Long-term Bering Sea environmental variability revealed by a centennial-length biochronology of Pacific ocean perch Sebastes alutus

Abstract

The productivity and functioning of Bering Sea marine ecosystems are tightly coupled to decadal-scale environmental variability, as exemplified by the profound changes in community composition that followed the 1976-1977 shift from a cool to a warm climate regime. Longer-term ecosystem dynamics, including the extent to which this regime shift was exceptional in the context of the past century, remain poorly described due to a lack of multi-decadal biological time series. To explore the impact of decadal regime shifts on higher trophic levels, we applied dendrochronology (tree-ring science) techniques to the otolith growth-increment widths of Pacific ocean perch Sebastes alutus (POP) collected from the continental slope of the eastern Bering Sea. After crossdating, 2 chronology development techniques were applied: (1) a regional curve standardization (RCS) approach designed to retain as much low-frequency variability as possible, and (2) an individual-detrending approach that maximized interannual synchrony among samples. Both chronologies spanned the years 1919-2006 and were significantly (p < 0.001) and positively correlated with sea surface temperature (March-December). The RCS chronology showed a transition from relatively slow to fast growth after 1976-1977. In both chronologies, the highest observed growth values immediately followed the regime shift, suggesting that this event had a critical and lasting impact on growth of POP. This growth pulse was, however, not shared by a previously published yellowfin sole Limanda aspera chronology (1969-2006) from the eastern Bering Sea shelf, indicating species- or site-specific responses. Ultimately, these chronologies provide a long-term perspective and underscore the susceptibility of fish growth to extreme low-frequency events.