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Volume 66, Issue 12 p. 4391-4402
Article

At the mercy of the winds: The seasonal dynamics of floating and stranded seaweeds at mid-latitudes

Eva Rothäusler

Eva Rothäusler

Centro de Investigaciones Costeras—Universidad de Atacama (CIC–UDA), Copiapó, Chile

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Iván A. Hinojosa

Iván A. Hinojosa

Departamento de Ecología, Facultad de Ciencias, Universidad Católica de la Santísima Concepción, Concepción, Chile

Centro de Investigación en Biodiversidad y Ambientes sustentables (CIBAS), Concepción, Chile

Millennium Nucleus Ecology and Sustainable Management of Oceanic Island (ESMOI), Coquimbo, Chile

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Julio Moraga

Julio Moraga

Departamento de Biología Marina, Facultad de Ciencias del Mar, Universidad Católica del Norte, Coquimbo, Chile

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Matias Pizarro-Koch

Matias Pizarro-Koch

Millennium Nucleus Understanding Past Coastal Upwelling Systems and Environmental Local and Lasting Impacts (UPWELL), Agencia Nacional de Investigación y Desarrollo (ANID) Millennium Science Initiative, Coquimbo, Chile

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Marcel Ramos

Marcel Ramos

Millennium Nucleus Ecology and Sustainable Management of Oceanic Island (ESMOI), Coquimbo, Chile

Departamento de Biología Marina, Facultad de Ciencias del Mar, Universidad Católica del Norte, Coquimbo, Chile

Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Coquimbo, Chile

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Martin Thiel

Corresponding Author

Martin Thiel

Millennium Nucleus Ecology and Sustainable Management of Oceanic Island (ESMOI), Coquimbo, Chile

Departamento de Biología Marina, Facultad de Ciencias del Mar, Universidad Católica del Norte, Coquimbo, Chile

Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Coquimbo, Chile

Correspondence: [email protected]

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First published: 09 November 2021
Citations: 1
Associate editor: James J. Leichter

Abstract

Many seaweed species are particularly important for passive marine dispersal, yet relatively little is known about their floating and stranding dynamics. Here, we studied these dynamics for two kelp species over four consecutive years at mid-latitudes (30°S). Floating kelps were found during all seasons, but Macrocystis pyrifera was always more abundant than Durvillaea incurvata. Highest floating biomasses were reached during summer and fall, whereas considerable stranded biomasses on nearby shores were only observed during summer. The proportion of fragments among the floating kelps was high throughout the entire study period and highest for M. pyrifera during summer. At the same time, blades of M. pyrifera that floated in nearshore waters in summer had a high blade index and thus were intact (i.e., not yet compromised by unfavorable environmental conditions). These results suggest that during summer, floating kelps become quickly resupplied from benthic sources, which compensates their frequent losses due to degradation and stranding. During fall, biomasses of floating kelps remain high because of reduced losses. Interestingly, increased wind speed was a good predictor for the biomass accumulations of the two kelp species, although the floating biomass of M. pyrifera was additionally influenced by oceanographic fronts. Our findings suggest that at mid-latitudes the dynamics of floating seaweed stocks are dependent on the availability of benthic source populations (continuous throughout the year) and export due to degradation (high in summer/fall) and stranding (high in summer).