Analysis of Zooplankton Population Fluctuations in the Strait of Georgia, British Columbia

Abstract

Canonical correlation, cluster, multiple regression, factor, and principal component analyses were used to examine zooplankton and hydrographic data over the period of unusual fluctuations in the overwintering population sizes of Calanus plumchrus, C. marshallae, and C. pacificus in the Strait of Georgia. Additional hydrographic data were examined for relationships between physical and biological data 3 and 6 mo out of phase. Analysis indicates a recent subtle temperature and salinity shift of uncertain biological significance. Canonical correlation and principal component analyses suggest that 15% of the variance in the zooplankton is related to a temporal trend paralleling that seen in the physical characteristics of the environment.Based on the factor analysis, C. plumchrus, Pseudocalanus minutas, Acartia longiremus, Sagitta elegans, Euphausia pacifica, Limacina spp, and Oithona spinirostris are suggested as "key" species for future zooplankton monitoring programs. Statistically supported species selection can reduce the time and expense of sorting zooplankton samples without an equivalent reduction of information yield. Key words: zooplankton, populations, Calanus, statistical analysis, temporal trends