Abstract:
An examination was made of the genetic variation with age in mangrove populations in two estuaries in south-east Australia, one
contaminated, the other uncontaminated. Sediment nutrient and metal levels, and isozyme/allozyme complements were measured in
three age-classes in four stands in each estuary, to identify site and intergenerational genetic composition, and influences of sediment
contamination. Within each river, there were greater genetic distances among the age-classes than among sampling sites. A
downstream gradient of genetic distance was found in the uncontaminated river, but not the contaminated one, where genetic
distances seemed to reflect site-specific factors, though apparently not the present sediment metal or nutrient levels. It appears that
genetic distances in the polluted river may reflect past fluctuations in pollution pressures. In both rivers, genetic distances indicate
that the mangroves within one estuary form one population, with 'neighbourhood' differentiation.
