Letting the plants speak: Law, landscape and conservation.

The Botany Wetlands are the contemporary remnant of a formerly extensive coastal freshwater wetland in the inner-urban suburbs of Sydney (Australia). This site supports a range of ecosystem services, including human physical and mental health benefits, filtration of stormwater runoff from a highly urban and industrial catchment, and accommodation space for floodwater. The wetlands also provide habitat to migratory water birds and act as a connective habitat corridor and refuge for native flora and fauna including endangered ecological communities recognised in state and national legislation. Current management strategies and 'on the ground' practices are informed by a hierarchy of laws and management plans that act to create and reinforce a specific narrative in the material landscape. Here we consider the ecological history of the wetlands, derived from paleoecological data, in the context of this complex network of governance entanglements. We argue that the system bears little resemblance to its long-term character and has been made and continually re-made by a portmanteau of inflexible regulatory structures. We suggest that maintaining ecosystem services in such a complex, hybridized sociolegal-biophysical system requires a critical view of both the power relations and physical processes that shape it.

Forest mosaics, not savanna corridors, dominated in Southeast Asia during the Last Glacial Maximum.

The dominant paradigm is that large tracts of Southeast Asia's lowland rainforests were replaced with a "savanna corridor" during the cooler, more seasonal climates of the Last Glacial Maximum (LGM) (23,000 to 19,000 y ago). This interpretation has implications for understanding the resilience of Asia's tropical forests to projected climate change, implying a vulnerability to "savannization". A savanna corridor is also an important foundation for archaeological interpretations of how humans moved through and settled insular Southeast Asia and Australia. Yet an up-to-date, multiproxy, and empirical examination of the palaeoecological evidence for this corridor is lacking. We conducted qualitative and statistical analyses of 59 palaeoecological records across Southeast Asia to test the evidence for LGM savannization and clarify the relationships between methods, biogeography, and ecological change in the region from the start of Late Glacial Period (119,000 y ago) to the present. The pollen records typically show montane forest persistence during the LGM, while δ13C biomarker proxies indicate the expansion of C4-rich grasslands. We reconcile this discrepancy by hypothesizing the expansion of montane forest in the uplands and replacement of rainforest with seasonally dry tropical forest in the lowlands. We also find that smooth forest transitions between 34,000 and 2,000 y ago point to the capacity of Southeast Asia's ecosystems both to resist and recover from climate stressors, suggesting resilience to savannization. Finally, the timing of ecological change observed in our combined datasets indicates an 'early' onset of the LGM in Southeast Asia from ~30,000 y ago.

Increasing carbon, nutrient and trace metal accumulation driven by development in a mangrove estuary in south Asia.

Mangrove forests sequester organic carbon, nutrients and toxic metals sorbed to fine sediment, and thus restrict the mobility of pollutants through estuarine environments. However, mangrove removal and environmental degradation caused by industrial activity and urban growth can impact the ability of mangrove communities to provide these critical ecosystem services. Here, we use sediment profiles from an impacted tropical estuary in southwest India to provide a c. 70-year record of carbon, nutrient and trace metal burial in the context of rapid urban development and the systemic removal of mangrove communities. Our results show that carbon and nutrient accumulation rates increase sharply during the 1990's in accordance with the high rates of deforestation. Nitrogen and phosphorus accumulation rates increased fourfold and twofold, respectively, during the same period. Organic carbon accumulation was fivefold higher than the global average during this period, reflecting intense deforestation during the last three decades. The enrichment of Hg, Zn, Pb, Mo, Ni, Cu and Mn demonstrate clear anthropogenic impact starting in the 1950's and peaking in 1990. Mercury, the trace metal with the highest enrichment factor, increased sevenfold in the most recent sediments due to increased fossil fuel emissions, untreated water and incineration of medical waste and/or fertilizers used in aquaculture. Organic carbon isotope (δ13C) and C:N molar ratios indicate shifts to more terrestrial-derived source of organic matter in the most recent sediments reflecting growing deforestation of which may be prevalent in southeast Asia due to increasing development. This study emphasizes the critical role played by mangrove ecosystems in attenuating anthropogenically-derived pollutants, including carbon sequestration, and reveals the long-term consequences of mangrove deforestation in the context of rapidly developing economies.

Palaeoenvironmental proxies indicate long-term development of agro-pastoralist landscapes in Inner Asian mountains.

A growing body of archaeological research on agro-pastoralist populations of the Inner Asian mountains indicates that these groups adapted various systems of mobile herding and cultivation to ecotopes across the region from as early as 5000 BP. It has been argued that these adaptations allowed the development of flexible social-ecological systems well suited to the long-term management of these mountain landscapes. At present, less attention has been paid to examining the long-term ecological legacy of these adaptations within the sedimentary or palaeoenvironmental record. Here we present sediment, palynomorph and charcoal data that we interpret as indicating agro-pastoralist environmental perturbations, taken from three cores at middle and high altitudes in the Kashmir Valley at the southern end of the Inner Asian mountains. Our data indicate spatially and temporally discontinuous patterns of agro-pastoralist land use beginning close to 4000 BP. Periods of intensification of upland herding are often coincident with phases of regional social or environmental change, in particular we find the strongest signals for agro-pastoralism in the environmental record contemporary with regionally arid conditions. These patterns support previous arguments that specialised agro-pastoralist ecologies across the region are well placed to respond to past and future climate deteriorations. Our data indicating long-term co-evolution of humans and landscape in the study area also have implications for the ongoing management of environments generally perceived as "pristine" or "wilderness".

The effect of proximity to protected areas on community adaptation to environmental change.

The consequences of protected areas for proximal human communities are diverse. Protected areas can alleviate poverty by providing a range of economic opportunities for people that live and work within them. Equally, however, they may also disempower and disposes local communities. For communities adapting to systemic environmental change, proximity to protected areas can act to limit potential adaptive pathways. Here, we employ social science methods to explore the impact of an internationally significant protected area on adjacent communities in the Tonle Sap Lake basin, Cambodia. Semi-structured interviews, informed by a scenario framework, reveal an awareness of declining fish yields and a perceived lack of economic alternatives. Vulnerability to hydroclimatic extremes, particularly storms, flood, drought and - increasingly - fire, are exacerbated as a result of proximity to the protected area. We conclude that the impact of protected areas on local communities is heterogenous, and that the development of adaptive and effective management policies requires sensitivity to local conditions and impacts.

Assessment of the temporal retention of mercury and nutrient records within the mangrove sediments of a highly impacted estuary.

Mangrove ecosystems are dynamic and biodiverse environments with the capacity to sequester more organic carbon per unit area, per time, than terrestrial forests, yet are among one of the most heavily degraded ecosystems on Earth. Here, we quantify trace metal, nutrient and carbon accumulation rates in a tropical mangrove environment in northeast Brazil, a region that has been rapidly developed over the past seven decades. Carbon accumulation rate results show modest or no increase since the 1950's, when major development occurred in the region. Organic carbon isotope (δ13C) and C:N molar ratios indicate that the OM is primarily derived from autochthonous C3 plant sources. However, the most recent sediments revealed changes from terrestrial to alga-derived source of OM, which is consistent with the increase of total nitrogen, δ15N and total phosphorous content in the last seven decades, suggesting anthropogenic impact. Furthermore, the Hg enrichment factor (EF) in mangrove sediments is shown to have increased 13-fold since the 1960's, highlighting the ability of tropical mangrove systems in trap filtering pollutants from proximal urban development.

Historical socioecological transformations in the global tropics as an Anthropocene analogue.

Large, low-density settlements of the tropical world disintegrated during the first and second millennia of the CE. This phenomenon, which occurred in South Asia, Southeast Asia, and Mesoamerica, is strongly associated with climate variability and extensive landscape transformation. These profound social transformations in the tropical world have been popularized as "collapse," yet archaeological evidence suggests a more complex and nuanced story characterized by persistence, adaptation, and resilience at the local and regional scales. The resulting tension between ideas of climate-driven collapse and evidence for diverse social responses challenges our understanding of long-term resilience and vulnerability to environmental change in the global tropics. Here, we compare the archetypal urban collapse of the Maya, in modern Belize, Guatemala, Honduras, and Mexico, during the 8th to 11th centuries CE, and the Khmer in modern Cambodia, Laos, Thailand, and Vietnam during the 14th to 15th centuries CE. We argue that the social response to environmental stress is spatially and temporally heterogenous, reflecting the generation of large-scale landesque capital surrounding the urban cores. Divergences between vulnerable urban elite and apparently resilient dispersed agricultural settlements sit uncomfortably with simplistic notions of social collapse and raise important questions for humanity as we move deeper into the Anthropocene.

Mangrove carbon and nutrient accumulation shifts driven by rapid development in a tropical estuarine system, northeast Brazil.

Mangrove environments are important for maintaining biodiversity and carbon cycling. However, these systems are being degraded at alarming rates around the world, particularly in rapidly developing regions. Here, we examine a sediment profile from a mangrove forest near a large port complex at Suape, northeast Brazil, in order to assess the impact of rapid urbanization and industrialization. We find that total organic carbon (TOC) and total nitrogen (TN) accumulation rates have increased in the estuary since the 1980's, directly related to rapid urban development. The TN and heavy δ15N values in the sediment column suggest increasing anthropogenic influences. In contrast, heavy metal fluxes did not increase during these transitions. The increase in TOC and TN accumulation rates during the past four decades highlight the significant role mangrove areas play as sinks for anthropogenically enhanced nutrients in poorly-understood tropical areas.

Geochemical signatures of acidic drainage recorded in estuarine sediments after an extreme drought.

Extreme prolonged drought over south-eastern Australia a decade ago (the Millennium Drought, 1996-2010) triggered extensive acid sulfate soil oxidation and associated acidification. Whilst the significant release of metal-enriched drainage has been documented during this event, the fate of these elements in receiving systems is still largely unknown. Here we investigate the spatial distribution, chemical partitioning, and potential bioavailability of S, Fe, Mn, Al, trace metals (V, Cr, Co, Ni, Cu, Pb) and rare earth elements in the surficial sediments of Lake Albert, South Australia; a system that received prolonged (2007-2011) acidic drainage during the Millennium Drought. The highest concentrations of all metals (Enrichment Factors ranging from 1.06-1.97) were observed in the sediments closest to shorelines where sulfidic material were oxidised, generating metal-enriched acidic drainage. Localised enrichment indicates metals have not been completely redistributed across the system following their initial deposition by physical (wind-driven resuspension) or chemical (diagenetic and redox changes) processes. Based on selective extraction data, these metals are likely partitioned as discrete sulfides (Pb) or are with organic material (V, Cr, Cu, Pb, REEs), Fe monosulfides (V, Co, Ni), or pyrite (Co, Ni, Pb). Lake-wide enrichment of trace metals Cr (mean concentration 57 ppm), Ni (39 ppm), Cu (36 ppm), and Pb (24 ppm) relative to other Lower Murray River sites is also evident, suggesting that metal contamination associated with acidic drainage is not restricted to near-source sites. Importantly, the mobilisation, transport, and accumulation of metals is controlled by sediment transport pathways and system hydrology and will thus function differently under varying states of geomorphology, climate, and anthropogenic modification. Our study shows that extreme drought is recorded as a lasting geochemical signature in estuarine sediments, demonstrating that metal and rare earth element geochemistry provides insights into the distribution and behaviour of contaminants mobilised into dynamic, anthropogenically altered estuaries.

Geoarchaeological evidence from Angkor, Cambodia, reveals a gradual decline rather than a catastrophic 15th-century collapse.

Alternative models exist for the movement of large urban populations following the 15th-century CE abandonment of Angkor, Cambodia. One model emphasizes an urban diaspora following the implosion of state control in the capital related, in part, to hydroclimatic variability. An alternative model suggests a more complex picture and a gradual rather than catastrophic demographic movement. No decisive empirical data exist to distinguish between these two competing models. Here we show that the intensity of land use within the economic and administrative core of the city began to decline more than one century before the Ayutthayan invasion that conventionally marks the end of the Angkor Period. Using paleobotanical and stratigraphic data derived from radiometrically dated sediment cores extracted from the 12th-century walled city of Angkor Thom, we show that indicia for burning, forest disturbance, and soil erosion all decline as early as the first decades of the 14th century CE, and that the moat of Angkor Thom was no longer being maintained by the end of the 14th century. These data indicate a protracted decline in occupation within the economic and administrative core of the city, rather than an abrupt demographic collapse, suggesting the focus of power began to shift to urban centers outside of the capital during the 14th century.

Re-evaluating the occupation history of Koh Ker, Cambodia, during the Angkor period: A palaeo-ecological approach.

Throughout the Angkor period (9th to 15th centuries CE), the Khmer kingdom maintained a series of interconnected cities and smaller settlements across its territory on mainland Southeast Asia. One such city was Koh Ker, which for a brief period in the 10th century CE even served as a royal capital. The complexity of the political landscape meant the Khmer kings and the elite were particularly mobile through the Angkor period, and rupture in royal houses was common. However, while the historical record chronicles the 10th century migration of the royal seat from Koh Ker back to Angkor, the fate of Koh Ker's domestic population has remained unknown. In this article, we reconstruct the settlement history of Koh Ker, using palaeoecological and geoarchaeological techniques, and show that human activity and land use persisted in the city for several centuries beyond the city's abandonment by the royal court. These results highlight the utility of multi-proxy environmental reconstructions of Khmer urban settlements for re-evaluating prevailing assumptions regarding the use and occupation of Angkor-period cities.

The demise of Angkor: Systemic vulnerability of urban infrastructure to climatic variations.

Complex infrastructural networks provide critical services to cities but can be vulnerable to external stresses, including climatic variability. This vulnerability has also challenged past urban settlements, but its role in cases of historic urban demise has not been precisely documented. We transform archeological data from the medieval Cambodian city of Angkor into a numerical model that allows us to quantify topological damage to critical urban infrastructure resulting from climatic variability. Our model reveals unstable behavior in which extensive and cascading damage to infrastructure occurs in response to flooding within Angkor's urban water management system. The likelihood and extent of the cascading failure abruptly grow with the magnitude of flooding relative to normal flows in the system. Our results support the hypothesis that systemic infrastructural vulnerability, coupled with abrupt climatic variation, contributed to the demise of the city. The factors behind Angkor's demise are analogous to challenges faced by modern urban communities struggling with complex critical infrastructure.

Metal enrichment in estuarine sediments proximal to acid sulfate soils as a novel palaeodrought proxy.

Persistent drought over eastern Australia at the turn of the last millennium reduced stream flow in Australia's largest and most economically important drainage basin. Low water levels in the basin's terminal lakes triggered widespread pyrite oxidation, which altered surface water chemistry and released metals into the environment. The frequency of these events, and the links between drought and acid sulfate soil activation, are not known because the historical and instrumental records are short. Here, we present a Holocene-aged record of trace metal enrichment from Lake Albert-part of the terminal Lower Lakes system of the Murray-Darling Basin, Australia-that demonstrates the potential of trace elements mobilised during acidification events for palaeodrought reconstructions. Symptomatic metals were measured from a core of clayey sediment to form a multi-element assemblage that reveals acidification events in the geological past. Correlation with regional climate proxies suggests that climate forcing is significant in driving metal flux to estuarine sinks in acid sulfate soil rich landscapes, although the intensity of a drought is not the only variable responsible for acidification intensity. The constructed record indicates that regional climate moved from a generally humid climate phase with intermittent droughts, to a more arid climate at ~5.2ka which prevailed until ~1.7ka. Following conditions were relatively wet with low climatic variability through till European Settlement. Enrichment is observed coincident with both the 1982-83 drought and Millennium Drought, the latter of which reaching an intensity unsurpassed in the last ~4.8ka, likely a product of anthropogenic changes to the Lower Murray-Darling Basin system.

A Novel Electrocardiogram Algorithm Utilizing ST-Segment Instability for Detection of Cardiopulmonary Arrest in Single Ventricle Physiology: A Retrospective Study.

OBJECTIVE: We evaluated ST-segment monitoring to detect clinical decompensation in infants with single ventricle anatomy. We proposed a signal processing algorithm for ST-segment instability and hypothesized that instability is associated with cardiopulmonary arrests. DESIGN: Retrospective, observational study. SETTING: Tertiary children's hospital 21-bed cardiovascular ICU and 36-bed step-down unit. PATIENTS: Twenty single ventricle infants who received stage 1 palliation surgery between January 2013 and January 2014. Twenty rapid response events resulting in cardiopulmonary arrests (arrest group) were recorded in 13 subjects, and nine subjects had no interstage cardiopulmonary arrest (control group). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Arrest data were collected over the 4-hour time window prior to cardiopulmonary arrest. Control data were collected from subjects with no interstage arrest using the 4-hour time window prior to cardiovascular ICU discharge. A paired subgroup analysis was performed comparing subject 4-hour windows prior to arrest (prearrest group) with 4-hour windows prior to discharge (postarrest group). Raw values of ST segments were compared between groups. A 3D ST-segment vector was created using three quasi-orthogonal leads (II, aVL, and V5). Magnitude and instability of this continuous vector were compared between groups. There was no significant difference in mean unprocessed ST-segment values in the arrest and control groups. Utilizing signal processing, there was an increase in the ST-vector magnitude (p = 0.02) and instability (p = 0.008) in the arrest group. In the paired subgroup analysis, there was an increase in the ST-vector magnitude (p = 0.05) and instability (p = 0.05) in the prearrest state compared with the postarrest state prior to discharge. CONCLUSIONS: In single ventricle patients, increased ST instability and magnitude were associated with rapid response events that required intervention for cardiopulmonary arrest, whereas conventional ST-segment monitoring did not differentiate an arrest from control state.

The environmental impact of Cambodia's ancient city of Mahendraparvata (Phnom Kulen).

The Khmer kingdom, whose capital was at Angkor from the 9(th) to the 14(th)-15(th) century, was founded in 802 by king Jayavarman II in a city called Mahandraparvata, on Phnom Kulen. Virtually nothing more is known of Mahandraparvata from the epigraphic sources, but systematic archaeological survey and excavation have identified an array of cultural features that point to a more extensive and enduring settlement than the historical record indicates. Recent remote sensing data have revolutionized our view, revealing the remains of a city with a complex and spatially extensive network of urban infrastructure. Here, we present a record of vegetation change and soil erosion from within that urban network, dating from the 8(th) century CE. Our findings indicate approximately 400 years of intensive land use, punctuated by discrete periods of intense erosion beginning in the mid 9(th) century and ending in the late 11(th) century. A marked change in water management practices is apparent from the 12(th) century CE, with implications for water supply to Angkor itself. This is the first indication that settlement on Mahendraparvata was not only extensive, but also intensive and enduring, with a marked environmental impact.

How good is a good Fontan? Quality of life and exercise capacity of Fontans without arrhythmias.

BACKGROUND: Poor long-term outcomes are expected after Fontan surgery, but these perspectives have been tainted by the poorly functioning Fontans suffering from arrhythmias. No predictions of outcome can be quoted to the increasing number of Fontan patients free from arrhythmic complications. The parameters determining improved exercise capacity and quality of life in this subgroup are yet unknown. METHODS: Fontan survivors from our institution and living in Victoria were invited to participate in the study if they were more than 10 years of age, and free of arrhythmias. A mean of 17 +/- 4 years after Fontan, 36 patients, 23 with a classical atriopulmonary connection (AP) and 13 with a lateral tunnel (LT) underwent transthoracic echocardiography, cycloergometer exercise study, neurohumoral screening, and assessment of quality of life. RESULTS: The only factor predicting worse exercise capacity was the type of Fontan performed; patients with LT having better exercise capacity than those with AP (percentage of predicted anaerobic threshold: 88 +/- 14% vs 72 +/- 14%, p < 0.005; percentage of predicted VO(2)max: 62 +/- 8% vs 54 +/- 7%, p < 0.005). Endothelin-1 levels were elevated in all patients (2.9 pmol/L, 2.5 to 3.7). Responses from the quality of life measures placed our Fontan cohort mainly within the normal population range. None of the preoperative and postoperative variables adversely affected patients' quality of life. CONCLUSIONS: The anaerobic threshold of arrhythmia-free Fontan patients operated with the lateral tunnel technique was relatively preserved. Despite restricted exercise capacity, Fontan patients, provided that they are free of arrhythmias, have a normal quality of life reflected in their reports of psychiatric symptoms and family relationships.

The Mekong at climatic crossroads: Lessons from the geological past.

The wetlands of the lower Mekong River Basin are ecologically and socioeconomically significant, but they are threatened by predicted climatic change. The likely response of wetland ecosystems to altered flooding regimes and surface-water chemistry is unknown in detail and difficult to model. One way of exploring the impact of climate change on wetland ecosystems is to utilize proxy environmental data that reveal patterns of change over geological time. In recent years, the coverage and resolution of proxy climatic data have improved markedly in the region. Recent evidence of the South China Sea transgression into southern and central Cambodia and paleobotanical evidence from the Tonle Sap ("Great Lake") and elsewhere allow us to explore how periods of higher-than-present sea level and increased monsoon rainfall in the past have impacted the wetland ecology of the lower Mekong River Basin.

Sediment: curse or blessing for Tonle Sap Lake?

It has been claimed that Tonle Sap Lake is rapidly filling with sediment as a result of increasing sediment yields from the catchment. Infilling of the lake basin would have serious implications for the magnitude of flooding in central Cambodia and the Mekong Delta region and threaten the lake's unique ecosystem. In this article, we synthesize the results of radiocarbon dating of sediment cores and hydrodynamic modeling results to provide an empirically based assessment of this issue. We find that current sedimentation rates within the lake basin proper are low and have been for several millennia. However, sedimentation at the lake margin and in its floodplain is relatively high, which presents a range of issues for riparian communities.

The Fontan procedure: contemporary techniques have improved long-term outcomes.

BACKGROUND: To determine whether patients undergoing the lateral tunnel and extracardiac conduit modifications of the Fontan procedure have better outcomes than patients undergoing a classical atriopulmonary connection. METHODS AND RESULTS: Between 1980 and 2000, 305 consecutive patients underwent a Fontan procedure at our institution. There were 10 hospital deaths (mortality: 3%) with no death after 1990. Independent risk factors for mortality were preoperative elevated pulmonary artery pressures (P=0.002) and common atrioventricular valve (P=0.04). Fontan was taken down during hospital stay in 7 patients. A mean of 12+/-6 years of follow-up was obtained in the 257 nonforeign Fontan survivors. Completeness of concurrent follow-up was 96%. Twenty-year survival was 84% (95% CI: 79 to 89%). Recent techniques improved late survival. The 15-year survival after atriopulmonary connection was 81% (95% CI: 73% to 87%) versus 94% (95% CI: 79% to 98%) for lateral tunnel (P=0.004). Nine pts required heart transplantation (8 atriopulmonary connection, 1 lateral tunnel). Undergoing a Fontan modification independently predicted decreased occurrence of arrhythmia, and 15-year freedom from SVT was 61% (95% CI: 51% to 70%) for atriopulmonary connection versus 87% (95% CI: 76% to 93%) for lateral tunnel (P=0.02). Freedom from Fontan failure (death, take-down, transplantation, or NYHA class III-IV) was 70% (95% CI: 58% to 79%) at 20 years. After extra-cardiac conduits, no death, SVT, or failure was observed. CONCLUSIONS: The Fontan procedure remains a palliation, but outcomes of patients have improved. Better patient selection minimizes hospital mortality. Patients with lateral tunnel and extracardiac conduit modifications experience less arrhythmia and are likely to have failure of their Fontan circulation postponed.