Diversity, Ecology, and Environmental Significance of Foraminifera in Al Hamama and Susah Coastal Regions, Northeastern Libya: Insights from Holocene Sediments ()
1. Introduction
Foraminifera, minute marine organisms, serve as crucial indicators of past environmental conditions due to their high sensitivity to climate variations. Their species composition, shell chemistry, and physical attributes are valuable proxies for reconstructing historical environments. Notably, the coiling direction of trochoidal foraminifera has been employed in paleoceanographic analyses. Interestingly, as far back as 1846, [1] D’Orbigny’s discovery revealed the existence of approximately 1000 undiscovered foraminifera species within modern oceanic realms. Regional studies in the Mediterranean Sea have comprehensively documented the prevalence and distribution of shelf foraminifera. These investigations have unveiled geographical disparities in shelf fauna composition. The fauna exhibits distinctive microhabitat zonation within the fine-grained sediments of the Adriatic Sea and the Gulf of Lions, influenced by factors such as food availability and oxygen penetration into the sediment [2] - [7] . Our research endeavors to contribute novel insights into the diversity, distribution patterns, and ecological aspects of recent cool-water carbonate taxa in the Western Mediterranean. By establishing correlations between benthic foraminiferal faunas and environmental parameters, we aim to reconstruct historical environmental fluctuations, including quantitative sea-level reconstructions.
The environmental characteristics of the Mediterranean Sea are profoundly influenced by its geographical proximity to land. The narrow connection to the Atlantic Ocean significantly restricts tidal dynamics. A distinct and instantly recognizable feature of the Mediterranean is its vivid blue hue. Regarding hydrology, the Mediterranean experiences a substantial imbalance between evaporation and precipitation, as well as river runoff, which plays a pivotal role in determining the basin’s water balance [8] . The eastern sector of the Mediterranean is characterized by notably high rates of evaporation, leading to declining water levels and a consequent rise in salinity as one moves eastward. At a depth of 5 meters, the average salinity registers at 38 Practical Salinity Units (PSU). Notably, the Mediterranean Sea’s deepest point maintains a temperature of 13.2 degrees Celsius. Furthermore, the Mediterranean Sea contributes a substantial volume of water to the Atlantic Ocean, estimated at approximately 70,000 cubic meters per second, or an annual flow rate of 2.2 × 1012 cubic meters (7.8 × 1013 cubic feet) [9] [10] [11] [12] . The Mediterranean Sea, covering an expanse of approximately 2,500,000 square kilometers (970,000 square miles), represents just 0.7% of the Earth’s total oceanic surface. Despite its relatively modest size, its connection to the Atlantic Ocean through the narrow Strait of Gibraltar spans a mere 14 kilometers (9 miles) in width. This maritime domain is punctuated by numerous islands, some of which are of volcanic origin, with Sicily and Sardinia ranking as the largest in terms of land area and population.
The Mediterranean’s average depth reaches 1500 meters (4900 feet), with the deepest point, recorded at 5109 meters (16,762 feet), located in the Calypso Deep within the Ionian Sea. Geographically, the Mediterranean is situated between the latitudes of 30 V and 46˚ North and the longitudes of 6˚ and 36 V East. Its elongated extent stretches approximately 4000 kilometers (2500 miles) from west to east, spanning from the Strait of Gibraltar to the Gulf of Alexandretta along Turkey’s southern coast. The north-south axis of this maritime expanse exhibits significant variability, contingent upon the specific shoreline considered and the inclusion of only direct routes. The shortest navigational distance between the multinational Gulf of Trieste and the Libyan shores of the Gulf of Sidra measures approximately 1900 kilometers (1200 miles). The Mediterranean climate, characterized by mild winters and warm summer water temperatures, derives its nomenclature from the preponderance of precipitation during the cooler months. Coastal areas bordering the Mediterranean are subject to substantial maritime influences, while the southern and eastern coastlines are closely aligned with arid desert regions situated a short distance inland. [9] [11] [12] .
2. Study Area
The Mediterranean Sea is made up of four major water bodies. The surface waters are made up of incoming Atlantic Water. At intermediate depths, Levantine Intermediate Water, which forms in the eastern Mediterranean Sea, is found. Both the Western and Eastern Mediterranean Deep Waters, which originate in the Gulf of Lions and the Adriatic and Aegean seas, bathe the basins with water that is less than 600 meters deep [12] [13] [14] [15] . The Susah and Al Hamamah Beaches in the Mediterranean Sea are two locations where the study area is situated in northeastern Libya as you see in Figure 1.
3. Materials and Methods
In the present investigation, five surface sediment samples were acquired from the designated locations. The estimation of sample volumes involved a wet-sieving process utilizing a 63 μm sieve. Subsequently, a portion of the material retained on the 63 μm sieve was subjected to drying at 60˚C. The samples underwent wet-sieving to ascertain the weight percentages within specific size fractions, namely >1000 μm, 1000 μm - 500 μm, 500 μm - 200 μm, 200 μm - 100 μm, 100 μm - 63 μm, and the <63 μm fraction. This meticulous procedure was conducted to elucidate the grain-size distribution of the sediment samples.
![]()
Figure 1. Shows the locations of the study areas. Google map.
4. Results
The results revealed that Amphisteginidae, Elphiididae, Haauerinidae, Mississippiinidae, Peneroplidae, and Soritidae are the only documented families. Considering the outcomes, the majority of benthic foraminifera species belong to the Haurinidae family, as seen in Figure 2.
In addtion, nine benthic foraminifera samples were collected: Amphistegina lobifera, Eliphidium crispum, Sigmoilinita tenuis, Sorites orbiculus, Stomatorbina concetrica, Peneroplis planatus, Pseudotriloculina rotunda, Pyrgoella sphaera, and Triloculina schreberiana . The highest species are Eliphidium crispum, and Amphistegina lobifera (Figure 3).
Only one family of planktonic foraminifera was found within the studied samples (Figure 4), which is the Globigernidae family. Orbulina universa is the only present species of the family (Figure 5), and no other species were found.
5. Discussion
Biostratogphy and Paleoenviroment Impilication
Benthic Foraminifera
Amphistegina lobifera thrives in warm and shallow waters, typically found at
![]()
Figure 2. Shows the different families of benthic foraminifera.
![]()
Figure 3. Shows the species of benthic foraminifera.
![]()
Figure 4. Shows the family of planktonic foraminifera.
![]()
Figure 5. Shows the species of planktonic foraminifera.
depths of 50 meters (Figure 6). They mainly inhabit the seafloor areas between the coastline and coral reefs. Their tests are harder compared to other more fragile foram tests, making it possible for them to survive in water that is agitated by waves, found in quaternary by Larsen, A. R., 1976. Eliphidium crispum compared to the cold-water specimens (200 m) found by Cushman and Grant in 1927, this fauna is known from brackish-water paleoenvironments, found in quaternary [12] [16] [17] in the warm waters of Mexico. Sigmoilinita tenuis is a species of foraminifera that has been found from the Upper Aptian to the lower Albian stages of the Cretaceous period up to the recent times in Araripe [18] [19] . Sorites orbiculus Anthropogenic nutrient pollution is causing increased growth of epiphytic algae on seagrasses and macroalgae in the subtidal zone [20] Stomatorbina concetrica During the early stages of development, some marine organisms have an affinity for shallow environments that are associated with coralline algae (early Oligocene to recent). [21] Peneroplis planatus Lives under plants on the sand, preferring only sand. Light depth affects distribution beyond 40 m [22] [23] Pseudotriloculina rotunda is indicative of coastal lagoons, marshes, and other partially-barred brackish environments [24] . Pyrgoella sphaera this species is an Epinfaunal species found in well-ventilated lower bathyal and abyssal regions of the Mediterranean Sea, indicative of oligotrophic to mesotrophic environments [25] [26] . Triloculina schreberiana this species indicates that the period was marked by several sub-environments that were favorable to a variety of species. This could suggest the occasional opening of the barrier, heightened storm activity, or other factors that caused fluctuations in salinity and water depth during this time [27] .
Planktonic Foraminifera
Orbulina universa was first found in the N9 zone during the Langhian stage and still exists to date. It is distributed globally from the Equator to subpolar regions, in both low and high latitudes. This means that it can be found in the sunlit waters of the euphotic zone in oceanic waters that are shallower than 100 m. In laboratory experiments, it has been observed to tolerate temperatures ranging from 17˚C - 23˚C [28] [29] [30] [31] [32] .
Paleobathymetric indicators
![]()
Figure 6. Age distribution of the planktonic and benthic foraminifera and their relative abundance (H-High).
The delineation of water depth is ascertained through the presence of benthic and planktonic foraminifera. These foraminifera, encompassing both the benthic and planktonic varieties, exhibit a consistent occurrence within the depth interval spanning from 50 to 100 meters beneath the sea’s surface, as seen in Figure 7.
Anthropogenic impacts
In recent investigations, numerous benthic foraminifera originating from the Paleogene and Neogene epochs were unearthed along the coastal region, notably including specimens such as Nummulite fabianii and Numulite Lyelli [12] . These foraminifera represent reworked specimens likely originating from geological outcrops within the valley region, such as caves in the Darna and Al Baydah Formations.
One of the primary sources of potable freshwater is found within karst formations. This is attributed to the intrinsic porosity and permeability of the rock, enabling the diffusion of water throughout the entire mass of carbonate rock, rather than being confined solely to the principal discontinuity networks. The phenomenon popularly recognized as “acid rain” results from a combination of both wet and dry deposition processes from the atmosphere, typically characterized by elevated levels of nitric and sulfuric acids. This environmental issue has been exacerbated by recent increases in atmospheric carbon, leading to the creation of additional karst features and intensified acid rain, with direct consequences for the carbonate biogenic fauna present in the coastal areas. Subsequently, carbonate rocks began to undergo degradation, thereby compromising the preservation of these fossil remains by human-induced factors as you have seen in Figure 8.
The observed high-productivity indicators within the biocoenosis and their notable distinctions from the thanatocoenoses can be correlated with contemporary anthropogenic eutrophication within this region, primarily induced by the influx of sewage and litter due to acts of terrorism within the coastal areas of A Hamamah and Susah. Initial data from sediment cores obtained in this area, depicting benthic foraminiferal faunas during the preindustrial era, substantiate the notion of anthropogenic influences on the benthic ecosystems in A Hamamah and Susah. These faunas reveal the presence of only scant infaunal taxa.
![]()
Figure 7. Displays the range of water depths for benthic and planktonic foraminifera.
![]()
Figure 8. Displays a doline located in the Darnah Formation, which is of Middle Eocene age and is situated in NE Libya.
Paleontological Taxonomy
1) Benthic Foraminifera
Amphisteginidae Cushman, 1927 [33]
Amphistegina d’Orbigny, 1826 [34]
Amphistegina lobifera Larsen, 1976 [35] (Figure 9(a))
Elphidiidae Galloway, 1933 [36]
Elphidium de Montfort, 1808 [37]
Eliphidium crispum Linnaeus, 1758 [38] (Figure 10(a))
Hauerinidae Schwager, 1876 [39]
Sigmoilinita Seiglie, 1965 [40]
Sigmoilinita tenuis Cžjžek, 1848 [41] (Figure 9(e))
Pseudotriloculina Cherif, 1970 [42]
Pseudotriloculina rotunda d’Orbigny in Schlumberger, 1893 [43] (Figure 10(e))
Pyrgoella Cushman, and White, 1936 [44]
Pyrgoella sphaera d’Orbigny, 1839 [45] (Figure 9(d))
Triloculina d’Orbigny, 1826 [34]
Triloculina schreiberiana d’Orbigny, 1839 [45] (Figure 10(c))
Soritidae Ehrenberg, 1839 [45] in Loeblich, and Tappan, 1987 [46]
Sorites Ehrenberg, 1839 [45] in Loeblich, and Tappan, 1987 [46]
Sorites orbiculus Forsskål in Niebuhr, 1775 [47] (Figure 9(c))
Mississippinidae Saidova, 1981 [48]
Stomatorbina Dorreen, 1948 [49]
Stomatorbina concentrica, [21] Parker, and Jones, 1864 (Figure 9(b))
Peneroplidae Schultze, 1854 [20]
Peneroplis de Montfort, 1808 [37]
Peneroplis planatus Fichtel, and Moll, 1798 [50] (Figure 10(b))
2) Planktonic Foraminifera
Globigerinidae Carpenter Parker, and Jones, 1862 [51]
Orbulina d’Orbigny, 1839 [45]
Orbulina universa d’Orbigny, 1839 [45] (Figure 10(d))
![]()
Figure 9. Benthic foraminifera species: (a) Amphistegina lobifera, (b) Stomatorbina concentrica, (c) Sorites orbiculus, (d) Pyrgoella sphaera, (e) Sigmoilinita tenuis.
![]()
Figure 10. Benthic and planktonic foraminifera species: (a) Eliphidium crispum, (b) Peneroplis planatus, (c) Triloculina schreberiana, (d) Orbulina universa, (e) Pseudotriloculina rotunda.
6. Conclusions
The study conducted along the coastline of northeastern Libya’s Al Hamama and Susah areas has provided valuable insights into the Holocene benthic foraminifera assemblage and paleoenvironmental conditions in this region. Nine benthic foraminifera species, including Amphistegina lobifera, Eliphidium crispum, Sigmoilinita tenuis, Sorites orbiculus, Stomatorbina concetrica, Peneroplis planatus, Pseudotriloculina rotunda, Pyrgoella sphaera, and Triloculina schreberiana, were identified, with Eliphidium crispum and Amphistegina lobifera being the most prominent species. These foraminifera species exhibited unique ecological preferences, shedding light on the environmental conditions of the Susah and Al Hamamah coastal regions during the Holocene.
Furthermore, the presence of Orbulina universa, a planktonic foraminiferal species, in the region provides additional insights into the paleoenvironment, as this species is indicative of specific water depths and temperature ranges. The study’s findings contribute to the broader field of paleoceanography and environmental reconstruction, emphasizing the significance of foraminifera as valuable proxies for studying past environmental changes. The study also discussed the impact of anthropogenic factors on the benthic ecosystems in the A Hamamah and Susah coastal areas, including the presence of reworked foraminifera specimens and the influence of karst formations, acid rain, and eutrophication. These human-induced factors have had notable effects on the biogenic fauna and ecosystem dynamics in the study area. Overall, this research enhances our understanding of the paleoenvironment and ecological dynamics in the Susah and Al Hamamah coastal regions and underscores the importance of studying foraminifera in reconstructing past environmental changes.
Acknowledgements
I express my sincere gratitude for the generous financial support provided, including funding for the project and photography by Dr. Ishamn. Special thanks are extended to Dr. Brendan for the invaluable funding assistance. Additionally, my appreciation goes to the entire Kansas Geological Survey for their support throughout this endeavor.