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Cape York Peninsula Land Use Strategy
Cape York Peninsula Land Use Strategy
Abrahams, H., Mulvaney, M., Glasco, D., & Bugg, A.
Office of the Co-ordinator General of Queensland
Australian Heritage Commission, March 1995
The mangrove communities of eastern Queensland including Cape York Peninsula have been widely studied; for example Dowling and McDonald (1979), Bunt (1982), and Duke (1992) and as part of the CYPLUS NRAP program Danaher (1994). Mangrove areas are important for their ecological role, as these marine plants directly support local and off-shore fisheries through the provision of food, shelter and breeding areas (Danaher 1994).
Duke (1992) provides the global context for the Australian mangrove communities. Mangrove communities are richest in tropical regions with sea temperatures being an important determinant of distribution. The eastern coastline of continents with warmer ocean currents have larger areas, wider distributions and richer mangrove communities than the western coasts with colder off-shore currents.
Similarly species richness generally reduces with distance from the tropics, and this is certainly the case along the east coast of Australia, Cape York Peninsula having over 30 species recorded compared with nine in South East Queensland, and one in Victoria (Duke 1992). As a result many species reach their limit of range progressively further south along the coast.
The mangrove flora of Australasia is one of the richest in the world having around five times greater species diversity than all other regions with the exception of southern New Guinea (Duke 1992). The Cape York Peninsula mangrove communities are therefore among the richest in the world and exhibit a strong zonal pattern (Danaher 1994). Duke (1992) discusses the known disjunctions of mangrove communities in the region which provides an indication of the biogeographic history of mangrove communities. The current limited knowledge of New Guinea mangrove distributions limits a thorough understanding of the evolutionary biogeography however.
The mapping by Danaher as part of the NR06 program (1994) used satellite interpretation to identify fifteen mangrove communities. Table 9.1 shows these communities and the seagrass mapping units also.
Table 9.1 Marine Vegetation Classes (Danaher 1994)
1 Rhizophora closed *
2 Rhizophora open
3 Ceriops closed
4 Ceriops open
5 Avicennia closed
6 Avicennia open
7 Rhizophora/Ceriops closed
8 Rhizophora/Ceriops open
9 Avicennia/Ceriops closed
10 Avicennia/Ceriops open
11 Landward Rim closed
12 Landward Rim open
13 Mixed closed
14 Mixed open
15 Saltpan open
16 Seagrass Density
< 10% of area
17 Seagrass Density
10-50% of
area
18 Seagrass Density
50-100% of
area
* Closed communities are those in which the foliage or canopy cover of the mangroves is greater than 70% of the total ground area.
Seagrass communities are also important for their ecological and commercial significance. They are particularly important as nursery areas for prawn and lobster fisheries and grazing areas for dugongs (Dugong dugon) and green turtles (Chelonia midas) (Poiner et al 1989). Sea grasses require shelter from high energy waves, light for photosynthesis and minimal exposure to air (Danaher 1994).
The Queensland Department of Primary Industries has mapped and sampled seagrasses along the Queensland coast (Coles et al 1992 and 1985 and Lee Long et al 1993). Danaher (1994) has incorporated their mapping into the CYPLUS NR06 report and GIS coverage. The mapping has a number of limitations, due to the seasonality (extent of seagrass varies with season), depth of survey (only shallow [<20 metre depth] seagrasses have been surveyed) and difficulties of accurate mapping and precise positioning in marine environments (Coles et al 1992).
There are 12 genera and 55 species of seagrass recognised around the world (Larkum & Den Hartog 1980). Mukai (1993) considers the global distribution of seagrasses and concludes the coastal waters of Malesia are the centre of origin for sea grasses and marine currents have been largely responsible for their distribution throughout the Indo-Pacific.
Australia has the highest number of seagrass species of any continent in the world with particular communities being amongst the most diverse in the world (Larkum & den Hartog 1989). With 14 species identified from the Torres Straits and east coast of Cape York (Lee Long et al 1993) this area is clearly a special case in terms of seagrass distribution. Lee Long et al (1993) have grouped the species information into mapping units for the east coast of Australia. Having twelve species, the areas of Barrow Point to Murdoch Point on Cape York Peninsula and Dunk Island to the South of Cairns are the most species rich along this generally rich east coast (Table 9.2). Flinders Island and Princess Charlotte Bay (9 species), Weymouth Bay, Cape Direction, Murdoch Point - Lookout Point and Bedford Bay - Cape Tribulation (8 species) and Escape River Margaret Bay, Bathurst Bay, Ninian River and Cape Flattery (7 species) are all areas notable as species rich areas.
Consideration of areas of particular note for Dugong has been undertaken in Section 17.4 of this report.
Danaher (1994) mapped fifteen mangrove communities as part of the CYPLUS NRAP Marine Vegetation Survey (NR06). Neldner and Clarkson - NR01 (1994) also mapped mangrove areas. A direct comparison of data sets was not feasible because different classes were mapped. The Danaher (1994) mapping included both seagrass and mangrove communities and for this reason was most appropriate to use for the analysis and plotting of the results.
The ecological significance of mangrove and seagrass communities makes all areas mapped important. It is however possible to determine those areas on the Peninsula that are of particular note. Danaher has broadly delineated areas of significance for fisheries reserves following a number of criteria (Danaher 1994). These criteria relate to some aspects of the RNE criteria outlined in Table 9.3. The application of the RNE criteria may include other attributes to those of the Fisheries Reserves Criteria or a combination thereof. For example, in determining representative areas (Criterion D), the AHC considers condition and integrity important components: Size (1) and Disturbance History (5) above can be combined to provide a good indication of representative areas.
Table 9.3 Fish Habitat Reserve Criteria - RNE Criteria
Fish Description RNE Description
Habitat Criterion
Criterion
1 Size D1 Principle Characteristics
of Class/
Representativeness
2 Diversity of specific A3 Richness or diversity
Habitat Features
3 Diversity of Pacific A3 Richness or diversity
marine fauna and flora
4 Existing of potential A2 Areas for maintaining
fishing grounds existing processes.
Breeding and feeding
grounds.
5 Level of existing and D1 Principle Characteristics
future disturbances of Class/
Representativeness
6 Unique features B1 Rare or Uncommon features
7 Protected species B1 Rare or Uncommon features
The areas identified as important fish habitat areas (Danaher 1994), are considered to be of natural heritage significance.
The existing Fish Habitat Reserves include:
Danaher recognises additional areas of importance as fish habitat in the areas of:
Additional areas identified on the basis of seagrass species richness (Section 9.2 above) are:
The locations of these areas have been included on the Marine Vegetation coverage (Figure 9.1) and more detailed descriptions for each location can be obtained from Danaher (1994).
In addition to the sites identified by Danaher, parts of Albatross Bay can be considered to have conservation significance in terms of the extent of seagrass beds present and the diversity of mangrove species (17 species are known to occur in the Nature reserve east of Weipa (Paul Warren, COLMALCO, 1995, pers. comm.).