Neil Tindale

Coupling between ocean biota and atmospheric aerosols: Dust, dimethylsulphide, or artifact?

[1] Two hypotheses that postulate interactions between ocean biota and aerosols in the atmosphere have generated substantial research into marine systems. The stimulation of phytoplankton photosynthesis by the provision of iron, a micronutrient contained in deposited aeolian dust (the Iron Hypothesis), and the contribution of dimethylsulphide (DMS) produced by marine ecosystems to the atmospheric burden of aerosols (the CLAW Hypothesis) have been the focus of much research. Satellite sensors, such as the Seaviewing Wide Field-of-view Sensor (SeaWiFS) now provide moderate-resolution time series of measurements of the optical properties of the oceans and atmosphere over most of the Earth’s surface. These data provide an unprecedented opportunity to investigate the ubiquity of biotic linkages between the ocean and atmosphere at the global scale. We analyzed 5 years of SeaWiFS 8-day fields of two variables, chlorophyll concentration and aerosol optical depth, for the global oceans. This first global, multiyear approach does not yet allow unequivocal conclusions, as satellite measurements of chlorophyll can be influenced by aerosol properties of the atmosphere and several variables we do not yet examine are likely to play a role. We find correlation between optical properties of the ocean and atmosphere over much of the globe, in particular the midlatitudes. While some regional analyses indicate that SeaWiFS chlorophyll retrievals are biased by dust in the atmosphere, our results do not support the existence of widespread bias in the SeaWiFS products, but are consistent with global-scale couplings posited by the Iron and CLAW hypotheses.

Evaluation of Pathogen Removal in a Solar Sludge Drying Facility Using Microbial Indicators

South East Queensland is one of the fastest growing regions in Australia with a correspondingly rapid increase in sewage production. In response, local councils are investing in more effective and sustainable options for the treatment and reuse of domestic and industrial effluents. A novel, evaporative solar dryer system has been installed on the Sunshine Coast to convert sewage sludge into a drier, usable form of biosolids through solar radiation exposure resulting in decreased moisture concentration and pathogen reduction. Solar-dried biosolids were analyzed for selected pathogenic microbial, metal and organic contaminants at the end of different drying cycles in a collaborative study conducted with the Regional Council. Although fecal coliforms were found to be present, enteroviruses, parasites, E. coli, and Salmonella sp. were not detected in the final product. However, elevated levels of zinc and copper were still present which restricted public use of the biosolids. Dilution of the dried biosolids with green waste as well as composting of the biosolids is likely to lead to the production of an environmentally safe, Class A end-product.

Faecal sterols analysis for the identification of human faecal pollution in a non-sewered catchment.

In this study, faecal sterols were used to identify human faecal pollution in a non-sewered catchment in Southeast Queensland, Australia. In all, 36 water samples were collected from six sites on six occasions and the concentration of sterols were determined using gas chromatography and mass spectrometry. The stanols concentration in water samples generally increased with increased catchment runoff. After moderate rainfall, high coprostanols levels found in water samples indicated human faecal pollution via defective septic systems. In contrast, it appears that during dry weather human faecal pollution is not occurring in the study catchment. Sterol profiles also pointed to a cattle farm polluting during modest catchment runoff. The method used in this study was able to identify the sources of faecal pollution to the catchment due to rainfall.

A systematic approach for modelling quantitative lake ecosystem data to facilitate proactive urban lake management

BackgroundThe management of the health of urban lake systems is often reactive and is instigated in response to poor aesthetic quality or physicochemical measurements, rather than from an overall assessment of ecosystem health. Interpreting physicochemical monitoring data in isolation is problematic for two main reasons: the suite of parameters that are monitored may be limited; and the contribution that any single parameter has towards water quality or health varies considerably depending on the nature of the system of interest. Extending monitoring programs to include flora and fauna results in a better dataset of ecosystem status, but also increases the complexity in interpreting whether the status is good or poor.ResultsThis paper details a process by which a large set of quantitative biological, physical, chemical and social indicators may be transformed into a simple, but informative, numerical index that represents the overall ecosystem health, while also identifying the likely source and scale of pressure for remedial management action. The flexibility of the proposed approach means that it can be readily adapted to other lake systems and environments, or even to include or exclude different indicators. A case study is presented in which the model is used to assess a comprehensive longitudinal dataset that resulted from monitoring a constructed urban lake in Southeast Queensland, Australia.ConclusionsThe sensitivity analysis and case study indicate that the model identifies how changes in individual monitoring parameters result in changes in overall ecosystem health, and thus illustrates its potential as a lake management tool.

Community well-being as a critical component of urban lake ecosystem health

Urban lakes are often monitored and managed with limited consideration of adjacent communities. Generally, when communities are considered in relation to urban lakes, they are viewed simply as sources of pollutants. Given the inevitable interactions between an urban lake and the surrounding inhabitants, the community must be considered explicitly when assessing the ecosystem health of urban lakes, as the two entities intrinsically comprise interrelated parts of a single ecosystem. In this study, the reciprocal links between a residential community and a series of urban lakes in South East Queensland have been examined to facilitate a dynamically linked, fully integrated ecosystem health assessment of constructed urban lakes. Residents’ attitudes towards, and values derived from, a series of urban lakes were surveyed, as well as residents’ behaviours which may impact upon urban lake health. The results indicate that residents derive both tangible and intangible benefits from the urban lakes, but feel little responsibility for lake health or custodianship over the lakes. Greater recognition within urban lake management frameworks of the links between urban lake systems and their surrounding communities may help to foster and enhance both community well-being, a greater sense of custodianship for such systems and improved management.

GIS as a Rapid Decision-support Tool for Raptor Conservation Planning in Urbanising Landscapes

Abstract Rapidly transforming landscapes are places in which biodiversity loss is likely. Where urbanisation is rapid, conservation planners are often unable to afford the necessary time to adequately gather data and assess threats to biodiversity. Better methodologies are required to inform decision making about development assessments and conservation planning. This paper argues for adopting GIS (geographic information systems) that incorporate available scientific and community-based data and scenarios modelling within the policy framework, to derive geographic surrogates and impact surrogates for conservation planning. This methodology is applied to a pilot study of raptors on the Sunshine Coast, Australia, and evaluates its efficacy. Preliminary results suggest that, while there are some limitations, this methodological approach offers useful insights to conservation planning. Other key findings imply that current planning frameworks are insufficient to protect raptors in this area. Non-remnant vegetation was an important habitat at the regional scale; while the importance of the ‘sustainable caneland’ precincts was demonstrated for most species, including critical species. In the Sunshine Coast, both of these habitats are vulnerable to future urban development.

Reforestation of agricultural land in the tropics: The relative contribution of soil, living biomass and debris pools to carbon sequestration

Tropical regions of the world experience high rates of land-use change and this has a major influence on terrestrial carbon (C) pools and the global C cycle. We assessed land-use change from agriculture to reforested plantings (with endemic species), up to 33 years of age, using 10 paired sites in the wet tropics, Australia. We determined the impacts on 0-50 cm below-ground C (soil organic C (SOC), charcoal C, humic organic C, particulate organic C, resistant organic C), C stored in roots (fine and coarse), C stored in living above-ground biomass and debris C pools. Reforested areas accumulated ecosystem C at a rate of 7.4 Mg ha-1 yr-1. Reforestation plantings contained, on average, 2.3 times more ecosystem C than agricultural areas (102 Mg ha-1 and 233 Mg ha-1, respectively). Most of the C accumulation was in living above-ground and below-ground biomass (60 and 30%, respectively) with a smaller amount in debris pools (16%). Apart from C in roots, soil C accumulation was not obvious across sites ranging from 8 to 33 years since reforestation, relative to the agricultural baseline. Differences in SOC (and associated SOC pools) to a depth of 50 cm, did exist between reforested areas and adjacent agriculture at some sites, however there was not a consistent trend in SOC associated with reforestation. Local site-based factors (e.g. soil texture and mineralogy, land-use history and microbial activity) appear to have a strong influence on the direction of the change in SOC. While reforestation in the tropics has great potential to accumulate C in biomass in living vegetation, and debris pools, it is likely to take approximately 50 years before C stocks of reforested areas resemble natural ecosystems. Accumulation of SOC through reforestation is difficult to achieve, highlighting the need to conserve carbon pools in remnant forests in the tropics.