assessment of multiple and interacting modes of soil loss in the karst critical zone southwest china swc abstract in southwest china swc soil loss is becoming a serious threat to the sustainable development of resources and the health of the environment a large number of studies have been conducted to investigate the causes e g environmental factors and human activities and impacts e g karst rocky desertification of soil loss however the following are some important problems related to soil loss in the karst of swc 1 although soil loss is caused by chemical weathering gravity and water interaction in karst the mechanisms by which soil loss takes place in the swc and their interaction are still not clear 2 subsurface soil loss varies under different geological and hydrological conditions and there is still no consensus on the common the ratio between surface soil erosion and underground soil loss 3 traditional methods for soil loss risk assessment are difficult to apply over the whole of swc and 4 a large number of studies have been published only in chinese and remain inaccessible to the international science community therefore a review paper is needed to address this gap and introduce the contributions of chinese researchers to soil loss in karst this paper proposes a novel modelling approach for the grouped soil loss styles and presents a comprehensive discussion for the mechanism causes and risk assessment of the various soil loss styles in swc karst

the soil leakage ratio in the mudu watershed china soil leakage in karst areas is an important geomorphic agent of environmental interest there are several viewpoints concerning soil leakage ratios one viewpoint states that the soil leakage ratio is high in karst regions whereas others consider that it is very low this paper s objective is to describe the soil leakage phenomena qualitatively and quantitatively in the chongqing karst china by conventional methods such as monitoring runoff plots and paint traces drawn on piles and walls found within runoff plots and by measuring the activity of the isotope 137cs at small medium and large spatial scales this paper s results show that soil filled karst cracks occurred at a small spatial scale with soil leakage ratios ranging from about 3 to about 34 at two abandoned quarries and six soil profiles with rock karst crack development the soil leakage ratio was almost zero at the medium spatial scale the soil leakage ratio was 4 50 and the surface soil erosion ratio was 95 50 of the total soil erosion at the large spatial scale it is concluded that soil leakage ratios in the study area were low at a large spatial scale and that cracks in karst were filled with soil at small spatial scales this paper s results indicate that soil leakage phenomena vary depending on the processes acting at the small medium and large spatial scales

geomorphometry and landform mapping what is a landform abstract starting from a concept of the land surface its definition and subdivision from digital elevation models dems is considered high resolution dems from active remote sensing form a new basis for geomorphological work which is moving on from consideration of whether data are accurate enough to how the surface of interest can be defined from an overabundance of data discussion of the operational definition and delimitation of specific landforms of varying degrees of difficulty from craters to mountains is followed by the applicability of fuzzy boundaries scaling usually allometric is shown to be compatible with the scale specificity of many landforms this is exemplified by glacial cirques and drumlins classification of a whole land surface is more difficult than extraction of specific landforms from it well dissected fluvial landscapes pose great challenges for areal analyses these are tackled by the delimitation of homogeneous elementary forms and or land elements in which slope position is considered the boundaries are mainly breaks in gradient or aspect but may also be in some type of curvature breaks in altitude are rare elementary forms or land elements are grouped together into functional regions landforms such as hill sheds it may often be useful to recognise fuzziness of membership or core and periphery of a surface object plains and etched or scoured surfaces defy most of these approaches and general geomorphometry remains the most widely applicable technique it has been applied mainly within arbitrary areas and to some extent to drainage basins but more experimentation with mountain ranges and other landforms or landform regions is needed geomorphological mapping is becoming more specialised and its legends are being simplified its incorporation into geographical information systems gis has required greater precision with definitions and the separation of thematic layers so that it is converging with specific geomorphometry and becoming more flexible and more applicable with a broader range of visualisation techniques

enhancement of coccolithophorid blooms in the bering sea by recent environmental changes 1 since 1997 ocean color satellite images have revealed large scale blooms of the coccolithophorid emiliania huxleyi in the eastern bering sea the blooms are often sustained over several months and have caused ecosystem changes in the arctic ocean as well as in the bering sea we examined continental shelf sediment profiles of alkenone a biomarker for e huxleyi covering the past 70 years the alkenone records suggest that large e huxleyi blooms are a novel feature in the bering sea as they have occurred only since the late 1970s recent changes in alkenone content were closely related to the 1976 77 climatic regime shift in the north pacific implying that warming and freshening of bering sea waters promoted e huxleyi blooms the production rate of diatoms total valves in sediment samples the dominant primary producers in the bering sea also increased during the past several decades however the ratio of alkenone content to total diatom valves in the sediments increased as e huxleyi production increased suggesting that the increase in the e huxleyi production rate frequently exceeded the increase in the diatom production rate overall our results indicate a possible subarctic region ecosystem shift driven by climate change

sea ice response to atmospheric and oceanic forcing in the bering sea abstract a coupled sea ice ocean model is developed to quantify the sea ice response to changes in atmospheric and oceanic forcing in the bering sea over the period 1970 2008 the model captures much of the observed spatiotemporal variability of sea ice and sea surface temperature sst and the basic features of the upper ocean circulation in the bering sea model results suggest that tides affect the spatial redistribution of ice mass by up to 0 1 m or 15 in the central eastern bering sea by modifying ice motion and deformation and ocean flows the considerable interannual variability in the pattern and strength of winter northeasterly winds leads to southwestward ice mass advection during january may ranging from 0 9 1012 m3 in 1996 to 1 8 1012 m3 in 1976 and averaging 1 4 1012 m3 which is almost twice the january may mean total ice volume in the bering sea the large scale southward ice mass advection is constrained by warm surface waters in the south that melt 1 5 1012 m3 of ice in mainly t

morphology of fore reef slopes and terraces takapoto atoll tuamotu archipelago french polynesia central pacific the tectonic sea level and coral growth control abstract a dataset of 41 bathymetric profiles detected by satelline imagery and echo sounding to a maximum depth of 38 m along the fore reef slopes of takapoto atoll tuamotu plateau french polynesia central pacific were qualitatively and quantitatively analyzed in order to identify the main geomorphological features in addition scuba diving investigations from a selected site resulted in defining coral composition and cover rate six distinct fore reef sectors were morphologically differentiated on the basis of seaward extension and slope gradient only the north end and a restricted area of the mid south east side extend seawards over an average distance of 150 m with a relatively low gradient 23 38 most of the outer slope areas are narrow 10 m high outer reef crest like reliefs 0 5 m 1 5 m high pinnacles 2 m 17 m high coral heads

regulation of algal blooms in antarctic shelf waters by the release of iron from melting sea ice during summer 1995 96 we measured iron in the water column and conducted iron enrichment bottle incubation experiments at a station in the central ross sea 76 30 s 170 40 w first in the presence of melting sea ice and 17 days later in ice free conditions we observed a striking temporal change in mixed layer dissolved iron concentrations at this station from 0 72 2 3 nm with sea ice present to 0 16 0 17 nm in ice free conditions these changes were accompanied by a significant drawdown in macronutrients and an approximate doubling of algal diatom biomass our incubation experiments suggest that conditions were iron replete in the presence of sea ice and iron deficient in the absence of sea ice we surmise that bioavailable iron was released into seawater from the melting sea ice stimulating phytoplankton production and the biological removal of dissolved iron from the mixed layer until iron limited conditions developed these observations suggest that the episodic release of bioavailable iron from melting sea ice is an important factor regulating phytoplankton production particularly ice edge blooms in seasonally ice covered antarctic waters

sea ice derived dissolved iron and its potential influence on the spring algal bloom in the bering sea 1 observational and modeling studies in the bering sea indicate that changes in the seasonal ice cover and time of ice retreat influence open water productivity in particular the timing of the spring bloom and its phytoplankton community composition are affected dissolved iron dfe data in the water column and ice cores collected during the 2007 bering ecosystem study best cruise indicate that the melting ice provided substantial dfe to the water column the additional dfe input from melting sea ice could be biologically important along the outer shelf and shelf break where in ice free areas insufficient dfe 20 m variability in sea ice dynamics are likely to result in a varying supply of dfe to the outer shelf and shelf break in early spring and to contribute to the observed changes in the timing and community composition of the spring phytoplankton bloom

hydrological response and soil detachment rate from dip anti dip slopes as a function of rock strata dip in karst valley revealed by rainfall simulations rock dip angle plays a significant role in surface hydraulic characteristics and leads to different spatial distribution of water and soil loss in karst trough valleys in this study the rock dip angle effect on the hydraulic characteristics and soil detachment rate on dip anti dip slopes was explored via rainfall simulations and a steel experimental flume the rainfall intensities ranged from 30 to 90 mm h and the rock dip angles varied from 10 to 60 the results revealed that i surface runoff on the dip slope was higher than that on the anti dip slope whereas underground runoff presented opposite results the 30 rock dip angle presented the critical flow velocity for the anti dip slope and the flow velocity reduced as the rock dip angle of the dip slope increased ii laminar water flow occurred on the dip anti dip slope re was 500 in all cases for the anti dip slope the re value reduced by 3 53 89 79 the fr value reduced by 34 13 73 04 and the f value increased by 61 07 93 78 compared with that of the dip slope iii a linear function model can describe the relationship between the soil detachment rate and hydrodynamic parameters w and e it was found that w was the best of the hydrodynamic parameters to describe the soil detachment rate these results could provide valuable information for establishing a national scale empirical soil erosion model for karst trough valley

insular erosion isostasy and subsidence organic reefs and shore erosion record the intersection of sea level with islands from this record it is possible to reconstruct the history of vertical movement of the islands and the adjacent deep sea floor including midplate swells as judged by coral thickness islands with barrier reefs sink as though they were on thermally youthful crust regardless of the actual age reefless islands do not sink until truncated by erosion apparently thermal subsidence is balanced by isostatic uplift in response to erosion barrier reefs prevent wave erosion of encircled volcanoes and capture products of stream erosion so that isostatic uplift is eliminated insular shelves widen initially at rates of 0 6 to 1 7 kilometers per million years the rates decrease with time thus the subsidence of islands depends on the size of the is land and the presence of reefs and it may not always be the same as that of the surrounding oceanic crust

response of coral reefs to climate change expansion and demise of the southernmost pacific coral reef received 21 may 2010 revised 20 june 2010 accepted 6 july 2010 published 3 august 2010 1 coral reefs track sea level and are particularly sensitive to changes in climate reefs are threatened by global warming with many experiencing increased coral bleaching warmer sea surface temperatures might enable reef expansion into mid latitudes here we report multibeam sonar and coring that reveal an extensive relict coral reef around lord howe island which is fringed by the southernmost reef in the pacific ocean the relict reef in water depths of 25 50 m flourished in early holocene and covered an area more than 20 times larger than the modern reef radiocarbon and uranium series dating indicates that corals grew between 9000 and 7000 years ago the reef was subsequently drowned and backstepped to its modern limited extent this relict reef with localised re establishment of corals in the past three millennia could become a substrate for reef expansion in response to warmer temperatures anticipated later this century and beyond if corals are able to recolonise its surface citation woodroffe c d b p brooke m linklater d m kennedy b g jones c buchanan r mleczko q hua and j zhao 2010 response of coral reefs to climate change expansion and demise of the southernmost pacific coral reef geophys res lett 37 l15602 doi 10 1029 2010gl044067

erosion creep collapse mechanism of underground soil loss for the karst rocky desertification in chenqi village puding county guizhou china carbonate rocks distribute widely in china the total area of the carbonate rocks is about 3 430 000 km 2 and the exposed area of the carbonate is approximately 13 of china s territory in 2003 soil loss in yunnan guizhou and guangxi provinces reached 179 600 km 2 which is almost 40 1 of the total area causing rocky desertification in this study the erosion creep collapse mechanism of underground soil loss for the karst rocky desertification in chenqi village puding county guizhou province is proposed the mechanism occurs under the following geological environment slope surface undulation underlying bedrock surface fluctuation and thin and inhomogeneous soil overlying overlying soil generation by bedrock weathering underground karst development and large groundwater depth and lying water table under the bottom of soils the erosion creep collapse mechanism of underground soil loss in the karst slopes is explained as follows power loss due to human cultivation activities that destroy the soil structure hydraulic force formed by rainfall infiltration wet dry cycle generated by rainfall erosion effect caused by rainfall penetration creeping and flowing of plastic stream soil and collapse the erosion creep collapse mechanism of underground soil loss has seven steps disturbance of soils filled in underground karst cave by human activities internal soil erosion and partial collapse caused by hydraulic power internal free surface formation within the soil in the filled karst cave internal soil creeping soil pipe formation soil pipe collapse and ground surface collapse and filling soil loss develops slowly and sudden transportation occurs by collapse soil loss can be explained by the proposed mechanism and soil loss can be prevented by controlling soil collapse

theoretical estimates of light reflection and transmission by spatially complex and temporally varying sea ice covers the reflection absorption and transmission of light at visible and near infrared wavelengths by snow and ice covers is important for a number of geophysical problems the focus of this paper is on the reflection and transmission of light by spatially inhomogeneous and temporally varying sea ice covers this is investigated using a two stream multilayer radiative transfer model in the wavelength region from 400 to 1000 nm the model is computationally simple and utilizes the available experimental data on the optical properties of sea ice the ice cover is characterized as a layered medium composed of selections from nine distinct snow and ice types three case studies are presented illustrating values of spectral albedo transmittance and transmitted photosynthetically active radiation par for 1 a spatially inhomogeneous ice cover 2 a uniform ice cover as it undergoes a melt cycle and 3 a temporally changing spatially variable ice cover results indicate that small scale horizontal variations in snow depth and ice thickness can cause light transmission to change over 3 orders of magnitude dramatic changes in light reflection and transmission are predicted in the early part of the melt season as the ice cover evolves from an opaque snow covered medium to translucent bare or ponded ice

characteristics of red clay creep in karst caves and loss leakage of soil in the karst rocky desertification area of puding county guizhou china the loss of surface soil and water in the karst rocky desertification area of carbonate rock in chenqi village puding county guizhou province was monitored in this study the results show that the major form of surface soil loss in the area is the loss of soil through underground channels a creep test of red clay formed by loss through underground channels was conducted the results of the test show that the creep curve of the red clay samples includes two stages attenuation creep stage and stable creep stage the creep law for the red clay samples in the karst cave can be described by buger s model the parameters of buger s equation were deduced by fitting the creep curve which provides the reference for analyzing the surface soil loss leaking through the underground channels

new evidence for drowned shelf edge reefs in the great barrier reef australia we present four new high resolution multibeam bathymetry datasets from the shelf edge of the northern great barrier reef gbr analysis of these data combined with chirp sub bottom profiles and existing submersible observation data provides a fresh insight into the detailed morphology and spatial distribution of submerged reefs and terraces at the shelf edge an extensive and persistent line of drowned shelf edge reefs exist on the gbr margin in about 40 to 70 m they appear as barrier reefs up to 200 m wide and comprising twin parallel ridges of rounded pinnacles subtle yet consistent terrace and step features lie between 78 and 114 m seaward of the shelf edge reefs in the southern study area submersible observations confirm that the drowned reefs now provide a favorable hard substrate for live soft corals and algae they form a consistent and extensive seabed habitat that extends for possibly 900 km along the gbr shelf edge the submerged reef and terraces features may reflect a complex history of growth and erosion during lower sea levels and are now capped by last deglaciation reef material

factors influencing physical structure and lower trophic levels of the eastern bering sea shelf in 2005 sea ice tides and winds abstract in spring and fall 2005 cross and along shelf transects were sampled to evaluate the influence of physical forcing including sea ice tides and winds on the lower trophic levels of the bering sea ecosystem the hydrography nutrients chlorophyll and zooplankton abundance and species composition were all affected by the presence or absence of sea ice on a north south transect along the 70 m isobath in may shelf waters between 59 n and 62 n were cold and relatively fresh and benthic invertebrate larvae and chaetognaths were a significant fraction of the zooplankton community while to the south the water was warmer saltier and the zooplankton community was dominated by copepods the position of the transition between ice affected and ice free portions of the shelf was consistent among temperature salinity nutrients and oxygen this transition in the hydrographic variables persisted through the summer but it shifted 150 km northward as the season progressed while a transition also occurred in zooplankton species composition it was farther north than the physical chemical transition and did not persist through the summer mooring data demonstrated that the change in the position of the transition in physical and chemical properties was due to northward or eastward advection of water onto and across the shelf from south to north along the 70 m isobath tidal energy decreased resulting in a less sharply stratified water column on the northern portion of the middle shelf as opposed to a well defined two layered system in the southern portion this more gradual stratification in the north permitted a greater response to mixing from winds which were homogeneous from north to south thus the physical and biological structure at any one location over the middle shelf is dynamic over the course of a year and results from a combination of in situ processes and climate mediated regional forcing which is dominated in most years by sea ice

a new coral reef province in the gulf of carpentaria australia colonisation growth and submergence during the early holocene abstract multibeam sonar mapping drill cores and underwater video data have confirmed the existence of a previously unknown coral reef province in the gulf of carpentaria australia seven reefs comprised of coral limestone that support living corals have been mapped so far and as many as 50 other reefs may exist in the region u th ages show that reef growth commenced shortly after limestone pedestals were submerged by rising sea level around 10 5 kyr bp making them the oldest holocene reefs known in australia reef growth persisted for 2 0 kyr but it had ceased at most locations by 7 0 kyr bp measurements of reef growth rates 0 95 to 4 m kyr 1 indicate that the reefs were unable to keep pace with contemporaneous rapid sea level rise 10 m kyr 1 which is consistent with a give up reef growth history core samples from reef platforms demonstrate that pleistocene limestone is exposed at depths of 27 and 30 m below present mean sea level these depths represent regionally significant phases of reef growth during a prolonged sea level still stand we conclude that the reefs are therefore mostly relict features whose major phase of growth and development relates to an earlier pre holocene sea level still stand

tasman front shifts and associated paleoceanographic changes during the last 250 000 years foraminiferal evidence from the lord howe rise abstract the paleoceanography of the tasman sea over the past 250 000 years was studied using benthic 75 m size fraction and planktonic foraminifera 149 m size fraction from three cores collected along 162 e traverse between 25 s and 30 s on the lord howe rise planktonic foraminiferal oxygen isotope stratigraphy dates the cores between ois 1 and 11 r mode cluster and q mode factor analyses were carried out on benthic foraminiferal faunas and q mode factor analysis and the modern analog technique mat were used in analyzing planktonic foraminiferal faunas distinct benthic faunas across latitude from north 25 s to south 30 s and 35 s reflects the difference in primary productivity level in the overlying surface water the mat result is thought to express latitudinal shifts of the tasman front over the last 250 000 years with 1 the tasman front at 35 s during the oxygen isotope stage ois 1 post glacial period 2 migration of the front nearby 25 s during the last glacial period ois 2 ois 4 and slightly northward of its present position during the penultimate glacial period ois 6 and 3 a return of the front to near 35 s during ois 5 and ois 7 based on time series and spatial variations of benthic foraminiferal factor typified by pseudoparrella exigua and uvigerina peregrina and one variety southern winter mixing and convection along the tasman front may have strengthened during the interglacial ois 7 in particular

spatial and year to year patterns in new and primary productivity in sea ice melt regions of the eastern bering sea abstract four years of data on for new nitrate regenerated ammonium and primary carbon productivity 2007 through 2010 confirm the elevated productivity associated with the marginal ice zone miz of the eastern bering sea ebs in spring the greatest levels of productivity were associated with ice melt regions along the western edge of the ice pack population seeding and the shallowing of the mixed layer depth near the ice edge were less important in the development of elevated miz productivity than was the amount of ice melt entering surface water suggesting that ice contributed substances stimulating phytoplankton growth based on ice melt as an index of bloom development primary productivity continued to increase after new productivity peaked at the miz environments with optimal growth conditions new productivity averaged 18 6 mmol n m 2 d 1 with a ratio of 0 61 and primary productivity averaged 492 mmol c m 2 d 1 although these features were consistently recorded in late april early may they varied with the dynamics of ice cover whose retreat was later in 2008 relative to 2007 and 2009 the intense but localized miz blooms appear to be under sampled in ocean color imagery under ice productivity was generally low ave no3 0 45 mmol n m 2 d 1 ave primary prod 4 16 mmol c m 2 d 1 although larger values were measured under the western edge of the ice pack and in the st lawrence polynya region the advection of ice and water may contribute to the large values under the western ice edge and the highly transparent new ice may play a role in the polynya new and primary productivity rates of under ice samples were significantly inhibited when exposed to ice free irradiance levels in situ productivity could be estimated to 35 from rates measured on deck by adjusting for the impact of ice on submarine light the carbon to nitrate uptake ratio was closely related to specific carbon production in the in situ incubations

physical forcing and nutrient conditions associated with patterns of chl a and phytoplankton productivity in the southeastern bering sea during summer abstract measurements of nutrients primary 14 c productivity and new nitrate productivity collected in the southeastern bering sea in july and august 2004 together with measurements from july 1981 are used to characterize the regional production system during summer and to analyze the major physical and nutrient factors controlling biological patterns the patterns of surface productivity suggested by the two different summers were remarkably similar in the regions of data overlap and agree with recent compilations of summer conditions from remotely sensed data summer was characterized by low production in the middle and outer shelf associated with surface mixed layers that were stabilized by heat elevated productivity was restricted to regions associated with the surface expression of thermohaline fronts as well as to tidally mixed regions adjacent to and between the pribilof islands based on chl a and productivity measurements the biological impact of the shelf break front of the southeastern bering sea extends at least as far inshore as the pribilof islands the existence of elevated summer productivity associated with a recently identified shelf partition front between the pribilof domain and the middle shelf domain east of st paul island was confirmed and its thermohaline nature resulting from cumulative intrusions of slope derived water is described yearly estimates of new and primary productivity compiled for the various biophysical regimes range from 1800 mmol n m 2 yr 1 and 170 g c m 2 yr 1 at the shelf break front to less than 700 mmol n m 2 yr 1 and 100 g c m 2 yr 1 in oceanic and coastal waters we hypothesize that trace metals rather than macronutrients or grazing likely restrict the seaward extent of elevated production at the shelf break front iron may be supplied to the front by isopycnal mixing from deeper shelf waters that were in contact with sediments by extending elevated production throughout the summer the thermohaline and tidal fronts enhance the coupling of primary production to epipelagic food webs for the large populations of fish birds and mammals in the region changes in the intensity or location of these frontal systems may impact populations that forage in them from the nearby pribilof islands

effects of rock fragments on soil erosion by water at different spatial scales a review this paper reviews the various effects of rock fragments on soil erosion by water since these effects are scale dependent they are investigated at three different nested spatial scales the microplot 4 10 6 100m2 the mesoplot 10 2 102 m2 and the macroplot 101 104 m2 for each scale the corresponding process mechanisms are discussed particular attention is paid to the effects of rock fragment cover on the intensity of soil erosion processes at the mesoplot scale i e on interrill areas rock fragments at the soil surface can have negative as well as positive effects on sediment yield these ambivalent effects are conditioned by the type of fine earth porosity soil surface slope vertical position and size of rock fragments and by the occurrence of horseshoe vortex erosion at the microplot scale i e the soil surface area which is covered by a single rock fragment and at the macroplot scale i e upland areas where both interrill and rill erosion takes place rock fragments at the soil surface have a negative effect on sediment yield in these two scales rock fragments can thus be considered as natural soil surface stabilizers at the macroplot scale the mean decrease of relative interrill and rill sediment yield with rock fragment cover can be expressed by an exponential decay function the scatter of the data indicates that a given rock fragment cover can have different efficiencies in reducing interrill and rill sediment yield depending on the varying intensities of the hydrological and erosion subprocesses these findings have implications for erosion modelling and soil conservation

significance of preferential flow at the rock soil interface in a semi arid karst environment abstract in many semi arid environments the surface materials are frequently characterized by thin soils and large proportions of bare rock both of which are expected to considerably influence infiltration and groundwater recharge processes in this study small plot scale irrigation experiments in combination with dye tracer application as well as real time and subsequent soil moisture measurements and soil particle size analysis were conducted to investigate the significance of preferential flow at the rock soil interface large scale assessments of soil depth and surface type distribution were used to upscale the findings of the irrigation experiments to the scale of a complete hillslope and further to estimate percolation properties of a hypothetical rainfall event the two experimental plots were each located in the west bank mountains close to ramallah each irrigation experiment was designed with 50 mm of precipitation applied on an area of 1 m 2 during the course of ca 2 5 h each irrigation plot had a surface share of approximately 50 rock outcrop and 50 soil surface percolation properties were investigated by subsequent soil moisture measurements at high spatial resolution on vertical soil profiles on the irrigated plot dye tracer application on the rock outcrop during the sprinkling allowed for tracking of resulting outcrop runoff in the subsurface the soil depth survey included 2100 measurement points on 7 transects which allowed the estimation of local soil depth distribution results of the irrigation experiments showed that precipitation induced runoff from rock outcrops continued below ground as preferential flow along the rock soil interface while water from the soil surface percolated mainly vertically and much more homogeneously this was evident from the high density soil moisture measurements as well as from the dye tracer patterns outcrop runoff percolated faster and to greater depths than water infiltrating directly from the soil surface thus possessing a greater potential for groundwater recharge

role of underground fissure flow in near surface rainfall runoff process on a rock mantled slope in the karst rocky desertification area abstract because of the complex near surface double layer geologic structure i e surface and underground fissures of slopes in karst regions it is difficult to collect data on all flows especially the flows generated in underground fissures this lack of information leads to a poor understanding of the rainfall runoff process associated with soil loss in karst landscapes the goal of this study was to determine the output characteristics of surface subsurface and underground fissure flows and their conversion relationships as well as the role of underground fissure flow in the near surface rainfall runoff process using rainfall experiments the results revealed the following findings light rainfall intensities 15 and 30 mm h generated subsurface lateral flow and underground fissure flow whereas greater rainfall intensities generated surface runoff in addition to subsurface and underground flows ii the runoff drainage depths of all the above flows increased with increasing rainfall intensity while the runoff drainage coefficient exhibited no obvious regular change except for the surface runoff moreover the distribution ratio of surface runoff to total flow also increased with increasing rainfall intensity but decreased with increasing underground fissure degree while the distribution ratio of underground fissure flow exhibited the opposite trend iii underground fissure flow with distribution ratios of 27 8 78 0 dominated the total flow yield this study has significance for controlling soil erosion and water shortage in the karst rocky desertification region and also improves the understanding of the near surface rainfall runoff process in this region

seismic stratigraphy and development of the shelf edge reefs of the great barrier reef australia extensive shelf edge reefs sers and terraces are common along the seaward margin of the great barrier reef gbr we aim to better understand the architecture of the sers deposited during a poorly constrained period the last glacial maximum lgm and early postglacial a dense array of topas seismic lines was interpreted at hydrographers passage in the southern central gbr following a seismic stratigraphic approach ground truthed against integrated ocean drilling program expedition 325 iodp exp 325 sediment core data we interpreted two prominent sub bottom reflectors an upper r1 and a lower r2 that separate three seismic units according to our borehole to seismic correlation in a representative location r1 corresponds to a downward increase of impedance which is also reflected in lithological and diagenetical changes r2 is poorly constrained but likely also represents a lithological contrast seismic velocities were also estimated in the same borehole location for inter reef deposits and reef framework together with the geomorphic interpretation we reconstructed velocity maps for the study area leading to the generation of a 3d geomorphic model of the antecedent topography or substrate and volumetric calculations geomorphic and thickness trends suggest a strong relationship between the antecedent topography and the morphology of the sers the distribution of seismic facies identified in the dataset coupled to geomorphic trends and published sea level curves allowed us to reconstruct the lgm to postglacial depositional history of these deposits our interpretation suggests significant regressive reefal accumulations formed on top of a marine flooding surface represented by reflector r2 during the sea level fall to the lgm r1 is the distal equivalent of an unconformity previously identified in the gbr inner and mid shelf widely affected by subaerial exposure on top of which a postglacial transgressive mainly reefal unit 1 was deposited two zones are distinguished 1 a distal zone below 80 mbsl with thick deposits displaying fringing reef morphologies influenced by the late lgm fall and subsequent early postglacial rise in sea level and by the updip availability of substrate and 2 a proximal zone above 80 mbsl of enhanced vertical growth with unfilled lagoons resulting from the lack of lateral substrate and the rapid sea level rise our seismic stratigraphic model of the development of the sers sediment volumetrics and 3d reconstruction of the antecedent topography provides a foundation for future forward modeling stratigraphic studies

the geomorphology of the flanks of the lord howe island volcano tasman sea australia abstract the flanks of mid ocean volcanoes are inherently unstable features especially in the constructional phase of development when the volcano is active lateral and vertical stresses are placed on the volcanic edifice as it builds with the flanks continuing to be unstable up to at least 1 ma after volcanism has ceased the flanks of the lord howe island volcano record this period of greatest instability and a subsequent period in which marine and subaerial erosion have dominated its geomorphic evolution lord howe island lies in the tasman sea of the southern pacific region and is the subaerial remnant of a miocene mid ocean volcano the island has only recently entered reef building seas and therefore has been subject to marine erosive processes over the past 5 6 ma the island is unique as it sits on the stable drowned continental crust of the lord howe rise rather than oceanic crust like many other mid plate basaltic islands multibeam sonar bathymetry data were collected to a depth of 3500 m where the island flanks grade into the surrounding planar sea floor several slump features are evident the largest being over 130 km2 in area these features are inferred to be old late tertiary based on an extensive cover of marine sediment as indicated by low multibeam backscatter intensity and subdued topography most likely the slumps formed during the immediate post eruptive stage of volcano evolution before the bulk of the subaerial portion of the volcano was removed by marine erosion flank processes are now dominated by the deposition of carbonate sediment composed of mollusc and foraminiferal remains based on radiocarbon and stable isotope analyses of a sediment core 760 m depth collected on a trough in the centre of the volcanic edifice quaternary sediment was likely deposited predominantly during glacial periods the erosional morphology sediment cover and tectonic stability of the region suggest that the flanks of the volcano are at present relatively stable

geomorphology of submerged reefs on the shelf edge of the great barrier reef the influence of oscillating pleistocene sea levels the submerged reefs on continental margins and surrounding oceanic islands are important archives of past climates eustatic sea level oscillations and oceanographic processes australia s north eastern submerged shelf edge reefs have previously been explored but all studies have been limited by either low resolution single beam profiles or by their limited spatial extent the aim of this study is to improve the understanding of the origin and development of submerged shelf edge reefs terraces and related features on the great barrier reef gbr and the influence of pleistocene sea level oscillations on their distribution and geomorphology we investigated the first large scale 1400 km2 3d bathymetry and acoustic backscatter dataset of four widely spaced sites located across ca 650 km along the shelf edge at ribbon reefs 1 5 noggin pass viper reef and hydrographers passage we provide a comprehensive description and systematic classification of the shelf edge features and constrain their spatial distribution and geomorphologic variability using a wide range of quantitative morphometrics fifteen features are defined four of which are the focus of this study including terraces pinnacles ridges and channels using modern reefs within the gbr for comparison we interpret these as fringing reefs patch and barrier reefs and tidal channels respectively the influence of gross shelf geomorphology and oceanographic factors driving the observed variability within and between sites is discussed in conjunction with mid late pleistocene sea level oscillations we observed two distinct types of reef growth characterised by the degree of development which we interpret as analogous to juvenile and mature modern reefs of the gbr juvenile reefs are very common and occur within each site at depths of less than 50 m to greater than 100 m they are defined as discontinuous peaked barrier reefs peaked patch reefs and fringing reefs mature reefs are less common and develop exclusively at a depth range of ca 50 70 m these reefs are defined as flat topped continuous barrier and double barrier reefs through a comparison with published mid late pleistocene sea level oscillations we note that the depth range of mature reefs is consistent with the depth of repeated low amplitude 20 m eustatic sea level oscillations and independent of the relative time spent at sea level we conclude that repeated low amplitude sea level rises provide the much needed accommodation space for vertical accretion that is not provided during stillstands without inducing reef drowning which can be caused by high amplitude sea level rise low amplitude sea level falls are also less detrimental than high amplitude falls in terms of habitat compression together the effects of enhanced reef accretion and limited habitat compression at depths of 50 70 m have lead to a concentrated net gain in vertical relief that is not observed elsewhere on the shelf edge

dating reservoir deposits to reconstruct sediment yields from a small limestone catchment in the yimeng mountain region china abstract in this study we use reservoir deposits to reconstruct sediment yields over the past 50 years from the quananzi catchment a small limestone catchment in the yimeng mountain region china three sediment cores were collected from the reservoir and the chronology of each core was established using 137cs and 210pbex dating the area specific sediment yields ssy for different time periods since dam construction were estimated from each core by referring to the original capacity curves of the reservoir the estimated ssy from the quananzi catchment in each core for each period ranged between 0 9 0 3 and 2 6 0 9 t ha 1 y 1 with a mean value of 1 8 0 6 t ha 1 y 1 which is low compared with reported ssy from catchments worldwide the mean value was only about 1 7 of the equivalent value reported from the jiangzhang catchment in the granite area of the yimeng mountain region this low ssy reflects the shortage of erodible luvisols resistance to erosion and the limited effect of human disturbance in this small limestone catchment the decrease in ssy from 1959 to1972 suggests that the effect of the deforestation that occurred in 1958 on soil erosion decreased with time the continual increase of ssy through the two subsequent periods after 1972 reflects the expansion and intensification of cultivation during this time however the decreased ssy over the latest period of 1998 2012 can be related to the limitations imposed by the karst landscape on cultivation and to the impact of increasing numbers of residents leaving the area since the end of the 1990s to become temporary migrant workers elsewhere resulting in a decrease in human activity in the area overall the trend in ssy reflects the general history of changing human disturbance in this small limestone catchment over the past 50 years the results indicate that reservoir deposits provide a means of estimating the historical sediment yields from a karstic environment

occurrence mechanism and prediction of rocky land degradation in karst mountainous basins with the aid of gis technology a study case in houzhai river basin in southwestern china rocky desertification is a severe ecological issue threatening and constraining regional sustainable development in karst mountainous areas like houzhai river basin in southwestern china the results indicate that slope gradient and altitude are closely associated with occurrence of rocky desertification in the study region and there are some significant correlations between rock outcrop and slope gradient r 0 363 p 0 001 and between rock outcrop and altitude r 0 0 336 p 0 001 slope gradient and altitude are key factors contributing to rocky desertification in the studied basin therefore special attention should be paid to sloping lands that have greater slope gradients or altitudes to prevent and control the rocky desertification in a karst mountainous basin as the houzhai river basin furthermore it might be possible to predict the occurrence of rocky desertification using neural networks on the basis of geographical characteristics and human disturbance the correlation coefficients between observed values and predicted values ranged from 0 728 to 0 905 with a mean value of 0 851 ten times repeats the present study also indicates that human disturbance has little effect on rocky desertification however further studies should be conducted to interpret the effects of agricultural activities on the occurrence of rocky desertification

late quaternary palaeoceanography of the tasman sea the benthic foraminiferal view abstract the benthic foraminiferal content of four gravity cores from the east tasman plateau 2450 m and 2667 m water depth and the lord howe rise 1349 m and 1448 m water depth was examined in order to determine late quaternary palaeoceanographic changes in the tasman sea in all cores benthic foraminifera demonstrate the glacial interglacial cyclicity through changes in assemblages and abundance abundances range from about 400 to 1200 specimens per gram of dry sediment over the last 400 kyr abundance patterns differ between the northern between 31 s and 33 s and the southern sites between 43 s and 44 s in the southern cores a significantly increased benthic foraminiferal abundance indicates high nutrient flux and quality perhaps continuously during stage 5 the northern cores on the other hand display this signal for stage 6 this reversed pattern is recognizable for other glacial episodes as well as for interglacials but the trend is less distinctive enhanced sea surface productivity in the tasman sea during the last glacial cycle is recognized from benthic foraminiferal assemblages but the pattern appears highly variable and complex the data suggest that for the past relocation of recent high productive oceanographic features sensu yoder et al 1994 in the tasman sea such as the tasman front the subtropical convergence the east australian current and perhaps the east australian eddy field tranter et al 1982 are reflected in the benthic formainiferal abundances in the cores increased foraminiferal abundance during glacials on the lord howe rise indicate a slight northward shift of the tasman front data from the east tasman plateau show a more complex situation the faunal pattern in the cores probably reflect a southward shift of the eddy field during glacials and a slight northward shift of the subtropical convergence during interglacials

late pleistocene palaeocenography of the tasman sea implications for the dynamics of the warm pool in the western pacific quantitative analyses of planktonic foraminifera from 47 core top samples spatially distributed through the tasman sea and cores rc12 113 e36 23 dsdp sites 588 592 593 and odp site 828a from a n s transect supplemented with stable isotope analyses indicate that three planktonic foraminiferal assemblages defined by factor analysis on core top material correlated with three hydrographic modes defined on the basis of sea surface temperatures temperature profiles seasonal changes in temperature and mixed layer depth similar assemblages were found in down core material along the tasman sea transect that combined with semi quantitative analyses of foraminiferal assemblages provinces and the coiling ratio of globorotalia truncatulinoides allows reconstruction of the position of the tasman front or the subtropical divergence during the late brunhes chron the results indicate that the tasman front migrated from its present position at 30 s to 26 s during the last glacial maximum the northward migration of the tasman front may indicate a reduction in volume of the equatorial warm pool and or an increase in the strength of cool subtropical water masses the late pleistocene distribution of g truncatulinoides left coiling from appears to be related to the formation of subantarctic mode water thermostads this relationship may explain the evolutionary origin of this species in the southwest pacific at 2 4 ma simultaneously with the onset of late pliocene glaciations the past position of the subtropical convergence is reconstructed by means of coilingv directions in neogloboquadrina pachyderma the convergence apparently migrated slightly north of 43 s core e36 23 during glacial stages 6 10 and 12

controls of infiltration runoff processes in mediterranean karst rangelands in se spain semiarid karst landscapes represent an important ecosystem surrounding the mediterranean basin for which little is known on runoff generation knowledge of the sources and patterns of variation in infiltration runoff processes and their controls is important for understanding and modelling the hydrological functions of such ecosystems the objectives of this paper are to determine the infiltration rates and their controls in a representative mountain karst area sierra de gador se spain at micro plots and to investigate the integrated response of rainfall on a typical hillslope rainfall simulations in micro plots and natural rainfall runoff monitoring on a hillslope were carried out complementarily we investigated the role of soil surface components vegetation rock outcrop fracture and soil crust topographic position antecedent soil moisture and rainfall characteristics in regulating infiltration runoff processes results of rainfall simulation revealed the importance of vegetation cover and the presence of rock fractures in promoting the infiltration in the limestone karst landscape while bare patches and rock outcrops acted as sources for runoff all plots with 50 vegetation cover had no runoff with up to 55mmh 1 of simulated rain in contrast nearly all bare plots had runoff under the same simulated rain with runoff coefficients ranging from 3 1 to 20 6 on dry soil surface conditions and from 2 0 to 65 4 on wet soil surfaces runoff coefficients amounted to 59 0 79 5 for rock outcrops without cracks but were drastically reduced by the presence of cracks the surfaces with rock fragments resting on the soil generally located in the middle of the slopes prevented more effectively the runoff generation than those surfaces where rock fragments were embedded in the top soil antecedent soil moisture had significant impact on runoff generation with wet soil having doubled runoff coefficient shortened time to runoff and increased runoff rate compared to the same but dry soil linear regressions indicated that the main controls for constant infiltration rate were the cover percentages of vegetation and litter plus rainfall intensity while the major controls for runoff coefficient were the bare soil and vegetation coverage plus rainfall intensity high infiltration rates measured at the micro plots agreed with low intra event runoff coefficients mostly below 1 observed under natural rainfalls at the hillslope runoff depth and coefficient at the hillslope was significantly correlated with rainfall depth maximum hourly rainfall intensity and antecedent precipitation over 20days ap20 during the 1 5 year monitoring period from sep 2003 to mar 2005 the overall infiltration was 41 of the total rainfall amount and the maximum infiltration rate was almost 94 of the largest single rainfall event the results from this study contribute to improved understanding of the magnitude and controls of the surface runoff in semiarid karst mountain areas 2011 elsevier b v

glacial interglacial changes in the east australian current the east australian current eac is the western boundary current of the south pacific gyre transporting warm tropical waters to higher southern latitudes recent modelling shows that the partial separation of the eac 32 s and the coupled formation of the tasman front 34 s are caused by a steep gradient in the zonally integrated wind stress curl analysis of oxygen isotope ratios 18o in the planktonic foraminifer globigerinoides ruber from sediment cores from the coral sea and tasman sea indicates that the eac separation shifted northward to between 23 and 26 s during the last glacial we suggest these results indicate a significant change in the pacific wind stress curl during the glacial given recent evidence for el nino like conditions in the pacific during the last glacial with a reduction in the east west sea surface temperature sst gradient we suggest that weaker trade winds combined with more northerly stronger westerlies were associated with a change to the wind stress curl which repositioned the eac separation and tasman front in contrast by 11 ka bp the eac separation was forced south of 26 s this southward shift was synchronous with a rapid warming of tropical ssts and the onset of a la nina like sst configuration across the tropical pacific it appears that the south pacific trade winds strengthened accordingly causing the eac to readjust its flow this readjustment of the eac marks the onset of modern surface ocean circulation in the southwest pacific but the present eac transport was only achieved in the late holocene after 5 ka bp

comparison of warm and cold years on the southeastern bering sea shelf and some implications for the ecosystem the southeastern middle shelf of the bering sea has exhibited extreme variability in sea ice extent temperature and the distribution and abundance of species at multiple trophic levels over the past four decades from 1972 2000 there was high interannual variability of areal extent of sea ice during spring march april in 2000 this shifted to a 5 year 2001 2005 period of low ice extent during spring which transitioned to a 4 year 2007 2010 period of extensive sea ice high low areal extent of sea ice in spring was associated with cold warm water column temperatures for the following 6 7 months the ocean currents also differed between warm and cold years during cold years the monthly mean currents over the shelf were largely westward while in warm years the direction of currents was more variable with northward flow during december february and relatively weak flow during the remainder of the year the types and abundance of zooplankton differed sharply between warm and cold years this was especially true during the prolonged warm period 2001 2005 and cold period 2007 2010 and was less evident during the years of high interannual variability during the warm period there was a lack of large copepods and euphausiids over the shelf however their populations rebounded during cold period small crustacean zooplankton taxa did not appear to vary between and warm and cold years for both walleye pollock and pacific cod year class strength recruitment was low during the prolonged warm period but improved during the following cold period year class strength did not appear to vary as a function of warm and cold years during the period of high year to year variability also recruitment of arrowtooth flounder a predator of pollock and cod did not appear influenced by the warm or cold years finally the distribution and relative abundance of fin whales appeared to differ in warm and cold years with fewer whales on the southeastern middle shelf during warm years

determination of water depth with high resolution satellite imagery over variable bottom types a standard algorithm for determining depth in clear water from passive sensors exists but it requires tuning of five parameters and does not retrieve depths where the bottom has an extremely low albedo to address these issues we developed an empirical solution using a ratio of reflectances that has only two tunable parameters and can be applied to low albedo features the two algorithms the standard linear transform and the new ratio transform were compared through analysis of ikonos satellite imagery against lidar bathymetry the coefficients for the ratio algorithm were tuned manually to a few depths from a nautical chart yet performed as well as the linear algorithm tuned using multiple linear regression against the lidar both algorithms compensate for variable bottom type and albedo sand pavement algae coral and retrieve bathymetry in water depths of less than 10 15 m however the linear transform does not distinguish depths 15 m and is more subject to variability across the studied atolls the ratio transform can in clear water retrieve depths in 25 m of water and shows greater stability between different areas it also performs slightly better in scattering turbidity than the linear transform the ratio algorithm is somewhat noisier and cannot always adequately resolve fine morphology structures smaller than 4 5 pixels in water depths 15 20 m in general the ratio transform is more robust than the linear transform

stratification on the eastern bering sea shelf revisited abstract the timing and magnitude of stratification can have profound influences on the marine ecosystem on the eastern bering sea shelf in the absence of strong wind mixing stratification can be initiated by the melting of seasonal sea ice or by springtime warming of the surface temperature and salinity both influence the stratification of the eastern bering sea shelf with their relative importance varying spatially and temporally in the northern middle shelf domain north of 60 n salinity stratification is often as important as temperature stratification on the southern middle shelf while the influence of temperature on stratification dominates during summer the influence of salinity stratification plays a role in the interannual variability mooring 2 m2 56 9 n 164 1 w has been deployed at 70 m depth in the southern middle shelf domain since 1995 data from this mooring show that stratification typically begins to set up in may and to break down in september october but these dates can vary by 30 d while no trend is found in the timing of the spring setup the fall stratification breakdown exhibited a trend toward later breakdown 2 d later per year from 1996 to 2009 results suggest that it may be difficult to forecast stratification on the eastern bering sea shelf from climate models as simple indices of wind mixing or heat fluxes are not correlated with stratification contrary to intuition the strength of summer stratification is not correlated with depth averaged temperature warm years such as 2000 and 2001 can have low stratification and cold years such as 2007 can have very high stratification this decoupling of stratification and temperature has implications for forecasting the ecosystem in the face of climate change as we cannot assume that projections of a warmer climate simply imply higher stratification in the future

spring and fall phytoplankton blooms in a productive subarctic ecosystem the eastern bering sea during 1995 2011 abstract the timing and magnitude of phytoplankton blooms in subarctic ecosystems often strongly influence the amount of energy that is transferred through subsequent trophic pathways in the eastern bering sea spring bloom timing has been linked to ice retreat timing and production of zooplankton and fish a large part of the eastern bering sea shelf 500 km wide is ice covered during winter and spring four oceanographic moorings have been deployed along the 70 m depth contour of the eastern bering sea shelf with the southern location occupied annually since 1995 the two northern locations since 2004 and the remaining location since 2001 chlorophyll a fluorescence data from the four moorings provide 37 realizations of a spring bloom and 33 realizations of a fall bloom we found that in the eastern bering sea if ice was present after mid march spring bloom timing was related to ice retreat timing p n 11 a fall bloom also commonly occurred usually in late september average day 274 se 4 2 n 33 and its timing was not significantly related to the timing of storms p 0 88 df 1 27 or fall water column overturn p 0 49 df 1 27 the magnitudes of the spring and fall blooms were correlated p 0 011 df 28 the interval between the spring and fall blooms varied between four to six months depending on year and location we present a hypothesis to explain how the large crustacean zooplankton taxa calanus spp likely respond to variation in the interval between blooms spring to fall and fall to spring

soil erosion rates in two karst peak cluster depression basins of northwest guangxi china comparison of the rusle model with 137cs measurements reliable estimation of erosion in karst areas is difficult because of the heterogeneous nature of infiltration and subsurface drainage understanding the processes involved is a key requirement for managing against karst rock desertification this study used the revised universal soil loss equation rusle to estimate the annual soil erosion rates on hillslopes and compared them with cs 137 budget in the depressions at two typical karst peak cluster depression basins in northwest guangxi southwestern china runoff plots data were used to calibrate the slope length factor l of the rusle model by adjusting the accumulated area threshold the rusle model was sensitive to the value of the threshold and required dems with 1 m resolution due to the discontinuous nature of the overland flow the average annual soil erosion rates on hillslopes simulated by the rusle were 0 22 and 0 10 mg ha 1 y 1 2006 through 2011 in the partially cultivated gz1 and the undisturbed gz2 basins respectively the corresponding deposition rates in the depressions agreed well with the cs 137 records when recent changes in precipitation and land use were taken into consideration the study suggests that attention should be given to the rusle l factor when applying the rusle on karst hillslopes because of the discontinuous nature of runoff and significant underground seepage during storm events that effectively reduces the effects of slope length c 2015 elsevier b v all rights reserved

research on soil detachment rate and hydrodynamic parameters of dip anti dip slope in simulated karst trough valley bedding dip has an important influence on soil detachment and flow hydrodynamics in a karst trough valley the laboratory rainfall simulation was conducted with three bedding dips bare slope dip slope and anti dip slope under three rainfall intensities 30 60 90 mm h 1 the characteristics of soil detachment and hydrodynamic parameters were assessed including water flow shear stress stream power unit stream power and unit flow energy the significant effects of bedding dips and rainfall intensities and their interactions on soil detachment and hydrodynamic parameters were examined the results showed that 1 the soil detachment rate decreased with increasing rainfall duration and the soil detachment rate in 30 bedding dip of dip slope was much larger than those in bare slope and anti dip slope in most rainfall intensities 2 the 60 bedding dip of dip slope was the threshold that controlled the stream power unit stream power and unit flow energy increased or decreased under different rainfall intensities and 3 the soil detachment rate had extremely significant positive power relationships with water flow shear stress stream power unit stream power and unit flow energy meanwhile the stream power was the most suitable parameter for predicting soil detachment in a karst trough valley slope therefore these results could provide useful information for soil erosion prediction in a karst trough valley

effects of land use land cover and rainfall regimes on the surface runoff and soil loss on karst slopes in southwest china abstract surface runoff and soil loss from 2007 to 2010 related to land use and rainfall regimes in karst hill slopes in guizhou province southwest china were analyzed using the hierarchical clustering method sixty one rainfall events under the subtropical monsoon climate condition were classified into 5 types of rainfall regimes according to the depth maximum 30 min intensity and duration of rainfall in our study we first demonstrated that the amounts of surface runoff and soil loss on the karst hill slopes were very small compared to the non karst areas because the dual hydrological structure in the karst region including ground and underground drainage systems could influence the processes of rainfall recharge and runoff generation most rainfall water was transported underground through limestone fissures and fractures while little was in the form of surface runoff second the runoff and soil loss were affected by land use management and vegetation cover soil loss was intensified in a descending order to five types of land uses pastureland burned area cropland combination vegetation land young forestland third the runoff and soil loss exhibited remarkable variances among different rainfall regimes large runoff and soil loss were mainly created by heavy rainfall storms with a rainfall depth of more than 40 mm and a maximum 30 min rainfall intensity of over 30 mm h 1 in addition rainfall storms with large antecedent precipitations could also produce large runoff and soil loss these observations indicated that limestone fissures and fractures play important roles in surface runoff generation on karst limestone slopes due to their large storage capacity and high infiltration rate lastly the soil erosion risk in the karst pure limestone slope is quite high and should be paid particular attention especially in regards to over grazing because the soil loss created by a single heavy rainstorm in pastureland was 5 times the annual soil loss tolerance

runoff and erosion processes on bare slopes in the karst rocky desertification area underground pore fissure and bedrock bareness are the main factors that lead to complicated mechanisms of soil erosion in karst regions the objectives of this study were as follows a to measure runoff and sediment generated from the surface and underground in the karst bare slope and b to analyse the impacts of underground pore fissures and bedrock bareness rates on soil erosion to achieve these objectives we designed an experiment in which underground pore fissure degrees and bedrock bareness rates were varied and their impacts on soil erosion were measured the results showed that runoff and sediment yields from the surface and underground increased with increasing rainfall intensity and the surface runoff was much more easily generated when the rainfall intensity was greater ii surface runoff yield first increased and then decreased with increasing bedrock bareness rates while the runoff yield in underground pore fissures increased with increasing bedrock bareness rates thus sediment production on the surface and in underground pore fissures showed the same pattern i e first decreased and then increased iii the surface runoff and sediment generally decreased with increasing degrees of underground pore fissures while that of underground pore fissures presented a different pattern and iv rainfall intensity bedrock bareness rates and underground pore fissure degrees were the important factors affecting soil erosion processes in karst bare slopes because the bedrock bareness rates and underground pore fissure degrees were the main factors causing the uneven distribution of runoff and sediment on soil surfaces and underground therefore soil and water loss in underground pore fissures was the special pattern and main difference in soil erosion processes in the karst region compared with other regions these results have theoretical and practical significance for understanding soil erosion mechanisms and controlling soil and water loss in karst regions

possible refugia for reefs in times of environmental stress this paper investigates the refuge potential of 1 upwelling areas 2 coral areas at medium depth and 3 offshore bank and island reefs in a scenario of increased global warming and thus increased sea surface temperature sst and increased solar uv radiation 1 observations on coral health and water temperature in the subtropical atlantic eleuthera and cat island bahamas and indian ocean sodwana bay south africa suggest a link between cool water delivered by upwelling and coral health after the 1998 bleaching event caused by strong sst anomalies coral health and recovery from the previous year s bleaching was significantly better on the narrow southern cat island shelf 70 of corals healthy where the presence of cold water was observed which was attributed to small scale upwelling than on the wide northern eleuthera shelf 44 of corals healthy where downwelling of hot bank waters was believed to have damaged corals in south africa regular short term upwelling events in five summers reduced sst to well below bleaching level 2 in the northern red sea safaga bay and in south africa sodwana bay wide areas with either coral frameworks or non framework communities exist calculations show that if the top 10 m 20 m of the ocean became inhospitable to corals still 50 4 17 5 of the coral area would remain intact in the red sea and 99 40 in south africa 3 offshore bank and island reefs investigated in the turks caicos and mouchoir banks and grand and little cayman showed high rates of mortality and coral diseases the most remote sites mouchoir bank were not the healthiest refuge areas appear to exist in 1 and 2 but in 3 only if vigorous water circulation is encountered

geomorphic inheritance and the development of tower karst four genetic types of tower karst are identified the most typical consisting of residual hills protruding from a planed carbonate surface veneered by alluvium two extreme possibilities for tower karst evolution are recognized a direct development that is independent of any previous morphology and a sequential development that depends explicitly on the morphological characteristics of a previous cockpit karst phase examples of both are described although the latter appears the more common south china tower karst is examined in this light palaeomagnetic analysis of cave deposits in a tower near guilin indicate the feature to be a time transgressive landform four principal controls of tower development are discussed and a model of tower evolution is presented

carbonate sedimentation on subtropical shelves around lord howe island and balls pyramid southwest pacific abstract lord howe island and balls pyramid are mid oceanic basaltic islands 20 km apart in the tasman sea subaerial carbonates dating back at least 350 ka and a holocene fringing reef occur on lord howe island no reefs or subaerial carbonate deposits occur on balls pyramid both islands sit near the centre of wide shelves that are on average 40 50 m deep with a distinct break of slope between 70 and 100 m depth the lord howe shelf is characterised by a discontinuous drowned ridge which rises to 30 m depth and is located between the mid shelf and shelf edge it is composed of limestone and is interpreted as a fossil reef being veneered by holocene coralline algae early to middle holocene branching coral gravel is found in the lee of the fossil reef indicating limited give up reef growth during the postglacial transgression the surface sediments across the shelf are calcareous except in close proximity to the island where volcanic content is significant coralline algae represent the dominant grain type with minor amounts of coral bryozoans halimeda and foraminifera are common however they are not volumetrically important rhodoliths and molluscs occur near the shelf edge and appear to have accumulated at times of lower sea level these subtropical shelves are mid oceanic examples of the transition between tropical and temperate carbonate sedimentation they indicate the potential for carbonate production on broad planated shelves outside reef forming seas

sea ice and water column structure on the eastern bering sea shelf abstract seasonal sea ice is a defining characteristic of the eastern bering sea shelf and plays a critical role in determining the vertical structure of temperature and salinity over this shelf ice movement relative to local winds ice composition and the impact of both arrival and retreat of ice on the water column at four mooring sites over the middle shelf are examined ice forms primarily in coastal regions and is advected over the southern and outer shelves ice drift from satellite data for two representative years 2003 and 2007 was 2 of local ncep wind speed and oriented 44 to the right of the winds r 2 0 25 measurements from 30 ice cores collected in 2006 2009 gave an average salinity of 5 62 0 88 and an average nitrate concentration of 0 99 0 83 m time series data collected at the biophysical moorings in the bering sea 1995 2012 were used to explore the evolution of the water column under ice at the northern mooring m8 the water column had mixed and cooled to 1 c prior to the arrival of ice little melt occurred after ice arrival at the other three moorings the ocean temperature was 2 4 c when ice arrived resulting in extensive melt melting ice freshened and cooled the upper water column resulting in stratification which persisted for 10 25 days wind induced water column mixing occurred more slowly under the ice than in ice free waters an estimated 1 4 m of ice melted with the first arrival of ice at the three southern moorings where the latent heat of fusion accounted for approximately half the observed cooling during ice retreat there appeared to be little ice melt around the southern two moorings but an estimated 0 8 m at m5 and m8 the extent of ice melt sets up the water column for the following summer

arctic sea ice melt in 2008 and the role of solar heating there has been a marked decline in the summer extent of arctic sea ice over the past few decades data from autonomous ice mass balance buoys can enhance our understanding of this decline these buoys monitor changes in snow deposition and ablation ice growth and ice surface and bottom melt results from the summer of 2008 showed considerable large scale spatial variability in the amount of surface and bottom melt small amounts of melting were observed north of greenland while melting in the southern beaufort sea was quite large comparison of net solar heat input to the ice and heat required for surface ablation showed only modest correlation however there was a strong correlation between solar heat input to the ocean and bottom melting as the ice concentration in the beaufort sea region decreased there was an increase in solar heat to the ocean and an increase in bottom melting

soil structure and nutrient contents in underground fissures in a rock mantled slope in the karst rocky desertification area near surface karst fissures are filled with soils these soils are often derived from the erosion and transport of surface soil but have different properties than the surface soil in karst rocky desertification regions this study was undertaken to determine the soil structure and nutrient contents in underground fissures with different grades of rocky desertification no potential mild moderate and severe based on field surveys near surface karst fissures were selected in a typical karst plateau area soil particle compositions particularly nutrient characteristics were determined through field sampling and laboratory experiments the results indicated that the higher the rock desertification grade was the higher the soil sand 0 02 2 mm content and the lower the clay 0 002 mm content the soil in both limestone and dolomite fissures was basically neutral to weakly alkaline the surface soil in dolomite fissures presented a higher soil organic matter content than that in limestone fissures but the opposite was true for the subsurface soil from the surface to the lower layer the total nitrogen content generally decreased and the total phosphorus content generally decreased in dolomite fissures but exhibited a more complex pattern in limestone fissures the total phosphorus content of the surface soil was higher than that of the subsurface soil but the total potassium content was lower there was no significant difference among different soil layers near surface fissures are a good place to promote vegetation restoration projects because they provide good soil structure and nutritional conditions for plant growth

influence of bare rocks on surrounding soil moisture in the karst rocky desertification regions under drought conditions abstract a large number of bare rocks exposed in the field represent one of the most spectacular scenes of the karst rocky desertification krd process the presence of bare rocks modifies the microenvironment an understanding of soil moisture variability is necessary to characterize the linkages between a region s hydrology ecology and physiography the objective of the study was to determine the influence of those exposed bare rocks on soil moisture in the surrounding area in a typical krd region the forest station of sandoqing in fu yuan county yun nan province southwest china dynamic soil moisture was quantified in feb 2010 during an extreme drought period results showed that during the drought period soil moisture on the north side of the rocks was significantly higher than those on the east west and south sides p

summer plankton production and nutrient consumption patterns in the mertz glacier region of east antarctica abstract we report on a biological and nutrient survey conducted off the eastern adelie and george v coasts of east antarctica in late december 2000 and january 2001 the region was dominated by the mertz glacier tongue mgt and its associated polynya that controlled the amount of open water through the season and influenced stratification near forming and melting ice as in other regions of the southern ocean large concentrations of nitrate phosphate and silicic acid were found chlorophyll levels varied from 0 3 mg m 3 in pack ice and slope regions to greater than 10 mg m 3 in a phaeocystis bloom encountered among grounded ice northeast of the mgt net utilization rates of nutrients were derived from the deficit between measured concentrations and estimated winter values nitrate n n and silicic acid utilization rates ranged from 2 to 12 and 14 to 30 mmol m 2 d 1 respectively and were greatest in commonwealth bay the ratio of nitrate to phosphate utilization was low 10 lower silicic acid to n n ratios were found in regions with substantial populations of phaeocystis sp in the eastern grounded ice region however there was significant variation in the silicic acid to n n utilization that may be induced by mixed layer iron levels that varied from

geometric morphology and soil properties of shallow karst fissures in an area of karst rocky desertification in sw china abstract serious soil erosion and an extremely low rate of soil formation leads to a thin layer of surface soil that makes tree growth difficult in areas of karst meanwhile surface soil driven by runoff enters shallow karst fissures skfs these skfs filled with soil have become the major habitat type in the area here we explore the morphological characteristics of shallow karst fissures as well as the soil physical and chemical properties of the skfs and comprehensively analyse the factors that influence the soil properties three key results are presented first a high heterogeneity of morphological characteristics exists for shallow karst fissures according to the different characteristics of the vertical section the skfs can be divided into 5 types these types are rectangle type pyramid type funnel type net type and diamond type in addition the skf dip angles were mainly between 60 and 90 76 39 the width of the top aperture was mainly between 20 and 40 cm 51 39 and the trace lengths were mainly between 80 and 160 cm 76 39 second compared with their characteristics of surface soil the bulk density and fractal dimension of soil particles of the skfs were both large and the main composition of the skf soil was clay third the soil nutrients of the skfs the organic matter total nitrogen and total phosphorus were lower than the surface soil nutrients but not significantly so the total potassium tk of the skfs was greater than that observed for the surface and increased as the depth of the skf increased the soil nutrients of the skfs were significantly affected by the fissure morphology the poorly connected fissures had better soil fertility when the morphological characteristics and soil properties of the skfs were comprehensively considered the vegetation types that were determined to be the best for use in the ecological restoration of areas of karst rocky desertification were deep rooted plants with especially strong root penetration the result of this study can supply some reference for future studies of karst rocky desertification control and vegetation restoration in the karst area of southwest china in the south claw silicon island in yogyakarta province indonesia and in other karst regions with the same ecological background

effect of microrelief on water erosion and their changes during rainfall soil surface roughness contains two elementary forms depressions and mounds which affect water flow on the surface differently while depressions serve as temporary water storage mounds divert water away from their local summits although roughness impacts on runoff and sediment production have been studied almost no studies have been designed explicitly to quantify the evolution of depressions and mounds and how this impacts runoff generation and sediment delivery the objectives of this study were to analyze how different surface forms affect runoff and sediment delivery and to measure the changes in surface depressions and mounds during rainfall events a smooth surface was used as the control both mounds and depressions delayed the runoff initiating time but to differing degrees and slightly reduced surface runoff when compared to the runoff process from the smooth surface surface mounds significantly increased sediment delivery whilst depressions provided surface storage and hence reduced sediment delivery however as rainfall continued and rainfall intensity increased the depression effect on runoff and erosion gradually decreased and produced even higher sediment delivery than the smooth surface depressions and mounds also impacted the particle size distribution of the discharged sediments many more sand sized particles were transported from the surface with mounds than with depressions the morphology of mounds and depressions changed significantly due to rainfall but to different extents the difference in change had a spatial scale effect i e erosion from each mound contributed to its own morphological change while sediments deposited in a depression came from a runoff contributing area above the depression hence a much greater source area than a single mound the results provide a mechanistic understanding of how soil roughness affects runoff and sediment production copyright 2015 john wiley sons ltd

nutrient and phytoplankton dynamics on the inner shelf of the eastern bering sea the nitrogen cycle on the inner shelf of the southeastern bering sea is complicated due to limited nutrient replenishment across this broad shelf and substantial nitrogen loss through sedimentary processes while diffusion at the inner front may periodically support new production the shelf is generally hypothesized to be a regenerative system this study uses a combination of hydrographic surveys and measurements of nitrogen assimilation and benthic fluxes to examine nitrogen cycling on the inner shelf and connectivity between the middle and inner shelves of the southern and central bering sea results establish the inner shelf as primarily a regenerative system even in spring although new production can occur at the inner front results also identify key processes that influence nutrient supply to the inner shelf and reveal coupling between the middle shelf nutrient pool and production on the inner shelf this article is protected by copyright all rights reserved

the influence of rock resistance on coastal morphology around lord howe island southwest pacific an erratum has been published for this article in earth surface processes and landforms 27 7 2004 931 lord howe island in the northern tasman sea is a remnant of a much larger late miocene basaltic shield volcano much of the island s coastline is exposed to waves that have unlimited fetch but a marked contrast is provided by a fringing coral reef and lagoon that very effectively attenuate wave energy along a portion of the western coastline the geology of the island is varied with hard and resistant basalt lavas breccias and tuffs of intermediate resistance and highly erodible eolianites this variability provides an excellent opportunity to examine the in uence of rock resistance on the development of the spectacular rock coast landforms that occur around the island the hardness of rocks and the extent of weathering around the coastline were assessed using a schmidt hammer and statistical analysis was undertaken to remove outlying values on all but one occasion higher mean rebound values were returned from fresh surfaces than weathered surfaces but only half of these differences were statistically signi cant shore platforms with two distinct levels are juxtaposed along two stretches of coastline and schmidt hammer results lend support to hypotheses that the raised surfaces may be inherited features relative rock resistance was assessed through a combination of schmidt hammer data and measurements of joint density and constrained on the basis of morphological data this approach formed a basis for examining threshold conditions for sea cliff erosion at lord howe island in the context of the distribution of resistant plunging cliffs and erosional shore platforms copyright 2004 john wiley sons ltd

submerged fossil reefs discovered beyond the limit of modern reef growth in the pacific ocean abstract balls pyramid is the southernmost island in a linear island chain in the southwest pacific ocean 24 km south of the limit of known coral reef formation at lord howe island this paper describes the geomorphometric structure of the shelf surrounding balls pyramid through the application of remote sensing data to create a high resolution digital elevation model of the shelf 5 m cell size and seafloor feature classification seafloor features were delineated using the bathymetry model together with slope backscatter and sub bottom profile data the average depth of the 260 6 km2 shelf was 55 m 21 m with the majority of shelf area 77 within 30 60 m water depth dominating the shelf is an extensive mid shelf reef at 30 50 m depth dissected by basin and channel features outer shelf reef and platform features surround the mid shelf with terrace sequences marking the seaward outer shelf rim in 65 100 m depth sub bottom profiles and backscatter data demonstrate substantial accumulation up to 16 5 m of unconsolidated sediments within basin and channel features the submerged mid shelf reefs of balls pyramid are similar to the fossil coral reef system discovered on the lord howe island shelf implying origins as a drowned coral reef system this paper reveals complex shelf topography with extensive submerged reefs on what was previously considered to be a planated volcanic shelf outside of reef forming seas

sea ice impacts on spring bloom dynamics and net primary production in the eastern bering sea 1 in the eastern bering sea changes in sea ice have been implicated in recent major upper trophic level shifts however the underlying relationships between sea ice and primary producers have not been well tested here we combine data from multiple satellite platforms reanalysis model results and biophysical moorings to explore the dynamics of spring and summer primary production in relation to sea ice conditions in the northern bering sea sea ice consistently retreated in late spring leading to ice edge phytoplankton blooms in cold 0 1 c waters however in the southeastern bering sea sea ice retreat was far more irregular although this did not significantly alter bloom timing late retreat led to blooms at the ice edge while early retreat led to blooms in open waters that were warmer 5 4 c and 70 more productive early sea ice retreat also led to higher productivity in summer likely due to weaker thermal stratification overall annual net primary production during warm years of early sea ice retreat was enhanced by 40 50 compared to years with late sea ice retreat in the southeastern bering sea these findings suggest the potential for future sea ice loss to enhance overall carrying capacity of the southeastern bering sea ecosystem consistently warm blooms in the future may also channel more energy flow toward the pelagic rather than benthic environment to date however neither sea ice extent nor the timing of its retreat have undergone long term changes in the eastern bering sea

assessing soil erosion in mediterranean karst landscapes of lebanon using remote sensing and gis abstract maps showing the potential for soil erosion at 1 100 000 scale are produced in a study area within lebanon that can be used for evaluating erosion of mediterranean karstic terrain with two different sets of impact factors built into an erosion model the first set of factors is soil erodibility morphology land cover use and rainfall erosivity the second is obtained by the first adding a fifth factor rock infiltration high infiltration can reflect high recharge therefore decreasing the potential of surface runoff and hence the quantity of transported materials infiltration is derived as a function of lithology lineament density karstification and drainage density all of which can be easily extracted from satellite imagery the influence of these factors is assessed by a weight rate approach sharing similarities between quantitative and qualitative methods and depending on pair wise comparison matrix the main outcome was the production of factorial maps and erosion susceptibility maps scale 1 100 000 spatial and attribute comparison of erosion maps indicates that the model that includes a measure of rock infiltration better represents erosion potential field investigation of rills and gullies shows 87 5 precision of the model with rock infiltration this is 17 5 greater than the precision of the model without rock infiltration these results indicate the necessity and importance of integrating information on infiltration of rock outcrops to assess soil erosion in mediterranean karst landscapes

role of rock dip angle in runoff and soil erosion processes on dip anti dip slopes in a karst trough valley abstract due to the great difficulty of monitoring surface and underground runoff and sediment yield directly the surface and underground hydrological processes associated with soil leakage loss in karst trough valleys remain unknown the objective of this study was to analyse the role of the rock dip angle in the water and soil leakage loss processes to assess the characteristics of surface and underground runoff and soil erosion and to investigate their conversion relationships using rainfall experiments the results showed the following i at a steep rock dip angle 60 the underground runoff yield had a shorter stabilization time than the surface runoff yield and that the underground runoff coefficient of the dip slope exceeded 0 5 ii the surface sediment yield could be divided into the suspended load and the bed load and the underground sediment yield included only the suspended load on the anti dip slope the surface erosion modulus was 0 83 2 50 times the underground erosion modulus iii the surface and underground cumulative runoff was linearly correlated with the cumulative sediment yield the rock dip angle had a significant quadratic relationship with the surface and underground runoff and sediment yield these results improve the understanding of the surface underground runoff and soil erosion processes and have significance for preventing water and soil leakage loss on the slopes of karst trough valleys

holocene lagoonal sedimentation at the latitudinal limits of reef growth lord howe island tasman sea abstract the southernmost limit to coral reef growth occurs on lord howe island 33 30 s 159 05 e where a discontinuous fringing reef flanks the western side of the island coring and radiocarbon dating indicate that carbonate sediments were first deposited within the lagoon around 6500 radiocarbon years bp coincident with sea level reaching close to its modern level high energy conditions dominated the reef with robust branching corals dominating the developing reef growth of the reef crest between 6000 and 5000 yr bp is inferred to have caused a reduction in the energy conditions within the lagoon resulting in mud deposition during this period sedimentation occurred at average rates of around 5 mm yr though locally up to 10 mm yr which infilled almost all the available accommodation space in the lagoon by 4000 yr bp most of the lagoon had accreted to a level very close to the modern lagoon floor having accumulated over 11 m of sediment in the northern part of the lagoon and possibly up to 30 m in the south sediments younger than 3000 yr bp form a thin veneer over these older units with the main deposition being confined to embayments the coastal plain and the infilling of blue hole depressions the reef and lagoon fringing lord howe island appear to have developed their present form primarily during a phase of luxuriant growth in the mid holocene

linkages between sea ice coverage pelagic benthic coupling and the distribution of spectacled eiders observations in march 2008 2009 and 2010 northern bering sea icebreaker based sampling in the northern bering sea south of st lawrence island in march of 2008 2009 and 2010 has provided new data on overall ecosystem function early in the annual productive cycle while water column chlorophyll concentrations 5 m these data together with other physical biological and nutrient data are presented here in conjunction with observed sea ice dynamics and the distribution of an apex predator the spectacled eider somateria fischeri sea ice dynamics in addition to benthic food availability as determined by sedimentation processes play a role in the distribution of spectacled eiders which cannot always access the greatest biomass of their preferred bivalve prey overall the data and observations indicate that the northern bering sea is biologically active in late winter but with strong atmospheric and hydrographic controls these controls pre determine nutrient and chlorophyll distributions water column mixing as well as pelagic benthic coupling

superficial and subterranean soil erosion in tabasco tropical mexico development of a decision tree modeling approach tropical countries suffer from a lack of financial resources to monitor and model sources and outcomes of soil degradation and therefore a scarcity of data in this study it was tried to model superficial and subterranean water erosion based on basic environmental variables such as geological formation soil type or vegetation cover data which are potentially available even in developing countries different forms of water erosion and karst or pseudokarst formations in tabasco southeastern mexico were estimated the study region 3500 km 2 consists of plain and hilly areas with an annual precipitation ranging from 2000 to 4000 mm main land use form is rangeland the area is geologically composed of sedimentary rocks limestone sandstone and conglomerates collecting data by field observations over the entire study area a cartography of different soil loss forms such as rill and gully erosion mass movement sinkholes and tunnels was created including field data from available maps of geological formation soil type precipitation and former land use 20 years ago additionally data collected in the field such as actual land use vegetation cover and inclination were added in the entire study area 1039 sites were affected by soil erosion with 2435 single manifestations of soil erosion 482 sites were found with one gully each 57 sites with erosion rills with a total of 416 392 sites with one mass movement each 85 sites with sinkholes with a total of 1122 and 23 sites with one tunnel each rendzic leptosols over oligocene limestone are strongly affected by sinkholes and tunnels in regions with inclinations of less than 5 this phenomenon is explained by karstic and pseudokarstic formation superficial erosion forms are mainly found on rendzic leptosols over shale sandstone and on eutric or peli eutric vertisols on andesit in areas with inclinations between 5 and 30 the application of classification trees allowed to successfully predict the occurrence of sinkholes and tunnels degree of agreement between prediction and observation very good to excellent even in areas with scarce data bases this could allow for easy identification of high risk areas predictive success of the occurrence of the different forms of superficial soil losses however is low superficial erosion seems to be mainly caused by more specific pedological factors nevertheless automated induction of classification trees can be a valuable tool for preliminary data analysis and hypothesis generation in areas with lack of local expertise and can guide erosion risk mapping and soil conservation planning 2007 elsevier b v all rights reserved

late quaternary structure and development of the northern ningaloo reef australia ningaloo reef situated on the central west coast is australia s largest fringing reef system extending southward from 22 s for over 200 km its narrow lagoon is backed by a coastal plain which is largely composed of an emergent last interglacial reef on the flank of folded tertiary limestones the west facing reef is exposed to strong oceanic swells across a narrow 8 km continental shelf climatic aridity cyclones tsunamis and the poleward flowing leeuwin current all influence the reef system seismic profiling and a coring and dating program along a transect through a reef pass indicate two periods of reef development in the northern part of the reef holocene and last interglacial seaward of the crest the holocene reef forms either a prominent 500 m wide bulge with 10 m of relief and an abrupt seaward slope or a series of discrete patch reefs holocene reef development is limited to depths of less than 30 m and reaches a maximum thickness of ca 10 15 m below the reef crest u th tims dates from distal parts of the last interglacial section between 18 and 36 m give ages toward the end of the high stand 120 115 ka last interglacial reef growth was more extensive of the two filling much of the available accommodation space perhaps as a result of a stronger leeuwin current this substrate subsequently provided an antecedent foundation for holocene reef development

bloom dynamics in early opening waters of the arctic ocean we measured the isotopic composition and accumulation of particulate organic matter pom and the uptake of carbon c and nitrogen n in an early bloom of the most productive recurring polynya of the arctic ocean the estimated compensation irradiance at the onset of the bloom was similar to the average for the north atlantic ocean implying that shallow mixing was of critical importance for the bloom s early initiation planktonic pom had a much lower d 13 c than ice pom suggesting that ice algae contributed little to the pelagic biomass the overall isotopic fractionation of pelagic n during bloom development was consistent with in situ diatom growth under saturating irradiance and limiting no soon after the ice cleared rapid physiological changes induced an order of 2 3 magnitude increase in the c and no uptake capacity of diatoms leading to very high f ratios no uptake total 2 2 3 3 n uptake most of the no taken up appeared in the pom so that little net release of reduced n occurred during 2 3 the period of active growth given the tight coupling between photosynthesis and no uptake under n limitation 2 3 the magnitude of primary production in the arctic ocean is expected to respond to changes in n supply

spatial distribution of rock fragments on steep hillslopes in karst region of northwest guangxi china abstract rock fragments 5 mm in diameter at the soil surface and within the topsoil have a large effect on the intensity of various hydrologic and geomorphic processes however little information is available on the spatial distribution of rock fragments in subtropical regions the objective of this paper was to investigate the relationship between the spatial distribution of rock fragments and landforms on two different steep karst hillslopes in northwest guangxi southwest china on the first hillslope a disintegrated landslide failure with the presence of several large rock outcrops 2 m in height the spatial distribution of rock fragment cover had no obvious relationship with topographic position except that the mean cover percentage of small rock fragments 5 20 mm decreased from bottom to top on the second hillslope an avalanche slope without the presence of large rock outcrops the mean total rock fragment cover 5 600 mm increased from bottom 5 to top 21 with decreasing variability and rock fragments with various sizes 5 20 20 75 and 75 250 mm showed a similar increasing trend the mean total rock fragment cover increased linearly with slope gradient on the second hillslope and tended to increase and then decrease with gradient but their relationship was not obvious on the first hillslope this indicated that the spatial distribution of surface rock fragment cover had a close relationship with the presence of large rock outcrops and slope gradient however the median diameter d50 of the surface rock fragments had an increase decrease trend with slope gradient but there was no obvious relationship on both hillslopes with low overland flow therefore the dominant factor for the spatial distribution of rock fragment cover and size at the soil surface might not be soil erosion by water but slope gradient vegetation and geomorphologic condition of the slope the mean total volumetric rock fragment content 5 250 mm within the topsoil 10 20 cm thick increased linearly from bottom 16 to top 39 with slope gradient on the first hillslope and had a logarithmic increase from bottom 10 to top 27 with gradient on the second hillslope this suggested that rock fragment content within the topsoil was mostly controlled by slope gradient and topographic positions and had not a close relationship with the presence of large rock outcrops

coastal evolution on volcanic oceanic islands a complex interplay between volcanism erosion sedimentation sea level change and biogenic production abstract the growth and decay of oceanic hotspot volcanoes are intrinsically related to a competition between volcanic construction and erosive destruction and coastlines are at the forefront of such confrontation in this paper we review the several mechanisms that interact and contribute to the development of coastlines on oceanic island volcanoes and how these processes evolve throughout the islands lifetime volcanic constructional processes dominate during the emergent island and subaerial shield building stages during the emergent island stage surtseyan activity prevails and hydroclastic and pyroclastic structures form these structures are generally ephemeral because they can be rapidly obliterated by marine erosion with the onset of the subaerial shield building stage coastal evolution is essentially characterized by rapid but intermittent lateral growth through the formation of lava deltas largely expanding the coastlines until they typically reach their maximum extension with the post shield quiescence in volcanic activity destructive processes gradually take over and coastlines retreat adopting a more prominent profile mass wasting and marine and fluvial erosion reshape the landscape and if conditions are favorable biogenic processes assume a prominent role post erosional volcanic activity may temporarily reverse the balance by renewing coastline expansion but islands inexorably enter in a long battle for survival above sea level reef growth and or uplift may also prolong the island s lifetime above the waves the ultimate fate of most islands however is to be drowned through subsidence and or truncation by marine erosion

deglacial mesophotic reef demise on the great barrier reef abstract submerged reefs are important recorders of palaeo environments and sea level change and provide a substrate for modern mesophotic deep water light dependent coral communities mesophotic reefs are rarely if ever described from the fossil record and nothing is known of their long term record on great barrier reef gbr sedimentological and palaeo ecological analyses coupled with 67 14c ams and u th radiometric dates from dredged coral algae and bryozoan specimens recovered from depths of 45 to 130 m reveal two distinct generations of fossil mesophotic coral community development on the submerged shelf edge reefs of the gbr they occurred from 13 to 10 ka and 8 ka to present we identified eleven sedimentary facies representing both autochthonous in situ and allochthonous detrital genesis and their palaeo environmental settings have been interpreted based on their sedimentological characteristics biological assemblages and the distribution of similar modern biota within the dredges facies on the shelf edge represent deep sedimentary environments primarily forereef slope and open platform settings in palaeo water depths of 45 95 m two coral algal assemblages and one non coral encruster assemblage were identified 1 massive and tabular corals including porites montipora and faviids associated with lithophylloids and minor mastophoroids 2 platy and encrusting corals including porites montipora and pachyseris associated with melobesioids and sporolithon and 3 melobesiods and sporolithon with acervulinids foraminifera and bryozoans based on their modern occurrence on the gbr and coral sea and modern specimens collected in dredges these are interpreted as representing palaeo water depths of 100 m respectively the first mesophotic generation developed at modern depths of 85 130 m from 13 to 10 2 ka and exhibit a deepening succession of 100 m palaeo water depth through time the second generation developed at depths of 45 70 m on the shelf edge from 7 8 ka to present and exhibit stable environmental conditions through time the apparent hiatus that interrupted the mesophotic coral communities coincided with the timing of modern reef initiation on the gbr as well as a wide spread flux of siliciclastic sediments from the shelf to the basin for the first time we have observed the response of mesophotic reef communities to millennial scale environmental perturbations within the context of global sea level rise and environmental changes

a numerical model of mesoscale physical biological interactions in the fram strait marginal ice zone a numerical model of marginal ice zones is presented which includes ice atmosphere ocean interactions and couples biological processes to the physical dynamics of the ice edge we have used initial conditions from the fram strait in spring when stratification is increasing nutrient concentrations are high and solar radiation is increasing conditions which are found prior to an ice edge phytoplankton bloom we present three sets of experiments 1 a standard case and variations resulting from different initial conditions with oceanic and ice melt stratification but no winds or eddies 2 one with wind forcing and ice cover but no eddies and 3 cases with cyclonic and anticyclonic eddies under ice cover in general stratification within the upper layers accelerates the growth and accumulation of phytoplankton when the stratification is due to ice melt only the bloom is horizontally constrained between the ice and the ice edge frontal structure maximum primary productivity occurs 7 to 10 days after the introduction of stratification and chlorophyll reaches a maximum approximately 3 days later the bloom s biomass is eventually limited by nutrients wind driven ice edge upwelling alone was ineffective in stimulating phytoplankton growth however any wind induced horizontal movement of ice either uncovers nutrient rich water or advects nutrients into open water which stimulates phytoplankton growth when a cyclonic eddy rotates under the ice a surface divergence results causing the ice to open in the center while upwelling at the eddy core injects nutrients into the euphotic zone anticyclonic eddies induce downwelling at the eddy s core and upwelling and surface divergence at the outer edges with the increased irradiance and high nutrient concentrations phytoplankton biomass within the eddy increases rapidly

diversity and endemism of the benthic seamount fauna in the southwest pacific seamounts comprise a unique deep sea environment characterized by substantially enhanced currents and a fauna that is dominated by suspension feeders such as corals1 2 3 4 the potential importance of these steep sided undersea mountains which are generally of volcanic origin to ocean biogeography and diversity was recognized over 40 years ago5 but this environment has remained very poorly explored a review3 of seamount biota and biogeography reported a total of 597 invertebrate species recorded from seamounts worldwide since the challenger expedition of 1872 most reports based on a single taxonomic group were extremely limited 5 seamounts of the estimated more than 30 000 seamounts in the world s oceans4 6 accounted for 72 of the species recorded only 15 of the species occurring on seamounts were considered potential seamount endemics here we report the discovery of more than 850 macro and megafaunal species from seamounts in the tasman sea and southeast coral sea of which 29 34 are new to science and potential seamount endemics low species overlap between seamounts in different portions of the region indicates that the seamounts in clusters or along ridge systems function as island groups or chains leading to highly localized species distributions and apparent speciation between groups or ridge systems that is exceptional for the deep sea these results have substantial implications for the conservation of this fauna which is threatened by fishing activity7

the relationship between sea ice break up water mass variation chlorophyll biomass and sedimentation in the northern bering sea the northern bering sea shelf is dominated by soft bottom infauna and ecologically significant epifauna that are matched by few other marine ecosystems in biomass the likely basis for this high benthic biomass is the intense spring bloom but few studies have followed the direct sedimentation of organic material during the bloom peak in may satellite imagery water column chlorophyll concentrations and surface sediment chlorophyll inventories were used to document the dynamics of sedimentation to the sea floor in both 2006 and 2007 as well as to compare to existing data from the spring bloom in 1994 an atmospherically derived radionuclide 7be that is deposited in surface sediments as ice cover retreats was used to supplement these observations as were studies of light penetration and nutrient depletion in the water column as the bloom progressed chlorophyll biomass as sea ice melted differed significantly among the three years studied 1994 2006 2007 the lowest chlorophyll biomass was observed in 2006 after strong northerly and easterly winds had distributed relatively low nutrient water from near the alaskan coast westward across the shelf prior to ice retreat by contrast in 1994 and 2007 northerly winds had less northeasterly vectors prior to sea ice retreat which reduced the westward extent of low nutrient waters across the shelf additional possible impacts on chlorophyll biomass include the timing of sea ice retreat in 1994 and 2007 which occurred several weeks earlier than in 2006 in waters with the highest nutrient content late winter brine formation and associated water column mixing may also have impacts on productivity that have not been previously recognized these observations suggest that interconnected complexities will prevent straightforward predictions of the influence of earlier ice retreat in the northern bering sea upon water column productivity and any resulting benthic ecosystem re structuring as seasonal sea ice retreats in the northern bering sea