Re-discovery of a "living fossil" coccolithophore from the coastal waters of Japan and Croatia

The extant coccolithophore Tergestiella adriatica Kamptner, which had not been reported since its original description in 1940, was recently re-discovered in coastal-nearshore waters at Tomari, Tottori (Japan) and offshore Rovinj (Croatia). Morphological analysis shows that extant Tergestiella and the Mesozoic genus Cyclagelosphaera (Watznaueriaceae), thought to have been extinct since the early Eocene (~. 54. Ma), are virtually identical. Molecular phylogenetic study supports the inference that T. adriatica is a direct descendent of Cyclagelosphaera. It is therefore a remarkable example of a living fossil. Our documentation of patchy coastal distribution in living T. adriatica and records of rare occurrences of fossil Cyclagelosphaera in Oligocene-Miocene shallow water sediments. , from the New Jersey shelf, suggest that Tergestiella/. Cyclagelosphaera was restricted to nearshore environments during much of the Cenozoic. This restricted ecology explains the lack of fossil Tergestiella/. Cyclagelosphaera recorded in open ocean sediments deposited during the last 54. myr.Floristic study of coccolithophores in the coastal and offshore waters of Tomari over a six-year period, show that T. adriatica occurs synchronously with the unusual neritic species, Braarudosphaera bigelowii, in mid-June. The environmental factors that induce the co-occurrence of these two taxa are uncertain, and T. adriatica did not co-occur with B. bigelowii at any other sites

Data report: composite depth scale and splice revision for IODP Site U1488 (Expedition 363 Western Pacific Warm Pool) using XRF core scanning data and core images

The Western Pacific Warm Pool (WPWP) is a major source of heat and moisture to the atmosphere. Small perturbations in WPWP sea-surface temperatures greatly influence local Hadley and Walker cells, thereby affecting global atmospheric circulation patterns. International Ocean Discovery Program (IODP) Expedition 363 sought to document the regional expression and driving mechanisms of WPWP climate variability during the Neogene on millennial, orbital, and geological timescales. Located in the heart of the WPWP, IODP Site U1488 (02°02.59ʹN, 141°45.29ʹE) was drilled in 2604 m water depth on the southern part of the Eauripik Rise in the Caroline Basin. At Site U1488, a continuous shipboard composite stratigraphic section from 0 to ~331 m core composite depth below seafloor (CCSF) was compiled using high-resolution shipboard physical property data from three holes. This section comprises upper Miocene to recent foraminifer-rich nannofossil ooze and foraminifer-nannofossil ooze, making Site U1488 ideally suited to reconstruct the paleoceanographic history of the central WPWP region. However, the high carbonate content (>90% below ~180 m CCSF) of Site U1488 sediments means that the physical property data sets commonly used for splice construction (gamma ray attenuation bulk density, magnetic susceptibility, and natural gamma radiation) were too low amplitude to provide robust constraints on splice tie points below 120 m CCSF. As a result, P-wave data, which are relatively untested as a correlation tool, became critical for correlating between holes. Here, we verify and extend the Site U1488 shipboard composite splice using high-resolution (2 cm) X-ray fluorescence Ba/Sr core scanning data combined with composite linescan images. Overall, using these data at Site U1488 resulted in revised core offsets that differ by up to 0.84 m relative to the shipboard core offsets and a composite depth scale down to 329.33 m revised CCSF. The revised splice will allow optimization of postexpedition research and ensure that high-resolution studies of Site U1488 are conducted on a continuous stratigraphic section

A large West Antarctic Ice Sheet explains early Neogene sea-level amplitude

Early to Middle Miocene sea-level oscillations of approximately 40-60 m estimated from far-field records1-3 are interpreted to reflect the loss of virtually all East Antarctic ice during peak warmth2. This contrasts with ice-sheet model experiments suggesting most terrestrial ice in East Antarctica was retained even during the warmest intervals of the Middle Miocene4,5. Data and model outputs can be reconciled if a large West Antarctic Ice Sheet (WAIS) existed and expanded across most of the outer continental shelf during the Early Miocene, accounting for maximum ice-sheet volumes. Here we provide the earliest geological evidence proving large WAIS expansions occurred during the Early Miocene (~17.72-17.40 Ma). Geochemical and petrographic data show glacimarine sediments recovered at International Ocean Discovery Program (IODP) Site U1521 in the central Ross Sea derive from West Antarctica, requiring the presence of a WAIS covering most of the Ross Sea continental shelf. Seismic, lithological and palynological data reveal the intermittent proximity of grounded ice to Site U1521. The erosion rate calculated from this sediment package greatly exceeds the long-term mean, implying rapid erosion of West Antarctica. This interval therefore captures a key step in the genesis of a marine-based WAIS and a tipping point in Antarctic ice-sheet evolution

Predicting predatory impact of juvenile invasive lionfish (Pterois volitans) on a crustacean prey using functional response analysis: effects of temperature, habitat complexity and light regimes

The ecological implications of biotic interactions, such as predator-prey relationships, are often context-dependent. Comparative functional responses analysis can be used under different abiotic contexts to improve understanding and prediction of the ecological impact of invasive species. Pterois volitans (Lionfish) [Linnaeus 1758] is an established invasive species in the Caribbean and Gulf of Mexico, with a more recent invasion into the Mediterranean. Lionfish are generalist predators that impact a wide range of commercial and non-commercial species. Functional response analysis was employed to quantify interaction strength between lionfish and a generic prey species, the shrimp (Paleomonetes varians) [Leach 1814], under the contexts of differing temperature, habitat complexity and light wavelength. Lionfish have prey population destabilising Type II functional responses under all contexts examined. Significantly more prey were consumed at 26 °C than at 22 °C. Habitat complexity did not significantly alter the functional response parameters. Significantly more prey were consumed under white light and blue light than under red light. Attack rate was significantly higher under white light than under blue or red light. Light wavelength did not significantly change handling times. The impacts on prey populations through feeding rates may increase with concomitant temperature increase. As attack rates are very high at low habitat complexity this may elucidate the cause of high impact upon degraded reef ecosystems with low-density prey populations, although there was little protection conferred through habitat complexity. Only red light (i.e. dark) afforded any reduction in predation pressure. Management initiatives should account for these environmental factors when planning mitigation and prevention strategies

Temperature-dependent frictional properties of heterogeneous Hikurangi Subduction Zone input sediments, ODP Site 1124

The Hikurangi Subduction Zone (HSZ), New Zealand, accommodates westward subduction of the Pacific Plate. Where imaged seismically, the shallow HSZ décollement (<10–15 km depth) occurs within or along the upper contact of Late Cretaceous-Paleogene (70–32 million-year-old) sediments. The frictional properties of Paleogene sediments recovered from Ocean Drilling Program Leg 181, Site 1124 were measured at 60 MPa effective normal stress and varying sliding velocities (V = 0.3–30 µm/s) and temperatures (T = 25–225 °C). Velocity-stepping experiments were conducted at temperatures of 25 °C, 75 °C, 150 °C, and 225 °C to determine the friction rate parameter (a–b). Paleocene and Oligocene clay-bearing nannofossil chalks (μ = 0.45–0.61) and a middle Eocene clayey nannofossil chalk (μ = 0.35–0.51) are frictionally stronger than smectite-bearing Eocene clays (μ = 0.16–0.31). With increasing temperature, chalks show rate-strengthening to rate-weakening frictional stability trends; clays show rate-weakening and rate-neutral to rate-strengthening frictional stability trends. The results obtained from Site 1124 sediments indicate that: (1) fault-zone weakness may not require pore-fluid overpressures; (2) clays and chalks can host frictional instabilities; and (3) heterogeneous frictional properties can promote variable slip behaviour