Seedling development and patch formation of the seagrass Posidonia australis in a southeast Australian estuary
In: Aquatic Botany. Elsevier Science: Tokyo; Oxford; New York; London; Amsterdam. ISSN 0304-3770; e-ISSN 1879-1522, more
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| Keywords |
Anatomical structures > Body organs > Plant organs > Plant reproductive structures
Anatomical structures > Body organs > Plant organs > Rhizomes
Anatomical structures > Body organs > Plant organs > Shoots
Flora > Weeds > Marine organisms > Seaweeds > Sea grass
Patchiness
Reproduction > Vegetative reproduction
Seedlings
Water bodies > Coastal waters > Coastal landforms > Coastal inlets > Estuaries
Posidonia australis J.D.Hooker, 1858 [WoRMS]
PSE, Australia, New South Wales, Georges Estuary [Marine Regions]
Marine/Coastal |
| Author keywords |
seagrass; Posidonia australis; seedling; patch formation; estuary |
| Abstract |
Seedlings of the seagrass Posidonia australis are rarely found and little is known about their development. St. Georges Basin, an estuary in southeast Australia, harbours relatively large numbers of P. australis seedlings and patches. Seedlings of varying age were collected from four sites within the estuary. Mature plagiotropic shoots (horizontal rhizomes) on existing beds were tagged to measure vegetative growth and provide a plastochrone interval with which to age the seedlings. The abundance of P. australis seedlings ranged from 0.001 to 0.014 seedlings m-2. Based on the plastochrone intervals (plagiotropic: 33±0.8 days; orthotropic: 48.0±1.4 days) estimated seedling age ranged from 0.7 to 8.2 years. Both the numbers of shoots and leaf areas were related to seedling age, with increases particularly evident between 2 and 5 years. Of 57 seedlings either collected or observed in situ, only 6 had produced a plagiotropic shoot. Rhizome growth for the seedlings ranged from 5.1±0.5 to 17.1±1.3 cm per year, which was slower than the mean rhizome growth of mature plants (21.4±1.0 cm per year). A development time-line was constructed for P. australis for the first 5 years of seedling growth based on the data collected. On average, production of a second shoot occurred at the age of 2.7±0.3 years, and thereafter approximately one shoot was produced per year. Plagiotropic shoots (horizontal rhizomes) did not begin to develop until 4.3±0.7 years. |
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