US-GLOBEC NEP Phase IIIa-CCS: Effects of climate variability on Calanus dormancy patterns and population dynamics within the California Current
A. Leising [NOAA Pacific Fisheries Environmental Laboratory], J. Runge, C. Johnson [Both at Univ. of New Hampshire]

Project Summary

Intellectual Merit - Calanoid copepods are key organisms in the California Current (CC) region, consuming primary and secondary production at high rates, and they are in turn the prey for larval, juvenile, and small pelagic fish, other invertebrates, and certain seabirds. The growth and reproduction of calanoids is directly and indirectly affected by climate variability, as temperature affects the physiological rates of these organisms, and changes in copepod prey abundance or prey type due to climatic change will have an indirect effect. A critical period in the life of several calanoid species is their overwintering period, during which they leave the unproductive surface waters in mid summer- fall, remain at depth for several months, and then ascend to the surface in the springtime, usually coincident with the spring bloom. The timing of the reemergence of these copepods in spring relative to the seasonal timing of the spring bloom is likely critical for both the copepods population dynamics during the rest of the year, and for fueling the first-feeding of many other organisms, such as larval fish. Similarly, the timing of when these copepods enter their dormant state, thus greatly reducing their abundance within the surface layers, may be critical to the life history of other surface planktivores. Surprisingly, the physical and biological cues that both initiate and terminate the dormant phase of several key copepod species within the CC are poorly known.

The goal of this research is to test the hypothesis that the dormant phase of two major calanoid species, Calanus pacificus and Calanus marshallae, are in part controlled by changes in temperature and prey abundance. This hypothesis will be tested by two means. First, the existing data relating to the relative stage abundance and vertical distribution of the two target species for four distinct locations along the west coast of the U.S. and Canada will be compiled, and then compared to observational bio-physical data sets, specifically temperature and proxies for prey abundance, much of which were collected as part of the GLOBEC NEP program. Second, an Individual-Based Model (IBM) for each of the two species will be developed, based on several different conceptual models of how temperature and prey availability control the dormancy response. This model will then be forced with climatological data from the target regions, and compared with the analysis of the field data. Further, this model will be used to test the sensitivity of each species’ population dynamics to initial conditions, interaction with the timing of the spring bloom, and expected levels of climate variability. Finally, variability in the local population abundance of these two species due to responses to local climate versus population advection due to large-scale changes in physical transport will be addressed.

The results of the research will be important for understanding some of the basic processes that influence the seasonal production of a major group of plankton. This knowledge is critical for understanding the overall trophic impact of climate change on marine food webs within the CC.

Broader Impacts - The proposed research involves the direct participation of one postdoctoral student (Catherine Johnson, UNH). This research represents a first partnership between personnel from NOAA’s Pacific Fisheries Environmental Laboratory (PFEL) and the University of New Hampshire. The research will also receive support from and collaboration with three other entities, namely NOAA North West Science Center (through Bill Peterson), the University of Washington, School of Fisheries (Bruce Frost), and the Institute of Ocean Studies, Canada (Dave Mackas). Additionally, the work from this proposal will be closely linked to a separate proposal submitted by Schwing et al., (PFEL). The information gained from this work should prove valuable to fisheries management for small pelagics and other managed invertebrate species. The results of this research will also be served to the public through a web-based Live Access Server system, thus making it readily and broadly available.

NSF Award Summary

Calanoid copepods are key organisms in the California Current (CC) region, consuming primary and secondary production at high rates and serving as prey for larval, juvenile, and small pelagic fish, other invertebrates and certain seabirds. A critical period in the life of several calanoid species is their overwintering period, during which they leave the unproductive surface waters in mid-summer to fall and then ascend to the surface in the springtime, usually coincident with the spring bloom. However, the physical and biological cues that both initiate and terminate the dormant phase of several key copepod species within the CC are poorly known. The goal of this research is to test the hypothesis that the dormant phase of two major calanoid species, Calanus pacificus and Calanus marshallae, are in part controlled by changes in temperature and prey abundance. This hypothesis will be tested by two means. First, the existing data on relative stage abundance and vertical distribution of the two target species for four distinct locations along the west coast of North America will be compiled and compared to observational bio-physical datasets, many of which were collected as part of the GLOBEC NEP program. Second, an Individual-Based Model (IBM) for each of the two species will be developed, based on several different conceptual models of how temperature and prey availability control the dormancy response. This model will then be forced with climatological data and compared with the analysis of the field data. Further, this model will be used to test the sensitivity of each species' population dynamics to initial conditions, interaction with the timing of the spring bloom, and expected levels of climate variability. Finally, variability in the local population abundance of these two species due to responses to local climate versus population advection due to large-scale changes in physical transport will be addressed. The results of the research will be important for understanding some of the basic processes that influence the seasonal production of a major group of plankton. This knowledge is critical for understanding the overall trophic impact of climate change on marine food webs within the CC. This research involves a postdoctoral student and the information gained from this work should prove valuable to fisheries management for small pelagics and other managed invertebrate species. The results of this research will also be served to the public through a web-based Live Access Server system, thus making it readily and broadly available.

This page was last updated on March 14, 2007.

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Oregon State University
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