Global change in the trophic functioning of marine food webs

PLoS One. 2017 Aug 11;12(8):e0182826. doi: 10.1371/journal.pone.0182826. eCollection 2017.

Abstract

The development of fisheries in the oceans, and other human drivers such as climate warming, have led to changes in species abundance, assemblages, trophic interactions, and ultimately in the functioning of marine food webs. Here, using a trophodynamic approach and global databases of catches and life history traits of marine species, we tested the hypothesis that anthropogenic ecological impacts may have led to changes in the global parameters defining the transfers of biomass within the food web. First, we developed two indicators to assess such changes: the Time Cumulated Indicator (TCI) measuring the residence time of biomass within the food web, and the Efficiency Cumulated Indicator (ECI) quantifying the fraction of secondary production reaching the top of the trophic chain. Then, we assessed, at the large marine ecosystem scale, the worldwide change of these two indicators over the 1950-2010 time-periods. Global trends were identified and cluster analyses were used to characterize the variability of trends between ecosystems. Results showed that the most common pattern over the study period is a global decrease in TCI, while the ECI indicator tends to increase. Thus, changes in species assemblages would induce faster and apparently more efficient biomass transfers in marine food webs. Results also suggested that the main driver of change over that period had been the large increase in fishing pressure. The largest changes occurred in ecosystems where 'fishing down the marine food web' are most intensive.

MeSH terms

  • Animals
  • Biodiversity
  • Biomass
  • Climate Change
  • Conservation of Natural Resources*
  • Ecosystem
  • Fisheries / statistics & numerical data*
  • Fishes / physiology*
  • Food Chain*
  • Humans
  • Models, Statistical*
  • Oceans and Seas

Grants and funding

For AM, the present work was conducted while a master thesis at UMR 985 Ecology and ecosystem health, funded by Agrocampus Ouest (http://www.agrocampus-ouest.fr/). The work has been done in collaboration with the Institute for the Oceans and Fisheries at the University of British Columbia. This collaboration was funded by the Nippon Foundation-UBC Nereus Program (http://www.nippon-foundation.or.jp/; http://www.nereusprogram.org/). MC, HDP and WWLC acknowledge funding support from the Nippon Foundation-UBC Nereus Program. DP, MLDP and MC acknowledge funding support from the Sea Around Us (http://www.seaaroundus.org/), funded by the Paul G. Allen Family Foundation (http://www.pgafamilyfoundation.org/) and the Oak Foundation (http://oakfnd.org/). The funders had no role to play in study design, data collection and analysis, decision to publish, or preparation of the manuscript.