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Marine Ecology Progress Series

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MEPS 375:41-52 (2009)  -  DOI:

Quantity and bioavailability of sediment organic matter as signatures of benthic trophic status

Antonio Pusceddu1,*, Antonio Dell’Anno1, Mauro Fabiano2, Roberto Danovaro1

1Department of Marine Sciences, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona, Italy
2Department for the Study of the Territory and its Resources, University of Genoa, Corso Europa, 26, 16100 Genova, Italy

ABSTRACT: Tools used for assessing marine trophic status are generally based on water column characteristics, which, however, may provide unreliable classification of the benthic trophic status. Here, we provide evidence from the literature that quantity and bioavailability of sediment organic matter are reliable proxies to assess benthic marine trophic status. We compiled data on the protein, carbohydrate and lipid concentration of sediments from different oceanic and coastal regions and varying water depths. The concentration of these 3 components as a whole (biopolymeric carbon) was found to be significantly correlated (r = 0.84) with the total organic carbon concentration, suggesting that the biopolymeric fraction is representative of the total organic carbon pool. However, the systematic variation of the biopolymeric fraction was higher than that of total organic carbon concentrations, suggesting that biopolymeric carbon is a more sensitive proxy of benthic trophic status than is the total carbon pool. Furthermore, biopolymeric carbon was significantly correlated to the amount of phytopigments, indicating that biopolymeric carbon accumulation in the sediment is related to inputs of algal carbon. Biopolymeric carbon concentrations were also positively correlated to the sediment community oxygen consumption, suggesting that the progressive accumulation of biopolymeric carbon could be an additional co-factor potentially responsible for hypoxic or anoxic events. The enzymatically digestible and algal fractions of biopolymeric carbon decreased in sediments with increasing biopolymeric carbon content (i.e. eutrophic systems), suggesting that organic carbon in eutrophic sediments is mostly refractory in nature. We propose that a biopolymeric carbon concentration in the sediment of >2.5 mg C g–1, being associated with a bioavailable fraction of <10%, can be considered as a threshold level at which benthic consumers may experience mostly refractory organic carbon.

KEY WORDS: Marine sediments · Organic matter · Trophic status

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Cite this article as: Pusceddu A, Dell’Anno A, Fabiano M, Danovaro R (2009) Quantity and bioavailability of sediment organic matter as signatures of benthic trophic status. Mar Ecol Prog Ser 375:41-52.

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