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Status

Coral and macroalgal cover are typically expressed

in terms of their relative proportions (in relation to

On a regional scale, AGRRA surveys (1999-2001)

each other and other functional groups). Benthic

found an average of 14% live coral cover, with 15%

cover can be analyzed in various ways -- from a single

cover on fore reefs and 11% on reef crests19. These

coral cover measurement to multivariate analysis of

values are consistent with other regional and large-

multiple biotic classes4.

scale (Belize) assessments, but are lower than the

Usefulne s s

Usefulness

AGRRA Caribbean average (20% for all habitats, or

26% on forereefs)6,19,20,21. The average coral cover for

Coral cover is one of the most commonly measured

MBRS synoptic monitoring sites (Belize and Mexico,

parameters in reef monitoring programs. It is used

all habitats, 2004/05) was 23%21.

to assess the status of the reef-building corals and is

the end result of all reef processes (e.g., competition,

Significant loss of coral cover occurred after the

herbivory, mortality, reproduction).

decline of acroporids (staghorn and elkhorn corals)

and the die-off of Diadema sea urchins in the 1980s22.

The Mesoamerican Barrier Reef System (MBRS)

Bleaching events in 1995 and 1998, along with several

Project's Synoptic Monitoring Program and the AGRRA

hurricanes (notably Hurricane Mitch in 1998), caused

program use an accepted line transect method to

additional punctuated declines in coral cover6.

measure coral and macroalgal cover16,17. The transect

method requires training in species identification but is

Macroalgal abundance (from the same AGRRA dataset)

cost-effective and relatively easy to use. Video-based

in the MAR region averages 25%, with higher amounts

monitoring offers the advantage of producing archive

on fore reefs (27%) than reef crests (19%)16. The MAR

imagery and enabling more transects and data points

value is lower than the Caribbean value (34% for all

to be collected in a single dive, but these benefits are

habitats). However, the MBRS Synoptic Monitoring

offset by the cost of the video equipment (US$2500),

Program (SMP) found 35% macroalgal cover (Belize

possibility of equipment failure, decreased taxonomic

and Mexico, all habitats, for 2004/05)17.

resolution (especially of algae) and  added time

Data Needs

Data

required for image analysis. Relatively large sample

areas are usually required.

Several datasets are available from site-level surveys

within the MAR, but are difficult to compare due to

Including crustose coralline cover and other function-

different methodologies, habitat types, and depths.

al benthic components strengthens, but also compli-

Semi-historical baseline data are available (ca. 1980s)

cates, the analysis. Full-community multivariate anal-

for the MAR and Caribbean.

ysis is complex and moderately difficult to interpret

-- especially without comparable historical data -- but

A large-scale AGRRA survey was conducted across

has more power to distinguish among various influ-

the MAR in summer 2006 and will complement other

ences than do single measures of coral cover.

routine monitoring programs, most of which are

focused on marine protected areas (MPAs).

Coral cover is naturally highly variable from reef to reef,

due to factors such as latitudinal location, depth and

We recommend that a concerted effort be made to

wave energy. Thus, directly diagnosing the causes of

synthesize existing and historical data, to reconstruct

coral cover decline is often difficult. Comparing across

historical baselines and trends, particularly prior to

similar habitats is important in distinguishing natural

1960. Special effort should be devoted to tracking

from human stressors.

down hard-to-get data, such as that found in masters'

theses, and to conducting a large-scale, historical

Although changes, particularly in macroalgal cover,

meta-analysis.

can be rapid, coral cover is not an "early warning sign"

of adverse changes in reef health, since the coral

Future revisions of this indicator profile may include

death has already occurred, often in a gradual, even

crustose coralline algae coverage as a third parameter

insidious, manner.

in the ratio, given the importance of this taxon as a

facilitator of coral recruitment.

Coral cover can be an effective management and

communications tool as it is easy to understand.

However, it is often difficult to see an immediate

response in coral cover related to management

actions because most Caribbean corals grow very

slowly. Changes in coral and macroalgal cover are also

influenced by numerous abiotic factors and processes

S4

not directly under the control of local managers.

S5

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