scholarly journals The Larval Stages of Portumnus (Crustacea Brachyura) with Notes On Some Other Genera

1944 ◽  
Vol 26 (1) ◽  
pp. 7-15 ◽  
Author(s):  
Marie V. Lebour
Keyword(s):  
Marine Fauna ◽  
Larval Stages ◽  
North East ◽  
The North ◽  
Fine Gravel ◽  
Crab Stage

Two species of Portumnus occur in the Plymouth area, P. biguttatus (Risso) and P. latipes (Pennant). P. biguttatus was the only species recorded when the old fauna list of Plymouth was published (1904), but since then it is known that P. latipes is very common in certain sandy areas (see Plymouth Marine Fauna, 1931), far commoner than P. biguttatus.P. biguttatus is rare and has not been seen since 1906. It was first found by W. Garstang and R. Todd on Drake's Island in Plymouth Sound, burrowing in fine gravel (1905), and two specimens, and are recorded from a sandy patch from the north-east corner of Drake's Island. A female in berry was recorded from the same locality by R. Todd, and L. R. Crawshay dredged one in Cawsand Bay in 1906. Apparently the eggs were not hatched out and the zoea of this species is unknown. In August 1902 R. Gurney obtained a megalopa in the plankton and from it secured the first crab stage. He describes the megalopa as being intensely blue. The cast skin of the megalopa and the crab obtained from it (Fig. 3a-c), which he kindly handed to me, are described in my paper of 1928 (Lebour, 1928c, p. 518, pl. viii, figs. 1–3). There is no reason to doubt the accuracy of the determination, especially because, as shown below, corresponding stages of P. latipes as well as the zoeae are now known and are very distinct, differing considerably from those of P. biguttatus.

A review of the biology of European cockles (Cerastodermaspp.)

2012 ◽  
Vol 92 (7) ◽  
pp. 1563-1577 ◽  
Author(s):  
Shelagh K. Malham ◽  
Thomas H. Hutchinson ◽  
Matt Longshaw
Keyword(s):  
Future Climate Change ◽  
Future Research ◽  
Climate Change Scenarios ◽  
Larval Biology ◽  
Important Species ◽  
Larval Stages ◽  
North East ◽  
The North ◽  
Wide Range ◽  
Few Data

This review examines the biology of the two main cockle speciesCerastoderma eduleandC. glaucumfound in coastal areas around the north-east Atlantic from Norway to Morocco and through the Baltic, Mediterranean and Black Sea. It considers those factors in particular that impact on the overall health and survival of individuals as well as populations. Methods for the discrimination of the species are reviewed as well as the approaches being taken to delineate different populations, which is crucial to appropriately manage individual fisheries. Cockle populations generally undergo sexual maturation during their second summer and sexes are separate. Eggs are pelagic, with larvae being both benthic and pelagic before settling on the sediment and becoming benthic adults. However, data are lacking on basic larval biology and dispersal mechanisms. Data are provided on predator–prey relationships including information on types of food of importance to cockles. Main predators of cockles include brown shrimp, shore crabs, gastropods, polychaetes, fish and a variety of birds and these can be important in structuring cockle populations. Predation of larval cockles by adult cockles through larviphagy can lead to reductions of up to 40% of the population. Cockles are sensitive to a wide range of chemical contaminants but few data are published on impacts on cockles, in particular larval stages. The review concludes with an assessment of future climate change scenarios on cockles and considers some areas of future research required to preserve this ecologically and economically important species.

scholarly journals The boundary between the Middle Eocene Brussel Sand and the Lede Sand Formations in the Zaventem-Nederokkerzeel area (Northeast of Brussels, Belgium)

2001 ◽  
Vol 3 (3-4) ◽  
pp. 231-255 ◽  
Author(s):  
Jacques HERMAN ◽  
Etienne STEURBAUT ◽  
Noël VANDENBERGHE
Keyword(s):  
Sea Level ◽  
Middle Eocene ◽  
Fine Sand ◽  
Calcareous Nannofossil ◽  
Relative Sea Level ◽  
Marine Fauna ◽  
North East ◽  
The North ◽  
Shark Teeth ◽  
Large Channel

In the Zaventem airport railway cutting, to the north-east of Brussels, the upper part of the Brussel Sand Formation consists of two major units, both attributable to calcareous nannofossil zone NP14a. The lower predominantly sandy unit ZB1 (including subunits A, B and C, belonging to NP14al) is built up of sparsely glauconitic, relatively coarse tidal current deposits with nodule levels cemented by carbonate and silica, of which one shows slumping structures and is interpreted as a seismite. The uppermost unit ZB2 (also labelled D, belonging to NP14a2), composed of alternating thin fine sandstone bands and silty marls, represents the fill of a large channel. In the Berg-Nederokkerzeel sandpit the carbonate-rich Brussel Sand Formation is finer grained and more homogeneous. Here, the basal sand (unit A) is attributable to NP14a3 and consequently, younger than the section exposed at Zaventem. It is incised at its the top by a rather narrow erosive gully, filled in with well-sorted fine sand rich in washed-in molluscs (unit B), some of which seem to point to a brackish influence. The extreme top is made up of half a meter of sand with abundant Callianassa burrows and echinid fragments (unit C). From the nannofossil data it appears that, east of Brussels, at least two generations of tidal channel systems seem to have occurred within the Brussel Sand Formation, followed by a partial emersion at the end of the filling of the uppermost channel (Nederokkerzeel B). This was succeeded by a relative sea-level rise, as shown by unit C and the remains of a completely eroded fully marine deposit, reworked in the base of the overlying Lede Sand Formation. The lowest relative sea level, with at least partial emergence of the Brussels area, occurred during middle to late Biochron NP14b. In both outcrops the Lede Sand Formation displays its characteristic pale grey relatively fine-grained homogeneous nature with a stone layer near its base. It can be concluded that, at the beginning of the "Lede transgression", an erosion of older deposits, containing already lifhified stone layers, occurred. This was, apparently, at least locally, caused by storms, which could redistribute, imbricate and turn over the stones, explaining their bio-perforation on both sides. Afterwards the stones have been above water for a relatively long time, enough to allow the dissolution of the perforating organisms and consequently an important oxidation of their surfaces. These stones have subsequently been colonised by a new marine fauna. Part of the shark teeth and calcareous nannofossil assemblages found in the coarse base of the Lede Sand is definitely older than the taxa normally found in the Lede Sand Formation. These fossils are the remains of a sediment package, believed to represent the formerly "Laekenian" stage.

Ras al Khaimah: further archaeological discoveries

Antiquity ◽  
1976 ◽  
Vol 50 (200) ◽  
pp. 216-222
Author(s):  
Beatrice De Cardi
Keyword(s):  
United Arab Emirates ◽  
The State ◽  
Focused Attention ◽  
North East ◽  
The North ◽  
History Of ◽  
The City

Ras a1 Khaimah is the most northerly of the seven states comprising the United Arab Emirates and its Ruler, H. H. Sheikh Saqr bin Mohammad al-Qasimi, is keenly interested in the history of the state and its people. Survey carried out there jointly with Dr D. B. Doe in 1968 had focused attention on the site of JuIfar which lies just north of the present town of Ras a1 Khaimah (de Cardi, 1971, 230-2). Julfar was in existence in Abbasid times and its importance as an entrep6t during the sixteenth and seventeenth centuries-the Portuguese Period-is reflected by the quantity and variety of imported wares to be found among the ruins of the city. Most of the sites discovered during the survey dated from that period but a group of cairns near Ghalilah and some long gabled graves in the Shimal area to the north-east of the date-groves behind Ras a1 Khaimah (map, FIG. I) clearly represented a more distant past.

Lichens in the North-East regions of Cyprus

1999 ◽  
Vol 110 (5-6) ◽  
pp. 455-463 ◽  
Author(s):  
S. Güvenç ◽  
Ş Öztürk
Keyword(s):  
North East ◽  
The North

TBE in Italy

2019 ◽  
Author(s):  
Valentina Tagliapietra ◽  
Flavia Riccardo ◽  
Giovanni Rezza
Keyword(s):  
Case Series ◽  
East Part ◽  
Mountainous Regions ◽  
North East ◽  
The North ◽  
Tick Borne Encephalitis ◽  
Low Incidence

Italy is considered a low incidence country for tick-borne encephalitis (TBE) in Europe. Areas at higher risk for TBE in Italy are geographically clustered in the forested and mountainous regions and provinces in the north east part of the country, as suggested by TBE case series published over the last decade.

TBE in Italy

2020 ◽  
Keyword(s):  
Surveillance System ◽  
Ad Hoc ◽  
National Level ◽  
Case Series ◽  
Incidence Rates ◽  
Mountainous Regions ◽  
North East ◽  
The North ◽  
Tick Borne Encephalitis ◽  
Low Incidence

Italy is considered a low-incidence country for tick-borne encephalitis (TBE) in Europe.1 Areas at higher risk for TBE in Italy are geographically clustered in the forested and mountainous regions and provinces in the north east part of the country, as suggested by TBE case series published over the last decade.2-5 A national enhanced surveillance system for TBE has been established since 2017.6 Before this, information on the occurrence of TBE cases at the national level in Italy was lacking. Both incidence rates and the geographical distribution of the disease were mostly inferred from endemic areas where surveillance was already in place, ad hoc studies and international literature.1

The influence of submesoscale eddies on hydrochemical parameters and structural and functional characteristics of phytoplankton in the north-eastern part of the Black Sea

2019 ◽  
pp. 24-40
Author(s):  
Sergey B. Kuklev ◽  
Vladimir A. Silkin ◽  
Valeriy K. Chasovnikov ◽  
Andrey G. Zatsepin ◽  
Larisa A. Pautova ◽  
...  
Keyword(s):  
Anticyclonic Eddy ◽  
The Black Sea ◽  
Hydrochemical Parameters ◽  
North East ◽  
The North ◽  
Seasonal Thermocline ◽  
North Eastern ◽  
Quantitative Indicators ◽  
The City ◽  
North Eastern Part

On June 7, 2018, a sub-mesoscale anticyclonic eddy induced by the wind (north-east) was registered on the shelf in the area of the city of Gelendzhik. With the help of field multidisciplinary expedition ship surveys, it was shown that this eddy exists in the layer above the seasonal thermocline. At the periphery of the eddy weak variability of hydrochemical parameters and quantitative indicators of phytoplankton were recorded. The result of the formation of such eddy structure was a shift in the structure of phytoplankton – the annual observed coccolithophores bloom was not registered.

Engineering-Geological Studies Of The Territory, Soils Of Foundation And Foundations Of The Architectural Monument Of The "Melnikov’s House" In Moscow

2019 ◽  
pp. 41-51
Keyword(s):  
Working Condition ◽  
Overlying Water ◽  
North East ◽  
The North ◽  
Geological Processes ◽  
Architectural Monument ◽  
Geological Conditions ◽  
Zone Of Influence ◽  
Complex Engineering ◽  
Building Engineering

On the basis of engineering and design surveys of the building, engineering-geological and geophysical studies of the soils of the territory conducted by the article authors, as well as with due regard for the results of studies conducted on this territory by other authors, the features of the foundations, soils of their foundation and engineering-geological conditions of the territory of the Melnikov House are established. It is shown that the Melnikov house is located under complex engineering-geological conditions on the territory of high geological risk, in the zone of influence of tectonic disturbance. To the North of the area there is a zone of intersection of the observed disturbance with a larger disturbance that can have an impact on geological processes. To the North-East of the site of the Melnikov House, a sharp immersion of the roof of carbon deposits was revealed. It promotes groundwater seepage into limestone of the carbonate strata from overlying water-bearing sands and activation of processes of suffusion removal and sinkhole phenomena of the soil. The surveyed area is assessed as potentially karst-hazardous and adjacent to it from the North-East territory as karst-dangerous. In this regard any construction on the adjacent territory can provoke activation of sinkhole phenomena on the surface. The foundations of the building are basically in working condition. Existing defects can be eliminated during repair. The foundation soils mainly have sufficient bearing capacity. Areas of the base with bulk soil can be reinforced. However, when developing a project for the reconstruction of the building and its territory, it should be taken into account that the design of the Melnikov House does not provide for its operation on the loads at the formation of sinkholes.

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