Strait Of Gibraltar Research Articles

The Rising Concern for Sea Level Rise: Altimeter Record and Geo-Engineering Debate

The Oceans from Space V Symposium, held in Venice, Italy, on 24–27 October 2022, devoted special sessions to sea level rise, as described by a series of satellite altimeters, and to remediations of consequent calamities in vulnerable mediterranean seas. It emerged that various aspects of climate change can be modelled in time as a Single Exponential Event (SEE), with a similar trend (a 54–year e–folding time) for CO2 concentration in the Earth’s atmosphere, global average sea surface temperature, and global average sea level. The sea level rise record, combining tide gauges data starting in 1850, as well as more recent altimeter data, for the last 30 years, is already 25 cm above historical values. If the curve continues to follow the exponential growth of the simple SEE model, it will reach about 40 cm by the year 2050, 1 m by 2100, and 2.5 m by 2150. As a result, dramatic impacts would be expected for most coastal areas in the next century. Decisive remediations, based on geo-engineering at the basin scale, are possible for semi-enclosed seas, such as the Mediterranean and Black Seas. Damming the Strait of Gibraltar would provide an alternative to the conclusion that coastal sites such as the City of Venice are inevitably doomed.

The Moriscos of Salé and the Hispanic Monarchy: Power Agents and Identities to the West of the Strait of Gibraltar, 1631–1632

AbstractThis article examines the multiple frontiers between Maghrebi Islam and the southern European Catholic world by focusing on a very specific episode during the struggle for control of Rabat, capital of present-day Morocco. It addresses the problem of military and political control of the Strait of Gibraltar, which was closely linked to widespread corsair raids in the early seventeenth century. It also examines moriscos’ attempts to be allowed to return to Spain. The article points to the key importance of intermediaries and their linkages across borders at a time when both the Hispanic Monarchy and the Sa’adi kingdom were undergoing great difficulties. The strategic importance of the region transformed moments of crisis into opportunities, albeit failed ones, as intermediaries articulated their own interests with those of the king of Spain.

Project of artisanal fisheries management in the proposed marine protected area of Jbel Moussa (Morocco)

Artisanal fisheries are the subject of a growing interest in the conservation community. It is considered as a less harmful extractive activity in many multiple-use marine protected areas (MPAs)s. However, only a few of these MPAs have been able to successfully combine their nature conservation objectives with those of managing artisanal fisheries in a sustainable manner. In many cases, the artisanal fishing activity and the communities related to it have been barely involved in the management of MPAs, which has led to sometimes tense situations between fishermen and MPA managers. This work takes the example of the future marine protected area "Jbel Moussa", located in northern Morocco just off the Strait of Gibraltar, where artisanal fishing is one of the main local activities. A survey was conducted between July and November 2022 and targeted the future stakeholders of the marine protected area. Knowing already the point of view of the artisanal fishermen of Jbel Moussa from previous works, this survey has served to clarify the perspective of the future managers of the protected area, in order to take stock of all that is planned in terms of the general management of the site and artisanal fisheries, but also to determine if there is a real communication between each stakeholder category. After analysis, the results of the survey showed some shortcomings in communication between the different categories of actors interviewed, but also some divergence of opinions between the managers of the future protected area and the artisanal fishermen operating there. However, it was revealed that several projects addressing, in particular, some of the aspects studied in this work, are being carried out at the site and will undoubtedly allow the problems observed to be taken into account for a better future management of the MPA.

Discovering Appearance of the Franks in Arab Sources (8th–9th Centuries)

At the time of Crusades, the term “franks” (ifranj) was common Arabic word for the crusaders. Since that, almost any study of the Crusades from the “Islamic perspective” tends to discover francs in Arab sources. However, medieval Muslim authors mentioned the Franks since the early 9th century, long before the Crusades, but nobody asks when and how Arabic authors actually learn about the Franks. There is still a half-century-old hypothesis by B. Lewis, attributing the word “franc” (faranj) to the Greek “fráŋkos”. The aim of our article is to discover the original source from which the Arabs first learn about the Franks, so we study the 9th-century Arab texts reporting on the first known contact between Arabs and Franks during the Muslim conquest of Spain. It seems that the Arabic faranj could hardly originate from the Greek fráŋkos, as the combination of letters <γκ> sounds as <nk> during this period (which corresponds to another Arabic form firank appearing in a number of texts in 11th–12th centuries and not widely used). That is why the Arabic franc could actually originate from Syriac as a transcription of the Syriac prangāiā. Based on message of the 9th-century historian Ibn Kutaiba we suppose that Arabs learned this term from the Syrian sailors who ensured the crossing of Muslim army through the Strait of Gibraltar in the spring of 711.

Tying up loose ends together: Cetaceans, maritime traffic and spatial management tools in the Strait of Gibraltar

Abstract The transboundary area of the Strait of Gibraltar is home to seven protected cetacean species that are threatened by high intensity of maritime traffic. More comprehensive knowledge of cetaceans and maritime traffic is required, together with analyses of legislations, strategies and policies. This study quantitatively investigates cetacean distribution and maritime traffic intensity and, for the species of community interest bottlenose dolphin, habitat suitability. Results are qualitatively discussed considering the overlap of cetacean hot spots with different maritime activities and the consistency of spatial conservation management measures in force. The Fixed Line Transect Mediterranean Monitoring Network protocols were followed for 59 visual surveys using ferries as observation platforms for monitoring cetaceans and maritime traffic. Surveys were carried out along the transects between Algeciras and Ceuta and between Algeciras and Tanger‐Med, in 2018 and 2019. 264 cetacean sightings, including seven different species and four near‐miss collision events (involving pilot, sperm and fin whales), were reported. Monitoring cetaceans from ferries in the Strait provided insights into cetacean distribution and maritime traffic, enabling the identification of cetacean hot spots, suitable habitats and maritime traffic high‐risk zones. A transboundary management effort is required, together with an adaptive approach for protecting highly mobile species such as cetaceans. Proposals include a long‐term cetacean monitoring program carried out by dedicated observers on board ferries as a cost‐effective methodology and mandatory training for crew members, to increase cetacean knowledge and reduce collision risk. The designation of an international temporal or, in some zones, permanent speed reduction area (i.e., Cetacean Critical Navigation Zone, with a maximum speed of 13 knots) and of a micro‐sanctuary with a seasonal no‐take zone in the Bay between Algeciras and Gibraltar, together with international surveillance, are recommended measures for the enhancement of conservation efforts in the Strait.

The Pliocene succession of Lyon Metropolis (SE France): an overfill of a Messinian incised-valley

The Pliocene ria, a narrow seaway running up the Rhône Valley, has been mapped for a while by field geologists. Only much later, after the DSDP Leg 13 in 1970, a consensus was reached that this unique geological feature of the Rhône Valley was created by the major Mediterranean sea-level drop associated with the Messinian Salinity Crisis, followed by a sudden sea-level rise caused by the breach of the Strait of Gibraltar and the invasion of the Mediterranean Basin by the Atlantic waters. At the regional level of the Lyon Metropolis in the upper Rhône Valley, main issues were however remaining about the course and depth of the Messinian valley, and about the valley fill, namely where and how do the Pliocene marine strata of the Rhône Valley pass to the continental deposits of the Bresse Basin to the north? These are key-questions in that the Plio-Pleistocene makes up a large fraction of the basement that holds up a large city, not free from potential geological hazards and subject to problems of groundwater management, high-cost tunneling projects, etc. Our survey reviews first the historical researches − descriptions of the outcrops and fossil assemblages. It is followed by an unprecedented analysis and correlation of a thousand boreholes, which makes it possible to physically link and reconcile ancient local observations. Sections across the Messinian valley reveal a proper canyon morphology for the segments that cut the crystalline basement. The magnitude of the incision has been calculated as 335 m to a minimum, three hundred kilometers away from the river mouth. Three major depositional systems are distinguished for the Pliocene − Lower Pleistocene succession. The valley that initially ran much farther north of Lyon was occupied in the Zanclean by a series of pounded lakes, dammed by transverse local alluvial fans, filled by minor Gilbert-type deltas, and repeatedly flooded by marine ingressions. The valley wings were then encroached during the Piacenzian by a major, Alps-rooted alluvial sheet. At the level of Lyon, the fluvial deposits were deflected to the north (Sables de Trévoux) and to the south (Alluvions jaunes) as a dichotomy. The succession was then capped by a gravel-dominated fluvio-glacial fan (Alluvions jaunes sommitales) at the Plio-Pleistocene transition. It spread out from the north-east to the south, and intersected the previous valley overfill due to the shift to the north, i.e., South Jura, of the feeder stream. The depositional and current elevations of the marine-influenced episodes, i.e. marker bands that punctuate the regional Neogene succession, are used to bring out successive uplift and subsidence phases of the region. Finally, we tentatively link the major shifts in the depositional patterns of the Late Neogene succession in the Lyon area to major changes in the thrust belt activity, exhumation story, and outset of glaciers in the western Alps.

The non-consumptive economic value of wildlife: the case of three cetacean species

The conservation of wildlife is one of the most pressing issues in the current times, but wildlife conservation economic values have often been largely ignored due to an absence of market prices, as setting an economic value on biodiversity or whole ecosystems can be challenging. Nevertheless, valuing wildlife can be of great significance to improve decision-making in the conservation field, as it can provide a complementary perspective based on economic principles. Whale-watching provides an opportunity for the economic valuation of wildlife. Specifically, it offers a framework in which the economic revenue allows the economic valuation of the targeted cetaceans to be estimated through the direct and indirect expenditure of the tourists who purchase whale-watching tours. Here, we performed an economic analysis based on population abundances of the three main species targeted by the whale-watching companies in the Strait of Gibraltar (Spain): long-finned pilot whales (Globicephala melas), common dolphins (Delphinus delphis) and killer whales (Orcinus orca). These species generated a total annual income of €4,089,056, €1,876,833, and €505,389, respectively, and each individual would generate an average of €14,048, €951, and €36,099 each year, respectively. Incorporating life expectancy, this corresponded to a total population value of €112,426,185, €16,685,147, and €19,171,107, respectively, over their lifetime. These values provide an idea of the potential contribution of cetaceans to the local economy but only represent their non-consumptive value based on tourism. Our results reinforce the idea that a sustainable, high-quality whale-watching culture, under ACCOBAMS High-Quality Whale-Watching requirements, should be promoted to ensure a sustainable industry, stable economic income and the viability of cetacean populations in the Strait of Gibraltar.

Spatial Distribution and Potential Impact of Drifted Thalli of the Invasive Alga Rugulopteryx okamurae in Circalittoral and Bathyal Habitats of the Northern Strait of Gibraltar and the Alboran Sea

The arrival of a new invasive alga, Rugulopteryx okamurae, in the Strait of Gibraltar (SoG) in 2015 marked an unprecedented milestone in the North African and, later, in the European marine ecosystems. Nowadays, it is colonising vast infralittoral areas and significantly modifying some habitats and associated communities of the southern Iberian Peninsula. In recent expeditions, a high amount of free drifted thalli of this alga has been detected in different circalittoral and bathyal habitats of the northern SoG and the Alboran Sea. The present study combines quantitative data of this alga obtained with the use of a remotely operated vehicle (ROV) and a bottom otter trawl. The coverage–entanglement level of the drifted thalli on circalittoral and bathyal benthic invertebrates (e.g., not covering, covering only the basal part, covering one-third of the invertebrate, etc.) was also annotated from picture frames taken in locations with abundant drifted thalli. In underwater images, drifted thalli were mainly detected in circalittoral and bathyal bottoms of the northern SoG and the north-western Alboran Sea, between 50 to ca. 450 m depth. Nevertheless, abundant drifted thalli were also detected in bottom otter trawl samples from circalittoral bottoms of the north-central and north-eastern Alboran Sea. Small benthic organisms (e.g., encrusting sponges, hydrozoans, etc.) generally displayed low coverage–entanglement levels of drifted thalli. Nevertheless, large sessile and colonial benthic organisms with a complex three-dimensional morphology (e.g., gorgonians, colonial scleractinians) reached high levels of R. okamurae thalli entangled in different parts of their colonies. The drifted R. okamurae thalli entangled in these colonial suspension feeding organisms may hinder their feeding capability in the long term, resulting in habitat deterioration in the near future.

Seasonal dynamics and annual budget of dissolved inorganic carbon in the northwestern Mediterranean deep-convection region

Abstract. Deep convection plays a key role in the circulation, thermodynamics, and biogeochemical cycles in the Mediterranean Sea, which is considered to be a hotspot of biodiversity and climate change. In the framework of the DEWEX (Dense Water Experiment) project, the seasonal and annual budgets of dissolved inorganic carbon in the deep-convection area of the northwestern Mediterranean Sea are investigated over the period September 2012–September 2013 using a 3D coupled physical–biogeochemical–chemical modeling approach. At the annual scale, we estimate that the northwestern Mediterranean Sea's deep-convection region was a moderate sink of 0.5 mol C m−2 yr−1 of CO2 for the atmosphere. The model results show the reduction of oceanic CO2 uptake during deep convection and its increase during the abrupt spring phytoplankton bloom following the deep-convection events. We highlight the major roles in the annual dissolved inorganic carbon budget of both the biogeochemical and physical fluxes, which amount to −3.7 and 3.3 mol C m−2 yr−1, respectively, and are 1 order of magnitude higher than the air–sea CO2 flux. The upper layer (from the surface to 150 m depth) of the northwestern deep-convection region gained dissolved inorganic carbon through vertical physical transport and, to a lesser extent, oceanic CO2 uptake, and it lost dissolved inorganic carbon through lateral transport and biogeochemical fluxes. The region, covering 2.5 % of the Mediterranean, acted as a source of dissolved inorganic carbon for the surface and intermediate water masses of the Balearic Sea and southwestern Mediterranean Sea and could represent up to 22 % and 11 %, respectively, of the CO2 exchanges with the Atlantic Ocean at the Strait of Gibraltar.

Otolith-temperature estimates in Atlantic bluefin tuna (Thunnus thynnus) from the Mediterranean Sea: Insights from clumped isotope measurements

The subpopulation and/or contingent structure of Atlantic bluefin tuna (Thunnus thynnus) within the Mediterranean Sea is undefined, leading to uncertainty regarding the best strategy for an effective assessment and management of this highly exploited stock. This study aimed to reconstruct temperatures experienced by Atlantic bluefin tuna during the early life period (<3.5 months) using clumped isotope temperature proxy, an innovative geothermometer for carbonates, that does not require previous knowledge of other environmental parameters such as water oxygen composition. We examined otolith chemistry in fish captured from 3 different areas of the Mediterranean Sea and adjacent waters. We found that mean seasonal temperature estimates from clumped isotopes did not differ significantly from satellite derived and otolith oxygen stable isotopic ratios derived temperatures, except for the central Mediterranean Sea, were clumped isotopes derived temperatures were significantly higher than satellite derived temperatures. However, the sensitivity of the clumped isotope thermometer was found to be lower than that based on oxygen fractionation equation, with high variance observed in the clumped isotopes derived temperature estimates. We also observed that clumped isotope derived temperatures were undistinguishable among bluefin tuna captured in the Gibraltar Strait, the central, and eastern Mediterranean Sea. In this paper, we discuss the major sources of uncertainty in temperature reconstructions using bluefin tuna otoliths.

Dynamics of Atmospheric-Driven Surface Currents on The Gulf of Cadiz Continental Shelf and its link with The Strait of Gibraltar and The Western Alboran Sea

Several studies about the coastal circulation over the continental shelf of the Gulf of Cadiz have been published in the last twenty years. One of the most studied features in these papers are the so-called Coastal Counter Currents (CCCs) which are located roughly between the 100 m isobath and the coastline and are directed westwards. Despite the considerable number of articles devoted to the analysis of this phenomenon, the actual along-coast extension and origin of these CCCs currently remain unclear.In the present study, different mechanisms are proposed to explain the development of these CCCs. They have been revised and discussed taking into account the latest findings from a recent analysis that utilized surface currents derived from High Frequency Radar (HFR) as well as numerical model simulations. The most interesting finding is that the most intense CCCs events are initiated on the coastal margin of the westernmost side of the Strait of Gibraltar, and they are extended further west of Cape Santa Maria. Furthermore, these intense and extensive CCCs seem to be triggered by the joint action of local winds over the Gulf of Cadiz and additional remote effects which are coming from (i) the wind forcing over the Alboran Sea and the easternmost side of the Strait of Gibraltar, and (ii) the Sea Level Atmospheric Pressure forcing over the Ligurian Sea (western Mediterranean Sea). In addition, the same forcing mechanisms are valid to explain the eastward intensification of the coastal currents.The most relevant feature of the hydrodynamic pattern originated by this combination of forcing agents is its quasi-geostrophic adjustment against the coast in the whole spatial dominion. In addition, these results offer a clear example of how important the effects of forcing in rather remote regions may be in defining the hydrodynamic patterns of certain oceanographic regions.

Diversity and Phylogeny of Gyrodactylus spp. (Monogenea: Gyrodactylidae) across the Strait of Gibraltar: Parasite Speciation and Historical Biogeography of West Mediterranean Cyprinid Hosts

Knowledge on the diversity of parasitic flatworms of Western Mediterranean cyprinids is extremely scarce. In the present study, we parasitologically investigated 12 cyprinid species across the Strait of Gibraltar inhabiting watersheds in northwest Africa (Morocco) and Iberia (Portugal and Spain). Taxonomically relevant features of the attachment organ and sequences of the 18S rDNA and ITS regions were used for species delineation and to investigate their phylogenetic relatedness. Among the Gyrodactylus collected from Morocco and Spain, we identified specimens with an unusual T-shaped dorsal bar observed herein for the first time. In contrast, the membranous patch-like structure surrounding the twisted inner roots of hamuli and the median ridge of the ventral bar have been generally observed in Eurasian relatives. Our analyses suggest vicariant speciation of Gyrodactylus across the Strait of Gibraltar. We describe herein G. gibraltarensis sp. nov. from Iberian Luciobarbus graellsii; G. moroccensis sp. nov. from northwest African cyprinids, i.e., L. maghrebensis, L. rabatensis, L. rifensis, L. yahyaouii, and L. zayanensis; and finally, G. pseudomoroccensis sp. nov. from Moroccan L. ksibi, all possessing a new haptoral configuration. The genetic divergence and conservative morphologies in populations of G. moroccensis sp. nov. from five cyprinid species support its ongoing speciation in Northwest Africa. The West Mediterranean lineage was revealed to be monophyletic, with Eurasian species forming a sister group. Morphologically, West Mediterranean Gyrodactylus also appeared to be of Middle Eastern origin. Gyrodactylus spp. possessing an unusual T-shaped dorsal bar have most likely speciated, allowing for the appearance of a haptoral morphology that is restricted to the region across the Strait of Gibraltar. To conclude, viviparous Gyrodactylus reflect parasite speciation across the Strait of Gibraltar and the historical biogeography of cyprinids in the West Mediterranean.

Searching for Mediterranean bath sponges (Demospongiae: Dictyoceratida: Spongiidae) in the Northeast Atlantic reveals a new species: an integrative taxonomic approach

Abstract Bath sponges, included in the Spongiidae (Demospongiae: Dictyoceratida), are distributed across the oceans of the world, with a greater abundance in temperate, subtropical, and tropical zones. Their harvest started during ancient times in the Mediterranean Sea, which shed light on the whole family. Most of the Mediterranean Spongiidae have been reported repeatedly from the Northeast Atlantic, notably along the Iberian peninsula. The aim of this study was to clarify the taxonomic status of these sponges after a recent sampling effort in the French Pays Basque and the Spanish Cantabria, complemented by several Mediterranean Sea stations, including the Strait of Gibraltar. An integrative taxonomic approach was adopted for the first time on a set of Spongiidae samples from the Northeast Atlantic, assessing the congruence of analyses of: (i) the morphology of the spongin skeleton; (ii) two different parts of the genome (mitochondrial and nuclear); and (iii) metabolomic fingerprints, to delimit the frontiers between species better. A new bath sponge species is described herein, and significant advances and changes are proposed for the systematics of the family.

Statelessness and Nationality Matters in the context of Migration between Northern Africa and Spain

Abstract This article explores the problems linked with the determination of nationality and the condition of statelessness in a complex setting characterized by undocumented migration, such as the transit zone around the Strait of Gibraltar, between North Africa and the southern borders of Spain. The States immediately concerned are Morocco and Spain, although the situation affects many other neighbouring States in North Africa. The study suggests that without a precise mechanism to separate regimes between ordinary migrants and migrants who need international protection, such States fail to fulfil their international obligations regarding stateless persons and other undocumented migrants.

The time series at the Strait of Gibraltar as a baseline for long-term assessment of vulnerability of calcifiers to ocean acidification

The assessment of the saturation state (Ω) for calcium carbonate minerals (aragonite and calcite) in the ocean is important to determine if calcifying organisms have favourable or unfavourable conditions to synthesize their carbonated structures. This parameter is largely affected by ocean acidification, as the decline in seawater pH causes a decrease in carbonate ion concentration, which in turn, lowers Ω. This work examines temporal trends of seawater pH, ΩAragonite and ΩCalcite in major Atlantic and Mediterranean water masses that exchange in the Strait of Gibraltar: North Atlantic Central Water (NACW), Levantine Intermediate Water (LIW) and Western Mediterranean Deep Water (WMDW) using accurate measurements of carbonate system parameters collected in the area from 2005-2021. Our analysis evidences a gradual reduction in pH in the three water mases during the monitoring period, which is accompanied by a decline in Ω for both minerals. The highest and lowest decreasing trends were found in the NACW and LIW, respectively. Projected long-term changes of Ω for future increases in atmospheric CO2 under the IPCC AR6 Shared Socio-economic Pathway "fossil-fuel-rich development" (SSP5-8.5) indicate that critical conditions for calcifiers with respect to aragonite availability will be reached in the entire water column of the region before the end of the current century, with a corrosive environment (undersaturation of carbonate) expected after 2100.

In Situ Observations of the Small‐Scale Dynamics at Camarinal Sill—Strait of Gibraltar

AbstractRecently, PROTEVS GIB20 experiment was performed in the Strait of Gibraltar. Part of this experiment was dedicated to observe the high frequency dynamics near Camarinal Sill (CS), considered as a mixing hotspot in the region. Mooring lines equipped with current profilers and temperature/salinity probes provided data which evidence two dynamical regimes depending on the tidal current intensity; in neap tide floods, local internal hydraulic control is never observed over CS while in spring tide, local internal hydraulic control depicts a tide‐dependent and spatially variable pattern. In spring tide floods, measurements revealed the development of a hydraulic jump over the sill and its advection on the lee side. Cross sill sections with CTD casts and acoustic images confirmed this dynamics and depicted a well developed hydraulic jump on the eastern flank of the sill during spring tide ebbs. The north‐south and temporal variability of the internal hydraulics was analyzed from several zonal sections over CS, the mean topographic feature of the Strait of Gibraltar. We highlighted a complex series of local hydraulic jumps constrained by topography and a significant north‐south variability. The spatiotemporal variability of local hydraulics questions the two dimensional representation of the exchange flow in the Strait of Gibraltar. During neap tide flood, the dynamics of the Mediterranean outflow was investigated from a fixed station. We imaged the development of instabilities at the interface between Atlantic and Mediterranean waters jointly with the generation of much thicker billows deeper. Finally, we discuss our findings in relation to other straits dynamics.

Injuries in cetaceans in the Strait of Gibraltar: an update for the period 2016-2020

The Strait of Gibraltar is an important habitat for seven regularly occurring cetacean species. These waters are heavily used for fishing and therefore experience extraordinary levels of shipping traffic. Photography provides a valuable and non‐invasive tool to monitor the health of cetacean populations, where external injuries may indicate specific anthropogenic impacts, such as vessel strikes or fishery interactions. We manually screened 27,866 photos taken during whale‐watching operations between 2016–20 for human‐induced injuries. Injuries of potential anthropogenic origin were detected in 228 cases. The severity of these injuries ranged from superficial linear marks to severe traumas that may affect survival and fitness. Severe injuries included a gunshot wound, vessel‐related traumata and abrasions, signs of previous severe entanglements and deep lacerations which could stem from recreational fishery activities or propellor cuts and occasionally served as an entry point for dermal infections. In 2007, Spanish legislation introduced regulations on how to approach cetaceans by boat, but recreational fishery vessels have been commonly observed to disregard this law. We therefore urge stricter control and enforcement of existing laws and collaboration between the Spanish and Moroccan authorities to mitigate the human impact on cetaceans in this region. KEYWORDS: CETACEANS, STRAIT OF GIBRALTAR, HUMAN IMPACT, WOUNDS, LACERATIONS, ENTANGLEMENTS

Water Masses of the Mediterranean Sea and Black Sea: An Overview

This overview presents the different water masses present in the various primary and secondary marine regions of the Mediterranean Sea and Black Sea, providing information on their main physical characteristics (i.e., temperature, salinity, density), the water depths at which they have been observed and the processes involved in their formation. There is a characteristic difference in the overall hydrology of the Mediterranean Sea compared to the Black Sea, in terms of the number and characteristics of water masses and their formation processes, although they form a single (integrated) marine system. This difference is explained by the limited communication between the two seas through the Sea of Marmara and its straits (the Dardanelles and Bosporus) and by the fact that the Mediterranean Sea is a condensation basin while the Black Sea is a dilution basin; therefore, the deficit of water in the former is compensated by the inflow of Atlantic waters, while the surplus in the latter outflows to the Aegean Sea. In total, 21 different water masses have been identified in the Mediterranean Sea (excluding the Straits of Gibraltar and the Sea of Marmara) compared to the 5 water masses identified in the Black Sea (excluding the Sea of Azov). This large number of water masses is attributed to coastal morphology (i.e., presence of straits) and submarine relief (i.e., deep basin separated by shallow sills) and different formation processes.

Skin conditions, epizoa, ectoparasites and emaciation in cetaceans in the Strait of Gibraltar: An update for the period 2016-2020.

ABSTRACT: Cetacean populations in the Strait of Gibraltar are heavily impacted by human activities. Photographs are a valuable tool to monitor the external health of cetaceans. We visually screened 27,866 pictures taken during whale watching operations in the years 2016–2020 for abnormal conditions, such as emaciation, dermal diseases and epizoic infestations. Prevalence levels could not be calculated as data were obtained opportunistically. Dermal diseases were detected in 566 sightings and occurred in all species. Bottlenose dolphins were most strongly affected (n = 192). Hypopigmented skin lesions were most common in all species (n = 291). Tattoo skin disease‐like lesions affected 16 animals (T. truncatus: n = 12; G. melas: n = 3; D. delphis: n = 1). Other observed conditions include expansive annular lesions in three juvenile pilot whales. Furthermore, we report the presence of open wounds in 28 animals (G. melas: n = 23; T. truncatus: n = 2; P. macrocephalus: n = 3). In three pilot whales, these wounds did not heal over a period of several years. Epizoic and ectoparasitic infestations include the observation of Xenobalanus spp. and Pennella balaenopterae. Multiple fin whales were sighted with very high numbers of Pennella balaenopterae, ranging up to 84 parasites per host. Emaciation was mainly detected in bottlenose dolphins (n = 36) and seemed to affect these animals more severely during specific years, potentially indicating fluctuations in prey availability. KEYWORDS: CETACEANS; DERMAL DISEASES; EMACIATION; ECTOPARASITES; STRAIT OF GIBRALTAR

Soil erosion and hydroclimatic hazards in major African port cities: the case study of Tangier

Land degradation and soil erosion are becoming increasingly problematic in Africa's rapidly developing urban areas, particularly in Major Port Cities. Uncontrolled expansion and human pressures are hindering planning, adaptation, and conservation efforts. To understand the extent of these issues, this study combined morphometric analysis, soil loss calculation, field monitoring, and remote sensing and GIS tools to assess soil erosion in the Metropolis of Tangier (Morocco) located at the confluence of the Mediterranean Sea and the Atlantic Ocean at the Strait of Gibraltar. The study relied on data from 13 rain gauge stations, official reports, and remote sensing acquisitions, as well as field observations. Results showed an average soil erosion rate of 24.2 t/ha/year, equivalent to an annual soil loss of 588,051 t/year. This high rate was largely due to areas with a high erosion risk (99.8%), covering only 8.3% of the territory, which were characterized by recently burned topsoil, fallow land, and steep slopes. These areas included both uncontrolled neighbourhoods and areas for planned urban and industrial expansion, posing a threat to the landscape's sustainability and socio-economic prospects. The morphometric analysis revealed its high vulnerability to erosion and degradation, with the highest soil loss rates observed in the eastern and western regions. The study also found that flash floods caused by hydroclimatic hazards can lead to significant damage to infrastructure and equipment, particularly in western sub-basins and mountainous regions. In conclusion, the use of remote sensing and GIS technologies provided valuable insights into the physical characteristics and vulnerability of the Tangier Metropolis to land degradation and soil erosion. These findings emphasize the need for effective land management practices and conservation measures to mitigate the impacts of land degradation and soil erosion in the face of climate change. This information is crucial for decision-makers and stakeholders to develop strategies to address these pressing issues.