scholarly journals Ovarian dynamics, batch fecundity and spawning phenology of the lessepsian migrant Etrumeus golanii DiBattista, Randall & Bowen, 2012 (Clupeidae: Dussumieriinae)

2021 ◽  
Vol 22 (3) ◽  
pp. 466
Author(s):  
STYLIANOS SOMARAKIS ◽  
MARIA GIANNOULAKI ◽  
KONSTANTINOS MARKAKIS ◽  
KOSTAS TSIARAS ◽  
EUDOXIA SCHISMENOU ◽  
...  
Keyword(s):  
Seasonal Cycle ◽  
Eastern Mediterranean ◽  
Germinal Vesicle ◽  
Western Mediterranean ◽  
Early Summer ◽  
Biogeochemical Model ◽  
Breeding Period ◽  
Batch Fecundity ◽  
Frequency Distributions ◽  
Final Maturation

The Golani’s round herring Etrumeus golanii is an Erythraean small pelagic fish (lessepsian migrant) that entered into the Mediterranean Sea through the Suez Canal. It has expanded its distribution from the east to the western Mediterranean with well-established local populations. We investigated basic aspects of its reproductive biology off the island of Crete (eastern Mediterranean) using ovarian histology and analysis of oocyte size-frequency distributions. The species exhibited a protracted breeding period (winter to early summer), with all ovaries examined during the main spawning season having markers of recent (postovulatory follicles, POFs) or imminent spawning (advanced oocyte batch in germinal vesicle migration or hydration). The advanced batch (AB) increased rapidly in size and was fully separated from the remainder, less developed oocytes in 95% of females with “old” POFs (POFs with signs of degeneration) and all females in final maturation. The growth of the subsequent batch (SB) was arrested at sizes <630 µm until full maturation of the AB. Mean diameter of hydrated oocytes ranged from 1181 to 1325 µm and relative batch fecundity was low ranging from 56 to 157 eggs g-1. The simulation of a coupled hydrodynamic/biogeochemical model (POM/ERSEM) provided evidence that E. golanii takes advantage of the seasonal cycle of planktonic production to reproduce and exhibits monthly changes in batch fecundity that appear to be closely related with the seasonal cycle of mesozooplankton concentration.     

scholarly journals Deep chlorophyll maximum and nutricline in the Mediterranean Sea: emerging properties from a multi-platform assimilated biogeochemical model experiment

2021 ◽  
Author(s):  
Anna Teruzzi ◽  
Giorgio Bolzon ◽  
Laura Feudale ◽  
Gianpiero Cossarini
Keyword(s):  
Mediterranean Sea ◽  
Satellite Data ◽  
Positive Impact ◽  
Model Simulation ◽  
Eastern Mediterranean ◽  
Western Mediterranean ◽  
Biogeochemical Model ◽  
Deep Chlorophyll Maximum ◽  
Argo Data ◽  
Chlorophyll Maximum

Abstract. Data assimilation has had a positive impact on biogeochemical modelling in a number of oceanographic applications. The recent operational availability of data from BGC-Argo floats, which provide valuable insights into key vertical biogeochemical processes, can lead to further improvements in biogeochemical modelling through assimilation schemes that include float observations in addition to traditionally assimilated satellite data. In the present work, we demonstrate the feasibility of joint multi-platform assimilation in realistic biogeochemical applications by presenting the results of one-year simulations of Mediterranean Sea biogeochemistry. Different combinations of satellite chlorophyll data and BGC-Argo nitrate and chlorophyll data have been tested, and validation with respect to available independent and semi-independent (before assimilation) observations showed that assimilation of both satellite and float observations outperformed the assimilation of platforms considered individually. Moreover, the assimilation of BGC-Argo data impacted the vertical structure of nutrients and phytoplankton in terms of deep chlorophyll maximum depth and intensity and nutricline depth. The outcomes of the model simulation assimilating both satellite data and BGC-Argo data have been used to explore the basin-wide differences in vertical features associated with summer stratified conditions, describing a relatively high variability between the western and eastern Mediterranean, with thinner and shallower but intense deep chlorophyll maxima associated with steeper and narrower nutriclines in the western Mediterranean.

scholarly journals Spatiotemporal variability of alkalinity in the Mediterranean Sea

2015 ◽  
Vol 12 (6) ◽  
pp. 1647-1658 ◽  
Author(s):  
G. Cossarini ◽  
P. Lazzari ◽  
C. Solidoro
Keyword(s):  
Mediterranean Sea ◽  
Seasonal Cycle ◽  
Sea Water ◽  
Eastern Mediterranean ◽  
Surface Flux ◽  
Spatiotemporal Variability ◽  
The Black Sea ◽  
Biogeochemical Model ◽  
Basin Scale ◽  
The Mediterranean

Abstract. The paper provides a basin-scale assessment of the spatiotemporal distribution of alkalinity in the Mediterranean Sea. The assessment is made by integrating the available observations into a 3-D transport–biogeochemical model. The results indicate the presence of complex spatial patterns: a marked west-to-east surface gradient of alkalinity is coupled to secondary negative gradients: (1) from marginal seas (Adriatic and Aegean Sea) to the eastern Mediterranean Sea and (2) from north to south in the western region. The west–east gradient is related to the mixing of Atlantic water entering from the Strait of Gibraltar with the high-alkaline water of the eastern sub-basins, which is correlated to the positive surface flux of evaporation minus precipitation. The north-to-south gradients are related to the terrestrial input and to the input of the Black Sea water through the Dardanelles. In the surface layers, alkalinity has a relevant seasonal cycle (up to 40 μmol kg−1) that is driven by physical processes (seasonal cycle of evaporation and vertical mixing) and, to a minor extent, by biological processes. A comparison of alkalinity vs. salinity indicates that different regions present different relationships: in regions of freshwater influence, the two quantities are negatively correlated due to riverine alkalinity input, whereas they are positively correlated in open sea areas of the Mediterranean Sea.

scholarly journals Deep chlorophyll maximum and nutricline in the Mediterranean Sea: emerging properties from a multi-platform assimilated biogeochemical model experiment

2021 ◽  
Vol 18 (23) ◽  
pp. 6147-6166
Author(s):  
Anna Teruzzi ◽  
Giorgio Bolzon ◽  
Laura Feudale ◽  
Gianpiero Cossarini
Keyword(s):  
Mediterranean Sea ◽  
Satellite Data ◽  
Model Simulation ◽  
Eastern Mediterranean ◽  
Western Mediterranean ◽  
Biogeochemical Model ◽  
Deep Chlorophyll Maximum ◽  
Argo Data ◽  
Chlorophyll Maximum ◽  
Consistent Picture

Abstract. Data assimilation has led to advancements in biogeochemical modelling and scientific understanding of the ocean. The recent operational availability of data from BGC-Argo (biogeochemical Argo) floats, which provide valuable insights into key vertical biogeochemical processes, stands to further improve biogeochemical modelling through assimilation schemes that include float observations in addition to traditionally assimilated satellite data. In the present work, we demonstrate the feasibility of joint multi-platform assimilation in realistic biogeochemical applications by presenting the results of 1-year simulations of Mediterranean Sea biogeochemistry. Different combinations of satellite chlorophyll data and BGC-Argo nitrate and chlorophyll data have been tested, and validation with respect to available independent non-assimilated and assimilated (before the assimilation) observations showed that assimilation of both satellite and float observations outperformed the assimilation of platforms considered individually. Moreover, the assimilation of BGC-Argo data impacted the vertical structure of nutrients and phytoplankton in terms of deep chlorophyll maximum depth, intensity, and nutricline depth. The outcomes of the model simulation assimilating both satellite data and BGC-Argo data provide a consistent picture of the basin-wide differences in vertical features associated with summer stratified conditions, describing a relatively high variability between the western and eastern Mediterranean, with thinner and shallower but intense deep chlorophyll maxima associated with steeper and narrower nutriclines in the western Mediterranean.

scholarly journals Parasites of the head of Scomber colias (Osteichthyes: Scombridae) from the western Mediterranean Sea

2014 ◽  
Vol 59 (1) ◽  
Author(s):  
Salvatore Mele ◽  
Maria Pennino ◽  
Maria Piras ◽  
José Bellido ◽  
Giovanni Garippa ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Eastern Mediterranean ◽  
Western Mediterranean ◽  
Parasite Fauna ◽  
Point Of View ◽  
Published Data ◽  
Multivariate Techniques ◽  
Western Mediterranean Sea ◽  
Scomber Colias ◽  
Non Parametric

AbstractThe metazoan parasite assemblage of the head of 30 specimens of the Atlantic chub mackerel (Scomber colias) from the western Mediterranean Sea was analysed. Eight species of parasites were found, four mazocraeid monogeneans: Grubea cochlear (prevalence = 10%), Kuhnia scombercolias (59%), K. scombri (52%), Pseudokuhnia minor (86%); three didymozoid trematodes: Nematobothrium cf. faciale (21%), N. filiforme (41%), N. scombri (7%); and one laerneopodid copepod: Clavelissa scombri (7%). Results were compared with previously published data from 14 localities of the eastern Mediterranean Sea and the Atlantic Ocean, using non-parametric univariate and multivariate analyses, and the whole parasite fauna of S. colias was compared with that of the congeners (S. australasicus, S. japonicus and S. scombrus). Parasites showed to reflect the biogeographical and phylogenetic history of host. From a methodological point of view, the use of both non-parametric univariate and multivariate techniques proved to be effective tools to detect dissimilarities between parasite assemblages.

scholarly journals Singing to Emmanuel: The Wall Paintings of Sant Miquel in Terrassa and the 6th Century Artistic Reception of Byzantium in the Western Mediterranean

Arts ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 128
Author(s):  
Carles Sánchez Márquez
Keyword(s):  
19Th Century ◽  
Eastern Mediterranean ◽  
Western Mediterranean ◽  
Wall Paintings ◽  
Singular Set ◽  
Late 19Th Century ◽  
Early Date ◽  
Early Christian ◽  
Christian Art ◽  
Technical Study

Since the late 19th century the wall paintings of Sant Miquel in Terrassa have drawn attention due to their singularity. From the early studies of Josep Puig i Cadafalch (1867–1956) to the present, both the iconographic program and the chronology of the paintings have fueled controversy among scholars. In particular, chronological estimates range from the time of Early Christian Art to the Carolingian period. However, a recent technical study of the paintings seems to confirm an early date around the 6th century. This new data allows us to reassess the question in other terms and explore a new possible context for the paintings. First, it is very likely that the choice of iconographic topics was related to the debates on the Arian heresy that took place in Visigothic Spain during the 5th and 6th centuries. Secondly, the paintings of Sant Miquel should be reconsidered as a possible reception of a larger 6th-century pictorial tradition linked to the Eastern Mediterranean, which is used in a very particular way. However, thus far we ignore which were the means for this artistic transmission as well as the reasons which led the “doers” of Terrassa to select such a peculiar and unique repertoire of topics, motifs, and inscriptions. My paper addresses all these questions in order to propose a new Mediterranean framework for the making of this singular set of paintings.

Caste Development and Its Seasonal Cycle in the Australian Harvester Termite, Drepanotermes Perniger (Froggatt) (Isoptera; Termitinae).

1974 ◽  
Vol 22 (4) ◽  
pp. 471 ◽  
Author(s):  
JAL Watson
Keyword(s):  
Seasonal Cycle ◽  
Early Summer ◽  
Fourth Instar ◽  
Northern Australia ◽  
The South ◽  
Worker Characteristics ◽  
Caste Development ◽  
Single Worker

The development of Drepanotermes perniger (Frogg.) in Australia is simple, with non-reproductive and reproductive lines separating at the first moult, a single worker line, a monomorphic soldier caste derived from two or three worker stages, and brachypterous neotenics formed by the premature metamorphosis of fifth-instar reproductive nymphs. Intercastes are known between soldier and fifth-instar reproductive nymph; presoldier and neotenic; and third-instar worker and fourth-instar reproductive nymph. All have substantially nymphal thoraces and abdomens, with minor intercaste modifications, and heads that are variously modified from nymphal towards soldier, presoldier or worker characteristics. The development of the castes shows a marked seasonal cycle, and only workers, soldiers and fourth-instar reproductive nymphs occur during the winter. Oviposition begins after the resumption of foraging in spring, and in the south growth and differentiation continue through much of the summer. Fourth-instar nymphs break diapause synchronously in early summer, and the alates fly with rains in January or February. In northern Australia there is a break in oviposition during summer, and the reproductive nymphs develop from eggs laid in autumn, after the alates have flown.

scholarly journals Effects of Ocean Biology on the Penetrative Radiation in a Coupled Climate Model

2006 ◽  
Vol 19 (16) ◽  
pp. 3973-3987 ◽  
Author(s):  
Patrick Wetzel ◽  
Ernst Maier-Reimer ◽  
Michael Botzet ◽  
Johann Jungclaus ◽  
Noel Keenlyside ◽  
...  
Keyword(s):  
Seasonal Cycle ◽  
Marine Biology ◽  
Climate Model ◽  
Global Climate ◽  
Ocean Model ◽  
Equatorial Pacific ◽  
Shortwave Radiation ◽  
Upper Ocean ◽  
Biogeochemical Model ◽  
Coupled Climate Model

Abstract The influence of phytoplankton on the seasonal cycle and the mean global climate is investigated in a fully coupled climate model. The control experiment uses a fixed attenuation depth for shortwave radiation, while the attenuation depth in the experiment with biology is derived from phytoplankton concentrations simulated with a marine biogeochemical model coupled online to the ocean model. Some of the changes in the upper ocean are similar to the results from previous studies that did not use interactive atmospheres, for example, amplification of the seasonal cycle; warming in upwelling regions, such as the equatorial Pacific and the Arabian Sea; and reduction in sea ice cover in the high latitudes. In addition, positive feedbacks within the climate system cause a global shift of the seasonal cycle. The onset of spring is about 2 weeks earlier, which results in a more realistic representation of the seasons. Feedback mechanisms, such as increased wind stress and changes in the shortwave radiation, lead to significant warming in the midlatitudes in summer and to seasonal modifications of the overall warming in the equatorial Pacific. Temperature changes also occur over land where they are sometimes even larger than over the ocean. In the equatorial Pacific, the strength of interannual SST variability is reduced by about 10%–15% and phase locking to the annual cycle is improved. The ENSO spectral peak is broader than in the experiment without biology and the dominant ENSO period is increased to around 5 yr. Also the skewness of ENSO variability is slightly improved. All of these changes lead to the conclusion that the influence of marine biology on the radiative budget of the upper ocean should be considered in detailed simulations of the earth’s climate.

scholarly journals Hydrography and Circulation West of Sardinia in June 2014

2017 ◽  
Author(s):  
Michaela Knoll ◽  
Ines Borrione ◽  
Heinz-Volker Fiekas ◽  
Andreas Funk ◽  
Michael P. Hemming ◽  
...  
Keyword(s):  
Eastern Mediterranean ◽  
Potential Temperature ◽  
Atlantic Water ◽  
Western Mediterranean ◽  
Anticyclonic Eddy ◽  
Intermediate Water ◽  
Potential Density ◽  
Sea Trial ◽  
The North

Abstract. In the mainframe of the REP14-MED sea trial in June 2014, the hydrography and circulation west of Sardinia, observed by means of gliders, shipborne CTD instruments, towed devices, and vessel-mounted ADCPs, are presented and compared with previous knowledge. So far, the circulation is not well known in this area, and the hydrography is subject to long-term changes. Potential temperature, salinity, and potential density ranges, as well as core values of the observed water masses were determined. Modified Atlantic Water (MAW), with potential density anomalies below 28.72 kg m−3, showed a salinity minimum of 37.93 at 50 dbar. Levantine Intermediate Water (LIW), with a salinity maximum of about 38.70 at 400 dbar, was observed within a range of 28.72 < σΘ [kg m−3] < 29.10. MAW and LIW showed slightly higher salinities than previous investigations. During the trial, LIW covered the whole area from the Sardinian shelf to 7°15' E. Only north of 40° N was it tied to the continental slope. Within the MAW, a cold and saline anticyclonic eddy was observed in the southern trial area. The strongest variability in temperature and salinity appeared around this eddy, and in the southwestern part of the domain, where unusually low saline surface water entered the area towards the end of the experiment. An anticyclonic eddy of Winter Intermediate Water was recorded moving northward at 0.014 m s−1. Geostrophic currents and water mass transports calculated across zonal and meridional transects showed a good agreement with vessel-mounted ADCP measurements. Within the MAW, northward currents were observed over the shelf and offshore, while a southward transport of about 1.5 Sv occurred over the slope. A net northward transport of 0.38 Sv across the southern transect decreased to zero in the north. Within the LIW, northward transport of 0.6 Sv across the southern transects were mainly observed offshore, and decreased to 0.3 Sv in the north where they were primarily located over the slope. This presentation of the REP14-MED observations helps to further understand the long-term evolution of hydrography and circulation in the Western Mediterranean, where considerable changes occurred after the Eastern Mediterranean Transient and the Western Mediterranean Transition.

scholarly journals Nonstationarity in Southern Hemisphere Climate Variability Associated with the Seasonal Breakdown of the Stratospheric Polar Vortex

2017 ◽  
Vol 30 (18) ◽  
pp. 7125-7139 ◽  
Author(s):  
Nicholas J. Byrne ◽  
Theodore G. Shepherd ◽  
Tim Woollings ◽  
R. Alan Plumb
Keyword(s):  
Climate Variability ◽  
Southern Hemisphere ◽  
Seasonal Cycle ◽  
Vortex Breakdown ◽  
Polar Vortex ◽  
Reanalysis Data ◽  
Early Summer ◽  
Stratospheric Polar Vortex ◽  
Time Symmetry

Abstract Statistical models of climate generally regard climate variability as anomalies about a climatological seasonal cycle, which are treated as a stationary stochastic process plus a long-term seasonally dependent trend. However, the climate system has deterministic aspects apart from the climatological seasonal cycle and long-term trends, and the assumption of stationary statistics is only an approximation. The variability of the Southern Hemisphere zonal-mean circulation in the period encompassing late spring and summer is an important climate phenomenon and has been the subject of numerous studies. It is shown here, using reanalysis data, that this variability is rendered highly nonstationary by the organizing influence of the seasonal breakdown of the stratospheric polar vortex, which breaks time symmetry. It is argued that the zonal-mean tropospheric circulation variability during this period is best viewed as interannual variability in the transition between the springtime and summertime regimes induced by variability in the vortex breakdown. In particular, the apparent long-term poleward jet shift during the early-summer season can be more simply understood as a delay in the equatorward shift associated with this regime transition. The implications of such a perspective for various open questions are discussed.

Amphoras in the Apollonia Museum Store

1981 ◽  
Vol 12 ◽  
pp. 75-78 ◽  
Author(s):  
John A. Riley
Keyword(s):  
Eastern Mediterranean ◽  
Eastern Mediterranean Region ◽  
Western Mediterranean ◽  
Second Century ◽  
Hellenistic Period ◽  
Royal Air Force ◽  
Agricultural Produce ◽  
Representative Selection ◽  
Coarse Wares ◽  
Selection Of

The store rooms of the Department of Antiquities at Apollonia contain pottery from excavations at Apollonia and Ras el Hilal, together with a few stray finds from other sites (including some from the sea collected by the Royal Air Force Aqualung Society in the 1950s and early 1960s). The bulk of this material dates in the later Roman period (i.e. sixth century A.D. onwards), but includes a little earlier Roman and some Hellenistic pottery. There is a representative selection of coarse wares, including amphoras, as yet unpublished. These are mainly in fragmentary condition but their typological range conforms with that from the well stratified and dated excavations at Berenice-Benghazi (Riley, in press).Publication of the more complete of these amphoras seems justified as there is a relative scarcity of published information on Roman amphoras from the eastern Mediterranean, at a time when many eastern types are being recognised in western Mediterranean excavated contexts (Panella, 1974; Hayes, 1976a; Riley, 1981). In addition, a brief consideration of the other amphoras helps to illustrate the diversity of trade in liquid agricultural produce within the eastern Mediterranean region. No locally made amphoras were noted on the Apollonia stone: all were imported into Cyrenaica.The Hellenistic period is represented by Rhodian (Inv. Nos. 321, 322 and 1582) and Knidian (Inv. Nos. 141 and 723) amphora fragments. There are several sherds of early Imperial amphoras, and attention has been drawn to these by Panella (1974). These include a first to second century A.D. Aegean type (ibid., 477, Ostia Form LXIII; Apollonia Box 2036, from Ras el Hilal); a Spanish garum amphora of the same period (ibid., 513, Ostia Form LXIII; Apollonia Inv. No. 256); several Tripolitanian amphoras of the first and second centuries A.D. (ibid., 562, Ostia Form LXIV; Apollonia Inv. Nos. 253, 254, 315 and 317); and a common Aegean amphora of the third and fourth centuries A.D. (ibid., 597, Ostia Form VI).

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