Underwater Cave Research Articles

Fossil peccaries of Late Pleistocene/Holocene (Cetartiodactyla, Tayassuidae) from underwater caves of Serra da Bodoquena (Mato Grosso do Sul State, Brazil)

New records of Catagonus stenocephalus and Tayassu pecari are reported from the karst of Serra da Bodoquena, located at a south-western portion of Brazil near the border with Paraguay. Skull and lower jaw fragments at different stages of mineralisation were retrieved from two limestone underwater caves, Japonês and Nascente do Formoso, associated with clay and sand deposits with no retrievable stratigraphy. C14 dating of fossil mammals from these caves was attempted, but so far no success was achieved, but the inferred age for the associated paleofauna of these caves is Late Pleistocene and Holocene. The morphology of these fossil peccaries, from the most south-western known population in Brazil, is detailed and paleoecological implications are considered.

Paedomorphic features in extant brachiopods, particularly notably deep-sea forms

Evolutionary fixed physical underdevelopment of mature and reproducing organisms, the paedomorphosis, was considered by I.I. Schmalhausen as a result of natural selection for maximum economy of energy expenses in ontogeny. Deep-sea paedomorphic brachiopod taxa have thin semitransparent shells composed of flattened fibers and simplified (underdeveloped) lophophores similar to that of young specimens of closely related shallow-water species and genera. Paedomorphic features of juvenile underdevelopment up to complete disappearance of the brachial skeleton are characteristic of brachiopods dwelling not only at great depths, but also in tidal pools, shallow-water underwater caves, and bottom sreas under conditions of strong currents. Deep-sea paedomorphosis is also known in marine sponges (Porifera), solitary corals (Scleractinia), sipunculids, priapulids, nudibranchs, and sea spiders (Pycnogonida).

Toward Autonomous Exploration in Confined Underwater Environments

In this field note, we detail the operations and discuss the results of an experiment conducted in the unstructured environment of an underwater cave complex using an autonomous underwater vehicle AUV. For this experiment, the AUV was equipped with two acoustic sonar sensors to simultaneously map the caves' horizontal and vertical surfaces. Although the caves' spatial complexity required AUV guidance by a diver, this field deployment successfully demonstrates a scan-matching algorithm in a simultaneous localization and mapping framework that significantly reduces and bounds the localization error for fully autonomous navigation. These methods are generalizable for AUV exploration in confined underwater environments where surfacing or predeployment of localization equipment is not feasible, and they may provide a useful step toward AUV utilization as a response tool in confined underwater disaster areas.

Late Holocene mangrove development and onset of sedimentation in the Yax Chen cave system (Ox Bel Ha) Yucatan, Mexico: Implications for using cave sediments as a sea-level indicator

Abstract This study examines the relationship between the flooding of cenotes and formation of coastal mangrove with Holocene sea-level rise and the onset of aquatic sedimentation in Yax Chen, a cave system in Quintana Roo on Mexico's Yucatan Peninsula. Sediment depth measurements (n = 180) were collected along 2.7 km of an underwater cave passage and three cores were radiocarbon dated to examine both the extent and timing of sedimentation in the cave. Basal radiocarbon ages (~ 4 Ka) for aquatic sediments in the cave show that Holocene sea-level rise flooded cenotes, creating sunlit open water conditions with associated mangroves on the upper karst surface. These conditions initiated abundant and widespread sedimentation in the cave. Cenote surface area controlled the long-term sediment accumulation in the cave passages through primary productivity in the sunlit open water areas of the cenotes. This primary productivity was enhanced with mangrove formation, which causes funneling of precipitation and nutrient-rich waters into the cenotes from the mangroves. Accumulation histories from the radiocarbon-dated sediment cores (n = 3) were compared with accumulation histories in previously published studies including Actun Ha, Mexico and Green Bay Cave (GBC), Bermuda.

In situUnderwater Tagging of Aquatic Organisms: A Test Using the Cave-Dwelling Olm,Proteus anguinus

In situ ecological studies on obligate cave-dwelling aquatic animals are scarce at best. This is particularly true for capture-mark-recapture (CMR) studies that form the basis of understanding population structure and dynamics. Here, we report on the in situ underwater application of the Visible Implant Elastomer (VIE) tagging system on the olm, Proteus anguinus, an obligate cave-dwelling aquatic amphibian. We tagged seven adult individuals and monitored the population during 31 dive transects during four years. We found that VIE tagging is applicable underwater. Based on our recaptures, the tags were recognisable after four years and the recaptured three individuals exhibited extreme site-fidelity. Our results indicate that CMR studies are feasible in underwater cave ecosystems without even temporarily removing individuals. In situ underwater tagging also holds great potential for studies of other aquatic ecosystems, where removing animals from water, their habitat or territory is problematic for ethical, logistic or scientific reasons.

Preliminary DNA-based diet assessment of a gutless carnivore, the sponge Asbestopluma hypogea

Deep-sea and underwater cave habitats are oligotrophic environments representing strong selective pressures for marine organisms. One family of sponges, Cladorhizidae, consists of very peculiar sponge species that have successfully colonised the deepest oceans as well as caves. They are not filter-feeders as every other Porifera but have evolved to become gutless carnivores. Assessing the diet of such organisms lacking a regular gut appears challenging using classic trophic ecological methods but is rather promising using molecular approaches. We here assessed the in situ diet of the carnivorous sponge Asbestopluma hypogea Vacelet & Boury-Esnault, 1995 by targeting the remaining prey DNA. Using 18S rDNA primers that do not amplify the sponge predator, we were able to amplify prey DNA over a large taxonomic range. DNA belonging to e.g. copepods, polychaetes, nematodes, brittle stars and mysids was detected. Some of these organisms were indeed visually identified as effective prey for the carnivorous sponge A. hypogea and these findings are in accordance with its opportunistic mode of feeding. When combined with stable isotope approach and morphological identification of captured prey, this method can be very useful to understand some of the diet of cladorhizid sponges.

Anthropology. Comment on "Late Pleistocene human skeleton and mtDNA link Paleoamericans and modern Native Americans".

Chatters et al. (Reports, 16 May 2014, p. 750) reported the retrieval of DNA sequences from a 12,000- to 13,000-year-old human tooth discovered in an underwater cave in Mexico's Yucatan peninsula. They propose that this ancient human individual's mitochondrial DNA (mtDNA) belongs to haplogroup D1. However, our analysis of postmortem damage patterns finds no evidence for an ancient origin of these sequences.

Beowulf ’s Poetics of Absorption: Narrative Syntax and the Illusion of Stability in the Fight with Grendel’s Mother

Beowulf ’s Poetics of Absorption: Narrative Syntax and the Illusion of Stability in the Fight with Grendel’s Mother Evelyn Reynolds In Beowulf, the last survivor stands before the barrow in which he has just interred his kin (lines 2236–2246).1 Absorbed in grief, he then speaks his famous lament for his lost people. The poem allows us partly to imagine the survivor and his world as his lament unfolds, but it also bars us from becoming fully affectively engaged with him by positioning him as alone (he has no audience, and he does not address us; we only overhear him) and by setting his elegy in syntactically negative, imagistically sketchy forms (lines 2247–2254). “Heald þū nū, hrūse, nū hæleð ne m(ō)stan, / eorla ǣhte” [Earth, hold now the possessions of earls, what heroes cannot] (lines 2247–2248), the survivor opens, but in this sentence he gives no more precise direct object than “eorla ǣhte” [possessions of earls]. Instead of describing his people’s treasure, he says that “hyt ǣr . . . / gōde begēaton” [good men earlier obtained it] (lines 2248–2249). Beowulf does not allow its audience to picture the treasures or the survivor or his people, and by preventing a full mental picturing, it lessens affective engagement.2 We are thus barred from sympathy with the survivor’s grief at the same time as we hear his expression of grief. The poem focuses the audience’s attention on the survivor, yet denies them their full ability to sympathize with him. This state of imaginative and affective suspension I call the absorption-denial dynamic.3 The absorption-denial dynamic exemplified by the lay of the last survivor characterizes several passages in Beowulf and provides a useful means of understanding how Beowulf ’s formal elements operate on the imaginative and affective states of the poem’s audience.4 As I define it, the absorption-denial dynamic is the way in which a poem immerses its audience while at the same time distancing that audience. We are familiar with the sense of being absorbed in a text—that sense of having our imaginations filled with imagery and emotion. Yet the absorption-denial dynamic makes explicit the paradoxical fact that the artwork also forces its audience [End Page 43] to realize that they are outside its world, ultimately not able to sympathize with or picture its characters fully. One effect of the absorption-denial dynamic is a stilling of time: the audience finds itself suspended between immersion in and separation from the artwork. Often, absorptive pieces represent moments in which something is about to change but has not yet done so—the survivor is about to die from heartbreak; Heorot is about to burn—to enhance the audience’s sense of imaginative or affective suspension with a sense of temporal suspension. In this article, I will focus on a passage in Beowulf that embodies this liminal temporality in a surprising way. This passage is Beowulf’s fight with Grendel’s mother, which runs from line 1399 to line 1569. Depicting Beowulf’s encounter with Grendel’s mother in her underwater cave, the fight scene is an example of an epic set piece. It is an unusual example of an absorptive scene since it is not contemplative or explicitly affective, as is the lay of the last survivor or the poem’s concluding depiction of Beowulf’s funeral pyre. Beowulf and the monster are absorbed in fighting each other; the audience expects a dynamic, quickly moving battle narrative, a narrative that invites complete imaginative immersion in the action. Beowulf’s fight with Grendel’s mother contains syntactic structures that are not present during Beowulf’s fight with Grendel, syntactic structures that might seem aesthetically counterintuitive to a modern audience. Indeed, whereas Beowulf’s fight with Grendel often receives scholarly attention because the poet renders the fight in gripping synesthetic detail, his fight with Grendel’s mother has seldom been discussed in aesthetic terms.5 However, the poem’s linguistic structures here actually slow the narrative’s pace and prevent audience immersion. A reexamination of Beowulf ’s formal elements in light of the way they position the poem’s audience, particularly...

Chemosynthetic ectosymbiosis reported in the predatory anchialine cave endemic, Xibalbanus tulumensis (Yager, 1987) (Remipedia)

Mutualisms between chemosynthetic microbes and invertebrates form the basis of foodwebs in dark, extreme habitats (hydrothermal vents, cold seeps) and have likely facilitated the invasion of extreme underwater caves, as well. Anchialine caves often include distinct water layers of varying concentrations of dissolved oxygen and sulfide and provide an ideal system for the discovery of chemosynthetically based systems and novel symbioses. These caves can be harsh environments for eukaryotes, but they contain gradients favorable for chemosynthetic symbiotic microbes. Here, we provide evidence of chemosynthetic ectosymbiosis in a member of the Remipedia, Xibalbanus tulumensis (Yager, 1987), through electron microscopy and stable isotope analysis. Remipedes are considered to be top predators due to anecdotal observations of feeding in the lab and field, and description of venomous apparati; but they may supplement their diet with microbes. This finding sheds light on opportunistic feeding behaviors that may have evolved to combat resource-limited environments, such as dark, underwater caves.

1A1-G08 3Dモデリングを目指した水中洞窟探査用自律型水中ロボットの開発(水中ロボット・メカトロニクス(1))

1A1-G08 3Dモデリングを目指した水中洞窟探査用自律型水中ロボットの開発(水中ロボット・メカトロニクス(1))

Late Holocene sedimentation and hydrologic development in a shallow coastal sinkhole on Great Abaco Island, The Bahamas

It remains poorly understood how sea level drives environmental change and hydrographic development in coastal karst basins (underwater caves, sinkholes, blueholes, etc.) over millennial timescales. It was previously hypothesized that coastal karst basins (CKBs) transition from vadose, to littoral, then anchialine, and finally submarine environments as sea-level rise inundates coastal karst landscapes, but the initial flooding event of CKBs remains challenging to sample. Runway Sinkhole hosts a modern anchialine ecosystem located ∼225 m from Great Abaco Island coastline in The Bahamas, and its shallow water depth (∼1.8 mbsl) permits an investigation into the early environmental evolution and hydrographic development in a CKBs after inundation by sea-level rise. Four sediment cores were collected from Runway Sinkhole, and late Holocene environmental change was reconstructed with benthic foraminiferal paleoecology, organic matter geochemistry (OM%, δ13Corg, and C:N), X-radiography, and radiocarbon dating. Despite some uncertainties associated with the chronology, it appears that Holocene sea-level rise initially flooded Runway Sinkhole and created a littoral environment at least by ∼3.9 ka, whereafter a detrital peat deposit accumulated in the sinkhole. This detrital peat had a high organic matter content (mean 88%), a δ13Corg value indicative of organic matter derived from C3 plants including mangroves (−28‰), and an unknown calcareous microfossil suggestive of a non-marine habitat in the sinkhole. A shift to carbonate sand deposition, organic matter with more marine-influenced δ13Corg values (−23‰), and expansion of euryhaline (Bolivina striatula, Elphidium poeyanum, and Triloculina bermudezi) and anchialine (Physalidia simplex and Conicospirillina exleyi) benthic foraminifera at ∼1.2 ka marks the onset of modern anchialine environmental conditions at the sediment–water interface (∼1.8 mbsl). These results suggest that relative sea-level rise in the Bahamas forced environmental change in Runway sinkhole at ∼1.2 ka, and indicate that peat deposits in coastal sinkholes must be verified as in-situ before being utilized as sea-level indicators.

SPELEOTHERAPY DEVELOPMENT IN ROMANIA ON THE WORLD CONTEXT AND PERSPECTIVES FOR USE OF SOME SALT MINES AND KARST CAVES FOR SPELEOTHERAPEUTIC AND BALNEOCLIMATIC TOURISM PURPOSES

Speleotherapy (ST) is a relatively new method of complementary medicine, although, as is well known ancient tribes appreciated isolation in underwater caves, salt or karst caves, or possessing various ores and was officially recognized in the years 1950-1960 in Germany (K.Spannagel, 1961) and Poland (M. Skulimowski, 1965). Professor Mieczyslaw Skulimowski has granted of speleotherapy in Wieliczka Salt Mine, the name of subterraneotherapy, soon to be also called the Skulimowski method. Number of speleotherapeutic centers and speleotherapy symposiums has increased considerably (H.Trimmel, 1994). Speleotherapy in the underground now is an effective therapeutic method for the treatment of obstructive respiratory tract diseases, especially of patients with bronchial asthma (BA), the upward and effective practice in Central and Eastern Europe, but also in the West: Austria, Czech Republic, Germany, Poland, Russia, Slovakia, Ukraine, Belarus, Hungary etc. In the World, known about 60 underground salt and other mines, carst caves used for ST or are under experimental study to evaluate the possibility to be used for speleotherapy, including: Germany, Hungary, Czech Republic, Slovakia, Austria, Slovenia, Ukraine, Romania and other countries. In salt mines with 9-24 °C temperature operating 15 speleotherapy centers, 34 in karst caves with 9-18 °C, and 4 centers in thermal caves with temperatures higher than 24 C (Iu. Simionca et al., 2005). In the last twenty years ST occupies an important place in salt mines mines and carst caves with different parameters: Wieliczka, Poland; Solotvino / Slatina, Ukraine; Bad Bleiberg, Austria; Klutert Hohl, Germany; Zlate Hory and Cisarska Cave, Czech Republic; Bystrianska Jaskyna, Slovakia; Tapolca Seehohle, Hungary; Unirea Salt Mine Slanic Prahova, Romania and will occupy a significant place the Turda Salt Mine, Cacica, Tg. Ocna, and Praid salt mines from Romania (Iu.Simionca et al., 2006, 2009). Is of scientific and practical interest formation in world of new directions in the treatment of the most common and severe allergic diseases asthma, namely the use of underground environmental factors in order to reduce human outcome of the action of environmental allergy. In this context, the use of salt mines and caves as natural therapeutic factors also known as speleotherapy, is a special scientific interest, a perspective direction in the areas of health and environment. Today speleotherapy is known as the therapy of patients with various diseases in the underground salt mines and caves possessing natural therapeutic factors (Iu.Simionca et al., 1998, 2005, 2006, 2009). Analysis of the speleotherapy domain status allowed to establish that use saline or cave underground natural environmental factors which own curative properties for prevention, treatment and rehabilitation of patients with certain diseases, often

The Cuban crocodile (Crocodylus rhombifer) from late Quaternary fossil deposits in the Bahamas and Cayman Islands

Late Quaternary fossil deposits from The Bahamas, Cayman Islands, and Cuba contain fossils of the Cuban crocodile Crocodylus rhombifer. This species survives today only in Cuba and Isla de la Juventud (formerly Isla de Pinos); the populations in The Bahamas and Cayman Islands are locally extinct. Large fossil samples, including skulls, are known from underwater caves (blue holes) on Abaco in the northern Bahamas and organic peat deposits on Grand Cayman. Diagnostic cranial characters shared by the fossil crocodile skulls from Abaco and Grand Cayman and recent skulls of C. rhombifer from Cuba are: short, broad, and deep rostrum; prominent orbit; concave interorbital region and cranial roof; strong ridge on internal margin of the orbit and lateral margin of the cranial table; large, rounded protuberance on the posterolateral corner of the squamosal; premaxillary-maxillary suture on the palate transverse at the level of the first maxillary tooth; and 13 teeth in the maxilla. Using a ratio derived from living crocodylians of head length (premaxilla to parietal) to total length of about 1:7.2, approximate total lengths for fossil specimens of C. rhombifer from Abaco range from 1.3–2.3 m (mean 1.9 m) and Grand Cayman from 1.6–2.0 m (mean 1.7 m). Quaternary crocodylian remains are known from many other islands in The Bahamas, including Acklins, Crooked Island, Eleuthera, Grand Bahama, Mayaguana, New Providence, and San Salvador; however, most of these fossils are not complete enough for a species identification. Shells of an extinct species of the land tortoise Chelonoidis from Abaco and Mayaguana with crocodylian bite marks, jaws and teeth of capromyid rodents from Grand Cayman that appear to have been digested by a crocodylian, and data from carbon (13C/12C) isotopes derived from crocodile bones, as well as the lack of large freshwater vertebrates, suggest that C. rhombifer in The Bahamas and Cayman Island had a diet primarily consisting of terrestrial vertebrates. Evidence from stomach contents and behavioral ecology of extant Cuban crocodiles from Cuba further supports the terrestrial feeding habits of C. rhombifer. Radiocarbon (14C) dates on crocodile postcranial bones from Sawmill Sink and Dan’s Cave on Abaco range from 2,780–3,680 years Before Present (BP). Radiocarbon dates on peat associated with fossils of C. rhombifer from the Crocodile Canal site on Grand Cayman range from 375–860 years BP. These dates confirm that Cuban crocodiles survived into the late Holocene on Abaco and into the historic period on Grand Cayman. Evidence from a variety of sources, including radiocarbon dates, fossil and archaeological sites, and historical records confirms that the local extinction of crocodiles in The Bahamas and Cayman Islands occurred within the past 500 years, probably resulting from overhunting by humans. Fossils of C. rhombifer on Grand Cayman and Abaco, and probably throughout The Bahamas, verify that the Cuban crocodile was considerably more widespread in the West Indies during the Late Quaternary.

Heightened hurricane activity on the Little Bahama Bank from 1350 to 1650 AD

Deciphering how the climate system has controlled North Atlantic tropical cyclone activity through the Holocene will require a larger observational network of prehistoric hurricane activity. Problematically, the tropical North Atlantic is dominated by carbonate landscapes that typically preserve poorer quality coastal sediment records in comparison to their temperate-region counterparts (e.g., sedimentation continuity and rate). Coastal karst basins (CKBs), such as sinkholes, blueholes, and underwater caves, are widely distributed on carbonate platforms and contain overlooked sedimentary records. Here we present a millennium of hurricane deposits on the Little Bahama Bank archived in a 165cm core that was extracted from 69m below sea level in a bluehole on Great Abaco Island, The Bahamas. The coarse-grained overwash deposits associated with both hurricanes Jeanne (2004) and Floyd (1999) were identified using radioisotopes (137Cs, 14C, 210Pb), and indicate that the bluehole is sensitive to hurricane-induced sedimentation. Over the last millennium, the Little Bahama Bank experienced heightened hurricane activity from 1350 to 1650 AD. The simplest explanation for this active interval is that favorable climate conditions (El Niño, West African Monsoon, and sea surface temperatures) encouraged North Atlantic hurricane activity at that time. However, asynchronous hurricane activity at similar latitudes in the North Atlantic and Gulf of Mexico suggest that regional oceanography has modulated or amplified regional hurricane activity over the last millennium.

Life in the dark: metagenomic evidence that a microbial slime community is driven by inorganic nitrogen metabolism

Beneath Australia's large, dry Nullarbor Plain lies an extensive underwater cave system, where dense microbial communities known as 'slime curtains' are found. These communities exist in isolation from photosynthetically derived carbon and are presumed to be chemoautotrophic. Earlier work found high levels of nitrite and nitrate in the cave waters and a high relative abundance of Nitrospirae in bacterial 16S rRNA clone libraries. This suggested that these communities may be supported by nitrite oxidation, however, details of the inorganic nitrogen cycling in these communities remained unclear. Here we report analysis of 16S rRNA amplicon and metagenomic sequence data from the Weebubbie cave slime curtain community. The microbial community is comprised of a diverse assortment of bacterial and archaeal genera, including an abundant population of Thaumarchaeota. Sufficient thaumarchaeotal sequence was recovered to enable a partial genome sequence to be assembled, which showed considerable synteny with the corresponding regions in the genome of the autotrophic ammonia oxidiser Nitrosopumilus maritimus SCM1. This partial genome sequence, contained regions with high sequence identity to the ammonia mono-oxygenase operon and carbon fixing 3-hydroxypropionate/4-hydroxybutyrate cycle genes of N. maritimus SCM1. Additionally, the community, as a whole, included genes encoding key enzymes for inorganic nitrogen transformations, including nitrification and denitrification. We propose that the Weebubbie slime curtain community represents a distinctive microbial ecosystem, in which primary productivity is due to the combined activity of archaeal ammonia-oxidisers and bacterial nitrite oxidisers.

Grey seal Halichoerus grypus in the Black Sea: the first case of long-term survival of an exotic pinniped

A grey seal (Halichoerus grypus), representative of the North Atlantic species, has been recorded in the north-east Black Sea. It is the first documented case of successful long-term survival of an exotic pinniped. We have been receiving data about regular sightings of the seal identified as the observed individual since 2001. It is a 160–170 cm long adult female. The seal used an underwater cave as a shelter. The most likely way of introduction of the grey seal to the Black Sea is escape from captivity. According to available data (body size and moulting seasonality), we tentatively identify it as a representative of the Baltic subspecies. The biotope requirements of the grey seal and monk seal are similar: both species use coastal karst caves and grottos. In addition, the seal's presence in this region is a marker of the lack of anthropogenic disturbance. Thus, the survival of a seal in this region indicates the possibility of successful re-colonization of the Black Sea by monk seals.

Floristic macroalgal diversity in selected submarine caves located within two marine protected areas off Lampedusa Island and Sicily (Italy)

Abstract We investigated phytobenthos in submerged marine caves. Underwater caves have rarely been examined for floristic composition. The study was carried out in two Mediterranean marine protected areas (MPAs) [Plemmirio (Maddalena Peninsula, Syracuse, Ionian Sea) and Pelagean Islands (Straits of Sicily)] and the caves were chosen on the basis of their geomorphology, exposure, and bathymetry. From our comparative study of cave floras, we demonstrated that the macroalgal flora of each cave is influenced by the floristic composition of the adjacent area that is a natural source of recruits and by the light environment. Caves that are “visited” (i.e., those situated on one of the underwater routes for scuba divers visiting the MPAs) had floristic richnesses higher than those of “scarcely” or “not visited” ones (i.e., not on tourist routed). This is likely because the visited caves, due to their large entrance and shallow location, have good lighting that favors high macroalgal biodiversity.

Sea level controls sedimentation and environments in coastal caves and sinkholes

Quaternary climate and sea-level research in coastal karst basins (caves, cenotes, sinkholes, blueholes, etc.) generally focuses on analyzing isotopes in speleothems, or associating cave elevations prior sea-level highstands. The sediments in coastal karst basins represent an overlooked source of climate and sea-level information in the coastal zone, but to accurately interpret these sediments first requires an understanding of the forcing mechanisms that emplace them. In this study, we hypothesize that coastal karst basins transition through vadose, littoral, anchialine, and finally into submarine environments during sea-level rise because groundwater and sea level oscillate in near synchrony in the coastal zone, causing each environment to deposit a unique sedimentary facies. To test this hypothesis, the stratigraphy in twelve sediment cores from a Bermudian underwater cave (Green Bay Cave) was investigated and temporally constrained with twenty radiocarbon dates. The results indicate that we recovered the first succession spanning the entire Holocene from an underwater cave (~ 13 ka to present). The sediments were characterized with X-radiography, fossil remains, bulk organic matter, organic geochemistry (δ 13C org, C:N), and grain size analysis. Four distinct facies represent the four depositional environments: (i) vadose facies (> 7.7 ka, calcite rafts lithofacies), (ii) littoral facies (7.7 to 7.3 ka: calcite rafts and mud lithofacies), (iii) anchialine facies (7.3 to 1.6 ka: slackwater and diamict lithofacies), and (iv) submarine facies (< 1.6 ka: carbonate mud and shell hash lithofacies). The onset and duration of these sedimentary depositional environments are closely linked to Holocene sea-level rise in Bermuda, indicating that sea level controls environmental development in coastal karst basins. Finally, we present a conceptual model for interpreting the sediments and environments in coastal karst basins as a result of sea-level change.

First skull of Antillothrix bernensis, an extinct relict monkey from the Dominican Republic.

The nearly pristine remains of Antillothrix bernensis, a capuchin-sized (Cebus) extinct platyrrhine from the Dominican Republic, have been found submerged in an underwater cave. This represents the first specimen of an extinct Caribbean primate with diagnostic craniodental and skeletal parts in association, only the second example of a skull from the region, and one of the most complete specimens of a fossil platyrrhine cranium yet discovered. Cranially, it closely resembles living cebines but is more conservative. Dentally, it is less bunodont and more primitive than Cebus, with crowns resembling Saimiri (squirrel monkeys) and one of the oldest definitive cebines, the late Early Miocene Killikaike blakei from Argentina. The tricuspid second molar also resembles the enigmatic marmosets and tamarins, whose origins continue to present a major gap in knowledge of primate evolution. While the femur is oddly short and stout, the ulna, though more robust, compares well with Cebus. As a member of the cebid clade, Antillothrix demonstrates that insular Caribbean monkeys are not monophyletically related and may not be the product of a single colonizing event. Antillothrix bernensis is an intriguing mosaic whose primitive characters are consistent with an early origin, possibly antedating the assembly of the modern primate fauna in greater Amazonia during the La Venta horizon. While most Greater Antillean primate specimens are quite young geologically, this vanished radiation, known from Cuba (Paralouatta) and Jamaica (Xenothrix) as well as Hispaniola, appears to be composed of long-lived lineages like several other mainland clades.

Linkages between Holocene paleoclimate and paleohydrogeology preserved in a Yucatan underwater cave

Three sediment cores spanning the last 4200 years from Aktun Ha Cave on the Yucatan Peninsula (Mexico) demonstrate that underwater caves can document changes to regional hydrogeology and climate. Benthic microfossils (testate amoebae, foraminifera), organic matter geochemistry (δ 13C, δ 15N, C/N), and particle size distributions were analyzed. However, microfossil paleoecology proved the most useful for indicating three salinity phases in the Aktun Ha sediment cores. Phase 1 (>4300 yr BP) contains predominantly foraminifera ( Physalidia simplex, 78%) that indicate the meteoric lens flooding the cave was initially brackish (salinity >3.5 g L −1). Phase 2 (2800–4300 Cal yr BP) has both freshwater testate amoebae ( Centropyxis spp. 40%) and P. simplex (42%), which indicates a slight freshening of the meteoric lens to 1.5–2 g L −1. Phase 3 (<2800 yr BP) is demarcated by an increase in testate amoebae abundance (90%) and diversity, including the colonization of Lagenodifflugia vas and Difflugia oblonga, with a reduction in P. simplex (10%). This last faunal shift represents the initiation of modern freshwater conditions in the cave (1.5 g L −1). This final freshening is synchronous with a significant reduction in the C/N ratio (e.g., Core 2: ∼27 to 19), which suggests an expansion of primary productivity in the adjacent cenote. The δ 15N values ranged from 1.5 to 3.5‰ with observed cycles likely from intervals of increased terrestrial OM input into the cave during high rainfall events (e.g., hurricanes). The observed paleoenvironmental shifts in the cave correlate well with regional precipitation patterns, aquifer recharge, and storm activity caused by southward migration of the Intertropical Convergence Zone. Therefore, regional climate change impacted eastern Yucatan groundwater during the mid to late Holocene. However, decelerating Holocene sea-level rise and aquifer occlusion are likely contributing factors. These results demonstrate that underwater cave sediments and microfossils can be useful proxies for aquifer evolution and climate change.