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Monitoring of South Sinai coral reefsinfluence of natural and anthropogenic factors.

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AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS
Aquatic Conserv: Mar. Freshw. Ecosyst. 18: 1109–1126 (2008)
Published online 10 April 2008 in Wiley InterScience
(www.interscience.wiley.com) DOI: 10.1002/aqc.942
Monitoring of South Sinai coral reefs: influence of natural and
anthropogenic factors
V. TILOTa,*,y, W. LEUJAKb, R. F. G. ORMONDb, J. A. ASHWORTHb,c and A. MABROUKd
a
Muse´um National d’Histoire Naturelle, De´partement des Milieux et Peuplements Aquatiques, 55 Rue Buffon, 75005 Paris, France
b
University (of London) Marine Biological Station Millport, Isle of Cumbrae, Scotland KA28 0EG, UK
c
Natural England, Northminster House, Peterborough, England, PE1 1UA, UK
d
South Sinai Protectorates, Egyptian Environmental Affairs Agency, Sharm El Sheikh, South Sinai, Egypt
ABSTRACT
1. To monitor any impacts to coral reefs related to the exponential growth of tourism in the South Sinai region
of the Egyptian Red Sea, nine stations were established at key reef sites over 2002–2003. At each station coral
cover was determined using a video survey method at depths of 3, 7 and 16 m, and fish abundance by underwater
visual census at depths of 3 and 10 m.
2. Mean total coral cover (hard plus soft) ranged from 58% to 23% at 3 m, 50% to 14% at 7 m, and 52% to
13% at 16 m, and hard coral cover from 37.5% to 15.7% at 3 m, 32.8% to 7.0% at 7 m, and 17.8% to 2.2% at
16 m. Analyses confirmed differences in coral assemblage related to depth and wave exposure.
3. Fish abundances and assemblages also varied with depth and proximity of deep water. Also the one site
subject to fishing had lower abundances of some commercial fish families and greater abundances of some
herbivores.
4. Transects subject to greater tourist use did not segregate from those subject to less tourist use, despite
evidence from other work of an effect from visitor damage to corals at some sites. This may be because visitors
were more attracted to sites that had higher coral cover.
5. Comparison of the present data with that from past studies is difficult because of the differences in sites and
method employed, but several observations suggest a moderate decline in coral cover during recent decades. Such
a decline would be compatible with the recorded impact of an outbreak of crown-of-thorns starfish, Acanthaster
planci, as well as with other evidence of accumulating damage by visitors.
6. Further monitoring using the same stations and consistent protocols is urgently required.
Copyright # 2008 John Wiley & Sons, Ltd.
Received 28 January 2007; Revised 7 September 2007; Accepted 16 November 2007
KEY WORDS:
coral reefs; reef monitoring; video transects; South Sinai; Gulf of Aqaba; Red Sea; visitor impacts; reef fisheries
*Correspondence to: Dr Virginie Tilot, Muséum National d’Histoire Naturelle, Département des Milieux et Peuplements Aquatiques, 55 Rue
Buffon, 75005 Paris, France. E-mail: v.tilot@wanadoo.fr
y
The order of the authors, as listed, does not necessarily reflect their respective contributions to the work reported.
Copyright # 2008 John Wiley & Sons, Ltd.
1110
V. TILOT ET AL.
INTRODUCTION
At its northern end, the Red Sea is divided by the southern
part of the Sinai Peninsula into two gulfs. On the western side,
the Gulf of Suez is broad and shallow, and in consequence
possesses only poorly developed coral communities. To the
east, however, the Gulf of Aqaba, though narrower, is much
deeper, and characterized by well-developed fringing reefs
along almost its entire shore (Bemert and Ormond, 1981). In
addition, at its southern entrance, in the Strait of Tiran, where
a 250 m deep sill separates the Gulf of Aqaba from the Red Sea
proper, lie four offshore reefs (Sheppard et al., 1992), and
around the southern tip of Sinai, at Ras Mohammed, a
precipitous fringing reef; these two sets of reefs are generally
regarded as among the world’s premier diving sites. Until the
1970s South Sinai lacked any large settlement, and these reefs
were unexploited, save by a few Bedouin tribes who fish there
mainly during the summer. Since then, however, the
attractions of scuba diving and snorkelling have stimulated a
dramatic expansion of the once Bedouin villages of Sharm El
Sheikh, Nuweiba and Dahab into major tourist resorts. By
1990 South Sinai was receiving 160 000 tourists per year
(Hawkins and Roberts, 1994; Jeudy de Grissac, 1999), but by
2002 this number had risen to 1.7 million per year, and by 2003
to 2 million per year, of whom most were concentrated in and
around the coastal city of Sharm El Sheikh (Jeudy de Grissac,
1999; SEAM, 2004b; Jobbins, 2006).
Although the proportion of visitors coming to dive has
slowly declined, in 2004, 21% of tourists came mainly to dive,
and a further 35.7% for snorkeling and other water sports
(SEAM, 2004a). Consequently the Egyptian authorities have
considered maintaining the quality of reefs as critical to the
economic growth of the region. Accordingly a network of
marine protected areas has been established that cover the
whole of the Egyptian Gulf of Aqaba’s reefs and coastline.
These include the Ras Mohammed National Park (NP) (which
includes the isolated reefs in the Straits of Tiran, and the
fringing reefs fronting Sharm El Sheikh, as well as the Ras
Mohammed peninsula), the Nabq Managed Resource
Protected Area (MRPA) to the north of Sharm El Sheikh,
and the Abu Galum MRPA to the north of Dahab.
Development affecting the protected areas is forbidden, as is
the discharge of any pollutant, including sewerage. In addition
throughout the Ras Mohammed NP fishing is prohibited,
although elsewhere small-scale artisanal subsistence fishing by
Bedouins is permitted, though strictly regulated, including
through the demarcation of no-take zones (Pearson and
Shehata, 1998; Galal et al., 2002).
Despite protective measures there has been concern that the
rapid development of the coast is having both direct and
indirect impacts to the area’s marine environment. In particular,
studies have recorded damage to corals by divers and
Copyright # 2008 John Wiley & Sons, Ltd.
snorkellers at the most popular sites (Hawkins and Roberts,
1992a,b, 1993, 1994; Medio and Ormond, 1995; Leujak, 2006;
Leujak and Ormond, in press a). At Sharm El Sheikh the reef
areas that are most heavily used by visitors have higher numbers
of broken hard coral colonies, loose coral fragments and partly
dead corals than do less heavily used areas (Hawkins and
Roberts, 1992b; Medio, 1996; Leujak, 2006). In addition,
apparently natural stressors, including rainwater floods carrying
sediment, coral diseases and crown-of-thorns starfish
(Acanthaster planci) outbreaks, have been apparent, with, in
particular, the east side of Ras Mohammed, the Tiran Straits
reefs, and sections of the coast north to Dahab being affected by
A. planci outbreaks between 1998 and 2002 (Salem, 1999;
Mabrouk, unpublished data). More generally, across the most
popular tourist sites it has been suggested, based on subjective
observation, that the loss of live coral cover owing to the
activities of visitors might have amounted to as much as 20% of
original cover (SEAM, 2004a).
Meanwhile a series of studies have described the structure
and zonation of coral communities in the Gulf of Aqaba (Loya
and Slobodkin, 1971; Loya, 1972; Mergner and Schuhmacher,
1974; Kotb et al., 1996, 2001). Similarly, reef fish assemblages
in the Red Sea and Gulf of Aqaba have been described by
various workers (Botros, 1971; Fishelson et al., 1974; Ormond
and Edwards, 1987; Roberts and Ormond, 1987; Roberts
et al., 1992; Roberts and Polunin, 1992; Khalaf and Kochzius,
2002). However, few of these studies have been carried out in
such a way as to provide the site-specific baseline data required
to benchmark an effective reef monitoring programme.
Further, recent studies in South Sinai have used a
bewildering array of methods, so that to date no clear
indication concerning changes in reef health over time exists
(Medio and Ormond, 1995; Kotb, 1996; Kotb et al., 1996,
2001; Medio, 1996; Tilot et al., 2000; Hassan et al., 2002). Thus
there has been a growing need to establish a standardized longterm monitoring programme for the region.
A pilot effort to initiate such long-term monitoring was
made in 1996 (Ormond, 1996), when still-photography was
used to assess permanent transects at stations distributed from
Ras Mohammed (at the southern tip of Sinai) to Taba
(adjacent to the border with Israel). However, due to changes
in personnel and lack of funding the proposed biennial
monitoring did not take place, nor, for administrative and
other reasons, have the results been published. Only in 2002
was a long-term Gulf of Aqaba Monitoring Programme
(GAMP) launched (Tilot, 2003). It was, however, determined
that the coral survey method should be changed, and a video
technique adopted, since a detailed comparison of six different
survey methods (Leujak and Ormond, in press b) had
concluded that this method would be the most cost-effective.
The new programme had the twin aims of (a) establishing with
a sufficient degree of accuracy and precision the abundances of
Aquatic Conserv: Mar. Freshw. Ecosyst. 18: 1109–1126 (2008)
DOI: 10.1002/aqc
MONITORING OF SOUTH SINAI CORAL REEFS
corals and reef fish on key reef sites in South Sinai, and (b)
assessing whether these amounts were likely to present a
significant change from historical values. It is the results of this
work that the present paper describes.
METHODS
Study sites
Nine permanent monitoring stations were assessed between
August 2002 and July 2003, four within the Ras Mohammed
NP, two on the reefs fronting Sharm El Sheikh, one on one of
the offshore reefs in the Straits of Tiran, one on the reefs
fronting the smaller resort town of Dahab, and one adjacent to
the northern border of the Nabq MRPA, not far from Dahab
(Figure 1). Stations were selected to represent contrasting
topographies (ranging from shallow sandy slopes to steep clifflike faces), varying degrees of exposure to wave action, and
different levels of impact from tourism (including intensively
used and less intensively used locations and fully closed areas),
so that any effect of natural and anthropogenic impacts on
coral and fish assemblages might be apparent.
Coral surveys
At each station three permanently marked 50 m long transects
were established, running parallel to the reef slope and
1111
following the depth contour, at each of three depths, 3, 7
and 16 m (i.e. nine transects per station). The depths were
chosen to represent the three apparent socio-topographic
zones (reef edge, reef face and reef slope), and to enable the
detection of impacts characteristic of each zone. Stations were
permanently marked with stainless steel rods at the start of
each transect, and large plastic screws inserted into drilled
holes at 5 m intervals along the transect. During monitoring a
50 m measuring tape was laid successively along each transect,
and held in place by plastic wire clips attached to each screw.
Transects were filmed with a digital video camera (Sony
3CCD-90) in an underwater housing (Amphibico). During
filming the camera was held perpendicular to the reef at a
distance of approximately 20 to 25 cm from the substratum,
and moved along the transect by swimming slowly at a speed
of 7 m min1. To analyse the video record a minimum of 90
still frames was sampled within each 50 m transect, and within
each frame the substratum underlying five regularly arranged
points (one central, and one towards each corner) recorded
(giving 1350 points sampled per depth contour per station).
This protocol was selected following previous work, which
demonstrated that this sampling effort was optimal, yielding a
minimum detectable difference of +/20% (i.e. an amount
equal to 20% of the original substrate cover value, not 20% on
top of or less than the original value) with a statistical power of
80% and an a-level of 0.05 (Leujak and Ormond, in press b).
Although a relative change in substrate cover of 20% of the
original value may not seem small, power analysis shows that
Figure 1. Maps of the Southern Sinai peninsula showing the locations of the nine monitoring stations (a) in the Ras Mohammed NP, the Sharm El
Sheikh area, and the Straits of Tiran, and (b) at Dahab and in the Nabq MRPA.
Copyright # 2008 John Wiley & Sons, Ltd.
Aquatic Conserv: Mar. Freshw. Ecosyst. 18: 1109–1126 (2008)
DOI: 10.1002/aqc
1112
V. TILOT ET AL.
it is a smaller difference than most reef monitoring protocols
are able to detect (Leujak, 2006). Moreover it is questionable
whether smaller differences, even if statistically significant, are
likely to be ecologically significant, in the sense of reflecting a
change that is likely to amount to more than normal interannual variation.
As in most coral monitoring studies, and in all surveys using
video techniques, hard and soft corals were identified to genus
and growth form, but, because of the limited resolution of the
video images, not always to species level. This restriction still
permits detection of change in coral abundance or coral
assemblage structure. On the other hand the time required to
achieve in situ identification of all corals to species level is so
great that it greatly reduces the length of transects that can be
monitored per unit time, and hence the power of monitoring to
detect significant change. Abiotic substrata recorded included
sand, rubble and coral rock. For algae a distinction was made
between macroalgae (>1 cm in height), coralline algae and turf
algae (0.5 cm to 1 cm in height). Coral rock colonized by a very
fine algal turf (50.5 cm height) could not be distinguished
from bare coral rock on the video image.
Underwater visual census of fish
Fish abundances at each station were estimated by underwater
visual census along four contiguous 50 m transects at depths of
3 and 10 m, the first transect at each depth beginning at the
same point as the first coral transects at each depth, and
continuing beyond the last one. Fish were counted within 5 m
either side of the observer’s path, yielding a measured area of
2000 m2 at each depth, and a total survey area of 4000 m2 per
station. Counts were also timed to obtain a standardized
swimming speed of 10 m min1. Only selected families of reef
fish that were considered commercially or ecologically
important and that were readily detectable within 5 m, were
counted. These included those targeted by Bedouin fisheries
(Lutjanidae, Scaridae, Serranidae, Siganidae, Lethrinidae,
Haemulidae, Acanthuridae), others identified as predators of
crown-of-thorns starfish (Balistidae, Tetraodontidae), and
others considered to be potential indicators of reef health
(Chaetodontidae, Pomacanthidae). Each observer normally
counted no more than two or three families of fish of similar
size and behaviour at any one time, allowing for more accurate
counting than when all or many families are counted at one
time (Ashworth and Ormond, 2005). Four 50 m transects were
used rather than three, since while for coral surveys three was
found to be the most cost-effective number of transects for
detecting differences between stations (Leujak, 2006), sets of
four 50 m transects had been used as standard during extensive
previous reef fish census work in the region (Galal et al., 2002;
Ashworth and Ormond, 2005). Depths of transects were
different for fish and coral work since videoing recorded
Copyright # 2008 John Wiley & Sons, Ltd.
substrate over a band less than 1 m in width, fish counts
recorded fish across a band 10 m wide that could readily
encompass two or more coral transects.
Data analysis
Means and standard deviations of percentage cover of each
benthic substratum type and of abundance of each fish family
and species were calculated for each depth at each station.
Univariate analysis was performed to look for differences in
abundance and species richness of substratum types (coral,
etc.) and fish between depths and stations. Data were first
tested for normality and homogeneity of variance using
Anderson–Darling and Levene‘s tests, and since in most
cases the assumptions of parametric statistics could not be met,
even with transformation of data, non-parametric Mann–
Whitney and Kruskal–Wallis tests were generally used.
Multivariate analyses of coral and fish assemblages were
conducted using the PRIMER (Plymouth Routines in
Multivariate Ecological Research) software package (Clarke,
1993; Clarke and Warwick, 2001). Non-metric MDS (multidimensional scaling) ordinations were used to display the data,
and one-way ANOSIM (Analysis of Similarity) and SIMPER
(Similarity Percentage) tests to assess differences and
similarities between datasets from different depths and sites.
Spearman’s rank-order correlations were used to investigate
trends in hard coral abundance over time.
1996 pilot survey
The 1996 pilot monitoring programme recorded 12 stations
distributed from Ras Mohammed to Taba (Ormond, 1996). At
each station 18 permanent quadrats placed 5 m apart were
recorded along single 100 m transects located at each of three
depths: 1, 8 and 15 m. Quadrats were photographed using a
Nikonos V camera, and substratum cover determined from the
photographs using image analysis software. Initially it was
intended in the present study to re-monitor the stations
established in 1996, but reduced funding allowed for only a
smaller number of stations. Further, because of the time that
had elapsed, the old markers could only be relocated at two
locations, Aqaba Beach and Jackson Reef, so that only for
these two stations has a direct comparison of 2002/2003 and
1996 data been possible.
RESULTS
Coral abundance
Across all sites mean hard coral cover was found to decrease
with increasing depth from 29.8% at 3 m to 11.8% at 16 m
Aquatic Conserv: Mar. Freshw. Ecosyst. 18: 1109–1126 (2008)
DOI: 10.1002/aqc
MONITORING OF SOUTH SINAI CORAL REEFS
(Figure 2(a)). Mean soft coral cover showed the opposite
trend, with an increase from 5.5% at 3 m to 14.7% at 16 m.
More than half of the benthic substratum was abiotic rock,
sand or rubble, total amounts of abiotic substratum increasing
with depth from 52.0% at 3 m to 69.9% at 16 m. Cover of
macroalgae and turf algae, by contrast, decreased with
increasing depth from 3.4% to 0.7%.
Total live coral cover (hard and soft corals, including
Millepora spp. and Tubipora spp.) at 3 m depth ranged from
58.4% to 22.5%, being highest at Jackson Reef and lowest at
Aqaba Beach (Table 1). At 7 m depth, total live coral cover
ranged from 55.0% at Jackson Reef to 13.6% at Aqaba Beach,
and at 16 m depth from 51.8% at Jackson Reef to 12.7% at
Aqaba Beach. At 3 m depth, highest hard coral cover was
recorded at Ras Um Sidd (37.5%) and Jackson Reef (36.5%),
at 7 m at Dahab Islands (32.8%) and at 16 m at Dahab Moray
Eel House (17.8%). At all depths hard coral cover was lowest
at Aqaba Beach (15.7%, 7.0% and 2.2% at 3, 7 and 16 m,
1113
respectively). Soft coral cover at all depths was highest at
Jackson Reef (14.8%, 33.3% and 38.3% at 3, 7 and 16 m,
respectively), and lowest at 3 and 7 m at Dahab Moray Eel
House (0.7%) and at 16 m at Marsa Bareika Mooring (5.8%).
Highest cover of algae (predominantly coralline algae) was
recorded at Aqaba Beach at all depths (11.5% at 3 m to 0.7%
at 16 m). Millepora spp. were most abundant at 3 m depth at
Marsa Bareika Mooring (10.5%), at 7 m at Aqaba Beach
(4.1%) and at 16 m at Jackson Reef (1.7%).
Pooling data from all sites, massive corals were the
dominant growth form at all depths (Figure 2), with their
proportional cover (i.e. their cover as a percentage of hard
coral cover, rather than as a percentage of the whole substrate)
being greatest (49.2%) at 7 m. The proportional cover of
branching corals decreased with depth from 39.3% at 3 m to
27.6% at 16 m, while by contrast, that of encrusting corals
increased with depth from 10.6% at 3 m to 15.0% at 16 m, as
did that of foliose coral, from 1.1% to 7.7%. However, these
trends were not consistent across stations. In particular,
variation with degree of exposure (to wave action) was
evident, with at 3 m the most exposed stations (Aqaba
Beach, Jackson Reef and the two Dahab sites) showing
dominance by branching corals, and semi-exposed and
sheltered stations showing dominance by massive corals at
this depth. At 16 m massive corals were dominant over
branching corals at all stations, except Aqaba Beach and
Dahab Islands. Massive coral proportional cover was highest
at Sheikh Coast at all three depths (77.3%, 79.9% and 73.5%
at 3, 7 and 16 m, respectively) and lowest at Aqaba Beach at all
three depths (9.5%, 21.4% and 26.1% at 3, 7 and 16 m,
respectively). Branching coral proportional cover was highest
at the Islands in Dahab at 3 m (63.5%) and 16 m (65.4%) and
at Dahab Moray Eel House at 7 m (49.5%).
Coral assemblage characteristics
Figure 2. Mean cover of (a) major substratum categories, and (b) hard
coral growth forms, at 3 m, 7 m and 16 m depth across all nine
monitoring stations. Error bars show standard deviations. The
category ‘other’ includes other organisms such as molluscs, sponges,
zoanthids etc.
Copyright # 2008 John Wiley & Sons, Ltd.
At the majority of stations the dominant coral genus at 3 m
depth was Porites, followed by Acropora (Table 2), save at the
most exposed stations (Aqaba Beach, Jackson Reef and the
two at Dahab) where Acropora spp. were dominant. Other
dominant genera were Pocillopora, Montipora, Goniastrea and
Platygyra. The dominant soft coral taxa varied more between
stations, with either xeniids, or Litophyton, or Sinularia or
Lobophyton being most abundant. At 7 m depth Porites was
the dominant hard coral genus at all stations, except Aqaba
Beach and Dahab Moray Eel House, where Montipora and
Acropora, respectively, were dominant, and xeniids were the
dominant soft coral taxon, with their cover reaching 22%. At
16 m the most abundant hard coral genus varied between sites,
being Goniastrea, Montipora, Seriatopora, or Porites; but
whichever was most abundant its absolute cover was low, with
Aquatic Conserv: Mar. Freshw. Ecosyst. 18: 1109–1126 (2008)
DOI: 10.1002/aqc
1114
V. TILOT ET AL.
Table 1. Mean percentage substratum cover of hard corals, soft corals and other benthic substratum categories, and of individual hard coral growth
forms, at each of the nine stations and three depths. The locations of the stations are indicated by column headings as follows: AQ ¼ Aqaba Beach;
TB ¼ Turtle Beach; MM ¼ Marsa Bareika Mooring; MS ¼ Marsa Bareika South; RS ¼ Ras Um Sidd; SK ¼ Sheikh Coast; JK ¼ Jackson Reef;
DIS ¼ Dahab Islands; DMO ¼ Dahab Moray Eel House: SD ¼ standard deviation for mean values in preceding column. The most exposed stations
are AQ, JK, DIS and DMO. The most sheltered stations are MM and MS
3m
AQ
SD
TB
SD
MM
SD
MS
SD
RS
SD
SK
SD
JK
SD
DIS
Hard coral
Soft coral
Abiotic
Algae
Other
Millepora spp.
Branching
Encrusting
Foliose
Massive
Free-Living
Submassive
Tabulate
15.7
3.2
55.4
1.9
3.6
3.6
8.0
0.9
0.4
1.5
0.0
0.5
4.5
3.0
2.9
4.0
1.8
3.5
3.5
4.0
0.7
0.6
0.5
0.0
0.4
1.6
34.1
3.4
49.3
0.7
4.1
4.1
13.1
2.7
0.6
15.8
0.1
0.0
1.8
3.3
2.7
4.1
0.6
1.6
1.6
0.5
0.5
1.1
2.3
0.1
0.0
1.2
28.0
1.7
55.9
0.3
10.5
10.5
9.4
3.3
0.4
11.8
0.3
0.0
2.8
0.5
0.5
2.1
0.2
2.0
2.0
2.6
0.3
0.3
3.2
0.4
0.0
1.7
25.2
2.0
60.6
0.1
8.6
8.6
6.3
3.2
0.2
14.9
0.2
0.1
0.4
4.3
1.1
1.9
0.1
1.8
1.8
1.8
1.1
0.4
2.4
0.2
0.1
0.6
37.5
5.8
46.5
0.4
4.2
4.2
10.5
4.9
0.2
21.2
0.0
0.0
0.7
13.1
1.9
11.6
0.4
0.4
0.4
2.7
0.6
0.4
9.4
0.0
0.0
0.5
32.5
11.7
49.7
0.2
3.3
3.3
4.6
2.5
0.1
25.2
0.1
0.0
0.1
11.2
0.6
9.4
0.2
0.6
0.6
2.1
0.6
0.1
12.1
0.1
0.0
0.1
36.5
14.8
37.1
0.7
7.1
7.1
18.5
4.6
0.1
12.5
0.0
0.1
0.7
5.8
5.7
4.9
1.0
3.6
3.6
3.5
1.4
0.1
7.7
0.0
0.1
1.1
32.0
9.0
50.1
0.1
3.0
3.0
20.4
3.7
0.2
7.0
0.1
0.0
0.6
7m
AQ
SD
TB
SD
MM
SD
MS
SD
RS
SD
SK
SD
JK
SD
DIS
Hard coral
Soft coral
Abiotic
Algae
Other
Millepora spp.
Branching
Encrusting
Foliose
Massive
Free-Living
Submassive
Tabulate
7.0
2.5
73.7
2.0
1.0
4.1
1.1
3.2
0.3
1.5
0.0
0.1
0.9
4.2
1.2
2.5
1.3
0.4
3.3
1.1
1.4
0.3
1.0
0.0
0.2
1.0
22.8
14.7
54.8
0.7
0.6
3.6
10.0
2.1
0.0
8.8
0.7
0.0
1.3
5.4
2.8
2.8
0.6
0.7
2.8
1.0
1.3
0.0
4.9
0.5
0.0
1.1
15.9
1.9
78.3
0.0
0.4
1.0
6.5
1.8
0.2
6.7
0.2
0.0
0.4
1.0
1.6
1.7
0.0
0.3
0.9
1.4
1.0
0.0
1.6
0.2
0.0
0.6
17.4
3.2
73.3
0.1
0.2
1.8
2.4
1.0
0.4
13.0
0.5
0.0
0.0
9.3
0.5
9.7
0.1
0.3
0.3
2.1
0.6
0.8
8.4
0.4
0.0
0.0
18.1
23.1
54.6
0.4
0.1
0.6
3.1
3.9
0.0
10.7
0.4
0.0
0.0
18.2
33.0
43.6
0.1
0.3
3.8
7.1
2.6
0.1
8.0
0.2
0.1
0.2
7.3
2.1
4.8
0.1
0.3
0.3
1.0
0.6
0.1
6.1
0.4
0.1
0.3
16 m
AQ
SD
TB
SD
MM
SD
MS
SD
RS
JK
Hard coral
Soft coral
Abiotic
Algae
Other
Millepora spp.
Branching
Encrusting
Foliose
Massive
Free-Living
Submassive
Tabulate
2.2
9.7
84.0
0.7
2.1
0.9
0.7
0.4
0.5
0.6
0.0
0.0
0.0
1.6
2.1
5.7
0.4
1.0
0.5
0.5
0.3
0.5
0.8
0.0
0.0
0.0
15.3
16.3
65.4
0.1
0.9
0.7
3.9
3.6
0.1
6.2
0.1
0.0
1.5
3.1
3.5
3.7
0.2
0.1
0.4
0.6
1.8
0.1
0.6
0.1
0.0
0.9
15.4
5.8
75.4
0.1
1.0
0.4
3.2
2.5
0.1
8.8
0.2
0.0
0.7
2.9
6.4
5.8
0.1
0.9
0.1
0.3
0.9
0.1
1.7
0.1
0.0
0.6
15.7
13.9
66.7
0.0
0.5
1.2
2.5
1.8
3.0
7.3
0.0
0.0
1.1
3.3
2.5
3.7
0.0
0.9
0.7
0.7
0.6
1.7
1.1
0.0
0.0
1.9
6.8
19.0
71.6
0.2
1.3
0.3
1.6
2.4
0.0
2.3
0.2
0.0
0.4
11.8
38.3
43.0
0.4
3.1
1.7
3.4
2.0
0.1
5.0
0.0
0.2
1.1
hard corals being dominated by soft corals, among which
xeniids were again the most abundant.
Diversity of hard coral genera over all stations was highest
at 3 m with a mean 10.3 genera recorded per 50 m transect,
compared with 8.7 and 8.9 per 50 m at 7 and 16 m (Table 3). At
3 m genera diversity was highest at Jackson Reef, Turtle
Beach, Marsa Bareika Mooring, Dahab Moray Eel House and
Copyright # 2008 John Wiley & Sons, Ltd.
3.3
1.4
5.8
0.2
0.1
0.7
0.7
3.3
0.0
0.7
0.2
0.0
0.0
SD
2.0
2.1
2.0
0.3
0.7
0.4
0.7
0.7
0.0
1.5
0.1
0.0
0.7
11.7
13.1
72.6
0.0
0.1
0.1
1.1
0.9
0.1
9.4
0.2
0.0
0.0
SK
7.5
8.7
82.8
0.2
0.5
0.0
0.7
0.2
1.2
5.5
0.0
0.0
0.0
7.4
3.6
9.1
0.0
0.1
0.1
0.6
0.3
0.3
6.7
0.4
0.0
0.0
SD
5.2
2.6
7.0
0.1
0.3
0.0
0.7
0.3
2.0
2.5
0.0
0.0
0.0
SD
DMO
SD
26.8
0.8
63.2
0.3
8.0
8.0
18.7
1.3
0.1
5.4
0.4
0.0
0.9
3.3
0.9
3.8
0.3
3.3
3.3
3.5
0.8
0.1
0.9
0.4
0.0
1.4
SD
DMO
SD
32.8
10.0
52.4
1.8
0.2
0.4
13.4
2.6
0.1
16.2
0.1
0.0
0.3
12.7
9.0
6.3
1.5
0.4
0.4
4.8
3.7
0.3
13.4
0.1
0.0
0.6
20.7
0.7
76.2
1.8
0.4
0.2
10.3
2.5
0.6
7.0
0.4
0.0
0.0
6.6
0.5
6.6
0.3
0.5
0.2
7.7
1.3
1.0
1.4
0.3
0.0
0.0
SD
DIS
SD
DMO
SD
2.8
7.2
8.9
0.1
0.7
0.8
0.8
0.9
0.1
3.6
0.0
0.0
1.1
13.3
11.3
74.0
0.6
0.2
0.1
8.7
0.3
0.4
3.7
0.0
0.0
0.2
17.8
9.7
66.5
4.2
1.2
0.2
4.5
2.0
1.2
8.8
0.2
0.1
1.1
2.5
4.8
6.5
1.1
0.6
0.0
1.2
3.3
0.8
2.7
0.3
0.1
1.5
4.3
5.1
3.0
0.1
1.5
1.5
6.9
1.3
0.4
4.5
0.1
0.0
1.1
2.4
2.5
3.5
0.3
0.4
0.1
4.5
0.5
0.5
2.7
0.0
0.0
0.4
Dahab Islands (a mixture of exposed and sheltered sites),
whereas at 7 and 16 m depths it was highest at Marsa Bareika
Mooring. Genera diversity was lowest at 3 m at Aqaba Beach,
Ras Um Sidd and Sheikh Coast, at 7 m at Sheikh Coast, and at
16 m at Sheikh Coast and Aqaba Beach. By contrast, mean
Shannon–Wiener index increased with increasing depth
(Table 3) reflecting a greater evenness among coral
Aquatic Conserv: Mar. Freshw. Ecosyst. 18: 1109–1126 (2008)
DOI: 10.1002/aqc
1115
MONITORING OF SOUTH SINAI CORAL REEFS
Table 2. Mean percentage substratum cover at each depth at each station of the hard and soft coral genera and growth forms that were most
abundant at each of those locations. The stations are indicated by abbreviations as in Table 1. The most exposed stations were AQ, JK,
DIS and DMO
3m
Hard corals
AQ
TB
MM
MS
RS
SK
JK
DIS
DMO
3m
%
Tabular Acropora 4.5
spp.
Branching
3.9
Pocillopora spp.
Branching
3.0
Acropora spp.
Massive Porites 11.4
spp.
Branching
6.0
Acropora spp.
Branching
5.9
Pocillopora spp.
Massive Porites 8.0
spp.
Branching
4.7
Acropora spp.
Branching
3.6
Pocillopora spp.
Massive Porites 13.4
spp.
Branching
3.3
Pocillopora spp.
Encrusting
2.9
Montipora spp.
Massive Porites 18.7
spp.
Branching
5.7
Pocillopora spp.
Encrusting
4.3
Montipora spp.
Massive Porites 24.7
spp.
Encrusting
2.3
Montipora spp.
Branching
2.0
Acropora spp.
Branching
13.0
Acropora spp.
Massive Porites 10.3
spp.
Encrusting
3.0
Montipora spp.
Branching
15.7
Acropora spp.
Massive Porites 4.4
spp.
Branching
3.1
Pocillopora spp.
Branching
17.3
Acropora spp.
Massive
2.3
Goniastrea spp.
Massive
1.3
Platygyra spp.
Soft corals
7m
%
Lobophyton
spp.
Sinularia
spp.
1.7
Sinularia
spp.
Xeniidae
1.6
Xeniidae
0.8
Rhytisma
spp.
0.6
Sinularia
spp.
Xeniidae
1.2
0.5
Xeniidae
5.5
Sinularia
spp.
0.1
Xeniidae
11.7
1.4
1.3
8.0
Litophyton
spp.
Xeniidae
3.7
Xeniidae
6.8
Sinularia
spp.
1.3
Litophyton
spp.
Sinularia
spp.
Copyright # 2008 John Wiley & Sons, Ltd.
0.4
0.2
Hard corals
7m
%
16 m
Soft corals
Encrusting
2.0
Montipora spp.
Massive Porites 1.3
spp.
Encrusting coral? 1.2
Lobophyton
spp.
Xeniidae
Massive Porites 6.4
spp.
Branching
6.2
Acropora spp.
Branching
2.4
Stylophora spp.
Massive Porites 2.9
spp.
Branching
2.7
Acropora spp.
Branching
2.3
Pocillopora spp.
Massive Porites 12.4
spp.
Branching
1.7
Acropora spp.
Encrusting
0.9
Montipora spp.
Massive Porites 10.5
spp.
Encrusting
3.8
Montipora spp.
Branching
1.0
Acropora spp.
Massive Porites 9.2
spp.
Encrusting
0.9
Montipora spp.
Branching
0.8
Stylophora spp.
Massive Porites 6.5
spp.
Branching
4.6
Acropora spp.
Branching
1.8
Stylophora spp.
Massive Porites 15.8
spp.
Branching
10.4
Acropora spp.
1.5
Branching
Stylophora spp.
Branching
9.1
Acropora spp.
Massive
4.3
Goniastrea spp.
Encrusting
2.3
Montipora spp.
Xeniidae
%
1.3
0.4
12.8
Litophyton
spp.
1.3
Xeniidae
0.9
Rhytisma
spp.
0.4
Xeniidae
3.2
Xeniidae
Litophyton
spp.
Xeniidae
Sarcophyton
spp.
21.5
1.3
13.0
0.2
Xeniidae
16.0
Litophyton
spp.
12.5
Xeniidae
9.5
Lobophyton
spp.
Tubipora
spp.
Xeniidae
0.2
Rhytisma
spp.
0.2
0.4
0.1
Hard corals
16 m
%
Branching
0.4
Seriatopora spp.
Foliose Pachyseris 0.4
spp.
Encrusting
0.4
Montipora spp.
Encrusting
3.2
Montipora spp.
Massive
Porites 3.1
spp.
Branching Acropora 1.7
spp.
Massive Goniastrea 1.9
spp.
Massive
Porites 5.2
spp.
Encrusting
1.9
Montipora spp.
Massive
Porites 5.0
spp.
Massive Leptoseris 2.6
spp.
Encrusting
1.7
Montipora spp.
Encrusting
2.2
Montipora spp.
Massive
Porites 1.5
spp.
Branching
1.1
Stylophora spp.
Massive
Porites 3.8
spp.
Massive
1.2
Lobophyllia spp.
Massive Goniastrea 0.3
spp.
Massive Goniastrea 2.6
spp.
Branching
1.9
Stylophora spp.
Encrusting
1.5
Montipora spp.
Branching Acropora 5.7
spp.
Massive Alveopora 1.2
spp.
Branching
1.3
Pocillopora spp.
Massive Goniastrea 3.5
spp.
Branching Acropora 2.7
spp.
Massive
Porites 2.3
spp.
Soft corals
%
Xeniidae
9.2
Rhytisma
spp.
0.1
Xeniidae
12.0
Soft coral
2.1
Xeniidae
5.1
Litophyton
spp.
0.3
Xeniidae
Sarcophyton
spp.
Xeniidae
13.2
0.2
17.2
Litophyton
spp.
1.5
Xeniidae
8.1
Sarcophyton
spp.
0.3
Xeniidae
Litophyton
spp.
24.1
9.0
Xeniidae
11.2
Sinularia
spp.
0.1
Xeniidae
9.6
Anthipathes
spp.
0.1
Aquatic Conserv: Mar. Freshw. Ecosyst. 18: 1109–1126 (2008)
DOI: 10.1002/aqc
1116
V. TILOT ET AL.
Table 3. Number of hard coral genera and associated Shannon–Wiener diversity index (loge) for each depth at each station (abbreviations as in
Table 1)
Stations
Number of genera 3 m
H0 loge
Number of genera 7 m
H0 loge
Number of genera 16 m
H0 loge
AQ
TB
MM
MS
RS
SK
JK
DIS
DMO
Mean
SD
8
12
12
9
8
8
12
12
12
10.3
2.0
1.49
1.96
2.01
1.57
1.54
0.97
1.88
1.79
1.37
1.62
0.33
6
10
14
7
7
5
9
8
12
8.7
2.9
1.94
1.91
2.35
1.17
1.34
0.9
1.9
1.48
1.84
1.65
0.46
5
12
13
10
8
5
9
8
10
8.9
2.8
2.04
2.15
2.17
2.1
1.99
1.62
2.11
1.86
2.19
2.03
0.18
assemblages at depth, whereas in shallow water there was
strong dominance of certain hard coral genera. The highest
Shannon–Wiener diversity was recorded for 3 and 7 m at
Marsa Bareika Mooring, and for 16 m at Dahab Moray Eel
House. At all depths Sheikh Coast had the lowest diversity
index, probably reflecting the prevalence there of Porites.
A multi-dimensional scaling (MDS) plot of the data revealed
a degree of clustering in relation to depth (Figure 3(a)). The
3 m cluster is fairly well focused and well separated from the
16 m cluster; the 7 m cluster, however, is more dispersed,
overlapping those for both 3 and 16 m. At 3 and 7 m the
stations at Aqaba Beach and Dahab Moray Eel House are
outliers, as are the two Dahab stations at 16 m. A one-way
ANOSIM confirmed the strong similarities among transects at
each depth (global R ¼ 0:210; significance level 0.2%), and
that the largest dissimilarity was between the 3 and 16 m
transects (R ¼ 0:446; significance level 0.1%). Also, when
stations were classified according to degree of wave exposure,
marked clustering was evident among sheltered and semiexposed sites, although exposed sites showed a separation
between Aqaba Beach and Jackson Reef Stations (lower right)
on the one hand, and the Dahab Stations (at the top) on the
other (Figure 3(b)). By contrast, when stations were classified
according to levels of human impact (none, low, medium,
high) or topographic characteristics (slope steepness, or
fringing reef versus offshore), no obvious clustering was
evident in the MDS plots (Figure 3(c)).
Fish abundances
Across the stations the most abundant families observed at
both 3 and 10 m depths were Acanthuridae, Chaetodontidae
and Scaridae (Table 4). To limit the numbers of tables, data on
abundance at each site is not presented here, but at both
depths Acanthuridae were the most abundant family at all
sites, save at 3 m at Jackson Reef and at 10 m at Marsa Bareika
Mooring, at both of which Chaetodontidae were most
abundant, and at 10 m at Ras Um Sidd where Scaridae were
Copyright # 2008 John Wiley & Sons, Ltd.
most abundant. Among potential predators of crown-ofthorns starfish, Balistidae were absent at Dahab Islands, but
Tetraodontidae were abundant.
Among the fish families counted a total of 65 species were
recorded. Across all stations at 3 m the most abundant were
the surgeonfish Acanthurus nigrofuscus, the butterflyfish
Chaetodon austriacus, the surgeonfish Ctenochaetus striatus
and the parrotfish Scarus niger. A. nigrofuscus was the most
abundant at all stations except Marsa Bareika South, where C.
austriacus was more abundant. At 10 m C. striatus, A.
nigrofuscus, and S. niger were again the most abundant
species, together with the rabbitfish Siganus luridus. C. striatus
was the most abundant species at all stations except Turtle
Beach, Sheikh Coast and Dahab Islands, where A. nigrofuscus
prevailed. Species occurring at 3 m but absent at 10 m included
the surgeonfish Acanthurus sohal, the triggerfish Balistoides
viridescens, the seabream Acanthopagrus bifasciatus, the
emperors Lethrinus xanthochilus, L. borbonicus, and the
grouper P. pessuliferus marisrubri. Species occurring at 10 m
but not at 3 m included the emperor L. nebulosus, the angelfish
Genicanthus caudovittatus, and the parrotfishes Scarus collana
and Scarus albicaudatus.
Total fish abundances (Table 5) ranged from 97.3 (per
500 m2) at Marsa Bareika South at 3 m to 51.8 (per 500 m2) at
Dahab Islands at 10 m. It was significantly higher at 3 m (85
individuals per 500 m2) than at 10 m (64 per 500 m2) (Mann–
Whitney U test, P ¼ 0:002). Overall abundances varied
significantly at both depths (3 m H ¼ 16:64; DF ¼ 7; P ¼
0:026; 10 m H ¼ 17:50; DF ¼ 7; P ¼ 0:014), with Jackson Reef
and Aqaba Beach having significantly greater abundances than
most other sites at 3 m, and significantly lower abundances
than most other sites at 10 m.
Fish assemblage characteristics
Mean species richness (among the families counted) ranged
from 25.8 per 500 m2 at 3 m at Marsa Bareika South, to 13.3
per 500 m2 at 10 m at Dahab Islands. Mean species richness
Aquatic Conserv: Mar. Freshw. Ecosyst. 18: 1109–1126 (2008)
DOI: 10.1002/aqc
1117
MONITORING OF SOUTH SINAI CORAL REEFS
Table 4. Mean abundances per 500 m2 band transect at each depth
across all stations of each fish family counted. SD indicates standard
deviation
Figure 3. Multidimensional scaling plots (a) full benthic community
data at all nine stations and three depths, with letter codes indicating
location, and number indicating depth, and hard coral assemblage
data at 3 m and 7 m depth only, with transects designated (b) according
to degree of exposure of site to wave action, and designated (c)
according to intensity of visitor use.
was 20.5 at 3 m and 18.6 at 10 m (Table 5), but these values
were not significantly different (Mann–Whitney U test). A
Kruskal–Wallis test showed that at both depths there was
significant variation in species richness across the stations (3 m
H ¼ 14:86; DF ¼ 7; P ¼ 0:038; 10 m H ¼ 14:82; DF ¼ 7;
P ¼ 0:038), with pair-wise comparisons showing in particular
that at 3 m Marsa Bareika South had a higher species richness
than most other sites, and at 10 m Dahab Islands, a lower
species richness than most other sites. Shannon–Wiener
diversity index was highest at Marsa Bareika South at 3 m
Copyright # 2008 John Wiley & Sons, Ltd.
Family
Mean 3 m
SD
Acanthuridae (surgeonfishes)
Chaetodontidae (butterflyfishes)
Scaridae (parrotfishes)
Serranidae (groupers)
Pomacanthidae (angelfishes)
Siganidae (rabbitfishes)
Lutjanidae (snappers)
Haemulidae (sweetlips)
Balistidae (triggerfishes)
Tetraodontidae (pufferfishes)
Lethrinidae (emperors)
Sparidae (seabreams)
Mullidae (goatfishes)
Monacanthidae (filefishes)
38.9
20.5
10.8
4.2
3.0
1.9
1.3
1.2
1.1
0.8
0.7
0.2
0.1
0.0
13.3 21.8
5.4 11.8
4.2 12.4
2.1 6.3
1.7 5.1
1.7 2.5
1.8 0.3
1.7 0.0
0.7 1.5
0.9 0.3
0.7 1.7
0.4 0.0
0.4 0.1
0.1 0.1
Mean 10 m
SD
3.8
4.4
6.6
3.4
3.0
2.0
0.2
0.1
1.0
0.6
1.8
0.0
0.2
0.2
depth (Table 5), but was not significantly different between the
two depths.
An MDS plot of the fish data showed clear separation of the
clusters corresponding to 3 and 10 m depth transects (Figure
4), while a one-way ANOSIM confirmed significant differences
between the assemblages at these two depths (global R ¼
0:373; significance level 0.1%). SIMPER analysis showed that
14 species accounted for 50% of the distinction between the
two depths: the butterflyfishes Chaetodon austriacus (4.4%),
C. trifascialis (3.5%) and Heniochus intermedius (3.9%), the
groupers Cephalopholis hemistiktos (3.7%) and C. miniata
(3.2%), the angelfish Centropyge multispinis (3.7%), the
surgeonfishes A. nigrofuscus (3.5%), A. sohal (3.2%). and
Zebrasoma xanthurum (3.5%), the parrotfishes Chlorurus
sordidus (3.4%) and Scarus niger (3.2%), and the rabbitfish
Siganus luridus (3.3%). Further ANOSIM and SIMPER
analyses showed that the fish assemblages at both depths at
both Aqaba Beach and at Jackson Reef were significantly
different from those at all other sites.
Comparison of substratum and fish at 3 m, and of substratum
data at 7 m with fish data at 10 m (since the 10 m fish band
transect overlapped the 7 m substratum transect) revealed a
number of relevant findings. Neither overall fish abundances
nor overall fish diversity were significantly correlated with hard
coral cover (rs ¼ 0:071 and rs ¼ 0:200; respectively),
abundance even appearing to show a slight decline with
increasing hard coral cover. However, total abundances of
obligate corallivorous butterflyfishes (Chaetodon melannotus,
C. austriacus, C. paucifasciatus, C. trifascialis) showed a weak
but non-significant correlation with hard coral cover (Spearman
rank-order correlation rs ¼ 0:345; P ¼ 0:185), and the
abundance of C. austriacus was significantly correlated with
hard coral cover (rs ¼ 0:521; P ¼ 0:039).
Aquatic Conserv: Mar. Freshw. Ecosyst. 18: 1109–1126 (2008)
DOI: 10.1002/aqc
1118
V. TILOT ET AL.
Table 5. Mean (n ¼ 4) species richness (S), overall fish abundance (N) and Shannon–Wiener (H0 loge) index for fish within the families counted at
each depth (3 and 10 m) at each station (site abbreviations as in Table 1). SD indicates standard deviation
Station
S
SD
N
SD
H0 (loge)
SD
Station
S
SD
N
SD
H 0 (loge)
SD
AQ3
TB3
RS3
SK3
MS3
MM3
JK3
DIS3
Mean
SD
20.0
22.3
21.0
21.0
25.8
20.5
17.8
16.0
20.5
2.9
3.0
2.5
2.2
2.2
2.4
2.6
4.7
4.5
78.8
97.0
97.0
91.0
97.3
73.3
53.0
89.3
84.6
15.5
10.1
9.8
13.2
14.5
4.9
6.3
6.6
16.1
2.38
2.60
2.43
2.48
2.87
2.54
2.61
2.12
2.50
0.22
0.09
0.16
0.17
0.08
0.21
0.13
0.22
0.30
AQ10
TB10
RS10
SK10
MS10
MM10
JK10
DIS10
Mean
SD
17.3
19.3
20.3
22.0
20.3
20.3
16.3
13.3
18.6
2.8
2.4
1.6
3.0
3.4
2.6
3.0
2.6
1.7
56.3
58.0
76.5
73.8
68.8
72.3
55.3
51.8
64.1
9.7
11.8
7.4
20.3
12.3
8.1
16.5
11.4
6.2
2.55
2.65
2.68
2.76
2.68
2.68
2.46
2.17
2.58
0.19
0.21
0.19
0.12
0.23
0.17
0.16
0.14
0.18
Figure 4. Multidimensional scaling plots using log (x+1) transformed
data and Bray–Curtis similarities of fish data for each of four transects
at each depth (3 and 10 m) at each station designated to illustrate
segregation of transects according to (a) depth, and (b) fisheries status
(fished versus non-fished).
(34.3 individuals compared with 46.6 per 500 m2), but slightly
higher at 10 m (66.0 individuals compared with 62.4 per
500 m2) than at the unfished sites (Figure 5). At 3 m depth
Serranidae and Lethrinidae were significantly less abundant at
the fished station than at the others (Mann-Whitney U test:
W ¼ 56:0; P ¼ 0:010; and W ¼ 55:0; P ¼ 0:017; respectively),
and Acanthuridae significantly more abundant (W ¼ 28:0;
P ¼ 0:011). Similarly at 10 m depth Scaridae and Serranidae
were significantly less abundant than at other sites (W ¼ 56:0;
P ¼ 0:011 and W ¼ 56:0; P ¼ 0:010), and Siganidae
significantly more abundant (W ¼ 29:5; P ¼ 0:023). A oneway ANOSIM confirms a significant difference between fished
and non-fished stations (global R ¼ 0:632; significance level
0.1%), and inspection of the MDS plot (Figure 4(b)) shows
how the points representing transects at the Dahab Islands
station cluster separately from the points for all other stations.
A SIMPER analysis showed that a total of 14 species
accounted for 50% of the distinction between the fished station
at Dahab and the remaining stations closed to fishing, with the
most influential being the parrotfishes S. sordidus (4.5%) and
S. luridus (3.9%), the angelfish C. multispinis (4.2%), the
butteflyfishes C. austriacus (4.0%), C. trifascials (3.4%), and
H. intermedius (3.6%), the surgeonfish Zebrasoma desjardinii
(3.8%), the grouper C. miniata (3.5%), and the pufferfish
Arothron diadematus (3.4%). Twenty-seven species recorded at
other monitoring stations were not recorded at the fished
station, including four groupers, three snappers, three
emperors, and one sweetlips, all considered commercial
species.
Comparison with other surveys
Effects of fishing
Dahab Islands was the only monitoring station where fishing is
permitted. When the data for this site were compared with
those for all others it was found that overall fish abundance at
this fished site (within the families counted) was lower at 3 m
Copyright # 2008 John Wiley & Sons, Ltd.
Because the substrate data were collected using a different
method than that used in the 1996 pilot study, and the precise
locations of all save two stations were different, a
comprehensive comparison with the 1996 data was not
possible. However, data exploration revealed two findings of
Aquatic Conserv: Mar. Freshw. Ecosyst. 18: 1109–1126 (2008)
DOI: 10.1002/aqc
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MONITORING OF SOUTH SINAI CORAL REEFS
Figure 5. Mean abundances of fish families targeted by fishing at the two fished stations compared with mean abundances at the other non-fished
stations at 3 and 10 m depth. Error bars indicate standard deviations.
interest. At the two stations where the same transects were
surveyed in 2002 as in 1996, Jackson Reef and Aqaba Beach,
recorded hard coral cover was lower at all depths in 2002 than
in 1996 (Table 6). The apparent decrease in absolute hard coral
cover ranged from 5% to 36% and was greatest on the shallow
transects at both sites. At the same time soft coral cover
appeared to have increased by 0.5% to 10% on five of the six
transects, the exception being the deep transects at Jackson
Reef. Comparing coral genera data between the two years, it is
apparent that most of the decline at shallower depths was due
to a decrease in Acropora (Table 6), absolute cover of which
decreased by 24% at Aqaba Beach and 10% at Jackson Reef.
The same methods were used to assess fish abundance in
1996 and 2002/2003, but in order to obtain sufficient numbers
of replicates to compare sets of transects most of which were in
different locations, fish abundances were compared after
grouping the transects into four different sets, representing
different coastal regions. The most notable differences between
years were obtained for the butterflyfishes (Chaetodontidae)
(Table 7); although these were small at 3 m depth, they were
marked at 10 m depth, with lower abundances being recorded
in 2002/2003 than in 1996. By contrast species richness was
greater in 2002 than in 1996, at 3 m depth in all regions, and at
10 m depth in all regions except Tiran Islands.
To compare the hard coral cover values found during the
present study with those from earlier studies undertaken by
different authors (Loya and Slobodkin, 1971; Loya, 1972;
Benayahu and Loya, 1977; Spalding, 1992; Kotb, 1996; Kotb
et al., 1996; Medio, 1996; Ormond, 1996; Hassan et al., 2002;
Lawrence and Hollingworth, 2002), published mean hard coral
cover values obtained within each of three depth ranges
(1–7 m, 7–12 m and 12–19 m.) were plotted against time (the
Copyright # 2008 John Wiley & Sons, Ltd.
dates of the studies concerned), (Figure 6). Marked trends of
decreasing coral cover from 1971 to 2002 were apparent with
the two shallower zones, 1–7 m and 7–12 m, with that at 1–7 m
being statistically significant (Spearman rank order
correlation, rs ¼ 0:900; P ¼ 0:037), whereas at 12–19 m no
trend was apparent.
DISCUSSION
Coral assemblages
In the present survey mean coral cover across all stations was
found to decline with depth, a pattern confirming the decline in
coral cover with depth described from previous studies
undertaken in the Red Sea (Loya and Slobodkin, 1971;
Loya, 1972; Kotb, 1996; Kotb et al., 1996; Medio, 1996; De
Vantier, 2000; Tilot et al., 2000). However, cover varied
between sites, with those with either shallow slopes (e.g. Marsa
Bareika Mooring and South, Sheikh Coast), or very steep ones
(e.g. Aqaba Beach) having less coral. The lower cover on reefs
with shallow slopes may be attributed to the greater amounts
of sand accumulated on the reefs at these semi-enclosed sites
(Kotb et al., 2001), whereas that on near vertical slopes is
probably due to reduced illumination and lack of suitable
surfaces for larval settlement and colony growth (Sheppard,
1982; Kotb, 1996).
No general relationship between level of tourist activity and
coral cover was evident, with, for example, no segregation
between sites heavily used by tourists and those lightly used by
tourists being evident in an MDS plot. This finding appears
contradictory given that some popular sites (e.g. Ras Um Sidd)
Aquatic Conserv: Mar. Freshw. Ecosyst. 18: 1109–1126 (2008)
DOI: 10.1002/aqc
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V. TILOT ET AL.
Table 6. Comparison of percentage substratum cover by hard and soft
corals and by principal genera of corals between 1996 (Ormond, 1996)
and 2002 (this study) at each of the two stations surveyed in both years
Depth (m)
1
3
8
7
15
16
Year
1996
2002
1996
2002
1996
2002
Jackson Reef
Hard corals
Soft corals
Acropora spp.
Stylophora spp.
Porites spp.
Millepora spp.
Lithophyton spp.
Xeniidae
Dendronephthya spp.
Sinularia spp.
63.7
5.1
23.2
0
9.3
6.0
4.9
0.0
0
0
36.5
14.8
13.0
0
10.3
7.1
8.0
3.7
0
0
27.9
29.7
5.9
2.9
3.3
7.4
1.3
14.7
7.4
0
18.2
33.0
4.6
1.8
6.5
1.7
12.5
16.0
3.8
0
16.6
41.4
4.7
1.9
2.6
5.4
0.0
34.9
0
5.9
11.8
38.3
1.1
1.9
1.5
1.7
9.0
24.1
0
1.5
Aqaba Beach
Hard corals
Soft corals
Acropora spp.
Stylophora spp.
Porites spp.
Millepora spp.
Lithophyton spp.
Xeniidae
52.0
0.7
31.7
4.2
0
0
6.1
0
15.7
3.2
7.5
3.9
0
0
3.6
0
31.3
2.0
6.2
0
8.5
6.5
4.3
1.2
7.0
2.5
0.2
0
1.3
0.6
4.1
0.4
27.4
5.5
8.7
0
0
8.2
0
5.3
2.2
9.7
0.1
0
0
0.0
0
9.2
Table 7. Mean species richness and overall abundance of
butterflyfishes (Chaetodontidae) per 500 m2 in 1996 (Ormond, 1996)
and in 2002, at each depth in each of four sectors within which data
were pooled
Sector
Species richness
3m
Abundance
10 m
3m
10 m
1996 2002 1996 2002 1996 2002 1996 2002
Dahab
Tiran
Sharm El Sheikh
Ras Mohammed
5.0
5.1
6.4
6.8
9.0
8.0
9.5
8.0
4.8
6.8
4.0
7.4
6.0
6.0
7.5
12.0
19.1
17.6
19.2
21.2
27.5
16.0
22.3
19.0
11.9
12.7
17.1
14.4
6.8
10.5
14.1
10.6
are believed to have experienced a significant localized decline
in coral cover (Leujak, 2006). However, it is suspected that the
reef sites to which most visitors were initially attracted, and
which remain most popular, were among those where coral
cover was originally greater; certainly some of the stations with
relatively little coral, such as Aqaba Beach and Marsa Bareika
South, attract relatively few visitors. Thus, even assuming
coral cover has declined at some of these popular sites, mean
cover at the most used sites may still be no lower than that at
less used sites. In addition other impacts such as predation by
Copyright # 2008 John Wiley & Sons, Ltd.
Figure 6. Mean percentage hard coral cover reported from various
locations along the Gulf of Aqaba from 1971 to 2002 at three depth
ranges: (a) reef edge to 7 m; (b) 7 to 12 m; (c) 12 to 19 m. Data are from
Loya and Slobodkin, 1971 (m); Loya, 1972 (&); Benayahu and Loya,
1977 (*); Spalding, 1992 (^); Kotb et al., 1996 ({); Kotb, 1996 ({);
Ormond, 1996 ({); Medio, 1996 ({); Hassan et al., 2002 (&);
Lawrence and Hollingworth, 2002 (&); Tilot, 2003 (&); Smith and
McMellor, 2006 (*).
crown-of-thorns starfish may have had a larger influence on
coral abundance, so tending to obscure any weaker
correlation.
Over all transects 36 coral genera were identified. This is
lower than numbers recorded from the same region by others,
e.g. 57 (Kotb, 1996), 45 (Medio, 1996), 47 (Pilcher and Abu
Zaid, 2000), however, these other studies involved surveys over
larger areas and to greater depths. In addition video sampling,
due to limited image resolution, is poor at discriminating taxa
that are cryptic or closely resemble others. Video sampling can
discriminate differences in substrate cover of major benthic
categories or taxa, but where an accurate assessment of species
or genus diversity is required, it is probably best to make use of
a different method, such as a structured open search (Leujak
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DOI: 10.1002/aqc
MONITORING OF SOUTH SINAI CORAL REEFS
and Ormond, in press b), alongside video-sampling. Another
difference between the data generated by the method used in
this study, and those obtained in some other studies is that the
data described here show the mean number of genera per
transect declining with depth, whereas normally highest hard
coral diversity is thought to occur about a quarter of the way
down the total hermatypic depth range (Sheppard, 1982), with
for example the maximum numbers of genera being found at
10 to 15 m in Southern Sinai (Kotb et al., 1996), and 6 to 20 m
on the Saudi Arabian Red Sea coast (De Vantier, 2000). The
difference between the trend found here and that reported by
other studies is a consequence of the restricted sampling area
of the individual transects. Even though on the upper parts of
reefs coral diversity across large areas does indeed decline with
depth, most of these taxa are sparsely distributed, and, since
most corals become less abundant with depth, the number of
genera or species present within smaller sampling areas, such
as individual transects, actually decreases with depth.
Analysis of the coral data, both by growth-form and by
genera, confirms that both depth and degree of exposure to
wave action are major factors influencing the coral assemblage.
In particular the MDS plot shows a clear segregation of
transects according to depth. This well documented effect is
presumed to be principally a consequence of reduction in light
intensity with depth, which favours foliose and tabular lifeforms (Sheppard and Sheppard, 1991). Wave exposure has
also long been recognized as a major factor influencing coral
assemblage composition (Rosen, 1971; Sheppard, 1982; Sebens
and Done, 1992), with, as observed here, shallow sections of
exposed stations generally being dominated by branching
Acropora spp., and those of sheltered stations by massive
Porites spp. At the same time, as confirmed by the present
data, relative abundances of branching corals tends to decrease
with depth, whereas that of massive corals increases (Loya and
Slobodkin, 1971; Kotb, 1996; Kotb et al., 1996). These findings
support the view that branching corals are better adapted than
massive corals to high levels of wave action and light intensity,
both of which are greater along the reef edge than at depth
(Head, 1987; Sebens and Done, 1992). The present study also
shows an increase in abundance of soft corals with depth,
especially of xeniids, as also reported from within the region by
Schuhmacher (1975), Tilot et al. (2000) and Kotb et al. (2001).
At the same time highest soft coral covers at all depths were
recorded at Jackson Reef, a station characterized by exposure
to strong currents, conditions which are known to favour soft
corals, since they rely more heavily on plankton for food than
do hard corals (Fabricius and Alderslade, 2001).
Fish assemblages
Sixty-five fish species were recorded during the survey; by
contrast Pilcher and Abu Zaid (2000) recorded 261 species in
Copyright # 2008 John Wiley & Sons, Ltd.
1121
the southern Egyptian Red Sea, with Pomacentridae and
Labridae being the most abundant families, and Khalaf and
Kochzius (2002) observed 198 species in an investigation on
the Jordanian coast, with Pomacentridae being most
abundant. However, in the present study only a portion of
the fish fauna present were recorded, since only selected
families were counted, with, in particular, several of the most
speciose families, notably Pomacentridae and Labridae, being
excluded. This approach, however, enables sampling effort to
be focused on families thought to be of greater ecological and
fisheries significance, thus generating in relation to those
families greater statistical power (Ashworth and Ormond,
2005).
Despite this restriction a number of general trends were
evident, total abundance, for example, being significantly
higher on shallow transects than on deeper ones. This greater
abundance at the reef edge has been widely reported for Red
Sea reefs, including from Sudan (Edwards and Rosewell, 1981)
and Saudi Arabia (Roberts and Ormond, 1987), although on
the Jordanian coast fish abundance has been found to be
higher at 12 m than at 6 m (Khalaf and Kochzius, 2002), a
difference probably related to the atypical structure of the
fringing reefs there. Analysis also demonstrates changes in the
fish assemblage with depth, MDS clearly separating
assemblages at 3 and 10 m. In particular shallower transects
had higher abundances of herbivores such as A. nigrofuscus, A.
sohal and Zebrasoma xanthurum, and of corallivores such as
Chaetodon austriacus and C. trifascialis, this pattern
presumably being linked to the greater algal and coral cover
in shallow water characteristic of Red Sea reefs (Sheppard
et al., 1992).
Neither overall fish abundance nor species richness were
found to be correlated with hard coral cover, even though hard
corals provide food or shelter for fish and might therefore be
expected to have an influence on fish assemblages (Sale, 1991).
However, while a series of studies have found positive
correlations between fish species richness and abundance and
hard coral cover (Carpenter, 1981; Bell and Galzin, 1984; Syms
and Jones, 2000; Gratwicke and Speight, 2005a, b; Brokovich
et al., 2006), other studies have detected no such correlation
(Sale and Douglas, 1984; Roberts and Ormond, 1987; Öhman,
1998), findings that have been attributed to studies using
different spatial scales (Friedlander and Parrish, 1998; Pittman
et al., 2004) or fish assemblages in some regions being
structured by other processes, such as competition or
recruitment (Sale, 1991).
Correlations between fish abundance and diversity and live
coral cover may also occur within particular families, and in
particular have been widely reported for butterflyfish species
feeding exclusively on corals (Bell and Galzin, 1984; BouchonNavaro and Bouchon, 1989; Öhman et al., 1998; Findley and
Findley, 2001; Khalaf and Kochzius, 2002), even though the
Aquatic Conserv: Mar. Freshw. Ecosyst. 18: 1109–1126 (2008)
DOI: 10.1002/aqc
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V. TILOT ET AL.
present study, as well as those by Roberts and Ormond (1987)
in the Saudi Arabian Red Sea, and by Khalaf and Crosby
(2005) in the Jordanian Red Sea, found only weak
correlations. An explanation may be that in the Red Sea
butterflyfish abundance may level off or even decline at high
coral covers, as a result of reduced habitat diversity (Ormond,
unpublished data).
While on the MDS plot of fish data there is at each depth a
broad overlap in the points representing most stations, this
analysis and the corresponding ANOSIM demonstrated a
significant difference between two particular stations, Aqaba
Beach and Jackson Reef, and the remaining ones. These
differences seem likely related to the atypical structures and
locations of these two sites, Aqaba Beach being a near vertical
wall at Ras Mohammed adjacent to very deep water, and
Jackson Reef one of the tower-like reefs exposed to very strong
currents in the Straits of Tiran.
However, the most marked difference in fish assemblage was
that between the Islands Dahab station, the only one subject to
fishing, and all other stations. Overall fish abundance at 3 m
was lower than at the non-fished stations, as was the
abundance of key commercial families at both 3 and 10 m
depth. Fishing is the most likely cause of these differences since
higher densities of targeted species in non-fishing zones have
now been widely recorded, including from within the Red Sea
(Roberts and Polunin, 1992; Galal et al., 2002). Further, the
abundance of Acanthuridae was higher at the fished Islands
Dahab station than at the other sites, and such greater
abundances of Acanthuridae within fished areas has also been
described from elsewhere in the region (Ashworth and
Ormond, 2005) and has been attributed to the removal
through fishing of their natural predators.
Comparisons with other surveys
Mean hard coral cover across all nine stations was 29.8% at
3 m, 18.3% at 7 m and 11.8% at 16 m. These values are lower
than those which, in the experience of the present authors,
many nonspecialist divers and at least some marine scientists
assume to be typical of healthy reefs in the northern Red Sea
reefs. On the one hand it is now widely appreciated that
subjective estimates of coral cover (i.e. those made by eye,
without quantitative measurement) commonly over-estimate
coral cover. On the other hand, given the exponential increase
in coastal tourism to South Sinai and the increasing range of
impacts to which reefs there have become subject, it would not
be surprising if coral cover was being affected, at least in some
areas. However, despite the numbers of studies completed and
the amounts of data collected, it remains difficult to determine
whether or not a general decline in coral cover is evident across
South Sinai reefs.
Copyright # 2008 John Wiley & Sons, Ltd.
The mean values of coral cover observed in the present study
are lower than those found in the 1996 pilot survey when, over
12 sites, mean hard coral cover determined by the photoquadrat method was 45% at 1 m depth, 25% at 8 m and 20%
at 15 m (Ormond, 1996). Unfortunately, given the difference in
sites and depths, statistical comparison of these two datasets is
of uncertain value. However, as described above, the locations
of two of the stations surveyed in the present study, Aqaba
Beach and Jackson Reef, did coincide precisely with those
surveyed in 1996, and at these sites it appears that between
1996 and 2002 hard coral cover decreased by between 5% and
25%. The decrease appears most pronounced at shallow
depths, and mostly due to a decrease in cover of Acropora spp.,
of 24% at Aqaba Beach and of 10% at Jackson Reef. At the
same time these same sites appear to have experienced an
increase in cover of soft corals, especially xeniids. Both coral
and fish abundance analyses have suggested that these two
sites are atypical, and it has been suggested that this is likely
due to their locations close to deep water and exposure to wave
action, though in principle such a distinction could also be a
consequence of something affecting the reef community only at
these two particular sites. In fact a genuine change in coral
cover at these site seems plausible, since they are on two of the
main reefs that were affected by an outbreak between 1996 and
1999 of the coral-eating crown-of-thorns starfish (Acanthaster
planci) (Salem, 1999). Crown-of-thorns are known to favour
corals of the genus Acropora as food (De’ath and Moran,
1998), which would explain the decline in Acropora spp. The
increase in cover of soft corals of the family Xeniidae at these
same sites probably occurred as a result of their occupying
substrate space made available through loss of hard corals,
since xeniids are known to be an opportunistic family, able to
quickly colonise vacant space as a result of a high fecundity
and rapid asexual reproduction (Benayahu and Loya, 1984,
1985).
The comparison made of the present data with those
obtained from other quantitative studies in the Gulf of
Aqaba is also problematic, since these studies focused on
different areas and used a bewildering array of different
methods (Loya and Slobodkin, 1971; Loya, 1972; Spalding,
1992; Kotb, 1996; Kotb et al., 1996; Hassan et al., 2002;
Lawrence and Hollingworth, 2002), making the coral cover
values obtained more variable, and hence any underlying trend
in coral cover more difficult to detect. For the deepest depth
range within which data were compared, 12–19 m, no trend
was apparent. For the two shallower depth ranges (1–7 m and
7–12 m), however, the regressions suggest trends of decreasing
coral cover between 1971 and 2006, with that at 1–7 m being
statistically significant. Furthermore, whereas at Ras Um Sidd
the present study recorded 37.5% hard coral cover at 3 m
depth and 18.1% at 7 m depth at Ras Um Sidd, a more recent
study by Smith and McMellor (2006) recorded only 28.6%
Aquatic Conserv: Mar. Freshw. Ecosyst. 18: 1109–1126 (2008)
DOI: 10.1002/aqc
MONITORING OF SOUTH SINAI CORAL REEFS
hard coral cover at 2–6 m depth and 18.4% at 9–12 m at this
same site, suggesting that a decline might be continuing. A
combination of no change in coral cover over time at 12–19 m,
and trends of declining cover at 1–7 and 7–12 m is not
implausible, since the principal factors affecting the region’s
reefs (coral damage by divers and snorkellers, artisanal fishing
and predation by crown-of-thorns starfish) tend principally to
affect the shallower parts of reefs.
Two activities are known to have caused significant coral
mortality at some sites within the South Sinai region during
the time frame of the pilot and present surveys. Coral damage
and death from trampling or physical impact by visitors reef
walking, snorkelling or diving has been described on reefs
sites both north and south of Sharm El Sheikh, and has
been reported as causing a reduction in coral cover in reef
areas around Ras Mohammed and Ras Um Sidd (Hawkins
and Roberts, 1992b, 1993; Leujak, 2006). Of the stations
used in the present study one, that at Ras Um Sidd, falls
within a reef shown to be affected by visitors (Hawkins and
Roberts, 1992b, 1993; Leujak and Ormond, in press a), while
four others (Aqaba Reef, Sheikh Coast, and the two
Dahab stations) are on reefs where reef walking and
snorkelling by visitors is common. Reef trampling is
known to particularly affect branching corals (Hawkins and
Roberts, 1992b, 1993; Medio, 1996; Leujak, 2006) and so
could also be the cause of a reduction in relative abundance of
Acropora spp.
Extensive coral mortality has also occurred within the
region over the time period concerned as a result of
an outbreak of crown-of-thorns starfish, A. planci, which
affected reefs between Ras Mohammed and the Tiran Straits
during 1998–2001 (Salem, 1999; Ayman Mabrouk, personal
communication), and reefs around Dahab during 2001/2002
(Mabrouk, unpublished data; Penberthy, personal communication). During these outbreaks 72 000 starfish were collected
by National Park staff and volunteers from reefs between Ras
Mohammed and the Tiran Straits, and 40 000 from reefs
around Dahab. All the stations used in the present study were
on reefs known to have been affected by crown-of-thorns
starfish during the period concerned, save for Ras Umm Sidd
and Sheikh Coast. As mentioned above, predation by crownof-thorns starfish, like damage by snorkellers and divers, tends
to lead to a reduction in the proportional abundance of
Acropra spp. (De’ath and Moran, 1998).
Concluding remarks
The present study has characterized the abundances of hard
and soft coral genera and growth forms and significant reef fish
families on a series of South Sinai reefs, using a method that is
precise enough to distinguish between depths and between
some subsets of reefs and others. However, because of the
Copyright # 2008 John Wiley & Sons, Ltd.
1123
variety of methods used in previous studies and the range of
locations investigated, it has not been possible to make an
adequate statistical comparison between the data obtained
here and that from previous work. Thus, the data do not
provide conclusive evidence for any overall change in coral
cover over recent decades; but the results do not exclude the
possibility that there has within this time been a modest overall
decline in coral cover across the South Sinai region. During
this period a proportion of reefs are known to have been
affected by either human aquatic activities and/or large
numbers of coral-eating crown-of-thorns starfish. But
whether a monitoring programme based on even a sizeable
set of stations detects an overall change in coral cover will
depend not only on the precision of the method used, but also
on how many affected reefs are by chance included when the
location of monitoring stations is determined.
The present method was selected for use because, of six
methods compared in a preliminary study (Leujak, 2006;
Leujak and Ormond, in press b), it proved to be the most costeffective in terms of precision of estimate gained per unit time,
a conclusion in agreement with other recent assessments of reef
monitoring protocols (Hill and Wilkinson, 2004). Even then,
because of the high patchiness of reef communities, and hence
the limited statistical power of even the most effective survey
protocols, establishing any broad trend in coral cover with
statistical confidence has proved difficult. To determine with
confidence whether or not there is any ongoing broadscale
change in coral (or reef fish) abundance, it will be necessary to
undertake within the foreseeable future a repeat survey
employing precisely the same stations and same methods as
those described here. Given the past impact by visitors or
crown-of-thorns starfish on at least some of the present sites,
such further monitoring is highly desirable. Where, in the light
of technological advance, such as the availability of higher
resolution digital video and still camera, it seems desirable to
modify the protocol, it is nevertheless key that the old one is
run along side the new in order both to establish a conversion
rate between the two methods, and to ensure that new data can
be compared with the old data.
ACKNOWLEDGEMENTS
The work was supported through grants and assistance-inkind by the European Commission, the Egyptian
Environmental Affairs Agency, the British Council and the
‘Konsul Karl and Dr. Gabriele Sandman Stiftung’.
We thank the Egyptian Environmental Affairs Agency for
facilitating the work, and express our gratitude to their senior
staff, including Dr Alain Jeudy de Grissac, Dr Moustafa
Fouda, Dr Mohammed Salem, Essam Saadallah and Medhat
Aquatic Conserv: Mar. Freshw. Ecosyst. 18: 1109–1126 (2008)
DOI: 10.1002/aqc
1124
V. TILOT ET AL.
Rabie. We also thank Yasser Awadalla, Belal Saleh, Yasser
Said, Ahmed Ibrahim, Tarek Haroun and Ahmed Hamdi for
help in the field, and the Anemone Dive Centre and Sinai
Divers for loan of scuba tanks and use of boats. Finally we
thank the editor and two referees for numerous constructive
comments.
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