Multifarious anchovy and sardine regimes in the Humboldt Current System during the last 150 years

Abstract

The Humboldt Current System (HCS) has the highest production of forage fish in the world, although it is highly variable and the future of the primary component, anchovy, is uncertain in the context of global warming. Paradigms based on late 20th century observations suggest that large-scale forcing controls decadal-scale fluctuations of anchovy and sardine across different boundary currents of the Pacific. We develop records of anchovy and sardine fluctuations since 1860 AD using fish scales from multiple sites containing laminated sediments and compare them with Pacific basin-scale and regional indices of ocean climate variability. Our records reveal two main anchovy and sardine phases with a timescale that is not consistent with previously proposed periodicities. Rather, the regime shifts in the HCS are related to 3D habitat changes driven by changes in upwelling intensity from both regional and large-scale forcing. Moreover, we show that a long-term increase in coastal upwelling translates via a bottom-up mechanism to top predators suggesting that the warming climate, at least up to the start of the 21st century, was favorable for fishery productivity in the HCS.

Multidecadal Changes in Marine Subsurface Oxygenation Off Central Peru During the Last ca. 170 Years

“…Muddy laminated areas are found between Huacho and Callao (11 -12 • S; Reinhardt et al, 2002), but sedimentary records retrieved in the OMZ core off Pisco (14 • S) are better laminated (Gutiérrez et al, 2006;Salvatteci et al, 2014a). 210 Pb sedimentation rates vary from 0.4 mm/y to 4 mm/y in the shelf and slope (Levin et al, 2002;Gutiérrez et al, 2009;Salvatteci et al, 2018). Figure 1B shows the main three equatorial currents arriving the Eastern Tropical Pacific.…”

“…The methodology and data for the geochemical (Mo and δ 15 N) and organic concentrations [total organic carbon (TOC), biogenic silica] for B-13 and B-6 are shown in Gutiérrez et al (2009). Data for B-14 (TOC, biogenic silica, Mo, Re and δ 15 N) were published in Salvatteci et al (2014bSalvatteci et al ( , 2018. Subsampling for geochemical proxies in B-13 and B-6 was done every centimeter for trace elements and every two centimeters for TOC, biogenic silica and δ 15 N (Gutiérrez et al, 2009).…”

Deglacial to Holocene Ocean Temperatures in the Humboldt Current System as Indicated by Alkenone Paleothermometry

“…Data of sea-level pressure and wind stress for the last decades suggest an overall trend toward a stronger, La Niña-like Walker Circulation (England et al, 2014;L'Heureux et al, 2013). While during the Mid-Holocene, the productivity was low in the HCS perhaps due to the upwelling of subsurface waters containing low nutrients; the last century is characterized by high marine productivity (Gutierrez et al, 2011;Salvatteci et al, 2018) likely due to a favorable combination of a strong and nutrient-rich oxygen minimum zone (Salvatteci, Gutierrez, et al, 2014), high summer-spring water column stratification (Salvatteci et al, 2018), and strong winds (Briceño-Zuluaga et al, 2016). While the present study provides important insight in the context of climate change, the impact of future global warming on the biological productivity in the HCS remains uncertain and should be treated as such in future management strategies (Salvatteci et al, 2018).…”

Counterintuitive effects of global warming‐induced wind patterns on primary production in the Northern Humboldt Current System

“…Furthermore, Salvatteci et al. () suggest that a long‐term increase in coastal upwelling due to the warming climate, at least up to the start of the 21st century, is favorable for fisheries productivity in the HCS. Our results show a moderate increase in primary production and suggest that its spatiotemporal variability is a result of a delicate interplay between nutrient availability and nutrient use efficiency.…”

“…However, this moderate primary production (which would in turn sustain zooplankton and upper trophic level communities) does not necessarily lead to smaller fish production, according to Bakun and Weeks (2008), who emphasizes the notion that in the ocean, "food heaven" generally coincides with "predation hell", because fish production usually depends more on recruitment success than on food availability. Furthermore, Salvatteci et al (2018) suggest that a long-term increase in coastal upwelling due to the warming climate, at least up to the start of the 21st century, is favorable for fisheries productivity in the HCS. Our results show a moderate increase in primary production and suggest that its spatiotemporal variability is a result of a delicate interplay between nutrient availability and nutrient use efficiency.…”