GLOBEC 2000: GOA: Copepod and Euphausiid Growth and Reproduction

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A fundamental goal of the GLOBEC program is to understand the secondary production of the coastal Gulf of Alaska (GOA) and how the success of higher trophic levels, specifically salmon, are affected by the variability in the magnitude of secondary production seasonally, inter-annually, and at the decadal scale. Because of the highly advective nature of the GOA, it is necessary to establish the relative importance of local versus imported production. The PIs will determine the rates of development, growth and egg production for the dominant copepod and euphausiid species in the coastal GOA. They will determine the in situ rates inshore and offshore by incubation techniques employing artificial cohorts (copepods) and individual females (both copepods and euphausiids). Incubation techniques are the only appropriate methods for this region due to its highly advective nature. The proposed research will put the in situ rates in perspective by determining their maximal rates under food- saturated conditions in the laboratory. The investigators also will estimate the extent to which secondary production is food-limited in the field by determining the functional relationships of development, growth and egg production to body size, temperature and food regimes. Food regimes will be assessed in terms of chlorophyll and particulate organic carbon, plus the abundance and biomass of autotrophic and heterotrophic protists. In collaboration with other researchers in the GLOBEC program, the implications of physical versus biological processes on the success of salmon recruitment will be established and predicted.