An indicator-based evaluation of Black Sea food web dynamics during 1960-2000

Four Ecopath mass-balance models were implemented for evaluating the structure and function of the Black Sea ecosystem using several ecological indicators during four distinctive periods (1960s, 1980-1987,1988-1994 and 1995-2000). The results exemplify how the Black Sea ecosystem structure started to change after the 1960s as a result of a series of trophic transformations, i.e., shifts in the energy flow pathways through the food web. These transformations were initiated by anthropogenic factors, such as eutrophication and overfishing, that led to the transfer of large quantities of energy to the trophic dead-end species, which had no natural predators in the ecosystem, i.e., jellyfish whose biomass increased from 0.03 g C m(-2) in 1960-1969 to 0.933 g C m(-2) in 1988-1994. Concurrently, an alternative short pathway for energy transfer was formed that converted significant amounts of system production back to detritus. This decreased the transfer efficiency of energy flow from the primary producers to the higher trophic levels from 9% in the 1960s to 3% between 1980 and 1987. We conclude that the anchovy stock collapse and successful establishment of the alien comb-jelly Mnemiopsis in 1989 were rooted in the trophic interactions in the food web, all of which were exacerbated because of the long-term establishment of a combination of anthropogenic stressors.


A coupled plankton-anchovy population dynamics model assessing nonlinear controls of anchovy and gelatinous biomass in the Black Sea
OĞUZ, Temel; Salihoğlu, Barış; Fach Salihoğlu, Bettina Andrea (2008-01-01)
A coupled model of lower trophic levels and anchovy Engraulis encrasicolus ponticus population dynamics was developed to analyze the mechanisms controlling sharp anchovy and gelatinous zooplankton biomass transitions from the 1960s to the 1980s in the Black Sea. An increase in anchovy stocks from estimated low (similar to 300 kt) to moderate (similar to 700 kt) in the late 1960s was related to weakening piscivore predation pressure, slight nutrient enrichment of the basin during an early eutrophication phas...
Modeling the influence of hydrodynamic processes on anchovy distribution and connectivity in the black sea Karadeniz'deki hamsi dağılımı ve bölgeler arası bağlantısı üzerine hidrodinamik proseslerin etkisinin modellenmesi
Fach Salihoğlu, Bettina Andrea (2014-01-01)
Dispersal mechanisms of Black Sea anchovy larvae (Engraulis encrasicolus ponticus) across the Black Sea were studied with an individual based anchovy larvae model embedded in a Lagrangian model using surface currents calculated from daily dynamic height topography maps of altimeter data during a period of three years (2001-2003). Particles representing anchovy eggs were released at different sites during June to August and their movement was tracked over time. Drifters were advected for 36 days, representin...
A physical-biochemical model of plankton productivity and nitrogen cycling in the Black Sea
Oguz, T; Ducklow, HW; Malanotte-Rizzoli, P; Murray, JW; Shushkina, EA; Vedernikov, VI; Unluata, U (1999-04-01)
A one-dimensional, vertically resolved, physical-biochemical upper ocean model is utilized to study plankton productivity and nitrogen cycling in the central Black Sea region characterized by cyclonic gyral circulation. The model is an extension of the one given by Oguz et al. (1996, J, Geophys. Res. 101, 16585-16599) with identical physical characteristics but incorporating a multi-component plankton structure in its biological module, Phytoplankton are represented by two groups, typifying diatoms and flag...
The diel vertical distribution of zooplankton in the southeast Black Sea
Erkan, F.; Gücü, Ali Cemal; Zagorodnyaya, J. (2000-01-01)
The diel changes in the vertical distribution of zooplankton in the southeast Black Sea were described in this study. The zooplankton were sampled using two different sampling methods throughout one day in October 1996 and July 1997 at the same station. The zooplankton counts, the length measurements and biomass estimates showed that the zooplankton in the southeast Black Sea is dominated by small organisms, among which Noctiluca scintillans is the dominant species. In the vertical distribution of zooplankt...
Nonlinear dynamics of the Black Sea ecosystem and its response to anthropogenic and climate variations
Akoğlu, Ekin; Salihoğlu, Barış; Department of Marine Biology and Fisheries (2013)
The main objective of this research is to i) provide a quantitative understanding of the changes in the Black Sea ecosystem between 1960 – 1999, ii) to identify its food web dynamics including the infamous anchovy – Mnemiopsis shift in 1989, and iii) utilizing this understanding to explore future progressions of the Black Sea ecosystem under predicted future physical and biogeochemical changes. For this purpose, three different but complementary approaches were used all of which were detailed under three di...
Citation Formats
E. Akoğlu, B. Salihoğlu, and C. SOLİDORO, “An indicator-based evaluation of Black Sea food web dynamics during 1960-2000,” JOURNAL OF MARINE SYSTEMS, pp. 113–125, 2014, Accessed: 00, 2020. [Online]. Available: