Porites growth characteristics in a changed environment: Misima Island, Papua New Guinea |
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Authors: | D J Barnes J M Lough |
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Institution: | (1) Australian Institute of Marine Science, PMB 3, Townsville M.C., Queensland 4810 Australia e-mail: d.barnes@aims.gov.au, AU |
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Abstract: | The construction in 1988 of an open-cut gold mine and ore-processing facility at Misima Island, Papua New Guinea, resulted
in disturbance of the adjacent fringing coral reef, mostly because of large increases in sedimentation. This provided an opportunity
to examine whether growth characteristics of the major reef-building coral, Porites, changed in response to this sudden and sustained increase in sedimentation. Annual variation in skeletal density was measured
in 93 colonies variously affected by sedimentation. The colonies provided data for average annual density, annual extension
and annual calcification covering the periods 5 y before and 5 y after mining operations began. The average depth of skeleton
occupied by tissue (tissue layer thickness) was also measured for most colonies. There was high mortality of Porites in regions strongly affected by increased sedimentation. In colonies that survived, density, extension and calcification
tended to be less (in some cases significantly) in the period after mining operations began compared with pre-construction
levels. However, these decreases were not linked with proximity to the mine site and probably reflect a regional-scale response
of Porites growth to some other environmental change. This suggests that periods of high sedimentation may not be recorded by the growth
characteristics of massive Porites. Average growth characteristics of surviving Porites from Misima Island were similar to those from inshore reefs of the northern Great Barrier Reef (GBR). Tissue layer thickness
in Porites from the control areas at Misima Island were also similar to colonies from the northern inshore GBR reefs. However, tissue
layer thickness significantly decreased with increased proximity to the mine site at Misima Island.
Accepted: 15 May 1999 |
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Keywords: | Sedimentation Porites Skeletal density banding Growth characteristics Tissue thickness |
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