Downstream effects of land use on shallow-water benthic microalgal communities in Moreton Bay, Australia and Marovo Lagoon, Solomon Islands

Grinham, Alistair Robert (2007). Downstream effects of land use on shallow-water benthic microalgal communities in Moreton Bay, Australia and Marovo Lagoon, Solomon Islands PhD Thesis, School of Engineering, University of Queensland.

       
Attached Files (Some files may be inaccessible until you login with your UQ eSpace credentials)
Name Description MIMEType Size Downloads
n01front_grinham.pdf n01front_grinham.pdf application/pdf 3.24MB 22
n02content_grinham.pdf n02content_grinham.pdf application/pdf 3.24MB 32
Author Grinham, Alistair Robert
Thesis Title Downstream effects of land use on shallow-water benthic microalgal communities in Moreton Bay, Australia and Marovo Lagoon, Solomon Islands
School, Centre or Institute School of Engineering
Institution University of Queensland
Publication date 2007
Thesis type PhD Thesis
Supervisor Dr James Udy
Abstract/Summary Coastal marine zones occupy the interface between terrestrial and deep ocean systems and are of fundamental importance to life on earth. These have undergone dramatic changes in many parts of the world with large scale declines in water quality, primarily due to development of coastal catchments, which results in increased terrestrial sediment and nutrient loading to nearshore waters. This generally increases pelagic primary productivity, increases turbidity and reduces benthic light availability. The benthic autotrophic community of these areas may undergo radical changes with the complete loss of macrophytic communities increasingly reported. The effects on the benthic microalgal community are less studied, primarily because changes in these communities are more difficult to observe due to their microscopic nature. However, they are a key component of shallow-water ecosystems, buffering the effects of nutrient enrichment and contributing up to 50% of primary productivity in coastal systems. The aim of this thesis was to determine the impact of catchment development on benthic microalgal productivity in two shallow-water lagoonal systems. The first system was Moreton Bay, located off the east coast of Queensland, Australia, where catchment areas are highly developed and changes in landuse have occurred over the past century. The second was Marovo Lagoon in the Western Province of the Solomon Islands which, although relatively undeveloped, has recently undergone major changes to land use in catchment areas. Subtidal benthic microalgal gross primary productivity (GPP) was strongly limited by light availability. In both systems catchment development was shown to have decreased benthic light availability in the degraded areas and this has caused significant declines in benthic microalgal GPP in these areas. In Moreton Bay winter increases in benthic light availability did not result in increased productivity as benthic microalgal GPP was shown to be strongly limited by water temperature during this time. The declines in subtidal GPP of degraded areas caused the annual contribution of benthic microalgae to primary productivity in the bay to be almost 3 times lower than previously thought and over a third lower than during pre-European settlement. In Marovo Lagoon subtidal GPP in degraded areas was 10 times lower than in unaffected areas. These findings suggest that catchment development has negatively affected benthic microalgal productivity in both systems and confirms the global trend in declining coastal zones. These fundamental changes in primary productivity of the coastal zone may reduce their role in buffering the effects of terrestrial sediment and nutrient input leading to the formation of coastal “dead zones.”

 
Citation counts: Google Scholar Search Google Scholar
Created: Fri, 21 Nov 2008, 15:59:47 EST