Trophic dynamics of deep-sea megabenthos are mediated by surface productivity

PLoS One. 2013 May 17;8(5):e63796. doi: 10.1371/journal.pone.0063796. Print 2013.

Abstract

Most deep-sea benthic ecosystems are food limited and, in the majority of cases, are driven by the organic matter falling from the surface or advected downslope. Species may adapt to this scarceness by applying a wide variety of responses, such as feeding specialisation, niche width variation, and reduction in metabolic rates. The Mediterranean Sea hosts a gradient of food availability at the deep seafloor over its wide longitudinal transect. In the Mediterranean, broad regional studies on trophic habits are almost absent, and the response of deep-sea benthos to different trophic conditions is still speculative. Here, we show that both primary and secondary production processes taking place at surface layers are key drivers of deep-sea food web structuring. By employing an innovative statistical tool, we interpreted bulk-tissue δ(13)C and δ(15)N isotope ratios in benthic megafauna, and associated surface and mesopelagic components from the 3 basins of the Mediterranean Sea at 3 different depths (1200, 2000, and 3000 m). The trophic niche width and the amplitude of primary carbon sources were positively correlated with both primary and secondary surface production indicators. Moreover, mesopelagic organic matter utilization processes showed an intermediate position between surface and deep benthic components. These results shed light on the understanding of deep-sea ecosystems functioning and, at the same time, they demand further investigation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Animals
  • Carbon Isotopes / metabolism
  • Fishes / physiology*
  • Food Chain*
  • Geography
  • Invertebrates / physiology*
  • Marine Biology
  • Mediterranean Sea
  • Models, Biological*
  • Nitrogen Isotopes / metabolism
  • Plankton / chemistry
  • Plankton / physiology*
  • Species Specificity

Substances

  • Carbon Isotopes
  • Nitrogen Isotopes

Grants and funding

This study was supported by the European Science Foundation BIOFUN project (CTM2007-28739-E), and the Spanish Ministry of Science and Innovation PROMETEO project (CTM2007-66316-C02/MAR). ST was funded by a JAE-PRE CSIC grant, and ERL was supported by a JAE-DOC CSIC postdoctoral grant, both with co-funding from the European Social Fund. JN was supported by a post-doc contract of the “Juan de la Cierva” program (Spanish Ministry of Economy and Competitiveness). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.