Marine Ecosystem Variations Over the North Pacific and Their Linkage to Large-Scale Climate Variability and Change

Abstract

In order to understand how North Pacific (NP) marine ecosystems have varied, 120 marine biological time series for both the western (29 time series) and eastern (91 time series) NP were analyzed with a Principal Component Analysis (PCA) for the period 1965-2006. This is the first attempt to conduct a multivariate analysis for a large number of marine biological data in the western and eastern NP combined. We used Monte-Carlo simulation to evaluate confidence levels of correlations and explained variance ratio of PCA modes while accounting for auto-correlation within the analyzed time series. All first mode principal components (PC1s), which are the time coefficients of the first PCA modes, calculated for the data in the whole, western, and eastern NP exhibit a long-term trend. The PC1s were associated with an overall increase of Alaskan and Japanese/Russian salmon, and decreases of groundfish across the basin. This mode was closely related to the warming of sea-surface temperature over the NP and over the global oceans, thereby suggesting that the strongest mode of the NP marine ecosystem was already influenced by global warming. The eastern NP PC2, characterized by multidecadal variability, was correlated positively with salmon and negatively with groundfish. On the other hand, the western NP PC2 exhibited slightly shorter timescale interdecadal variability than the eastern NP PC2 and was negatively correlated with zooplankton and two small pelagic fish time series around Japan. The eastern NP PC2 was most strongly related to the Pacific (inter-)Decadal Oscillation index, while the western NP PC2 was most closely related to the North Pacific Gyre Oscillation index. Consequently, the present analysis provides a new and unified view of climate change and marine ecosystem variations across the western and eastern NP. In particular, it is suggested that global warming has already substantially influenced the NP marine ecosystem, and that groundfish may suffer more than pelagic fish in response to future global warming.

Critical transitions and ecological resilience of large marine ecosystems in the Northwestern Pacific in response to global warming

“…This remarkable warming lays a foundation for the warming‐induced dynamics of LMEs. (3) Numerous studies on the Northwestern Pacific have proved the dominant roles of SST on variability in populations (e.g., Kuroda et al, 2020; Tian et al, 2013; Yatsu, 2019), communities (e.g., Ma et al, 2021; Tian et al, 2014; Tu et al, 2015), and ecosystems (e.g., Ma et al, 2020; Yati et al, 2020; Yatsu et al, 2013), which endorses the potential responses of LMEs to SST. (4) Our results provide evidence for the warming‐induced critical transitions according to Scheffer's theory (i.e., critical transition occurs at local maxima of SSTs), and the dominance shift from cold‐affinity species to warm‐affinity species also supports the driving effects of warming (also discussed in Section 4.2).…”

Toward Regional Marine Ecological Forecasting Using Global Climate Model Predictions From Subseasonal to Decadal Timescales: Bottlenecks and Recommendations

“…A classic example is the relation between the Pacific Decadal Oscillation (PDO) and Pacific salmon catches (Mantua et al, 1997), and that between the PDO and the Japanese sardine population (Yasuda et al, 1999). A more systematic approach using principal component analysis of a large number of marine ecosystem indicators reported that many species are influenced by climate variability and change in the North Pacific and adjacent seas (Hare and Mantua, 2000 ;Tian et al, 2006;Litzow and Mueter, 2014;Ma et al, 2019;Yati et al, 2020) and in the northeast Atlantic (Brunel and Boucher, 2007). Of course, such statistical analysis can only identify correlations, which do not necessarily mean causality, and the relationships may be nonstationary.…”

Influence of environmental and population factors on Prince William Sound herring spawning phenology

“…The Northeast Pacific has experienced a series of environmental and species-level regime shifts (Yati et al 2020). Due to fluctuations in herring biomass during the study period (1980−2019), we wanted to test the hypothesis of different biological regimes based on SSB and surplus production (described above).…”