Coastal Caves Research Articles

Last interglacial and MIS 9e relative sea-level highstands in the Central Mediterranean: a reappraisal from coastal cave deposits in the Cilento area, Southern Italy

A revaluation of the relative sea-level (RSL) indicators in the Baia di Infreschi (Cilento, Southern Italy) supported by new 30 U/Th dating on speleothems indicates that the upper level of Lithophaga burrows identified by Bini et al. (2020) at ∼9 m a.s.l. and correlated to the Last Interglacial (LIG) highstand should be referred to the highstand of the MIS 9e, whereas the local RSL for the highstand of the LIG is now reassessed at 5.3 ± 0.18 m a.s.l. The upper level of the Lithophaga marker can be followed for ∼12 km along the coast, suggesting a substantial absence of important relative tectonic movements. In the Baia di Infreschi an additional marine indicator, a notch sealed by a flowstone dated ∼110 ka, indicates several phases of RSL stationing below the maximum highstand of the LIG. The presence of flowstones as low as 2 m a.s.l. dated to the MIS 7 shows that the highstand of MIS 7 was probably below the present sea level. All these evidences allow us to reassess the stratigraphy of some archaeological caves in the area, indicating that the sedimentary successions preserved there are older than what was previously believed.

Earliest known funerary rites in Wallacea after the last glacial maximum

The insular region of Wallacea has become a focal point for studying Pleistocene human ecological and cultural adaptations in island environments, however, little is understood about early burial traditions during the Pleistocene. Here we investigate maritime interactions and burial practices at Ratu Mali 2, an elevated coastal cave site on the small island of Kisar in the Lesser Sunda Islands of eastern Indonesia dated to 15,500–3700 cal. BP. This multidisciplinary study demonstrates extreme marine dietary adaptations, engagement with an extensive exchange network across open seas, and early mortuary practices. A flexed male and a female, interred in a single grave with abundant shellfish and obsidian at Ratu Mali 2 by 14.7 ka are the oldest known human burials in Wallacea with established funerary rites. These findings highlight the impressive flexibility of our species in marginal environments and provide insight into the earliest known ritualised treatment of the dead in Wallacea.

Factors influencing the evolution of sandstone sea caves: A case study from the Apostle Islands National Lakeshore (Lake Superior, USA)

Caves in coastal cliffs in the Apostle Islands were analyzed for factors controlling their origin and evolution. Even though the Bayfield Group quartz sandstones were found to be of relatively low tensile strength, the traditional explanation attributing speleogenesis to localized zones of lithological and tectonic weakness does not adequately explain all geomorphic features of the caves. The caves were found to be formed by coalescence of smaller arcade-shaped cavities serially developed along subhorizontal discontinuities. In concordance with the previously formulated “arcade principle”, positions and shapes of the cavities are defined by areas of reduced stress within the gravity-induced stress field. Evacuation of material from the rock massif can be attributed to wave action including the effect of water-pressurized air, and frost action. Compound cavities above the discontinuities tend to form “higher-order” arcade-like cavities/caves while those beneath more resistant strata rather develop into elongated overhangs similar to ordinary coastal notches. Propagation of the largest cavities, formed along steeply dipping joints and faults, is attributed to mass wasting and roof collapses. Similar examples of discontinuity-related cavities in coastal settings, suspectedly also controlled by gravity-induced stress distribution, can be found worldwide, being mostly concentrated to areas covered by ice sheets in the Pleistocene. The interplay between post-glacial isostatic uplift and Holocene lake-level rise is responsible for the development of mature forms of coastal caves in the Apostle Islands where present cliffs are estimated to have been exposed to the effects of wave action for the last 3–5 ky.

40Ar/39Ar Age Constraints on MIS 5.5 and MIS 5.3 Paleo‐Sea Levels: Implications for Global Sea Levels and Ice‐Volume Estimates

AbstractWe integrate 10 new with five published 40Ar/39Ar age determinations, both on primary volcanic deposits and on detrital sanidine, which provide precise geochronologic control on the Marine Isotope Stage (MIS) 5.5 and MIS 5.3 sea‐level indicators that occur at three coastal caves in a tectonically stable region of the central Tyrrhenian Sea of Italy. The age of a Strombus‐bearing bioclastic conglomerate, associated with a tidal notch occurring at 9.5 m a.s.l. at Cape Circeo, is constrained to between 121.5 ± 5.8 and 116.2 ± 1.2 ka. Moreover, backbeach deposits intercalated in the sedimentary filling of Guattari and Capre coastal caves are directly correlated with a tidal notch at ∼2.5 m associated with another bioclastic conglomerate at Cape Circeo and dated to 110.4 ± 1.4–104.9 ± 0.9 ka. The latter deposit is also correlated with the adjacent marine terrace, occurring at 3–5 m on the coast between Capes Circeo and Anzio, for which a maximum age of 100.7 ± 6.6 ka was previously reported. These data provide evidence for a maximum sea level around 9.5 m above the present sea level and a duration of MIS 5.5 highstand until 116 ka, in agreement with estimates from other regions in the world. In contrast, they suggest a maximum sea level during MIS 5.3 highstand that is similar to the present level, and only ∼7 m lower than the MIS 5.5 highstand, challenging the reconstructions of the MIS 5 ice‐sheet volumes and derived global sea levels that are based on benthic oxygen isotope records.

Paleokarst coastal caves at Torricelle Hills (Lessini Mountains, Venetian Prealps, Italy)

This paper describes a set of paleokarst caves at Torricelle Hills near Verona (Southern Alps, Italy.) At this locality, erosional surfaces and paleokarst cavities show that sedimentation of late Paleogene neritic limestones was interrupted by subaerial exposure. Karst features developed during a phase of marine regression that started after the early Oligocene and ended in the mid Miocene. These caves were originally completely filled by iron oxides- and hydrated oxides-rich paleosol sediments (ochre) that, for centuries, have been mined for pigments. Mining activity emptied the caves, leaving the voids and related shapes mostly intact; as a result, the original morphologies have been exhumed, making these caves a rare example of explorable paleokarst. These “ochre caves” were mapped in a series of surveys over a few years. The exploration of overall 4.5 km of accessible passages in four caves yielded a wealth of information on speleological features, stratigraphy, paleontology, and paleogeography, and here we exploit this information to infer the genesis of these unusual caves. Their evolution started in phreatic conditions, characterized by very slowly moving or still waters that led to the formation of solution facets. A vadose phase of development ensued, followed by infilling by reworked soil-derived sediment and associated paragenetic modifications. Sediment accumulation ended with the complete fossilization of the caves under epiphreatic conditions. Siliciclastic and carbonate sediments containing littoral fossils indicate that the caves developed in the vicinity of a coast, and that they were subject to marine ingression. Overall, these paleokarst coastal caves seem to be a fossilized example, well preserved and explorable, of the Carbonate Island Karst Model on larger islands. We interpret these caves as conduits that drained the freshwater lens in a spatially limited carbonate peninsula that existed in this part of the Lessini paleocoastline between the Oligocene and the Miocene.

Sea Caves and Other Landforms of the Coastal Scenery on Gozo Island (Malta): Inventory and New Data on Their Formation

Sea caves are a type of cave formed primarily by the wave action of the sea. The coastal scenery of the Gozitan coast is very interesting in that sea caves and other coastal landforms, such as sea arches, develop at the sea level. We mapped seventy-nine semi-submerged sea caves opening at the sea level, five completely submerged sea caves, seven sea arches, one sea stack, and one shelter around the coast of Gozo, mainly in the Western and Eastern parts of the island, due to favorable lithological and topographical conditions. Additionally, we surveyed the topography of the emerged part of nine sea caves using the iPhone build-in LiDAR sensor, and eight sea caves in the submerged part using SCUBA equipment. This inventory represents the most detailed example of a database of coastal caves and related forms in the Mediterranean, mainly sourced from a swimming survey along the entire island. Thanks to the combination of outputs of the above-water emerged and submerged surveys, we defined three types of semi-submerged sea caves: (i) box caves, (ii) joint caves, and (iii) complex caves. Moreover, we added a cave-like landform above the sea level on calcarenites called shelter, or a little extended notch deeply carved into the cliff. The shape mainly depends on the structural and lithological setting of sea cliffs. In the Western sector of the island, we also discovered the only sea cave in Gozo, measuring 122 m in length and 10 m in width, with its floor developing above the mean sea level. This cave base is of interest due to rounded landforms related to marine erosion. In the innermost part of the cave, there is also a beach with rounded pebble at an elevation of about 7 m asl. Considering the tectonic stability of the island, it could be possibly related to the MIS 5.5 highstand.

Neanderthal bones collected by hyena at Grotta Guattari, central Italy, 66–65 ka: U/Th chronology and paleoenvironmental setting

After eight decades since its discovery in 1939, new investigations have been undertaken at Grotta Guattari (Latium, central Italy), a coastal cave by the Tyrrhenian Sea coast and one of the iconic sites of the Italian prehistory, as it yielded an almost complete skull and other remains of Neanderthals. The new excavations of the innermost and untouched cave deposits resulted in an outstanding amount of mammal bones, 40 out of which attributable to Neanderthal, including new large portions of cranial remains. Preliminary taphonomic hints and the collected stratigraphic evidence strongly indicate that the impressive accumulation of the large mammal bones was the work of spotted hyena, in a period in which human frequentation was really sporadic or even completely absent. The new acquired U/Th chronology of Grotta Guattari speleothems provided new constraints for reconstructing the sedimentary and paleoenvironmental history of the archaeological successions and human remains. The accumulation of terrestrial sediments started at ∼112 ka, immediately after the end of the Last Interglacial sea-level highstand (∼116 ka). However, the hyena frequentation, and thus the bone accumulations, occurred several thousands of years after and lasted for a very short time interval, precisely between slightly before 66 ka and 65 ka. The cave became abandoned by hyena after ∼65 ka and before ∼59 ka, because of the cave obstruction and/or the altered environmental conditions related to the Heinrich Event 6 (∼64–60 ka). The regional paleoclimatic records indicate severe conditions during the short interval of the hyena frequentation. In contrast, though providing evidence of open and arid environments, the faunal assemblage and the pollen from Grotta Guattari reveal that the local conditions were less severe, likely because of the mitigating effect of the Tyrrhenian Sea. In the framework of the Italian findings, Grotta Guattari results the richest and better chronologically constrained site of Neanderthal remains, posing it as one of the rare sites of the European prehistory that allows putting into the context an extraordinary large sample of the population of Neanderthals, and of other large mammals, in a very narrow and precisely dated temporal interval of the early Pleniglacial.

Making Points: The Middle Stone Age lithic industry of the Makgadikgadi Basin, Botswana

Studies of early human occupation of Africa over recent decades have profoundly changed how we understand our early ancestors, their inventiveness and adaptability. The spread of Homo sapiens to new environmental settings, the expansion of diet breadth, the development of more complex technology and the use of personal ornaments have all been recognized at well-documented Middle Stone Age (MSA) cave and shelter sites, particularly along the South African coast. This paper addresses two under-represented aspects of MSA research: open-air sites and the African interior. We present here recent surveys and excavations in Ntwetwe Pan, Botswana, a remote, open landscape, that formerly contained a vast palaeolake. The five excavated sites yielded assemblages composed exclusively of silcrete, a locally available raw material. The lithic industry at these sites was deposited during dry periods following palaeolake high stands dating to c.128–81 ka and c. 72–57 ka. This industry, characterized by a limited toolkit dominated by highly retouched unifacial and bifacial points, is not previously documented but shows similarities to dated MSA sites of equivalent age in north-western Botswana and Zimbabwe. Combined, these exposed open-air sites document the successful MSA adaptation to a hydrologically dynamic, interior landscape and arguably display MSA behavioural patterns that complement and balance the more well-documented perspectives from coastal cave and shelter sites.

Mineralogical and Sedimentological Characterization of the Clay-Rich Sediments from Ases Cave (Cova Dets Ases, Mallorca, Spain): Origin and Classification

The Mallorca coastal caves present large amounts of speleothems that have been studied for decades. However, the sedimentary deposits also present in these cases have not been given the same attention. This work is the first study entirely focused on these deposits, specifically the ones found in the Ases cave. These deposits are formed by clay minerals (illitic phases, kaolinite, smectite, and chlorite), calcite and quartz, and minor proportions of dolomite, albite, orthoclase, hematite, and goethite. The grain size and the electron microscopy studies suggested the presence of different sedimentation processes (bedrock degradation, creep or saltation, and suspension) and different origins (authigenic and detrital origins) for the different sediments. Based on these differences, two types of deposits were characterized: autochthonous and allochthonous deposits. The first ones are located on the floor of chambers and corridors in subaqueous zones, indicating the stability of the mixing zone (and therefore the sea level) over time. The second ones appear filling voids on the walls and the ceiling in the terrestrial zone, evidencing the filling of the cavity in the presence of water (during a wet period). These results are very important to complete the understanding of the caves and their evolution and support the relevance of these materials in paleoenvironmental studies.

Quaternary Evolutionary Stages of Selinitsa Cave (SW Peloponnese, Greece) Reveal Sea-Level Changes Based on 3D Scanning, Geomorphological, Biological, and Sedimentological Indicators

Significant evolutionary stages of Selinitsa Cave (SW Peloponnese, Greece) were revealed by 3D mapping, as well as geomorphological study of the cave and the nearby landscape. Four marine terraces were identified in the area of the coastal cave at 6, 10.7, 16.6, and 30–32 m above sea level (asl), with the terrace at 16.6 m representing Marine Isotope Stage (MIS) 5. The widest karstified space of Selinitsa Cave clusters between 15.73 and 18.05 m above sea level (asl), with the peak lying at 16.4 m asl, corresponding to the level where the phreatic/epiphreatic zone was stable for a sufficient period of time. A tidal notch at 16.4 m asl at the cave entrance is correlated to the marine terrace at 16.6 m. Both features correspond to the sea-level stand at which intense karstification occurred. The tidal notch bears a horizontal arrangement of Lithophaga borings at the vertex. Sedimentological investigation of the Selinitsa fine-grained deposit revealed the paleohydrologic regime of the cave. It is characterized by “slack-water” facies, indicating very low water flow speeds, whereas the thickness of the deposit points to stable hydrological conditions for prolonged periods. The cave sediment height of 18.8 m asl indicates a flooding level higher than sea level. The overlying Plattenkalk flysch is most probably the major source of detritus, and the predominance of authigenic dolomite (>98% modal in the carbonate fraction) indicates a hyposaline environment related to mixing of sea water with percolating fresh water. The approach of this study shows the significance of 3D mapping, bio-geo-Relative Sea Level (RSL) indicators, and sedimentology in deciphering the paleogeographic evolution of coastal karstic systems and subsequently defining the paleoclimate regime of coastal areas in Greece and the eastern Mediterranean during the Late Quaternary.

A New Species of Pseudocyclopiidae (Crustacea, Copepoda, Calanoida) From an Anchialine Environment of South-Eastern Italy

A new species of stygobiont copepod (Stygocyclopia badinoi sp.nov.) is described from the anchialine environment of Zinzulùsa cave (Castro, Italy). It is the first Pseudocyclopiidae (Copepoda, Calanoida) to be reported from Italian fauna and the second one reported from the Mediterranean area. The current species is characterized by the largest body size among congeners and by a general lacking of spiny fields on the cuticle of Urosome and P5. The genus has representatives in anchialine environments of coastal caves in Australia, New Caledonia, Philippines, Canaries, and Balearic islands, and the present Mediterranean report is a relict station well included in the frame of an ancient and widespread geographic distribution of ancestral Pseudocyclopiidae along the Tethys Ocean coastlines.

An integrative re-evaluation of Typhlatya shrimp within the karst aquifer of the Yucat\xe1n Peninsula, Mexico

The Yucatán Peninsula, Mexico is a carbonate platform well-known for extensive karst networks of densely stratified aquifer ecosystems. This aquifer supports diverse anchialine fauna, including species of the globally distributed anchialine shrimp genus Typhlatya (Atyidae). Four species (T. campecheae, T. pearsei, T. dzilamensis and T. mitchelli) are endemic to the Peninsula, of which three are federally listed in Mexico. This first integrative evaluation (i.e., molecular, morphological, broad geographic and type locality sampling, and environmental data) of Yucatán Typhlatya reveals considerable species identity conflict in prior phylogenetic assessments, broad species ranges, syntopy within cave systems and five genetic lineages (of which two are new to science). Despite sampling from the type locality of endangered T. campecheae, specimens (and molecular data) were indistinguishable from vulnerable T. pearsei. Ancestral/divergence reconstructions support convergent evolution of a low-salinity ancestor for a post-Paleogene arc Yucatán + Cuba Typhlatya clade within the anchialine Atyidae clade. A secondary adaptation for the coastal-restricted euryhaline (2–37 psu), Typhlatya dzilamensis (unknown conservation status) was identified, while remaining species lineages were low-salinity (< 5 psu) adapted and found within the meteoric lens of inland and coastal caves. This study demonstrates the need for integrative/interdisciplinary approaches when conducting biodiversity assessments in complex and poorly studied aquifers.

Mapping and U[sbnd]Th dating of the world's deepest blue hole (South China Sea): Implications for its timing, possible volcanogenic origin, and Pleistocene eolianites in the Xisha Islands

The Sansha Yongle Blue Hole (SYBH) is the deepest (301.19 m) blue hole known in the world and is a water-filled karst opening in the intertidal reef flats of the eastern Yongle Atoll, Xisha Islands, South China Sea. It is differentiated from the surrounding environment by its deep blue colour as observed when viewed from above. The SYBH exhibits extremely rare karst networks and speleothems and differs from the blue holes of the Bahamas and Bermuda, indicating a different development process. Here, we present the morphology and UTh ages of the SYBH, which document the evolution of the coastal cave over time. Morphology and lithostratigraphy indicate that the hole resulted from dissolution via ascending acidic water/gas followed by subsequent collapse. The adjacent volcanoes surrounding the eastern Yongle Atoll are the most likely source of these ascending fluids. UTh ages of the cemented carbonate sand underlying the entrance constrain an upper limit of the opening time of the SYBH to be up to 111.7 ± 9.5 kyr BP. Deeply submerged speleothems at −116 m determine the lower collapse time of the SYBH to be 29.16 ± 0.17 kyr BP. The SYBH probably formed due to the upward release of volcanogenic acid water/gas through low-lying unconsolidated carbonate sediments, followed by buoyant collapses due to a 40-m fall in the sea level during 31–29 kyr BP. As the sea level rose to −15 m in the early Holocene, corals grew in the cave opening since 8.58 kyr BP and surrounded the entrance for the SYBH.

Coastal heritage: exploring caves and associated indigenous knowledge in the Lanta Bay (Southern Thailand)

This article presents the preliminary results of community-based archaeological and ethnographic research on the maritime heritage landscape along the Lanta Bay involving the Urak Lawoi sea nomads and with a focus on caves and rock art. It documents several newly-discovered rock art sites as well as the relationships local groups entertain, or not, with these caves. By doing so, it wishes to investigate the various social groups direct or indirect involvement in regional network through time: merchants, sea nomads, fishermen, estuarine and inland forest groups, etc. In a matter of fact, until now, research has mostly focused on lowland riverine ports, foreign merchants and to long-distance connections. In comparison, much less attention has been paid to the many other local groups for whom offshore or coastal caves, islands and mangrove forest in estuaries constituted places for resource procurement, homes, landmarks, temporary shelters or ritual places. This project intends aims to document these groups’ contribution of all to maritime history and the landscape heritage.

Mermaid Toponyms in the West Indies: Traditional and non-traditional names

The study brings together fourteen landscape place names with the element ‘mermaid’ from the West Indies. The locations range from a coastal cave in Bermuda, in the north, to an inland pool in Trinidad, in the south. Some of these names are linked to regional folklore; some are arguably confected names invented, for instance, to encourage tourism. The author asks what markers can help us distinguish between folklore and confected names and ends with a list of other mermaid place names in Africa, the Pacific and America that might have their origins in indigenous or colonial era folklore.

Submerged Speleothems and Sea Level Reconstructions: A Global Overview and New Results from the Mediterranean Sea

This study presents a global overview of the submerged speleothems used to reconstruct paleo sea levels and reports new results from two stalactites collected in the Mediterranean Sea. Coastal cave deposits significantly contributed to the understanding of global and regional sea-level variations during the Middle and Late Quaternary. The studied speleothems cover the last 1.4 Myr and focused mainly on Marine Isotope Stages (MIS) 1, 2, 3, 5.1, 5.3, 5.5, 7.1, 7.2, 7.3 and 7.5. The results indicate that submerged speleothems represent extraordinary archives that can provide detailed information on former sea-level changes. The two stalactites collected in the central Mediterranean Sea, at Favignana and Ustica islands (Sicily, Italy), are both characterized by continental, phreatic or marine layers. The U-Th and 14C ages of the new speleothems provide results of great interest for relative sea-level changes over the last 1000 years.

Monsters in the dark: systematics and biogeography of the stygobitic genus Godzillius (Crustacea: Remipedia) from the Lucayan Archipelago

Remipedia is a stygobitic group commonly associated with coastal anchialine caves. This class consists of 12 genera, ten of which are found within the Lucayan Archipelago. Herein, we describe a new species within the genus Godzillius from Conch Sound Blue Hole, North Andros Island, Bahamas. Godzillius louriei sp. nov. is the third known remipede observed from a subseafloor marine cave, and the first from the Godzilliidae. Remipedes dwell within notoriously difficult to access cave habitats and thus integrative and comprehensive systematic studies at family or genus level are often absent in the literature. In this study, all species of Godzillius are compared using morphological and molecular approaches. Specifically, the feeding appendages of G. louriei sp. nov., G. fuchsi Gonzalez, Singpiel &amp; Schlagner, 2013 and G. robustus Schram, Yager &amp; Emerson, 1986 were examined using scanning electron microscopy (SEM). Species of Godzillius are identified based on the spines of maxilla 1 segment 4 and by the denticles on the lacinia mobilis of the left mandible. A molecular phylogeny using the mitochondrial 16S rRNA and nuclear histone 3 genes recovered G. louriei sp. nov. within the Godzillius clade and 16S genetic distances revealed a 13–15% difference between species of Godzillius.

Last interglacial sea-level history from speleothems: a global standardized database

Abstract. Speleothems (secondary cave carbonate precipitates) are archives of valuable information for reconstructing past sea levels as they are generally protected from weathering and erosion by their location and can be dated with U-series methods. Two main categories of speleothems are recognized as sea-level indicators: phreatic overgrowth on speleothems (POSs) and submerged vadose speleothems (SVSs). POSs have the great advantage that they precipitate on preexisting supports (vadose speleothems or cave walls) at a brackish water level equivalent to sea level when air-filled chambers of coastal caves are flooded by rising sea. SVSs are also useful, but sea level is inferred indirectly as periods of growth provide constraints on maximum sea-level positions, whereas growth hiatuses, sometimes difficult to observe, may indicate times when cave passages are submerged by sea highstands; hence they record minimum sea-level elevations. Here we describe a compilation that summarizes the current knowledge of the complete last interglacial (in its broadest sense from ∼ 140 to 70 ka, also known as marine isotope stage (MIS) 5) sea level captured by speleothems. We used the framework of the World Atlas of Last Interglacial Shorelines (WALIS), a comprehensive sea-level database, to provide a standardized format in order to facilitate scientific research on MIS 5 sea level. The discussion is focused on MIS 5e, but records that capture MIS 5d, 5c, 5b, and 5a are also included. We present the data from 71 speleothems (36 sea-level index points and 37 limiting points) in coastal caves located in 10 different locations, and we include the spatial coverage, the samples used, and their accuracy as indicators of sea level, U and Th isotopes used to generate the chronologies, and their scientific relevance to understand past sea-level changes. Furthermore, the paper emphasizes the usefulness of these indicators not only to render information regarding the eustatic sea level, but also for their contribution to refine the glacial isostatic adjustment models and to constrain regional tectonic uplift rates. The standardized sea-level database presented here is the first of its kind derived from speleothems and contains all the information needed to assess paleo relative sea levels and the chronological constraints associated with them. The database is available open-access at https://doi.org/10.5281/zenodo.4313860 (Dumitru et al., 2020). We refer the readers to the official documentation of the WALIS database at https://walis-help.readthedocs.io/en/latest/ (last access: 20 January 2021), where the meaning of each field is explained in detail.

Changes in Organic Matter Deposition Can Impact Benthic Marine Meiofauna in Karst Subterranean Estuaries

Subsurface mixing of seawater and terrestrial-borne meteoric waters on carbonate landscapes creates karst subterranean estuaries, an area of the coastal aquifer with poorly understood carbon cycling, ecosystem functioning, and impact on submarine groundwater discharge. Caves in karst platforms facilitate water and material exchange between the marine and terrestrial environments, and their internal sedimentation patterns document long-term environmental change. Sediment records from a flooded coastal cave in Cozumel Island (Mexico) document decreasing terrestrial organic matter (OM) deposition within the karst subterranean estuary over the last ∼1,000 years, with older sediment likely exported out of the cave by intense storm events. While stable carbon isotopic values (δ13Corgranging from −22.5 to −27.1‰) and C:N ratios (ranging from 9.9 to 18.9) indicate that mangrove and other terrestrial detritus surrounding an inland sinkhole are the primarily sedimentary OM supply, an upcore decrease in bulk OM and enrichment of δ13Corgvalues are observed. These patterns suggest that a reduction in the local mangrove habitat decreased the terrestrial particulate OM input to the cave over time. The benthic foraminiferal community in basal core sediment have higher proportions of infaunal taxa (i.e.,Bolivina) andAmmonia, and assemblages shift to increased miliolids and less infaunal taxa at the core-top sediment. The combined results suggest that a decrease in terrestrial OM through time had a concomitant impact on benthic meiofaunal habitats, potentially by impacting dissolved oxygen availability at the microhabitat scale or resource partitioning by foraminifera. The evidence presented here indicates that landscape and watershed level changes can impact ecosystem functioning within adjacent subterranean estuaries.

Coastal caves on the Interview Island of Andaman Islands, India

By the presence of well-developed terraces on the Interview Island of Middle Andaman, we conducted an exploratory study on the Interview Island of Andaman and Nicobar Islands to understand the development of coastal caves here. During the investigation, we identified seven coastal caves on the island. Morphometric data of these study caves were used for further quantitative analysis by following the area/perimeter (A/P) and entrance width/maximum width (E/M) ratios to classify the cave types. We recognized from the results that the coastal caves could not be easily differentiated as flank margin caves based on A/P and E/M ratios. Nevertheless, based on their morphometry, we could confirm the occurrence of sea caves on the East and West coast of the Interview Island. The present study, as part of the more extensive ongoing research to conserve a cave-dwelling bird, allowed us to report and discuss the occurrence of the coastal caves, and their importance to understanding the speleological significance of the Interview Island.