scholarly journals Connectivity of the seagrass Zostera muelleri within south-eastern Australia

2019 ◽  
Vol 70 (8) ◽  
pp. 1056
Author(s):  
R. E. Stafford-Bell ◽  
W. F. D. van Dongen ◽  
R. W. Robinson ◽  
A. A. Chariton
Keyword(s):  
Ecosystem Engineer ◽  
Genetic Material ◽  
Clonal Diversity ◽  
Genotypic Diversity ◽  
Genetic Connectivity ◽  
Genetic Population ◽  
South Eastern ◽  
Eastern Australia ◽  
Vegetative Propagules ◽  
South Eastern Australia

Contemporary oceanic conditions and local dispersal of propagules influence the genetic diversity and connectivity among seagrass populations. The degree of connectivity between populations of Zostera muelleri in south-eastern Australia is unknown. In this study we examined genetic connectivity among 25 sites containing Z. muelleri using nine polymorphic microsatellite DNA loci. We hypothesised minimal sharing of genetic material between distant populations and a degree of connectivity between local populations. Genotypic diversity was high, with 64% of populations having unique multilocus genotypes (MLGs), indicating the importance of sexual reproduction. Two sites shared MLGs, which may be due to the dispersal and recruitment of vegetative propagules. Genetic differentiation was observed between most sites. With the exception of two outlying sites, two genetic population clusters were identified across the studied populations. Regionally, the populations have high clonal diversity, are strongly differentiated and generally exist in isolation from one another. However, non-significant within-estuary differentiation was observed for three estuaries, indicating a degree of connectivity. The results of this research improve our understanding of the connectivity of Z. muelleri populations in the region, an important process for managing this ecosystem engineer.

Interactions between the superb lyrebird (Menura novaehollandiae) and fire in south-eastern Australia

2014 ◽  
Vol 41 (3) ◽  
pp. 203 ◽  
Author(s):  
Daniel T. Nugent ◽  
Steven W. J. Leonard ◽  
Michael F. Clarke
Keyword(s):  
Ecosystem Engineer ◽  
Alternative Stable States ◽  
Landscape Scale ◽  
Food Sources ◽  
Fire Behaviour ◽  
South Eastern ◽  
Fuel Loads ◽  
Eastern Australia ◽  
Forest Fuel ◽  
South Eastern Australia

Context The superb lyrebird Menura novaehollandiae is thought to be an important ecosystem engineer that, through its foraging, accelerates the decomposition of litter in Eucalyptus forests. Lyrebird foraging is therefore likely to affect forest fuel loads and hence fire behaviour in these fire-prone forests. In turn, fire is likely to reduce the abundance and influence the distribution of lyrebirds. Aims Our goal was to determine the impacts of a major bushfire on the habitat and food sources for the superb lyrebird and the effects of foraging activities of lyrebirds on litter fuel and potential fire behaviour in gullies of herb-rich foothill forests. Methods The effect of fire on lyrebirds and their habitat in the post-fire environment was examined at the landscape-scale, 2 years after fire; and at the patch-scale, 3 years after fire. Paired exclusion and control plots were also used over a 9-month period to assess the effects of foraging by the lyrebird on litter accumulation and fuel connectivity. Fire-behaviour models were used to determine the potential influence of lyrebird scratchings on fire behaviour. Key results At the landscape scale, lyrebirds were present in both unburnt and ground-burnt sites, but not in canopy-burnt sites. Within patchily burnt sites, lyrebirds favoured foraging in unburnt patches. On average, lyrebird foraging reduced litter fuel loads by 25% (1.66 t ha–1) in plots in which they were free to forage, compared with plots from which they were excluded, over a 9-month period. Fire-behaviour modelling showed that lyrebird foraging led to a lower likelihood of fire occurring and less intense fire. Conclusions Distinctly different vegetation structure and composition between burnt and unburnt patches appears to influence both the foraging patterns and distribution of lyrebirds. Additionally, foraging by lyrebirds reduces surface fuel loads and fuel connectivity such that fire spread is likely to be inhibited. Implications We propose that alternative stable states may emerge in Eucalyptus forests as a result of feedback mechanisms among lyrebirds, vegetation and fuel accumulation. Therefore, the ecological role of lyrebirds is an important consideration in forest fuel management and conservation in these extensive, fire-prone forests in south-eastern Australia.

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