Development of a seagrass nursery for restoration of the intertidal seagrass, Zostera muelleri.

Seagrasses form meadows that provide a range of ecosystem services but these meadows are declining globally and there is growing interest in developing methods that will facilitate restoration. The development of nursery facilities that can provide material for restoration has not been explored in most species. The use of a nursery to germinate and rear seeds from the intertidal seagrass Zostera muelleri was evaluated through mesocosm studies. Nursery rearing experiments compared germination rates and growth of seeds planted in biodegradable pots (at four different burial depths) and hessian bags (seeds from different origins). Seed origin did not have a significant effect on survival and germination of seedlings. However, the germination success was <1%. Higher germination rates were observed for the biodegradable pots, especially for seeds buried at 1 and 2 cm deep, with germination rates of 27.50% and 23.33%. A subsample of successful seedlings in the biodegradable pots were subsequently planted into the field and compared to nursery seedlings. Field deployed seedlings showed a significantly higher survival with a 55% increase in number of leaves per pot compared to nursery-maintained seedlings with a decrease of 57% of leaves per pot. Variation in reproductive effort between three different donor meadows in three sites in Western Port Bay was assessed. The results of the seed bank analysis indicated that Corinella Bay and Woolleys Beach had a similar number of seeds (2.2 and 1.3 seed per core, respectively) in the seed bank compared to Coronet Bay which had significantly fewer seeds (0.2 seeds per core). These results are promising for seagrass restoration and providing material for restoration efforts. Furthermore, seedlings reared in the nursery appear to survive well once transplanted into the field and may significantly increase the success of future restoration programs.