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

Yunev, Oleg A.; Vedernikov, V. I.; Baştürk, Özden; Yılmaz, Ali Özgür; Kıdeyş, Ahmet E.; Moncheva, Snejana; Konovalov, Sergey

doi:10.3354/meps230011

Cited by 94 publications

(59 citation statements)

References 45 publications

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“…14 and 13b). This is in agreement with a change from relatively low rates of primary production and nutrient supply during the first period to high trophic conditions in more recent times (e.g., Sorokin, 1964;Cociasu et al, 1996;Konovalov and Murray, 2001;Yunev et al, 2002). The intermediate period of the most intense eutrophication from the late 1970s to the second half of the 1980s is characterized by a completely different pattern of pycnocline oxygenation (Fig.…”

Section: Multidecadal Hypoxia Trends In Stratified Basinsan Example Fsupporting

confidence: 69%

Investigating hypoxia in aquatic environments: diverse approaches to addressing a complex phenomenon

et al. 2014

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Abstract. In this paper we provide an overview of new knowledge on oxygen depletion (hypoxia) and related phenomena in aquatic systems resulting from the EU-FP7 project HYPOX ("In situ monitoring of oxygen depletion in hypoxic ecosystems of coastal and open seas, and landlocked water bodies", www.hypox.net). In view of the anticipated oxygen loss in aquatic systems due to eutrophication and climate change, HYPOX was set up to improve capacities to monitor hypoxia as well as to understand its causes and consequences.Temporal dynamics and spatial patterns of hypoxia were analyzed in field studies in various aquatic environments, including the Baltic Sea, the Black Sea, Scottish and Scandinavian fjords, Ionian Sea lagoons and embayments, and Swiss lakes. Examples of episodic and rapid (hours) occurrences of hypoxia, as well as seasonal changes in bottom-water oxygenation in stratified systems, are discussed. Geologically driven hypoxia caused by gas seepage is demonstrated. Using novel technologies, temporal and spatial patterns of watercolumn oxygenation, from basin-scale seasonal patterns to meter-scale sub-micromolar oxygen distributions, were resolved. Existing multidecadal monitoring data were used to demonstrate the imprint of climate change and eutrophication on long-term oxygen distributions. Organic and inorganic proxies were used to extend investigations on past oxygen conditions to centennial and even longer timescales that cannot be resolved by monitoring. The effects of hypoxia on faunal communities and biogeochemical processes were also addressed in the project. An investigation of benthic fauna is presented as an example of hypoxia-devastated benthic communities that slowly recover upon a reduction in eutrophication in a system where naturally occurring hypoxia overlaps with anthropogenic hypoxia. Biogeochemical investigations reveal that oxygen intrusions have a strong effect on the microbially mediated redox cycling of elements. Observations and modeling studies of the sediments demonstrate the effect of seasonally changing oxygen conditions on benthic mineralization pathways and fluxes. Data quality and access are crucial in hypoxia research. Technical issues are therefore also addressed, including the availability of suitable sensor technology to resolve the gradual changes in bottom-water oxygen in marine systems that can be expected as a result of climate change. Using cabled observatories as examples, we show how the benefit of continuous oxygen monitoring can be maximized by adopting proper quality control. Finally, we discuss strategies for state-of-the-art data archiving and dissemination in compliance with global standards, and how ocean observations can contribute to global earth observation attempts.

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Section: Multidecadal Hypoxia Trends In Stratified Basinsan Example Fsupporting

confidence: 69%

Investigating hypoxia in aquatic environments: diverse approaches to addressing a complex phenomenon

et al. 2014

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“…Because in situ measurements on this spatiotemporal scale are unavailable, we use remotely sensed chlorophyll a concentration products to determine and analyze the water quality over ten years across the whole Great Barrier Reef. This approach has been 30 successfully employed in other long-term water quality case studies in a variety of coastal locations, such as in the Chesapeake Bay (Harding and Perry 1997), the Black Sea (Yunev et al 2002), and the Basque coastal area (Novoa et al 2012). …”

Section: Remote Sensing Of Chlorophyll Amentioning

confidence: 99%

The Relationship between Tropical Cyclone Activity, Nutrient Loading, and Algal Blooms over the Great Barrier Reef

Parker

Lynch

Spera

et al. 2017

Preprint

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Abstract. The Great Barrier Reef, the world's largest coral reef ecosystem, is subject to many environmental stressors. This study utilizes remotely sensed Moderate Resolution Imaging Spectroradiometer (MODIS) chlorophyll a concentration data to explore statistically significant relationships between local-scale tropical cyclone disturbance and relative water quality 10 between 2004-2014. The study reveals that tropical cyclone activity reduces water quality at 8-and 16-day time lags.Relationships suggest that at early stages (during and just after cyclone activity) algal response is induced primarily through wind-driven sediment re-suspension. However, wind speed in isolation only increases minimum levels of chlorophyll a, rather than mean or extreme upper values. At greater time lags (16-day), it is suggested that nutrient runoff from rainfall (and perhaps storm surge) increase phytoplankton activity, leading to detrimental ecological effects. The analyses systematically 15 demonstrate the dominance of tropical cyclone size on mean and extreme values of chlorophyll a during and after tropical cyclone activity (at 0-, 8-, and 16-day time lags). Both the total area affected and the area from which nutrients can be extracted have more impact on chlorophyll a concentrations than either the duration or intensity of the cyclone. Findings indicate that efforts to reduce nutrient and sediment leaching into the reef lagoon from the Queensland coastal lands need to be continued and improved. This will be particularly important in the context of climate change, since tropical cyclone 20 frequency, dynamics and characteristics are likely to change.

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“…Changes in Chl-a and PP have been monitored in different regions of the Black Sea for several decades (Finenko, 1967;Vedernikov et al, 1980Vedernikov et al, , 1983Yunev, 1989;Krupatkina et al, 1990Krupatkina et al, , 1991Berseneva, 1993;Vedernikov & Demidov, 1993;Yilmaz et al, 1998;Bologa et al, 1999;Demidov, 1999;Kopelevich et al, 2002;Yunev et al, 2002). Spatial and seasonal variations in Chl-a in the Black Sea were assessed using CZCS satellite data from 1978 to 1986, before the onset of dramatic changes in Chl-a biomass during the late 1980's (Vedernikov & Demidov, 1993).…”

Section: Ertugrul Ağırbaşmentioning

confidence: 99%

“…Until 1988, the fishery was almost five times richer than the neighbouring Mediterranean Sea (Anonymous, 2000;Kideys, 1994). In recent years there have been some signs of recovery of the fishery (Yunev et al, 2002;Bodeanu et al, 2004;Mee, 2006), though the reasons for this have not been properly quantified.…”

Section: Introductionmentioning

confidence: 99%

“…It is a semi-enclosed and isolated environment, which has suffered from severe ecological changes over the last three decades (Zaitsev & Mamaev, 1997;Oguz, 2005). Excessive nutrient and pollutant input (Mee, 1992;Zaitsev & Mamaev, 1997), the introduction of the alien ctenophore species Mnemiopsis leidyi (Shiganova, 1998;Kideys & Romanova, 2001;Kideys, 2002), overfishing (Prodanov et al, 1997;Daskalov, 2002;Gucu, 2002) and recent changes in the physical structure of the water column as a result of climate change (Daskalov, 2003) have had a major impact on this ecosystem. The Black Sea supports a large-scale commercial fishery for countries that border the basin (Kideys, 2002;Agirbas et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Ağırbaş¹,

Tilstone²,

Feyzioglu³

2017

Turk. J. Fish. Aquat. Sci.

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A 12-year time series of SeaWiFS chlorophyll a (Chl-a), primary production (PP), sea surface temperature (SST), and meteorological wind speed were used to examine decadal changes in these parameters in the eastern and western Gyres of the Black Sea. In both Gyres, low wind speeds and SST led to higher PP. After 2004, there was a progressive decrease in PP and Chl-a, which co-varied with increasing SST. Chl-a and PP were significantly higher in the western Gyre compared to the eastern Gyre, especially from 1998 to 2004. Wind speed negatively correlated with PP in both Gyres, but the higher wind speed prior to relaxation in the western Gyre led to higher PP during spring and autumn. Variability in annual PP in both Gyres was coupled to fluctuations in the Multivariate ENSO Index (MEI), which affected the wind regime more in the eastern than in the western Gyre. The data suggest that localised wind regimes in the western gyre that are uncoupled from MEI, sustains higher PP in this area.

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

Cited by 94 publications

References 45 publications

Investigating hypoxia in aquatic environments: diverse approaches to addressing a complex phenomenon

Investigating hypoxia in aquatic environments: diverse approaches to addressing a complex phenomenon

The Relationship between Tropical Cyclone Activity, Nutrient Loading, and Algal Blooms over the Great Barrier Reef

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