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Temporal variation in pelagic food chain length in response to environmental change

TitleTemporal variation in pelagic food chain length in response to environmental change
Publication TypeJournal Article
Year of Publication2017
AuthorsRuiz-Cooley RI, Gerrodette T., Fiedler PC, Chivers SJ, Danil K., Ballance LT
JournalScience Advances
Date Published2017/10
Type of ArticleArticle
ISBN Number2375-2548
Accession NumberWOS:000417998700023
Keywordsamino-acids; california current system; changes; climate; delta-n-15 values; ecosystem; el-nino; long-term; nitrogen isotopic composition; southern california; tursiops-truncatus

Climate variability alters nitrogen cycling, primary productivity, and dissolved oxygen concentration in marine ecosystems. We examined the role of this variability (as measured by six variables) on food chain length (FCL) in the California Current (CC) by reconstructing a time series of amino acid-specific delta N-15 values derived from common dolphins, an apex pelagic predator, and using two FCL proxies. Strong declines in FCL were observed after the 1997-1999 El Nino Southern Oscillation (ENSO) event. Bayesian models revealed longer FCLs under intermediate conditions for surface temperature, chlorophyll concentration, multivariate ENSO index, and total plankton volume but not for hypoxic depth and nitrate concentration. Our results challenge the prevalent paradigm that suggested long-term stability in the food web structure in the CC and, instead, reveal that pelagic food webs respond strongly to disturbances associated with ENSO events, local oceanography, and ongoing changes in climate.

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