environment
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Climate change is threatening tropical reefs across the world, with most scientists agreeing that the current changes in climate conditions are occurring at a much faster rate than in the past and are potentially beyond the capacity of reefs to adapt and recover. Current research in tropical ecosystems focuses largely on corals and fishes, although other benthic marine invertebrates provide crucial services to reef systems, with roles in nutrient cycling, water quality regulation, and herbivory. We review available information on the effects of environmental conditions associated with climate change on noncoral tropical benthic invertebrates, including inferences from modern and fossil records. Increasing sea surface temperatures may decrease survivorship and increase the developmental rate, as well as alter the timing of gonad development, spawning, and food availability. Environmental changes associated with climate change are linked to larger ecological processes, including changes in larval dispersal and recruitment success, shifts in community structure and range extensions, and the establishment and spread of invasive species. Loss of some species will trigger economic losses and negative effects on ecosystem function. Our review is intended to create a framework with which to predict the vulnerability of benthic invertebrates to the stressors associated with climate change, as well as their adaptive capacity. We anticipate that this review will assist scientists, managers, and policy-makers to better develop and implement regional research and management strategies, based on observed and predicted changes in environmental conditions.
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This introductory chapter provides an overview of the book's contents and definitions of key concepts including benthic habitat, potential habitat and seafloor geomorphology. The chapter concludes with a summary of commonly used habitat mapping technologies. Benthic (seafloor) habitats are physically distinct areas of seabed that are associated with particular species, communities or assemblages that consistently occur together. Benthic habitat maps are spatial representations of physically distinct areas of seabed that are associated with particular groups of plants and animals. Habitat maps can illustrate the nature, distribution and extent of distinct physical environments present and importantly they can predict the distribution of the associated species and communities.
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This record is a review and synthesis of geological research undertaken along the northern margin of Australia. The record has been written in support of regional marine planning and provides fundamental baseline scientific information for the Northern Planning Area.
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Physical sedimentological processes such as the mobilisation and transport of shelf sediments during extreme storm events give rise to disturbances that characterise many shelf ecosystems. The intermediate disturbance hypothesis predicts that biodiversity is controlled by the frequency of disturbance events, their spatial extent and the amount of time required for ecological succession. A review of available literature suggests that periods of ecological succession in shelf environments range from 1 to over 10 years. Physical sedimentological processes operating on continental shelves having this same return frequency include synoptic storms, eddies shed from intruding ocean currents and extreme storm events (cyclones, typhoons and hurricanes). Modelling studies that characterise the Australian continental shelf in terms of bed stress due to tides, waves and ocean currents were used here to create a map of ecological disturbance, defined as occurring when the Shield's parameter exceeds a threshold of 0.25. We also define a dimensionless ecological disturbance ratio (ED) as the rate of ecological succession divided by the recurrence interval of disturbance events. The results illustrate that on the outer part of Australia's southern, wave-dominated shelf the mean number of days between threshold events that the Shield's parameter exceeds 0.25 is several hundred days.
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This dataset contains species identifications of macro-benthic worms collected during survey SOL4934 (R.V. Solander, 27 August - 24 September, 2009). Animals were collected from the Joseph Bonaparte Gulf with a benthic sled or a Smith-McIntyre grab. Specimens were lodged at Northern Territory Museum on the 24 September 2009. Species-level identifications were undertaken by Chris Glasby at the Northern Territory Museum and were delivered to Geoscience Australia on the 26 October 2009 See GA Record 2010/09 for further details on survey methods and specimen acquisition. Data is presented here exactly as delivered by the taxonomist, and Geoscience Australia is unable to verify the accuracy of the taxonomic identifications.
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Catchment outlet sediments (0-10 cm depth, sieved to <2 mm) collected at a very low density over most of the Australian continent have been analysed using the Mobile Metal Ion (MMI®) partial extraction technique. Of the 54 elements analysed, eight are generally regarded as essential nutrients for plant growth: Ca, Cu, Fe, K, Mg, Mn, P and Zn. For these, 'bioavailability', defined here as the ratio of the partial digest concentration to the total concentration, has been investigated. This estimation of 'bioavailability' gives results comparable with standard agricultural measurements. Average 'bioavailability' ranges from 15.0% for Ca to 0.1% for Fe. Smoothed (kriged) colour contour maps for continental Australia have been produced for these eight nutrients and interpreted in terms of lithology (e.g., presence of carbonates in the MMI® Ca map), mineralization (e.g., well known and possibly less known mineral districts in the Cu, P and Zn maps), environmental processes (e.g., salinity in K map, weathering and acid generation in Fe map) and agricultural practices (e.g., application of fertilizers in P and Zn maps). This first application of a partial extraction technique at the scale of a continent has yielded meaningful, coherent and interpretable results.
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Explaining spatial variation and habitat complexity of benthic habitats from underwater video through the use of maps. Different methodologies currently used to process and analyse percent cover of benthic organisms from underwater video will be addressed and reviewed.
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Moreton Bay (MB) is a large (~1800 square km), stressed (with recent outbreaks of the cyanobacteria Lyngbia majscula), sub-tropical estuary which receives urban and rural runoff from a large catchment. Silicon is an essential nutrient for diatomaceous phytoplankton growth in coastal ecosystems. BSi (biogenic silicon) in surface sediments, pore water DSi (dissolved silicate, SiO4--) and benthic DSi fluxes were used as tracers of the formation and degradation of organic matter (OM) in MB. This work has implications for N & P cycling, water quality and eutrophication. BSi, TOC (both up to 2 wt%), TN & TP and diatom sterol biomarkers were all highest in the muddy sediments of western MB that is ~65% of the bay's area. We found that diatoms dominated OM cycling in western MB, and the benthic DSi flux accounted for ~80% of the pelagic productivity. Our conceptual model is that diatoms being heavy (because of their Si content) sink rapidly to the sediments where their biomass-N (OM-N) was denitrified to N2 and lost to the atmosphere with an efficiency of about 50%. Approximately 60% of OM-P, subsequent to degradation, remained trapped within the sediment. Diatoms therefore are an important vector to repeatedly deliver river-borne N & P to their respective sinks. However, diatomaceous OM contributed only about 20% of the OM input to the marine sands of eastern MB, about 34% of the bay's area. The principal OM input to the sandy sediments was attributed to benthic photosynthesis and N-fixation with rates of N-fixation (estimated from pore water DIN gradients) at 1.5 - 3.5 mmol m-2d-1. OM was rapidly and efficiently degraded (principally by O2), with little net accumulation and burial in sediments. N was denitrified efficiently (~100%). DIP must have been recycled rapidly in the top few cm's of the sandy sediments to support N-fixation. A whole-bay silicate budget indicated that: 1. DSi fluxes through the western margin of MB were about 4- fold those in eastern MB. 2. Pelagic diatom productivity was supported (approximately) by the benthic fluxes of DSi. 3. The DSi inventory was recycled through diatomaceous phytoplankton in about 15 days. 4. The export of DSi to the sea was about the same as the combined terrestrial and small marine inputs.
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From 1995 to 2000 information from the federal and state governments was compiled for Comprehensive Regional Assessments (CRA), which formed the basis for Regional Forest Agreements (RFA) that identified areas for conservation to meet targets agreed by the Commonwealth Government with the United Nations. This CD was created as part of GA's contribution to the Central Highlands CRA. It contains final versions of all data coverages and shapefiles used in the project, Published Graphics files in ArcInfo (.gra), postscript (.ps) and Web ready (.gif) formats, all Geophysical Images and Landsat data and final versions of documents provided for publishing.
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There is growing awareness of the scientific and intrinsic value of Antarctic geological features, including sites containing rare, and in some cases, globally unique mineral occurrences, mineral assemblages, and unusual rocks features (e.g. ventifacts) and rare fossils. However, the global economic value of the mineral and fossil trade is also considerable and growing, with prized specimens being sold for prices per gram equivalent to that of gold. Locations of geological value, once considered 'protected' by virtue of the logistical complexity and prohibitive cost involved in collection, are becoming increasingly vulnerable as the interest of collectors grows and the inaccessibility of Antarctica diminishes with more frequent visits by private and adventure travellers. Thus the need for proactive intervention, protection and management of 'geo-heritage' sites is becoming increasingly urgent. Wider recognition of the geological values of sites achieved by invoking the provisions for area management of the Madrid Protocol will also help mitigate casual souveniring and accidental or deliberate damage caused by ill-advised construction or other human activity, such as use of heavy machinery.