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The Aziza Cave, a major karstic cave in Morocco: biocorrosion and bat ethology

La Grotte Aziza, une cavité karstique majeure au Maroc : biocorrosion et éthologie des chiroptères
Lionel Barriquand, Philippe Audra, Hicham Benani, Larbi Boudad, Youssef Dbiba, Jean-Philippe Dégletagne, Fernando Gázquez, Vasile Heresanu, Samira Kaddouri, Soumia Moutaouakil, Ayoub Nehili, Lalla Amina Ouzzouit et Michel Renda

Résumés

La grotte Aziza est située dans le Haut Atlas, sur le plateau de Tazougart, province d'Er-Rachidia, au sud-est du Maroc. La cavité s’ouvre à environ 30 m au-dessus du lit de l’Oued Guir. Son point le plus profond est à 969 m d’altitude, pour une profondeur totale de 90 m et un développement de plus de 4 km. Elle est segmentée par plusieurs siphons. Les galeries situées avant les siphons ont un développement de plus de 1,3 km et présentent des morphologies variées et différentes de celles situées post-siphons. Située dans l’étage bioclimatique saharien, la grotte est occupée par plusieurs espèces de chiroptères qui y viennent en différentes saisons et y occupent spécifiquement certaines parties. Ainsi le peuplement de la cavité est sans cesse remodelé au cours de l’année. Les relevés topographiques et photogrammétriques effectués dans la grotte, croisés avec les observations sur les fréquentations de la cavité par les chiroptères, permettent de mettre en évidence le rôle de l’éthologie de ces animaux sur la biocorrosion. Plusieurs parties de la cavité montrent ainsi des formes spécifiques et des expansions importantes. Ces morphologies sont liées aux espèces qui fréquentent la grotte au printemps et en été et qui se regroupent en grandes colonies formant des essaims serrés. Il est également mis en évidence dans la grotte une minéralogie riche et variée liée à la présence de phosphates et de sulfates. L’hexahydrite, l’epsomite et la vivianite, connus à de rares occurrences en grotte, ont été identifiés à Aziza.

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Notes de la rédaction

reçu le 4 novembre 2025, définitivement accepté le 23 décembre 2025

Texte intégral

D. Borschneck (CEREGE, Aix-Marseille University) for mineralogical analyses using X-ray diffraction. Younes El Kharim, lecturer at the Faculty of Sciences in Tetouan, Department of Geology, who granted us access to the Technocentre to carry out mineralogical analyses. Yann Callot and Jacques Martini (†) for discussions on mineralogy and sediments. For the U/Th dating attempt, we thank the Institute of Geological Sciences of the Czech Academy of Sciences and the Polish Academy of Sciences (Warsaw, Poland). F.G. acknowledges the support of a Ramón y Cajal Fellowship from the Spanish AEI (RYC2020-029811-I) and the grant PPIT-UAL, JdA-FEDER 2022–2026 (RyC-PPI2021-01).

1. Introduction

1Caves are natural environments that, following their initial phreatic stage of formation, evolve over time in response to various environmental parameters, such as the establishment of specific ecosystems and climatic fluctuations. These evolutionary processes lead to morphological alterations affecting both the walls and the galleries, resulting from diverse weathering phenomena. Biocorrosion associated with bat activity has been extensively documented in several tropical regions where caves remain inhabited by large bat colonies and where corrosion processes are particularly active (Lundberg and MacFarlane, 2009, 2012, 2015; Bigot and Guyot, 2014; Dandurand et al., 2019; Farrant et al., 2025). From the mid-2010s onwards, several studies documented the presence of comparable inherited morphologies in numerous European caves that are no longer occupied by large bat colonies (Bigot, 2014; Audra et al., 2016; Bruxelles et al., 2016; Gély et al., 2018; Barriquand et al., 2021a; Bruxelles et al., 2024). Similar features have also been recognized in caves located in arid regions (Frumkin et al., 2018; Audra et al., 2021).

2Thus, the geomorphology of certain caves, or specific sections thereof, may reflect evidence of past occupation by bat colonies whose populations were far greater than those observed today. These studies have underscored the significant role of biogenic corrosion in the evolution of subterranean landscapes (Audra et al., 2016; Queffélec et al., 2018). In many cases, this process involves the alteration, and in some instances the complete disappearance, of components of the cave environment, including archaeological materials such as rock art (Bruxelles et al., 2016).

3Research based on the identification of characteristic corrosion morphologies and associated mineral deposits has revealed profound transformations in subterranean morphologies, accompanied by a marked retreat of cave walls. It has been demonstrated that the cross-sectional area of a cave can double solely as a consequence of prolonged occupation by bat colonies (Audra et al., 2016, 2021; Barriquand et al., 2021b).

4The ethological behavior of bats, along with the by-products of their activity (urine, guano, and respiratory exhalations), induces various types of alteration in the surrounding rock (Audra et al., 2019). These processes result from chemical reactions between acidic leachates derived from this organic waste and the calcium carbonate present in the host rock, speleothems, and sediments. On the cave walls and ceilings, alteration is primarily driven by dissolution caused by water acidified through CO2 released by bats. The limestone cement is progressively dissolved, and the remaining altered material becomes disaggregated and eventually detaches under the effect of gravity (Zupan Hajna, 2003), a process further facilitated by the repeated clinging of bats to the ceiling (Merino et al., 2019). This gradual disintegration of the roof can ultimately lead to a veritable “rain of sand” (Delaty et al., 2006). Three distinct corrosion processes can be identified on the cave walls: (i) the dissolution of carbonate minerals by acidified water flowing down the surfaces; (ii) the corrosive action of gaseous emissions on the walls (Farrant et al., 2025); and (iii) the reaction between calcium carbonate and phosphoric acid contained in leachates from guano deposits (Barriquand et al., 2024). These processes lead to the formation of phosphate minerals, predominantly members of the apatite group, which commonly appear as dark brown crusts. Within wall niches and floor fissures underlying guano accumulations, the action of phosphoric acid is particularly pronounced. On the cave floor, sedimentary deposits (David et al., 2018) and speleothems are likewise affected by biogenic corrosion (Audra et al., 2016). This alteration impacts not only the host rock and adjacent sediments but also any embedded archaeological materials (Shahack-Gross et al., 2004). Several studies have further demonstrated that bat guano contributes to the formation of specific mineralogical assemblages (Hill and Forti, 1997; Martini and Kavalieris, 1978; Audra et al., 2017, 2019, 2021).

5The order Chiroptera belongs to the class Mammalia and comprises approximately 1500 species (Simmons and Cirranello, 2025). Fossil evidence dating back between 52 and 47 million years has been discovered on the American, European, and African continents (Polturat, 2015; Rietbergen et al., 2023). Although chiropterans have successfully colonized all continents except the polar regions, their diversity reaches its highest levels in equatorial zones. For instance, more than 100 species have been reported in countries such as the Democratic Republic of the Congo, Kenya, and Cameroon (Van Cakenberghe and Seamark, 2023), whereas only 36 species are known from the entire European continent (Polturat, 2015), and 31 species in the whole Moroccan kingdom (Dbiba et al., 2025).

6Chiroptera commonly known as bats, exhibit considerable variation in body size, ranging from approximately 2 g in the smallest species (Craseonycteris thonglongyai, the bumblebee bat) to about 1.6 kg in the largest (Pteropus giganteus, the flying fox) (Dietz et al., 2009). They occupy a wide range of ecological niches and display diverse trophic adaptations, including insectivore, frugivore, nectarivore, piscivore, hematophagous, and carnivore (Brosset, 1966; Camacho et al., 2019). These volant and generally nocturnal mammals exploit a variety of habitats, such as buildings, trees, and both natural and artificial cavities. The use of these roosting sites may vary seasonally, particularly during mating, maternity, and hibernation periods (Rodrigues and Palmeirim, 2007).

7Many bat species exhibit strong site fidelity, regularly returning to the same cave across generations (Casteret, 1936; Entwistle et al., 2000; Furmankiewicz, 2016). Bats typically congregate in colonies, the size of which varies according to species and the type of activity. The largest colonies observed in a single cavity can exceed one million individuals. For example, at Eagle Creek Cave, Arizona, a colony of Tadarida brasiliensis

was estimated to number between 2 and 4 million individuals based on counts conducted between 1962 and 1991. The local density of this species was approximately 1500 adults or 4000 juveniles (less than 15 days old) per square meter (McCraken and Gustin, 1991). At Bracken Cave, Texas, colony size reaches an estimated 40 million individuals. In Kenya, bat densities of around 400 individuals per square meter have been reported, covering approximately 82 % of the cave ceiling (Lundberg and McFarlane, 2015). The presence of these colonies induces significant climatic alterations in their vicinity, including changes in temperature, condensation, CO2 emissions, and aerosols associated with excrement (Barriquand et al., 2021a; Zenon et al., 2024).

8To date, the impact of bats on cave geomorphology has been examined without accounting for the species present in the caves or their specific ethologies. However, due to differences between species, they must have different impacts on caves. The objectives of this study are, after (i) presenting the Aziza cave, (ii) identifying the bat species present and their occupancy patterns, ethology, and the spaces they occupy within the cave, (iii) to define the morphological characteristics of the different parts of the cave, and (iv ) to attempt establishing a relationship between species, ethology and associated geomorphology, in order to (v) quantify these geomorphological impacts.

2. The Aziza cave

2.1. General overview

9The Aziza Cave, also referred to as Kef Aziza or Tazougart Cave (Oued Naam municipality), is situated approximately 80 km northeast of the city of Errachidia (32.029741°N, 3.788085°W; fig. 1). It lies on the southern margin of the eastern High Atlas Mountains of Morocco, near the boundary with the Saharan hamadas. The cave entrance, at an altitude of 1059 m, opens onto a rocky terrace approximately 30 m above the Guir River (fig. 2). The cave extends along a SE-NW axis and is predominantly subhorizontal, although it contains four sumps (Benani et al., 2022). Beyond these sumps, many passages remain flooded, whereas the downstream sections of the cave are dry. The total surveyed length exceeds 4 km (Benani et al., 2022), with the deepest point recorded in 2019 at -90 m (altitude 969 m). The downstream segment of the cave, located near the entrance and measuring 1540 m in length, has a long history of human visitation, as evidenced by numerous graffiti on its walls. These include inscriptions left by soldiers around 1920-1926 (unpublished), as well as the account of a visit by Beloin in 1925 (Beloin, 1928).

Fig. 1 – Location of Aziza Cave. A: location of the cave and the province of Errachidia on a map of Morocco; B: location of the cave on a map of the province of Errachidia; C: location of the cave entrance on a map with the municipality of Oued Naan; D: location of the cave entrance at the Guir River south of Tazouguert.
Fig. 1 – Localisation de la grotte Aziza. A : localisation à l'échelle du Maroc de la grotte et de la province d'Errachidia ; B : localisation de la grotte à l'échelle de la Province d'Errachidia ; C : localisation de la grotte à l'échelle de la commune d'Oued Naan ; D : localisation de l'entrée de la grotte au niveau de l'oued Guir au sud de Tazouguert.

Fig. 1 – Location of Aziza Cave. A: location of the cave and the province of Errachidia on a map of Morocco; B: location of the cave on a map of the province of Errachidia; C: location of the cave entrance on a map with the municipality of Oued Naan; D: location of the cave entrance at the Guir River south of Tazouguert.Fig. 1 – Localisation de la grotte Aziza. A : localisation à l'échelle du Maroc de la grotte et de la province d'Errachidia ; B : localisation de la grotte à l'échelle de la Province d'Errachidia ; C : localisation de la grotte à l'échelle de la commune d'Oued Naan ; D : localisation de l'entrée de la grotte au niveau de l'oued Guir au sud de Tazouguert.

Fig. 2 – The entrance to Aziza Cave is located on the right bank of the Guir River and at the base of the Tazougart Plateau (photo by J.Ph. Dégletagne).
Fig. 2 – L’entrée de la grotte Aziza se trouve sur la rive droite de l’oued Guir et à la base du plateau de Tazougart (photo J.Ph. Dégletagne).

Fig. 2 – The entrance to Aziza Cave is located on the right bank of the Guir River and at the base of the Tazougart Plateau (photo by J.Ph. Dégletagne).Fig. 2 – L’entrée de la grotte Aziza se trouve sur la rive droite de l’oued Guir et à la base du plateau de Tazougart (photo J.Ph. Dégletagne).

10The cave is situated within the Saharan bioclimatic zone. Summer temperatures are high, reaching nearly 50 °C, whereas winter nights can be cold, with temperatures dropping to -8 °C. Annual precipitation is approximately 120 mm. Within the cave, the temperature stabilizes at approximately 22 °C at a distance of 450 m from the entrance (Aulagnier and Destre, 1985). Beyond this point, the air becomes saturated with moisture, and condensation becomes noticeable from 650 m from the entrance.

11The Tazougart Plateau, or Jbel Chaaba, is a southward-sloping landform, rising to an altitude of 1266 m, and cut by the Guir River, which descends from the High Atlas towards the south through gorges at an elevation of approximately 1000 m. The plateau is composed of Upper Cenomanian–Turonian limestones (Akarbous Formation; Andreu et al., 2013), which overlie marls and sandstones and dip southward (Fig. 1, 3). The plateau is bounded to the northwest by a limestone escarpment, to the east by the Guir Gorge, and slopes southwards toward the South Atlas trough. The Aziza Cave is primarily situated at the base of the limestone formation. It represents an ancient conduit that once drained the Jbel Chaaba Plateau and is now abandoned, perched above the wadi.

Fig. 3 – Geological and topographical context of Jbel Chaaba. A: the plateau is built with limestone resting on Upper Cretaceous marl (after the 1:50,000 geological map of Morocco, “Tazougart”). The location of the cave is shown in red, and the location of the geological profile in (C) is shown in dotted lines; B: satellite view, showing the major structural features. The location of the cave is shown in red; C: geological cross-section along the axis of the cave.
Fig. 3 – Contexte géologique et topographique du Jbel Chaaba. A : le plateau est armé de calcaires reposant sur des marnes du Crétacé supérieur (d’après la carte géologique du Maroc au 1/50 000 « Tazougart »). Le report de la cavité est indiqué en rouge, l’emplacement de la coupe en (C) est indiqué en pointillé ; B : vue satellite, avec indication des grands traits structuraux. Le report de la cavité est indiqué en rouge ; C : coupe géologique le long de l’axe de la grotte.

Fig. 3 – Geological and topographical context of Jbel Chaaba. A: the plateau is built with limestone resting on Upper Cretaceous marl (after the 1:50,000 geological map of Morocco, “Tazougart”). The location of the cave is shown in red, and the location of the geological profile in (C) is shown in dotted lines; B: satellite view, showing the major structural features. The location of the cave is shown in red; C: geological cross-section along the axis of the cave.Fig. 3 – Contexte géologique et topographique du Jbel Chaaba. A : le plateau est armé de calcaires reposant sur des marnes du Crétacé supérieur (d’après la carte géologique du Maroc au 1/50 000 « Tazougart »). Le report de la cavité est indiqué en rouge, l’emplacement de la coupe en (C) est indiqué en pointillé ; B : vue satellite, avec indication des grands traits structuraux. Le report de la cavité est indiqué en rouge ; C : coupe géologique le long de l’axe de la grotte.

2.2. Initial hypotheses on the formation of the cave

12The first segment of the cave is notable for its considerable dimensions, with several sections displaying clear evidence of vadose activity. In the second segment, the cave narrows and branches multiple times while retaining a predominantly phreatic morphology. Evidence of vadose processes gradually increases in this section. Many of the branches in this area are currently flooded with water that shows no evident flow but does not stagnate; moreover, indications suggest a possible reversal in the direction of water movement (Benani et al., 2022). An initial interpretation of the origin of the bell holes or cupolas in the entrance zone was proposed by Bini (2007), suggesting that they may be related to thermal convection processes (Audra, 2017).

2.3. Historical data on fauna in Aziza Cave

13The presence of the Guir River and an oasis, which provide food resources for bats, together with the space offered by the cave and its climatic conditions, are likely reasons why bats use this cave. Aulagnier and Destre (1985) conducted ten visits to the cave between January 1982 and June 1984. During these surveys, bats were identified to species level, and their roosting sites were mapped. To achieve a comprehensive inventory of the species and population sizes within the cave, all relevant Moroccan literature was reviewed, focusing on studies pertaining to the Aziza Cave and its surrounding area (Dbiba et al., 2025). The Draa-Tafilalet region hosts 22 bat species, including seven species recorded within the Aziza Cave (Aulagnier and Destre, 1985).

14In addition to its chiropteran colonies, Aziza Cave harbors a rich and heterogeneous assemblage of invertebrates that reflects the ecological complexity of subterranean habitats. Early records (Canals and Viñas, 1969; Español, 1969; Auroux, 1986; Sánchez, 1970; Lagar, 1978; Ribera, 1983; Bolonić et al., 1983; Buzio et al., 2003; Barranco and Mayoral, 2007; Stüben, 2009) revealed a remarkable diversity of invertebrates representing multiple taxonomic groups. The collected specimens include both terrestrial and aquatic forms, highlighting the ecological heterogeneity of the cave system.

3. Methods

3.1. Climatology

15To obtain data on the aerology of the cavity, CO2 concentrations were measured using an Industrial Scientific MX6 Hybrid analyzer, air velocity was measured with a Testo 888 anemometer, temperature was recorded with a VWR Traceable laser thermometer, and relative humidity was measured using an Omega RH85 hygrometer. The measurements were taken on 28 April 2017 and 8-9 October 2022.

3.2. Topographic and morphological surveys

16Two approaches were employed for the topographic surveys. The first utilized a Disto-X device, with the resulting 3D projections of the cave using Visual Topo software. Additionally, 3D laser scanning was performed with a FARO FOCUS 70 TLS to capture the main entrance, principal axes, and large chambers, with the final rendering generated using Scene software. Morphological surveys were conducted through photogrammetry. Four sections of the cave (fig. 4, PhG1 to PhG4), spanning from the entrance to the inner portion of the Guano Chamber, were captured using a LiDAR module coupled with a digital camera, operated either by hand or mounted on a telescopic pole. The resulting data were transferred to the Eléana workstation (Intel Core i9, 64 GB RAM, 2 TB SSD, 8 GB CUDA graphics card) and processed with Zephyr ©3DFlow to produce the final digital twin (textured 3D model). The topographic and lidar surveys were carried out by members of the Moroccan Explorers association (Benani et al., 2022) during march 2019. The photogrammetric surveys carried out by J.P. Dégletagne were conducted on 8 and 9 October 2022.

Fig. 4 – Location of the cave sections surveyed using photogrammetry and the corresponding described segments. Coordinate Systems: WGS 1984 UTM zone 30N, projection: transverse Mercator, Datum: WGS 1984, Moroccan Explorers Association, March 2019, 3335 m long, -87 m depth.
Fig. 4 - Position des différentes parties de la grotte ayant fait l’objet d’un relevé photogrammétrique et des différentes sections décrites. Systèmes de coordonnées : WGS 1984 zone UTM 30N, projection : Mercator transversale, datum : WGS 1984, Association marocaine des explorateurs, mars 2019, 3335 m de long, -87 m de profondeur.

Fig. 4 – Location of the cave sections surveyed using photogrammetry and the corresponding described segments. Coordinate Systems: WGS 1984 UTM zone 30N, projection: transverse Mercator, Datum: WGS 1984, Moroccan Explorers Association, March 2019, 3335 m long, -87 m depth.Fig. 4 - Position des différentes parties de la grotte ayant fait l’objet d’un relevé photogrammétrique et des différentes sections décrites. Systèmes de coordonnées : WGS 1984 zone UTM 30N, projection : Mercator transversale, datum : WGS 1984, Association marocaine des explorateurs, mars 2019, 3335 m de long, -87 m de profondeur.

1. Cave entrance; 2. Cave development; 3. Cave development buffer.
1. Entrée de la grotte ; 2. Développement de la grotte ; 3. Zone tampon du développement de la grotte.

3.3. Mineralogical analyses

17To determine the mineralogical composition of the sediments and crusts found on the cave floor and walls, X-ray diffraction (XRD) analyses were conducted in several laboratories on approximately 40 sediment samples collected from floor deposits and wall crusts (fig. 5). At CINaM (Aix-Marseille University), measurements were conducted using a Rigaku RU-200BH X-ray generator equipped with a rotating anode, Osmic multilayer optics, and a MAR345 2D detector. Cu Kα radiation (λ = 0.15418 nm) was employed. Samples were finely ground, thoroughly homogenized, and then loaded into 0.5 mm diameter glass capillaries. The volume of powder exposed to X-rays was approximately 0.1 μL. Diffractograms were analyzed using X'Pert HighScore software. At Abdelmalek Essaadi University (Tetouan), finely ground powders were scanned in a θ-2θ (Bragg–Brentano) geometry to record diffracted intensity according to Bragg's law and determine phase composition and crystalline parameters. Measurements were performed on a Bruker D8 Advance ECO equipped with a Cu Kα X-ray tube (λ ≈ 1.5406 Å, 25 mA, 40 kV) and a LYNXEYE XE-T energy-dispersive strip detector. Samples were loaded in powder holders or quartz/glass capillaries (0.3-1 mm diameter), with a powder volume sufficient to absorb the beam without excess. Optics (slits, mirrors, filters), angular range, and step size (5°-64°) were adjusted prior to acquisition and processing of the diffraction patterns. Additionally, samples numbered Aziza 1 to 6 were analyzed by XRD at CEREGE (Aix Marseille University) following the method described in Audra et al. (2016).

Fig. 5 – Aziza Cave: location of samples collected for mineralogical analysis. Coordinate Systems: WGS 1984 UTM zone 30N, projection: transverse Mercator, Datum: WGS 1984, Moroccan Explorers Association, March 2019, 3335 m long, -87 m depth.
Fig. 5 – Grotte Aziza : position des échantillons prélevés pour analyses minéralogiques. Systèmes de coordonnées : WGS 1984 zone UTM 30N, projection : Mercator transversale, datum : WGS 1984, Association marocaine des explorateurs, mars 2019, 3335 m de long, -87 m de profondeur.

Fig. 5 – Aziza Cave: location of samples collected for mineralogical analysis. Coordinate Systems: WGS 1984 UTM zone 30N, projection: transverse Mercator, Datum: WGS 1984, Moroccan Explorers Association, March 2019, 3335 m long, -87 m depth.Fig. 5 – Grotte Aziza : position des échantillons prélevés pour analyses minéralogiques. Systèmes de coordonnées : WGS 1984 zone UTM 30N, projection : Mercator transversale, datum : WGS 1984, Association marocaine des explorateurs, mars 2019, 3335 m de long, -87 m de profondeur.

1. Cave entrance; 2. Cave development; 3. Cave development buffer.
1. Entrée de la grotte ; 2. Développement de la grotte ; 3. Zone tampon du développement de la grotte.

3.4. Isotopic analyses

18Isotopic analyses of δ¹⁸O and δ¹³C were performed on a calcite sample collected from a series of rimstones located approximately 400 m from the entrance to determine the temperature of the water responsible for these formations (fig. 4, 12). An attempt was also made to date this sample using the U/Th method; however, this was unsuccessful due to significant detrital contamination.

19Stable isotopes of oxygen and carbon (δ¹⁸O and δ¹³C, standardized relative to Vienna Pee Dee Belemnite, VPDB) in calcite were measured at the University of Cambridge, UK, with an analytical precision better than 0.1 ‰ (for details, see Gázquez et al., 2018a). Calcite sampling targeted carbonate deposits that could potentially record signals of past hydrothermal activity. δ¹⁸O is employed here to estimate the temperature of calcite at the time of precipitation (e.g., Gázquez et al., 2018b; Columbu et al., 2020), based on the temperature-dependent fractionation factor (αcalcite–water) between the mineral and the aqueous solution (Tremaine et al., 2011). This relationship is expressed by the following equation:

20where T is the temperature (degrees Kelvin), and αcalcite-water is:

21In summary, δ¹⁸Ocalcite depends on both the water temperature and δ¹⁸Owater at the time of mineral precipitation. Paleo-water temperatures were estimated using: (i) δ¹⁸Ocalcite values obtained from calcite samples collected in the cave, and (ii) a δ¹⁸Owater value of -3.3 ‰ (V-SMOW), corresponding to the present-day local average δ¹⁸O of precipitation. It should be noted, however, that this value – and the resulting temperature estimates – remain approximate, as the δ¹⁸O of paleo-water is unknown and may have varied over time in response to climatic fluctuations.

3.5. New acquisitions of bat data

22In order to complete the data on bats, in 2022, two consecutive daytime surveys were conducted on 8 and 9 October with new methods. The cave was explored from the entrance to the first sump. An approach combining acoustic detection and direct observation, following the methodology of Dbiba et al. (2023), was employed. The location of each species within the cave was recorded to determine their spatial distribution. Collected echolocation calls were analyzed using Kaleidoscope software version 5.4.8 with the following settings: window size 128, FFT size 512, and maximum cache size 256. Calls were identified using the sound library of Barataud (2020) and unpublished reference calls collected from various locations in Morocco (Dbiba, personal data).

23The Aziza Cave hosts the recently described species Miniopterus maghrebensis, which occurs in sympatry with Miniopterus schreibersii (Puechmaille et al., 2014). Due to difficulties in distinguishing them morphologically and acoustically, the two species are here treated collectively as the Miniopterus schreibersii/maghrebensis complex.

3.6. New data on invertebrates

24Since 2018, new research has been conducted by the Marrakech Natural History Museum, in collaboration with several national and international institutions, to expand the cave’s faunal inventory. Samples were collected from the cave, and bait traps were deployed to attract invertebrates. The specimens were subsequently identified in the laboratory.

4. Results

4.1. Climatology

25During our surveys in November 2017 and October 2022, we recorded slightly different environmental conditions (tab. 1).

Tab. 1 – Climatic parameters recorded in Aziza Cave during November 2017 and October 2022.
Tab. 1 – Paramètres climatologiques relevés dans la grotte Aziza en novembre 2017 et octobre 2022.

Tab. 1 – Climatic parameters recorded in Aziza Cave during November 2017 and October 2022.Tab. 1 – Paramètres climatologiques relevés dans la grotte Aziza en novembre 2017 et octobre 2022.

26In December 2017, along the cave from the entrance to the Guano Chamber, temperature gradually increased from 14.0 to 21.0 °C, while relative humidity rose from 25.0 % to saturation. Up to the Guano Chamber, the cave is thus directly influenced by external climatic conditions, whereas beyond this point, the internal cave climate appears more stable.

4.2. Morphologies

27The cave comprises distinct sections according to distance from the entrance (fig. 4). Photogrammetric surveys are accessible on Sketchfab (https://sketchfab.com/​jpdeglet69/​collections/​kef-aziza-2978e8e4bfd466f8b3a14a664de40a4).

28The Aziza Cave exhibits a complex internal morphology that varies considerably with distance from the entrance. Here we will introduce a distinction between bell holes, which correspond to vertical cylinders, and cupolas, which correspond to rounded hemispheres. The cave entrance is marked by several large bell holes (PhG1, fig. 6A), heavily altered by past human activity, including explosive blasting, and is therefore excluded from analysis. Beyond this zone, the gallery initially follows gentle curves and cupolas before transitioning into a straight, tall segment (PhG2, S2, fig. 6B), with weathered lower walls and smooth upper walls (fig. 6C, 6D). The gallery then gradually widens while decreasing in height (PhG3, S3, fig. 6E, 6F), where ancient rimstones up to 2 m high are preserved in eroded form (fig. 6G). The ceiling in this section is punctuated by a series of cupolas. Further along, the gallery expands again, becoming both wide and high (S4, fig. 6H), with smooth, gently curving walls, leading into the Guano Chamber (S5, fig. 6I), the largest of the cave. Its ceiling comprises large cupolas with nested secondary bell holes, and the wall bases are covered by sand mounds coated with phosphate minerals. A flat limestone surface about 10 cm wide atop these mounds indicates wall retreat and areas protected from guano-derived aerosols (fig. 6J). Beyond the Guano Chamber, the cave continues as a broad, high gallery with numerous interlocking bell holes (PhG4, S6, fig 7A-E), which gradually narrows as the ceiling height decreases, forming a succession of ogive-shaped bell holes and culminating in a fork (S7-S8, fig. 7F). Lower walls in this area display calcite deposits of presumed underwater origin. Branches from this fork become progressively narrower and lower (S9, S11), retaining a phreatic morphology with emerging vadose characteristics; two dry sumps are present, with sump 1 distinguished by guano and clay deposits (fig. 7G, 7H). The second portion of the main branch is relatively low, averaging 2 m in height and 1.6 m in width (S11-S12, fig. 7J), with phreatic morphology and signs of vadose evolution. Some branches have elliptical to subcircular cross-sections, and the last 800 m retain these traits without bell holes, containing water that shows no apparent flow yet is not stagnant, with incision marks suggesting a probable reversal of flow direction. This section terminates at sump 4, beyond which exploration continued by Moroccan speleologists without topographical surveys. The galleries progressively narrow, requiring crawling or crouching, and finally end at sump 5, which remains untraversed.

Fig. 6 – Aziza Cave, views of the different sections of galleries from the entrance to the Guano Chamber. A: the entrance area of the Aziza Cave, particularly on the east side (PhG1), displays several large bell holes, the formation of which has been significantly affected by past use of explosives. While the northern section of the entrance exhibits fewer bell holes, those present are considerable in volume, as revealed by photogrammetric surveys; B: immediately after entering the cave, the gallery walls are smooth (photo. H. Benani); C: narrow, high gallery. The base of the walls is weathered, while the upper part is smooth (PhG2, S2); D: narrow, tall gallery. The ceiling features a few subtly pronounced cupolas (PhG2, S2); E: the gallery widens while its height decreases. Numerous cupolas are present, though they are not very pronounced (PhG3, S3); F: gallery nearly as wide as it is high. The base is directly altered by guano, while the upper part is affected by aerosols (PhG3, S3); G: ancient rimstones, sampled for stable isotopes and U/Th dating (photo. M. Renda); H: high and wide gallery. The walls are smooth and their northern base is covered with sediments (photo. M. Renda, S4); J: the Guano Chamber, the largest in the cave, with large cupolas and nested bell holes (photo. M. Renda, S5); K: north wall of the Guano Chamber and top of the mound at the base of the walls. The wall has receded by about 10 cm from its original position prior to exposure to aerosols linked to bat droppings (photo. L. Barriquand). Figure 5 shows the location of photogrammetries (J.Ph. Deglétagne).
Fig. 6 – Grotte Aziza, vues des différentes sections de galeries de l'entrée à la salle du Guano. A : zone d’entrée, côté est, le vide au-dessus des personnages est lié à l’utilisation d’explosifs. Au nord, les coupoles sont peu nombreuses mais de grand volume (PhG1) ; B : immédiatement après l’entrée de la grotte. Les parois sont lisses (S1) (photo. H. Benani) ; C : galerie étroite et haute. La base des parois est altérée, la partie haute est lisse (PhG2, S2) ; D : galerie étroite et haute. La voûte présente quelques coupoles peu marquées (PhG2, S2) ; E : la largeur de la galerie augmente, sa hauteur diminue. Les coupoles sont nombreuses mais peu marquées (PhG3, S3) ; F : galerie pratiquement aussi large que haute. La base est altérée directement par les guanos alors que la partie haute est altérée par les aérosols (PhG3, S3) ; G : les anciens gours, échantillonnés pour les isotopes stables et la datation U/Th (photo. M. Renda) ; H : galerie haute et large. Les parois sont lisses et leur base nord est recouverte de sédiments (photo. M. Renda, S4) ; J : la salle du Guano, la plus vaste de la grotte, avec de grandes coupoles et des bell holes emboîtés (photo. M. Renda, S5) ; K : paroi nord de la salle du Guano et sommet du monticule se trouvant à la base des parois. La paroi a subi un recul d’une dizaine de centimètre par rapport à son état avant exposition aux aérosols liés aux déjections des chauves-souris. La Figure 5 indique la localisation des photogrammétries (J.Ph. Deglétagne).

Fig. 6 – Aziza Cave, views of the different sections of galleries from the entrance to the Guano Chamber. A: the entrance area of the Aziza Cave, particularly on the east side (PhG1), displays several large bell holes, the formation of which has been significantly affected by past use of explosives. While the northern section of the entrance exhibits fewer bell holes, those present are considerable in volume, as revealed by photogrammetric surveys; B: immediately after entering the cave, the gallery walls are smooth (photo. H. Benani); C: narrow, high gallery. The base of the walls is weathered, while the upper part is smooth (PhG2, S2); D: narrow, tall gallery. The ceiling features a few subtly pronounced cupolas (PhG2, S2); E: the gallery widens while its height decreases. Numerous cupolas are present, though they are not very pronounced (PhG3, S3); F: gallery nearly as wide as it is high. The base is directly altered by guano, while the upper part is affected by aerosols (PhG3, S3); G: ancient rimstones, sampled for stable isotopes and U/Th dating (photo. M. Renda); H: high and wide gallery. The walls are smooth and their northern base is covered with sediments (photo. M. Renda, S4); J: the Guano Chamber, the largest in the cave, with large cupolas and nested bell holes (photo. M. Renda, S5); K: north wall of the Guano Chamber and top of the mound at the base of the walls. The wall has receded by about 10 cm from its original position prior to exposure to aerosols linked to bat droppings (photo. L. Barriquand). Figure 5 shows the location of photogrammetries (J.Ph. Deglétagne).Fig. 6 – Grotte Aziza, vues des différentes sections de galeries de l'entrée à la salle du Guano. A : zone d’entrée, côté est, le vide au-dessus des personnages est lié à l’utilisation d’explosifs. Au nord, les coupoles sont peu nombreuses mais de grand volume (PhG1) ; B : immédiatement après l’entrée de la grotte. Les parois sont lisses (S1) (photo. H. Benani) ; C : galerie étroite et haute. La base des parois est altérée, la partie haute est lisse (PhG2, S2) ; D : galerie étroite et haute. La voûte présente quelques coupoles peu marquées (PhG2, S2) ; E : la largeur de la galerie augmente, sa hauteur diminue. Les coupoles sont nombreuses mais peu marquées (PhG3, S3) ; F : galerie pratiquement aussi large que haute. La base est altérée directement par les guanos alors que la partie haute est altérée par les aérosols (PhG3, S3) ; G : les anciens gours, échantillonnés pour les isotopes stables et la datation U/Th (photo. M. Renda) ; H : galerie haute et large. Les parois sont lisses et leur base nord est recouverte de sédiments (photo. M. Renda, S4) ; J : la salle du Guano, la plus vaste de la grotte, avec de grandes coupoles et des bell holes emboîtés (photo. M. Renda, S5) ; K : paroi nord de la salle du Guano et sommet du monticule se trouvant à la base des parois. La paroi a subi un recul d’une dizaine de centimètre par rapport à son état avant exposition aux aérosols liés aux déjections des chauves-souris. La Figure 5 indique la localisation des photogrammétries (J.Ph. Deglétagne).

Fig. 7 – Aziza Cave, views of the different sections of galleries beyond the Guano Chamber. A and B: beyond from the Guano Chamber, a wide and high gallery. The walls are smooth and the ceiling is marked by numerous bell holes (photo. M. Renda; PhG4, S6); C: beyond the Guano Chamber, there are numerous, very distinct bell holes (PhG4, S6); D: nested bell holes beyond of the Guano Chamber; E: ceiling made up of nested bell holes beyond the Guano Chamber; F: the gallery narrows again. The ceiling is marked by ogive-shaped bell holes, and the walls are smooth (photo. H. Benani); G: bell holes just before sump 1, with a rim of apatite crust; the largest is 1.8 m long, with three small bell holes 1.5 m high (photo. H. Benani); H: section of the gallery at sump 1. The gallery is narrow with a low ceiling. The walls are jagged, with virtually no biocorrosion (photo. H. Benani); J: gallery downstream of siphon 2, the walls are jagged (photo. H. Benani). Figure 5 shows the location of photogrammetries (J.Ph. Deglétagne).
Fig. 7 – Grotte Aziza, vues des différentes sections de galeries au-delà de la salle du Guano. A et B : en amont de la salle du Guano, galerie large et haute. Les parois sont lisses et le plafond est marqué par de nombreuses coupoles (photo M. Renda ; PhG4, S6) ; C : au-delà de la salle du Guano, les coupoles sont très nombreuses et très marquées ; D : coupoles emboîtées en amont de la salle du Guano ; E : plafond constitué par des coupoles emboîtées au-delà de la salle du Guano ; F : la galerie redevient étroite. Le plafond est marqué par des coupoles en forme d’ogives, les parois sont lisses (photo H. Benani) ; G : coupoles juste avant le siphon 1, avec un liseré brun d’apatite ; la plus grande fait 1,8 m de longueur, pour 3 petites coupoles à 1,5 m de hauteur (photo. H. Benani) ; H : section de la galerie au siphon 1, la galerie est étroite, de faible hauteur. Les parois sont déchiquetées, la biocorrosion est quasiment absente (photo H. Benani) ; J : galerie en aval du siphon 2, les parois sont déchiquetées (photo H. Benani). La Figure 5 indique la localisation des photogrammétries (J.-Ph. Deglétagne).

Fig. 7 – Aziza Cave, views of the different sections of galleries beyond the Guano Chamber. A and B: beyond from the Guano Chamber, a wide and high gallery. The walls are smooth and the ceiling is marked by numerous bell holes (photo. M. Renda; PhG4, S6); C: beyond the Guano Chamber, there are numerous, very distinct bell holes (PhG4, S6); D: nested bell holes beyond of the Guano Chamber; E: ceiling made up of nested bell holes beyond the Guano Chamber; F: the gallery narrows again. The ceiling is marked by ogive-shaped bell holes, and the walls are smooth (photo. H. Benani); G: bell holes just before sump 1, with a rim of apatite crust; the largest is 1.8 m long, with three small bell holes 1.5 m high (photo. H. Benani); H: section of the gallery at sump 1. The gallery is narrow with a low ceiling. The walls are jagged, with virtually no biocorrosion (photo. H. Benani); J: gallery downstream of siphon 2, the walls are jagged (photo. H. Benani). Figure 5 shows the location of photogrammetries (J.Ph. Deglétagne).Fig. 7 – Grotte Aziza, vues des différentes sections de galeries au-delà de la salle du Guano. A et B : en amont de la salle du Guano, galerie large et haute. Les parois sont lisses et le plafond est marqué par de nombreuses coupoles (photo M. Renda ; PhG4, S6) ; C : au-delà de la salle du Guano, les coupoles sont très nombreuses et très marquées ; D : coupoles emboîtées en amont de la salle du Guano ; E : plafond constitué par des coupoles emboîtées au-delà de la salle du Guano ; F : la galerie redevient étroite. Le plafond est marqué par des coupoles en forme d’ogives, les parois sont lisses (photo H. Benani) ; G : coupoles juste avant le siphon 1, avec un liseré brun d’apatite ; la plus grande fait 1,8 m de longueur, pour 3 petites coupoles à 1,5 m de hauteur (photo. H. Benani) ; H : section de la galerie au siphon 1, la galerie est étroite, de faible hauteur. Les parois sont déchiquetées, la biocorrosion est quasiment absente (photo H. Benani) ; J : galerie en aval du siphon 2, les parois sont déchiquetées (photo H. Benani). La Figure 5 indique la localisation des photogrammétries (J.-Ph. Deglétagne).

29These morphological variations can be summarized using the 3D models of the cavity that have been produced (fig. 8).

Fig. 8 – 3D model of most of the network before sumps 1 and 2, produced using Visual Topo (Benani et al., 2022).
Fig. 8 – Modèle 3D de la partie de la majeure partie du réseau avant les siphons 1 et 2, obtenu avec Visual Topo (Benani et al., 2022).

Fig. 8 – 3D model of most of the network before sumps 1 and 2, produced using Visual Topo (Benani et al., 2022).Fig. 8 – Modèle 3D de la partie de la majeure partie du réseau avant les siphons 1 et 2, obtenu avec Visual Topo (Benani et al., 2022).

30As for the bell holes, they are mostly nested within each other (fig. 9), making it difficult to measure their dimensions. In the PhG2 area, their heights generally range from 30 to 40 cm. In the PhG3 area, most bell holes measure between 25 and 35 cm, with only a few reaching 60 to 70 cm. In the PhG4 area, nearly all the bell holes are nested within one another, with average heights ranging from 80 to 130 cm.

Fig. 9 – 3D textured view of nested bell holes beyond the Guano Chamber (J.Ph. Dégletagne).
Fig. 9 – Vue 3D texturée de coupoles emboîtées au-delà de la salle du Guano (J.Ph. Dégletagne).

Fig. 9 – 3D textured view of nested bell holes beyond the Guano Chamber (J.Ph. Dégletagne).Fig. 9 – Vue 3D texturée de coupoles emboîtées au-delà de la salle du Guano (J.Ph. Dégletagne).

4.3. Invertebrates

31The identified assemblage encompasses several major classes: Arachnida (8 species), Insecta (6), Crustacea (4), Collembola (4), Chilopoda (2), Gastropoda (2), and Diplopoda (1). The species identified, along with their family affiliations and ecological status, are summarized below:

  • Arachnida: the cave hosts several arachnid species including Acari (Parasitengona sp. 1), Araneae such as Hahniidae (troglobitic), Dysdera sp. (troglobitic), Oecobius chassieri Lecigne and Moutaouakil, 2024 (troglobitic), and the troglobitic species Dysdera caeca Ribera, 1993. Additional arachnids include Linyphiidae, represented by Lepthyphantes fadriquei Barrientos, 2020, Palpigradi (Eukoenenia maroccana Barranco and Mayoral, 2007), and Pseudoscorpiones (Chthoniidae sp.);

  • Collembola: 4 collembolan taxa were observed, including Symphypleona (Arrhopalites sp.) and several Entomobryomorpha morphotypes (Entomobryidae sp. 1 and 2, Isotomidae sp. 1);

  • Insecta: the Coleoptera of Aziza Cave include Platyderus insignitus presaharensis Lagar Mascaró, 1978 (Carabidae, troglobitic), Torneuma troglodytis Stüben, 2009 (Curculionidae, troglobitic), Tychobythinus sp. (Pselaphinae), Apteranillus ruei Español, 1969 (Staphylinidae, troglobitic), and Scaurus tingitanus gimeli Peyerimhoff, 1948 (Tenebrionidae, troglobitic). A single Sternorrhyncha species (Kinnaridae sp.) was also recorded (troglobitic);

  • Diplopoda and Chilopoda: Diplopoda are represented by Jeekelosoma abadi Mauriès, 1985 (Paradoxosomatidae, troglobitic), while Chilopoda include Cryptops aff. numidicus aelleni Manfredi, 1956 (Cryptopidae);

  • Geophilomorpha and other soil-dwelling taxa: a single geophilomorph morphotype was recorded;

  • Crustacea: aquatic taxa comprise Bathynellacea (Bathynellaceae sp., stygobitic), Isopoda such as Castellanetes sp. (Ollibrinidae, troglobitic), Magnezia gardei Magniez, 1977 (Stenasellidae, stygobitic), and unidentified Copepoda sp. (stygobitic);

  • Gastropoda: Gastropod species were represented by a Hydrobiidae sp. (stygobitic) and an Eupulmonata morphotype.

32The terrestrial fauna is mainly concentrated in areas rich in organic matter and high humidity, such as guano chambers and deep clay deposits. Species such as Scaurus tingitanus gimeli and Platyderus insignitus presaharensis were recorded between 200 and 800 m from the entrance, while the Palpigrade Eukoenenia maroccana and the spider Lepthyphantes fadriquei were observed beyond the Guano chamber. In contrast, aquatic forms – including the isopod Magniezia gardei, a hydrobiid gastropod, a copepod species, and a Bathynellacea species – were found in small pools and permanent lakes located in the deeper sections of the cave.

4.4. Mineralogy

33Twenty-seven mineral species were identified, including about a dozen silicates, phyllosilicates, and oxyhydroxides, three sulfates, one carbonate, and ten phosphates (tab. 2).

Tab. 2 – Minerals identified by XRD.
Tab. 2 – Minéraux identifiés par DRX.

Tab. 2 – Minerals identified by XRD.Tab. 2 – Minéraux identifiés par DRX.

xxx = abundant; xx = present; x = traces; ? = possible occurrence.
xxx = abondant ; xx = présent ; x = traces ; ? = occurrence possible.

4.5. Stable isotopes of calcite

34The stable isotope values obtained from the calcite speleothems (rimstones) are δ¹⁸O = -11.10 ‰ and δ¹³C = -7.27 ‰. According to the equation presented above, the estimated calcite crystallization temperature is 35 °C.

4.6. Presence of bats

35The first surveys were conducted by Aulagnier and Destre (1985; fig. 10).

Fig. 10 – Presence and seasonality of the bat species identified in Aziza Cave, according to Aulagnier and Destre (1985). 1: Rhinolophus blasii, winter; 2: Rhinopoma cystops, winter and spring; 3: Miniopterus maghrebensis, spring; 4: Rhinolophus blasii, spring; 5: Aselia tridents, summer; 6: Plecotus gaisieri, summer; 7: Rhinolophus ferrumequinum and Myoris blytii, summer. Coordinate Systems: WGS 1984 UTM zone 30N, projection: transverse Mercator, Datum: WGS 1984, Moroccan Explorers Association, March 2019, 3335 m long, -87 m depth.
Fig. 10 – Présence et saisonnalité des différentes espèces de chiroptères déterminés dans la grotte Aziza, d’après Aulagnier et Destre (1985).

1 : Rhinolophus blasii, hiver ; 2 : Rhinopoma cystops, hiver et printemps ; 3 : Miniopterus maghrebensis, printemps ; 4 : Rhinolophus blasii, printemps ; 5 : Aselia tridents, été ; 6 : Plecotus gaisieri, été ; 7 : Rhinolophus ferrumequinum et Myoris blytii, été. Systèmes de coordonnées. WGS 1984 zone UTM 30N, projection : Mercator transversale, datum : WGS 1984, Association marocaine des explorateurs, mars 2019, 3335 m de long, -87 m de profondeur.

1 : Rhinolophus blasii, hiver ; 2 : Rhinopoma cystops, hiver et printemps ; 3 : Miniopterus maghrebensis, printemps ; 4 : Rhinolophus blasii, printemps ; 5 : Aselia tridents, été ; 6 : Plecotus gaisieri, été ; 7 : Rhinolophus ferrumequinum et Myoris blytii, été. Systèmes de coordonnées. WGS 1984 zone UTM 30N, projection : Mercator transversale, datum : WGS 1984, Association marocaine des explorateurs, mars 2019, 3335 m de long, -87 m de profondeur.

1. Cave entrance; 2. Cave development; 3. Cave development buffer.
1. Entrée de la grotte ; 2. Développement de la grotte ; 3. Zone tampon du développement de la grotte.

36Following two consecutive daytime visits in 2022, using a combination of acoustic and visual methods, a total of nine bat species were identified in the cave (tab. 3). Observed numbers varied by species, reflecting seasonal patterns. In terms of taxonomic diversity, the Vespertilionidae family, represented by three species, was the most diverse, followed by the Miniopteridae family with two species. The Rhinopomatidae and Rhinolophidae families were each represented by a single species. In terms of abundance, the Miniopterus schreibersii/maghrebensis complex was the most numerous, with approximately 1000 individuals, followed by Rhinopoma cystops (230 individuals) and Myotis punicus (200 individuals). The remaining species were recorded in low numbers, not exceeding ten individuals each.

Tab. 3 – Species richness and abundance of bats identified in Aziza cave in October. 2022.
Tab. 3 – Espèces de chiroptères et abondance dans la grotte d’Aziza en octobre 2022.

Tab. 3 – Species richness and abundance of bats identified in Aziza cave in October. 2022.Tab. 3 – Espèces de chiroptères et abondance dans la grotte d’Aziza en octobre 2022.

37In October 2022, bats were found to be distributed variably along the cave, from the entrance to the first sump (fig. 11). Rhinopoma cystops occupied the entrance area up to sector PhG2, forming a large colony in a bell hole, with a few isolated individuals observed deeper inside the cave. The schreibersii/maghrebensis complex, the most abundant species, was distributed from the first few meters of the cave to the first sump, with a large colony located in the Guano Chamber.

Fig. 11 – Locations and abundance of the different bat species in October 2022. 1: Miniopterus shreibersii/maghrebensis (1000); 2: Rhinopoma cystops (230); 3: Plecotus gaisieri; 4: Rhinolophus blasii (8); 5: Myotis punicus (200); 6: Rhinolophus ferrumequinum (1) and Myotis mystacinus (8). Coordinate Systems: WGS 1984 UTM zone 30N, projection: transverse Mercator, Datum: WGS 1984, Moroccan Explorers Association, March 2019, 3335 m long, -87 m depth.
Fig. 11 – Positions et effectifs des différentes espèces de chauves-souris en octobre 2022. 1 : Miniopterus shreibersii/maghrebensis (1000) ; 2 : Rhinopoma cystops (230) ; 3 : Plecotus gaisieri ; 4 : Rhinolophus blasii (8) ; 5 : Myotis punicus (200) ; 6 : Rhinolophus ferrumequinum (1) and Myotis mystacinus (8). Systèmes de coordonnées : WGS 1984 zone UTM 30N, projection : Mercator transversale, datum : WGS 1984, Association marocaine des explorateurs, mars 2019, 3335 m de long, -87 m de profondeur.

Fig. 11 – Locations and abundance of the different bat species in October 2022. 1: Miniopterus shreibersii/maghrebensis (1000); 2: Rhinopoma cystops (230); 3: Plecotus gaisieri; 4: Rhinolophus blasii (8); 5: Myotis punicus (200); 6: Rhinolophus ferrumequinum (1) and Myotis mystacinus (8). Coordinate Systems: WGS 1984 UTM zone 30N, projection: transverse Mercator, Datum: WGS 1984, Moroccan Explorers Association, March 2019, 3335 m long, -87 m depth.Fig. 11 – Positions et effectifs des différentes espèces de chauves-souris en octobre 2022. 1 : Miniopterus shreibersii/maghrebensis (1000) ; 2 : Rhinopoma cystops (230) ; 3 : Plecotus gaisieri ; 4 : Rhinolophus blasii (8) ; 5 : Myotis punicus (200) ; 6 : Rhinolophus ferrumequinum (1) and Myotis mystacinus (8). Systèmes de coordonnées : WGS 1984 zone UTM 30N, projection : Mercator transversale, datum : WGS 1984, Association marocaine des explorateurs, mars 2019, 3335 m de long, -87 m de profondeur.

1: Cave entrance; 2 Cave development; 3 Cave development buffer.
1. Entrée de la grotte ; 2. Développement de la grotte ; 3. Zone tampon du développement de la grotte.

38One Plecotus gaisleri was observed in the first section of the cave. Further downstream, eight Rhinolophus blasii were counted at approximately 370 m from the entrance. Myotis punicus occurs from the Guano Chamber to the first siphon, coexisting with a single Rhinolophus ferrumequinum and eight Myotis mystacinus.

5. Discussion

5.1. Interactions between bats and the cave environment

39The water temperature reconstruction using the calcite stable isotopes indicates that during the formation of rimstones in Aziza Cave, water may have been slightly hydrothermal in the past (~35 °C), higher than present cave temperature (~22 °C). This may be a result of the arid environments where minimal meteoric infiltration limits groundwater cooling and, consequently, reduces the dissipation of deep aquifer heat from the geothermal gradient. Currently, and for the same reason, the cave temperature is still about 2 °C above the average external temperature.

40This study represents a first step toward understanding the mechanisms and interactions between bat species and cave environments. Although the monitoring period in Aziza Cave was relatively short, 8 bat species were identified, out of the 10 known to use this cave seasonally. By comparison, Aulagnier and Destre (1985) reported 7 species between January 1982 and June 1984, based on 10 visits spread across the year. They highlighted the seasonal use of the cave depending on the species: Rhinopoma hardwickei is present in winter, while the Miniopterus complex visits seasonally. Other species, such as Plecotus gaisleri, Rhinolophus ferrumequinum, Myotis punicus, and Asselia tridens, use the cave for summering or parturition. Only Rhinolophus euryale was observed year-round. The authors also noted that the different species show marked spatial preferences within the cave, with population numbers varying according to the season. Subsequently, Buzio et al. (2003) reported the presence of Rhinolophus euryale and several thousand individuals of Myotis punicus occupying almost all galleries downstream of the sumps, particularly concentrated in the Guano Chamber in spring 2002. However, during an earlier visit in November 1983, Bolonic et al. (1983) observed only Plecotus gaisleri and Miniopterus schreibersii. Overall, the available data suggest that Aziza Cave is frequented by 7 bat species throughout the year, with occupancy varying according to seasonal biological cycles (hibernation, summering, birthing, reproduction). These species appear to select different sections of the cave, likely depending on local microclimatic conditions such as temperature, humidity, and tranquility.

41They are absent from the deepest parts of the inner section and from the galleries beyond the sumps.

42During winter, the cave entrance is occupied by Rhinolophus blasii and Rhinopoma cystops. The former hibernates, with individuals spaced apart. Although colonies can be large (several thousand individuals), their lethargy during this period limits biocorrosion (minimal excrement, lowered body temperature, and low CO2 emissions). The latter remains active in winter but greatly reduces its activity. Individuals do not form swarms, and populations rarely exceed a few hundred. Consequently, their presence must have little impact on the environment: minimal excrement and negligible thermal or aerological effects due to the isolation of each individual on the walls.

43In spring, Rhinopoma cystops continues to occupy the cave entrance. It resumes normal activity, but individuals remain isolated on the walls. Despite their presence, no guano accumulates in this section of the cave. As a result, biocorrosion is also minimal, and the walls are barely affected, which explains why this part of the cave remains so narrow.

44In summer, Plecotus gaisleri occupies the section between the entrance and the area preceding the Guano Chamber. This bat species is poorly known and occurs in low numbers. Individuals live in isolation, with only a few present at any given time, occupying crevices. Consequently, the droppings they produce are minimal, and their thermal impact remains negligible. Their presence thus has little to no effect on the cave. Consequently, the cupolas in this area cannot be explained by this species. Beyond this section of the cave, both the number and size of cupolas and bell holes increase. In spring, the Miniopterus complex occupies this part of the cave and is fully active. The largest known populations in the Maghreb can reach up to a thousand individuals. These bats gather in swarms ranging from a few dozen to several thousand. The increase in the number and size of cupolas and bell holes appears to correlate with their presence.

45During summer, Miniopterus maghrebensis co-occurs with Myotis punicus in the Guano Chamber. Both species prefer large spaces, which allow them to form extensive swarms. Myotis punicus can form dense swarms numbering several hundred to several thousand individuals. These bats are fully active during this period, and with body temperatures around 38-39 °C, their swarming likely induces aerological changes near the cave ceiling, resulting in condensation and corrosion on the walls. In the Guano Chamber, these processes have caused the wall to recede by at least 10 cm, and the large bell holes must be produced by their presence (Lundberg and McFarlane, 2012).

5.2. Guano-derived morphologies and associated minerals

46Rhinolophus blasii, Rhinolophus ferrumequinum, and Myotis blythi are present in summer in the gallery beyond of the Guano Chamber. This part of the cave exhibits the highest density of bell holes in the cave (fig. 6K, 7A-D), which are also the highest. These bat species gather in colonies of several hundred, sometimes up to a thousand individuals during parturition. The swarms formed are generally dense. Their presence may therefore explain the formation of bell holes that are more distinct from each other, as the area occupied by the swarms is smaller than that of the Guano Chamber.

47Finally, in the area where the ogive-shaped bell holes are located, only Rhinolophus blasii is present during spring and summer. It forms compact swarms of usually a few hundred individuals (generally no more than 500). This behavior may explain the formation of these bell holes, which are clearly individualized and ogive-shaped.

48The presence of fresh guano in the cave indicates that these processes are still active and that microbiological activity continues within the cave (Sakoui et al., 2022). However, at this stage of the study, it is not possible to determine when they began. Dating of a speleothem failed due to its weathering, likely linked to biocorrosion. Such a date could have provided post-quem information on these processes.

49The swarming of bats results in droppings accumulating on the ground and at the base of the walls, which also causes aerological changes leading to condensation and corrosion on the walls (Audra et al., 2016). Beneath the guano, chemical reactions alter the walls, substrate, speleothems, and sedimentary fillings (Barriquand et al., 2024). This accounts for the presence of 10 phosphate and 3 sulfate minerals. The most common are brushite and hydroxylapatite, which form from reactions between calcium in the host rock and acidic phosphate leachate from the guano (Audra et al., 2017, 2019). Crandallite, variscite, and taranakite result from interactions with the host rock and clay, which provide aluminum. When Fe³⁺ ions are present, strengite and vivianite form, the latter being a rare mineral found in only about half a dozen caves worldwide (Audra et al., 2019). When only Fe³⁺ ions are present in clay, leucophosphite forms, and when ammonium ions are added to Fe³⁺, spheniscidite forms. Fluoride ions from bones allow the formation of fluorapatite. Finally, kaolinite and iron oxyhydroxides (goethite–hematite) may result from the alteration of phyllosilicates by acidic guano (Audra et al., 2021).

50The crystallization of sulfates is mainly controlled by the aerological conditions within the cave. Hexahydrite and epsomite were observed only during the November visit, at a single location on the reliefs along the drainage channel at the wall of the Guano Chamber. Their formation occurred at the edge of the area where cold external air dries as it warms. These two minerals are particularly rare due to the extremely dry conditions that govern their crystallization, especially hexahydrite, which has been reported in only about ten caves worldwide (Audra, 2022). They represent progressive dehydration stages of magnesium sulfates (fig. 12).

51Finally, silicates mainly originate from detrital inputs, entering through the cave entrance and being dispersed by runoff in the main gallery, or transported from the lower sections of the cave by internal water flows.

Fig. 12 – Stability diagram of magnesium sulfates (epsomite–hexahydrite–kieserite series) as a function of temperature and relative humidity (based on Hill and Forti, 1997, modified). The Aziza Cave area is indicated in red at the location and time of sampling.
Fig. 12 – Diagramme de stabilité des sulfates de magnésium (série epsomite-hexahydrite-kieserite) en fonction de la température et de l’humidité relative (d’après Hill et Forti, 1997, modifié). Le domaine de la grotte Aziza est indiqué en rouge, à l’emplacement et au moment de l’échantillonnage.

Fig. 12 – Stability diagram of magnesium sulfates (epsomite–hexahydrite–kieserite series) as a function of temperature and relative humidity (based on Hill and Forti, 1997, modified). The Aziza Cave area is indicated in red at the location and time of sampling.Fig. 12 – Diagramme de stabilité des sulfates de magnésium (série epsomite-hexahydrite-kieserite) en fonction de la température et de l’humidité relative (d’après Hill et Forti, 1997, modifié). Le domaine de la grotte Aziza est indiqué en rouge, à l’emplacement et au moment de l’échantillonnage.

5.3. The ecological importance of Aziza Cave for subterranean biodiversity

52The invertebrate community of Aziza Cave exhibits a remarkable degree of endemism and specialization, reflecting long-term isolation and adaptation to subterranean conditions. The assemblage is dominated by cave-adapted species (troglobites and stygobites), underlining the ecological significance and unique biogeographical role of this cave as a refuge for hypogean fauna within the arid environments of North Africa. Notably, several species – including Dysdera caeca, Lepthyphantes fadriquei, Eukoenenia maroccana, Platyderus insignitus presaharensis, Torneuma troglodytis, Apteranillus ruei, Scaurus tingitanus gimeli, Jeekelosoma abadi, and Magnezia gardei – are confirmed troglobitic or stygobitic taxa apparently restricted to Aziza Cave, emphasizing its role as an important locus of subterranean biodiversity. Among the described taxa, several are strictly subterranean and endemic to Aziza Cave, such as Jeekelosoma abadi Mauriès, 1985 (Diplopoda: Paradoxosomatinae), Magniezia gardei Magniez, 1977 (Isopoda: Stenasellidae), Eukoenenia maroccana Barranco and Mayoral, 2007 (Palpigradi: Eukoeneniidae), Dysdera caeca Ribera, 1993, Lepthyphantes fadriquei Barrientos, 2020, and Oecobius chassieri Lecigne and Moutaouakil, 2024 (Araneae: Dysderidae, Linyphiidae, and Oecobiidae, respectively). In addition, Platyderus insignitus presaharensis Lagar, 1978, Torneuma troglodytis Stüben, 2009, Apteranillus ruei Español, 1969, and Scaurus tingitanus gimeli Peyerimhoff, 1948 represent distinct troglobitic Coleoptera lineages. The collected fauna includes representatives of several major arthropod groups, notably Arachnida (Araneae, Pseudoscorpiones, and Acari), Crustacea (Isopoda), Myriapoda (Chilopoda and Diplopoda), Collembola and Insecta (Diptera, and Coleoptera). These taxa occupy different ecological niches, ranging from guano-rich areas to more oligotrophic zones, indicating both vertical and horizontal structuring within the cave ecosystem. Preliminary observations suggest that several of these species display morphological and behavioral traits typical of cave adaptation – such as depigmentation, eye reduction, and elongation of appendages – indicating the coexistence of trogloxenes, troglophiles, and troglobitic forms (Culver and Pipan, 2019; Gibert and Deharveng, 2002). Similar assemblage patterns associated with bat guano deposits have been reported in tropical and temperate caves (Ferreira et al., 2000; Gnaspini and Trajano, 2000), where organic enrichment supports complex detritivore and predator guilds. Although the present study primarily focuses on geomorphological processes induced by bats, these biological findings highlight the ecological importance of Aziza Cave as a potential hotspot of subterranean biodiversity in the region.

53The ecological importance of Aziza Cave for bats and invertebrate communities justifies adequate conservation measures. In Morocco, the roosts of bat species are subjected to numerous threats, including roost modification, guano extraction, myths and false beliefs, as well as the use of caves as corrals and burial sites for dead animals (Dbiba et al., 2023, 2025). The Aziza Cave is among the richest in terms of deposited guano, providing a concrete evidence of a long-term history between bats and the cave. However, any attempt to extract this guano would directly result in the loss of this habitat for these bats. Furthermore, many bats are listed as Vulnerable or Threatened according to the International Union for Conservation of Nature Red list (IUCN, 2025), highlighting the need for urgent protection measures and sensibilization of local populations. Therefore, any activity such as guano extraction should be strictly prohibited in order to preserve the ecological integrity of the cave and ensure the survival of its bat and invertebrate populations.

6. Conclusion

54The geomorphological study of Aziza Cave, along with research on its bat populations, shows that the biocorrosion processes associated with bats are closely linked to the behavior of the different species. In winter, during hibernation, biocorrosion is minimal. However, a few shallow bell holes may form in areas occupied by species that gather in swarms.

55Biocorrosion is most intense during periods of activity and swarming. These gatherings lead to the formation of large, sometimes nested bell holes, as well as the accumulation of excrement, which promotes biocorrosion and retreat of the walls, substrate, and exposed sediments, producing 13 phosphates and sulfates minerals, some rare in cave environment (vivianite and hexahydrite). Although the hypothesis of a hypogenic origin for the Aziza karst cannot be completely ruled out, this study demonstrates that the bell holes in the Aziza Cave are clearly associated with biocorrosion processes.

56Larger colonies, outside of hibernation periods, and the most compact swarms therefore produce the most significant geomorphological changes in a cave, as observed in the Guano Chamber and the gallery beyond of it in the Aziza Cave. The morphology of cave walls, therefore, depends primarily on the behavior of the bat species present.

57The coexistence of guanophilic invertebrate communities and biogenic corrosion phenomena emphasizes the interconnectedness of biological and geochemical processes in subterranean environments (Poulson and White, 1969; Simon et al., 2003). Future taxonomic and ecological investigations will be essential to fully characterize this fauna and to assess its functional role in nutrient cycling and mineral transformation within the cave ecosystem.

lionel.barriquand@wanadoo.fr + 33 6 81 48 44 46 0000-0001-9669-9933

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Version française abrégée

La biocorrosion liée aux chauves-souris est à l’origine d’une spéléogénèse secondaire dans les grottes. Elle se traduit par des morphologies spécifiques (Audra et al., 2016) et peut générer d’importants volumes (Barriquand et al., 2021a) mais aussi être à l’origine de la disparition d’œuvres pariétales (Bruxelles et al., 2016, 2021). L'éthologie des chauves-souris et leurs déchets (urine, guano, exhalaisons respiratoires) sont à l’origine de réactions chimiques provoquant ces phénomènes (Audra et al., 2017, 2019, 2021 ; Barriquand et al., 2024). De nombreuses espèces de chiroptères, se regroupant en colonies de tailles variables, fréquentent assidûment les mêmes réseaux karstiques. À ce jour, l’impact des chauves-souris sur la géomorphologie des cavités a été approchée globalement, nous proposons ici, après (i) une présentation de la grotte Aziza, (ii) d’identifier les espèces de chauves-souris présentes et leur modalité d’occupation, de leur éthologie, et des espaces qu’elles occupent en son sein, (iii) de définir les caractéristiques morphologiques des différentes parties de la cavité et (iv) de tenter de mettre en relation espèce, éthologie et géomorphologie associée, pour (v) essayer de quantifier ces impacts géomorphologiques.

La grotte Aziza est située sur les front sud du Haut Atlas oriental marocain (fig. 1-3). Elle a un développement de plus de 4000 m (fig. 4) dont 1540 sont accessibles aux chauves-souris. Aulagnier et Destre (1985) ont effectué 10 visites dans la cavité entre 1982 et 1984 et ont recensé et localisé les chiroptères présents. Nous avons complété ces données par détection acoustique et observation directe comme décrit dans Dbiba et al. (2023). Neuf espèces de chauves-souris ont été identifiées dans la grotte. Les effectifs observés varient selon les espèces, reflétant une certaine saisonnalité. Sur le plan quantitatif, le complexe Miniopterus schreibersii/maghrebensis était le plus abondant, avec environ 1000 individus, suivi de Rhinopoma cystops (230 individus) et Myotis punicus (200 individus). Les autres espèces présentaient des effectifs faibles. Les relevés topographiques (fig. 8) et morphologiques ont été réalisés à l’aide d’un disto X, par lasergrammétrie et par photogrammétrie.

L’entrée de la cavité est marquée par quelques grandes coupoles (fig. 6). Après, la galerie se caractérise par des formes douces. Puis l’on aboutit dans une galerie rectiligne et haute dans ses premiers mètres. La base des parois est très altérée alors que les parties hautes sont lisses. La galerie s’élargie peu à peu et devient de plus en plus basse. À la base se trouvent d’anciens gours. Le plafond est marqué par des coupoles qui se succèdent. La galerie augmente de nouveau de taille. Elle devient large et haute. Les parois sont lisses et présentent des volumes doux. La salle du Guano présente les plus gros volumes. Son plafond est constitué par de grandes coupoles, dans lesquelles s’emboîtent d’autres coupoles. Les bases des parois sont cachées par des monticules constitués de sables recouverts de minéraux phosphatés. Le calcaire fait à un aplat d’une dizaine de centimètres de largeur au niveau du sommet des monticules, traduisant un recul par rapport à sa base et par rapport à la partie non exposée aux aérosols liés au guano. Après cette salle (fig. 7), la grotte continue par une galerie large et haute, dont les parois sont lisses et dont la voute est marquée par une multitude de coupoles emboîtées (fig. 9). Puis la galerie rétrécit, sa hauteur diminue et le plafond est marqué par une succession de coupoles ayant la forme d’ogives. De l’entrée à cette partie de galerie, les coupoles présentent des dimensions variables d’une zone à l’autre et sont ou non emboîtées. Après une divergence, les galeries deviennent étroites et basses. Les coupoles sont très rares et l’on finit par aboutir, des deux côtés, sur un siphon. Post-siphons, les galeries présentent des dimensions modestes et réduites, tout en conservant une morphologie phréatique. Les 800 derniers mètres de la cavité conservent les mêmes caractéristiques géomorphologiques, avec une absence de coupoles. Ils se parcourent en quadrupédie ou en position courbée.

Des analyses minéralogiques par DRX ont été réalisées sur des échantillons de sédiments se trouvant au sol et sur des croûtes provenant des parois (fig. 5). Vingt-sept espèces minéralogiques ont été identifiées, avec une douzaine de silicates, phyllosilicates et oxy-hydroxydes, 3 sulfates, 1 carbonate et 10 phosphates. L’hexahydrite, l’epsomite et la vivianite, connus à de rares occurrences en grotte, ont été identifiés à Aziza (fig. 11). Des analyses isotopiques δ18O et δ13C ont été réalisées sur un échantillon de calcite prélevé dans la série de gours. Elles indiquent une température de cristallisation de 35 °C qui ne permet pas d’écarter une origine hydrothermale de ces spéléothèmes.

Ce travail représente la première étape dans la compréhension des mécanismes et interactions entre les espèces de chauves-souris et les grottes. La grotte Aziza permet de mettre en évidence des préférences spatiales marquées au sein d’une cavité pour chaque espèce en fonction de ses besoins éthologiques, avec des effectifs modulés selon la période de l’année (fig. 10, 11). Les chiroptères ne sont pas présents dans les parties les plus profondes de la grotte. L’étude géomorphologique de la grotte Aziza ainsi que les études sur les peuplements par les chiroptères permettent de montrer que les processus de biocorrosion liés aux chiroptères sont liés à l’éthologie des différentes espèces. En hiver, durant la période d’hibernation, celle-ci est faible. Quelques coupoles de faibles profondeurs peuvent toutefois apparaître dans les zones occupées par des espèces qui se regroupent en essaim. C’est durant les périodes d’activité et de regroupement en essaims que la biocorrosion est la plus intense. Ces regroupements entraînent le creusement de coupoles de grandes tailles qui peuvent être emboîtées les unes dans les autres mais également l’amoncèlement de déjections qui vont entraîner une biocorrosion des parois, du substratum et des sédiments exposés. Même si l’hypothèse de l’origine hypogène du karst d’Aziza ne peut pas être totalement rejetée, il est démontré ici que les coupoles de la grotte Aziza sont liées à des phénomènes de biocorrosion. Les colonies de plus grandes tailles, hors périodes d’hibernation, et les essaims les plus compacts entrainent donc les modifications géomorphologiques les plus importantes au niveau d’une grotte, comme c’est le cas dans la grotte d’Aziza dans la salle du Guano et dans la galerie qui est en amont de celle-ci. Les morphologies des parois d’une grotte occupée par des chiroptères dépend donc avant tout de l’éthologie des espèces présentes.

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Table des illustrations

Titre Fig. 1 – Location of Aziza Cave. A: location of the cave and the province of Errachidia on a map of Morocco; B: location of the cave on a map of the province of Errachidia; C: location of the cave entrance on a map with the municipality of Oued Naan; D: location of the cave entrance at the Guir River south of Tazouguert.Fig. 1 – Localisation de la grotte Aziza. A : localisation à l'échelle du Maroc de la grotte et de la province d'Errachidia ; B : localisation de la grotte à l'échelle de la Province d'Errachidia ; C : localisation de la grotte à l'échelle de la commune d'Oued Naan ; D : localisation de l'entrée de la grotte au niveau de l'oued Guir au sud de Tazouguert.
URL http://journals.openedition.org/geomorphologie/docannexe/image/21050/img-1.jpg
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Titre Fig. 2 – The entrance to Aziza Cave is located on the right bank of the Guir River and at the base of the Tazougart Plateau (photo by J.Ph. Dégletagne).Fig. 2 – L’entrée de la grotte Aziza se trouve sur la rive droite de l’oued Guir et à la base du plateau de Tazougart (photo J.Ph. Dégletagne).
URL http://journals.openedition.org/geomorphologie/docannexe/image/21050/img-2.jpg
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Titre Fig. 3 – Geological and topographical context of Jbel Chaaba. A: the plateau is built with limestone resting on Upper Cretaceous marl (after the 1:50,000 geological map of Morocco, “Tazougart”). The location of the cave is shown in red, and the location of the geological profile in (C) is shown in dotted lines; B: satellite view, showing the major structural features. The location of the cave is shown in red; C: geological cross-section along the axis of the cave.Fig. 3 – Contexte géologique et topographique du Jbel Chaaba. A : le plateau est armé de calcaires reposant sur des marnes du Crétacé supérieur (d’après la carte géologique du Maroc au 1/50 000 « Tazougart »). Le report de la cavité est indiqué en rouge, l’emplacement de la coupe en (C) est indiqué en pointillé ; B : vue satellite, avec indication des grands traits structuraux. Le report de la cavité est indiqué en rouge ; C : coupe géologique le long de l’axe de la grotte.
URL http://journals.openedition.org/geomorphologie/docannexe/image/21050/img-3.jpg
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Titre Fig. 4 – Location of the cave sections surveyed using photogrammetry and the corresponding described segments. Coordinate Systems: WGS 1984 UTM zone 30N, projection: transverse Mercator, Datum: WGS 1984, Moroccan Explorers Association, March 2019, 3335 m long, -87 m depth.Fig. 4 - Position des différentes parties de la grotte ayant fait l’objet d’un relevé photogrammétrique et des différentes sections décrites. Systèmes de coordonnées : WGS 1984 zone UTM 30N, projection : Mercator transversale, datum : WGS 1984, Association marocaine des explorateurs, mars 2019, 3335 m de long, -87 m de profondeur.
Légende 1. Cave entrance; 2. Cave development; 3. Cave development buffer.1. Entrée de la grotte ; 2. Développement de la grotte ; 3. Zone tampon du développement de la grotte.
URL http://journals.openedition.org/geomorphologie/docannexe/image/21050/img-4.jpg
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Titre Fig. 5 – Aziza Cave: location of samples collected for mineralogical analysis. Coordinate Systems: WGS 1984 UTM zone 30N, projection: transverse Mercator, Datum: WGS 1984, Moroccan Explorers Association, March 2019, 3335 m long, -87 m depth.Fig. 5 – Grotte Aziza : position des échantillons prélevés pour analyses minéralogiques. Systèmes de coordonnées : WGS 1984 zone UTM 30N, projection : Mercator transversale, datum : WGS 1984, Association marocaine des explorateurs, mars 2019, 3335 m de long, -87 m de profondeur.
Légende 1. Cave entrance; 2. Cave development; 3. Cave development buffer.1. Entrée de la grotte ; 2. Développement de la grotte ; 3. Zone tampon du développement de la grotte.
URL http://journals.openedition.org/geomorphologie/docannexe/image/21050/img-5.jpg
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Titre Tab. 1 – Climatic parameters recorded in Aziza Cave during November 2017 and October 2022.Tab. 1 – Paramètres climatologiques relevés dans la grotte Aziza en novembre 2017 et octobre 2022.
URL http://journals.openedition.org/geomorphologie/docannexe/image/21050/img-8.jpg
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Titre Fig. 6 – Aziza Cave, views of the different sections of galleries from the entrance to the Guano Chamber. A: the entrance area of the Aziza Cave, particularly on the east side (PhG1), displays several large bell holes, the formation of which has been significantly affected by past use of explosives. While the northern section of the entrance exhibits fewer bell holes, those present are considerable in volume, as revealed by photogrammetric surveys; B: immediately after entering the cave, the gallery walls are smooth (photo. H. Benani); C: narrow, high gallery. The base of the walls is weathered, while the upper part is smooth (PhG2, S2); D: narrow, tall gallery. The ceiling features a few subtly pronounced cupolas (PhG2, S2); E: the gallery widens while its height decreases. Numerous cupolas are present, though they are not very pronounced (PhG3, S3); F: gallery nearly as wide as it is high. The base is directly altered by guano, while the upper part is affected by aerosols (PhG3, S3); G: ancient rimstones, sampled for stable isotopes and U/Th dating (photo. M. Renda); H: high and wide gallery. The walls are smooth and their northern base is covered with sediments (photo. M. Renda, S4); J: the Guano Chamber, the largest in the cave, with large cupolas and nested bell holes (photo. M. Renda, S5); K: north wall of the Guano Chamber and top of the mound at the base of the walls. The wall has receded by about 10 cm from its original position prior to exposure to aerosols linked to bat droppings (photo. L. Barriquand). Figure 5 shows the location of photogrammetries (J.Ph. Deglétagne).Fig. 6 – Grotte Aziza, vues des différentes sections de galeries de l'entrée à la salle du Guano. A : zone d’entrée, côté est, le vide au-dessus des personnages est lié à l’utilisation d’explosifs. Au nord, les coupoles sont peu nombreuses mais de grand volume (PhG1) ; B : immédiatement après l’entrée de la grotte. Les parois sont lisses (S1) (photo. H. Benani) ; C : galerie étroite et haute. La base des parois est altérée, la partie haute est lisse (PhG2, S2) ; D : galerie étroite et haute. La voûte présente quelques coupoles peu marquées (PhG2, S2) ; E : la largeur de la galerie augmente, sa hauteur diminue. Les coupoles sont nombreuses mais peu marquées (PhG3, S3) ; F : galerie pratiquement aussi large que haute. La base est altérée directement par les guanos alors que la partie haute est altérée par les aérosols (PhG3, S3) ; G : les anciens gours, échantillonnés pour les isotopes stables et la datation U/Th (photo. M. Renda) ; H : galerie haute et large. Les parois sont lisses et leur base nord est recouverte de sédiments (photo. M. Renda, S4) ; J : la salle du Guano, la plus vaste de la grotte, avec de grandes coupoles et des bell holes emboîtés (photo. M. Renda, S5) ; K : paroi nord de la salle du Guano et sommet du monticule se trouvant à la base des parois. La paroi a subi un recul d’une dizaine de centimètre par rapport à son état avant exposition aux aérosols liés aux déjections des chauves-souris. La Figure 5 indique la localisation des photogrammétries (J.Ph. Deglétagne).
URL http://journals.openedition.org/geomorphologie/docannexe/image/21050/img-9.jpg
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Titre Fig. 7 – Aziza Cave, views of the different sections of galleries beyond the Guano Chamber. A and B: beyond from the Guano Chamber, a wide and high gallery. The walls are smooth and the ceiling is marked by numerous bell holes (photo. M. Renda; PhG4, S6); C: beyond the Guano Chamber, there are numerous, very distinct bell holes (PhG4, S6); D: nested bell holes beyond of the Guano Chamber; E: ceiling made up of nested bell holes beyond the Guano Chamber; F: the gallery narrows again. The ceiling is marked by ogive-shaped bell holes, and the walls are smooth (photo. H. Benani); G: bell holes just before sump 1, with a rim of apatite crust; the largest is 1.8 m long, with three small bell holes 1.5 m high (photo. H. Benani); H: section of the gallery at sump 1. The gallery is narrow with a low ceiling. The walls are jagged, with virtually no biocorrosion (photo. H. Benani); J: gallery downstream of siphon 2, the walls are jagged (photo. H. Benani). Figure 5 shows the location of photogrammetries (J.Ph. Deglétagne).Fig. 7 – Grotte Aziza, vues des différentes sections de galeries au-delà de la salle du Guano. A et B : en amont de la salle du Guano, galerie large et haute. Les parois sont lisses et le plafond est marqué par de nombreuses coupoles (photo M. Renda ; PhG4, S6) ; C : au-delà de la salle du Guano, les coupoles sont très nombreuses et très marquées ; D : coupoles emboîtées en amont de la salle du Guano ; E : plafond constitué par des coupoles emboîtées au-delà de la salle du Guano ; F : la galerie redevient étroite. Le plafond est marqué par des coupoles en forme d’ogives, les parois sont lisses (photo H. Benani) ; G : coupoles juste avant le siphon 1, avec un liseré brun d’apatite ; la plus grande fait 1,8 m de longueur, pour 3 petites coupoles à 1,5 m de hauteur (photo. H. Benani) ; H : section de la galerie au siphon 1, la galerie est étroite, de faible hauteur. Les parois sont déchiquetées, la biocorrosion est quasiment absente (photo H. Benani) ; J : galerie en aval du siphon 2, les parois sont déchiquetées (photo H. Benani). La Figure 5 indique la localisation des photogrammétries (J.-Ph. Deglétagne).
URL http://journals.openedition.org/geomorphologie/docannexe/image/21050/img-10.jpg
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Titre Fig. 8 – 3D model of most of the network before sumps 1 and 2, produced using Visual Topo (Benani et al., 2022).Fig. 8 – Modèle 3D de la partie de la majeure partie du réseau avant les siphons 1 et 2, obtenu avec Visual Topo (Benani et al., 2022).
URL http://journals.openedition.org/geomorphologie/docannexe/image/21050/img-11.png
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Titre Fig. 9 – 3D textured view of nested bell holes beyond the Guano Chamber (J.Ph. Dégletagne).Fig. 9 – Vue 3D texturée de coupoles emboîtées au-delà de la salle du Guano (J.Ph. Dégletagne).
URL http://journals.openedition.org/geomorphologie/docannexe/image/21050/img-12.jpg
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Titre Tab. 2 – Minerals identified by XRD.Tab. 2 – Minéraux identifiés par DRX.
Légende xxx = abundant; xx = present; x = traces; ? = possible occurrence.xxx = abondant ; xx = présent ; x = traces ; ? = occurrence possible.
URL http://journals.openedition.org/geomorphologie/docannexe/image/21050/img-13.jpg
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Titre 1 : Rhinolophus blasii, hiver ; 2 : Rhinopoma cystops, hiver et printemps ; 3 : Miniopterus maghrebensis, printemps ; 4 : Rhinolophus blasii, printemps ; 5 : Aselia tridents, été ; 6 : Plecotus gaisieri, été ; 7 : Rhinolophus ferrumequinum et Myoris blytii, été. Systèmes de coordonnées. WGS 1984 zone UTM 30N, projection : Mercator transversale, datum : WGS 1984, Association marocaine des explorateurs, mars 2019, 3335 m de long, -87 m de profondeur.
Légende 1. Cave entrance; 2. Cave development; 3. Cave development buffer.1. Entrée de la grotte ; 2. Développement de la grotte ; 3. Zone tampon du développement de la grotte.
URL http://journals.openedition.org/geomorphologie/docannexe/image/21050/img-14.jpg
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Titre Tab. 3 – Species richness and abundance of bats identified in Aziza cave in October. 2022.Tab. 3 – Espèces de chiroptères et abondance dans la grotte d’Aziza en octobre 2022.
URL http://journals.openedition.org/geomorphologie/docannexe/image/21050/img-15.jpg
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Titre Fig. 11 – Locations and abundance of the different bat species in October 2022. 1: Miniopterus shreibersii/maghrebensis (1000); 2: Rhinopoma cystops (230); 3: Plecotus gaisieri; 4: Rhinolophus blasii (8); 5: Myotis punicus (200); 6: Rhinolophus ferrumequinum (1) and Myotis mystacinus (8). Coordinate Systems: WGS 1984 UTM zone 30N, projection: transverse Mercator, Datum: WGS 1984, Moroccan Explorers Association, March 2019, 3335 m long, -87 m depth.Fig. 11 – Positions et effectifs des différentes espèces de chauves-souris en octobre 2022. 1 : Miniopterus shreibersii/maghrebensis (1000) ; 2 : Rhinopoma cystops (230) ; 3 : Plecotus gaisieri ; 4 : Rhinolophus blasii (8) ; 5 : Myotis punicus (200) ; 6 : Rhinolophus ferrumequinum (1) and Myotis mystacinus (8). Systèmes de coordonnées : WGS 1984 zone UTM 30N, projection : Mercator transversale, datum : WGS 1984, Association marocaine des explorateurs, mars 2019, 3335 m de long, -87 m de profondeur.
Légende 1: Cave entrance; 2 Cave development; 3 Cave development buffer.1. Entrée de la grotte ; 2. Développement de la grotte ; 3. Zone tampon du développement de la grotte.
URL http://journals.openedition.org/geomorphologie/docannexe/image/21050/img-16.jpg
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Titre Fig. 12 – Stability diagram of magnesium sulfates (epsomite–hexahydrite–kieserite series) as a function of temperature and relative humidity (based on Hill and Forti, 1997, modified). The Aziza Cave area is indicated in red at the location and time of sampling.Fig. 12 – Diagramme de stabilité des sulfates de magnésium (série epsomite-hexahydrite-kieserite) en fonction de la température et de l’humidité relative (d’après Hill et Forti, 1997, modifié). Le domaine de la grotte Aziza est indiqué en rouge, à l’emplacement et au moment de l’échantillonnage.
URL http://journals.openedition.org/geomorphologie/docannexe/image/21050/img-17.jpg
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Lionel Barriquand, Philippe Audra, Hicham Benani, Larbi Boudad, Youssef Dbiba, Jean-Philippe Dégletagne, Fernando Gázquez, Vasile Heresanu, Samira Kaddouri, Soumia Moutaouakil, Ayoub Nehili, Lalla Amina Ouzzouit et Michel Renda, « The Aziza Cave, a major karstic cave in Morocco: biocorrosion and bat ethology »Géomorphologie : relief, processus, environnement [En ligne], 32-1 | 2026, mis en ligne le 04 février 2026, consulté le 16 février 2026. URL : http://journals.openedition.org/geomorphologie/21050 ; DOI : https://doi.org/10.4000/15lgv

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Auteurs

Lionel Barriquand

Université Savoie Mont Blanc, EDYTEM, UMR 5204, Le Bourget-du-Lac, France

Philippe Audra

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