Glossary M – P

|  M  |  N  |  O  |  P  |

M


Macroalgae

Macroalgae ('seaweeds') are an ancient class of large multicellular plants that resemble vascular plants but lack the complex array of tissues used for reproduction and water transport. More information


Macroinvertebrates

Benthic macroinvertebrates are organisms that live on the bottom of a water body (or in the sediment), have no backbone and are >50 cm in length.


Macrotidal

Coastal ocean or waterway with a high mean tidal range, e.g. greater than 4 metres.


Mangroves

Mangroves comprise several species of trees and shrubs that grow along sheltered intertidal shores, mainly in tropical & subtropical coastal waterways. More information


Marine pests

Marine pests are introduced species that threaten human health or environmental and economic values. More information


Marine Protected Areas

Marine Protected Areas are areas of sea that are dedicated to the protection and maintenance of biodiversity and natural and cultural resources. They are Commonwealth reserves under the EPBC Act. More information


Matters for target

Matters for target are broad themes within the National Monitoring and Evaluation Framework against which reports are made using a range of indicators and report cards. These broad themes include land salinity, soil condition, native vegetation communities' integrity, Inland aquatic ecosystems' integrity (rivers and other wetlands), estuarine, coastal and marine habitats' integrity, nutrients in aquatic environments, turbidity/suspended particulate matter in aquatic environments, surface water salinity in freshwater aquatic environments, significant native species and ecological communities, and ecologically significant invasive species. More information


Maturity Index

The "maturity index" of an estuary is the ratio of the present water surface area (Ap), to its palaeo-water area (Ao) referenced to around 6,500 years before present, when sea level achieved its present position. More information


MERI Framework

Commonly used abbreviation for the Natural Resource Management Monitoring, Evaluation, Reporting and Improvement Framework.


Mesotidal

Coastal ocean or waterway with a moderate mean tidal range, e.g. between 2 and 4 metres.


Metal Adsorption

The adherence of one substance (atoms, ions or molecules) to the surface of a solid substance with which is has been brought in contact.


Metal contaminants

Metal contaminants comprise metals and metalloids found in concentrations that exceed national guidelines. More information


Micro community

An assemblage of species within a facies that depend on facies member species. Many landscape managers assume that conservation of the facies will generally safeguard the conservation of associated micro communities [1].

  1. Butler, A., P. Harris, et al. (2001). An Interim Bioregionalisation for the continental slope and deeper waters of the South-East Marine Region of Australia., National Oceans Office.

Microinvertebrates

Microinvertebrates are microscopic invertebrates ( < 10 mincrons) that live on the bottom of a water body (or in the sediment) and have no backbone.


Microtidal

Coastal ocean or waterway with a low mean tidal range, e.g. less than 2 metres.


Monitoring

Monitoring is regular gathering of information, and the preliminary analysis of this information, in order for for day-to-day management or evaluation. More information


Mouth

The entrance of the coastal waterway, or the place where the sea meets or enters the coastal waterway.


Mud

Fine sedimentary material, typically comprising both inorganic (mineral) and organic material.


Multi(ple) Criteria Analyses

Multi(ple) Criteria Analyses are methods for weighting and aggregating data, and prioritising options and alternatives.


Multibeam Sonar or Swath Echosounders

A multibeam sonar is an echo sounder which transmits a wide acoustic pulse which extends to either side of the ship, in a manner similar to a sidescan sonar. The receive transducer array resolves the returning signal into numerous beams, recording two-way travel time, and angle of arrival for each beam. In this way, accurate depth soundings (or bathymetry) are achieved for the entire swath. The accuracy of a multibeam sonar is critically dependant on corrections applied for vessel motion (e.g. pitch, roll, yaw, heave), and spatial location, which is achieved by a highly accurate global positioning system (GPS). Consequently, multibeam sonars require real time integration with a number of other specialist sensor systems. Various multibeam sonars are appropriate for use in a range of water depths and environments. High resolution systems (over 400 kHz) can achieve < 1 cm vertical resolution, have over 200 very narrow beams (around 0.5°) and swath widths of approximately 3 - 4x water depth in shallow water (~50 m). Conversely, low-frequency systems are available that can be used in great depths (e.g. several km), however these have lower resolution and much larger beam 'footprints'. Multibeam sonar systems can also provide 'backscatter' information (e.g. reflected sound intensity) in a manner similar to a sidescan sonar, which is useful for determining seabed character.

Back to top of page


N


NAP

the commonly used abbreviation for National Action Plan for Salinity and Water Quality.


National

An adjective describing something that is produced or agreed by jurisdictions at all levels including the Australian Government, State/NT Governments, NRM Regions and Local Governments.


National Action Plan for Salinity and Water Quality

The National Action Plan for Salinity and Water Quality (NAP) is a commitment by the Australian, state and territory governments to jointly fund actions tackling major NRM issues facing Australia's rural industries, regional communities and our unique environment. It supports practical remedies such as improvements to native vegetation, engineering works, the protection and rehabilitation of waterways and land and water use changes. More information


National Estuarine Environmental Condition Assessment Framework (NEECAF)

A framework for reporting on the broad ecological integrity of estuaries at a national level, developed and adopted by regions states/territories and the Australian Government.


National Estuaries Network

The National Estuaries network (NEN) evolved during the first NLWRA out of a recognized need for an organized network for coastal managers to exchange knowledge and keep up-to-date with scientific research. The bi-annual NEN forums are now a key mechanism for linking estuarine decision makers and scientists. More


National Intertidal/Subtidal Benthic Habitat Classification Scheme (NISB)

The National Intertidal/Subtidal Benthic Habitat Classification Scheme (NISB) was designed to support the production of maps for the purpose of representing areas of marine and coastal habitats at the national scale [1,2]. The scheme is hierarchical and initially divides habitats according to broad substrate type, and then according to whether they are spatially dominated by "structural macrobiota" (SMB) or by the substrate (i.e. largely "bare" of visible biota) [1,2].

National Intertidal/Subtidal Benthic Habitat Classification Scheme

Figure 1. National Intertidal/Subtidal Benthic Habitat Classification Scheme

References

  1. Mount, R.E. and P.J. Bricher, 2008a. Estuarine, Coastal and Marine (ECM) National Habitat Mapping Project, Project Report, Version 1 February 2008. Spatial Science Group, School of Geography and Environmental Studies, University of Tasmania. Report to the Department of Climate Change and the National Land and Water Resources Audit, Canberra, ACT
  2. Mount, R.E. and P.J. Bricher, 2008b. Estuarine, Coastal and Marine (ECM) National Habitat Map Series User Guide Version 1 February 2008. Spatial Science Group, School of Geography and Environmental Studies, University of Tasmania. Report to the Department of Climate Change and the National Land and Water Resources Audit, Canberra, ACT.

National Land and Water Resources Audit

The National Land and Water Resources Audit (the Audit or NLWRA) was funded by the Australian Government through the Natural Heritage Trust. It was set up in 1997 to improve land, water and vegetation management by providing better information to resource managers. The Audit ended on 30 June 2008.


National Monitoring and Evaluation Framework (NM&EF), Australian

The National Monitoring and Evaluation Framework (NM&EF) was established in 2002 to assess the health of Australia's land, water and biological resources, and the performance of NHT/NAP (and other) government programs. More information


National outcomes, NRM

National outcomes are aspirational statements about a desired national natural resource result. More information


Native vegetation

Native vegetation is defined as vegetation that is indigenous to a given state, including trees, shrubs, understory plants and some specified grasslands. More information


Natural Heritage Trust

The Natural Heritage Trust (the Trust) was established by the Australian Government in 1997 to help restore and conserve Australia's environment and natural resources. More information


Natural Resource Management Monitoring, Evaluation, Reporting and Improvement Framework

The Natural Resource Management Monitoring, Evaluation, Reporting and Improvement Framework (MERI Framework) is a broad, overarching document that provides a generic framework for monitoring, evaluating, reporting on and improving Australia’s approach to managing key assets. More


Nautical Mile

A nautical mile (M) is a unit of distance equal to 1,852 metres. More information


Neap Tide

Tide smaller than the mean tidal range. Occurs about every two weeks, during half-Moons.


Near-pristine estuaries

What are Near-Pristine Estuaries?

Roughly half of Australia's estuaries were classified as "near-pristine" during the National Land and Water Resources Audit (NLWRA). Near-pristine estuaries are estuaries that have not been impacted upon by humans in significant ways, and are considered to exist in an essentially natural state. This means that the estuaries are not used for aquaculture, that fishing is limited and sustainable and that the water movements through the estuaries and fringing wetlands have not been altered by roads or engineering structures ( e.g. training walls, causeways and barrages). In addition, the catchments of near-pristine estuaries retain most of their natural vegetation cover. As the catchments of near-pristine estuaries are not heavily urbanised nor used for large-scale farming, we assume that the amounts of sediment and nutrients that are delivered to these estuaries in stream flow are near the levels they would be if European-style living and farming practices had never been introduced to Australia. By implication, near-pristine estuaries tend to be located along the most remote and inaccessible parts of the coastline. We tend to know little about Australia´s near-pristine estuaries because they are mainly found in these out of the way places.

This webpage is a central starting point for gaining an overview of Australia's near-pristine estuaries. It includes two useful clickable maps that:

Physical Characteristics Condition
Catchment natural cover >90%
Land use Limited roads and disturbance to natural conditions and processes
Catchment hydrology No dams or impoundments, virtually nil abstraction
Tidal regime No impediments to tidal flow, changes from natural morphology (e.g. Training walls, barrages, bridges and causeways)
Floodplain Wetlands intact in vegetation and hydrology, no alterations to flood pattern
Estuary use Extractive activities limited to indigenous or limited and sustainable commercial and recreational fishing, no aquaculture
Pests and weeds Minimal impact on estuary from catchment weeds and limited pests and weeds within estuary
Estuarine ecology Ecological systems and processes intact (e.g. benthic flora and fauna)

Table 1. The criteria used by the NLWRA to define a near-pristine estuary.

Map of Australia´s near pristine estuaires and their condition based on the NLWRA assessment 2002

Figure 1. The condition of estuaries around Australia based on the NLWRA assessment 2002.

Back to top of page


Why the Interest in Near-pristine Estuaries?

Why the interest in near-pristine estuaries? In the first place, near-pristine estuaries are a valuable part of Australia´s natural heritage. They are important as undisturbed habitat for native plants and animals, and for biodiversity conservation, tourism and fisheries. In addition, by studying near-pristine estuaries, scientists can learn more about natural systems and the ways that human activities have caused them to change. This information then feeds into natural resource management because it constitutes benchmark or baseline information against which similar information from more modified estuaries can be compared. It is also worth mentioning that most countries do not have nearly as many near-pristine estuaries as Australia, and thus may lack this important opportunity for conservation and scientific inquiry.

Back to top of page


Aims and Context of the Comparative Geomorphology of Estuaries Project

The central aim of the Comparative Geomorphology of Estuaries Project in the Coastal CRC was to improve our understanding of Australia’s near-pristine estuaries. As the title implies, the project had a geomorphic focus in that a major output was mapping of geomorphic habitats of a representative selection of near-pristine estuaries from around Australia. In the coastal context, geomorphic habitats are landforms (´geo´-´morph´) such as salt marshes and intertidal flats whose shape and position in the landscape are strongly governed by the effect of physical and biological forces on sediments. The mapping follows on from similar work undertaken during the National Land and Water Resources Audit (NLWRA), when the geomorphic habitats of 540 of Australia´s estuaries were mapped (Heap et al., 2001 [PDF 17.4Mb]). However, near-pristine estuaries were poorly represented in the NLWRA process because they were slated for protective management only. Consequently, only 41 near-pristine estuaries were mapped.

Back to top of page


Project Achievements and Findings
(see the pdf file 0.6Mb)

158 new geomorphic habitat maps of near-pristine estuaries

The geomorphic habitats of 158 near-pristine estuaries were mapped in Comparative Geomorphology of Estuaries Project. The maps are available for down-load in the query the database function in OzCoasts database where they exist alongside the maps of near-pristine and modified estuaries generated during the NLWRA.

The near-pristine estuaries that were mapped in this project were chosen to reflect, as far as possible, the full range of geomorphic variability in Australia: A statistically significant number of the different types of estuaries (between 16 and 26) were chosen, and these were spread as far as practicable around the Australian coastline. Within this context, state preferences and the availability of suitable images and photographs were also taken into account. By estuary types, we refer to the major kinds of coastal waterways ( i.e. wave- and tide-dominated estuaries and deltas, tidal creeks, strandplains and embayments) which experience differing amounts of wave-, tide- and river energy. Each coastal waterway type has a characteristic distribution of different habitats (for example fluvial or bayhead deltas, tidal sand banks, or intertidal flats), and these are depicted conceptually in a report by Ryan et al ., 2003 [PDF 3.9Mb] and in the conceptual models component of OzCoasts.

Near-pristine estuaries from Queensland and the Northern Territory comprised by far the largest proportion of the estuaries mapped during the project, accounting for 46% and 30% respectively. Significantly fewer estuaries were mapped in Tasmania (9%), New South Wales (2%) and Victoria (<1%). This was mainly because there are far fewer near-pristine estuaries in these southern states (see figures 1 and 3), and many of them had already been mapped during the NLWRA. The national set of habitat maps in OzCoasts now includes near-pristine examples of Australia 's diverse estuaries and coastal waterways.

Click on each region in the figure below for a summary of the typical characteristics of estuaries for that region.

characteristics of the Great Australian Bight near-pristine estuaries

Figure 2. The coastal geomorphic regions of Harris et al., 2002 [PDF 1.1Mb] and the estuary geomorphic types (Heap et al., 2001 [PDF 17.4Mb]).

A State by State breakdown of estuaries according to condition classification (based on NLWRA data).

Figure 3. A State by State breakdown of estuaries according to condition classification (based on NLWRA data).

Back to top of page


A Literature Review on Australia´s Near-Pristine Estuaries

(see the pdf file 1.7Mb)

The purpose of the literature review was to collate previously disparate information on near-pristine estuaries, and make it widely available for use by managers, researchers and the general public. This information was acquired through scientific articles, reports, conference proceedings, government agencies, grey literature, web-sites, expert advice and anecdotal observation, and was summarised both on a state-by-state basis and at the national level, with emphasis on current knowledge and management.

The extent and availability of information pertaining to near-pristine estuaries was generally good at the catchment level in most states. Information at the individual estuary level was patchier, although important geomorphic, water quality and ecological studies have been undertaken. An unfortunate finding of the literature review was that a reasonably large percentage of the estuaries deemed to be in near-pristine condition during the NLWRA will likely have to be re-classified to account for modification in either the catchment or in the estuary itself. The occurrence of aquaculture was often cited as the cause for re-classification of estuaries in the southern states, while over-looked catchment modification was the main reason for changes to classifications in Northern Australia . The downstream impacts of cattle grazing on the near-pristine estuaries in northern Australia in particular, is unknown and could be quite extensive.

Land management practices were found to vary greatly across Australia . The catchments of near-pristine estuaries in the southern states are often fully contained within National Parks, while there was a mixture of land tenure in the northern catchments (indigenous, pastoral lease, crown land and freehold) and fewer national parks. Inclusion of the catchments of near-pristine estuaries in National Parks ensures that the estuaries are managed for conservation, and are afforded some measure of protection against future development. This adds to the conservation significance of the estuaries in the framework of a National Representative System of Marine Protected Areas (NRSMPA). With this purpose in mind, tables were provided in each state chapter in which the near-pristine estuaries were assigned to their appropriate coastal IMCRA regions (Interim Marine and Coastal Regionalisation for Australia) to help with future NRSMPA programmes. All IMCRA regions in Queensland , Northern Territory and northern Western Australia had near-pristine estuaries, and the IMCRA regions of Tasmania were reasonably represented by near-pristine estuaries (see figure 4). There are 14 IMCRA regions with no near-pristine coastal waterways along the NSW, VIC, SA and southern WA coastlines.

Click on each state/territory for a close up map of the IMCRA bioregions and geomorphic type of the near-pristine estuaries in that state/territory.

IMCRA bioregions from IMCRA, and the geomorphic type of near-pristine  estuaries around Australia according to the NLWRA assessment

Figure 4. IMCRA bioregions from IMCRA, 1998 [PDF 1Mb], and the geomorphic type of near-pristine estuaries around Australia according to the NLWRA assessment (Heap et al., 2001 [PDF 17.4Mb]).

Back to top of page


Remote Sensing Techniques & Applications to Near-Pristine Estuaries

(see the pdf file 3.7Mb)

Remote sensing involves the collection of information about the earth's surface, using sensors mounted on satellites or airplanes. The result of remote sensing is an image from which the spatial distribution of different landscape characteristics ( e.g. mangrove forests and seagrass beds) can be mapped. Remote sensing has been used for many years to map the coastal zone both for research and management purposes. One relevant example was the use of aerial photography to map Australia 's coastal geomorphic habitats during the NLWRA. However, it was underscored in the remote sensing methods and applications portion of the Comparative Geomorphology of Estuaries Project that more advanced satellite and /or airborne remote sensing instruments are now available, and these can be even more cost effective and objective than air photo interpretation. This is because the imagery can be collected at larger spatial scales (regional) and because computer software is now available that can help automate the process by which classified maps are made from the images.

Back to top of page


Indicators of Estuary Environmental Condition based on the GIS Maps of Estuary Geomorphic Habitats

(see the pdf file 0.5Mb)

In a preliminary study, we compared the areas of different habitats of the various types of Australian estuaries on the basis of the NLWRA environmental condition classifications. The results were very encouraging. We found systematic changes in estuary geomorphic indicators with diminishing estuary environmental condition (i.e. from near-pristine, through largely unmodified and modified to severely-modified) for most types of estuaries (e.g., Figure 5). The estuaries that were more disturbed by native vegetation clearance in catchments and development in and around the estuaries had higher levels of geomorphic maturity. This finding indicates that these types of environmental disturbances appear to result in a relatively greater load of sediment moving into the estuary. This was evidenced in apparent increases in the areas of tidal sand banks, intertidal flats and mangroves in tide-dominated estuaries, and in intertidal flats in wave-dominated estuaries. The wave-dominated estuaries also appear to have experienced a marked reduction in salt marsh areas. Our results suggest that higher sediment loads resulting from land clearing have led to pre-mature infilling of some Australian estuaries.

The results of this study thus highlight the potential of the national estuary geomorphic habitat area dataset for providing new insights into the way estuaries react to changes in catchment land use. This is especially the case for many estuaries for which there is a lack of useful historical records.

Some preliminary results for the geomorphic indicator analysis of Tidal Creeks

Figure 5 . Some preliminary results for the geomorphic indicator analysis of Tidal Creeks. These box and whisker diagrams show medians, 25th and 75th percentiles and ranges for the relative area data of the various geomorphic habitats. Environmental condition classifications are: near-pristine (NP); largely unmodified (LM); modified (MOD); and severely modified (SM). Note there are reasonable trends in most of the data.

Back to top of page


References

  1. Murray, E., Radke, L., Brooke, B., Ryan, D., Moss, A., Murphy, R., Robb, M and Rissik, D. 2006. Australia's near-pristine estuaries: Current knowledge and management. Cooperative Research Centre for Coastal Zone, Estuary & Waterway Management Technical Report #63.
  2. Creasey, J., Dyall, A., Ticehurst, C., Rogers, B., Radke, L., Brooke, B., Ryan, D., Heap, A., Murray, E. and Dekker, A. 2006. Improving our knowledge of Australia's near-pristine estuaries: Geomorphic habitat mapping and related applications – Final Report. Cooperative Research Centre for Coastal Zone, Estuary & Waterway Management Technical Report #64.
  3. Radke, L., Brooke, B., Ticehurst and E. Murray. 2006. Major achievements of the Comparative Geomorphology of Estuaries project. Cooperative Research Centre for Coastal Zone, Estuary & Waterway Management Technical Report #65.
  4. Radke, L., Brooke, B., Ryan, D. Lahtinen, A. and Heap, A. 2006. An initial assessment of estuarine geomorphic indicators of coastal waterway health – Final Report. Cooperative Research Centre for Coastal Zone, Estuary & Waterway Management Technical Report #66.
Characteristics of the Gulf of Carpentaria near-pristine estuaries Characteristics of the northeast near-pristine estuaries Characteristics of the southeast coast near-pristine estuaries Characteristics of the southwest coast near-pristine estuaries Characteristics of the northwest coast Pilbara region near-pristine estuaries Link to conceptual models home page Characteristics of the Great Australian Bight near-pristine estuaries IMCRA regions of Tasmania with a list of near-pristine estauries IMCRA regions of Victoria with a list of near-pristine estuaries IMCRA regions of New South Wales with a list of near-pristine estuaries IMCRA regions and near-pristine and largely unmodified estuaries of South Australia IMCRA regions and near-pristine estuaries of central and southern Western Australia IMCRA regions of the Northern Territory with a list of near-pristine estuaries IMCRA regions of the western Cape York Peninsula with a list of near-pristine estuaries IMCRA regions of the Kimberley Region with a list of near-pristine estuaries IMCRA regions and near-pristine estuaries of East Queensland

NEECAF

Commonly used abbreviation for the National Estuarine Environmental Condition Assessment Framework.


Negative Estuary

An estuary in which evaporation exceeds freshwater inflow and therefore hypersaline conditions exist.


NEN

Commonly used abbreviation for National Estuaries Network.


Nephelometry

Nephelometry is a kind of turbidity measurement in which the intensity of light scattered by a sample is compared with the intensity of light scattered by a standard reference suspension under the same conditions. More information


N-Fixation

Conversion of N2 gas to a form that is available for use by organisms.


NHT

Commonly used abbreviation for the Natural Heritage Trust.


NISB

Abbreviation for National Intertidal/Subtidal Benthic Habitat Classification Scheme.


Nitrification

Nitrification or 'ammonium oxidation' is a two-step respiratory process occurring in sediment (benthic nitrification) or the water column (pelagic nitrification) in which bacteria oxidise ammonium (NH4) to nitrite (NO2) and nitrate (NO3).

(Eq. 1) NH4+ + 1.5O2 = NO2- + H2O + 2H+
(Eq. 2) NO3- + 0.5O2 = NO3-

Nitosomonous spp. and Nitrobacter spp. are the main organisms responsible for steps (Eq. 1) and (Eq. 2) respectively. Nitrification exerts an important influence on marine primary productivity because:

  1. Henriksen, K, and Kemp, W.M. 1988. Nitrification in Estuarine and Coastal Marine Sediments, pp. 207-249 in T.H. Blackburn and J. Sorensen (eds.), Nitrification in Estuarine and Coastal Marine Sediments. Nitrogen Cycling in Coastal Marine Environments, John Wiley and Sons Ltd.
  2. Berounsky, V.M. and Nixon, S.W. 1990. Temperature and the annual cycle of nitrification in waters of Narragansett Bay. Limnology and Oceanography 35, 1610-1617.

Nitrate

Nitrate is a dissolved (oxidised) nitrogen species with an empirical formula of NO3-. It consists of a central nitrogen atom surrounded by three identical oxygen atoms. More information


Nitrite

Nitrite is a dissolved (oxidised) nitrogen species with an empirical formula of NO2-. More information


Nitrogen fixation, biological

Biological nitrogen fixation is the reduction of dinitrogen (N2) to ammonia (NH3). The reaction can be represented as:

N2 + 3H2 = 2NH3

The process is catalysed by the enzyme nitrogenase and is conducted by a large range of nitrogen-fixing bacteria such as Rhizobium and cyanobacteria. A broad range of environmental and biochemical factors can affect the nature and extent of nitrogen fixation within a particular environment or system. Light, water temperature, pH, salinity, dissolved oxygen, trace elements, inorganic nitrogen and organic substrate availability have all been shown to modulate nitrogenase activity in specific situations [2].

  1. Postgate, J.R. 1998. Nitrogen Fixation. 3rd Edition. Canbridge University Press, London.
  2. Capone, D.G. 1988. Benthic Nitrogen Fixation. In: Blackburn, T.H. and Sorensen, J. (eds.) Nitrogen Cycling in Coastal Marine Environments, pp. 85-123. Wiley & Sons, New York.

NLWRA

A commonly used abbreviation for the National Land and Water Resources Audit.


Non-point Sources

A source of sediment or nutrients that is not restricted to one discharge location.


NOX

NOX refers to the sum total concentration of oxidised forms of nitrogen in a sample. Those oxidised forms of nitrogen include nitrite (NO2-) and nitrate (NO3+). More information


NRM

NRM is a the commonly used abbreviation for Natural Resource Management


NRM regions

The Australian Government, in association with state and territory governments, identified 56 regions covering all of Australia in order to facilitate the integrated delivery of Natural Resource Management (NRM). NRM is delivered via the integrated implementation of the National Action Plan for Salinity and Water Quality and the Natural Heritage Trust, and relies on the cooperation of governments at all levels. More information


NRM toolbar

The NRM Toolbar comprises online tools and databases that simplify the process of finding and sharing NRM information. Once downloaded (http://www.nrmnavigator.net.au/home), the NRM Toolbar provides a single point of access to the NRM Search Engine. It was designed by the Knowledge for Regional NRM programme at Land & Water Australia.


Nutrients

Nutrients are the essential building blocks for plant and animal growth. They comprise nitrogen (N) and phosphorus (P), as well as metals, such as copper, zinc and chromium, when present at low concentrations (micronutrients). More information

Back to top of page


O


Ocean Acidification

Ocean acidification is the reduction of the pH of the world's oceans due to higher CO2 concentrations in the atmosphere. More information


Organic Material

Once-living material (typically with high carbon content), mostly of plant origin. More information.


Optically Stimulated Thermoluminescence Dating (OSL)

When quartz grains are buried, they begin to accumulate a trapped-charge population that increases in a measurable and predictable way in response to the ionising radiation to which the grains are exposed. Exposure to sunlight releases the light-sensitive trapped charge, thereby resetting the OSL signal: this process is commonly referred to as ‘bleaching'. The time elapsed since sediment grains were last exposed to sunlight can be determined by measuring the OSL signal from a sample of sediment, determining the De that this represents, and estimating the rate of exposure of the grains to ionising radiation since they were buried [1,2]. The latter parameter of interest is termed the dose rate (Dr) and the burial age of well-bleached grains may be obtained from the following equation:

Burial age (years) =

         De (Gy)        
Dr (Gy year-1)

(Gy = gray, where 1 Gy = 1 J/kg)

When clean quartz grains are exposed directly to sunlight, the OSL signal is reduced to a negligible level within a few seconds [2,3]. However, incomplete or non-uniform bleaching is commonplace in many depositional environments [4], due to surface coating on grains and/or poor exposure to sunlight during sediment transport. This results in grains being deposited with a heterogeneous distribution of residual trapped charge and a correspondingly wide range of measured De values. For such sediments, Olley et al. [5,6] suggested that the population of grains with lowest measured De values provides the most accurate estimate of Db: the burial dose to which those grains that were well bleached at deposition have been exposed since the most recent transport event.

  1. Huntley D.J., Godfrey-Smith D.I., Thewalt M.L.W., 1985. Optical dating of sediments. Nature 313, 105-107.
  2. Aitken, M.J., 1998. An Introduction to Optical Dating: The Dating of Quaternary Sediments by the Use of Photon-stimulated Luminescence. Oxford University Press, Oxford.
  3. Wintle, A.G., 1997. Luminescence dating: laboratory procedures and protocols. Radiation Measurements 27, 769-817.
  4. Murray, A.S., Olley, J.M., 2002. Precision and accuracy in the optically stimulated luminescence dating of sedimentary quartz: a status review. Geochronometrica 21, 1-16
  5. Olley, J.M., Caitcheon, G.G., Roberts, R.G., 1999. The origin of dose distributions in fluvial sediments, and the prospect of dating single grains of quartz from fluvial deposits using optically stimulated luminescence. Radiation Measurements 30, 207-217.
  6. Olley, J.M., Pietsch, T., Roberts, R.G., 2003. Optical dating of Holocene sediments from a variety of geomorphic settings using single grains of quartz. Submitted to Geomorphology

Author

Jon Olley, CSIRO Land and Water


The Oil Spill Response Atlas (OSRA)

The Oil Spill Response Atlas, maintained by the Australian Maritime Safety Authority (AMSA). This dataset comprises digital mapping of a wide variety of coastal features and attributes, including shoreline type (landform) mapping which has been used in preparation of the Smartline coastal landform map.


Oxidation-Reduction Reactions

Oxidation-reduction or 'redox reactions' involve a transfer of electrons, and cause changes in the oxidation state of both the reactants and the products. Oxidation is the loss of electrons and reduction is the gain of electrons. Redox reactions are important in marine systems because the chemical properties of many elements change depending on their oxidation state: for example sulphate (SO42-) and hydrogen sulfide gas (H2S) formed by sulfate reduction have very different physical, chemical and ecotoxological properties.The redox condition of a solution is usually expressed in terms of pE, which is dimensionless, or Eh which is measured in volts.

Back to top of page


P


Particulate Nitrogen (PN)

Comprises nitrogen compounds associated with or a constituent of mineral particles and organic material. More information.


Particulate Organic Matter

Particulate organic matter (POM) is organic matter that is retained on a 0.45 µm sieve. It consists of living organisms (phytoplankton, bacteria and animals) and detritus (e.g. biogenic material in various stages of decomposition). POM may be coarse or fine in size: coarse particulate organic matter (CPOM) is larger than 1 mm; and fine particulate organic matter (FPOM) is smaller than 1 mm.


Partitioning

Partitioning refers to the transfer of solutes (including contaminants such as heavy metals) between different phases and biological components (benthos and plankton) in natural waters. Solid phases include bottom sediments and suspended sediments and soluble phases refer to dissolved species in the water column.


Particulate nitrogen

Particulate nitrogen consists of nitrogen in plants and animals, and their remains, as well as ammonium (NH4+) adsorbed onto mineral particles. More information


Particulate phosphorus

Particulate phosphorus consists of phosphorus in plants and animals, and their remains, phosphorus in minerals (e.g. fluorapatite) and phosphate adsorbed onto iron oxyhydroxides on mineral surfaces. More information


Pathogen

A pathogen is a causative agent of disease. Microbial pathogens are microscopic organisms including bacteria, viruses, protozoa and fungi. More information


Pelagic Fish

Pelagic fish are fish that live in the water column.


pH

pH is a measure of acidity or alkalinity of water on a log scale from 0 (extremely acidic) through 7 (neutral) to 14 (extremely alkaline). It is the negative base-10 log of the hydrogen ion (H+)activity in moles per litre. More information


Photosynthesis

Photosynthesis, primary production, carbon production or simply 'production' is the process whereby pigments such as chlorophyll a in plants and algae capture sunlight and covert it to organic matter and oxygen. Plankton generally has a Redfield molar proportion (e.g. C106H263O110N16P1). Therefore photosynthesis by phytoplankton can be represented by the following reaction [1]:

106CO2 + 16 NO3- + HPO42- + 122H2O + 18H+ + (solar energy, trace elements) = C106H263O110N16P1 + 138O2

A maximum photosynthetic rate (P-max) is attained when an increase in light level no longer causes an increase in production rate (Figure 1).

Pmax is the maximum photosynthetic rate. It is achieved at a certain light level for which any increase in light does not increase the production rate. However, a decrease may occur due to high light levels and is called photoinhibition (Contributed by Samantha Wellman, University of Newcastle).

Figure 1. Pmax is the maximum photosynthetic rate. It is achieved at a certain light level for which any increase in light does not increase the production rate. However, a decrease may occur due to high light levels and is called photoinhibition (Contributed by Samantha Wellman, University of Newcastle).

  1. Drever, J.I. 1982. The Geochemistry of Natural Waters, Prentice-Hall, Inc., Englewoods Cliffs, N.J., pp. 388.

Phosphate

Phosphate is a dissolved inorganic species of phosphorus with an empirical formula of PO43-. It is often reported as filterable reactive phosphorus or FRP. More information


Phytoplankton

Microscopic, planktonic plants which exist within the water column.


Piscivorous Fish

Piscovorous fish are fish that feed on other fish.


Planktivorous Fish

Planktivorous fish are fish that feed on plankton.


Point Sources

A source of sediment or nutrients that is restricted to one discharge location.


Precipitation

A chemical reaction in which a previously dissolved substance forms an insoluble solid substance which drops out of solution (i.e. precipitates).


Pressures, causal pressures

In Natural Resource Management, causal pressures are the driving forces behind changes in waterways. Causal pressures often result from human activities and uses, although natural climate change and natural disasters can also constitute causal pressures or ecosystem forcing functions. More information


Pristine estuaries

See Near-pristine estuaries


Prograde

The outward building of a sedimentary deposit, such as the seaward advance of a delta or shoreline.


Prograding Coastlines

Coastal regions in which water has withdrawn from parts of the land surface due to a fall in sea level relative to the land are called prograding coastlines.


Pyrite Oxidation

Pyrite (FeS2) is an iron sulfide mineral that is formed through the process of sulfate reduction. Pyrite is stable under anoxic conditions. However, on exposure to air, a mole of pyrite oxidises to form 2 moles of sulfuric acid in a 3 step reaction [1]:

(Eq. 1) FeS2 + 7/2O2 + H2O = Fe2+ + 2SO42- + 2H+
(Eq. 2) Fe2+ + 1/4O2 + 3/2H2O = FeOOHppt + 2H+
(Eq. 3) FeS2 + 15/4O2 + 7/2H2O = Fe(OH)3ppt + 2SO42- + 4H+

Aluminium and Iron Mobilisation

The sulfuric acid formed in sulfate reduction may then react with clay minerals to release silica and metals of which aluminum (Al3+), iron (Fe2+), potassium (K+), sodium (Na+) and magnesium (Mg2+) are most abundant [1]:

(Eq. 4) (K0.5N0.36Ca0.05)(Al1.5Fe0.25Mg0.3)(Al0.45Si3.46)O10(OH)2 + 7.41H+ + 2.59H2O = 0.5K+ + 0.36Na+ + 0.05Ca2+ + 0.3Mg2+ + 0.25Fe(OH)3 + 1.95Al3+ + 3.46H4SiO4

Manganese and metal contaminants may also be released in the process [1].

  1. Sammut, J., White, I., Melvilles, M.D. 1996. Acidification of an estuarine tributary in eastern Australia due to drainage of acid sulphate soils, Marine and Freshwater Research 47, 669-684.

Back to top of page