Departmental Papers (EES) Copyright (c) 2013 University of Pennsylvania All rights reserved. http://repository.upenn.edu/ees_papers Recent documents in Departmental Papers (EES) en-us Wed, 23 Jan 2013 20:10:53 PST 3600 Comparison of Measured and Modeled Temporal Coherence of Sound Near 75 Hz and 3683 km in the Pacific Ocean http://repository.upenn.edu/ees_papers/58 http://repository.upenn.edu/ees_papers/58 Tue, 11 Jan 2011 12:56:59 PST The hypothesis to test is internal gravity waves following a Garrett–Munk spectrum are sufficient to explain temporal coherence of sound at 3683 km in the Pacific Ocean for a signal at 75 Hz and a pulse resolution of 0.03 s. Signals from a 20 min transmission are collected on a towed array. After correcting the data for what likely appears to be acceleration of the receiver, the probability distribution for multipath coherence time is very similar to that obtained from Monte Carlo simulations of the impulse response. The most likely coherence time is 20 min, the longest that can be measured with a 20 min transmission. Predictions of multipath temporal coherence and amplitude fluctuations appear accurate enough to make useful predictions of channel capacity.

]]> John L. Spiesberger Temporal and spatial coherence of sound at 250 Hz and 1659 km in the Pacific Ocean: Demonstrating internal waves and deterministic effects explain observations http://repository.upenn.edu/ees_papers/56 http://repository.upenn.edu/ees_papers/56 Wed, 22 Dec 2010 07:40:34 PST The hypothesis tested is that internal gravity waves explain temporal and spatial coherences of sound at 1659 km in the Pacific Ocean for a signal at 250 Hz and a pulse resolution of 0.02 s. From data collected with a towed array, the measured probability that coherence time is 1.8 min or longer is 0.8. Using a parabolic approximation for the acoustic wave equation with sound speeds fluctuating from internal waves, a Monte-Carlo model yields coherence time of 1.8 min or more with probability of 0.9. For spatial coherence, two subsections of the array are compared that are separated by 142 and 370 m in directions perpendicular and parallel to the geodesic, respectively. Measured coherence is 0.54. This is statistically consistent with the modeled 95% confidence interval of [0.52, 0.76]. The difference of 370 m parallel to the section causes spatial coherence to degrade deterministically by a larger amount than the effect of internal waves acting on the 142 m separation perpendicular to the section. The models are run without any tuning with data.

]]> John L. Speisberger Helping HELP with limited resources: The Luquillo experience http://repository.upenn.edu/ees_papers/55 http://repository.upenn.edu/ees_papers/55 Thu, 03 Sep 2009 08:41:50 PDT By definition the HELP approach involves the active participation of individuals from a wide range of disciplines and backgrounds, including representatives of industry, academics, natural resource managers, and local officials and community leaders. While there is considerable enthusiasm and support for the integrated HELP approach, a central problem for all HELP basins is how to effectively engage individuals and groups with few, if any financial resources. In the Luquillo HELP project we have managed this issue by focusing our efforts on holding small, public meetings and workshops with technocrats and managers who are engaged in local water resource management. To date several forums have been organised, including: technical meetings with the directors of natural resource agencies; presentations and panel discussions at the meetings of local professional societies, including the societies of Civil Engineers and Architects, the Commonwealth Association of Tourism, the Association of Builders and Developers, and the Puerto Rican Association of Lawyers. During these forums HELP specialists gave presentations and led discussions on how integrated watershed management can help resolve local problems. Because the audience are directly involved with these issues, they are quite responsive to these discussions and have often provided unique solutions to common problems. Technical workshops are co-sponsored by local municipalities – these day-long workshops are hosted by a municipality and include managers from other municipalities, the local water authority, and local community leaders. Additional activities include: technical advice on water infrastructure projects is given; there are educational exchanges between local and international students, scientists, natural resource managers, and community leaders; and synthesis publications relevant to integrated water resource management are produced. Other activities have included compiling oral environmental histories and organising watershed restoration activities. This paper describes these activities and discusses the benefits and costs of each approach.

]]> Frederick N. Scatena et al. <em>Marattia aganzhenensis</em> sp. nov from the Lower Jurassic Daxigou Formation of Lanzhou, Gansu, China http://repository.upenn.edu/ees_papers/54 http://repository.upenn.edu/ees_papers/54 Wed, 19 Mar 2008 07:02:11 PDT Marattia aganzhenensis sp. nov. from the Lower Jurassic Daxigou Formation of Lanzhou, Gansu, China, is the second species of Marattia known in fertile structure from China, in addition to Marattia asiatica. The new species demonstrates the variability of the genus through its distinct character states. This new species is distinguished by the absence of venuli recurrentes, the shorter synangia, exclusively monolete spores without surface ornamentation, and the low number of spores produced per sporangium.

]]> Shu Yang et al. Late Quaternary Relative Sea-level Changes in Mid-latitudes http://repository.upenn.edu/ees_papers/52 http://repository.upenn.edu/ees_papers/52 Thu, 07 Jun 2007 07:38:42 PDT High quality relative sea-level (RSL) data from mid-latitude regions reveal spatial and temporal variations among eustatic, isostatic (glacio and hydro) and local factors since the Last Glacial Maximum. In regions of the Atlantic seaboard of North America and Europe that were once covered by the major ice sheets RSL fell by over 100m because of isostatic rebound. In contrast, the regions at the periphery and beyond of the ice sheets observations showed continually rising sea levels, at variable rates, due to the interplay between post-glacial isostatic recovery, marginal forebulge collapse and hydro-isostatic loading. The RSL observations from the Southern Hemisphere illustrated a mid-Holocene highstand of various magnitudes and timing.

]]> Benjamin P. Horton Early Permian coal-forming floras preserved as compressions from the Wuda District (Inner Mongolia, China) http://repository.upenn.edu/ees_papers/51 http://repository.upenn.edu/ees_papers/51 Tue, 08 May 2007 08:20:16 PDT Four different compression/impression floras are preserved in only 4.32 m of the geologic section in the Early Permian Shanxi Formation of the Wuda District of Inner Mongolia, northwestern China. These floras represent four different plant communities and landscapes that followed each other in time. The oldest flora was rooted in sandy clay and initiated peat accumulation that lead to the formation of the lower coal seam. This seam is 230-cm thick and overlain by a 66-cm thick volcanic tuff that preserves a second different flora that grew on the peat at the time of the ash-fall. Standing stems and large plant parts are present. The upper part of the tuff is rooted by a single species of lycopsid (the third flora) again initiating peat accumulation. On top of this second seam of 120 cm thickness rests a roof-shale, deposited as mud in a shallow lake, the formation of which was responsible for the cessation of peat deposition. This fourth flora represents the plants growing around the lake on clastic substrate. Four different environments followed each other in this locality over a geologically short time span and each time conditions prevailed to preserve plant macrofossils. Three of these floras represent peat-forming plant communities of essentially the same time interval. This demonstrates the great variability of vegetation and landscapes in the tropical Cathaysian realm of the Late Paleozoic.

]]> Hermann W. Pfefferkorn et al. Quantifying Holocene Sea Level Change Using Intertidal Foraminifera: Lessons from the British Isles http://repository.upenn.edu/ees_papers/50 http://repository.upenn.edu/ees_papers/50 Mon, 02 Apr 2007 12:43:28 PDT Salt-marsh foraminifera have been used to reconstruct Holocene sea-level changes from coastlines around the world. In this work, we compile the results of surface foraminiferal surveys from fifteen study sites located on the east, south and west coasts of Great Britain, and the west coast of Ireland. These data, which comprise 236 samples and 84 species, are used to summarize the contemporary distributions of intertidal foraminifera around the British Isles, and to examine the environmental controls governing them.

Seasonal and sub-surface foraminiferal data suggest that foraminiferal dead assemblages provide the most appropriate dataset for studying patterns of foraminiferal distributions in the context of sea-level reconstruction. In contrast to live populations or total assemblages, the dead assemblages are less affected by seasonal fluctuations and post-depositional modifications. Sub-surface foraminiferal data also indicate that foraminifera at the study sites live primarily in epifaunal habitats. Consequently, foraminiferal samples comprising the upper centimeter of sediment are appropriate analogues for the study of past sea-level change employing fossil assemblages contained within intertidal deposits.

Surface dead assemblages from the fifteen study sites indicate a vertical zonation of foraminifera within British and Irish salt-marshes that is similar to those in other mid-latitude, cool temperate intertidal environments. Whilst the composition and vertical ranges of assemblage zones vary between sites, two general sub-divisions can be made: an agglutinated assemblage restricted to the vegetated marsh; and a high diversity calcareous assemblage that occupies the mudflats and sandflats of the intertidal zone. Three of the fifteen study sites permit further subdivision of the agglutinated assemblage into a high and middle marsh zone (Ia) dominated by Jadammina macrescens with differing abundances of Trochammina inflate and Miliammina fusca, and a low marsh zone (Ib) dominated by M. fusca. The calcareous assemblage is commonly comprised of Ammonia spp., Elphidium williamsoni and Haynesina germanica, in association with a wide range of minor taxa.

The vertical zonations of the study areas suggest that the distribution of foraminifera in the intertidal zone is usually a direct function of elevation relative to the tidal frame, with the duration and frequency of intertidal exposure as the most important controlling factors. This relationship is supported by canonical correspondence analyses of the foraminiferal data and a series of environmental variables (elevation, pH, salinity, substrate and vegetation cover).

These modern foraminiferal data are used to develop predictive transfer functions capable of inferring the past elevation of a sediment sample relative to the tidal frame from its fossil foraminiferal content. The results indicate that transfer functions perform most reliably when they are based on modern data collected from a wide range of intertidal environments. The careful combination of foraminiferal estimates of paleomarshsurface elevation with detailed lithostratigraphy and chronostratigraphy can produce high-resolution records of relative sea-level change with sufficient resolution to detect low-magnitude variability but long enough duration to reliably establish climate-ocean relationships and secular trends. Thus, the transfer function approach has the potential to link short-term instrumental and satellite records with established longer-term geologically based reconstructions of relative sea level.

]]> Benjamin P. Horton et al. The Development Of A Modern Foraminiferal Data Set For Sea-Level Reconstructions, Wakatobi Marine National Park, Southeast Sulawesi, Indonesia http://repository.upenn.edu/ees_papers/49 http://repository.upenn.edu/ees_papers/49 Mon, 04 Dec 2006 10:41:23 PST We collected modern foraminiferal samples to characterize the foraminiferal environments and investigate the role that temporal and spatial variability may play in controlling the nature and significance of foraminiferal assemblages of the mangroves of Kaledupa, Wakatobi Marine National Park, Southeast Sulawesi, Indonesia. The study of foraminiferal live and dead assemblages indicates that dead assemblages are least prone to vary in time and space, and furthermore, they accurately represent the subsurface assemblages that are the focus of paleoenvironmental reconstructions.

Further analyses of the dead assemblages indicate a vertical zonation of foraminifera within the intertidal zone. Zone D-Ia is dominated by agglutinated foraminifera Arenoparrella mexicana, Miliammina fusca, M. obliqua and Trochammina inflata. Zone D-Ib has mixed agglutinated/calcareous assemblages with species such as T. inflata and Ammonia tepida. Zone D-II is dominated by numerous calcareous species including A. tepida, Discorbinella bertheloti, Elphidium advenum and Quinqueloculina spp. Zone D-Ia is found to be the most accurate sea-level indicator and its assemblages are omnipresent world-wide. Zones D-Ib and D-II are subject to both spatial and temporal variations which must be included in any sea-level reconstructions.

]]> Benjamin P. Horton et al. Infaunal Marsh Foraminifera From the Outer Banks, North Carolina, USA http://repository.upenn.edu/ees_papers/48 http://repository.upenn.edu/ees_papers/48 Mon, 04 Dec 2006 06:37:52 PST The distribution and abundance of live (rose Bengal stained) and dead, shallow infaunal (0–1 cm depth) and deep infaunal (>1 cm depth) benthic foraminifera have been documented at three locations representing different salinity settings on the fringing marshes along the Pamlico Sound and Currituck Sound coasts of North Carolina’s Outer Banks. Two cores taken at each site represent the lower and higher marsh.

Twenty-two taxa were recorded as live. Of these, eight taxa were found only at shallow infaunal depths; the other 14 taxa occur at deep infaunal depths in one or more cores. Only Jadammina macrescens and Tiphotrocha comprimata were recorded as living in all six cores. The distributions of the other taxa were restricted by combinations of infaunal depth, salinity regime and location on the marsh.

The tests of infaunal foraminifera were generally more likely to be preserved in the lower marsh than the higher marsh at low- and intermediate-salinity sites. The opposite pattern was evident at the high-salinity site but this may be due to the low numbers of deep infaunal specimens recovered. Arenoparrella mexicana, Haplophragmoides wilberti, Jadammina macrescens and Trochammina inflata are the most resistant taxa, whereas Miliammina fusca is the species whose tests are most likely to be lost to post-mortem degradation. In five of the six cores, foraminiferal assemblages and populations do not differ significantly with depth which suggests that the foraminifera of the 0–1 cm depth interval provide an adequate model upon which paleoenvironmental (including former sea level) reconstructions can be based.

]]> Stephen J. Culver et al. Intertidal Mangrove Foraminifera From The Central Great Barrier Reef Shelf, Australia: Implications for Sea-Level Reconstruction http://repository.upenn.edu/ees_papers/47 http://repository.upenn.edu/ees_papers/47 Fri, 01 Dec 2006 13:15:33 PST Contemporary foraminiferal samples and environmental information were collected from three fringing mangrove environments (Sandfly Creek Transect 1 and 2, and Cocoa Creek) in Cleveland Bay, and an estuarine mangrove environment (Saunders Creek) in Halifax Bay, on the central Great Barrier Reef (GBR) coastline, Australia, to elucidate the relationship of the foraminiferal assemblages with the environment. The data support the vertical zonation concept, which suggests that the distribution of foraminifera in the intertidal zone is usually a direct function of elevation, with the duration and frequency of subaerial exposure as the most important factor. An agglutinated foraminiferal assemblage dominated by Miliammina fusca, Trochammina inflata, Ammotium directum and Haplophragmoides sp. exists at the landward edge of the field sites, in a zone between just above Mean Low Water of Neap Tides to Highest Astronomical Tide level (a vertical range of 1.8 m). In addition, a foraminiferal assemblage dominated by Ammonia aoteana is found at all sites, existing between just below Mean Low Water of Neap Tides and Mean High Water of Neap Tides (a vertical range of 0.8 m). These assemblages may be used to reconstruct sea level from fossil cores from the area.

]]> Sarah A. Woodroffe et al. Modern saltmarsh diatom distributions of the Outer Banks, North Carolina, and the development of a transfer function for high resolution reconstructions of sea level http://repository.upenn.edu/ees_papers/46 http://repository.upenn.edu/ees_papers/46 Wed, 29 Nov 2006 13:42:26 PST We collected modern diatom samples from Currituck Barrier Island, Oregon Inlet and Pea Island marshes, Outer Banks, North Carolina, USA, which have different salinity regimes due to their varying distances from a major barrier island inlet. Multivariate analyses separate the saltmarsh diatom assemblages into distinct elevational zones, dominated by differing abundances of polyhalobous, mesohalobous and oligohalobous taxa, suggesting that the distribution of saltmarsh diatoms is a direct function of elevation, with the most important controlling factors being the duration and frequency of subaerial exposure.

We developed the first diatom-based transfer function for the east coast of North America to reconstruct former sea levels based upon the relationship between diatom assemblage and elevation. Results imply that this is possible to a precision of ±0.08 m, superior to most similar studies from temperate, mid-latitude environments. The transfer function is used to construct a relative sea-level curve from fossil assemblages from Salvo, North Carolina. These results suggest a sea-level rise of 0.7 m over the last c. 150 years, at an average of c. 3.7 mm year−1. This is consistent with existing sea-level data, and illustrates the utility of the transfer function approach.

]]> Benjamin P. Horton et al. Regions that influence acoustic propagation in the sea at moderate frequencies, and the consequent departures from the ray-acoustic description http://repository.upenn.edu/ees_papers/45 http://repository.upenn.edu/ees_papers/45 Wed, 29 Nov 2006 13:22:12 PST In the limit where a transient signal is comprised of very large frequencies, spatial regions within an inhomogeneous medium that influence the propagation from a source to a receiver lie along one or more ray paths. At lower frequencies for which the geometrical acoustic approximation is of borderline applicability, the regions that influence such transient signals are extended because of diffraction. Previous research has addressed the numerical determination of those spatial regions that influence propagation at low frequency. The present paper addresses the question of how high the center frequency need be so that the regions of influence are nearly described as ray paths for a model ocean in which the speed of sound increases nearly linearly with depth from a perfectly reflecting surface. Computations indicate that near 2500 Hz and at a range of 50 km, the region of influence resembles a ray. Noticeable departures from the ray picture are found at a range of 500 km. Various physical and mathematical causes for the departures from the ray propagation model for lower frequencies and for greater ranges are identified and discussed.

]]> John L. Spiesberger Effects of Nutrient Availability and Other Elevational Changes on Bromeliad Populations and Their Invertebrate Communities in a Humid Tropical Forest in Puerto Rico http://repository.upenn.edu/ees_papers/44 http://repository.upenn.edu/ees_papers/44 Fri, 23 Jun 2006 17:31:00 PDT Nutrient inputs into tank bromeliads were studied in relation to growth and productivity, and the abundance, diversity and biomass of their animal inhabitants, in three forest types along an elevational gradient. Concentrations of phosphorus, potassium and calcium in canopy-derived debris, and nitrogen and phosphorus in phytotelm water, declined with increasing elevation. Dwarf forest bromeliads contained the smallest amounts of debris/plant and lowest concentrations of nutrients in plant tissue. Their leaf turnover rate and productivity were highest and, because of high plant density, they comprised 12.8and contained 3.3 t ha -1 of water. Annual nutrient budgets indicated that these microcosms were nutrient-abundant and accumulated < 5dwarf forest, where accumulation was c. 25biomass/plant peaked in the intermediate elevation forest, and were positively correlated with the debris content/bromeliad across all forest types. Animal species richness showed a significant mid-elevational peak, whereas abundance was independent of species richness and debris quantities, and declined with elevation as forest net primary productivity declined. The unimodal pattern of species richness was not correlated with nutrient concentrations, and relationships among faunal abundance, species richness, nutrient inputs and environment are too complex to warrant simple generalizations about nutrient resources and diversity, even in apparently simple microhabitats.

]]> Barbara A. Richardson et al. Non-Indigenous Bamboo along Headwater Streams of the Luquillo Mountains, Puerto Rico: Leaf Fall, Aquatic Leaf Decay and Patterns of Invasion http://repository.upenn.edu/ees_papers/43 http://repository.upenn.edu/ees_papers/43 Fri, 23 Jun 2006 17:19:42 PDT The introduction of bamboo to montane rain forests of the Luquillo Mountains, Puerto Rico in the 1930s and 1940s has led to present-day bamboo monocultures in numerous riparian areas. When a non-native species invades a riparian ecosystem, in-stream detritivores can be affected. Bamboo dynamics expected to influence stream communities in the Luquillo Experimental Forest (LEF) were examined. Based on current distributions, bamboo has spread downstream at a rate of 8 m y -1 . Mean growth rate of bamboo culms was 15.3 cm d -1 . Leaf fall from bamboo stands exceeded that of native mixed-species forest by c. 30(k = -0.021), and leaves from another abundant riparian exotic, Syzygium jambos (Myrtaceae) (k = -0.018), decayed at relatively slow rates when submerged in streams in fine-mesh bags which excluded macro-invertebrate leaf processors. In a second study, with leaf processors present, bamboo decay rates remained unchanged (k = -0.021), while decay rates of S. jambos increased (k = -0.037). Elemental losses from bamboo leaves in streams were rapid, further suggesting a change in riparian zone/stream dynamics following bamboo invasion. As non-indigenous bamboos spread along Puerto Rico streams, they are likely to alter aquatic communities dependent on leaf input.

]]> Paul J. O'Connor et al. Effects of Hurricane Disturbance on Stream Water Concentrations and Fluxes in Eight Tropical Forest Watersheds of the Luquillo Experimental Forest, Puerto Rico http://repository.upenn.edu/ees_papers/42 http://repository.upenn.edu/ees_papers/42 Fri, 23 Jun 2006 16:18:29 PDT Stream water chemistry responds substantially to watershed disturbances, but hurricane effects have not been extensively investigated in tropical regions. This study presents a long-term (2.5-11 y) weekly record of stream water chemistry on eight forested watersheds (catchment basins) in the Luquillo Mountains of Puerto Rico. This includes a period before and at least 2 y after the disturbance caused by the 1989 Hurricane Hugo. Nitrate, potassium and ammonium concentrations increased after the hurricane and remained elevated for up to 2 y. Sulphate, chloride, sodium, magnesium and calcium showed smaller relative significant changes. Average stream water exports of potassium, nitrate and ammonium increased by 13.1, 3.6 and 0.54 kg ha -1 y -1 in the first post-hurricane year across all watersheds. These represent increases of 119, 182 and 102 of record. The increased stream outputs of potassium and nitrogen in the first 2 y post-hurricane are equivalent to 3of the hurricane-derived plant litter. Effects of hurricanes on tropical stream water potassium and nitrogen can be greater than those caused by canopy gaps or limited forest cutting, but less than those following large-scale deforestation or fire.

]]> Douglas A. Schaefer et al. The development and application of a diatom-based quantitative reconstruction technique in forensic science http://repository.upenn.edu/ees_papers/41 http://repository.upenn.edu/ees_papers/41 Fri, 23 Jun 2006 13:34:49 PDT Diatoms are a group of unicellular algae that have been recorded and classified for over 200 years and have been used in a range of applications in forensic science. We have developed a quantitative diatom-based reconstruction technique to confirm drowning as a cause of death and localize the site of drowning in two recent, high-profile, case studies. In both case studies we collected diatom samples from the local and/or regional area to act as a control in the examination of diatom assemblages associated with lungs and clothing. In Case Study 1 the modern analog technique suggested that all lung and clothing samples have statistically significant similarities to control samples from shallow water habitats. In Case Study 2, the analog matching suggested that the majority of lung samples show a statistically significant relationship to samples from a pond, indicating that this was the drowning medium.

]]> Benjamin P. Horton et al. The development of a diatom-based transfer function along the Pacific coast of eastern Hokkaido, northern Japan—an aid in paleoseismic studies of the Kuril subduction zone http://repository.upenn.edu/ees_papers/40 http://repository.upenn.edu/ees_papers/40 Thu, 22 Jun 2006 14:37:00 PDT This paper provides a dataset to develop a diatom-based transfer function, which is applicable to paleoseismic studies at southwestern Kuril subduction zone, northern Japan. Modern diatom samples were collected from five transects from saltmarshes of Lakes Akkeshi and Onnetoh along the Pacific coast of eastern Hokkaido. The relationships between diatom species and environmental variables were elucidated by canonical correspondence analysis (CCA) and partial CCAs. Partial CCAs associated with Monte Carlo permutation tests show that elevation accounts for a significant portion of the total variance in the diatom data. Therefore, statistically significant transfer functions quantifying the relationship between modern diatom assemblages and elevation were developed using weighted averaging partial least squares and applied to fossil diatom assemblages from Lake Onnetoh. The reconstructed curve of elevations contains five emergence and four submergence events and the transfer functions calculated the amplitude of four of the emergence events to be at least 1 m. The results are consistent with paleoecological data produced by previous studies. If these events represent uplift associated with interplate earthquake and subsidence during an interseismic period along the Kuril subduction zone, transfer functions of eastern Hokkaido can contribute to reconstruction of the recurrence intervals and the amplitude of earthquakes.

]]> Yuki Sawai et al. The application of local and regional transfer functions to the reconstruction of Holocene sea levels, north Norfolk, England http://repository.upenn.edu/ees_papers/39 http://repository.upenn.edu/ees_papers/39 Thu, 01 Jun 2006 14:16:24 PDT Foraminiferal assemblages from Thornham and Brancaster marshes (Norfolk, UK) illustrate statistically significant relationship with elevation with respect to the tidal frame. We develop local (data from Thornham and Brancaster marshes) and regional (data from Thornham and Brancaster marshes combined with those from 11 other sites around the UK) predictive foraminifera-based transfer functions to reconstruct former sea levels from a Holocene sediment sequence from Holkham, north Norfolk, UK. The two transfer functions produce similar patterns of tidal elevation change during the Holocene. The vertical error ranges of the local transfer function are smaller than those of the regional transfer function, although the difference (0.09 m) is not significant when compared to other factors affecting the reconstructed elevation. The value of the reconstructed elevations also differ between the two transfer functions (by up to 0.43 m), and this is primarily due to the lack of modern analogues in the local transfer function. We conclude that the reconstructions derived from the regional transfer function are more reliable than those of the local transfer function, since the latter achieves its slight increase in precision at the expense of a significant decrease in predictive power. The regional transfer function is used to construct a relative sea-level curve from fossil assemblages within a sediment core from north Norfolk, UK. These results are consistent with existing sea-level data and geophysical model predictions, and illustrate the utility of the foraminifera-based transfer function approach.

]]> Benjamin P. Horton et al. Holocene sea levels and palaeoenvironments, Malay-Thai Peninsula, southeast Asia http://repository.upenn.edu/ees_papers/38 http://repository.upenn.edu/ees_papers/38 Thu, 01 Jun 2006 14:12:36 PDT Sedimentological and palynological investigations of Great Songkhla Lakes, east coast of the Malay-Thai Peninsula, Southeast Asia, reveal sedimentary sequences rich in palynomorph assemblages dominated by pollen of mangroves and freshwater swamps. Compared with other regions in Southeast Asia the assemblages are of relatively low diversity. Geochronological data indicate that the Great Songkhla Lakes record one of the earliest mangrove environments in Southeast Asia (8420–8190 cal. yr BP), which are subsequently replaced by a freshwater swamp at 7880–7680 cal. yr BP owing to the decline of marine influence. Sea-level observations from Great Songkhla Lakes and other areas of the Malay-Thai Peninsula reveal an upward trend of Holocene relative sea level from a minimum of − 22 m at 9700–9250 cal. yr BP to a mid-Holocene high stand of 4850–4450 cal. yr BP, which equates to a rise of c. 5.5 mm/yr. The sea-level fall from the high stand is steady at c. − 1.1 mm/yr. Geophysical modelling shows that hydroisostasy contributes a significant spatial variation to the sea-level signal between some site locations (3–4 m during the mid-Holocene), indicating that it is not correct to construct a single relative sea-level history for the Malay-Thai Peninsula.

]]> Benjamin P. Horton et al. Patterns in cumulative increase in live and dead species from foraminiferal time series of Cowpen Marsh, Tees Estuary, UK: Implications for sea-level studies http://repository.upenn.edu/ees_papers/37 http://repository.upenn.edu/ees_papers/37 Thu, 01 Jun 2006 11:09:01 PDT We have collected live and dead foraminiferal times-series data at 2-weekly intervals for a 12-month period from the intertidal zone of Cowpen Marsh, Tees Estuary, UK. The data from the 689 samples show profound differences between live and dead assemblages, although assemblages are dominated by just three species, Haynesina germanica, Jadammina macrescens and Trochammina inflata, which represent over 70% of the assemblage. The cumulative increase in species of most environments approximates to a lognormal or log series. None of the datasets show a broken stick pattern. The cumulative maximum number of species, which represents the species carrying capacity of the environment, is recorded earlier in the life assemblages than the dead counterparts. The dead assemblage of Cowpen Marsh is found to have a higher abundance (435 compared to 163 individuals/10 cm3) and number of species (52 compared to 28) than its live counterpart because the dead assemblage represents many generations added over a long period of time. In contrast, some species are recorded in the live dataset that were not found in the dead assemblage, indicating the dead record is either incomplete (e.g. taphonomic change) or inadequately sampled.

We investigated the influence of patterns in cumulative increase on dead assemblages for sea-level reconstructions through the development of foraminiferal-based transfer functions. The cumulative transfer functions suggest that the performance improves during the first six sample intervals of the time-series dataset with reconstruction differing by 1.2 m and remains constant thereafter.

]]> Benjamin P. Horton et al.