Retrospective Data Analysis

To augment the new data that will be collected during the monitoring and process-study components of the U.S. GLOBEC Northeast Pacific study, existing data (whether it is on paper, in computers, or in jars) should be more thoroughly analyzed than it has been. The focus of retrospective analysis should be on addressing the same questions that are the focus of the monitoring component (see page ), which relate to documenting natural variability in the ecosystems, and examining linkages between processes occurring at different time scales. Even widely used data sets such as the CalCOFI and COADS data could be more fully exploited for understanding ecosystem processes. Another type of data that could be explored is that recorded by the organisms themselves. One example is the records of fish scale and microscopic organism abundances from layered anaerobic sediments--some of these records extend into the past for thousands of years, with time resolution of a few years. Another example is the records of growth recorded in fish scales and otoliths. For salmon in particular, scales have been collected from fish for over 50 years. Those scale data could be used to examine how growth may have varied through time, perhaps in response to large-scale shifts in climate and ocean conditions.

Archived scales, otoliths or zooplankton samples could be used as sources of DNA to examine spatial and temporal patterns of genetic variability in the Northeast Pacific. Genetic variation that might exist among populations of species that span the two gyres could reflect another important aspect of coupling (or the lack of it) between the two systems. If populations of holo- or meroplanktonic species are differentiated across the two regions, this would imply barriers to genetic mixing, and possibly, different adaptive regimes in the two areas. Conversely, genetic homogeneity among regions would imply significant genetic mixing between them. Determining which situation (genetic differentiation vs. homogeneity) prevails could lead to insights regarding the relationship between broad-scale circulation patterns and population structures. It would also provide important baseline information for comparative studies between the two regions.

Prior U.S. GLOBEC reports (see esp. U.S. GLOBEC Rept. 11, 1994 and U.S. GLOBEC Rept. 15, 1996) review the types of data sets available for retrospective examination of the links between climate, physics and marine animal populations. Those sets include: 1) repetitive observations from satellites [e.g., AVHRR for SST; CZCS, OCTS (and future SeaWifs) for ocean color; altimeter for sea level height and geostrophic surface circulation; scatterometer for winds]; 2) time-series of point and gridded instrumental observations [e.g., sea level stations, buoy data, shore-based SST and salinity data, COADS, MOODS, precipitation and stream-flow records, FNMOC winds and pressure, climatic indices such as ENSO, upwelling, Aleutian Low]; 3) ocean surveys of in-situ biophysical data [e.g., CalCOFI survey, Ocean Station P, La Parouse program, Newport, OR hydrographic line; GAK 1]; 4) historical records of animal population changes [e.g., fisheries catch data, marine bird and mammal censuses, Japanese vessel survey data, Ocean Station P data]; 5) time series reconstructed from paleoecological data contained within marine sediments [e.g., fish abundance records from scales; microorganisms abundance patterns; perhaps measures of upwelling intensity from isotopic composition of organism hard parts].

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