MEPS 385:151-163 (2009)  -  DOI: https://doi.org/10.3354/meps08042

Thriving and declining: climate variability shaping life-history and population persistence of Mesodesma donacium in the Humboldt Upwelling System

José M. Riascos1,2,*, Daniel Carstensen2, Jürgen Laudien2, Wolf E. Arntz2, Marcelo E. Oliva1, Andreas Güntner3, Olaf Heilmayer2,4

1Universidad de Antofagasta, Instituto de Investigaciones Oceanológicas, Avenida Angamos 601 Antofagasta, Chile
2Alfred Wegener Institute for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany
3Helmholtz Centre Postdam, GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany
4German Aerospace Center (DLR), Heinrich Konen-Str. 1, 53227 Bonn, Germany

ABSTRACT: Large-scale environmental patterns in the Humboldt Current System (HCS) show major changes during strong El Niño episodes, leading to the mass mortality of dominant species in coastal ecosystems. Here we explore how these changes affect the life-history traits of the surf clam Mesodesma donacium. Growth and mortality rates under normal temperature and salinity were compared to those under anomalous (El Niño) higher temperature and reduced salinity. Moreover, the reproductive spatial–temporal patterns along the distribution range were studied, and their relationship to large-scale environmental variability was assessed. M. donacium is highly sensitive to temperature changes, supporting the hypothesis of temperature as the key factor leading to mass mortality events of this clam in northern populations. In contrast, this species, particularly juveniles, was remarkably tolerant to low salinity, which may be related to submarine groundwater discharge in Hornitos, northern Chile. The enhanced osmotic tolerance by juveniles may represent an adaptation of early life stages allowing settlement in vacant areas at outlets of estuarine areas. The strong seasonality in freshwater input and in upwelling strength seems to be linked to the spatial and temporal patterns in the reproductive cycle. Owing to its origin and thermal sensitivity, the expansion and dominance of M. donacium from the Pliocene/Pleistocene transition until the present seem closely linked to the establishment and development of the cold HCS. Therefore, the recurrence of warming events (particularly El Niño since at least the Holocene) has submitted this cold-water species to a continuous local extinction–recolonization process.


KEY WORDS: El Niño · Fresh water input · Geographic distribution · Reproductive cycle · Sandy beach ecology · Submarine groundwater discharge · Macroecology


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Cite this article as: Riascos JM, Carstensen D, Laudien J, Arntz WE, Oliva ME, Güntner A, Heilmayer O (2009) Thriving and declining: climate variability shaping life-history and population persistence of Mesodesma donacium in the Humboldt Upwelling System. Mar Ecol Prog Ser 385:151-163. https://doi.org/10.3354/meps08042

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