Is there enough zooplankton to feed forage fish populations off Peru? An acoustic (positive) answer

Ballón, Michael; Bertrand, Arnaud; Lebourges‐Dhaussy, Anne; Gutiérrez, Mariano; Ayón, Patricia; Grados, Daniel; Gerlotto, François

doi:10.1016/j.pocean.2011.03.001

Cited by 75 publications

(80 citation statements)

References 74 publications

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“…The macro-zooplankton is a fundamental dietary component for fish species, such as the Peruvian anchovy Engraulis ringens. The Humboldt System sustains a significant biomass of macro-zooplankton which usually migrates within a day from the surface to about 300 m depth playing an essential ecological role (Ballón et al 2011). This is highly sensitive to climate oscillations and strongly depends on upwelled water (Mackas et al 2006).…”

Section: Considerations For Marine Life and Fishery Productivitymentioning

confidence: 99%

The future of coastal upwelling in the Humboldt current from model projections

Oyarzún

Brierley

2018

Clim Dyn

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The Humboldt coastal upwelling system in the eastern South Pacific ocean is one of the most productive marine ecosystems in the world. A weakening of the upwelling activity could lead to severe ecological impacts. As coastal upwelling in eastern boundary systems is mainly driven by wind stress, most studies so far have analysed wind patterns change through the 20th and 21st Centuries in order to understand and project the phenomenon under specific forcing scenarios. Mixed results have been reported, and analyses from General Circulation Models have suggested even contradictory trends of wind stress for the Humboldt system. In this study, we analyse the ocean upwelling directly in 13 models contributing to phase 5 of the Coupled Model Intercomparison Project (CMIP5) in both the historical simulations and an extreme climate change scenario (RCP8.5). The upwelling is represented by the upward ocean mass flux, a newly-included variable that represents the vertical water transport. Additionally, wind stress, ocean stratification, Ekman layer depth and thermocline depth were also analysed to explore their interactions with coastal upwelling throughout the period studied. The seasonal cycle of coastal upwelling differs between the Northern and Southern Humboldt areas. At lower latitudes, the upwelling season spans most of the autumn, winter and spring. However, in the Southern Humboldt area the upwelling season takes place in spring and the summertime with downwelling activity in winter. This persists throughout the Historical and RCP8.5 simulations. For both the Northern and Southern Humboldt areas an increasing wind stress is projected. However, different trends of upwelling intensity are observed away from the sea surface. Whereas wind stress will continue controlling the decadal variability of coastal upwelling on the whole ocean column analysed (surface to 300 m depth), an increasing disconnect with upwelling intensity is projected below 100 m depth throughout the 21st Century. This relates to an intensification of ocean stratification under global warming as shown by the sea water temperature profiles. Additionally, a divergence between the Ekman layer and thermocline depths is also evidenced. Given the interaction of upwelled nutrients and microscopic organisms essential for fish growth, a potential decline of coastal upwelling at depth could lead to unknown ecological and socio-economical effects.

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Section: Considerations For Marine Life and Fishery Productivitymentioning

confidence: 99%

The future of coastal upwelling in the Humboldt current from model projections

Oyarzún

Brierley

2018

Clim Dyn

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“…The shelf break appears thus as an important biogeographical barrier affecting species distribution (e.g. Ballón et al, 2011) and therefore the fish diet.…”

Section: Spatial Patternsmentioning

confidence: 99%

“…This paradox can be explained by the fact that P. monodon and zoea larvae are prey easy to handle and, as part of the epipelagic community, they are concentrated in dense patches within a thin surface layer above the oxycline . Additionally, they are accessible during the complete diel cycle when most euphausiidae perform diel vertical migration and are inaccessible during the day (Ballón et al, 2011). Furthermore, P. monodon energy content is high.…”

Section: Long Term Trend and The Euphausiidae Paradoxmentioning

confidence: 99%

Diet diversity of jack and chub mackerels and ecosystem changes in the northern Humboldt Current system: A long-term study

Alegre

Bertrand

Espino

et al. 2015

Progress in Oceanography

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“…We did not convert larval fish density to carbon biomass, as we had no adequate information about the length distribution and the weight-length relationship of larval fish, which are necessary for the conversion. The zooplankton settled volume was determined using the displacement method (Ballón et al 2011). To exclude carnivorous zooplankton from the analyses, the samples were digitized with the ZooScan integrated system, and the scanned images were manually classified to calculate the volume percentage of chaetognaths and jellyfishes (Ye et al 2011;Chang et al 2012;García-Comas et al 2013).…”

Section: Sample Collection and Data Treatmentmentioning

confidence: 99%

Trophic structure of the pelagic food web in the East China Sea

et al. 2015

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Background: Trophic structure and trophic transfer efficiency are among the most fundamental characteristics of an ecosystem. They characterize the transfer of nutrient and energy and are crucial in estimating the yield of harvestable biomass. In this study, we investigated the regulation of trophic structure (phytoplankton, zooplankton, and larval fish abundance) and biomass ratio of zooplankton to phytoplankton (as an indicator of transfer efficiency) in the East China Sea, one of the largest marginal seas in the world and an important fishing ground.

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Is there enough zooplankton to feed forage fish populations off Peru? An acoustic (positive) answer

Cited by 75 publications

References 74 publications

The future of coastal upwelling in the Humboldt current from model projections

The future of coastal upwelling in the Humboldt current from model projections

Diet diversity of jack and chub mackerels and ecosystem changes in the northern Humboldt Current system: A long-term study

Trophic structure of the pelagic food web in the East China Sea

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