Hh. Deiongh et al., SEAGRASS DISTRIBUTION AND SEASONAL BIOMASS CHANGES IN RELATION TO DUGONG GRAZING IN THE MOLUCCAS, EAST INDONESIA, Aquatic botany, 50(1), 1995, pp. 1-19
Seagrass distribution and seasonal changes in biomass and total organi
c C were studied in relation to dugong grazing, in intertidal meadows
dominated by Halodule uninervis (Forssk ($) over circle al) Ascherson
between December 1990 and December 1992 in Nang Bay on the east coast
of Ambon. Both below-ground and above-ground biomass of Halodule unine
rvis significantly increased during the transition period from the dry
season to the wet season between February and May. Above-ground bioma
ss of Halodule uninervis decreased significantly during the wet season
(between May and August), when low tide occurred in day time, and onl
y slow recovery took place until November. Below-ground biomass remain
ed high until November, resulting in a significant decrease of the rat
io of above-ground to below-ground biomass during the period between M
ay and August, and in a 'sparse' visible seagrass meadow, with a non-v
isible high below-ground biomass between August and November. Total or
ganic carbon level in the below-ground plant parts gradually increased
between May and August with a peak value in August. Dugong grazing re
moved 93% of the shoots and 75% of the below-ground biomass of the upp
er 4 cm deep layer of sediment. Seagrass biomass in freshly,orated fee
ding tracks was restored to levels of the nearby seagrass bed after 5
months during the onset of the wet season. No significant restoration
took place during the dry season. The frequency of dugong grazing show
ed a strong positive correlation with total organic C level in the bel
ow-ground plant parts,indicating that the dugongs preference for the H
alodule uninervis seems to be based on a strategy of a high net rate o
f energy intake.