PARENT SESSION
Oral Session 76: Biodiversity V: Marine.
Presiding: AA Sabor
Wednesday, August 4, 1:30 PM to 5:00 PM, Meeting Room B 110.
Seagrass decay: Little evidence of seagrass species richness influencing mass loss rates.
Moore, Tim*,1, Fairweather, Peter, 1 School of Biological Sciences, Flinders University, Adelaide, South Australia, Australia
ABSTRACT- It is well established that the number of species in a given area can play a significant role in controlling or impacting rates of ecosystem functions such as productivity. Terrestrial studies have typically shown that increasing species number has a positive effect on primary productivity. The number of species in an ecosystem contributing detrital matter has been hypothesized to influence litter decay rates in much the same way. However, terrestrial biodiversity / decay studies have shown the positive relationship to be more tenuous, or even not apparent. Given the importance of nutrient cycling and decay cycles in impacting productivity, and the deficit of such studies in marine systems, we designed an experiment to test how a triumvirate of dominant seagrass species impacted decay rates. The study was performed in southern Australia, where at least 12 species of seagrass are present, inhabiting vast areas of soft sediment. In a fully replicated time series, we determined the in situ decay rate of all three species on their own, as well as in orthogonal two- and three-species combinations. We determined that initial short term (2 week) mass loss of biomass was well predicted in mixed species bags by the rate of decay of the constituent species in a simple additive fashion. However, after an extended period, such a pattern deteriorated, potentially indicating factors other than species richness are of greater importance to decay rates in marine systems.
Key words: decay, southern australia, biodiversity, seagrass