scholarly journals Paleohydrology reconstruction and Holocene climate variability in the South Adriatic Sea

2013 ◽  
Vol 9 (1) ◽  
pp. 499-515 ◽  
Author(s):  
G. Siani ◽  
M. Magny ◽  
M. Paterne ◽  
M. Debret ◽  
M. Fontugne
Keyword(s):  
Climate Variability ◽  
Adriatic Sea ◽  
Isotope Composition ◽  
Climatic Conditions ◽  
Sea Surface ◽  
The South ◽  
Short Term ◽  
Central Mediterranean ◽  
The North ◽  
Holocene Period

Abstract. Holocene paleohydrology reconstruction is derived combining planktonic and benthic stable oxygen and carbon isotopes, sea surface temperatures (SSTs) and oxygen isotope composition of seawater (δ18Ow) from a high sedimentation core collected in the South Adriatic Sea (SAS). Core chronology is based on 10 AMS 14C measures on planktonic foraminifera and tephra layers. Results reveal two contrasted paleohydrological periods that reflect (i) a marked lowering of δ18Ow/salinity during the early to mid-Holocene (11.5 ka to 6.3 ka), including the two-step sapropel S1 deposition, followed during the mid- to upper Holocene by (ii) a prevailing period of increased salinity and enhanced arid conditions in the South Adriatic Basin. Superimposed on these trends, short-term centennial-scale hydrological events punctuated the Holocene period in the SAS. During the early to mid-Holocene, two main SST coolings together with prominent δ18Ow/salinity lowering delineate the sapropel S1 interruption and the post-sapropel phase between 7.3 to 6.3 ka. After 6 ka, centennial-scale δ18Ow and G. bulloides δ13C lowering, mostly centered between 3 to 0.6 ka, reflect short-term hydrological changes related to more intensive runoff of the Po and/or Apennine rivers. These short-term events, even of lesser amplitude compared to the early to mid-Holocene period, may have induced a lowering of sea surface density and consequently reduced and/or inhibited the formation of deep bottom waters in the SAS. Comparison of the emerging centennial- to millennial-scale hydrological record with previous climatic records from the central Mediterranean area and north of the Alps reveal possible synchronicities (within the radiocarbon-dating uncertainty) between phases of lower salinity in the SAS and periods of wetter climatic conditions around the north-central Adriatic Sea. Finally, wavelet analyses provide new clues about the potential origin of climate variability in the SAS, confirming the evidence for a mid-Holocene transition in the central Mediterranean climate and the dominance of a ~1670-yr periodicity after 6 ka, reflecting a plausible connection with the North Atlantic climate system.

scholarly journals Paleohydrology reconstruction and Holocene climate variability in the South Adriatic Sea

2012 ◽  
Vol 8 (5) ◽  
pp. 4357-4399 ◽  
Author(s):  
G. Siani ◽  
M. Magny ◽  
M. Paterne ◽  
M. Debret ◽  
M. Fontugne
Keyword(s):  
Climate Variability ◽  
Adriatic Sea ◽  
Short Interval ◽  
Sea Surface ◽  
The South ◽  
Short Term ◽  
Central Mediterranean ◽  
Middle Holocene ◽  
The North ◽  
Holocene Period

Abstract. Holocene paleohydrology reconstruction was derived combining planktic and benthic stable oxygen and carbon isotopes, sea surface temperatures (SSTs) and oxygen isotope composition of seawater (δ18Ow) from a high sedimentation core collected in the south Adriatic sea (SAS). Chronology of core is based on 10 AMS 14C measures on planktic foraminifera and tephra markers. Results reveal two contrasted paleohydrological periods that reflect (i) a marked lowering of δ 18Ow/salinity during the early to middle Holocene (11.5 ka to 6.3 ka), including the two-steps sapropel S1 deposition, followed during the middle to upper Holocene by (ii) a prevailed period of increased salinity and enhanced arid conditions in the south Adriatic basin. Superimposed on these trends, short-term centennial-scale hydrological events punctuated the Holocene period in the SAS. During the Early to Middle Holocene, a short-term SST cooling together with a prominent δ 18Ow/salinity lowering, more pronounced than during the sapropel S1 phase, delineates the sapropel S1 interruption. This short interval, coeval to the 8.2 ka event, is also distinguished by a resumption of deep-water convection in the SAS as indicated by stable isotope reconstruction on benthic forminifera. After 6 ka, centennial-scale δ18Ow and G. bulloides δ13C lowering, mostly centered between 3 to 0.6 ka, reflect short term hydrological changes related to a more intensive Po river runoff. These short-term events, even of lesser amplitude compared to the early to middle Holocene period, may have induced a lowering of sea surface density and consequently reduced and/or inhibited the formation of deep bottom waters in the SAS. Comparison of the emerging centennial to millennial-scale hydrological record with previous climatic records from the central Mediterranean area and north of the Alps revealed possible synchronicities (within the radiocarbon-dating uncertainty) between phases of lower salinity in SAS and periods of wetter climatic conditions around the north-central Adriatic Sea. Finally, wavelet analyses provide new clues about the potential origin of climate variability in the SAS confirming the evidence for a mid-Holocene transition in the Central Mediterranean climate and the dominance of a ~ 1700 yr periodicity after 6 ka that reflects a plausible connection with the North Atlantic climate system.

scholarly journals Deep-Water Cartilaginous Fishes in the Central Mediterranean Sea: Comparison between Geographic Areas with Two Low Impact Tools for Sampling

2021 ◽  
Vol 9 (7) ◽  
pp. 686
Author(s):  
Angela Carluccio ◽  
Francesca Capezzuto ◽  
Porzia Maiorano ◽  
Letizia Sion ◽  
Gianfranco D’Onghia
Keyword(s):  
Adriatic Sea ◽  
Fish Habitat ◽  
Conservation Status ◽  
Abundant Species ◽  
Cartilaginous Fish ◽  
Fish Diversity ◽  
Ionian Sea ◽  
Central Mediterranean ◽  
The North ◽  
North Western

Baited lander represents a low impact technique, an alternative to the traditional trawl sampling for collecting data on fish diversity and abundance, especially for threatened species such as Chondrichthyes living in sensitive habitats. In this study, distribution and abundance of cartilaginous fish were compared between two geographic areas, the southern Adriatic Sea and the north-western Ionian Sea, with two low impact sampling gears, an experimental bottom longline and a baited lander. Species diversity was evaluated by applying ecological indices and difference in mean abundances were tested using multivariate analysis. A total of 13 species of cartilaginous fish were collected. Significant differences in the assemblage recorded in the same area using different sampling tools were detected and no significant differences were detected among different areas explored with the same method. Using longline, the most abundant species collected in both areas was Galeus melastomus, while using lander, the most observed species were Dalatias licha in the southern Adriatic Sea and Hexanchus griseus in the north-western Ionian Sea. According to IUCN classification, of the 13 species collected, 2 are near threatened and 5 are threatened. A better governance of sensitive habitats coinciding with the essential fish habitat for these species would ensure them a better conservation status.

scholarly journals Operability Guidelines For Product Tanker In Heavy Weather In The Adriatic Sea

2014 ◽  
Vol 21 (1) ◽  
pp. 95-106
Author(s):  
Luka Mudronja ◽  
Marko Katalinić ◽  
Rino Bošnjak ◽  
Pero Vidan ◽  
Joško Parunov
Keyword(s):  
Wave Height ◽  
Adriatic Sea ◽  
Wave Spectrum ◽  
Extreme Weather ◽  
The South ◽  
Sea State ◽  
M Wave ◽  
The North ◽  
Limiting Values ◽  
Deck Wetness

AbstractThis paper presents operability guidelines for seafarers on a product tanker which navigates in the Adriatic Sea during heavy weather. Tanker route starts from the Otranto strait in the south to the island Krk in the north of Adriatic Sea. Heavy weather is caused by south wind called jugo (blowing from E-SE to SS-E, sirocco family). Operability guidelines are given based on an operability criteria platform for presenting ship seakeeping characteristics. Operability criteria considered in this paper are propeller emergence, deck wetness and bow acceleration of a product tanker. Limiting values of mentioned criteria determine sustainable speed. Heavy weather is described by extreme sea state of 7.5 m wave height. Wave spectrum used in this paper is Tabain spectrum which is developed specifically for Adriatic Sea. Seafarer's approach of decisions making in extreme weather is also shown and servers as a guideline for further research of the authors.

scholarly journals Qualified temperature, salinity and dissolved oxygen climatologies in a changing Adriatic Sea

2014 ◽  
Vol 11 (1) ◽  
pp. 331-390
Author(s):  
M. Lipizer ◽  
E. Partescano ◽  
A. Rabitti ◽  
A. Giorgetti ◽  
A. Crise
Keyword(s):  
Dissolved Oxygen ◽  
Adriatic Sea ◽  
Eastern Mediterranean ◽  
Temporal Stability ◽  
The South ◽  
The North ◽  
Synthetic Temperature ◽  
Oxygen Utilisation ◽  
Oxygen Minimum

Abstract. An updated climatology, based on a comprehensive dataset (1911–2009) of temperature, salinity and dissolved oxygen, has been produced for the whole Adriatic Sea with the Variational Inverse Method using the DIVA software. Climatological maps were produced at 26 levels and validated with Ordinary Cross Validation and with real vs. synthetic Temperature–Salinity diagram intercomparison. The concept of Climatology–Observation Misfit (COM) has been introduced as an estimate of the physical variability associated with the climatological structures. In order to verify the temporal stability of the climatology, long-term variability has been investigated in the Mid Adriatic and the South Adriatic Pits, regarded as the most suitable records of possible long-term changes. Compared with previous climatologies, this study reveals a surface temperature rise (up to 2 °C), a clear deep dissolved oxygen minimum in the South Adriatic Gyre and a bottom summer oxygen minimum in the North Adriatic. Below 100 m all properties profoundly differ between the Middle and the South Adriatic. The South Adriatic Pit clearly shows the remote effects of the Eastern Mediterranean Transient, while no effect is observed in Middle Adriatic Pits. The deepest part of the South Adriatic seems now to be significantly saltier (+0.18 since the period 1911–1914, with an increase of +0.018 decade−1 since the late 1940s) and warmer (+0.54 °C since 1911–1914), even though a long-term temperature trend could not be statistically demonstrated. Conversely, the Middle Adriatic Pits present a long-term increase in apparent oxygen utilisation (+0.77 mL L−1 since 1911–1914, with a constant increase of +0.2 mL L−1 decade−1 after the 1970s).

scholarly journals Climate variability of the last ~2700 years in the Southern Adriatic Sea: Coccolithophore evidences

The Holocene ◽  
2019 ◽  
Vol 30 (1) ◽  
pp. 53-64
Author(s):  
Antonio Cascella ◽  
Sergio Bonomo ◽  
Bassem Jalali ◽  
Marie-Alexandrine Sicre ◽  
Nicola Pelosi ◽  
...  
Keyword(s):  
Adriatic Sea ◽  
Regional Scale ◽  
Flood Frequency ◽  
Ice Age ◽  
Calcareous Nannofossils ◽  
Central Mediterranean ◽  
The North ◽  
Water Column Stratification ◽  
Florisphaera Profunda ◽  
The North Atlantic Oscillation

New information on palaeoenvironmental conditions over the past ~2700 years in the Central Mediterranean Sea have been acquired through the high-resolution study of calcareous nannofossils preserved in the sediment core SW104-ND14Q recovered in the Southern Adriatic Sea (SAS) at 1013-m water depth. The surface water properties at this open SAS site are sensitive to atmospheric forcing (acting both at local and regional scale) and the North Ionian Sea driven inflowing waters. Our data show a relationship between reworked coccolith abundances, flood frequency across the Southern Alps and the North Atlantic Oscillation (NAO) confirming their value as indicator of runoff/precipitation. Changes in the abundance of the opportunistic (r-strategist) species Emiliania huxleyi and deep dweller taxa Florisphaera profunda were used to reconstruct the upper water column stratification and associated changes in coccolithophorid productivity. The negative correlation between reworked coccoliths and the N-Ratio ( r = −0.44; p = 6−7) suggest that fresh water induced stratification is a controlling factor of the SAS coccolithophorid production. High coccolithophorid productivity levels occurred during dry periods and/or time intervals of inflowing salty and nutrient-rich Levantine Intermediate Waters favouring convection while lower levels took place during high freshwater discharge, mainly during the ‘Little Ice Age’ and two centennial scale intervals of weakest NAO around 200 BCE and 500 CE.

scholarly journals Southern Hemisphere anticyclonic circulation drives oceanic and climatic conditions in late Holocene southernmost Africa

2017 ◽  
Vol 13 (6) ◽  
pp. 649-665 ◽  
Author(s):  
Annette Hahn ◽  
Enno Schefuß ◽  
Sergio Andò ◽  
Hayley C. Cawthra ◽  
Peter Frenzel ◽  
...  
Keyword(s):  
South Africa ◽  
Climatic Conditions ◽  
Sea Surface ◽  
South Coast ◽  
Ice Age ◽  
Sea Surface Temperatures ◽  
The South ◽  
Anticyclonic Circulation ◽  
Surface Temperatures ◽  
Precipitation Regimes

Abstract. Due to the high sensitivity of southern Africa to climate change, a reliable understanding of its hydrological system is crucial. Recent studies of the regional climatic system have revealed a highly complex interplay of forcing factors on precipitation regimes. This includes the influence of the tropical easterlies, the strength of the southern hemispheric westerlies as well as sea surface temperatures along the coast of the subcontinent. However, very few marine records have been available in order to study the coupling of marine and atmospheric circulation systems. Here we present results from a marine sediment core, recovered in shallow waters off the Gouritz River mouth on the south coast of South Africa. Core GeoB18308-1 allows a closer view of the last  ∼  4 kyr. Climate sensitive organic proxies, like the distribution and isotopic composition of plant-wax lipids as well as indicators for sea surface temperatures and soil input, give information on oceanographic and hydrologic changes during the recorded time period. Moreover, the micropaleontology, mineralogical and elemental composition of the sediments reflect the variability of the terrigenous input to the core site. The combination of down-core sediment signatures and a catchment-wide provenance study indicate that the Little Ice Age ( ∼  300–650 cal yr BP) was characterized by climatic conditions favorable to torrential flood events. The Medieval Climate Anomaly ( ∼  950–650 cal yr BP) is expressed by lower sea surface temperatures in the Mossel Bay area and humid conditions in the Gouritz River catchment. These new results suggest that the coincidence of humid conditions and cooler sea surface temperatures along the south coast of South Africa resulted from a strengthened and more southerly anticyclonic circulation. Most probably, the transport of moisture from the Indian Ocean by strong subtropical easterlies was coupled with Agulhas Bank upwelling pulses, which were initiated by an increase in Agulhas Current strength.

scholarly journals Application of interval approach to pattern recognition for identification of preceeding baric structures that determine extreme thermal modes in the South-Kuril area in summer

2021 ◽  
Vol 201 (2) ◽  
pp. 470-483
Author(s):  
T. A. Shatilina ◽  
G. Sh. Tsitsiashvili ◽  
T. V. Radchenkova
Keyword(s):  
East Asia ◽  
Sea Surface ◽  
Okhotsk Sea ◽  
The South ◽  
West Pacific ◽  
North West ◽  
The North ◽  
Interval Approach ◽  
Warm Summer ◽  
Extreme Cold

Patterns of atmosphere baric fields preceeded to development of extreme thermal modes in the South-Kuril area in summer are identified using the interval approach to their recogni tion. The best recognition rates are noted for the field of AT 500 hPa over the region of East Asia in February, March, May, and June. Extreme cold summer conditions in the South-Kuril area in summer were preceeded by development of AT 500 hPa trough and baric depression at the sea surface over East Asia in these winter and spring months. Warm summer conditions in the South-Kuril area were preceeded by opposite patterns, as AT 500 hPa ridge over the North-West Pacific and high pressure over the Okhotsk Sea, with positive anomalies of H500 height over the North-West Pacific and Kuril Islands.

scholarly journals Latitudinal variations of δ<sup>30</sup>Si and δ<sup>15</sup>N signatures along the Peruvian shelf: quantifying the effects of nutrient utilization versus denitrification over the past 600 years

2018 ◽  
Author(s):  
Kristin Doering ◽  
Claudia Ehlert ◽  
Philippe Martinez ◽  
Martin Frank ◽  
Ralph Schneider
Keyword(s):  
Isotope Composition ◽  
Nitrogen Isotope ◽  
Nutrient Utilization ◽  
Climatic Conditions ◽  
Ice Age ◽  
Silicon Isotope ◽  
Short Term ◽  
The Past ◽  
Subsurface Waters ◽  
Minimum Zone

Abstract. The sedimentary stable nitrogen isotope compositions of bulk organic matter (δ15Nbulk) and silicon isotope composition of diatoms (δ30SiBSi) both mainly reflect the degree of past nutrient utilization by primary producers. However, in ocean areas where anoxic and suboxic conditions prevail, the δ15Nbulk signal ultimately recorded within the sediments is also influenced by water column denitrification causing an increase in the subsurface δ15N signature of dissolved nitrate (δ15NO3−) upwelled to the surface. Such conditions are found in the oxygen minimum zone off Peru, where at present an increase in subsurface δ15NO3− from North to South along the shelf is observed due to ongoing denitrification within the pole-ward flowing subsurface waters, while the δ30Si signature of silicic acid (δ30Si(OH)4) at the same time remains unchanged. Here, we present three new δ30SiBSi records between 11° S and 15° S and compare these to previously published δ30SiBSi and δ15Nbulk records from Peru covering the past 600 years. We present a new approach to calculate past subsurface δ15NO3− signatures based on the correlation of δ30SiBSi and δ15Nbulk signatures at a latitudinal resolution for different time periods. Our results show source water δ15NO3− compositions during the last 200 years, the Current Warm Period (CWP) and during short-term arid events prior to that, which are close to modern values increasing southward from 7 to 10 ‰ (between 11° S and 15° S). In contrast, humid conditions during the Little Ice Age (LIA) reflect consistently low δ15NO3− values between 6 and 7.5‰. Furthermore, we are able to relate the short-term variability in both isotope compositions to changes in the ratio of nutrients (NO3− : Si(OH)4) taken up by different dominating phytoplankton groups (diatoms and non-siliceous phytoplankton) under the variable climatic conditions of the past 600 years.

scholarly journals Analysis and revision of the Miocene boreal faunae of bivalve mollusks of the South Sakhalin

2020 ◽  
Author(s):  
В.Д. ХУДИК ◽  
Ю.Д. ЗАХАРОВ
Keyword(s):  
Japan Sea ◽  
Climatic Conditions ◽  
Bivalve Mollusks ◽  
The South ◽  
The North ◽  
Initial Stage ◽  
The Japan Sea ◽  
South Sakhalin ◽  
Early Neogene ◽  
Climatic Cooling

Приведены результаты изучения остатков фаун двустворчатых моллюсков из миоценовых отложений Южного Сахалина. Их анализ позволил выделить три бореальных комплекса моллюсков: невельский, раннечеховский и курасийский, фиксирующие периоды похолодания климата в миоцене региона. Изучение неогеновых представителей родов Lucinoma и Mya позволило обозначить среди них ряд таксонов, имеющих стратиграфическое значение. Установленное присутствие тепловодных двустворок в фаунах позднечеховского времени Южного Сахалина, очевидно, отражает собой начальный этап тенденции нарастающего потепления климата в миоцене региона с климатическим оптимумом в верхнедуйско-сертунайское время. Высказывается следующее мнение: неустойчивые климатические условия в позднем палеогене – раннем неогене северной части Япономорского региона могли быть основной причиной возникновения здесь одного из мощных центров эволюции морских малакофаун бореальных районов северной Пацифики. The results on the studying of the faunae of bivalve mollusks remains from miocene deposits of the South Sakhalin are presented. The analysis of the last ones allowed distinguishing the following three boreal assemblages of mollusks: Nevelskiy, early Chekhovskiy and Kurasiiskiy, recording the period of climatic cooling in miocene of the region. Studying of Neogene representatives of Lucinoma and Mya generas allowed identifying some taxa among them which have stratigraphic significance. The detected presence of warm water bivalves in the faunae of the late Chekhovsky time of the South Sakhalin appears to reflect the initial stage of the tendency of the intensifying climate warming happened during miocene, with climatic optimum during the Verkhneduysky – Sertunaysky times. An opinion is expressed that the unstable climatic conditions in the northern part of the Japan Sea region during late Paleogene – early Neogene could have been the main reason for originating of one of the high-potential centers of evolution of the marine malacofaunae of boreal regions of the North Pacific.

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