[Coral-List] Shannon Weaver
judith_mendes at hotmail.com
Fri Jan 2 09:23:44 EST 2004
One difficulty with the meta-analysis you are planning is the wide variety
of methods used to collect coral abundance data. With respect to their
effect on the calculation of diversity the methods can be divided into two
1. Those that estimate abundance from the projected planar area, the two
dimensions x and z (e.g. methods with images taken from a camera/video
camera mounted above the coral).
2. Those that estimate abundance from surface relief, the two dimensions x
and y (e.g.
Methods in which a line or chain is draped over the coral). This means that
the resulting abundance estimates are affected by the morphology of the
coral species. Species with high relief e.g. Acropora will appear more
abundant when a method that measures abundance in the xy plane is used when
compared with their abundance estimated in the xz plane.
While this difference in the way abundance is estimated different methods
may sound trivial, it can lead to very different estimates of diversity for
the same location, particularly if the diversity index chosen emphasises the
relative abundance of species in its calculation. The best book explaining
the variety of diversity indices and the aspect of community composition
that they emphasise (species richness or evenness/dominance) is still
Ecological Diversity and its Measurement by Anne Magurran (1988). It even
contains a nice Caribbean coral reef example from Barbados showing diversity
increasing with depth and distance from Bridgetown, the capital, on the west
coast of the island. This example is taken from Tomascik, T. and Sander, F
(1987) Effects of eutrophication on reef building corals II
94:53-75. I see Anne Magurran is bringing out a new book this month
entitled Measuring Biological Diversity; perhaps this will be even better
than the original.
Some methods, such as the CARICOMP method, include an index of surface
relief /rugosity which can be useful in addressing this issue.
I have data from 1 site on the south coast of Jamaica which you are welcome
to have. Good luck with your meta-analysis.
>From: "Mark Vermeij" <Mark.Vermeij at noaa.gov>
>To: coral-list at coral.aoml.noaa.gov
>Subject: [Coral-List] Shannon Weaver
>Date: Mon, 22 Dec 2003 14:35:31 -0500
>For a comparitive study I would be interested in diversity indices on coral
>communities throughout the Caribbean bassin. I was thinking of Shannon
>Weaver indices as they correct for "abundance", but surprisingly little can
>be found regarding this measure related to Caribbean corals. E.g. a search
>with google results in information on line-dancing (amongst other
>interesting topics), but no relevant information in relation to corals was
>found. If you have such data, or know a place were to find this, I would
>greatly appreciate your suggestions. Basically what I'm looking for is a
>detailed quantification of coral abundance (either through number or
>cover), that includes the majority of corals known to be present at that
>location. Based on this information the calculation of the SW-index for
>this location should be simple.
>Thanks for your help and with best regards,
>Dr. Mark Vermeij
>Cooperative Institute for Marine and Atmospheric Studies (RSMAS/UM)
>NOAA Fisheries, Southeast Science Center
>75 Virginia Beach Dr, Miami, FL 33149 USA
>Tel: +1 305-361-4230, Fax: +1 305-361-4499 E-mail: Mark.Vermeij at noaa.gov
>Coral-List mailing list
>Coral-List at coral.aoml.noaa.gov
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