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Marine Ecology Progress Series

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MEPS 561:31-50 (2016)  -  DOI:

Seasonal benthic patterns in a glacial Patagonian fjord: the role of suspended sediment and terrestrial organic matter

Eduardo Quiroga1,2,*, Paula Ortiz3,4, Rodrigo González-Saldías2,5,6, Brian Reid3, Fabián J. Tapia2,6, Iván Pérez-Santos2,7, Lorena Rebolledo2,8,9, Rodrigo Mansilla2, Carlos Pineda4, Ilia Cari4, Nicole Salinas1, Américo Montiel10, Dieter Gerdes11

1Pontificia Universidad Católica de Valparaíso (PUCV), Escuela de Ciencias del Mar, Valparaíso, Chile
2COPAS Sur-Austral, Universidad de Concepción, Concepción, Chile
3Centro de Investigación en Ecosistemas de la Patagonia (CIEP), Coyhaique, Chile
4Programa de Magister en Oceanografía, Escuela de Ciencias del Mar, Pontificia Universidad Católica de Valparaíso (PUCV), Valparaíso, Chile
5Unidad de Biotecnología Marina, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Chile
6Departamento de Oceanografía, Universidad de Concepción, Chile
7Centro I-Mar, Universidad de Los Lagos, Puerto Montt, Chile
8Instituto Antártico Chileno (INACH), Punta Arenas, Chile
9Centro FONDAP de Investigación de Ecosistemas de Altas Latitudes (IDEAL), Universidad Austral de Chile, Valdivia, Chile
10Instituto de la Patagonia, Universidad de Magallanes, Punta Arenas, Chile
11Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, 27568 Bremerhaven, Germany
*Corresponding author:

ABSTRACT: Complex marine-terrestrial interactions characterize Chilean fjords, where benthic communities influence the distribution of organic matter (OM). We examined spatial and seasonal changes in the hydrography, sediment conditions and soft-bottom macrobenthic, meiobenthic, and total microbial biomass in a glacial Patagonian fjord (Martinez Channel, Chile). The transport of a high load of glacial mineral and particulate OM to the fjord in the austral summer coincided with low total live benthic biomass. Multivariate analysis evidenced temporal-related macrofaunal groups influenced by the different environments produced by the advection of sediment transport and terrestrial OM from the Baker River, Chile. The relationships between density/biomass and respiration versus body size varied considerably with distance from major riverine inputs, but the slopes of density size spectra and normalized biomass size spectra were less negative in summer than in winter. Occasional large-scale advective processes in the water column affected sediment conditions and removed surface macrofauna, influencing the slope and intercept of the regression models. In the outer fjord, lateral advection and subsequent sedimentation of terrestrial OM contributed a significant fraction to total OM sediments (<14.76%). Stable carbon isotopes measured in benthic organisms suggest that benthic communities in the inner fjord may assimilate a significant fraction of terrestrial OM via heterotrophic bacteria in contrast to the minor input of terrestrial OM in the outer fjord.

KEY WORDS: Macrofauna · Meiofauna · Total microbial biomass · Stable isotopes · Trophic structure

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Cite this article as: Quiroga E, Ortiz P, González-Saldías R, Reid B and others (2016) Seasonal benthic patterns in a glacial Patagonian fjord: the role of suspended sediment and terrestrial organic matter. Mar Ecol Prog Ser 561:31-50.

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