Broad Geographic Regions Research Articles

Smooth regional estimation of low-flow indices: physiographical space based interpolation and top-kriging

Abstract. Recent studies highlight that spatial interpolation techniques of point data can be effectively applied to the problem of regionalization of hydrometric information. This study compares two innovative interpolation techniques for the prediction of low-flows in ungauged basins. The first one, named Physiographical-Space Based Interpolation (PSBI), performs the spatial interpolation of the desired streamflow index (e.g., annual streamflow, low-flow index, flood quantile, etc.) in the space of catchment descriptors. The second technique, named Topological kriging or Top-kriging, predicts the variable of interest along river networks taking both the area and nested nature of catchments into account. PSBI and Top-kriging are applied for the regionalization of Q355 (i.e., a low-flow index that indicates the streamflow that is equalled or exceeded 355 days in a year, on average) over a broad geographical region in central Italy, which contains 51 gauged catchments. The two techniques are cross-validated through a leave-one-out procedure at all available gauges and applied to a subregion to produce a continuous estimation of Q355 along the river network extracted from a 90m elevation model. The results of the study show that Top-kriging and PSBI present complementary features. Top-kriging outperforms PSBI at larger river branches while PSBI outperforms Top-kriging for headwater catchments. Overall, they have comparable performances (Nash-Sutcliffe efficiencies in cross-validation of 0.89 and 0.83, respectively). Both techniques provide plausible and accurate predictions of Q355 in ungauged basins and represent promising opportunities for regionalization of low-flows.

Browse biomass removal and nutritional condition of moose Alces alces

AbstractWe present methodology for assessing browse removal to help evaluate resource limitation among moose Alces alces populations in large, potentially remote areas of boreal forest. During 2000‐2007, we compared proportional removal (ratio of browse consumption to browse production) in eight areas of Interior Alaska, USA, with multi‐year twinning rates of the respective moose populations. Several prior studies concluded that twinning rate provided an index of the nutritional condition of moose. We theorized that a plant‐based sampling of proportional use of browse by moose in late winter would inversely correlate with the nutritional condition of moose. We sampled willow Salix spp., quaking aspen Populus tremuloides, balsam poplar P. balsamifera and Alaska paper birch Betula neoalaskana, i.e. plants with current annual growth (CAG) between 0.5 and 3.0 m above ground. We estimated the biomass of CAG and biomass removed by moose based on bite diameters and diameter‐mass regressions specific to each browse species. Mean browse removal by moose varied among study areas from 9 to 43% of CAG. Moose twinning rate (range: 7‐64%) was inversely correlated with proportional browse removal by moose (Spearman's rho = −0.863, P < 0.005). Proportional browse removal appeared useful in linking foraging ecology and population dynamics of moose in Alaska, and the technique may be used to quantify resource limitation in moose populations inhabiting boreal forest in a broader geographic region.

Stratigraphic distribution of marine fossils in North America

The stratigraphic distribution of fossils reflects a combination of physical and biological factors. Although many studies have addressed the distribution of fossils at a basin scale and within sedimentary sequences spanning 10 4 –10 6 yr, little is known about the distribution of fossils within longer duration sedimentary successions covering broad geographic regions. Here we combine a North American macrostratigraphic database with fossil occurrence data from the Paleobiology Database to quantify the stratigraphic distribution of fossils within hiatus-bound marine sedimentary rock packages that have a mean duration of 10 7 yr. We find that fossil collections and marine genera are, when averaged over all Phanerozoic sedimentary rock packages, more abundant than expected in the top 40% of package durations, and less common than expected in the bottom ∼25%. Generic first and last appearance datums (FADs and LADs) in North America are not randomly distributed among fossil collections. Instead, LADs are more common than expected in the top ∼20% of package durations, whereas FADs are more uniformly distributed. This result is not consistent with an unconformity-related sampling bias, but is indicative of greater congruence in the temporal scales over which genus extinction and regression occur than genus initiation and transgression. These results support the hypothesis that macroevolution, particularly genus extinction, and large-scale patterns of sedimentation share a common set of forcing mechanisms that are related to the formation and destruction of shallow-marine habitats.

Sensitivity to Foliar Anthocyanin Content of Vegetation Indices Using Green Reflectance

Anthocyanins are nonphotosynthetic water-soluble pigments associated with the resistance of plants to environmental stresses such as drought, low soil nutrients, high radiation, herbivores, and pathogens. Information on the absolute and relative amounts of anthocyanins allows evaluating the physiological conditions of plants and their responses to stress and has the potential for evaluating plant species diversity across broad geographic regions. As anthocyanins absorb radiation in the green region of the electromagnetic spectrum (with a peak of absorption at around 540-560 nm), broadband vegetation indices that use this spectral region in their formulation will exhibit sensitivity to their presence. In this letter, we evaluate the sensitivity of four broadband vegetation indices using reflectance in the green spectral region to foliar anthocyanin content. Among the indices tested, the visible atmospherically resistant vegetation index was found to be closely and linearly related to the relative amount of foliar anthocyanin across five different species (the root-mean-square error of the prediction is ca. 0.1, and the relative error is below 20%). While this result was obtained at leaf level, it opens new possibilities for analyzing anthocyanin content and composition across multiple scales by means of spacecraft-mounted broadband sensor systems such as Landsat Thematic Mapper, Landsat Enhanced Thematic Mapper Plus, and Moderate Resolution Imaging Spectroradiometer.

High Genetic Diversity and Fine-Scale Spatial Structure in the Marine Flagellate Oxyrrhis marina (Dinophyceae) Uncovered by Microsatellite Loci

Free-living marine protists are often assumed to be broadly distributed and genetically homogeneous on large spatial scales. However, an increasing application of highly polymorphic genetic markers (e.g., microsatellites) has provided evidence for high genetic diversity and population structuring on small spatial scales in many free-living protists. Here we characterise a panel of new microsatellite markers for the common marine flagellate Oxyrrhis marina. Nine microsatellite loci were used to assess genotypic diversity at two spatial scales by genotyping 200 isolates of O. marina from 6 broad geographic regions around Great Britain and Ireland; in one region, a single 2 km shore line was sampled intensively to assess fine-scale genetic diversity. Microsatellite loci resolved between 1–6 and 7–23 distinct alleles per region in the least and most variable loci respectively, with corresponding variation in expected heterozygosities (He) of 0.00–0.30 and 0.81–0.93. Across the dataset, genotypic diversity was high with 183 genotypes detected from 200 isolates. Bayesian analysis of population structure supported two model populations. One population was distributed across all sampled regions; the other was confined to the intensively sampled shore, and thus two distinct populations co-occurred at this site. Whilst model-based analysis inferred a single UK-wide population, pairwise regional FST values indicated weak to moderate population sub-division (0.01–0.12), but no clear correlation between spatial and genetic distance was evident. Data presented in this study highlight extensive genetic diversity for O. marina; however, it remains a substantial challenge to uncover the mechanisms that drive genetic diversity in free-living microorganisms.

Using fine-scale GIS data to assess the relationship between intra-annual environmental niche variability and population density in a local stream fish assemblage

Summary 1. Geographic information systems (GIS) have recently proved useful for estimating the environmental niche of species across broad geographic regions. However, the application of these niche-based GIS techniques has yet to be extensively applied to local systems. The assumptions of the methods are transferable across scales: species exist across a range of habitats, and these habitats represent a gradient of suitability that can be characterized using multivariate environmental data in association with known species occurrences. 2. Habitat availability and species’ niche characteristics are often considered to be important predictors of population density. However, seasonal habitat variability and stochastic events have been hypothesized to limit interactions among species and confound the relationship between available habitat, species niche characteristics and community structure. This research examines the relationship between environmental niche breadth and niche position and population density among species of stream fishes in a seasonally variable environment using a novel application of fine-scale GIS data. 3. Niche breadth and niche position were estimated for 11 species in a local assemblage using five fine-scale (0·5 m) GIS-based environmental data sets collected during four different times of the year (July, October, January, April). We compared niche measures to variation in population density among species to determine whether environmental niche characteristics, in the context of available habitat, explain variation in numbers of individuals among species. 4. Variation in population density among species in the October sample was predicted by niche breadth measures (R2 = 0·752), while variation in population density among species in the January sample was predicted by a model incorporating measures of both niche breadth and niche position (R2 = 0·953). Measures of niche breadth and niche position were not correlated with variation in population density in the July and April samples. 5. Species presence and local abundance are often assumed to be predictable based on the availability of suitable habitat. However, little effort has been directed at understanding the influence of both niche breadth and niche position on local abundance. Our results suggest that the amount and distribution of available habitat can be a strong predictor of interspecific variation in population density, even in seasonally variable environments.

Nitrogen and sulphur deposition and the growth of Sphagnum fuscum in bogs of the Athabasca Oil Sands Region, Alberta

One of the consequences of ongoing development of the oil sands reserve in the Athabasca Oil Sands Region (AOSR) near Fort McMurray, Alberta, Canada (56° 39' N, 111° 13' W) is an increase in emissions of nitrogen (N) and sulphur (S), with an attendant increases in regional atmospheric N and S deposition. Regional land cover across northeastern Alberta is a mixture of Boreal Mixedwood, Boreal Highlands, and Subarctic areas. Peatlands occupy between 22 and 66% of these natural regions, and the land cover of bogs varies between 6.7% in the Mixedwood Region to 46% in the Subarctic Region. Ombrotrophic bog ecosystems may be especially sensitive to atmospheric deposition of N and S. Across 10 ombrotrophic bog sites in the AOSR over four years (2005– 2008), we found no evidence of elevated deposition of NH4 +-N, NO3 –-N, total inorganic nitrogen (TIN; NH4 +-N plus NO3 –-N), or SO4 2–-S, with values measured using ion exchange resin collectors averaging 0.61 ± 04, 0.20 ± 0.01, 0.81 ± 0.04, and 1.14 ± 0.06 kg ha–1 y–1, respectively. Vertical growth and net primary production of Sphagnum fuscum, an indicator of elevated deposition, did not differ consistently across sites, averaging 11.8 ± 0.2 mm y–1 and 234 ± 3.3 g m–2 y–1, respectively, over the four years. Neither vertical growth nor net primary production of S. fuscum was correlated with growing season atmospheric N or S deposition. Our data provide a valuable benchmark of background values for monitoring purposes in anticipation of increasing N and S deposition over a broader geographic region within the AOSR.

Multi-scale spatial variation in stable isotope and fatty acid profiles amongst temperate reef species: implications for design and interpretation of trophic studies

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 410:25-41 (2010) - DOI: https://doi.org/10.3354/meps08649 Multi-scale spatial variation in stable isotope and fatty acid profiles amongst temperate reef species: implications for design and interpretation of trophic studies M. A. Guest1, A. J. Hirst1,2,*, P. D. Nichols3,4, S. D. Frusher1 1Tasmanian Aquaculture and Fisheries Institute, University of Tasmania, Hobart, Tasmania, Australia 2Marine and Freshwater Fisheries Research Institute, Queenscliff, Victoria, Australia 3CSIRO Marine and Atmospheric Research, Hobart, Tasmania, Australia 4Antarctic and Climate Ecosystems, University of Tasmania, Hobart, Tasmania, Australia *Corresponding author. Email: alastair.hirst@dpi.vic.gov.au ABSTRACT: Stable isotopes of carbon and nitrogen and fatty acid analyses are increasingly being used in combination to determine the trophic structure of marine systems. For stable isotopes, the variability in carbon and nitrogen isotopic signatures has long been recognised and has been characterised for some taxa. Whilst it is known that metabolic processes may influence fatty acid profiles, the spatial variability of fatty acid profiles has not been documented. Understanding at what scale these 2 biochemical tracers vary, and if the scale of variability corresponds between tracers, is crucial for the correct design and interpretation of combined tracers in trophic studies. This study is the first to examine spatial variability in fatty acid profiles per se, and in combination with stable isotope ratios in the same organisms at multiple spatial scales. We used a spatially hierarchical design which sampled across broad geographic regions, reefs within regions, and also between different parts of macroalgal plants common on temperate reefs. For stable isotopes of carbon and nitrogen, variability was greatest at intermediate spatial scales (between locations within regions, and sites within locations). In contrast, fatty acid profiles showed the greatest variation amongst individual replicates of lobster, abalone and macroalgae. This study demonstrates that for the increasing number of trophic studies using combined biochemical tracers, sampling design should cater to the differences in the variability of each tracer technique and allocate sampling accordingly. KEY WORDS: Stable isotopes · Fatty acid analysis · Nested hierarchical design · Multivariate variance components · Tasmania Full text in pdf format PreviousNextCite this article as: Guest MA, Hirst AJ, Nichols PD, Frusher SD (2010) Multi-scale spatial variation in stable isotope and fatty acid profiles amongst temperate reef species: implications for design and interpretation of trophic studies. Mar Ecol Prog Ser 410:25-41. https://doi.org/10.3354/meps08649 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 410. Online publication date: July 14, 2010 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2010 Inter-Research.

The Legacy of Hurricane Mitch: Lessons from Post‐disaster Reconstruction in Honduras

Around the world disaster vulnerability is on the rise. The incidence and intensity of disasters have increased in recent decades with lives being shattered and resources being destroyed across broad geographic regions each year. As it swept across the Honduran landscape, the exceptional size, power and duration of Hurricane Mitch abruptly and brutally altered the already diminished economic, social, and environmental conditions of the population. In the aftermath of the disaster a group of seven socio-environmental scientists set out to investigate the root causes of the heightened vulnerability that characterized pre-Mitch Honduras, the impact of the catastrophe on the local society, and the subsequent recovery efforts. Edited by Marisa O. Ensor, this volume presents the findings of their investigation. The Legacy of Hurricane Mitch offers a comprehensive analysis of the immediate and long-term consequences of Hurricane Mitch in Honduras. Based on longitudinal ethnographic fieldwork and environmental assessments, this volume illustrates the importance of adopting an approach to disaster research and practice that places ?natural trigger events within their political, cultural, and socio-economic contexts. The contributors make a compelling case against post-disaster recovery efforts that limit themselves to alleviating the symptoms, rather than confronting the root causes of the vulnerability that prefigured the disaster.

Abstract 910: Isothiocyanate-gene interactions and endometrial cancer risk: the California Teachers Study

Abstract Background: Cruciferous vegetables may reduce the risk of endometrial cancer, although the evidence is mixed. However, as observed for other cancers, this association may be modified by polymorphic variation in phase I genes (e.g., CYP1A1 which also controls estrogen metabolism) and phase II genes (e.g., GSTs). Such interactions have not been previously examined for endometrial cancer. Methods: A nested case-control study of type 1 invasive endometrial cancer was conducted within the California Teachers Study (CTS) cohort. 320 women (age≥50) with incident cancer, identified through the California Cancer Registry and diagnosed after joining the cohort and before January 2005, and 629 controls, frequency-matched on age, race/ethnicity, and broad geographic region of residence within California, provided a DNA sample and had complete epidemiologic data. Consumption of cruciferous vegetables was assessed using a validated food-frequency questionnaire at the time women joined the cohort in 1995-96. Isothiocyanate (ITC) consumption was estimated using values obtained from prior analysis of California foods and was based on frequency and portion size of usual consumption of cruciferous vegetables. Selected single nucleotide polymorphisms (SNP) in several phase I and II genes were genotyped. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using unconditional logistic regression, adjusting for matching variables. Results: Neither cruciferous vegetable or ITC intake, nor variants in CYP1A1 MspI (rs4646903), GSTM1, or GSTT1 were directly associated with endometrial cancer risk. The Val/Val genotype of GSTP1 Ile105Val was associated with increased endometrial cancer risk (OR=1.64, 95% CI: 1.07-2.53) and the Val/Val genotype of CYP1A1 Ile462Val was associated with reduced risk (OR=0.63, 95% CI: 0.37-1.08). There was no interaction, however, between cruciferous vegetable or ITC intake and any of these genes. Conclusion: Consistent with some, but not all, previous studies we observed a significant reduction in risk associated with the Val/Val genotype of CYP1A1 Ile462Val. This study also confirms a single previous, but smaller report of an association between type I endometrial cancer and the Ile105Val SNP in GSTP1. However, while the prospective assessment of dietary intake minimizes recall bias, we found no evidence of an interaction between these genetic variants and ITC consumption. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 910.

Old Regions, New States: Why is Governance Weak in the Indus–Ganges Plain?

A region of states considered ‘critical’ and ‘in danger’ of state failure—Pakistan, Nepal, Bhutan and Bangladesh—lie on India's land borders. Although India itself is at low risk of state failure, a number of provincial Indian states in the Ganges plain—the so-called BIMARU states of Bihar, Madhya Pradesh, Rajasthan and Uttar Pradesh—share many features of state weakness and poor developmental performance. This article canvasses a range of explanations for why there are so many ineffective and weak national and provincial governments in this broad geographic region. The article looks at the evidence for pre-colonial influences (kinship, social and political organisation), colonial transformations (land settlements), and post-colonial developments.

A theory (involving tropical cyclones) on the formation of coarse-grained sand beach ridges in NE Australia

Abstract A theory is presented that coarse-grained sand beach ridge plains in northeastern Australia have developed their final form (i.e. the height of the ridges above sea level) as a result of marine inundations generated by intense tropical cyclones. Although winds generated during such tempests are of more than sufficient velocity to transport coarse-grained sands the beach is typically inundated by the storm surge and waves during these events and hence there is no viable source for aeolian sand transport. Numerical storm surge and shallow water wave models are run for two sites (Cairns and Cowley Beach) and the results indicate that only wave run-ups generated by category 3 or more intense tropical cyclones can deposit the final units of sediment onto the sand beach ridges at these locations. It is suggested that as a sand beach ridge increases in height, via successive deposition of units of sand, progressively higher marine inundations are required to reach the ridge crest. The final height of the sand beach ridge is dependent upon the interplay of sediment supply rates to the coastal system and the intensity and frequency of tropical cyclones. If tropical cyclones are responsible for the final form of the sand beach ridges then these sequences can be used to assess the long-term climatology of intense tropical cyclones over this broad geographical region.

By Foot, Bus or Car: Children's School Travel and School Choice Policy

Many school districts in the United States allow parents to choose which school their child attends ('school choice’ or ‘magnet schools’) while other school districts require students to attend their nearest (‘neighborhood’) school. Such policies influence children's transportation. We survey elementary-school parents in St. Paul and Roseville, Minnesota, to discover how children travel to school and underlying factors influencing parent's choice of their child's travel mode. From this information we develop a statistical model of travel mode choice. We find that children's commute mode and parental attitudes towards school selection differ by school type (magnet versus neighborhood), income, and race. Relative to neighborhood schools, magnet schools draw from broader geographic regions, have lower rates of walking, bicycling, and commuting by automobile, and higher busing rates. Parent attitudes towards transportation also differ by race and school type. For example, parents of nonwhite and magnet school students placed greater-than-average importance on bus service and quality. This paper highlights the potentially unintended influence of school district policy on school commute mode.

Assessment of threats to ecosystems in South America

South America is blessed with both world-leading levels of biodiversity, and world-record breaking levels of habitat conversion in some areas. Under this highly dynamic context, sound conservation planning is needed and one component of effectively prioritising conservation interventions is through the assessment of threats to natural ecosystems. Here we present a continent-wide and spatially explicit threats assessment to natural ecosystems. A conceptual framework is presented which quantifies threat as a function of both the magnitude of the impacts of specific damaging human activities, and the variable response of different ecosystems to those impacts. The framework is then applied on seven different threat layers (accessibility, conversion to agriculture, fires, grazing pressure, infrastructure, oil and gas, recent conversion) to map out and spatially quantify the level of threat expected over the coming 2–5 year period. An aggregate threat layer is calculated, and the threats to major habitat types are evaluated. Tropical and Subtropical Grasslands, Savannas and Shrublands and Flooded Grasslands and Savannas are found to be under the greatest threat (0.36 and 0.35 aggregate threat respectively), both threatened most by fires (0.96), the former by accessibility (0.72) and the latter by grazing pressure (0.62). Tropical and Subtropical Moist Broadleaf Forests are the least threatened of all ecosystems (0.13), closely followed by Montane Grasslands and Shrublands (0.14). Overall, accessibility is shown to be a major issue across much of the continent, and fires are a significant threat in some identified regions. The results are being used by The Nature Conservancy to target conservation efforts in the region, and also to drive policies for threat abatement. Furthermore, the conceptual framework and methodology is applicable to any region and presents a useful means of prioritising conservation interventions across broad geographic regions.

The relationship between mangrove and saltmarsh communities in the Sydney region.

Coastal saltmarshes around the world are characterised by belts of vegetation parallel to the shore. The species and communities which define the zones vary geographically such that it is claimed that a particular zonation pattern is a feature of a broad geographical region (Chapman 1974). It has been suggested that the zonation pattern repeats in space the course of succession over time. The most seaward zone occupies the lowest elevation on the shore and is vegetated by pioneer species. As sediment accretes the marsh surface is raised, and thus experiences fewer tidal inundations. The changed physical environment is conducive to the invasion of species which replace the pioneers. However, conditions to seaward are now appropriate for colonisation so that the pioneer species move seaward. With further sedimentation the pioneer zone continues to migrate seaward (Se fig. 1) until a balance between accretion and erosive forces is reached and extension ceases.

A unifying approach for evaluating the condition of wetland plant communities and identifying related stressors

Assessment of vegetation is an important part of evaluating wetland condition, but it is complicated by the variety of plant communities that are naturally present in freshwater wetlands. We present an approach to evaluate wetland condition consisting of: (1) a stratified random sample representing the entire range of anthropogenic stress, (2) field data representing a range of water depths within the wetlands sampled, (3) nonmetric multidimensional scaling (MDS) to determine a biological condition gradient across the wetlands sampled, (4) hierarchical clustering to interpret the condition results relative to recognizable plant communities, (5) classification and regression tree (CART) analysis to relate biological condition to natural and anthropogenic environmental drivers, and (6) mapping the results to display their geographic distribution. We applied this approach to plant species data collected at 90 wetlands of the U.S. Great Lakes coast that support a variety of plant communities, reflecting the diverse physical environment and anthropogenic stressors present within the region. Hierarchical cluster analysis yielded eight plant communities at a minimum similarity of 25%. Wetlands that clustered botanically were often geographically clustered as well, even though location was not an input variable in the analysis. The eight vegetation clusters corresponded well with the MDS configuration of the data, in which the first axis was strongly related (R2 = 0.787, P < 0.001) with floristic quality index (FQI) and the second axis was related to the Great Lake of occurrence. CART models using FQI and the first MDS axis as the response variables explained 75% and 82% of the variance in the data, resulting in 6-7 terminal groups spanning the condition gradient. Initial CART splits divided the region based on growing degree-days and cumulative anthropogenic stress; only after making these broad divisions were wetlands distinguished by more local characteristics. Agricultural and urban development variables were important correlates of wetland biological condition, generating optimal or surrogate splits at every split node of the MDS CART model. Our findings provide a means of using vegetation to evaluate a range of wetland condition across a broad and diverse geographic region.

CLIMATE IN THE DRY CENTRAL ANDES OVER GEOLOGIC, MILLENNIAL, AND INTERANNUAL TIMESCALES1

Over the last eight years, we have developed several paleoenvironmental records from a broad geographic region spanning the Altiplano in Bolivia (18°S–22°S) and continuing south along the western Andean flank to ca. 26°S. These records include: cosmogenic nuclide concentrations in surface deposits, dated nitrate paleosoils, lake levels, groundwater levels from wetland deposits, and plant macrofossils from urine-encrusted rodent middens. Arid environments are often uniquely sensitive to climate perturbations, and there is evidence of significant changes in precipitation on the western flank of the central Andes and the adjacent Altiplano. In contrast, the Atacama Desert of northern Chile is hyperarid over many millions of years. This uniquely prolonged arid climate requires the isolation of the Atacama from the Amazon Basin, a situation that has existed for more than 10 million years and that resulted from the uplift of the Andes and/or formation of the Altiplano plateau. New evidence from multiple terrestrial cosmogenic nuclides, however, suggests that overall aridity is occasionally punctuated by rare rainfall events that likely originate from the Pacific. East of the hyperarid zone, climate history from multiple proxies reveals alternating wet and dry intervals where changes in precipitation originating from the Atlantic may exceed 50%. An analysis of Pleistocene climate records across the region allows reconstruction of the spatial and temporal components of climate change. These Pleistocene wet events span the modern transition between two modes of interannual precipitation variability, and regional climate history for the Central Andean Pluvial Event (CAPE; ca. 18–8 ka) points toward similar drivers of modern interannual and past millennial-scale climate variability. The north-northeast mode of climate variability is linked to El Nino–Southern Oscillation (ENSO) variability, and the southeast mode is linked to aridity in the Chaco region of Argentina.

MAJOR PATHOLOGIC FINDINGS AND PROBABLE CAUSES OF MORTALITY IN BOTTLENOSE DOLPHINS STRANDED IN SOUTH CAROLINA FROM 1993 TO 2006

Although cause-of-death information on bottlenose dolphins (Tursiops truncatus) can be located in the literature, few citations include mortality data over a long period of time covering a broad geographic region. This study describes major pathologic findings and probable causes of death of bottlenose dolphins over a 14-yr period (1993-2006) for the coastal region of South Carolina. Probable causes of death for 97 cases were determined based on gross pathology and histopathology. In an additional 30 cases, probable cause of death was apparent from gross pathology alone, and carcass condition precluded histopathology. Of the 97 dolphins examined grossly and histologically, 30 (31%) likely died of infectious disease and 46 (47%) of noninfectious disease; the cause of death was unknown in 21 (22%). Bacterial infections accounted for the large majority of fatal infections and emaciation was the leading cause of noninfectious mortality. Twelve dolphins were killed by human interactions. Of the 30 dolphins diagnosed from gross examination alone, 23 likely died from human interaction and seven were killed by stingray-spine inflictions. Although the absence of consistent use of microbiology, biotoxin analysis and contaminant testing decreases the conclusiveness of the findings, this study has broad implications in establishing baseline data on causes of death of bottlenose dolphins for future studies and for the detection of emerging diseases.

Low genetic differentiation across three major ocean populations of the whale shark, Rhincodon typus.

BackgroundWhale sharks are a declining species for which little biological data is available. While these animals are protected in many parts of their range, they are fished legally and illegally in some countries. Baseline biological and ecological data are needed to allow the formulation of an effective conservation plan for whale sharks. It is not known, for example, whether the whale shark is represented by a single worldwide panmictic population or by numerous, reproductively isolated populations. Genetic analysis of population structure is one essential component of the baseline data required for whale shark conservation.Methodology/Principal FindingsWe have identified 8 polymorphic microsatellites in the whale shark and used these markers to assess genetic variation and population structure in a panel of whale sharks covering a broad geographic region. This is the first record of microsatellite loci in the whale shark, which displayed an average of 9 alleles per locus and mean Ho = 0.66 and He = 0.69. All but one of the eight loci meet the expectations of Hardy-Weinberg equilibrium. Analysis of these loci in whale sharks representing three major portions of their range, the Pacific (P), Caribbean (C), and Indian (I) Oceans, determined that there is little population differentiation between animals sampled in different geographic regions, indicating historical gene flow between populations. FST values for inter-ocean comparisons were low (P×C = 0.0387, C×I = 0.0296 and P×I = −0.0022), and only C×I approached statistical significance (p = 0.0495).Conclusions/SignificanceWe have shown only low levels of genetic differentiation between geographically distinct whale shark populations. Existing satellite tracking data have revealed both regional and long-range migration of whale sharks throughout their range, which supports the finding of gene flow between populations. Whale sharks traverse geographic and political boundaries during their life history and interbreed with animals from distant populations; conservation efforts must therefore target international protection for this species.

Patterns in reproductive dynamics of burrowing ghost shrimp Trypaea australiensis from small to intermediate scales

Many studies have examined latitudinal differences in reproduction of marine invertebrates, but few have measured variation at small to intermediate scales (kilometres to hundreds of kilometres), which may confound comparisons across broader geographic regions. Here, we examined variation in the reproductive biology of a little-studied species of burrowing ghost shrimp (Trypaea australiensis) at spatial scales ranging from km (between sites within estuaries) to 100s of km (among estuaries), over a 2-year period in south-eastern Australia. Sex ratios of populations were consistently biased towards females through time and space. Although reproduction started in summer months across all spatial scales, there was a pattern of earlier spawning from southern to northern estuaries. Integration of results from previous studies of T. australiensis supported a similar pattern of earlier breeding from high to low latitudes. Fecundity of shrimp increased linearly with female size, but the relationship varied inconsistently across the different spatial scales. Similarly, sizes at maturity varied from small to intermediate scales and observed patterns were not consistent with general predictions e.g. shrimp were smaller and ovigerous at smaller sizes at sites in the southern-most estuary, compared to estuaries further north. We found no differences in the sizes of embryos across the different spatial scales, but confirm that T. australiensis employs a strategy of high fecundity and small embryo size compared to other thalassinidean shrimp. Our results suggest that factors at smaller scales (e.g. food availability) may be important in affecting reproductive dynamics of T. australiensis, but further research is needed in testing hypotheses about patterns observed here. A lack of similar studies on other marine organisms remains an impediment to understanding life-history strategies and the sustainable management and conservation of populations.