Rockfish response to low-frequency ocean climate change as revealed by the diet of a marine bird over multiple time scales

Abstract

We examined the effects of ocean climate variability on juvenile rockfish Sebastes spp. from in the central California Current by examining the diet of a local marine bird, the common murre Uria aalge, on multiple temporal scales. Responses to higher-frequency climate change (interannual El Niño and La Niña events) were strong, with declines in rockfish take in warmwater years. Responses to low-frequency climate events (e.g. shifts of the Pacific Decadal Oscillation, PDO) were less obvious. Inter-annual patterns showed no response to the 1976-1977 regime shift to warmer PDO conditions. Instead, rockfish use declined beginning in 1989, corresponding to another suggested regime change, then rebounded shortly after the hypothesized return to a cool phase of the PDO in the late 1990s. Intra-annual diet patterns, however, revealed changes in rockfish use well before 1989. These signals indicate that declines may have corresponded to the 1976-1977 regime shift but were lagged, possibly due to the long lifespan and intermittent recruitment of rockfish. This interpretation is supported by local upwelling patterns that show a lagged correlation between upwelling and juvenile rockfish abundance in the marine bird diet.

Trade-offs in prey quality and quantity revealed through the behavioral compensation of breeding seabirds

“…Wells et al (2008) found that the integration of several physical parameters, both atmospheric and oceanic, could be related directly and indirectly (that is, through trophic pathways) to seabird production, including murres, in the California Current System. In a study comparing oceanographic forcing to the proportion of rockfish in murre chick diets in California, Miller & Sydeman (2004) found that strong forcing events could be linked to some annual diet shifts, but the more subtle effects of PDO regime shifts were only apparent in an analysis of seasonal trends. Definite causal relationships between murre chick diet and bottom-up forcing may be apparent when smaller time and space scales are examined, such as the link between 3 to 5 d upwelling events and lanternfish appearance in Tatoosh Island murre chick diets reported by Parrish & Zador (2003).…”

“…Studies in which shifts in the relative abundance of different prey taxa result in shifts in seabird nestling diet are common (e.g. Bryant et al 1999, Gaston et al 2003, Miller & Sydeman 2004, Hipfner 2009), but studies that focus on prey quality are less common. One exception is a study by Davoren & Montevecchi (2003), who reported that an increase in the proportion of immature, and therefore smaller, capelin Mallotus villosus negatively affected the condition of common murre Uria aalge chicks in Newfoundland.…”

“…The island sits at the mouth of the Strait of Juan de Fuca, a region with a complex prey field (Brodeur et al 2005, Emmett et al 2006) and high variability in ocean productivity (Hickey 1998, Hickey & Banas 2003. Although common murres in other systems appear to rely primarily on single (Davoren & Montevecchi 2003) or dual (Miller & Sydeman 2004, Wanless et al 2005) prey species, in the northern California Current murres are catholic foragers, regularly returning several prey species to their chicks (Parrish & Zador 2003). This system provided adult murres ample opportunities for utilizing different provisioning strategies under a range of environmental conditions.…”

Dietary changes of Mediterranean ShagsPhalacrocorax aristotelis desmarestiibetween the breeding and post-breeding seasons in the upper Adriatic Sea

“…They have therefore been used as reliable indicators of changes in fish populations (Hatch & Sanger 1992, Montevecchi 1993, Furness & Camphuysen 1997, Barrett 2002. Changes in a variety of seabird foraging parameters have been successfully used to detect alterations in prey age-class structure (Davoren & Montevecchi 2003), responses of prey populations to climate change (Miller & Sydeman 2004), and variations in the energetic value of prey (Wanless et al 2005). Furthermore, seabirds' dietary adjustments may indicate shifts in pelagic food webs (Montevecchi & Myers 1996).…”

Influence of Basin‐ and Local‐Scale Environmental Conditions on Nearshore Production in the Northeast Pacific Ocean

“…Time lags must be considered when linking predator production with environmental conditions through trophic interactions (sensu Post 2004), especially when predators are limited by the availability of prey that are at least 1 year old and when prey abundance is determined by conditions experienced early in life history (Miller and Sydeman 2004;Frederiksen et al 2006). Analyses spanning multiple seasons at plausible biological time lags are helpful in identifying whether conditions that are present during a specific window of months or during the transition from one seasonal climate state to another are particularly important to biological function.…”