@article{fdi:010053397,
  title = {{L}ong-term changes in zooplankton size distribution in the {P}eruvian {H}umboldt {C}urrent {S}ystem : conditions favouring sardine or anchovy},
  author = {{A}yon, {P}. and {S}wartzman, {G}. and {E}spinoza, {P}. and {B}ertrand, {A}rnaud},
  editor = {},
  language = {{ENG}},
  abstract = {{C}hanges in the size distribution of zooplankton in the {H}umboldt {C}urrent {S}ystem have been hypothesized to underlie observed changes in sardine and anchovy populations, the dominant pelagic fish species. {T}o examine this hypothesis, the size distribution of over 15 000 zooplankton data samples collected since the 1960s was qualitatively determined. {D}ominance of each size group of zooplankton (small, medium and large) and of euphausiids was modelled using generalized additive models as a function of year, latitude, time of day, distance from the 200 m isobath (a surrogate for on-shelf versus off-shelf), sea surface temperature and salinity. {T}he temporal (yr) pattern for euphausiid dominance was highly cross-correlated (i.e. was in phase) with the time series for estimated biomass of anchovy, and small zooplankton dominance with that for estimated sardine biomass. {T}his supports the focal hypothesis based on feeding-energetic experiments, which showed energetic advantages to sardine filter feeding on smaller zooplankton and to anchovy bite feeding on larger copepods and euphausiids. {A}lthough euphausiids predominate offshore from the shelf break, anchovy biomass is generally highest on the shelf, suggesting a possible mismatch between anchovy feeding and euphausiid dominance. {H}owever, evidence concerning the offshore expansion of the anchovy range in cooler conditions, where both anchovy and euphausiids predominate, somewhat alleviates this apparent contradiction. {A} strong diel component to euphausiids and large zooplankton indicated diel migration for these zooplankton groups. {T}hat anchovy will preferentially eat euphausiids when they are more available (i.e. during the night and offshore) is supported by anchovy diet data.},
  keywords = {{A}nchovy ; {S}ardine ; {A}bundance ; {Z}ooplankton size dominance ; {F}eeding energetics ; {E}uphausiids ; {H}umboldt {C}urrent {S}ystem ; {PACIFIQUE}},
  booktitle = {},
  journal = {{M}arine {E}cology. {P}rogress {S}eries},
  volume = {422},
  numero = {},
  pages = {211--222},
  ISSN = {0171-8630},
  year = {2011},
  DOI = {10.3354/meps08918},
  URL = {https://www.documentation.ird.fr/hor/fdi:010053397},
}