ICES Journal of Marine Science (2011), 68(9), 1875–1883. doi:10.1093/icesjms/fsr129
Biogeographic patterns of reef fish community structure
in the northeastern Arabian Peninsula
John A. Burt 1*, David A. Feary 2,3, Andrew G. Bauman 2,4, Paolo Usseglio 2,5,
Georgenes H. Cavalcante 2,6, and Peter F. Sale 2
1
Department of Biology, New York University-Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates
United Nations University—Institute for Water, Environment and Health (INWEH), Hamilton, ON, Canada L8P 0A1
3
Department of Environmental Sciences, University of Technology, PO Box 123, Broadway, Sydney, NSW 2007, Australia
4
School of Marine and Tropical Biology, and ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia
5
Hawaii Cooperative Fishery Research Unit, Department of Zoology, University of Hawaii, 2538 The Mall, Honolulu, HI 96822, USA
6
Coastal Zone and Waterways Management Section, Environment Department, Dubai Municipality, PO Box 67, Dubai, United Arab Emirates
2
*Corresponding Author: tel: +971 50 2219269; fax: +971 2 659 0783; e-mail: [email protected]
Burt, J. A., Feary, D. A., Bauman, A. G., Usseglio, P., Cavalcante, G. H., and Sale, P. F. 2011. Biogeographic patterns of reef fish community
structure in the northeastern Arabian Peninsula. – ICES Journal of Marine Science, 68: 1875 – 1883.
Received 10 February 2011; accepted 5 July 2011.
This study provides the first large-scale comparison of reef-associated fish communities in the northeastern Arabian Peninsula, with 24
sites spanning .3000 km of coastline in the southern Persian Gulf, the western Gulf of Oman, and the northwestern Arabian Sea, each
with its own unique environmental conditions. Multivariate analyses revealed three distinct community types that were represented
mainly by sites within each major water body, with .70% dissimilarity in community structure between each. Persian Gulf communities had low species richness, abundance, and biomass of reef fish compared with the other subregions, with communities dominated by herbivores and generalist predators that had little association with live coral. Reef fish biomass in the Gulf of Oman and
Arabian Sea was comparable, and communities were dominated by fish with moderate coral association. However, there were relatively
more herbivores and larger fish in the Arabian Sea than in the Gulf of Oman, where communities were dominated by planktivores.
Species richness was highest in the Arabian Sea when differences in abundance among regions were accounted for. The influence of
distinct environmental and oceanographic conditions on reef fish community structure in each of these areas is discussed.
Keywords: Arabian Gulf, biogeography, Gulf of Oman, Persian Gulf, reef fish, zoogeography.
Introduction
The northeastern Arabian Peninsula is bounded by the Persian
Gulf, the Gulf of Oman, and the Arabian Sea, with each distinguished by different oceanographic conditions (Sheppard et al.,
1992; Coles, 2003). The Persian Gulf is a shallow, semi-enclosed
water body connected to the Gulf of Oman through the narrow
Strait of Hormuz. The marine environment of the Persian Gulf
is characterized by extreme environmental conditions, with salinity often .45, and highly fluctuating sea surface temperatures
(SSTs) ranging from 128C in winter to summer highs above
368C (Reynolds, 1993; Coles, 2003). The coastline of the Gulf of
Oman is bordered by a deep basin and has relatively mild seasonal
changes in SST (range 22– 318C) and salinity (ca. 37) along the
coast that are moderated by the input of seasonal upwelling
from the Arabian Sea (Reynolds, 1993; Böhm et al., 1999; Coles,
2003). The coast of the Arabian Sea, in contrast, is one of the
five largest upwelling areas of the world and is dominated by
extensive seasonal upwelling that increases coastal nutrient concentration in summer, leading to a tenfold increase in primary
productivity (Smith, 1995; Burkill, 1999; Schils and Wilson,
2006), with moderate salinity (36–37) and relatively cooler temperatures (range 20 – 268C) in the surface waters bordering the
# 2011
Arabian Peninsula (Elliott and Savidge, 1990; Morrison et al.,
1998).
Differences in environmental and oceanographic conditions
between the Persian Gulf, the Gulf of Oman, and the Arabian
Sea are likely to have substantial impacts on reef fish community
structure, but to date there have been no direct comparative
studies of fish assemblages among the regions. Several studies
have shown relatively distinct communities of corals and other
benthos in all three regions as a consequence of environmental
and oceanographic differences (Price, 1982; Sheppard and
Sheppard, 1991; Sheppard et al., 2000; Coles, 2003; Schils and
Wilson, 2006), and these differences likely apply to fish too.
Isolated studies of reef fish communities from each region indicate
that such differences are likely (Smith and Saleh, 1987; Smith et al.,
1987; Coles and Tarr, 1990; Krupp and Al-Marri, 1996; Carpenter
et al., 1997), but a comprehensive comparison of reef fish communities among the regions is lacking.
Our research examined the structure of reef fish communities
throughout the eastern Arabian Peninsula. The major objectives
of the study were to describe and compare the abundance,
species composition, richness, and trophic status of reef-associated
fish communities between the Persian Gulf, the Gulf of Oman, and
International Council for the Exploration of the Sea. Published by Oxford University Press. All rights reserved.
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1876
J. A. Burt et al.
Figure 1. Map of the study area, with numbers indicating the sampling sites: 1, Saadiyat; 2, RasGhanada; 3, SaihShaib; 4, RasHasyan; 5, Coral
Garden; 6, RashidIslandW; 7, EMusandam; 8, DibbaRock; 9, AlAqah; 10 –12, AlGhattan, AlJazeera, FortIsland; 13– 16, Qantab, JussaWest,
JussaIsland, JussaPoint; 17, AlHeddla; 18, Turtle Beach; 19 –21, Haliniyat1, Haliniyat2, AlSawdiIsland; 22– 24, Mirbat1, Mirbat2, Mirbat3. Site
coordinates are listed in Table 1.
the Arabian Sea. This represents the first large-scale comparison of
reef fish communities among the regions and provides important
baseline data on reef fish communities of the western Gulf of
Oman and northwestern Arabian Sea, areas that have been relatively poorly studied to date.
Methods
Reef fish communities were surveyed at a total of 24 sites spanning
.3000 km of coastline in three regions (Figure 1): the Persian Gulf
(sites 1 –4, see Figure 1 for site names), the Gulf of Oman (sites 5 –
18), and the Arabian Sea (sites 19 –24) in October and November
2008. Sites in the Musandam Peninsula (Figure 1, sites 5 and 6)
border both the Persian Gulf and Gulf of Oman, but were classified
as Gulf of Oman based on the similarity in environmental, oceanographic, and biological conditions between the regions (Reynolds,
1993; Pous et al., 2004; Thoppil and Hogan, 2010). At each site,
surveys were conducted on eight visual transects 30 × 5 m wide
at a depth of 5 –6 m. Although belt transects are recognized as
biasing against small and/or cryptic species, they represent the
most logistically feasible and widely used survey technique for
reef fish and are comparable in accuracy with ichthyocides (Sale
and Douglas, 1981). Along each transect, all fish (≥5 cm total
length, TL, to avoid small/cryptic fauna) observed were classified
to species level and placed in size categories. A single observer conducted all fish counts to preclude inter-observer bias.
Species were categorized into the following functional groups
based on their primary diet (Froese and Pauly, 2010): cleaners,
herbivores, invertivores, macroinvertivores, omnivores, planktivores, and generalist predators. In addition, using the published
literature (Randall, 1995), species were grouped into three categories of reef association: (i) those that settled or fed on the
coral reef (high coral reef association), (ii) those that only dwelt
within the coral reef structure (medium coral reef association),
and (iii) those that were not associated with the coral reef (low
coral reef association).
Total coral cover at each site was estimated using photoquadrats in the same transects used for fish censuses. On each transect,
11 replicate 0.25 m2 quadrats were photographed at intervals of
3 m, a total of 66 photoquadrats per site. A mean estimate of
coral cover at each site was calculated from 50 random points distributed across each image using CPCe image analysis software
(Kohler and Gill, 2006).
Mean fish abundance at each site was calculated from transects
and square-root transformed before analysis. Non-metric multidimensional scaling (NMDS) on Bray– Curtis distances was used to
ordinate fish communities at each site, and ellipses were overlaid
on the resulting ordination scatterplot to indicate the percentage
similarity of communities determined by hierarchical agglomerative cluster analysis based on group averages. Analysis of similarity
(ANOSIM) was used to test the significance of differences in fish
communities between the three major water bodies, and similarity
permutation analysis (SIMPER) was used to determine species
driving differences between these groups. Only species found on
more than 5% of transects were included in multivariate analyses
to preclude the confounding effects of outliers (McCune and
Grace, 2002). Differences in mean abundance (ha21), species richness (150 m21), biomass (kg ha21), and strength of coral association were compared using nested ANOVAs with sites nested
within the community groups identified in multivariate analyses.
Where there were significant differences, post hoc unequal-number
honestly significant difference (unequal-N HSD) tests were used to
identify different groups. As estimates of abundance and richness
1877
Biogeographic patterns of reef fish community structure in the NE Arabian Peninsula
Table 1. Location, coral cover, and fish species richness and diversity at each study site, with site numbers corresponding to those in
Figure 1.
Site number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Site name
Saadiyat
RasGhanada
SaihShaib
RasHasyan
Coral Garden
RashidIslandW
EMusandam
DibbaRock
AlAqah
AlGhattan
AlJazeera
FortIsland
Qantab
JussaWest
JussaIsland
JussaPoint
AlHeddla
Turtle Beach
Haliniyat1
Haliniyat2
AlSawdiIsland
Mirbat1
Mirbat2
Mirbat3
Coordinates
24835′ 54.90′′ N 54825′ 54.90′′ E
24850′ 51.36′′ N 54841′ 24.90′′ E
24855′ 15.30′′ N 54854′ 24.10′′ E
24858′ 17.93′′ N 54857′ 52.51′′ E
26822′ 34.60′′ N 56824′ 54.53′′ E
26824′ 19.02′′ N 56829′ 42.72′′ E
25846′ 28.23′′ N 56820′ 42.89′′ E
25836′ 12.51′′ N 56821′ 01.25′′ E
25829′ 34.62′′ N 56821′ 48.67′′ E
23847′ 40.93′′ N 57846′ 20.74′′ E
23847′ 29.46′′ N 57847′ 08.40′′ E
23847′ 16.14′′ N 57848′ 04.11′′ E
23833′ 52.20′′ N 58838′ 11.28′′ E
23833′ 31.27′′ N 58838′ 45.33′′ E
23833′ 33.51′′ N 58839′ 04.68′′ E
23833′ 25.80′′ N 58839′ 40.70′′ E
22845′ 25.32′′ N 59819′ 06.66′′ E
22831′ 57.48′′ N 59845′ 01.02′′ E
17833′ 02.46′′ N 56802′ 43.92′′ E
17828′ 41.88′′ N 55851′ 37.38′′ E
17828′ 20.41′′ N 55836′ 31.46′′ E
16856′ 46.38′′ N 54848′ 16.20′′ E
16856′ 44.40′′ N 54847′ 28.98′′ E
16857′ 14.22′′ N 54845′ 47.34′′ E
Coral cover (mean + s.e.)
34.3 + 5.2
26.3 + 3.9
11.8 + 2.0
28.7 + 2.2
69.0 + 5.5
27.9 + 6.4
32.5 + 3.2
52.5 + 12.5
7.4 + 0.7
24.9 + 5.6
6.6 + 3.5
6.1 + 1.7
9.7 + 2.0
9.4 + 2.1
7.1 + 2.6
4.8 + 1.4
7.6 + 1.4
6.2 + 1.0
7.0 + 2.3
37.7 + 3.6
20.2 + 2.8
36.0 + 5.8
5.0 + 1.9
23.9 + 5.8
Total fish richness (S)
24
22
18
14
29
36
44
45
30
39
37
46
34
41
29
35
43
44
43
45
38
59
34
48
Fish diversity (H’)
1.68
1.72
2.12
2.09
1.69
1.94
2.39
2.86
2.06
2.33
2.68
2.45
1.89
2.36
2.5
2.81
2.4
1.68
2.12
2.28
2.55
2.97
2.67
2.71
in a sample are often related, rarefaction techniques in EcoSim
(Gotelli and Entsminger, 2011) were used to rarefy and compare
fish species richness between subregions. Species richness was rarefied at 112 randomly selected individuals, a value representing the
smallest total number of individuals observed when comparing
between regions. The procedure was iterated 1000 times to find
the average expected species richness (+95% CI), controlling
for differences in abundance among regions. Linear regression
was used to test the association between fish abundance and
coral cover among sites.
Results
Sampling sites exhibited a range in coral cover, total fish richness,
and fish diversity (Table 1). Fish communities in the eastern
Arabian Peninsula fell into three distinct groups (NMDS ordination; Figure 2), and these groups were strongly and significantly
different from each other (ANOSIM, R ¼ 0.99, p , 0.001). Each
group was represented exclusively by sites from a distinct oceanographic region: the Persian Gulf, the Gulf of Oman, or the Arabian
Sea. These groups are labelled as Gulf-type, Oman-type, and
Arabian Sea-type groups hereafter. Cluster analysis indicated just
27.8% similarity between sites represented by Gulf-type communities and sites holding Oman- and Arabian Sea-type communities, but 46.6% similarity between communities in Oman- and
Arabian Sea-type sites (Figure 2).
The three fish community types identified by ordination were
highly dissimilar to each other (Table 2). Pairwise comparisons
of groups with SIMPER indicated that Gulf- and Arabian
Sea-type communities were most dissimilar, but that all combinations showed strong and significant differences (Table 2;
ANOSIM p , 0.01 each). The main species driving differences
between assemblages were generally more abundant in
Oman-type communities, except Lutjanus ehrenbergii, which was
Figure 2. Scatterplot of fish communities at each site from NMDS
ordination, with the percentage similarity of communities
encompassed by ellipses indicated.
more abundant in the Gulf-type community, and Pomacentrus
aquilus, which was more abundant in the Arabian Sea-type community (Table 2). Lutjanus ehrenbergii and Parapenaeus margaritatus were more abundant in the Gulf-type community than in the
Arabian Sea-type community, but the other species driving differences between these two groups were absent from Gulf-type sites.
1878
J. A. Burt et al.
Table 2. Percentage dissimilarity (d) of fish community types identified by ordination, with the contribution of the five most important
species driving differences listed (each of the other species contributed ,4.5% to dissimilarity).
Groups compared
Gulf and Oman type
Mean d
(%)
78.7
Gulf and Arabian Sea
type
84.9
Oman and Arabian Sea
type
72.1
Species
Chromis xanthopterygia
Pomacentrus leptus
Abudefduf vaigensis
Lutjanus ehrenbergii
Thalassoma lunare
Thalassoma lunare
Lutjanus ehrenbergii
Odonus niger
Chromis xanthopterygia
Parupeneus margaritatus
Chromis xanthopterygia
Pomacentrus leptus
Thalassoma lunare
Caesio varilineata
Pomacentrus aquilus
Group 1
abundance
(150 m2)
0.0
0.3
0.1
39.3
0.0
0.0
39.3
0.0
0.0
10.8
89.1
69.1
44.1
20.4
0.1
Group 2
abundance
(150 m2)
89.1
69.1
37.3
12.2
44.1
21.7
0.0
18.2
19.0
0.3
19.0
6.3
21.7
6.3
14.7
Contribution
of d (%)
10.1
8.4
5.6
4.9
4.8
5.7
5.1
4.5
4.4
3.7
6.7
6.4
4.7
4.2
3.8
Cumulative
d (%)
10.1
18.5
24.1
29.0
33.8
5.7
10.8
15.3
19.7
23.4
6.7
13.1
17.8
22.0
25.8
Figure 3. Mean species richness (+s.e.; 150 m22) at sites within each community type.
A full list of species observed in each region, and their density, is
given in the Supplementary material.
In all, 138 species of reef fish were observed. Nested ANOVA
revealed significant differences in species richness among fish
community types [F(4, 334) ¼ 21.8, p , 0.001] and among sites
within communities [F(42, 334) ¼ 4.4, p , 0.001; Figure 3].
Post hoc Unequal-N HSD tests revealed similar mean richness in
Oman- and Arabian Sea-type communities (16.6 + 5.2 and
14.7 + 0.7, respectively; p . 0.05) and that these communities
each had significantly higher richness than Gulf-type assemblages
(9.4 + 0.5; p , 0.001 each). However, using rarefaction to control
for differences in abundance between regions (see below), all three
regions were found to have significantly different richness from
each other, with the lowest in Gulf-type assemblages (12.6 + 0.4
95% CI), followed by Oman-type communities (18.1 + 2.9 95%
CI), and the highest in Arabian Sea-type communities (24.0 +
1.9 95% CI).
Mean abundance of fish varied significantly among community
types and sites within communities [Figure 4; nested ANOVA
F(4, 334) ¼ 28.8 and F(42, 334) ¼ 12.4, respectively, p , 0.001
each], with greater abundance in Oman-type communities
(373.3 + 30.5) than in Gulf- or Arabian Sea-type communities
Biogeographic patterns of reef fish community structure in the NE Arabian Peninsula
1879
Figure 4. Mean fish abundance (+s.e.; ha21) at sites within each community type.
(133.9 + 27.5 and 168.9 + 17.5, respectively; p , 0.001 each),
which did not differ significantly (p . 0.05). Much of this difference was accounted for by the three sites in the Musandam
Peninsula, which had, on average, more than three times as
many fish as other sites, mainly because of the abundance there
of Chromis xanthopterygia (Pomacentridae) and Thalassoma
lunare (Labridae), which together constituted 51% of all fish at
those sites. However, even with those sites excluded as outliers,
the patterns of significant differences were identical among communities [F(2, 147) ¼ 16.5, p , 0.001; Oman type . (Gulf-type ¼
Arabian Sea-type, p . 0.05), p , 0.05].
Abundance patterns were not reflected in biomass differences
among communities [Figure 5a; nested ANOVA F(2, 147) ¼ 16.5,
p , 0.001]. There was significantly less biomass in Gulf-type communities than in Oman- and Arabian Sea-type communities
(Unequal-N HSD, p , 0.001 each), which were comparable with
each other (p . 0.05). This difference reflects both the greater
abundance of fish in Oman-type communities (Figure 4) and
the relatively greater abundance of larger fish in Arabian
Sea-type communities (Figure 5b) than in Gulf-type communities.
The greater distribution of fish in the Arabian Sea was mainly
attributable to the endemic parrotfish, Scarus zufar (Scaridae),
which made up 46% of the abundance of the 17 fish species
observed in size classes ≥35 cm in the region.
The relative abundance of fish in different functional groups
differed substantially between each of the three community types
(Figure 6). Gulf-type communities were dominated by herbivores
and predators, which together constituted 98% of all fish observed.
Herbivores in the Gulf were dominated by herbivorous damselfish,
with two species (P. aquilus and Platyplectrurus trilineatus)
together making up .99% of abundance and L. ehrenbergii
(Lutjanidae) 43% of all predators. Planktivores were the most
abundant functional group in Oman-type communities, making
up nearly half (49%) of the community (Figure 6). This planktivore community
primarily consisted
of
damselfish
C. xanthopterygia (49% of planktivores) and Pomacentrus leptus
(38% of planktivores). There was a more equal distribution of
fish among functional groups in the Arabian Sea, although macroinvertivores, mainly T. lunare (Labridae; 44% of macroinvertivores) and Odonus niger (Acanthuridae; 37%), were more
common there than in other regions.
Overall, there was a significant positive relationship between
fish abundance and coral cover among sites (r 2 ¼ 0.32; t ¼ 2.7,
p , 0.05), but this was mainly attributable to high coral cover
and fish abundance at one site, Coral Garden (Table 1,
Figure 4). Excluding that site from the analysis, fish abundance
was not significantly related to coral cover (r 2 ¼ 0.09; t ¼ 1.4,
p . 0.05). Among community types, the strength of association
of fish with live coral varied [Figure 7; nested ANOVA F(6,
567) ¼ 73.7, p , 0.001]. In Gulf-type communities, ,2% of
fish were highly associated with live coral, significantly less
than fish with low or medium coral association (unequal-N
HSD, p , 0.001 each). This was mainly due to the high abundance of the low coral-associated species L. ehrenbergii
(Lutjanidae), which was the most common fish observed on
Arabian Gulf reefs (30% of total fish abundance). However,
in both Oman- and Arabian Sea-type communities, more
than 75% of the fish had a medium strength of association
with coral, significantly more than fish with low or high
strength coral association (Figure 7; p , 0.001 each). In both
regions, this was mainly due to the abundance of wrasses (T.
lunare in both areas) and damselfish (Oman-type: mainly C.
xanthopterygia and P. leptus; Arabian Sea: mainly C. xanthopterygia and P. aquilus) that have only moderate coral association,
which together constituted 67 and 43% of all moderately
coral-associated fish in the Gulf of Oman and the Arabian
Sea, respectively. There were significantly more fish with high
coral association in Oman-type communities than in both
Gulf and Arabian Sea types ( p , 0.05 each), which did not
differ between each other.
1880
J. A. Burt et al.
Figure 5. (a) Mean fish biomass (+s.e.; kg ha21) at each site in each community type, and (b) relative abundance (%) of fish in each size class
for each community type (note the log-scale).
Discussion
Reef fish communities of the northeastern Arabian Peninsula have
been suggested to be a distinct biogeographic unit (Smith and
Saleh, 1987; Smith et al., 1987; Kemp, 1998), separated from
those in the Red Sea and wider Indian Ocean by a zoogeographic
barrier at the Gulf of Aden (Kemp, 1998). A similar biogeographic
separation of northeast Arabian communities has been suggested
for corals (Sheppard, 1987, 1998; Sheppard and Sheppard,
1991), echinoderms (Price, 1982), and other fauna and flora
(Sheppard et al., 1992). The results of this study demonstrate substantial differences in reef fish communities within the northeastern Arabian biogeographic province, with reef fish falling into
three distinct subregional communities represented by sites
within the three major water bodies: the Persian Gulf, the Gulf
of Oman, and the Arabian Sea.
Biogeographic patterns of reef fish community structure in the NE Arabian Peninsula
Figure 6. Relative abundance (%) of fish in each functional guild.
Figure 7. Mean abundance (+s.e.; ha21) of fish categorized by the
strength of their association with coral for each community type.
The division of fish communities into the three geographic
subregions reflects patterns observed in other reef fauna. Coral
communities in the northeastern Arabian Peninsula are a
broadly overlapping assemblage that is distinct from those in the
wider Indian Ocean, but they do show subregional differences
among the Persian Gulf, the Gulf of Oman, and the Arabian Sea
similar to those shown here for reef fish (Sheppard, 1987, 1998;
Sheppard and Salm, 1988; Sheppard and Sheppard, 1991;
Sheppard et al., 1992). In addition, community similarity values
for fish reflect those observed for corals (Sheppard and Salm,
1988; Sheppard et al., 1992), with Gulf of Oman and Arabian
Sea communities having the most similar community structure,
and Persian Gulf and Arabian Sea communities the least similarity,
reflecting the larger differences in distance and environmental
conditions between the latter two.
The distinctiveness of the reef fish communities in the three
biogeographic subregions is likely the result of both environmental
and oceanographic barriers. The southern Persian Gulf is characterized by extreme temperature ranges and salinity compared with the
other areas (Price et al., 1993), and the Arabian Sea is much cooler
(98C) and nutrient-rich during the summer monsoonal
1881
upwelling (Morrison et al., 1998); these conditions likely resulting
in divergent communities from those in adjacent regions by acting
directly on fish physiology as well as by indirectly influencing coral
communities on reefs in which fish live (Coles and Tarr, 1990;
Coles, 2003; Feary et al., 2010). However, the lack of association
between reef fish abundance and the quantity of live coral cover
among sites here indicates that differences in coral abundance
likely play a limited role in explaining the differences in fish communities among the regions. Although the environmental differences between the Gulf of Oman and the southern Arabian Sea
are less extreme, it is likely that the Ras Al Hadd jet, which forms
between these two contiguous coasts during the summer
monsoon season, acts as a barrier to dispersal, particularly given
that the spawning of many fish species coincides with the onset of
the monsoon (Claereboudt et al., 2005; McIlwain et al., 2006).
This jet is formed by the confluence of a southerly coastal current
in the Gulf of Oman and a northerly coastal current in the northern
Arabian Sea, resulting in a fast-moving (.1 m s21) front 30 km
wide that extends .100 km offshore to the east of Ras Al Hadd
(Elliott and Savidge, 1990; Böhm et al., 1999), effectively forming
a wall between the two regions during the recruitment period.
The maintenance of the biogeographic differences among the
Persian Gulf, Gulf of Oman, and Arabian Sea would also be facilitated by the presence of permanent eddies known for each subregions, which would entrain larvae for recruitment to reefs within
their natal region rather than facilitate advection between regions
(Pous et al., 2004; Thoppil and Hogan, 2010).
The southern Persian Gulf fish communities were characterized
by low species richness, abundance, and biomass, with communities dominated by herbivores and generalist predators that had
low affinity for coral. These characteristics reflect the environmental extremes in the Gulf, where the elevated salinity and
high summer temperature can have direct negative effects on
fish physiology and energetics (Munday et al., 2008; Feary et al.,
2010), as well as indirect effects resulting from the low coverage,
rugosity, and diversity of corals that form the fish habitat in the
Gulf (Sheppard et al., 1992). The absence of true coral reefs in
the southern Persian Gulf also explains the predominance of herbivores and the virtual absence of fish with a great degree of coral
affinity.
In contrast to the Persian Gulf, fish communities in the Gulf of
Oman had higher richness, abundance, and biomass, and most
fish were moderately to highly associated with corals. This in
part reflects the relatively greater abundance of coral in the Gulf
of Oman than in the other regions (Sheppard and Sheppard,
1991), with fish abundance and biomass estimates highest on
sites around the northern and eastern Musandam, where coral
cover and the presence of true reefs is greater than anywhere else
in the northeastern Arabian Peninsula (Sheppard and Salm,
1988; Salm, 1993). These patterns also reflect the upwelling of
highly productive nutrient-rich waters along the Oman coast
during summer, which provides resources to support an abundant
and diverse community dominated by planktivores.
Although the fish communities in the Gulf of Oman and the
Arabian Sea did overlap to a greater extent than either did with
the Persian Gulf and had comparable biomass and coral affinity,
each was still represented by distinct communities with 72% dissimilarity in structure. The Arabian Sea contained fewer but relatively larger fish than the Gulf of Oman, with more than six times
more herbivores, and greater species richness when rarefaction was
used to control for differences in abundance among regions.
1882
Upwelling is stronger and more consistent in the Arabian Sea than
in the Gulf of Oman, resulting in SST values that are substantially
(98C) cooler than in the Gulf of Oman (Morrison et al., 1998).
These cool summer temperatures in the Arabian Sea result in a
pseudo high-latitude effect, where benthic and fish communities
in the area are more representative of high-latitude subtropical
reefs than expected, and low-cover corals are interspersed among
stands of large brown algae (Sheppard and Salm, 1988; Sheppard
and Sheppard, 1991; Kemp, 1998). The high productivity of
these waters, the cooler temperatures, and the prevalence of algadominated reefs during the monsoon season likely explain much
of the difference between the Arabian Sea and the Gulf of
Oman. The presence of the Ras Al-Hadd jet forming a relatively
impermeable front at the intersection of these two water bodies
during the spawning season for a number of fish likely maintains
these ecological differences. These reef fish patterns reflect those
observed for holothurids (Claereboudt and Al-Rashdi, 2011) and
algae (Schils and Wilson, 2006), with the Ras Al-Hadd area
suggested as marking one of the sharpest biotic transition points
known in marine biogeography (Schils and Wilson, 2006).
Several of the fish species observed in the Arabian Sea (e.g.
Amphiprion omanensis and Scarus zhofar) are endemic to the
region (Randall, 1995), reflecting the endemism known for seastars, holothurids, abalone, and coral in the area (Bosch et al.,
1995; Claereboudt, 2006; Claereboudt and Al-Rashdi, 2011), and
further emphasizing the distinct nature of the biogeographic subregion. It is also possible that less fishing pressure at the Arabian
Sea sites may have contributed to the relatively larger number of
fish in larger size classes, and consequent elevated biomass, compared with sites in the Arabian Gulf and the Gulf of Oman.
Although the results of this study demonstrate substantial
differences in reef fish community structure around the northeastern Arabian Peninsula, further comparative work will be necessary
to determine the nature and the extent of these differences. The
data here represent samples from a single season, and there is evidence that fish abundance and composition can fluctuate substantially throughout the year in some of the areas examined (Coles
and Tarr, 1990; Burt et al., 2009), suggesting the need for further
research to determine the temporal stability of the patterns
observed. There are also substantial differences in coral and
other benthic community structure, cover, and rugosity among
the sites examined, each of which can have notable impacts on
fish community structure. Investigating the role of the benthic
community associated with environmental differences in structuring reef fish communities seems to be warranted. There is currently a limited understanding of the role that species-specific
physiological differences in tolerance to temperature or salinity
extremes play in structuring assemblages in the region, and
more work is necessary to establish its importance. Similarly,
although this study represents the largest-scale survey of reef fish
around the northeastern Arabian Peninsula to date, with 24 sites
spanning .3000 km of coastline, it is certainly not exhaustive.
Extensive reefs with abundant and diverse fish communities
exist in northeastern Saudi Arabia and along the southwestern
Iranian coast, with very different environmental conditions from
the southern Persian Gulf sites sampled here (McCain et al.,
1984; Price et al., 1993; Krupp and Al-Marri, 1996; Shokri et al.,
2005). It is likely that the transition in environmental conditions
with distance along the northwesterly inflowing currents from
the Gulf of Oman translate into a more gradual change in reef
fish community structure than observed here. This is reflected in
J. A. Burt et al.
observations by Coles and Tarr (1990) and Krupp and Al-Marri
(1996) in northern Saudi Arabia, that the most abundant species
were those more common in Gulf-type communities (e.g.
L. ehrenbergii and Pomacentrus trichourus) and Oman-type communities (e.g. Caesio varilineata and Acanthurus sohal), as found
in this study (Supplementary material). Sites in southern Iran
are even more similar to those in the Gulf of Oman, containing
several families not observed at the Gulf sites examined here
(e.g. Acanthuridae, Balistidae, and Ostraciidae), but still containing an abundance of the species common in the Gulf-type communities here (Supplementary material), e.g. Pomacanthus
maculosus (Rezai and Savari, 2004). Further research into the physical, oceanographic, and biological factors structuring reef fish
communities in the region will be necessary to address these
gaps in knowledge.
Supplementary material
Supplementary material is available at the ICESJMS online version
of this manuscript as Table S1, a listing of the species composition
and abundance of fish communities in major water bodies around
the northeastern Arabian Peninsula.
Acknowledgements
We thank the following people and organizations that supported
this work: E. Grandcourt, A. Al-Cibahy and the Environment
Agency –Abu Dhabi, M. K. Shuriqi and Eng. A. Qasem and the
Fujairah Municipality, L. H. Al-Kharusi and the Oman Ministry
of Environment and Climate Affairs, Extra Divers Musandam
and T. Adriaens, Blue Planet Tourism Musandam, Al Sawadi
Beach Resort, Oman Dive Centre, R. Baldwin and S. Wilson and
Five Oceans Environmental Consultancy, F. and M. Vieira,
H. Kleijn, and R. and G. Thornycroft. The work was carried out
under the auspices of the Nakheel – UNU–INWEH joint
project “Strategic Management of Marine Ecosystems in Nakheel
Projects” as part of baseline data collection.
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