Strait Of Gibraltar

Background The impact of shipping emissions on urban agglomerations close to major ports and vessel routes is probably one of the lesser understood aspects of anthropogenic air pollution. Little research has been done providing a satisfactory comprehension of the relationship between primary pollutant emissions, secondary aerosols formation and resulting air quality. Materials and methods In this study, multi-year (2003–2007) ambient speciated PM10 and PM2.5 data collected at four strategic sampling locations around the Bay of Algeciras (southern Spain), and positive matrix factorisation model were used to identify major PM sources with particular attention paid to the quantification of total shipping emissions. The impact of the emissions from both the harbour of Algeciras and vessel traffic at the Western entrance of Mediterranean Sea (Strait of Gibraltar) were quantified. Ambient levels of V, Ni, La and Ce were used as markers to estimate PM emitted by shipping. Results and discussion Shipping emissions were characterised by La/Ce ratios between 0.6 and 0.8 and V/Ni ratios around 3 for both PM10 and PM2.5. In contrast, elevated La/Ce values (1–5) are attributable to emissions from refinery zeolitic fluid catalytic converter plant, and low average V/Ni values (around 1) result mainly from contamination from stainless steel plant emissions. The direct contribution from shipping in the Bay of Algeciras was estimated at 1.4–2.6 μg PM10/m3 (3–7%) and 1.2–2.3 μg PM2.5/m3 (5–10%). The total contribution from shipping (primary emissions + secondary sulphate aerosol formation) reached 4.7 μg PM10/m3 (13%) and 4.1 μg PM2.5/m3 (17%).

In the present study we have analyzed 44 Y-chromosome biallelic polymorphisms in population samples from northwestern (NW) Africa and the Iberian Peninsula, which allowed us to place each chromosome unequivocally in a phylogenetic tree based on >150 polymorphisms. ...

The Mediterranean-Black Sea system consists of two semi-enclosed basins connected by the Turkish Straits. In turn, the Mediterranean Sea is connected to the Atlantic Ocean through the narrow Strait of Gibraltar. The hydrological cycle of the system is driven by fresh water exchanges between the atmosphere, continents and oceans, and by salty water mass exchange among the ocean basins. Monitoring such water fluxes, especially its time evolution, is essential to understand the water cycle in the region, which is very sensitive to global climate changes and influences the variability of the Atlantic Meridional Overturning Circulation (AMOC), which in turn affects the global climate. In this study, we have estimated the hydrological cycle of the Mediterranean-Black Sea system from the time-variable gravity observations performed by the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On satellites, and precipitation and evaporation from ERA5 atmospheric reanalysis data for the period 2002-2020. In the Black Sea, rivers introduce an average water volume of 391 ± 12 km 3 /year, one third of which escape through the atmosphere and two thirds go to the Mediterranean Sea. In the latter, 1787 ± 23 km 3 /year are lost via net evaporation. The rivers runoff (502 ± 27 km 3 /year), and the inflow of Atlantic waters (1020 ± 56 km 3 /year; 0.0323 ± 0.0018 Sv), finally restore the Mediterranean water budget. The balance is not reached instantaneously, and this delay introduces a seasonal variability in all the fluxes. In particular, the net water flux from the Atlantic Ocean increases up to 2660 ± 111 km 3 /year in August/September, and reverses to − 407 ± 140 km 3 /year in April/ May. On top of the climatology, the mean annual Atlantic water flux varies significantly between 706 and 1262 km 3 /year.

The response of coccolithophore assemblages to short-term millennial and centennial climatic changes over the last 50 kyr is studied in core M39029-7 from the Gulf of Cadiz (Atlantic Ocean) and core MD95-2043 from the Alboran Sea (Western Mediterranean Sea). The nannoplankton data are compared with oxygen isotopes, U37k′-SST and other biogeochemical and sedimentological proxies to obtain a new perspective of the paleoceanography and paleoecology of the area during these short-term climatic changes. Coccolithophores indicate that Heinrich events (HE) were characterised by the presence of cold, low salinity and turbid water masses on both sides of the Strait of Gibraltar. High abundances of the Lower Photic Zone (LPZ) species Florisphaera profunda in the Gulf of Cadiz synchronous with HE are interpreted as being an evidence of upper water-column stratification on the Atlantic side. These episodes coincided with input of terrigenous material, especially during H2. Surface waters during Dansgaard-Oeschger (DO) Stadials were also cold and turbid, while most of DO Interstadials were characterised by warm-water flora. The increase in small placoliths (small Gephyrocapsa and Emiliania huxleyi (<4 μm)) reveals a higher coccolithophore production during DO Interstadials and the Holocene. Conversely, HE and most of DO Stadials show peaks of E. huxleyi (>4 μm), which is considered here as a cold-water indicator. The sharp decrease in large specimens of E. huxleyi related to the warming trend in the last deglaciation can be used as a biostratigraphic reference level that marks—at least approximately—the deglaciation and the beginning of the Holocene. Peaks of F. profunda are observed during Termination 1 (T1) in the Alboran Sea. They are isochronous with the “Organic-Rich Layer 1” recognised in the Western Mediterranean. In this interval, the water column of the region was stratified as a consequence of the global increase in the sea level following the deglaciation. Quantitative analyses of the coccolithophore assemblage allow us to interpret that coccolithophore production has been higher in the Alboran Sea than in the Gulf of Cadiz during the Holocene.

SUMMARY Although there have been several studies of the migratory movements of Atlantic bluefin tuna (Thunnus thynnus, L.) between the Western and Eastern Atlantic, the two-stock hypothesis remains untested and exchange rates are still unidentified. TUNASAT, an EU-funded research programme involving Italy, Spain, Greece and the UK, which was carried out during the three- year period 1998-2000 in the Mediterranean Sea and the Strait of Gibraltar, and a subsequent tagging program funded by the Italian Ministry of Agriculture and Forestry Policies, which was carried out during 2003 in the Eastern Mediterranean, aimed to better understand this problem. Both bluefin tuna tagging programs were executed using pop-up satellite tags. Results from both tagging programs indicated that adults &lt; 100 kg remain in Mediterranean after spawning and feed in areas of high primary productivity, as indicated by SeaWiFS satellite data for chlorophyll-a concentration. After spawning large bluefin 150-2...

We have made a comparative analysis of dental morphometries of theMegantereonspecimens found in the Lower Pleistocene site at Venta Micena (Orce, Granada, Southeastern Spain) with representatives of the genus throughout the Old and New World. The methodologies used in the study include discriminant functions and principal component analysis. The results obtained point to the presence of three distinct species of this genus:M. cultridens(Cuvier), indigenous to North America from the Lower Pliocene onwards, which in the Indian subcontinent gave rise to the larger sized speciesM. falconeriPomel during the Upper Pliocene.M. cultridenssurvived until the Middle Pleistocene in China, and its African descendantM. whiteiBroom colonized Europe at the time of the Plio-Pleistocene boundary, reaching Dmanisi via the Near East and southern part of the Iberian Peninsula at Venta Micena via the Strait of Gibraltar.

Recent observations of the outflowing Mediterranean water collected near the bottom in key points of the Strait of Gibraltar show the existence of a seasonal cycle with warmer and lighter waters leaving the Mediterranean Sea in winter and cooler and denser waters in spring early summer. The amplitude of the signal is around 5 10-2 °C for potential temperature and 1.5 10-2 for potential density, salinity hardly showing seasonal fluctuations. The outflow also shows a seasonal cycle with maximum volume transport in April, in coincidence with the minimum of the signal of potential temperature. A simple analysis of the composition of the outflow in terms of the main water masses of the western Mediterranean basin and its comparison with climate indicators suggests that the seasonal cycle follows the annual process of the Western Mediterranean Deep Water formation that replenish the deep portion of the basin by the end of winter and rises the level of the deep water reservoir, facilitating the suction of cooler and denser water from the Mediterranean over the sills of the Strait. From this time onwards, the data show a smooth warming that would be explained by the progressive fall of the level of the Western Mediterranean Deep Water as it is drained out the Mediterranean, which would leave warmer water available for suction. The process is asymmetric in the sense that the transition from high to low temperature is completed in a short period while the progressive warming spans a longer period.

Sequence data of the mitochondrial cytochrome b gene of stripe-necked terrapins (Mauremys leprosa) have been compared from localities north and south of the Atlas Mts . (Ceuta; Morocco) and from Donana National Park (Spain). A low maximum sequence divergence (approximately I %) corresponds to two major clades; one is re presented by localities to the north of the Atlas Mts.

The study of more than 500 single- and multichannel
seismic records enabled the generation of a detailed
palaeo-bathymetric map of the Messinian surface over most
of the Alboran Basin, Western Mediterranean. This regional
surface is characterized by several erosional features
(channels, terraces and canyons) and topographic highs
(structural, volcanic and diapiric in origin). The most
prominent feature is the incised Zanclean Channel crossing
the entire basin, its entrenchment having been associated
with the opening of the Strait of Gibraltar and subsequent
inflow of Atlantic waters. The incision depth of the channel is
variable, suggesting local variations in the erosive capacity of
the Atlantic inflow, conditioned mainly by the regional basin
topography and the local presence of topographic highs.
Adjacent to this channel along the Spanish and Moroccan
margins, and near the Strait of Gibraltar, several submarine
terraces developed at different depths suggest a pulsed
flooding of the Alboran Basin. There could have been two
major inflow phases of Atlantic water, one shortly before and
another during the Zanclean flooding, the latter accompanied
by periods of relative sea-level stillstands that enabled terrace
development. Alternatively, these features were all generated
during the main flooding evident and subsequent pulsed
infilling of the basin.

1Wind power plants represent a risk of bird mortality, but the effects are still poorly quantified. We measured bird mortality, analysed the factors that led birds to fly close to turbines, and proposed mitigation measures at two wind farms installed in the Straits of Gibraltar, one of the most important migration bottlenecks between Europe and Africa.2Bird corpses were surveyed along turbine lines and an associated power line to estimate mortality rates. The behaviour of birds observed within 250 m of turbines was also recorded as a putative indicator of risk. The effects of location, weather and flight behaviour on risk situations (passes within 5 m of turbines) were analysed using generalized linear modelling (GLM).3Mortality caused by turbines was higher than that caused by the power line. Losses involved mainly resident species, mostly griffon vultures Gyps fulvus (0·15 individuals turbine−1 year−1) and common kestrels Falco tinnunculus (0·19 individuals turbine−1 year−1). Mortalities were not associated with either structural attributes of wind farms or visibility.4Vulture collisions occurred in autumn–winter and were aggregated at two turbine lines where risks of collisions were greatest. The absence of thermals in winter forced vultures to use slopes for lift, the most likely mechanism influencing both their exposure to turbines and mortality.5Kestrel deaths occurred during the annual peak of abundance in summer. Carcasses were concentrated in the open habitats around a single wind farm and risk may have resulted from hunting habitat preferences.6Synthesis and applications. We conclude that bird vulnerability and mortality at wind power facilities reflect a combination of site-specific (wind–relief interaction), species-specific and seasonal factors. Despite the large number of migrating birds in the study area, most follow routes that are displaced from the facilities. Consequently, only a small fraction of birds on migratory flights was actually exposed to turbines. New wind installations must be preceded by detailed behavioural observation of soaring birds as well as careful mapping of migration routes.Wind power plants represent a risk of bird mortality, but the effects are still poorly quantified. We measured bird mortality, analysed the factors that led birds to fly close to turbines, and proposed mitigation measures at two wind farms installed in the Straits of Gibraltar, one of the most important migration bottlenecks between Europe and Africa.Bird corpses were surveyed along turbine lines and an associated power line to estimate mortality rates. The behaviour of birds observed within 250 m of turbines was also recorded as a putative indicator of risk. The effects of location, weather and flight behaviour on risk situations (passes within 5 m of turbines) were analysed using generalized linear modelling (GLM).Mortality caused by turbines was higher than that caused by the power line. Losses involved mainly resident species, mostly griffon vultures Gyps fulvus (0·15 individuals turbine−1 year−1) and common kestrels Falco tinnunculus (0·19 individuals turbine−1 year−1). Mortalities were not associated with either structural attributes of wind farms or visibility.Vulture collisions occurred in autumn–winter and were aggregated at two turbine lines where risks of collisions were greatest. The absence of thermals in winter forced vultures to use slopes for lift, the most likely mechanism influencing both their exposure to turbines and mortality.Kestrel deaths occurred during the annual peak of abundance in summer. Carcasses were concentrated in the open habitats around a single wind farm and risk may have resulted from hunting habitat preferences.Synthesis and applications. We conclude that bird vulnerability and mortality at wind power facilities reflect a combination of site-specific (wind–relief interaction), species-specific and seasonal factors. Despite the large number of migrating birds in the study area, most follow routes that are displaced from the facilities. Consequently, only a small fraction of birds on migratory flights was actually exposed to turbines. New wind installations must be preceded by detailed behavioural observation of soaring birds as well as careful mapping of migration routes.