Interdecadal variability in the Gulf of Maine zooplankton community, with potential impacts on fish recruitment

Abstract

We used principal component analysis (PCA) to explore interannual changes in a time-series lasting more than 40 years of zooplankton abundance from NOAA's Continuous Plankton Recorder (CPR) survey. This analysis identified a complex of taxa, including Centropages typicus, Oithona spp., Pseudocalanus spp., and Metridia lucens that followed a common pattern of interdecadal variability characterized by a dramatic increase in these taxa around 1990, followed by a rapid decline in 2002. All of these taxa showed a large proportional increase in winter abundance between the 1980s and 1990s. These changes could be driven by increased primary productivity during winter, caused by a large-scale freshening of the Northwest Atlantic Shelf. In addition to the “community shift” mode, the analysis found a strong mode of interannual variability attributed to previously described changes in the abundance of late-stage Calanus finmarchicus. To explore the impact of these modes on higher trophic levels, we correlated the zooplankton modes with recruitment time-series from 12 fish stocks from the Gulf of Maine region. Several significant correlations were found, suggesting that the changes in the zooplankton modes may reflect broad changes in the Gulf of Maine ecosystem.

Spring bloom dynamics and zooplankton biomass response on the US Northeast Continental Shelf

“…The medium-sized luminescent copepod M. lucens was significantly correlated to biomass trends throughout the northern half of the ecosystem. Its maximum abundance is measured in the Gulf of Maine, where increased primary productivity in winter has produced high abundance levels (Pershing et al, 2005). Though under-sampled in our nets, the interannual variability of the cyclopoid copepod Oithona spp.…”

Arctic Climate Change and Its Impacts on the Ecology of the North Atlantic

“…The increased stratification and associated phytoplankton production coincided with a reorganization of the zooplankton assemblage, with populations of smaller, shelf-associated copepods, like Centropages typicus, Metridia lucens, Oithona spp., and Pseudocalanus spp., increasing significantly in abundance (Fig. 4c) (Durbin et al 2003, Pershing et al 2005. Early copepodid stages of Calanus finmarchicus also increased in abundance with these smaller species; however, later copepodid stages of this more oceanic species declined in abundance (Fig.…”

“…4d). Pershing et al (2005) have suggested that increased size-selective predation by herring may have been behind these paradoxical observations for C. finmarchicus. The largest increases in small copepod abundance were observed during late autumn/early winter, a change associated with the enhanced autumn phytoplankton blooms (Durbin et al 2003).…”

Recent Arctic Climate Change and Its Remote Forcing of Northwest Atlantic Shelf Ecosystems

“…The autumn phytoplankton color index is the mean autumn color index anomaly calculated from gulf of Maine continuous plankton recorder (goM cpr) survey data (greene and pershing, 2007). The Small copepod abundance index is the first mode from a pca of annual small copepod abundance anomalies calculated from goM cpr survey data (Technical note 6;pershing et al, 2005). The C. finmarchicus abundance index is the mean abundance anomaly calculated each year from goM cpr survey data; it is calculated separately for early juveniles (copepodites 1-4) and late stages (copepodite 5 and adults) of this species (pershing et al, 2005).…”

“…The C. finmarchicus abundance index is the mean abundance anomaly calculated each year from goM cpr survey data; it is calculated separately for early juveniles (copepodites 1-4) and late stages (copepodite 5 and adults) of this species (pershing et al, 2005). Size-selective predation by herring on the larger and older stages of C. finmarchicus may explain this apparent paradox (Pershing et al, 2005).…”