Reef Health Index
Capucin
Dominica
2005
e
is
RHI
2.8
s h r ou s
Subregion
30
Ma Fle
cro
ver
Co
m
Co m F
Calibishie
The Reef Health Index (RHI) score from 2005 was
considered ‘fair’ (RHI=2.8 out of 5). Coral cover
was high (score=4) and fleshy macroalgae was low
(score=4); suggesting these reefs could support
larger fish populations. Scores for the biomass
of fish were poor because of the low abundance
of large parrotfish and large predatory fish. The
score for 2015 is projected to be lower due to
the potential loss of coral from subsequent coral
bleaching events and continued local impacts.
H Hodges
Wesley
Portsmith
Pointe Ronde
Marigot
Dublanc
Morne Diabiotins
Anse Soldat
Plat Coubari H
Thibaud
Key findings :
1
• Dominica has many coral reef types, each
providing important habitat
H
H
Grande Savanne
Salisbury
• At least 10-15% of live coral cover has
been lost on many reefs since 2005 1
H
H
• Abundant Diadema urchins have reduced
macroalgae
• Lack of large-sized female fish means fewer
eggs to replenish populations
Mero
H
Castle
Bruce
St. Joseph
Rosalie
Subregion
29
• Marine managed areas may be helping
some fish to recover in those areas
Mahaut
• Reefs considered in better condition ( H ) in
2013 included Grande Savanne, Salisbury,
Mero S, Mero W, Batali, Cachacrou, Plat
Coubari and Hodges Reefs 1
La Plaine
Roseau
Dominica’s Reef Health Index (RHI)
Indicator
Year Score
Average Trend Caribbean**
Coral Cover 2005 Good 25 n/a 14
Fleshy Macroalgae 2005 Good 4 n/a 30
Herbivorous Fish 2005 Poor 1200 n/a 3928
Commercial Fish 2005 Critical 395 n/a 2823
Reef Health Index Scores
The Reef Health Index “scores” are
calculated by converting the average data
value of each indicator into a condition
ranking from ‘critical’ to ‘very good’ based
on reference values (right). The four scores
are averaged to obtain the overall RHI
score. The pie displays the overall RHI
(middle) and each individual indicator to
show how each indicator affects the score.
Berekua
Soufriere
Scott’s Head
H
Reef Health Index Reference Values*
Critical
1-1.8 Poor
1.9-2.6 Fair
2.7-3.4 Good
3.5-4.2 Very Good
4.3-5
<5 5.0-9.9 10.0-19.9 20.0-39.9 ≥40
Fleshy Macroalgal Cover (%) >25.0 12.1-25 5.1-12.0 1.0-5.0 0-0.9
Herbivorous Fish (g/100m 2 ) <960 960-1919 1920-2879 2880-3479 ≥3480
Commercial Fish (g/100m 2 ) <420 420-839 840-1259 1260-1679 ≥1680
The Reef Health Index (RHI)
Coral Cover (%)
Steiner SCC (2015) Coral Reefs of Dominica (Lesser Antilles). Ann. Naturhist. Mus. Wien, B, 177:47-119. ITME Research Reports 33 and Institute Tropical Marine Ecology
( www.itme.org ). *Reef Health Index developed by Healthy Reefs Initiative ( www.healthyreefs.org ). **Caribbean average based on AGRRA regional database 2011-2014 (www.agrra.org ).
A trend is calculated after an indicator has been assessed for at least two years, otherwise it is listed as not available (n/a). For data, maps, and references see www.caribnode.org .
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