pacific northeast of Hawaii. They have been observed in 11 of 16 years of satellite ocean color data (CZCS, OCTS and SeaWiFS) and can last up to 4-5 months. The blooms have never been intentionally sampled, and it not certain what is causing them. Work done at the SWFSC has suggested that that they are fuelled by either nitrogen fixation or by new N brought in by the vertical migration of Rhizosolenia diatom mats between the surface and the nutricline. The two most consistent aspects of the blooms are the timing of their development, occurring in late summer, and their location, centered along 30°N between 135°-155°W. The blooms could have an impact on higher tropic levels in the ecosystem, as the region where they develop is also within important habitat for highly migratory species such as albacore, bigeye tuna and billfishes, and within the target area of important longline fisheries. The blooms may represent a highly localized food source for prey species, and could be important congregation points at various parts of these predators' life histories.
|Chlorophyll bloom in the oligotrophic Pacific in Oct. 2000. This bloom was approximately the size of the state of New Mexico. From Wilson, GRL, 2003 and Wilson et al., J. Mar. Systems, 2006, in press.|
Fish egg distributions from CalCOFI cruises in 1998 (an El Niño year) and 1999 (a La Niña year) overlain over SST imagery. Images courtesy of Rich Charter, NMFS/SWFSC. More images at http://swfsc.nmfs.noaa.gov/frd/CalCOFI/CurrentCruise/sardmaps.htm See also Lynn (2003), Fish. Oceanogr., 12, 541-553.
Interpreting Interannual Variability|
Scientists at the SWFSC are actively involved in the state-federal California Cooperative Oceanic Fisheries Investigations (CalCOFI), a consortium of state and federal research agencies whose scientists conduct integrated research on the physical, chemical, and ecology of the California Current. The CalCOFI program was originally established in 1949 to investigate factors relating to the collapse of the sardine fishery off California, but over the years its research has broadened to include other species as well. Scientists at SWFSC study fish and egg larvae using egg counts provided by the Continuous Underway Fish Egg Sampler (CUFES). The spatial pattern of sardine spawning is coupled to sea surface temperature (SST), this is particularly evident by the contrast in onshore vs offshore distribution between the 1998 El Niño and 1999 La Niña. The information provided by satellite data can be used as an aid for delineating the boundaries of sardine spawning habitat.