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Critical Services/Benefits

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3.7Critical Services/Benefits

The present study identifies three critical services/benefits for the Kakadu National Park Ramsar site (Table 3 -10). In the context of the nomenclature outlined by the Millennium Ecosystem Assessment (2003), critical services/benefits for the site are classified as follows:


  • S1 – Maintenance of Global Biodiversity, which is considered to represent a supporting service.

  • S2 – Fisheries Resource Values, which can be considered to represent cultural, supporting or provisioning services.

  • S3 – Contemporary Living Culture, which can be considered to represent a cultural service.

3.7.1S1 – Maintenance of Global Biodiversity


Reasons for Selection as ‘Critical’

Biological diversity, or biodiversity, is the variety of all life forms, the genes they contain and the ecosystem processes of which they form a part. The term biodiversity can therefore incorporate most of the critical and supporting components outlined in the previous sections. However, in the context of how the Ramsar site provides a critical role in maintaining global biodiversity, two critical components together have been selected in the context of this critical service:



  • supporting critical habitat for globally and nationally threatened wetland-dependent species, and

  • supporting critical habitat for locally endemic species.

These two critical components are also important in their own right. The role of the site in maintaining threatened wetland fauna species underpins Ramsar Nomination Criterion 2, and was identified by Fox et al. (1977) as justification for National Park declaration (refer Fox et al. 1977). Endemic species form a key element of biodiversity, as recognised in Section 70 of Ramsar Convention Secretariat (2007), which underpins Ramsar Nomination Criterion 3.

In addition to the values of these species in terms of maintaining global biodiversity, some species are of great scientific research value (see Section 3.7.1), provide a cultural resource (for example, pig-nosed turtle, see Section 3.7.3) and/or play a role in maintaining wetland ecosystems and foodwebs (see general account in Section 3.5.5).


Description

Five globally or nationally threatened species are considered to have critical habitat within the Ramsar site (Table 3 -17). Several other threatened species are also known or likely to occur in the site, however the site is not considered to represent critical habitats for these species (see Section 2.5.2). The role of the wetlands within the Ramsar site in maintaining these species, together with patterns in variability, are described in other sections relating to critical components and processes (see Table 3 -17).



Refer to Section 3.2.11 (Critical Component C11) for an account of locally endemic invertebrate species within the Ramsar site.
Table 3 17 Threatened wetland species that have critical habitats within the Ramsar site

Species

Reproduction

Recruitment

Feeding

Population

Critical Element

Northern river shark

Unknown.

Yes – neonates and juveniles appear to be restricted to estuaries.

Yes – turbid rivers.

Small, highly fragmented population globally (New Guinea and Australia). South, East and West Alligator Rivers, and three other localities external to the Ramsar site, support this species (Compagno et al. 2008).


C8

Speartooth shark

Unknown but possible.

Yes – neonates and juveniles restricted to upper estuary.

Yes – turbid rivers.

Small, highly fragmented population globally (New Guinea and Australia). East and South Alligator Rivers are two of the five known Australian localities supporting this species (Compagno et al. 2008).

C8

Pig-nosed turtle

Yes – nest on river banks.

Yes.

Yes – particularly billabongs

Breeding populations in Australia are known in the East and South Alligator Rivers, with two other known localities external to the site and a number of other anecdotal reports (Doody et al. 2000). Also occurs as isolated population in New Guinea (Cogger & Heathcote 1981).

C10

Flatback turtle

Yes – critical nesting site.

No.

No.

Field Island represents one of six major nesting sites in Australia, and has been identified as a habitat critical to the survival of this species.

P4

Yellow chat

Yes.

Yes.

Yes.

Small geographic area encompassing the floodplains from the Adelaide River to the East Alligator River, (Woinarski et al. 2007). Total population size estimated to be about 500 breeding birds (Garnett and Crowley 2000) and Kakadu National Park sub-population probably around 300 (Armstrong 2004).


C9

Freshwater and dwarf sawfish

Possibly - Freshwaters of large river systems.

Possibly - Freshwater and upper estuaries.

Yes.

Both have a wide geographic distribution but highly fragmented, and thought to be uncommon where they occur. Freshwater sawfish recorded in eight catchments within Northern Territory, including South and East Alligator Rivers (Peverell et al. 2006). Population size unknown. Dwarf sawfish recorded in five catchments, including South Alligator River (Peverell et al. 2004)

N/A

Green turtle and dugong

No.

No.

Some feeding – but not core area.

Limited area of feeding habitat (intertidal seagrass) within the site is not critical to maintaining populations of these species at even a local scale.

N/A

Blue shading – site is not known to be a critical habitat for this species

3.7.2S2 – Fisheries Resource Values

Reasons for Selection as ‘Critical’

Kakadu National Park supports important fisheries resources in the form of fisheries habitats. This was selected as a critical service/benefit due to fisheries values being an important determinant of the site’s unique character, and the importance of fisheries values with respect to support of other services/benefits including recreation and tourism (supporting service) and contemporary living culture (Service 3). This service/benefit is based on fisheries habitat and fish abundance, and excludes fishing activities.

In the context of this service, barramundi Lates calcarifer has been selected as a key indicator of the fisheries habitat values of the site. Selection of barramundi as a key indicator is based on a number of reasons: recreational fishing focuses almost entirely on this species, has been relatively well-studied and also represents a key traditional food species together with other cultural values (refer Section 3.7.3). Habitat values and patterns in the abundance of barramundi are discussed below.

3.7.2.1Habitats


Description

All wetland types together support the ecosystems and constituent habitats, populations and food webs that support fisheries resource values within and adjacent to the site. Commercial fishing is banned throughout the site and no recreational fishing is allowed upstream of the Kakadu Highway, except on Jim Jim, Muirella Park and Sandy Billabongs, and Yellow Water. Fishing is also prohibited on the West Alligator River and some other billabongs. Due to the wide home range of many estuarine and marine species, the site is also likely to support habitats and other fisheries resources that contribute to fisheries productivity outside the site.

Most commercially important species, including barramundi, use a wide range of habitats (and habitat patches) as part of their life-cycle. It is therefore appropriate to consider fisheries habitat values in the context of:


  • the range habitat types supporting different life-history functions of different fisheries species (and their prey, for example, bony bream, mullet, rainbowfish etc.)

  • hydraulic (flow regimes) and bio-physical habitat conditions, which ultimately control patterns in fish community structure across a range of spatial and temporal scales

  • connectivity/linkages between different habitat types and patches, which vary seasonally

  • specific environmental conditions and stresses within particular habitat patches (for example, water quality conditions), and

  • biological interactions (particularly predation, prey availability) within particular habitat types and patches.

Patterns in Variability

In the context of describing natural variability in fisheries resource values, the following habitat characteristics have been selected as indicators:


  • area of floodplain, billabongs, mangrove, saltmarsh, intertidal flat habitats (bio-physical habitat indicators)

  • estuary length, perimeter and area, and

  • annual flow volumes (broad hydraulic habitat indicator).

Section 3.3 describes patterns in natural variability in the extent/distribution (where known) of seagrass, mangroves, intertidal flats, monsoon rainforest supported by springs, permanent waterholes and seeps in stone country, Melaleuca forest, and palustrine wetlands and billabongs.

The additional habitat indicators considered in the context of this service are floodplain area and estuary length, perimeter and area (refer Table 3 -18). Note that the estuary indicators are for the maximum, dry season extent of the estuary. Flooding (during the wet season) often results in the estuary retracting to near the river mouth within the South Alligator River (Vertessy 1990), and most likely in the other catchments. However, following flood recession, salt propagates upstream such that by the end of the dry season, sea water salinities are attained near the tidal limit of the South Alligator River (Vertessy 1990).


Table 3 18 Key catchment, estuary and flow descriptors for each catchment within Kakadu National Park



Parameter

Catchment




East Alligator

South Alligator


West Alligator

Wildman

Catchment area (km2)B

15 871

11 921

2228

2476

Maximum estuary length (km)B

64.3

78.52 (103 km)

28.02

32.31

Maximum estuary perimeter (km)B

164.3

172.7

58.82

66.2

Maximum estuary area (km2)B

92.47

105.2

9.43

4.37

Mean annual rainfall (mm/yr)B

1379

1363

1396


Mean annual flow (ML/yr)B

6 870 000*

5 750 000**

815 000***

Mean annual runoff (mm/yr)B

601

555

566

B = NLWRA (2001), taken to mean the upstream extent of saltwater influence (dry season)

Mean annual flow from: * Gauge Stations G821010 and G821009; ** Gauge station G820112; *** Gauge station G819001.


With the exception of a study by Hess and Melack (2003) which had limited spatial and temporal context, there are few empirical data describing patterns in variability in estuary size and floodplain inundation area within the site. However, in qualitative terms, it is known that floodplains of the site are a hydrologically dynamic habitat. During the annual wet season, the underlying clay soils are flooded by 10 to 200 centimetres of water, while during the dry season they are dry and deeply cracked. The annual wetting and drying cycle is a reliable occurrence, but the timing of wet season onset, and the extent and duration of inundation are not (see Section 3.5.1). Maintenance of the seasonal flooding regime is critical to the maintenance of aquatic foodwebs and wetland ecosystem functioning (Douglas et al. 2005; see Section 3.5.5). River flow dynamics, and patterns in variability, are described in Section 3.5.1 of this report.

3.7.2.2Barramundi Abundance


Description

Recreational fishing within the site is based almost entirely on barramundi. The maximum allowable catch is two fish per day per person (Director of National Parks 2007). Under the Northern Territory Fisheries Act 2005, Indigenous people may fish by traditional methods in traditional areas, and are otherwise subject to the same controls as recreational fishers. The catch by Indigenous people in the Northern Territory was estimated to be 44 134 barramundi in 2000 (Coleman et al. 2003), however the contribution of the site to this total catch has not been quantified.

There are insufficient recent data to determine key fishing areas and fish production within the site. However, creek surveys undertaken in 1986-1987 between Darwin and East Alligator River indicated that South Alligator River and East Alligator River ranked second and third respectively to Mary River in terms of recreational fishing effort (approximately 29 percent and 10 percent of total effort, respectively) and catch (approximately 9000 fish in South Alligator River in 1986) (Griffin 1989). Notably, compared to a survey done in 1978-1979 using the same methods, recreational effort had increased by approximately 27 percent and catch by approximately five percent (Griffin 1989). However, it is likely that recreational fishing effort has increased markedly since the 1986-1987 survey due to the increase in visitor numbers to the Park (refer Section 3.8.1).

In the context of this critical service, Kakadu National Park is an important breeding, recruitment and feeding site, as well as dry season refugia. Barramundi ecology is strongly influenced by fluvial hydrology and tidal processes (Pusey et al. 2004). In addition to its role in controlling geomorphology and therefore habitat structure, freshwater flows and tidal processes ultimately control spawning, feeding and abundance patterns during all life-cycle stages (Pusey et al. 2004). The catchments of the site have a large river discharge and low catchment gradient (and associated high residence time of fluvial flows), which together with the relatively undisturbed condition of floodplain habitats, provide the necessary conditions for maintaining high barramundi abundances (Pusey et al. 2004).

Spawning occurs in estuarine creek mouths, with spawning sites typically in areas with low tidal current velocities (Pusey et al. 2004). The on-set of spawning is thought to occur immediately prior to the wet season, and is thought to be linked to water temperature (Pusey et al. 2004). Barramundi are tolerant of a wide range of water quality conditions (i.e. salinity, dissolved oxygen, turbidity). However local fish kills can occur in drying water holes in response to high water temperatures and low dissolved oxygen concentrations (Pusey et al. 2004), as well as after rainfall when deoxygenated, nutrient enriched waters flow into waterholes. Barramundi is not known to have a highly selective diet, but does vary according to age (small invertebrates and small fish as juveniles, fish, prawns, crabs as adults) (Pusey et al. 2004). Prey items can be strongly influenced by flows and water quality conditions.


Patterns in Variability

The key indicator in the context of this critical service is barramundi abundance. Barramundi abundance has been assessed at Yellow Water billabong in September 1990 by Griffin (1994). Griffin (1994) suggested that the population was comprised of approximately 6000 individuals at that time, with catch per unit effort (CPUE) of 3.8 fish per 100 metre net per hour. At Corroboree Billabong on the Mary River, the CPUE was 6.7 fish per 100 metre net per hour.

Long-term fish monitoring studies by eriss provide standardised, empirical fish catch data from two sandy bed billabongs located in Nourlangie Creek (Sandy Billabong) and Magela Creek (Mudginberri Billabong) sub catchments (based on visual census techniques – see Humphrey et al. 2005). Over the monitoring period 1994 to 2005, the mean overall number of barramundi recorded per 50 metre (using the visual boat census technique) was 0.987 individuals per 50 metres at Mudginberri Billabong, and 0.283 individuals per 50 metres at Sandy Billabong (see Section 3.2.6).

There are no available data describing patterns in barramundi abundance over time or within other areas of the Ramsar site.


3.7.3S3 – Contemporary Living Culture

Reasons for Selection as ‘Critical’

Contemporary living culture was selected as a critical service as it is an important determinant of the site’s unique character. In particular, it is noteworthy that the Kakadu National Park Ramsar site meets all four of the Ramsar cultural characteristics as outlined by Resolutions VIII.19 and IX.21 (cultural characteristics ‘a’, ‘c’ and ‘d’ described below; refer Section 3.8.3 for cultural characteristic ‘b’).


Description

Bininj within Kakadu National Park undertake cultural and land management practices, follow customary law and uphold traditions established over thousands of years of continuous occupation. Kakadu National Park’s contemporary ‘living culture’ is described under three of the Ramsar cultural characteristics below.

Maintenance of the living culture is dependent on factors such as land ownership, access to land and resources, transmission of cultural knowledge and practices to younger generations, protection of sites and documentation of cultural heritage.

Cultural characteristic ‘a’: Sites which provide a model of wetland wise use, demonstrating the application of traditional knowledge and methods of management and use that maintain the ecological character of the wetland.

The management of Kakadu National Park provides a model of wetland wise use, incorporating traditional knowledge and providing a balance between competing interests such as nature conservation and tourism. Kakadu National Park’s model of joint-management between Bininj and the Australian Government is renowned on a worldwide scale for its success in its integration of Bininj and western management techniques, as well as its recognition of Indigenous land rights and self-determination (de Lacy 1994).


Sustainable Use

Bininj and Parks Australia have developed a successful system of wise-use whereby Bininj can sustainably harvest native plants and animals within the national park. This system is critical in maintaining Bininj cultural heritage as Traditional Ecological Knowledge is transferred (for example, harvesting techniques, species’ ecology), Bininj languages are used, other cultural practices are undertaken while harvesting traditional foods, and land management is often undertaken simultaneously. Resources that are harvested may be used for food, art and craft, medicine and other customary uses, as described in further detail below. Bininj continue to hold detailed knowledge of the usage, availability and ecology of hundreds of plant and animal species (Brockwell et al 1995).


Threat Management

Bininj knowledge has assisted Parks Australia in monitoring and managing threats to the Ramsar site, thereby maintaining the ecological character. For example, feral buffalo were causing extensive environmental damage during the 1960s through vegetation destruction, soil compaction, weed dispersal, habitat modification and erosion (see Higgins 1999, Director of National Parks 2007). Bininj and local community members established a buffalo control program to reduce buffalo numbers, and started to restore wetlands in the 1970s. Bininj traditional ecological knowledge regarding the original state of the environment, the impact of buffalo and the management and restoration of wetlands was central to the successful restoration of the wetlands (D. Lindner pers. comm. 2009).


Cultural characteristic ‘c’: Sites where the ecological character of the wetland depends on the interaction with local communities or Indigenous peoples.

Through historical and current practices, Bininj have influenced, and continue to influence, the ecological character of the Kakadu National Park Ramsar site. Bininj hold a substantial body of traditional ecological knowledge which includes topics such as fire, species, ecosystems, ecological processes, landscape change and seasons. A joint management arrangement enables Bininj to look after Kakadu National Park in cooperation with National Park staff, providing opportunities for relevant Bininj to be consulted, make decisions and implement these in the management of Kakadu National Park. As such, the application of traditional ecological knowledge and cultural knowledge in land management, cultural heritage management and tourism contributes towards maintaining the ecological character of the wetlands and surrounds.

Bininj and the local community have been working with Parks Australia North on natural resource management programs since the inception of Kakadu National Park. Approximately 30 percent of the staff employed through Kakadu National Park are Bininj people with 20 percent having a close connection to Kakadu National Park or the region (S. Winderlich pers. comm. 2009). Bininj and the local community have also initiated a number of programs over the years to deal with threats to Kakadu National Park’s ecological character, notably Mimosa pigra control, restoration of billabongs at Gina and Yellow Water, fencing for protection of cultural sites and the re-establishment of floodplain burning (information provided through Kakadu National Park ECD Workshop Jabiru 2009).


Fire Management

Fire management is a particularly important interaction that influences the ecological character of the Ramsar site. Archaeological records reveal an increase in charcoal and a change in vegetation after the arrival of Bininj, suggesting that fire was being actively managed by humans and was consequently having a significant impact on the environment (Hiscock and Kershaw 1992). Fire was an important tool for expressing ownership, for managing food resources, as a hunting strategy, for clearing grasses and undergrowth to make travel easier, for communication, for defence and for specific spiritual and cultural obligations (Russell-Smith 1995, Director of National Parks 2007). For example, wetland burning has transformed Boggy Plain from a dense monoculture of grass to a mosaic of diverse habitats rich in resources. The Boggy Plain project has assisted in passing on Traditional Ecological Knowledge to younger generations.

The present vegetation communities and suites of fauna are dependent on the traditional burning practices established by Bininj over a long period of time (Director of National Parks 2007, Russell-Smith 1995). Bininj work with Parks Australia to develop fire management strategies and annual burning plans that replicate traditional burning (Director of National Parks 2007, also see Section 3.5.2).

Cultural characteristic ‘d’: Sites where relevant non-material values such as sacred sites are present and their existence is strongly linked with the maintenance of the ecological character of the wetland.

In some cultures, belief systems do not differentiate between the economic, social, cultural and spiritual value of wetlands and people seem to have a more holistic perspective of their world. Indigenous people in Australia consider themselves an integral part of their natural environment. With the poorest soils of any inhabited continent and with a very dry climate, the high productivity of Australia’s wetlands has given them special significance for these people. Their wetlands are very often sacred to them: they are story places and evidence of the work of the ancestral creators who made the landscape and provided for the needs of people. This holistic perspective is also found in many indigenous belief systems in Africa and the Americas.


The spiritual connection between people and wetlands has a long history and is still of great significance today in many cultures, their belief systems and traditions representing an important feature of wetland cultural heritage – and at the same time often ensuring the conservation and wise use of wetlands.’ (Ramsar Convention Secretariat 2002).

The Kakadu National Park landscape is overlain by a complex spiritual and social system sustained by Bininj. Bininj believe that the natural features in the current landscape reflect the journey and actions of the first people, the Nayuhyunggi. The living essence of some of these first people remains in the land, and as such all land is valuable under this spiritual perspective, with some sites viewed as particularly sacred or significant (Chaloupka 1993). Further information regarding culturally significant sites is provided in Section 3.8.5 below.

Sites of cultural significance are important to the maintenance of the ecological character of Kakadu National Park, as many of these sites must remain undisturbed in order not to disrupt the powers of the creation ancestors residing within. Many sites need to be cared for and some even require the practice of increase ceremonies to ensure that the plants, animals and people of Kakadu National Park prosper.




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