Origin of double‐tower raft cones in hypogenic caves

In the present paper, we describe the genetic mechanism that causes the precipitation of raft cones in caves. These speleothems usually form in a hydrothermal and epiphreatic environment where dripwater, dripping repeatedly over the same spot, sinks calcite rafts that were floating on the water surface of a cave pool. In particular, the paper describes a new variety of raft cones that were recently discovered in the Paradise Chamber of the Sima de la Higuera Cave (Murcia, south‐eastern Spain) based on their morphological and morphometric characteristics. These speleothems, dubbed ‘double‐tower cones’, have a notch in the middle and look like two cones, one superimposed over the other. The genetic mechanism that gave rise to the double‐tower cones must include an intermediate stage of rapid calcite raft precipitation, caused by a drop in the water table and by changes in cave ventilation leading to greater carbon dioxide (CO₂) degassing and evaporation over the surface of the thermal lake where these speleothems formed. Calcite rafts were deposited in Paradise Chamber, completely covering many of the cones. Later, conditions for slower calcite raft precipitation were restored and some of the cones continued to grow at the same points. When the water table finally fell below the level of Paradise Chamber, the tower cones became exposed, as the incongruent deposits of calcite rafts were dissolved and mobilized to lower cave levels. Copyright © 2013 John Wiley & Sons, Ltd.     

Late Holocene record of environmental changes,cyclones and tsunamis in a coastal lake,Mangaia, Cook Islands

A 4.3 m‐long peat sequence from the shore of Lake Tiriara, Mangaia, Cook Islands, was analyzed using an ITRAX core scanner equipped with a magnetic susceptibility meter. Variations in the elemental profiles, providing insights into long‐ and short‐term environmental changes over the last 3500 years, are supported by grain size data and diatom assemblages. The scattering ratio (Mo Inc/Mo Coh) was evaluated and found to represent a good proxy for organic matter in peat. X‐Ray Fluorescence (XRF) data were processed by principal component analysis that confirmed the distinction of biogenic and detrital phases, organic matter and elements of marine origin. The record preserved in the peat sequence includes a peatland infilling stage followed by alternating drier and wetter periods. A notable steady increase in clay associated with high counts of detrital elements from 2000–1700 cal yr BP is attributed to increased erosion, which is most probably linked with human colonization and/or more intense chemical weathering linked with a wetter climate. Freshwater gastropods (Melanoides sp.), which were possibly introduced by humans, or are native, occupied the wetland during a period of lower water level about 1000–1100 cal yr BP. Short‐term changes in the elemental profiles are often linked with slight coarsening of the inorganic fraction that is, however, only revealed after grain size analysis. Peaks in marine indicators (Br, Cl, S, and/or Ca) associated with marine‐dominated diatom assemblages most probably represent marine incursions through the underground tunnel in the makatea, a fossilized, uplifted coral limestone rim. While none of the marine event units present characteristics typical of cyclone or tsunami deposits, the concurrent or absent peak of detrital elements (Fe, Si, Rb, Ti, K) attributed to increased erosion of the volcanic cone associated with a cyclone is used to distinguish both types of events, as also suggested by principal component analysis.     

Determination of the 3D structure of an earthflow by geophysical methods: The case of Super Sauze, in the French southern Alps

In order to evaluate the risk associated by an earthflow to abruptly evolve into a torrential flow, the knowledge of its internal structure is necessary. Geotechnical methods are important to reach this goal. However, because of the rough topography associated with earthflows, their surface heterogeneities, and the spatial variations of the thickness of the potentially moving mass, non-intrusive geophysical methods offer a very useful tool that complements traditional geotechnical methods. We report the results of a comprehensive study covering a 150 m by 200 m area of the Super Sauze earthflow. This earthflow developed in black marls in the southern French Alps. Shallow electrical conductivity investigations, derived using low frequency domain electromagnetics, maps hidden gullies and crests and lateral variations of the clay and the water content within the first 5 m below the ground surface. Electrical resistivity tomography allows to extrapolate this information down to 10 m below the ground surface along selected transects. The vertical structure of the earthflow, down to the substratum, is defined precisely thanks to joint inversion of DC and TDEM vertical soundings along one profile: the flowing upper layer and the position of the substratum are clearly evidenced. Combining this geophysical datasets with geotechnical tests and drill holes, we provide an estimate of both the location and the volume of the potentially most dangerous areas of the earthflow.     

Responses of benthic macrofauna and biogeochemical fluxes to various levels of mussel biodeposition: An in situ “benthocosm” experiment

An in situ experiment was done to evaluate the dose-dependent response of mussel biodeposition on benthic communities and biogeochemical fluxes. Natural benthic communities were exposed to 7 different levels of mussel biodeposition (equivalent to that produced by 0-764 mussels m⁻²) over 50 days. Benthic communities responded as predicted from the Pearson, T.H., Rosenberg, R., 1978. Macrobenthic succession in relation to organic enrichment and pollution of the marine environment. Oceanogr. Mar. Biol. Annu. Rev. 16, 229-311 model of organic enrichment. Total abundance and species richness decreased with increasing biodeposition. The abundance and biomass of opportunistic species (Capitella spp.) increased in the mesocosms subject to the greatest biodeposition. Sensitive species Tellina agilis and Pherusa plumosa tended to decrease in abundance and biomass with increasing biodeposition. The biotic index M-AMBI responded clearly to increased biodeposition and may be a useful tool for assessing the effect of mussel biodeposition on the benthic environment. These results are important for the construction of predictive models for determining environmental carrying capacity for bivalve aquaculture.     

Influence of an oxygen minimum zone and macroalgal enrichment on benthic megafaunal community composition in a NE Pacific submarine canyon

Megafaunal diversity in the deep sea shows a parabolic pattern with depth. It can be affected by factors such as low oxygen concentration, which suppresses diversity, or the presence of submarine canyons, which enhances it. Barkley Canyon, located off the west coast of British Columbia, Canada, is a submarine canyon that extends from the continental margin (200 m) into the deep ocean (2,000 m). This canyon receives drift kelp from shoreline kelp forests and contains an oxygen minimum zone (OMZ) at 500 to 1,500 m depth. Our study investigated the abundance and diversity of epibenthic megafauna over a range of depths (200–2,000 m) and oxygen concentrations (0.5–5.0 ml/L) within Barkley Canyon, as well as changes in abundance near detrital kelp. Video was collected using the remotely operated vehicle ROPOS along seven 1‐km cross‐canyon (i.e., across the axis of the canyon) transects and three 40‐m perpendicular cross‐transects over kelp. Taxonomic groups were associated with depth, temperature, and the presence of pebbles. The OMZ restricted pennatulids, and edge effects along OMZ boundaries were observed for ophiuroids. The geomorphology of the sea floor affected the distribution of taxa across the canyon, with Porifera mainly found along the walls and Echinoidea within the canyon axis. Expected richness exhibited a bimodal pattern, peaking at 300 and 2,000 m, possibly due to the combined effect of the OMZ and the submarine canyon. Echinoidea aggregated near drift kelp at 200 and 300 m. We found that faunal communities in Barkley Canyon were influenced by several confounded factors including depth, oxygen and substrate. Understanding faunal patterns is paramount with increased exploitation and a changing climate.     

Nocturnal CO2 exchange over a tall forest canopy associated with intermittent low-level jet activity

Summary Nocturnal eddy-covariance carbon dioxide fluxes have uncertainties arising from non-stationary atmospheric processes. Low-level jets (LLJ) are one of the prominent nocturnal boundary-layer phenomena observed over non-mountainous terrain, and are capable of generating shear and turbulence close to the ground. The influence of intermittent LLJ activity on nocturnal carbon dioxide exchange measurements is investigated using wind profile observations and eddy-covariance flux measurements over a tall forest canopy. Results suggest that the buildup and venting of CO₂ are closely associated with LLJ activity during the night. Of significance in quantifying nocturnal fluxes, this paper demonstrates how low-level jet activity introduces sporadic coupling between the canopy and the atmosphere.     

The macrozoobenthos of the Karavasta lagoon system (Albania): local assemblages and geographical comparisons

The macrozoobenthic assemblage from the Karavasta lagoon system, the main wetland of Albania, was studied on soft bottoms and artificial hard substrates. Three different communities were identified: the typical ‘brackish‐water community’, an ‘outlet community’ dominated by filter‐feeders, and a typical ‘marine community’, inhabiting fine sandy bottoms, where polychaetes are dominant, together with a few species of tunicates and bivalves, which colonize hard substrates. The occurrence of build‐ups of the bryozoan Conopeum seurati, settled on the upper portion of long submerged wooden poles, was the main feature of faunistic interest. The faunistic affinity between the zoobenthic assemblage recorded in the hyperhaline lagoon of Karavasta and the assemblages from two Italian lagoons, the brackish Lake of Lesina and the euhaline Lake of Fogliano, was considered according to the different hydrological conditions and the geographical location. Hydrological confinement and salinity were likely to be the leading factors influencing the benthic community composition in the Karavasta wetland area. Therefore, on a vaster spatial scale, the isolation and geographical proximity of the ecosystems and colonizing ability and dispersal changes of the species appear to be the main factors liable to produce faunal variations.     

Quantifying the local influence at a tall tower site in nocturnal conditions

The influence of the local terrestrial environment on nocturnal atmospheric CO₂ measurements at a 329-m television transmitter tower (and a component of a CO₂ monitoring network) was estimated with a tracer release experiment and a subsequent simulation of the releases. This was done to characterize the vertical transport of emissions from the surface to the uppermost tower level and how it is affected by atmospheric stability. The tracer release experiment was conducted over two nights in May of 2009 near the Department of Energy’s Savannah River Site (SRS) in South Carolina. Tracer was released on two contrasting nights—slightly stable and moderately stable—from several upwind surface locations. Measurements at the 329-m level on both nights indicate that tracer was able to mix vertically within a relatively short (～24 km) distance, implying that nocturnal stable conditions do not necessarily prevent vertical dispersion in the boundary layer and that CO₂ measurements at the tower are at least partly influenced by nearby emissions. A simulation of the tracer release is used to calculate the tower footprint on the two nights to estimate the degree to which the local domain affects the tower readings. The effect of the nocturnal boundary layer on the area sampled by the tower can be seen clearly, as the footprints were affected by changes in stability. The contribution of local sources to the measurements at the tower was minimal, however, suggesting that nocturnal concentrations at upper levels are contributed mostly by regional sources.     

Fractal properties of temperature fluctuations in the convective surface layer

Temperature fluctuations in a convective surface layer were investigated. Box counting analysis was performed to investigate fractal properties of surfaces of constant temperature and was performed on sets of points obtained by setting thresholds on detrended records. Results indicate that surfaces of constant temperature have fractal properties for thresholds far from the mean. Estimated fractal dimensions of one-dimensional cuts through these surfaces varied between 0.23 and 0.66, increasing with threshold value approaching the mean temperature. For thresholds close to the mean, no fractal behavior was found. Asymmetry in results for thresholds above and below the mean temperature was attributed to the asymmetry between updrafts and downdrafts in the convective surface layer.The temperature dissipation rate (TD) was also investigated. It was found to be strongly intermittent with large fluctuations of the intermittency exponent. Moments were analyzed in order to investigate multifractal properties of TD. Results indicate scaling in the range of 50–1000 (where is the Kolmogorov scale) and multifractal properties resembling those observed for passive scalar dissipation in laboratory flows.     

Tasting cheesescapes in Canterbury (New Zealand)

Food tourism is a means to connect agriculture produce and tourism activity. Food tourism allows destinations to convey the authenticity that comes from their food heritage, which is closely linked to natural and cultural landscapes. Food and landscapes in New Zealand are strongly related to dairy production, cheese production being one of the main features. This study showcases cheesescapes in Canterbury, the largest region in the South Island of New Zealand in terms of milk production. On one hand, thanks to food tourism, the producers can explore ways to diversify their production. On the other hand, visitors are able to identify with the inhabitants of a country and ‘taste’ a portion of its landscape through gastronomy.