Observations on the Rim Current structure, CIW formation and transport in the western Black Sea

Oğuz, Temel; Beşiktepe, Şükrü

doi:10.1016/s0967-0637(99)00028-x

Cited by 103 publications

(55 citation statements)

References 19 publications

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“…It is characterized by an interconnected series of cyclonic eddies and subbasin scale gyres which vary in size and shape across the basin and with depth. These features also display a substantial seasonal and interannual variability, which makes it impossible to select fixed stations or regions with well-defined hydrodynamic regimes (Oguz et al 1994, Ozsoy & Unluata 1997, Oguz & Besiktepe 1999. A further complication is that the data in the present investigation were collected during different cruises with differing objectives.…”

Section: Chlmentioning

confidence: 98%

Long-term variability of vertical chlorophyll a and nitrate profiles in the open Black Sea: eutrophication and climate change

Yunev¹,

Moncheva²,

Carstensen³

2005

Mar. Ecol. Prog. Ser.

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The objective of this study was to investigate long-term trends in the subsurface summer phytoplankton community and their underlying mechanisms in relation to nutrient enrichment of the open Black Sea. We analysed parameters describing the summer chlorophyll a (chl a) and annual mean nitrate depth distribution in terms of their maximum concentration and its depth, the mean nitrate gradient for the layer between the 2 maxima, and Secchi depth. Investigating the entire period from 1964 to 1996 did not reveal any direct relationship between the nitrate and phytoplankton levels. The nitrate level in the open Black Sea increased until 1984/85, corresponding with general increases in anthropogenic riverine nutrient inputs to the sea. Thus, the average maximum nitrate concentration and the nitrate gradient for all depth profiles increased between 1969 and 1984 and then remained constant. Despite the early increase in nitrate characteristics, the maximum in the chl a profile remained unaltered from 1964 to 1984. After the mid-1980s, the magnitude of the chl a profile gradually increased to 1991 and peaked with an exceptionally high concentration in 1992. In this same period there were only moderate fluctuations in the nitrate profile characteristics. The change of the summer phytoplankton biomass levels since 1984/85 coincided with an intensification of the Rim Current and the associated transport of nitrate to the euphotic zone. Prior to 1984/85 strong stratification and a deep halocline resulted in nitrate accumulation only, whereas uplifting of the halocline, combined with intensified advective currents, increased the transport of nitrate to the euphotic zone during the summer. This resulted in an associated increase in phytoplankton production and biomass in the following period. While this study shows that the open Black Sea, like the coastal regions, has been impacted by eutrophication, the response is different from the coastal region due to the different physical characteristics of the open waters.

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Section: Chlmentioning

confidence: 98%

Long-term variability of vertical chlorophyll a and nitrate profiles in the open Black Sea: eutrophication and climate change

Yunev¹,

Moncheva²,

Carstensen³

2005

Mar. Ecol. Prog. Ser.

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“…Chashchin et al (2015) suggested that factors such as wind direction, sea surface temperature distribution and currents are the most critical factors for Black Sea anchovy migration. The Black Sea circulation is highly variable and dominated by mesoscale eddies, meanders and filaments (Oguz et al, 1994;Oguz and Besiktepe, 1999;Korotaev et al 2003). Incorporating this variability into our modeling approach by using SSH satellite-derived currents covers most of the effect of winds, salinity, eddy formation and frontal features that are of important features of the Black Sea circulation.…”

Section: Satellite Datamentioning

confidence: 99%

Understanding the Impact of Environmental Variability on Anchovy Overwintering Migration in the Black Sea and its Implications for the Fishing Industry

2017

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Black Sea anchovy (Engraulis encrasicolus) undertake extensive overwintering migrations every fall from nursery grounds to warmer overwintering areas located on the south-eastern coast of the Black Sea. During migration and particularly upon arrival at the Anatolian coast, they support an important fishery and valuable source of income for the regional community. Black Sea anchovy have undergone significant stock fluctuations partly related to climatic conditions; for example, migrating anchovy schools arrived late or failed to arrive at the Anatolian coast when fall temperatures increased. It is therefore of importance to understand the conditions required for successful overwintering migration and explore different migration routes. This study invokes a Lagrangian modeling approach applied to satellite derived circulation and temperature data as a first attempt to model anchovy migration dynamics in the Black Sea. This modeling approach takes the influence of the physical environment into account, while the quality of overwintering grounds, adaptive, schooling, and homing behavior is neglected. The model is used to investigate the possible influence of interannual and seasonal variability of temperature and surface currents, as well as the influence of migration behavior on the success of anchovy overwintering migration for both the Black Sea and Azov Sea anchovy. The results of the present work show the possibility that overwintering anchovy fished along the Turkish Eastern Anatolian coast may not exclusively originate from the northwestern shelf, but mainly from the eastern Black Sea basin. Migration pathways are identified for both Black Sea and Azov Sea anchovy, which are of importance for the national fisheries efforts of riparian countries. The modeling results are in agreement with general patterns of anchovy migration given in the literature indicating that the physical environment may be a major factor in shaping general migration patterns. Simulation results are used to hypothesize about alternatives to previously determined migration routes and provide potential reasons that explain the inability of the Bulgarian anchovy fishery to recover. Results show that the intensity and timing of autumnal cooling, coupled with current Guraslan et al.Environmental Impact on Anchovy Overwintering Migration strength, can be of significant importance in determining annual and seasonal variability of migration success. Considering the need for fisheries management to account for the variability in fishable overwintering anchovy stocks a modeling approach as developed in the current study may provide such a tool.

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“…In addition, the mesoscale circulation is characterized by a number of anticyclonic eddies forming on the coastal side of the Rim Current: Bosphorus, Batumi, Sukhumi, Caucasus, Kerch, Crimea, Sevastopol, Danube, Constantsa, and Kaliakra eddies (Figure 1). Current speeds in the upper layer of the Rim current are 50-150 cm/s (Oguz and Besiktepe, 1999) and meanders of the Rim Current have a typical time scale of Figure 1. Schematic of the Black Sea general surface circulation (reproduced from Korotaev et al, 2003).…”

Section: Black Sea Circulationmentioning

confidence: 99%

Untitled

Fach¹

2014

Turk. J. Fish. Aquat. Sci.

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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)(2002)(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, representing the time it generally takes for anchovy eggs to develop into juveniles. Each individual was subject to somatic growth whose temperature dependence was calculated from satellite derived sea surface temperature data.Model results indicate that larval dispersal in the Black Sea is strongly controlled at the basin scale by the Rim Current circulation and its two cyclonic basin-wide gyres. It is locally controlled by mesoscale eddies. Consistent with the observed circulation fields, a strong meridional transport exists from the northern to the southern coastal zone along the western coast and the central basin. The peripheries of both the western and the eastern cyclonic gyres are also associated with strong larval transport from the southern coast to offshore areas. Elsewhere the connectivity between different regions is not as well pronounced due to weaker and patchy current fields. Variability in the dispersal of larvae is considerable when comparing different years and seasons and should be taken into account when designing networks of Marine Protected Areas in the Black Sea. Keywords: Black Sea anchovy larvae, Black Sea circulation, connectivity, Lagrangian modeling, temperature dependence. Karadeniz'deki Hamsi Dağılımı ve Bölgeler Arası Bağlantısı üzerine Hidrodinamik Proseslerin Etkisinin Modellenmesi ÖzetKaradeniz hamsi larvalarının (Engraulis encrasicolus ponticus) Karadeniz baseninde dağılım mekanizmaları, geliştirilen bir birey tabanlı hamsi larva modelinin üç yıllık (2001)(2002)(2003) altimetre verisinden hesaplanmış yüzey akıntıları kullanılarak bir Lagrangian modeline entegrasyonu ile araştırılmıştır. Model içinde hamsi yumurtalarını temsil eden parçacıklar HaziranAğustos ayları arasında farklı noktalarda bırakılmış ve zamana bağlı hareketleri takip edilmiştir. Hamsi yumurtalarının juvenil bireye gelişim süresi (ortalama) olan 36 gün boyunca model içinde bu parçacıklar akıntıya bağlı hareket etmiştir. Daha sonra bu bireylerin uydu verisinden hesaplanan yüzey suyu sıcaklık verisine bağlı olarak somatik büyümeleri hesaplanmıştır.Model sonuçları göstermiştir ki Karadeniz'de basen ölçeğinde larval dağılımı kontrol eden en büyük faktör kıyı akıntısı (Rim Current) ve iki büyük ölçekli siklonik döngüdür. Yerel ölçekte ise orta ölçek (mesoscale) girdaplar önem kazanır. Gözlemlenen akıntı sistemleri ile de tutarlı olarak, orta ve batı basende kuzey kıyılarından güneye güçlü bir boylamsal taşınım oluşur. Model sonuçları ayrıca batı ve doğu siklonik döngülerinin çevrelerinde güney sahillerinden ...

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Observations on the Rim Current structure, CIW formation and transport in the western Black Sea

Cited by 103 publications

References 19 publications

Long-term variability of vertical chlorophyll a and nitrate profiles in the open Black Sea: eutrophication and climate change

Long-term variability of vertical chlorophyll a and nitrate profiles in the open Black Sea: eutrophication and climate change

Understanding the Impact of Environmental Variability on Anchovy Overwintering Migration in the Black Sea and its Implications for the Fishing Industry

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