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CRAMP Rapid Assessment. Sediment Analysis
The gravel fraction is removed prior to analyses to reduce overweighting proportions of other size fractions by large material. To avoid multicollinearity, one size fraction (very fine sand) was removed from the analysis. Additionally, partial F-tests determined that this grain-size to contribute the least in explaining sediment variability among sites.
Bulk sediments were collected from 94 of the 152 stations at 52 sites. At stations where sediments were not collected, sediment data from stations at the same site with similar biota and environmental conditions were substituted (>90%) using a similarity matrix. Stations not meeting substitution criteria were omitted from the analyses (15).
Five sediment parameters were used in analyses:
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Loss on ignition (LOI500) was used as an index of organic material content
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The mass loss between LOI500 and LOI1000 was used as a proxy for the carbonate fraction (CaCO3)
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Medium sand fraction
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Fine sand fraction
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Silt/clay fraction
Principal components analysis (PCA) is used to define the position of stations in relation to the sediment variables.
Last Update: 04/21/2008
By: Lea Hollingsworth
Hawai‘i Coral Reef Assessment & Monitoring Program
Hawai‘i Institute of Marine Biology
P.O. Box 1346
Kāne‘ohe, HI 96744
808-236-7440 phone
808-236-7443 fax
email: jokiel@hawaii.edu