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Publication year : 0
Thematic : Coral Reef
Language : English
Note
Coral reef communities of the western Atlantic
have changed over the past two to three decades, but
the magnitude and causes of this change remain
controversial. Part of the problem is that small-scale
patterns observed on individual reefs have been erroneously
extrapolated to landscape and geographic
scales. Understanding how reef coral assemblages vary
through space is an essential prerequisite to devising
sampling strategies to track the dynamics of coral reefs
through time. In this paper we quantify variation in the
cover of hard corals in spur-and-groove habitats
(13}19 m depth) at spatial scales spanning "ve orders of
magnitude along the Florida Reef Tract. A videographic
sampling program was conducted to estimate
variances in coral cover at the following hierarchical
levels and corresponding spatial scales: (1) among transects
within sites (0.01- to 0.1-km scale), (2) among sites
within reefs (0.5- to 2-km scale), (3) among reefs within
sectors of the reef tract (10- to 20-km scale), and (4)
among sectors of the reef tract (50- to 100-km scale).
Coral cover displayed low variability among transects
within sites and among sites within reefs. This means
that transects from a site adequately represented the
variability of the spur-and-groove habitat of the reef as
a whole. Variability among reefs within sectors was
highly signi"cant, compared with marginally signi"-
cant variability among sectors. Estimates from an individual
reef, therefore, did not adequately characterize
nearby reefs, nor did those estimates su$ciently represent
variability at the scale of the sector.
T.J.T. Murdoch ( ) ' R.B. Aronson
Dauphin Island Sea Lab, 101 Bienville Boulevard, Dauphin
Island, Alabama 36528, USA; and Department of Marine Sciences,
University of South Alabama, Mobile, Alabama 36688,
USA
e-mail: tmurdoch@jaguar1.usouthal.edu
Fax:#1-334-861-7540
The structure and composition of coral reef communities
is probably determined by the interaction of
multiple forcing functions operating on a variety of
scales. Hierarchical analyses of coral assemblages from
other geographic locations have detected high variability
at scales di!erent from those in the present study.
A multiscale analysis should, therefore, precede any
management decisions regarding large reef systems
such as the Florida Reef Tract.
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Keywords : Hipposideros cineraceus
Encoded by : Pauline Carmel Joy Eje
