Mangrove response to environmental change in Australia's Gulf of Carpentaria

Across their range, mangroves are responding to coastal environmental change. However, separating the influence of human activities from natural events and processes (including that associated with climatic fluctuation) is often difficult. In the Gulf of Carpentaria, northern Australia (Leichhardt, Nicholson, Mornington Inlet, and Flinders River catchments), changes in mangroves are assumed to be the result of natural drivers as human impacts are minimal. By comparing classifications from time series of Landsat sensor data for the period 1987?2014, mangroves were observed to have extended seawards by up to 1.9 km (perpendicular to the coastline), with inland intrusion occurring along many of the rivers and rivulets in the tidal reaches. Seaward expansion was particularly evident near the mouth of the Leichhardt River, and was associated with peaks in river discharge with LiDAR data indicating distinct structural zones developing following each large rainfall and discharge event. However, along the Gulf coast, and particularly within the Mornington Inlet catchment, the expansion was more gradual and linked to inundation and regular sediment supply through freshwater input. Landward expansion along the Mornington Inlet catchment was attributed to the combined effects of sea level rise and prolonged periods of tidal and freshwater inundation on coastal lowlands. The study concluded that increased amounts of rainfall and associated flooding and sea level rise were responsible for recent seaward and landward extension of mangroves in this region.publishersversionPeer reviewe

Australian forested wetlands under climate change:Collapse or proliferation?

Climatically driven perturbations (e.g. intense drought, fire, sea surface temperature rise) can bring ecosystems that are already stressed by long-term climate change and other anthropogenic impacts to a point of collapse. Recent reviews of the responses of Australian ecosystems to climate change and associated stressors have suggested widespread ecosystem collapse is occurring across multiple biomes. Two commonly cited case studies concern forested wetland ecosystems: mangrove forest dieback in northern Australia (2015-16) and riverine forest dieback in the south-east of the continent (2002-09). We present an alternative interpretation that emphasises the dominant signal of climate change effects, rather than the interdecadal signal of climate variability that drives wetland forest dynamics. For both the south-east Australian riverine forests and mangroves of northern Australia, aerial extent remains greater after dieback than in the early 1990s. We interpret dieback and defoliation in both systems as a dry phase response and provide evidence of a current and near-future climate change trajectory of increased areal extent and cover (i.e. tree colonisation and range infilling). In both case studies, climate change-driven increases in tree cover and extent are occurring at the expense of wetland grasslands and the important ecosystem functions they support

Marine Vegetation Management Strategies: a framework for estuary wide prioritization of protection and rehabilitation

Intertidal systems are constrained by landscape morphology. Where these systems do occur, they often experience a wide range of anthropogenic impacts, further exacerbated by sea-level rise (SLR). By mapping natural morphological constraints, anthropogenic impacts and modeled SLR, at an estuary-wide scale the Marine Vegetation Management Strategies (MVMS) identify and prioritize sites and interventions that could address key threats and risks to the system enabling rehabilitation. Development of MVMS is part of an initiative within the broader New South Wales (NSW) state government\u27s Marine Estate Management Strategy to deliver healthy coastal habitats. The MVMS are being developed to take a policy of “no net loss of key fish habitats” toward more active management of intertidal systems that maximize and sustain the ecosystem values and services. Spatial indicators were developed for a pilot estuary (Tweed River) to map and quantify “macrophyte potential” which is defined as the capacity for macrophytes (mangrove and saltmarsh) to deliver ecosystem services now and into the future (under scenarios of SLR). The approach incorporates datasets which indicate the geophysical nature of the landscape, anthropogenic exposure, and vulnerability to SLR. This strategic science-based approach is being rolled out across coastal NSW, with the mapping products and associated resources identified as key tools to assist in the adopting of a more integrated approach to managing coastal wetlands

Representations of OxyContin in North American Newspapers and Medical Journals

Following the approval of OxyContin (Purdue Pharma, Canada) for medical use, the media began to report the use of OxyContin as a street drug, representing the phenomenon as a social problem. Meanwhile, the pain medicine community has criticized the inaccurate and one-sided media coverage of the OxyContin problem. The authors of this study aimed to contribute to an understanding of both sides of this controversy by analyzing the coverage of OxyContin in newspapers and medical journals. The analyses revealed inconsistent messages about the drug from physicians in the news media and in medical journals, which has likely contributed to the drug’s perception as a social problem. The authors suggest ways to address the lack of medical consensus surrounding OxyContin. The results of this study may help resolve the concerns and conflicts surrounding this drug and other opioids

Mangrove Response to Environmental Change in Northern Australia

Mangrove forests are critical for carbon storage, primary productivity, coastline protection and biodiversity, however have been degraded across their range. One exception is northern Australia, where mangroves are protected and undisturbed. Hence, the majority of changes can be attributed to natural events.Focusing on three areas in northern Australia (the Gulf of Carpentaria, Kakadu National Park and Hinchinbrook Island), the primary aim was to quantify changes in the extent, cover and height of mangroves over temporal and spatial scales using time-series data from airborne and/or spaceborne optical, radar and LiDAR sensors. Secondary, was to establish the reasons for changes in relation to climate, coastal inundation and sea levels. For the Gulf of Carpentaria, the mangroves exhibited progressive landward and seaward extension from 1987 to 2014. These extensions were attributed respectively to a) regular supply of sediment through freshwater input and b) combined effects of sea level rise and prolonged tidal and freshwater inundation. In Kakadu NP, maps of mangrove extent were generated using aerial photography (1991), hyperspectral (2002), LiDAR (2011) and RapidEye (2014 and 2016). Changes in the annual mangrove area between 1987 and 2012 indicated a close correspondence with sea level and river discharge. In 2015, extensive dieback of mangroves was reported in the Gulf of Carpentaria. A drone survey in Kakadu NP in September 2016 confirmed dieback had also occurred, primarily affecting landward Avicennia marina. The immediate and long-term implications of Tropical Cyclone Yasi were investigated at Hinchinbrook Island. Based on a combination of Landsat, Queensland Globe aerial imagery and RapidEye imagery, 16 % of the 13,795 ha of mangroves were found to be damaged. Damage was primarily inflicted on Rhizophora stylosa, little/no recovery was attributed to an inability of R. stylosa, to resprout and changes in hydrological and sediment regimes.This investigation observed significant changes in mangrove extent and structure. Of concern is that, mangroves showed limited recovery. Global climate projections suggest enhanced: temperatures, Sea Surface Temperatures (SSTs), storm intensities and changes in rainfall. For this reason, there is urgent need to establish baselines of extent, structure and species composition and to monitor changes

Assessing the distribution and drivers of mangrove dieback in Kakadu National Park, northern Australia

Satellite observations of Australia\u27s Gulf of Carpentaria between 1987 and 2015 highlighted that many mangroves on the coastline bounding low-lying plains were progressively extending inland and to a lesser extent, in a seaward direction. However, in 2015/16, a significant and widely publicised mangrove dieback event occurred, this was attributed to a combination of climate (temperature, precipitation anomalies) and a ~20-30 cm decline in sea level. A similar but unreported event also occurred in Kakadu National Park (NP) in the Northern Territory. This study aimed to a) quantify the extent of this dieback in the NP, b) establish the characteristics of mangroves (floristics, structure) and the substrate elevation prior to and following event and c) establish links with climate and sea level. Using time-series of high resolution airborne and Unmanned Airborne Vehicle (UAV) data, the majority of mangroves experiencing full or partial dieback were found to occur on the landward margins. Reference to sea-level data indicated that mangroves had colonised and retreated in unison with sea level fluctuations over previous decades but increased in overall extent and cover as sea level rise dominated. Mangroves experiencing full mortality were located on higher elevation substrates where the sea level/tidal influence was least. The study concluded that whilst short-term ENSO-related sea level may result in dieback in northern Australia, the long-term projection of an increase in sea level is anticipated to lead to extension of mangroves in the landward direction

Historical perspectives on the mangroves of Kakadu National Park

Mangroves are a major ecosystem within Kakadu National Park in Australia\u27s Northern Territory, providing coastal protection, high biodiversity and an important resource for Aboriginal people. In the late Holocene (from c. 6000 before present), mangroves occupied much of the estuarine and coastal plains, but their range has subsequently contracted to the main river systems (the West Alligator, South Alligator and East Alligator Rivers, and the Wildman River), tributary creeks and offshore islands (Field and Barrow Islands). On the basis of maps of mangrove extent generated from aerial photography (1950, 1975, 1984 and 1991), compact airborne spectrographic imagery (CASI; 2002), light detection and ranging (LIDAR; 2011) and RapidEye data (2014 onward), changes in net area have been minor but significant redistribution has occurred, with this being attributed to both inland intrusion and seaward colonisation of mangroves. The greatest area changes have been associated with lower-stature mangroves dominated by Avicennia marina and Sonneratia alba, as determined from these datasets. Aerial surveys, conducted using a remote piloted aircraft (RPA) and fixed wing aircraft in September 2016, showed dieback of mangroves, with spaceborne RapidEye observations suggesting this occurred between late 2015 and 2016 and at the same time as the extensive mangrove losses reported in the Gulf of Carpentaria. Given the recent dieback and the associated need to better monitor and protect mangroves and proximal ecosystems in the World Heritage- and Ramsar-listed Kakadu National Park, the study recommends the development and implementation of a robust and long-term monitoring system that better utilises existing and ongoing earth observation and ground data, and is supported by a national approach