B1 Selection of Critical Services, Components and Processes
B1.1 Methods – Information Collation and Review Stage
The first step in ECD preparation outlined in the National Framework document is to identify the wetland services/benefits, wetland components and wetland processes present in the Ramsar site. These key terms are defined in Section 1 of the Report and the Glossary (refer Section 9). This was initiated by undertaking a process of information collation and literature review.
As part of the information collation phase, literature and existing data relevant to the study area (site boundary and surrounds) were collated and reviewed. Relevant existing information was sourced from the following:
published scientific papers
database records (EPBC Protected Matters Search Tool, Parks Australia databases, etc.)
quantitative data (bird count data, etc.)
mapping products supplied by Parks Australia (vegetation and wetland mapping)
management plans, strategies and other policy documents, and
grey literature from internet searches and other sources of data.
Each article of information was collated to a cursory level sufficient to determine its relevance to the study. The collected information was then reviewed to prioritise and identify information of direct relevance to the ECD.
As part of the information collation phase, key information sources to be used in the study were presented to the project Steering Committee and gaps were identified on the basis of these reviews. In some cases, additional information was supplied directly by Steering Committee representatives.
B1.2 Methods – Selection of Critical Components, Process and Services/Benefits
Following the information collation and review phase, the study team collectively identified the relevant components, processes and services/benefits of the wetland. This process was based primarily upon a review of the literature and professional opinion. Using the categories and list of components, processes and services/benefits from the National Framework as a guide, it was apparent that the Kakadu National Park Ramsar site provides a broad spectrum of components, processes and ecosystem services/benefits. This included: provisioning services such as provision of traditional foods, regulatory services such as erosion protection and water quality maintenance, cultural services such as recreational fishing and hunting, tourism, cultural heritage, education and research and supporting ecosystem services such as biodiversity and the presence of endangered and vulnerable species.
Likewise, given the scope, areal extent and diversity of wetland environments present within the Kakadu National Park Ramsar site, all wetland components and processes from the National Framework were seen as occurring within the site, including a broad range of hydrological, climatic, geomorphologic, physico-chemical, biogeochemical and biological processes. It was noted that while each of these processes play a part in underpinning normal wetland functioning, some of these factors such as coastal hydrodynamics and climate also operate at both regional scales and local scales.
As outlined in Section 2, a range of wetland habitat types are known to be present within the site boundaries including those designated within the coastal/marine, inland and man-made wetland categories under the Ramsar classification scheme. Within these systems, a rich diversity of wildlife exists from all the major groups of organisms (from planktonic organisms to vertebrates) which make up the components of the wetland.
With the full range of ecosystem components, processes and services/benefits represented, there was a need to identify the most important or critical in the context of the Ramsar site. Following the method within the National Framework, the assignment of a given wetland process, component or service/benefit as critical was determined with reference to the following criteria:
the component, process or service/benefit is an important determinant of the uniqueness of the site, or is widely accepted as representing a particularly outstanding example of an environmental value supported by the site
the component, process or service/benefit is important for supporting one or more of the Ramsar Nomination Criteria under which the site was listed, and
a change to the component, process or service/benefit would result in a fundamental change in ecological character of the site.
To supplement the criteria from the National Framework, additional consideration was given to suggestions or recommendations regarding critical services, components or processes by the Steering Committee and Knowledge Management Committee (particularly where such information was also documented in scientific literature). Accordingly, a set of draft critical services/benefits were presented to the Knowledge Management Committee at its meeting in August 2009 and minor revisions made as part of this process.
In addition to critical components, processes and services/benefits, a range of other elements were identified as being important to the maintenance of the morphological, physio-chemical and biological processes. These ‘supporting’ components, processes and services/benefits, while important to wetland functioning, were in isolation were not considered to directly address the criteria listed above. For example, a change in water quality (a supporting process) would not itself be considered to result in a change to ecological character. While changes to a supporting element may result in an ecological response, it is considered that such changes would be adequately captured through assessment of LACs for critical components, processes or services/benefits.
Justification for inclusion of critical and supporting components, processes or services/benefits is provided in the body of this report.
In selecting key species/groups that underpin critical components, processes and services/benefits, the following methods were considered:
B1.3.1 Flora Species
In nominating particular wetland flora species or communities for consideration under the critical components, the following considerations were applied:
species should generally occur in aquatic environments (for example, macrophytes) or are otherwise considered to be wetland-associated species or communities, and
species or communities should be listed as threatened (i.e. vulnerable or endangered) at the National (threatened under EPBC Act) and/or International (IUCN) level or are considered to be particularly noteworthy or critical from a regional biodiversity perspective (refer to Nomination Criterion 3). This includes species or communities that are perceived by the authors to be iconic to the site, or are designated as threatened under Northern Territory legislation (endangered or vulnerable at a State/Territory scale).
B1.3.2 Fauna Species
In nominating particular fauna species/groups for consideration under the critical components, the following considerations were applied:
Species should generally occur in aquatic or marine environments or are otherwise considered to be wetland-dependent terrestrial species (refer Glossary in Section 9 for definitions of these terms and Appendix C for list of species).
Species should be either:
Designated as threatened (for example, endangered or vulnerable) at a national scale (under the EPBC Act) or international scale (under IUCN Red List), or
Particularly noteworthy or critical from a regional biodiversity perspective (refer to Nomination Criteria 3 or 7). This includes species that are perceived by the authors to be iconic to the site, or are designated as threatened under Northern Territory legislation (endangered or vulnerable at a State/Territory scale).
Given the boundaries of the Ramsar site are largely confined to near-shore areas or internal waters, emphasis has been placed on inclusion of those species that use the site as core habitat, have significant population numbers and spend a large proportion of their life cycle within the site boundaries. This excludes vagrant species of conservation significance such as whales, sharks and migratory seabirds that may only occur in the Ramsar site infrequently but for which species records within the site exist.
Populations of wetland biota that form the critical components are more generic groupings that recognise the abundance and diversity of animals that utilise the various wetland habitats of the site. This includes for example, amphibians, reptiles, mammals, fish, birds and aquatic invertebrates.
B2 Derivation of Limits of Acceptable Change
Limits of Acceptable Change were derived using a staged approach as follows:
determine values of the site. These represent the critical components (Section 3.3) and services/benefits (Section 3.7)
identify critical processes underpinning site values. These are the critical processes, and are outlined in Section 3.5 of the report
describe patterns in natural variability in critical components, processes and services/benefits indicators. Variability in indicators is described in Sections 3.3, 3.5 and 3.7 of the report
define the relative magnitude of acceptable change. The relative magnitude of acceptable change was determined on the basis of (i) an assessment of criticality of the site to the maintenance of species populations or habitats, based on known or likely patterns in geographic distribution, abundance and criticality of the site to maintaining the survival of a species; (ii) patterns (short-term and long-term) in natural variability; and (iii) a qualitative assessment of the vulnerability of changes outside bounds of natural variability, and
derive specific limits of acceptable change. The broad relative magnitude of acceptable change definitions was used to describe specific limits of acceptable change.
The specific values of the site was determined on the basis of (i) known or likely patterns in the distribution and abundance of species and habitats that comprise the critical services/ benefits and components of the site, and (ii) expert opinion and or empirical data describing the criticality of the site to maintaining the survival of a species. Three levels of criticality were derived based on these factors (Least, Moderate and Highest Concern), as described in Table B-1 below.
Table B-1 Categories describing importance of the site to maintaining habitats and species that underpin the critical services/benefits and components
Distribution and criticality to populations
Widespread globally and nationally, life-history functions supported in many areas elsewhere (species).
High diversity feature (habitat and community descriptor).
Habitat specialist with disjunct and very limited number of populations globally and nationally (species).
May be widespread nationally or regionally but is a critical breeding, staging or feeding site that is critical to survival of population (habitat and species).
Limited to bioregion but found in numerous basins, and is not known to be critical to survival of a species (habitat and species).
Limited to bioregion, found in a small number of basins and has limited distribution in the site (species).
Where least concern = 1 (green), of concern = 2 (yellow), most concern = 3 (orange)
The relative magnitude of acceptable change was then determined based on:
The categories describing site values/importance described in Table B-1 above.
Whether species/habitats that underpin the critical components or services/benefits are known or likely to be highly sensitive/intolerant to changes in environmental conditions.
Known/likely patterns in natural temporal variability of indicators in the short-term (based on inter-annual cycles or episodic disturbance) and long-term (based on processes operating over time scales measured in decades). Three broad categories were adopted to describe variability at the two temporal scales (inter-annual and decadal):
Highly variable: greater than 60 percent change
Medium variable: ten to 60 percent change, and
Stable: less than ten percent change.
A high level qualitative assessment of the consequences associated with changes in parameters outside natural variability was undertaken. Five consequence categories were derived, and are based in part on general risk categories developed by the SCFA – FRDC Project Team (2001) for the Risk Assessment Process for Wild Capture Fisheries (Version 3.2) (refer Table B-2).
Consideration of patterns in natural variability, site values/importance and the consequence ratings for assessing sensitivity to change were used to derive three relative magnitude of acceptable change categories: (i) no change; (ii) small change; (iii) moderate to large change. These are shown in Table B-3.
Table B-2 Defining impact magnitude
Mortality likely local extinction.
Total ecosystem collapse.
Mortality may affect recruitment and capacity to increase.
Measurable impact to functions, and some functions are missing/ declining/ increasing outside historical range and/or facilitate new species to appear.
Mortality within some spp. Levels of impact at the maximum acceptable level.
Measurable changes to ecosystem components but no loss of functions (no loss of components).
Affected but no impact on local population status (e.g. stress or behavioural change to individuals).
Keystone species not affected, minor changes in relative abundance.
Possible changes, but inside natural variation.
Table B-3 Relative magnitude of acceptable change categories for LAC indicators