Fluctuations of Pelagic Species of the Open Black Sea During 1980–1995 and Possible Teleconnections

Niermann, U.; Kıdeyş, Ahmet E.; Kovalev, Alexander; Мelnikov, V.V.; Белокопытов, В. Н.

doi:10.1007/978-94-011-4568-8_10

Cited by 24 publications

(20 citation statements)

References 40 publications

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“…and climatic factors are being examined (see reviews by Shiganova 1998, Vinogradov et al 1999. Niermann et al (1999) suggested that man-made and natural environmental impacts on the Black Sea ecosystem have had cumulative effect. Increasing euthrophication since the end of the 1960s has driven the pelagic ecosystem into an unsteady state with disturbed prey-predator relationships.…”

Section: Discussionmentioning

confidence: 99%

Long-term variations of surface chlorophyll a and primary production in the open Black Sea

Yunev¹,

Vedernikov²,

Baştürk³

et al. 2002

Mar. Ecol. Prog. Ser.

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Extensive data sets on surface chlorophyll a (chl a), depth-integrated primary production (DIPP) and phosphate (PO 4 , µM) averaged for the upper 25 m layer in 1964, 1973, 1978 and for a period (1980 to 1996) of regular measurements have been used to evaluate long-term changes in the upper portion of the euphotic layer of the entire open (>1000 m) Black Sea. After preliminary analysis of seasonal dynamics, special attention was given to data obtained during those periods of the year with relatively stable values, revealing interannual and long-term fluctuations and trends. Of 2 phytoplankton characteristics (chl a and DIPP), long-term trends were obtained only for chl a since only these data covered the entire open sea and all periods investiged. A positive correlation was found between DIPP (using 2 different 14 C methods: actual in situ and simulated in situ) and the more numerous chl a data for different monthly intervals, with significant correlation coefficients (r = 0.51 to 0.82). This means that the observed patterns in long-term variability for chl a may be valid also for DIPP. The results show that interannual fluctuations in chl a are more pronounced during the warm months, from approximately May to September. Chl a levels within this interval were moderate, with a mean of 0.15 ± 0.04 mg m -3 during the first 'quiet' period (1964 to 1986), but increased steadily at a rate of 0.06 mg m

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Section: Discussionmentioning

confidence: 99%

Long-term variations of surface chlorophyll a and primary production in the open Black Sea

Yunev¹,

Vedernikov²,

Baştürk³

et al. 2002

Mar. Ecol. Prog. Ser.

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“…These have been growingly used in the scientific literature, since they have potentials to explain large scale correlations in the variations of weather conditions, oceanic conditions and consequent ecosystem changes (e.g. Niermann et al, 1999). Although the north Atlantic Oscillation (NAO) has been found to have a strong impact on the Mediterranean weather (e.g.…”

Section: Introductionmentioning

confidence: 99%

Interannual variability of Black Sea's hydrodynamics and connection to atmospheric patterns

Capet

Barth

Beckers

et al. 2012

Deep Sea Research Part II: Topical Studies in Oceanography

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The long term variability of the Black Sea physical processes (e.g. temperature, main circulation, cold intermediate layer, sea level) and its relation to atmospheric conditions and large scale climate patterns are investigated using an eddy-resolving tridimensional model in combination with statistical tools (e.g Empirical Orthogonal Functions, Self Organizing Maps). First, the ability of the model to represent the interannual dynamics of the system is assessed by comparing the modeled and satellite sea surface temperature (SST) and sea level anomaly (SLA) decomposed into their dominant Empirical Orthogonal Functions (EOFs). The correlation between the spatial and temporal EOFs modes derived from model and satellite is usually satisfactory and this gives some confidence in using the model as a tool to investigate not only the SST and SLA dynamics but also the dynamics of connected variables.Then, the long term variability of the Black Sea hydrodynamics is assessed by decomposing into their dominant EOFs modeled SST, SLA and selected key hydrodynamical variables associated to the main circulation and vertical structure of the water column. Significant correlations between the EOFs associated to these variables are investigated in order to link the variability of surface fields and the internal dynamics of the system.In particular, the intensity of the general cyclonic circulation (the Rim current) is shown to impact strongly on (1) the mean sea level, (2) the SST response to air temperature (AT), (3) In order to appraise the variability of atmospheric conditions over the Black Sea during 1962-2000 and their role in driving the hydrodynamics, a self-organizing maps technique is used in order to identify spatial recurrent patterns of atmospheric fields (ie. AT, wind stress and curl).The impact on these patterns of large scale climatic variability over the north Atlantic, the Eurasia and Pacific Ocean (estimated by respectively the north Atlantic oscillation (NAO), the east Atlantic/west Russia oscillation (EA/WR) and the El Niño southern oscillation (ENSO) indexes) is assessed. Distinct time scales of influence of the large scale teleconnection patterns on the AT are identified : EA/WR drives the short scale (1-5 years) variations of SST, while the long term (>5 year) trends of the NAO drive the long term SST trends.The drastic changes that have occurred in the Black Sea deep sea ecosystem at the end of the 80's are connected to an intensification of the general circulation which has promoted an export of riverine materials from the eutrophicated north-western shelf to the deep sea.Finally, in the last two decades, we find an increased duration of persistent atmospheric anomalies regime that have the potentials to drive the system away from its average state as occurred in the late 80s. If persistent in the future, such long lasting atmospheric anomalies may have a significant impact on the ecosystem functioning.

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“…Both regional anthropogenic impacts (increased water pollutants, eutrophication, overfishing, and an outbreak of the alien predator Mnemiopsis leidyi, etc.) and changes in the atmospheric and hydrological regimes of the basin related to large-scale climatic oscillations have been reported as possible causes for the changes in the Black Sea pelagic ecosystem after the second half of the 1980s (Niermann et al 1999, Vinogradov et al 1999, Kideys 2002.…”

Section: Introductionmentioning

confidence: 99%

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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Fluctuations of Pelagic Species of the Open Black Sea During 1980–1995 and Possible Teleconnections

Cited by 24 publications

References 40 publications

Long-term variations of surface chlorophyll a and primary production in the open Black Sea

Long-term variations of surface chlorophyll a and primary production in the open Black Sea

Interannual variability of Black Sea's hydrodynamics and connection to atmospheric patterns

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

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