Abrupt transitions of the top-down controlled Black Sea pelagic ecosystem during 1960-2000: Evidence for regime-shifts under strong fishery exploitation and nutrient enrichment modulated by climate-induced variations

Oguz T., Gilbert D.

DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS, vol.54, no.2, pp.220-242, 2007 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 54 Issue: 2
  • Publication Date: 2007
  • Doi Number: 10.1016/j.dsr.2006.09.010
  • Journal Name: DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.220-242
  • Keywords: Black Sea, regime-shift, alternate states, eutrophication, overfishing, climatic variations, top-down and bottom-up controls, LONG-TERM CHANGES, NORTH-SEA, MNEMIOPSIS-LEIDYI, RED NOISE, TROPHIC CASCADES, PACIFIC, OCEAN, VARIABILITY, MANAGEMENT, COLLAPSE
  • Middle East Technical University Affiliated: No

Abstract

Functioning of the Black Sea ecosystem has profoundly changed since the early 1970s under cumulative effects of excessive nutrient enrichment, strong cooling/warming, over-exploitation of pelagic fish stocks, and population outbreak of gelatinous carnivores. Applying a set of criteria to the long-term (1960-2000) ecological time-series data, the present study demonstrates that the Black Sea ecosystem was reorganised during this transition phase in different forms of top-down controlled food web structure through successive regime-shifts of distinct ecological properties. The Secchi disc depth, oxic-anoxic interface zone, dissolved oxygen and hydrogen sulphide concentrations also exhibit abrupt transition between their alternate regimes, and indicate tight coupling between the lower trophic food web structure and the biogeochemical pump in terms of regime-shift events.