MEPS 506:99-113 (2014)  -  DOI:

Normalized biomass size spectra in high Antarctic macrobenthic communities: linking trophic position and body size

Eduardo Quiroga1,*, Dieter Gerdes2, Américo Montiel3, Rainer Knust2, Ute Jacob

1Pontificia Universidad Católica de Valparaíso (PUCV), Escuela de Ciencias del Mar, Av. Altamirano #1480, Casilla 1020, Valparaíso, Chile
2Alfred Wegener Institute for Polar and Marine Research, Columbusstrasse, 27568 Bremerhaven, Germany
3Instituto de la Patagonia, Universidad de Magallanes, Av. Bulnes #01855, Casilla 113-D, Punta Arenas, Chile
*Corresponding author:

ABSTRACT: Normalized biomass size spectra (NBSS) and the stable nitrogen isotopic composition of food webs were analyzed to determine the inter-specific relationships between trophic level (measured as δ15N) and body size in macrobenthic communities living on the continental shelf of the southeastern Weddell Sea (SEWS). We found that the relationship between trophic level and body size for the whole macrobenthic community was not significant (r2 = 0.08, p > 0.05), probably associated with biomass accumulated in the larger body size fractions, which are represented particularly by suspension feeders such as sponges and tunicates. We used an alternative method of studying trophic structure of the aquatic communities based on the distribution of residuals of the NBSS. Here we demonstrate how residual distribution exhibited dome-like patterns, which may offer an additional quantitative tool for studying the relationship between trophic level and body size. These domes of biomass represent trophic positions derived from relationships between the body size distribution of the predators in one trophic position and their prey in another. We found 4 well defined domes of biomass, which appear when large benthic species are abundant, especially favored in an environment with high organic matter flux. A significant positive relationship (r2 = 0.59, p < 0.05) between the trophic level and residuals derived from NBSS suggests that these domes might be considered as functional groups comprising organisms from different trophic levels. We suggest that dome-like patterns in the biomass size spectra can provide a robust framework for conceptualizing and statistically modeling trophic levels of macrobenthic communities.

KEY WORDS: Macrofauna · Trophic spectrum · Trophic level · Stable isotopes

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Cite this article as: Quiroga E, Gerdes D, Montiel A, Knust R, Jacob U (2014) Normalized biomass size spectra in high Antarctic macrobenthic communities: linking trophic position and body size. Mar Ecol Prog Ser 506:99-113.

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