Broad impacts of fine-scale dynamics on seascape structure from zooplankton to seabirds

Bertrand, Arnaud; Grados, Daniel; Colas, François; Bertrand, Sophie; Capet, Xavier; Chaigneau, Alexis; Vargas, Gary; Mousseigne, Alexandre; Fablet, Ronan

doi:10.1038/ncomms6239

Cited by 99 publications

(87 citation statements)

References 51 publications

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“…During a great part of the record (from ~1905 to 1970), there was an efficient upwelling of cold and nutrient‐rich waters probably in combination with a shallower thermocline and larger zooplankton; characteristics that are favorable for the development of anchovy (Bertrand et al., ). A shallow‐oxygenated habitat, promoted by the increase in upwelling, concentrates the prey near the surface enhancing anchovy foraging and leading to a reproductive advantage over sardine (Bertrand et al., , ). On the opposite, anchovy are less abundant when the productivity is very low (Figure g) and/or when the horizontal extent of the cold coastal waters is reduced and the oxycline deepen as was observed from the 1970s–mid‐1990s (Figure ; Bertrand et al., ).…”

Section: Discussionmentioning

confidence: 99%

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

Salvatteci

Field

Gutiérrez

et al. 2017

Global Change Biology

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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.

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Section: Discussionmentioning

confidence: 99%

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

Salvatteci

Field

Gutiérrez

et al. 2017

Global Change Biology

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“…In the Humboldt Current System, Bertrand et al . () showed that physical structures, such as internal waves, induce local deformations in the vertical location of the oxycline, where zooplankton, fish, Peruvian Boobies and Guanay Cormorants aggregate.…”

Section: Discussionmentioning

confidence: 99%

Predictive modelling of habitat selection by marine predators with respect to the abundance and depth distribution of pelagic prey

Boyd

Castillo

Hunt

et al. 2015

Journal of Animal Ecology

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Summary 1.Understanding the ecological processes that underpin species distribution patterns is a fundamental goal in spatial ecology. However, developing predictive models of habitat use is challenging for species that forage in marine environments, as both predators and prey are often highly mobile and difficult to monitor. Consequently, few studies have developed resource selection functions for marine predators based directly on the abundance and distribution of their prey. 2. We analysed contemporaneous data on the diving locations of two seabird species, the shallow-diving Peruvian Booby (Sula variegata) and deeper diving Guanay Cormorant (Phalacrocorax bougainvilliorum), and the abundance and depth distribution of their main prey, Peruvian anchoveta (Engraulis ringens). Based on this unique data set, we developed resource selection functions to test the hypothesis that the probability of seabird diving behaviour at a given location is a function of the relative abundance of prey in the upper water column. 3. For both species, we show that the probability of diving behaviour is mostly explained by the distribution of prey at shallow depths. While the probability of diving behaviour increases sharply with prey abundance at relatively low levels of abundance, support for including abundance in addition to the depth distribution of prey is weak, suggesting that prey abundance was not a major factor determining the location of diving behaviour during the study period. 4. The study thus highlights the importance of the depth distribution of prey for two species of seabird with different diving capabilities. The results complement previous research that points towards the importance of oceanographic processes that enhance the accessibility of prey to seabirds. The implications are that locations where prey is predictably found at accessible depths may be more important for surface foragers, such as seabirds, than locations where prey is predictably abundant. 5. Analysis of the relative importance of abundance and accessibility is essential for the design and evaluation of effective management responses to reduced prey availability for seabirds and other top predators in marine systems.

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“…, Bertrand et al. ). We hypothesize that the persistence of trophic hotspots in upwelling ecosystems is the result of physical forces that affect enrichment (nutrients and primary production), concentration, and retention of lower trophic levels (Bakun ).…”

Section: Introductionmentioning

confidence: 98%

Persistence of trophic hotspots and relation to human impacts within an upwelling marine ecosystem

Santora

Sydeman

Schroeder

et al. 2017

Ecological Applications

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Human impacts (e.g., fishing, pollution, and shipping) on pelagic ecosystems are increasing, causing concerns about stresses on marine food webs. Maintaining predator-prey relationships through protection of pelagic hotspots is crucial for conservation and management of living marine resources. Biotic components of pelagic, plankton-based, ecosystems exhibit high variability in abundance in time and space (i.e., extreme patchiness), requiring investigation of persistence of abundance across trophic levels to resolve trophic hotspots. Using a 26-yr record of indicators for primary production, secondary (zooplankton and larval fish), and tertiary (seabirds) consumers, we show distributions of trophic hotspots in the southern California Current Ecosystem result from interactions between a strong upwelling center and a productive retention zone with enhanced nutrients, which concentrate prey and predators across multiple trophic levels. Trophic hotspots also overlap with human impacts, including fisheries extraction of coastal pelagic and groundfish species, as well as intense commercial shipping traffic. Spatial overlap of trophic hotspots with fisheries and shipping increases vulnerability of the ecosystem to localized depletion of forage fish, ship strikes on marine mammals, and pollution. This study represents a critical step toward resolving pelagic areas of high conservation interest for planktonic ecosystems and may serve as a model for other ocean regions where ecosystem-based management and marine spatial planning of pelagic ecosystems is warranted.

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Broad impacts of fine-scale dynamics on seascape structure from zooplankton to seabirds

Cited by 99 publications

References 51 publications

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

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

Predictive modelling of habitat selection by marine predators with respect to the abundance and depth distribution of pelagic prey

Persistence of trophic hotspots and relation to human impacts within an upwelling marine ecosystem

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