Invasion dynamics of the alien ctenophore Mnemiopsis leidyi and its impact on anchovy collapse in the Black Sea

The mechanisms governing the unprecedented 1989-90 anchovy-Mnemiopsis shift event in the Black Sea were evaluated with a coupled model of bioenergetic-based anchovy population dynamics and lower trophic food web structure. Simulations showed that a combination of direct and density-dependent effects of overfishing, eutrophication-induced nutrient enrichment, climate-induced over-enrichment and temperature-controlled Mnemiopsis spring production were involved in the shift. Eutrophication made the system vulnerable to further enrichment through the change of regional climate to a severe winter regime during 1985-87. While Mnemiopsis was acclimating to its new environment, increasing nitrate flux into the euphotic layer enhanced the carrying capacity of the system, but a disproportionate Mnemiopsis biomass increase was delayed until spring temperature conditions returned to normal in 1988-89. Enhanced carrying capacity provided a competitive advantage of food consumption to Mnemiopsis compared with anchovy, and warm spring temperature conditions promoted their spring-summer production. Prevalent high fishery pressure and increasing impact of Mnemiopsis on the food web further induced the anchovy stock collapse. However, the shift event did not result in alternation of the system to a new totally Mnemiopsis-invaded quasi-stable regime. Instead, anchovy started recovering when the subsequent strong 1991-93 cooling regime limited the Mnemiopsis population growth. Our analysis indicated that the switch of a large marine ecosystem to a totally gelatinous invader-dominated state requires extremely strong environmental perturbations. More often, environmental disturbances create a suitable niche for an alien gelatinous invader to become a member of the food web structure, and to share food resources with the native small pelagic fish community.


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...
Regional peculiarities of community-wide trophic cascades in strongly degraded Black Sea food web
Oguz, Temel; Salihoğlu, Barış; Moncheva, Snejana; Abaza, Valeria (2012-04-01)
The community-wide trophic cascade due to collapsed fish stocks and population outburst of invasive predators after the early 1990s resulted in different pelagic and benthic food web structures in the Black Sea. The northeastern region assumed their most simplified forms characterized by increasing mesozooplankton and polychaete biomass. The ecological degradation is more severe in the northwestern part, whereas the southern basin maintains an anchovy fishery under relatively weak gelatinous predation.
Modeling the impact of climate variability on Black Sea anchovy recruitment and production
Güraslan, Ceren; Fach Salihoğlu, Bettina Andrea; Oğuz, Temel (2014-09-01)
The connection of climate variability with anchovy spawning and recruitment in the Black Sea in particular, and other ecosystems in general, was studied using a two-way coupled lower trophic level and anchovy bioenergetics model. Climate variability was represented by a 50-yr time series of daily temperature and vertical mixing rates with stochastic variations. Temperature was found to be the dominant factor influencing early life stages and hence population dynamics of Black Sea anchovy as marked by a high...
Population dynamics, ingestion, growth and reproduction rates of the invader Beroe ovata and its impact on plankton community in Sevastopol Bay, the Black Sea
Finenko, GA; Romanova, ZA; Abolmasova, GI; Anninsky, BE; Svetlichny, LS; Hubareva, ES; Bat, L; Kıdeyş, Ahmet Erkan (2003-05-01)
The impact of the introduced ctenophore Beroe ovata on its prey Mnemiopsis leidyi, another invader ctenophore voraciously feeding on mesozooplankton, and consequently on the mesozooplankton community, was evaluated by undertaking both laboratory and field studies in the northern Black Sea. Ingestion and growth rates as well as the gross growth efficiency of B. ovata were estimated from laboratory experiments. The daily ration of ctenophores was related to food abundance within a wide range of prey concentra...
Microplastic consumption and physiological response in Acartia clausi and Centropages typicus: Possible roles of feeding mechanisms
Svetlichny, Leonid; Isinibilir, Melek; Mykitchak, Taras; Eryalcin, Kamil Mert; Turkeri, Ezgi E.; Yuksel, Esin; Kıdeyş, Ahmet Erkan (2021-03-01)
Multi-day experiments were carried out with two Marmara Sea calanoid copepod species: Acartia clausi and Centropages typicus, to assess the possible role of the type of feeding on the consumption of microplastics and its influence on the rate of energy metabolism of these species. In a mixture of microplastic beads (6 mu m diameter) and algae Rhodomonas salina (5-10 mu m size range) with equal concentrations of about 5000 cells/beads mL(-1) the ambush feeder A. clausi consumed almost 5 times less microplast...
Citation Formats
T. Oğuz, B. A. Fach Salihoğlu, and B. Salihoğlu, “Invasion dynamics of the alien ctenophore Mnemiopsis leidyi and its impact on anchovy collapse in the Black Sea,” JOURNAL OF PLANKTON RESEARCH, pp. 1385–1397, 2008, Accessed: 00, 2020. [Online]. Available: