'%Healthy Reefs for Healthy People - A Guide to Indicators of Reef Health and Social Well-being in the Mesoamerican Reef Region%'%by Melanie McField and PAtricia Kramer%

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field sampling effort, cost, etc.)5.

Melanie McField / WWF

The relationship between a given biodiversity index

value and reef health is not a simple one. There is no

simple relationship between the numbers of species

found on a degraded site versus a healthy site.

Richness or diversity values naturally vary depending

upon reef type, past disturbance and survey method.

Species evenness might not be sensitive to species

replacement. (In other words, species replacement

could be occurring on the reef, but an evenness

measure alone may not pick up that change.)

Datasets will be difficult to compare if there are (1)

differences in the taxonomic categories used in

different studies (e.g., one study may classify according

to genus, while another may classify according to

species or even sub-species), and (2) great variation

in total sampling effort (sample area / sample size).

Moderate training in species identification, taxonomic

standardization and field sampling is required.

St atus

Status

There are at least 67 species of corals in the

Mesoamerican Reef region.

Coral diversity at many MAR locations has declined over

the past 20 years due to high coral mortality. In some

cases, once-dominant reef-building corals have been

replaced by other species, such as Porites asteroides,

which do not contribute as much to reef construction,

given their smaller size and morphology.

One representative study conducted in 1997 on 12

fore reef sites throughout Belize measured a Shannon-

Wiener diversity index of 1.8; species richness

averaged more than 30 species per site (for a 225 m2

sample area). These data were collected after several

major reef events (Diadema die-off, acroporids losses,

1995 bleaching), but before the devastating 1998

bleaching and Hurricane Mitch events. In 1999, these

same 12 sites had a diversity index of 1.46.

Data

Data Needs

Comparable datasets are available for a limited

number of sites in the MAR region.

Additional large datasets suitable for direct

comparison are needed from across the region at

multiple reef-habitat types. More informed targets

can then be established.