scholarly journals Copepod Community Structure in Pre- and Post- Winter Conditions in the Southern Adriatic Sea (NE Mediterranean)

2020 ◽  
Vol 8 (8) ◽  
pp. 567
Author(s):  
Marijana Hure ◽  
Mirna Batistić ◽  
Vedrana Kovačević ◽  
Manuel Bensi ◽  
Rade Garić
Keyword(s):  
Adriatic Sea ◽  
Eastern Mediterranean ◽  
Central Area ◽  
Mesh Size ◽  
Early Spring ◽  
Winter Period ◽  
Late Winter ◽  
Intermediate Water ◽  
Copepod Community ◽  
Winter Conditions

Copepod communities were studied along an east-west transect in the oligotrophic Southern Adriatic Sea. This dynamic region is under the influence of various physical forces, including winter vertical convection, lateral exchanges between coastal and open sea waters, and ingression of water masses of different properties all of which occurred during the investigation periods. Depth-stratified samples were taken with a Nansen net (250 µm mesh size) in pre- and post-winter conditions in 2015/2016. In December, the coastal copepod community was limited over the western flank, while epipelagic waters of the open and eastern waters were characterized by high diversity, low abundances in the central area, and subsurface/upper mesopelagic copepod species. In April, higher abundances were recorded over the entire vertical profile with the surface coastal copepod community present through the entire transect. Higher abundances in the central area during the post-winter period are probably a consequence of late-winter/early spring blooms near the center of the Southern Adriatic. Mesopelagic fauna of both months was characterized by high abundances of Haloptilus longicornis, characteristic species of the eastern Mediterranean, whose larger presence was favored by the cyclonic phase of the North Ionian Gyre and a consequent strong Levantine Intermediate Water ingression.

scholarly journals Tintinnid Ciliate Communities in Pre- and Post-Winter Conditions in the Southern Adriatic Sea (NE Mediterranean)

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2329 ◽  
Author(s):  
Jakica Njire ◽  
Mirna Batistić ◽  
Vedrana Kovačević ◽  
Rade Garić ◽  
Manuel Bensi
Keyword(s):  
Adriatic Sea ◽  
Sea Water ◽  
Dynamic Environment ◽  
Intermediate Water ◽  
The North ◽  
Winter Conditions ◽  
Winter Convection ◽  
Oceanic Species ◽  
Physical Forces ◽  
The Impact

The Southern Adriatic Sea is a dynamic region under the influence of diverse physical forces that modify sea water properties as well as plankton dynamics, abundance, and distribution in an intricate way. The most pronounced being: winter vertical convection, lateral exchanges between coastal and open sea waters, and the ingression of water masses of different properties into the Adriatic. We investigated the distribution and abundance of tintinnid species in this dynamic environment in pre- and post-winter conditions in 2015/2016. A strong ingression of the saline Levantine Intermediate Water, supported by the cyclonic mode of the North Ionian Gyre in 2015 and 2016, in December was associated with a high diversity of oceanic species. An unusual spatial distribution of neritic-estuarine species Codonellopsis schabi was observed in deeper layers along the analyzed transect, which emphasizes the strong influence of physical processes on deep water biology in the South Adriatic. A shift of population toward greater depths (mesopelagic) and modification of deep sea community structure was recorded in April as a consequence of the winter convection-driven sinking of tintinnids. Our findings indicate that tintinnid abundance and composition is heavily influenced by physical conditions and they are good indicators of the impact of physical forces, including climate changes, on marine environment.

scholarly journals Observation, Preconditioning and Recurrence of Exceptionally High Salinities in the Adriatic Sea

2021 ◽  
Vol 8 ◽  
Author(s):  
Hrvoje Mihanović ◽  
Ivica Vilibić ◽  
Jadranka Šepić ◽  
Frano Matić ◽  
Zrinka Ljubešić ◽  
...  
Keyword(s):  
High Salinity ◽  
Eastern Mediterranean ◽  
Heat Fluxes ◽  
Late Winter ◽  
Intermediate Water ◽  
Surface Salinity ◽  
Near Surface ◽  
Winter Convection ◽  
Dry Conditions ◽  
Forecasting System

The paper aims to describe the preconditioning and observations of exceptionally high salinity values that were observed in summer and autumn of 2017 in the Adriatic. The observations encompassed CTD measurements carried out along the well-surveyed climatological transect in the Middle Adriatic (the Palagruža Sill, 1961–2020), Argo profiling floats and several glider missions, accompanied with satellite altimetry and operational ocean numerical model (Mediterranean Forecasting System) products. Typically, subsurface salinity maximum, with values lower than 39.0, is observed in the Southern Adriatic (usually between 200 and 400 m), related to ingressions of saltier and warmer waters originating in the eastern Mediterranean (Levantine Intermediate Water—LIW). However, seasonally strong inflow of warm and high salinity waters (S > 38.8) has been observed much closer to the surface since spring 2015. The main LIW core deepened at the same time (to 400–700 m). Such double-maxima vertical pattern was eventually disturbed by winter convection at the beginning of 2017, increasing salinities throughout the water column. A new episode of very strong inflow of high salinity waters from the Northern Ionian was observed in late winter and spring of 2017, this time restricted almost to the surface. As most of 2017 was characterized by extremely dry conditions, low riverine inputs and warmer than usual summer over the Adriatic and Northern Ionian, salinity values above the sharp and shallow (15–40 m) thermocline significantly increased. The maximum recorded salinity was 39.26, as measured by the Argo float in the Southern Adriatic. Surface salinity maximum events, but with much lower intensity, have been documented in the past. Both past events and the 2017 event were characterized by (i) concurrence with overall high salinity conditions and cyclonic or transitional phase of the Adriatic-Ionian Bimodal Oscillating System, (ii) very low river discharges preconditioning the events for a year or more, (iii) higher-than-average heat fluxes during most of the summer and early autumn periods, forming a stable warm layer above the thermocline, and (iv) higher-than-average E-P (evaporation minus precipitation) acting on this warm surface layer. Importantly, the 2017 event was also preceded by strong near-surface inflow of very saline waters from the Northern Ionian in early 2017.

scholarly journals The Exceptionally Warm Winter of 2015/16 in Alaska

2017 ◽  
Vol 30 (6) ◽  
pp. 2069-2088 ◽  
Author(s):  
John E. Walsh ◽  
Peter A. Bieniek ◽  
Brian Brettschneider ◽  
Eugénie S. Euskirchen ◽  
Rick Lader ◽  
...  
Keyword(s):  
Atmospheric Circulation ◽  
Climate Models ◽  
Climate Model ◽  
Cold Season ◽  
Early Spring ◽  
Winter Period ◽  
Late Winter ◽  
Albedo Effect ◽  
Climate Model Simulations ◽  
Height Fields

Abstract Alaska experienced record-setting warmth during the 2015/16 cold season (October–April). Statewide average temperatures exceeded the period-of-record mean by more than 4°C over the 7-month cold season and by more than 6°C over the 4-month late-winter period, January–April. The record warmth raises two questions: 1) Why was Alaska so warm during the 2015/16 cold season? 2) At what point in the future might this warmth become typical if greenhouse warming continues? On the basis of circulation analogs computed from sea level pressure and 850-hPa geopotential height fields, the atmospheric circulation explains less than half of the anomalous warmth. The warming signal forced by greenhouse gases in climate models accounts for about 1°C of the anomalous warmth. A factor that is consistent with the seasonal and spatial patterns of the warmth is the anomalous surface state. The surface anomalies include 1) above-normal ocean surface temperatures and below-normal sea ice coverage in the surrounding seas from which air advects into Alaska and 2) the deficient snowpack over Alaska itself. The location of the maximum of anomalous warmth over Alaska and the late-winter–early-spring increase of the anomalous warmth unexplained by the atmospheric circulation implicates snow cover and its albedo effect, which is supported by observational measurements in the boreal forest and tundra biomes. Climate model simulations indicate that warmth of this magnitude will become the norm by the 2050s if greenhouse gas emissions follow their present scenario.

Coping with darkness and low temperatures: foraging strategies in Steller's eiders, Polysticta stelleri, wintering at high latitudes

2001 ◽  
Vol 79 (3) ◽  
pp. 402-406 ◽  
Author(s):  
Geir Helge Systad ◽  
Jan Ove Bustnes
Keyword(s):  
Low Temperatures ◽  
Early Spring ◽  
The Other ◽  
Foraging Strategies ◽  
Winter Period ◽  
Late Winter ◽  
Feeding Time ◽  
High Latitudes ◽  
Late Autumn ◽  
Polysticta Stelleri

To examine how Steller's eiders, Polysticta stelleri, wintering at 70°N cope with adverse winter conditions in terms of darkness and low temperatures, we studied their feeding behaviour during four periods between late autumn and early spring. Steller's eiders were most likely to feed during daylight and twilight, but they also fed during darkness. The incidence of feeding was highest at low tide, and there was a significant interaction between tidal cycle and winter period. Hence, the birds fed more intensively at low tide in midwinter (January) than during the other periods. Air temperatures were between 8 and 10°C lower in midwinter than during the other periods, and during this period the eiders also fed more by means of nondiving techniques (up-ending, surface feeding). The total estimated feeding time was highest in late autumn and midwinter (5.9 and 6.3 h were spent actively feeding, respectively) and lower in late winter and spring (5.1 and 4.6 h, respectively). Thus, as energy requirements increased as a result of low temperatures, Steller's eiders increased their feeding effort, but also reduced feeding costs by reducing diving depth. The results of this study suggest that the Steller's eider is behaviourally well adapted to survive winter at high latitudes at relatively low stress.

The relationship between the atmospheric variability and productivity in the Adriatic Sea area

2009 ◽  
Vol 89 (8) ◽  
pp. 1549-1558 ◽  
Author(s):  
Branka Grbec ◽  
Mira Morović ◽  
Gordana Beg Paklar ◽  
Grozdan Kušpilić ◽  
Slavica Matijević ◽  
...  
Keyword(s):  
Primary Production ◽  
Adriatic Sea ◽  
Eastern Mediterranean ◽  
Regional Scale ◽  
Thermocline Depth ◽  
Intermediate Water ◽  
Atmospheric Variability ◽  
Test Analysis ◽  
Sea Temperature ◽  
Production Variability

Interannual variability of the primary production in the middle Adriatic Sea for the period 1961–2002 was examined and correlated to the various atmospheric and oceanographic parameters. The sequential t-test analysis of regime shift (STARS) method and locally-weighted scatter plot smoothing (LOWESS) method were applied to the primary production, revealing the new regime with significantly different mean productivity ranging from 1980–1996. Moreover, this period with the highest primary production, consists of the two distinguished sub-periods: periods of increasing (1980–1986) and decreasing (1987–1996) primary production. Whereas in the first period the ecosystem was under the influence of warmer and nutrient richer Levantine Intermediate Water (LIW) intrusions into the Adriatic, in the second period, which started with a cold winter in 1987, the Eastern Mediterranean Transient (EMT) occurred. The EMT established a new circulation regime which prevented the LIW intrusions in the Adriatic, causing its reduced productivity. Reduced LIW inflow in the Adriatic was evidenced in the lower than normal sea temperature, salinity and oxygen concentrations below the thermocline depth. Precipitation and wind regime also arose as important local factors for the primary production variability. Our analysis connected the shifts in primary production with hemispheric and regional scale climate variations, and supports the hypothesis that atmospheric variability can trigger the ecosystem changes.

scholarly journals Hydrography in the Mediterranean Sea during a cruise with RV <i>POSEIDON</i> in April 2014

2015 ◽  
Vol 8 (1) ◽  
pp. 427-446
Author(s):  
D. Hainbucher ◽  
V. Cardin ◽  
G. Siena ◽  
U. Hübner ◽  
M. Moritz ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Adriatic Sea ◽  
Eastern Mediterranean ◽  
Intermediate Water ◽  
Strait Of Gibraltar ◽  
Eastern Mediterranean Sea ◽  
German Research ◽  
The Mediterranean ◽  
Long Term Variations

Abstract. We report on data from an oceanographic cruise in the Mediterranean Sea on the German research vessel POSEIDON in April 2014. Data were taken on a west–east section starting at the Strait of Gibraltar and ending south-east of Crete as well on sections in the Ionian and Adriatic Sea. The objectives of the cruise were twofold; long-term variations of the Levantine Intermediate Water (LIW) and the deep water masses of the Eastern Mediterranean Sea were investigated. The measurements include salinity, temperature, oxygen and currents and were conducted with a CTD/rosette system, an underway CTD and an ADCP. The sections are on tracks which have been sampled during several other cruises, thus supporting the opportunity to investigate the long term temporal development of the different variables. The use of an underway CTD made it possible to conduct measurements of temperature and salinity with a high resolution of 6 nm and a vertical resolution of 1 dbar for the upper 800 m of the water column.

Phytoplankton distribution related to different winter conditions in 2016 and 2017 in the open southern Adriatic Sea (eastern Mediterranean)

2021 ◽  
pp. 103665
Author(s):  
Nenad Jasprica ◽  
Marijeta Čalić ◽  
Vedrana Kovačević ◽  
Manuel Bensi ◽  
Iris Dupčić Radić ◽  
...  
Keyword(s):  
Adriatic Sea ◽  
Eastern Mediterranean ◽  
Phytoplankton Distribution ◽  
Winter Conditions

scholarly journals PROGRESS MADE WITH PARAQUAT IN RELATION TO PASTURE MANAGEMENT

1969 ◽  
pp. 96-109
Author(s):  
P.P. Williams ◽  
P.C. Palmer
Keyword(s):  
Growth Rates ◽  
Dry Matter ◽  
Early Spring ◽  
Farm Management ◽  
Winter Period ◽  
Late Winter ◽  
Pasture Management ◽  
Matter Production ◽  
Lamb Growth ◽  
Clover Content

Spraying pasture with paraquat in spring or summer at rates of 1 to 4 oz/acre increased the clover content during the first summer and was followed by strong recovery of ryegrass during the autumn/ winter period. Trials have indicated increased dry matter production from treated pasture imn late winter/early spring. Lamb growth rates were significantly higher on sprayed pasture, especially during the summer to autumn period. The implications of these effects are discussed in relation to farm management.

scholarly journals A Climatological Assessment of Intense Desert Dust Episodes over the Broader Mediterranean Basin Based on Satellite Data

2021 ◽  
Vol 13 (15) ◽  
pp. 2895
Author(s):  
Maria Gavrouzou ◽  
Nikolaos Hatzianastassiou ◽  
Antonis Gkikas ◽  
Christos J. Lolis ◽  
Nikolaos Mihalopoulos
Keyword(s):  
Mediterranean Basin ◽  
Eastern Mediterranean ◽  
Mean Value ◽  
Early Spring ◽  
Dust Aerosol ◽  
Ozone Monitoring Instrument ◽  
Central Mediterranean ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer

A satellite algorithm able to identify Dust Aerosols (DA) is applied for a climatological investigation of Dust Aerosol Episodes (DAEs) over the greater Mediterranean Basin (MB), one of the most climatologically sensitive regions of the globe. The algorithm first distinguishes DA among other aerosol types (such as Sea Salt and Biomass Burning) by applying threshold values on key aerosol optical properties describing their loading, size and absorptivity, namely Aerosol Optical Depth (AOD), Aerosol Index (AI) and Ångström Exponent (α). The algorithm operates on a daily and 1° × 1° geographical cell basis over the 15-year period 2005–2019. Daily gridded spectral AOD data are taken from Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua Collection 6.1, and are used to calculate the α data, which are then introduced into the algorithm, while AI data are obtained by the Ozone Monitoring Instrument (OMI) -Aura- Near-UV aerosol product OMAERUV dataset. The algorithm determines the occurrence of Dust Aerosol Episode Days (DAEDs), whenever high loads of DA (higher than their climatological mean value plus two/four standard deviations for strong/extreme DAEDs) exist over extended areas (more than 30 pixels or 300,000 km2). The identified DAEDs are finally grouped into Dust Aerosol Episode Cases (DAECs), consisting of at least one DAED. According to the algorithm results, 166 (116 strong and 50 extreme) DAEDs occurred over the MB during the study period. DAEDs are observed mostly in spring (47%) and summer (38%), with strong DAEDs occurring primarily in spring and summer and extreme ones in spring. Decreasing, but not statistically significant, trends of the frequency, spatial extent and intensity of DAECs are revealed. Moreover, a total number of 98 DAECs was found, primarily in spring (46 DAECs) and secondarily in summer (36 DAECs). The seasonal distribution of the frequency of DAECs varies geographically, being highest in early spring over the eastern Mediterranean, in late spring over the central Mediterranean and in summer over the western MB.

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