Journal of the Royal Society of Western Australia, 86(1), March 2003 
Mangrove margins at a number of locations had areas 
of previous mangrove mortality, although rates over the 
monitoring period 1997-1999 were 0-4% (Table 1). 
Adjacent to the vents, there are sections of shoreline 
where mangrove trees either appear to be unhealthy, 
with low leaf cover, or the trees are dead. At site 3 (Goat 
Bay), there is several hundred meters of largely dead 
mangroves. Occurrence of dead timber in Plot 3C is 
reflected by the low foliage cover (Table 2). This tree 
death occurred before December 1997, and may have 
been caused by storm damage. The broken canopy and 
relatively large size of trees in this plot may have 
weakened them to further storm damage. The recorded 
mortality of 6% in this plot was likely a result of Cyclone 
Vance in March 1999. 
There are several other possible causes of mangrove 
death at Lake MacLeod. These include salinity stress, as 
shown at the Embley River estuary in the Gulf of 
Carpentaria where death of Avicennia marina occurred 
following a series of drier than normal wet seasons, and 
consequent high soil salinities (Conacher et al. 1996). 
Change in lake water level could also cause mortality, 
either by increasing salinity stress with a drop in water 
level, or causing inundation stress with raised water 
level. Such effects would be documented by continued 
monitoring at these sites. 
In summary, the mangroves of Lake MacLeod are 
unique, being one of the world's larger inland mangrove 
areas. Despite their extreme habitat, on the margins of a 
non-tidal salt lake in an arid climate, these mangroves 
have high productivity. Rates of primary production, 
measured by litter fall and mangrove biomass per unit 
area, are equivalent to mangroves of similar height in 
normal coastal situations. 
The spatial extents of mangroves at Lake MacLeod are 
obviously controlled by water conditions, particularly 
water surface elevation that determines the inner margin 
of mangroves with the salt flat. Water salinity controls 
mangrove physiognomy, indicated by the stunted 
architecture of trees more distant from the water's edge. 
Pneumatophore heights in some areas indicate stress 
from periods of inundation during higher lake levels, 
and previous mortality events are apparent from before 
the period of this study. Having established this baseline 
study, future monitoring will elucidate these mortality 
events. 
Acknowledgements : This study was funded by Dampier Salt Limited, as 
part of their environmental management program. The authors thank 
Dampier Salt for granting permission to publish this work. Particular 
thanks go to Leon Staude, formerly of Dampier Salt, for initiating the 
study. Thanks also to Dave Bauer and Sarah Fraser for field assistance. 
References 
Beard J S 1967 An inland occurrence of mangroves. The Western 
Australian Naturalist 10:112-115. 
Clough B F, Dixon P & Dalhaus O 1997 Allometric relationships 
for estimating biomass in multi-stemmed mangrove trees. 
Australian Journal of Botany 45:1023-1031. 
Conacher C A, O'Brien C, Horrocks J L & Kenyon R K 1996 
Litter production and accumulation in stressed mangrove 
communities in the Embley River estuary, North-eastern Gulf 
of Carpentaria, Australia. Marine and Freshwater Research 
47:737-743. 
Daubenmire R F 1959 A canopy-coverage method of 
vegetational analysis. Northwest Science 33:43-66. 
Duke N C, Bunt J S & Williams W Y 1981 Mangrove litter fall in 
northeastern Australia. I. Annual totals by component of 
selected species. Australian Journal of Botany 29:547-553. 
Handford, C R, Kendall A C, Prezbindowski D R, Dunham J B, 
&: Logan B W 1984 Salina-margin tepees, pisoliths, and 
aragonite cements. Lake MacLeod, Western Australia. Their 
significance in interpreting ancient analogues. Geology 
12:523-527. 
Johnstone R E 1990 Mangroves and mangrove birds of WA. 
Records of the Western Australian Museum, Supplement 32, 
7-120. 
Lambeck K & Nakada M 1990 Late Pleistocene and Holocene 
sea-level change along the Australian coast. 
Palaeogeography, Palaeoclimatology, Palaeoecology (Global 
and Planetary Change) 89:143-176. 
Lane J, Jaensch R & Lynch R 1996 Western Australia. In: A 
Directory of Important Wetlands in Australia (eds R Blackley, 
S Usback & K Langford). Australian Nature Conservation 
Agency, Canberra, 759-870. 
Lugo A E 1981 The inland mangroves of Inagua. Journal of 
Natural History 15:845-852. 
Mackey A P & Smail G 1995 Spatial and temporal variation in 
litter fall of Avicennia marina (Forssk.) Vierh. in the Brisbane 
River, Queensland, Australia. Aquatic Botany 52:133-142. 
Saenger P & Snedaker S C 1993 Pan tropical trends in mangrove 
above-ground biomass and annual litter fall. Oecologia 
96:293-299. 
Semeniuk V & Wurm PAS 1987 The mangroves of the Dampier 
Archipelago, Western Australia. Journal of the Royal Society 
of Western Australia 69:29-87. 
Semeniuk V 1993 The mangrove systems of Western Australia: 
1993 Presidential Address. Journal of the Royal Society of 
Western Australia 76:99-122. 
Stoddart D R, Bryan G W & Gibbs P E 1973 Inland mangroves 
and water chemistry, Barbuda, West Indies. Journal of 
Natural History 7:33-46. 
Thomas M L H 1993 Mangrove swamps in Bermuda. Atoll 
Research Bulletin 386:1-17. 
Thomas M L H, Logan A, Eakins K E & Mathers S M 1992 Biotic 
characteristics of the anchialine ponds of Bermuda. Bulletin 
of Marine Science 50:133-157. 
Van Steenis C G G J 1963 Miscellaneous notes on New Guinea 
Plants VII. Nova Guinea Botany 12:189. 
Van Steenis C G G J 1984 Three more mangrove trees growing 
locally in nature in freshwater. Blumea 29:395-397. 
Woodroffe C D 1987 Pacific island mangroves: Distributions and 
environmental settings. Pacific Science 41:166-185. 
Woodroffe C D 1988 Relict mangrove stand on last Interglacial 
terrace, Christmas Island, Indian Ocean. Journal of Tropical 
Ecology 4:1-17. 
30 
