@article{fdi:010061770,
  title = {{A}nalysing changes in the southern {H}umboldt ecosystem for the period 1970-2004 by means of dynamic food web modelling},
  author = {{N}eira, {S}. and {M}oloney, {C}. and {C}hristensen, {V}. and {C}ury, {P}hilippe and {S}hannon, {L}. and {A}rancibia, {H}.},
  editor = {},
  language = {{ENG}},
  abstract = {{A} 22-group {E}copath model representing the southern {H}umboldt ({SH}) upwelling system in the year 1970 is constructed. {T}he model is projected forward in time and fitted to available time series of relative biomass, catch and fishing mortality for the main fishery resources. {T}he time series cover the period 1970 to 2004 and the fitting is conducted using the {E}copath with {E}cosim ({E}w{E}) software version 5.1. {T}he aim is to explore the relative importance of internal (trophic control) and external (fishing, physical variability) forcing on the dynamics of commercial stocks and the {S}outhern {C}hilean food web. {W}ide decadal oscillations are observed in the biomass of commercial stocks during the analyzed period. {F}ishing mortality explains 21% of the variability in the time series, whereas vulnerability (v) parameters estimated using {E}w{E} explain an additional 20%. {W}hen a function affecting primary production ({PP}) is calculated by {E}cosim to minimize the sum of squares of the time series, a further 28% of variability is explained. {T}he best fit is obtained by using the fishing mortality time series and by searching for the best combination of v parameters and the {PP} function simultaneously, accounting for 69% of total variability in the time series. {T}he {PP} function obtained from the best fit significantly correlates with independent time series of an upwelling index ({UI}; rho = 0.47, p<0.05) and sea surface temperature ({SST}; rho = -0.45, p<0.05), representing environmental conditions in the study area during the same period of time. {T}hese results suggest that the {SH} ecosystem experienced at least two different environmentally distinct periods in the last three decades: (i) from 1970 to 1985 a relatively warm period with low levels of upwelling and {PP}, and (ii) from 1985 to 2004 a relatively cold period with increased upwelling and {PP}. {T}his environmental variability can explain some of the changes in the food webs. {F}ishing (catch rate) and the environment (bottom-up anomaly in {PP}) appear to have affected the {SH} both at the stock and at the food web level between 1970 and 2004. {T}he vulnerability setting indicates that the effects of external forcing factors may have been mediated by trophic controls operating in the food web.},
  keywords = {{E}copath with {E}cosim ; {F}ishing patterns ; {P}hysical forcing ; {R}egime shifts ; {S}outhern {H}umboldt ; {T}rophic controls ; {CHILI} ; {PACIFIQUE}},
  booktitle = {},
  journal = {{E}cological {M}odelling},
  volume = {274},
  numero = {},
  pages = {41--49},
  ISSN = {0304-3800},
  year = {2014},
  DOI = {10.1016/j.ecolmodel.2013.09.022},
  URL = {https://www.documentation.ird.fr/hor/fdi:010061770},
}