1. pets
2. aquariums

ABUNDANCE AND DIVERSITY OF CORAL REEF FISH LARVAE AT HURGHADA,
EGYPTIAN RED SEA
Mohamed Abu El-Regal (*1) A. I. Ahmed (*2); S.G. El-Etreby(*2), M. ElKomi(*1) ; and
Michael Elliott (*3)
*1 National Institute of Oceanography & Fisheries, Egypt
*2 Suez Canal University, Faculty of science, Marine Science Dept. Ismailia, Egypt
*3 Institute of Estuarine & Coastal Studies, University of Hull, Hull, HU6 7RX, UK.
Key words: Abundance, diversity, fish larvae, Hurghada, Red Sea, Egypt
ABSTRACT
The larvae of coral reef fishes have been studied in Hurghada, Egyptian Red
Sea at exposed and sheltered inshore and offshore. Ichthyoplankton samples were
taken by plankton net on a monthly basis from January to December 2005. The total
abundance of fish larvae at all sites was 1993/1000m3. There were significant
differences in larval abundance between sites but not between months. The inshore
sheltered site (H3) had a significantly higher abundance of all sites, whereas the inshore
exposed Abu Sadaf site had the lowest abundance. The most abundant 10 taxa,
Atherinomorus lacunosus (Atherinidae), Spratelloides delicatulus (Clupeidae), Gerres
oyena (Gerreidae), Hypoatherina temmincki (Atherinidae), Petroscirtes mitratus
(Blennidae), Vinciguerria mabahiss (Phosichthyidae), Enneapterygius sp. (Triptrygiidae),
Mulloides flavolineatus (Mullidae), Benthosema pterotum (Myctophidae) and Gobiidae,
formed about 82.5% of all larvae collected. The most dominant species was
Atherinomorus lacunosus contributing 19% of all taxa with a total abundance of 113
larvae/1000m3 Larvae of families Siganidae and Soleidae were the least abundant both
0.23 larvae/1000m3
INTRODUCTION
Fish eggs and larvae represent the meroplanktonic stages of fishes that can be
collected by planktonic gears and are found mainly in the upper 200 meters of the water
column. They can be used to determine the geographical distribution of fishes (Leis,
1986, Leis & McCormick, 2002) because they have a broader range than their reef
1
sedentary demersal adult stages (Sale, 1980 & 2002). They also serve to estimate the
spawning stock, the spawning seasons and spawning grounds of the commercial fishes.
Determining the abundance of eggs and larvae in an area is usually less expensive to do
than sampling the adults because it is possible to sample several species over broad
areas with simple plankton net. Besides, the plankton samples contain not only the fish
larvae but also part of their potential zooplanktonic prey and predator (Smith &
Richardson, 1977).
Although the adult reef fishes of the tropical Indo-Pacific in general and the Red
Sea in particular are well studied (Botros, 1971; Randall, 1983; Debelius, 1998), very
little is known about their larval stages. There have been no previous studies on the
larvae of coral reef fishes in the Red Sea. Literature describing the larval stages of coral
reef fishes is also sparse or even lacking due to the identification difficulty. (Leis &
Rennis, 1983; Houde et al., 1986). Problems associated with the larval work can be
summarized in taxonomy and sampling. Difficulties in identification stem from the fact
that the pelagic stages of reef fishes are totally morphologically different from the adults.
So, fish larvae are difficult to be identified that more work on fish larvae has not been
done. The understanding of the biology of fishes can not be adequate unless the natural
history and ecology of the larvae are well studied (Leis & Rennis, 1983). So, the present
study aims to identify the larval stages of coral reef fishes and to investigate their
diversity and abundance at Hurghada, Egyptian Red Sea.
MATERIAL AND METHODS
Sampling and preservation
The environmental parameters temperature and salinity were measured
seasonally using a Hydro-Lab meter, Surveyor (4) Ichthyoplankton samples were
taken monthly from January to December 2005 using a 50 cm mouth diameter and
0.5 mm mesh size plankton net provided with a flowmeter to calculate the volume of
water filtered. Nets were towed horizontally at 1 m depth near the reef edge for about
10 minutes with a towing speed of 1.5 knots. Samples were taken in the early
morning just before sunrise and preserved immediately in buffered 5% formalin
seawater. Three replicates were taken; the mean abundance and mean volume of
water were calculated. The volume of water filtered ranged from 64 m3 in April to 133
2
m3 at in January (Table 1). Densities of fish larvae were standardised to 1000 m3 of
water.
Laboratory procedures
The samples were sorted and examined under an Olympus SZX7
stereomicroscope and then identified to the highest possible taxonomic separation.
All larvae were measured to the nearest 0.1 mm before final preservation in 70%
ethanol. They were identified using the identification guides of Leis & Rennis, (1983),
Abu El-Regal (1999), and classified according to Leis and Carson-Ewart (2002).
Data analysis
The univariate statistics were done in SPSS v.15.0, using ANOVA to
determine differences in the numbers of individuals and number of species between
months and sites. All data were tested for homogeneity of variance. Where the
samples were not homogeneous, data were either logarithmically or square root
transformed or the non-parametric Kruskal-Wallis test was used (Zar, 1996; Dytham,
2003). The cluster analysis and diversity indices (species richness, the evenness and
Shannon-Wiener), were calculated using PRIMER v 5 after standardization and
square root transformation.
RESULTS
Study area
The study area at the northern part of Hurghada, on the Egyptian Red Sea was
divided into inshore and offshore sites (Fig. 1). The inshore site is located directly in
front of the Marine Biological Station (Table 2). It is a small area that extends to
about 150 m seaward and ended with a lagoon of 5 m deep. The lagoon has sandy
bottoms with algal mats and seagrass beds and is inhabited by many species of
corals and fishes. The lagoon is followed by a reef flat with many coral species. The
open sea adjacent to the reef flat descends to 12m deep. Abu Sadaf is located about
1000 m away from the shore with a depth of from 1-2m. It is formed of many patched
of corals that enclose some sandy areas where the sampling process was carried
out. Three sub-sites, sheltered side (H3), exposed side of the reef flat (X3) and Abu
Sadaf (AS) were sampled. The second area, Giftun Islands, is a very popular dive
site located about 15 km away from the Hurghada coast and includes extensive and
3
diverse coral cover and fishes. Small Giftun (SG), Sabina 1 reef wall (X1, H1) and
Sabina 2 reef wall (X2, H2), were sampled (Table 2).
Hydrographical conditions
Low variability in environmental conditions was observed among sites and
seasons. The annual mean surface water temperature was 24.9°C offshore and
25.2°C inshore with the maximum during summer and early autumn (July-September)
and the minimum during winter (January-March) The seasonal and regional
distribution patterns of salinity showed very slight variations with a mean annual
salinity of 39.8 offshore and 39.9 inshore (Table 3).
Abundance of fish larvae
A total of 1799 larvae were collected from all sites throughout a year of sampling.
The total abundance was 1993 larvae/1000m3. The abundance of fish larvae was high in
late spring and summer (May-August) with the highest value in May (135
individuals/1000m3)
whereas
the
lowest
abundance
was
in
January
(11
3
individuals/1000m ) (Fig.2). The analysis of ANOVA indicated a significant difference
between months (P<0.05). The sheltered inshore (H3) had the highest number of larvae
with an average annual abundance of 253 individuals/1000m3. The lowest abundance
was recorded in the inshore site AS with average abundance of 35 /1000m3 (Fig. 3).
ANOVA analysis showed that H3 and SG were significantly different from the other sites
(P<0.05).
Larval diversity
Throughout the whole period of study, larvae of 63 taxa belonging to 16 orders
and 44 families of fish were identified. Most larvae could be identified to different
taxonomic levels; 27 taxa could be identified the species level, 17 taxa to genus and 19
taxa as family. Approximately, 2.5% of the collected larvae could not be identified.
Larvae of 25 taxa forming approximately 40% of all taxa collected were taken in July
recording the highest number of taxa followed by May and June (21), and August (18).
The lowest number of taxa was recorded in November (3) (Fig. 2).
The sheltered offshore site, H3 and the offshore sites Small Giftun had the highest
number of species where 31 and 28 taxa respectively followed by X2 (23). The sheltered
offshore sites H1 (5 taxa) and H2 (4 taxa) were very poor in diversity (Fig. 4). Regarding
4
the number of taxa, there was a significant difference among sites (F=12.8 P< 0.01) and
months (χ2 = 33.5 P<0.05).
The most diverse order was the Perciformes that contained 22 families and 34
taxa. The most abundant 10 taxa identified, Atherinomorus lacunosus (Atherinidae),
Spratelloides
delicatulus
(Clupeidae),
Gerres
oyena
(Gerreidae),
Hypoatherina
temmincki (Atherinidae), Petroscirtes mitratus (Blennidae), Vinciguerria mabahiss
(Phosichthyidae), Enneapterygius sp. (Triptrygiidae), Mulloides flavolineatus (Mullidae),
Benthosema pterotum (Myctophidae) and Gobiidae, formed about 82.5% of all larvae.
Larvae of Atherinomorus lacunosus were the most abundant contributing about 19% of
all taxa with a total abundance of 113 larvae/1000m3 followed by Spratelloides
delicatulus and Gerres oyena that constituted 12.1% and 11.9% respectively (Fig.5).
Larvae of families Siganidae and Soleidae were the least abundant with 0.23
larvae/1000m3 each (Table 4).
Species richness reached its maximum value in Small Giftun (3.7), followed by
X2 (3.5) and H3 (2.7). It varied significantly between months and sites. The evenness
index was significantly different between months (χ2 = 28 P<0.05) but was not between
sites (F= 1.78 P>0.05). The species diversity was highly significant between months and
sites (Fig. 6, Fig. 7). In general there was significant difference in the species richness at
inshore and offshore sites (F= 2.594, P<0.05) and some taxa such as Scaridae,
Labridae, Acanthuridae and Priacanthidae were restricted to either inshore or offshore
sites. The larvae of 24 taxa were restricted to the offshore sites and 15 taxa were
restricted to the inshore areas. At the inshore sites, larvae were more abundant and
diverse on the sheltered side than the exposed side. In contrast, the offshore sites had
larger numbers of larvae and species on the exposed sides.
DISCUSSION
Fishes of the Red Sea, have been extensively studied (e.g. Gohar, 1948; Gohar and
Latif, 1959; Al-Kholy, 1964; Botros, 1971; Randall, 1983; Ormond and Edwards, 1987;
Ahmed, 1992). A comprehensive checklist of Red Sea species was published by Goren
& Dor (1994). However, ichthyoplankton has been studied very little in the Red Sea
(Nellen, 1973; Abu El-Regal, 1999; Faroukh, 2001). The lack of literature on larval
5
systematics in the Red Sea made the ichthyoplankton identification task even more
difficult than had been anticipated. There is a critical need for careful taxonomic studies
on the larvae to aid future research in the Red Sea. Knowledge of the ichthyoplankton
can be useful in estimating the size of a spawning stock and in determining the
spawning seasons and spawning grounds of the commercial fishes, and is urgently
needed as a tool to manage the Red Sea fisheries and its coral reefs.
Despite differences in sampling methods, the present study confirmed the highest
abundance of fish larvae from May to August as reported for the northern Red Sea (ElSherbiny, 1997; Abu El-Regal, 1999; Faroukh, 2001). The larval abundances and
predominant taxa were similar to that in Sharm El-Sheikh (Abu El-Regal, 1999). More
fish families (44) were collected during the present study than those from Sharm ElSheikh (32) and Aqaba (25). Larvae of some families such as Pomacanthidae, Scaridae,
Microdesmidae, Gerreidae and Engraulidae were collected from Hurghada but not from
Sharm El-Sheikh and Aqaba (Abu El-Regal, 1999; Faroukh, 2001). Of the most
abundant families in Aqaba; Clupeidae, Pomacentridae, Apogonidae and Gobiidae
(Faroukh, 2001), only Clupeidae was dominant in the present work. Similarity in species
composition of fish larvae between Sharm El-Sheikh and Hurghada was because of the
similar environmental conditions and differences may be due the different sampling
gears.
In the current work, most larval fish taxa collected are reported as adults in the
Red Sea. Most notably, larvae of some families of reef fishes are missing in the area of
study although they occur in the area as adults. Similarly, many studies reported adults
of fish families but did not find their larvae (Miller, 1974, 1979; Watson & Leis, 1974;
Young et al., 1986) in Great Barrier Reef in Australia. Leis (1994) considered it possible
that pelagic larvae of many coral reef fishes disperse from their natal reef. Hence the
inshore larval assemblages may not be fully representative of the adult fish assemblage.
Many of the missing reef fish larvae inshore were found 5-12km offshore in Hawaiian
waters (Leis & Miller, 1976). Thus, the propagules originating from a fish population on a
given reef are not necessarily retained near that reef; hence the rarity or absence of
larvae of some of the coral reef fishes from the area.
Chaetodontidae, Scaridae and Lutjanidae have a very short planktonic life
(Lowe-McConnell, 1979). Jones et al., (2005) found that the larvae of pomacentrid
6
Amphiprion polymnus has a larval duration of 9-12 days that is shorter than that of other
coral reef fishes. They expected that this species have a very short dispersal from the
natal reef. On the hand, some larval stages have very long larval duration. In the present
work, leptocephali were very rare in the collection and could not reflect the eel’s
assemblages in the area. The vast majority of leptocephali simply avoid the net due to
their large size and excellent swimming ability both forward and backward that makes
them well adapted to avoid small plankton nets. Their large eyes enable them to avoid
nets at the day light. Leptocephali can be taken in large number only at night. The best
plankton net for collecting leptocephali appears to be the Isaacs Kidd Midwater Trawl
(Miller et al., 2006).
The larval fish assemblages in coastal tropical waters are a result of spawning
activities of reef fish, and open water fish that is dominated by mesopelagic fishes
(Ahlstrom, 1971; 1972; Leis & Goldman, 1987). Larvae of 35 coral reef fish families were
collected in the present study, of which, 21 families were taken from inshore and 28
were taken from offshore. Surprisingly, larval mesopelagic fishes are abundant near the
coral reef and this is in agreement with the findings of Leis (1991a). He concluded that
mesopelagic larvae may be brought to the reef by water currents.
The distribution of fish larvae can be influenced by the environmental conditions
(Hernández-Miranda et al, 2003). In the present study, there were no significant
differences in water salinity and temperatures between different sites, but between
seasons. Hence temperature may influence the temporal but not the spatial distribution
of fish larvae in the Red Sea. The highest catch and taxon richness of fish larvae in
summer may be due to high temperatures in the area of study during summer. The
abundance and location of larvae may be strongly related to the habitat type and/or
spawning ground of the adult. These correspond to areas that favour the subsequent
coupling between spawned cohorts and the presence of food (Cushing, 1990). IndoPacific coral reefs, including the Red Sea, have a complex topography, hydrography and
biota. The structural complexity of coral reefs provides a variety of habitats, most of
which support fish larvae (Leis, 1991b). However, in the present study, the topography
and complexity of the reef differed greatly from site to another.
At the inshore sites, larvae were more abundant and diverse on the sheltered
side than the exposed side. In contrast, the offshore sites had larger numbers of larvae
7
and species on the exposed sides. Most larvae collected from the offshore exposed sites
hatched from pelagic spawners whereas the majority of fish larvae in the offshore
sheltered sites hatched from demersal eggs. This is consistent with results of other
studies where larval fish assemblages inshore were dominated by larvae from demersal
spawners (Leis 1982; Smith et al., 1987; Suthers & Frank, 1991; Leis & McCormic,
2002; Paris and Cowen, 2004).
Most of the larval fish taxa collected during the current study are commercially
important such as Mullidae, Lutjanidae, Scaridae, Carangidae, Sphyraenidae, Gerreidae
and Serranidae which are the major constituents of the fishery in the Red Sea in general
and Hurghada in particular. Other larvae were belonging to ornamental fishes that can
be used in aquarium trade and as game fishes. The culture of marine tropical fish
conserves natural reef resources by offering alternatives to wild capture and develops a
new source of organisms for the aquarium trade. Although many of the fresh water
tropical species sold to the public are now cultured, more than 90% of all marine tropical
ornamental organisms continued to be collected from the wild.
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Table (1) Mean water volume and mean larval abundance of fish larvae at different
months and site
SD= standard deviation
11
Water volume
Abundance
Water volume
H1
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Mean
77.7
76.7
74.7
64.7
78.3
72.3
71.0
72.2
72.7
71.3
71.4
65.7
SD
12.7
13.8
10.1
3.1
11.7
9.7
12.1
18.4
4.7
1.5
16.5
12.7
Mean SD
0
0
4
8
0
0
4
8
0
0
0
0
0
0
0
0
1
2
1
1
4
5
0
0
Water volume
Abundance
Mean
133.4
110.9
103.7
115.0
105.2
114.7
121.0
124.3
118.8
119.1
123.3
119.1
Mean
78.7
79.1
77.8
71.3
73.5
82.1
69.9
66.7
77.8
76.9
79.2
76.5
Water volume
Mean SD
0
0
0
0
1
1
3
3
0
0
0
0
9
7
11
14
1
2
0
0
0
0
1
1
Mean
117.3
111.7
107.7
116.7
100.0
102.0
100.3
105.0
94.0
105.7
103.0
116.0
Water volume
Abundance
Water volume
X2
SD
8.5
11.4
8.0
11.8
21.4
12.2
14.2
17.5
3.3
12.3
10.7
6.2
Mean SD
3
1
3
3
5
8
6
10
4
4
0
0
0
1
0
0
0
0
3
3
4
8
0
0
Water volume
Abundance
Mean
78.2
79.0
78.0
79.0
85.2
79.7
78.9
77.7
81.0
79.0
80.0
78.3
SD
35.7
40.3
32.0
38.2
33.3
29.8
37.1
31.9
36.6
27.1
33.0
36.0
Mean
80.6
75.2
82.2
85.2
84.4
86.0
83.5
83.9
83.9
83.9
79.5
77.6
SD
13.8
8.8
10.8
6.5
11.3
12.4
12.9
16.4
28.6
15.2
16.6
14.9
SD
14.2
13.5
27.3
28.0
11.0
9.2
7.2
29.5
25.4
20.8
12.1
14.7
Mean
2
1
0
6
13
7
34
20
7
8
0
12
SD
1
2
0
3
10
13
28
17
3
7
0
15
Abundance
H3
Mean SD
1
2
0
0
0
1
0
0
1
1
17
2
24
17
10
8
0
0
0
0
0
0
8
7
Mean
105.7
108.1
110.9
117.7
111.1
107.9
117.9
117.9
127.4
121.0
107.7
109.2
SD
27.2
22.1
19.4
29.7
13.7
12.4
15.1
6.0
2.9
18.2
14.2
13.0
Water volume
X3
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Abundance
SG
SD
36.5
26.0
29.8
16.0
10.8
30.3
31.0
28.0
18.9
22.4
36.1
30.4
H2
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Abundance
X1
Mean
3
10
6
4
73
62
8
11
14
29
4
11
SD
3
7
8
6
62
69
11
11
19
23
7
10
Abundance
AS
Mean SD
0
0
0
0
0
0
0
0
13
22
2
3
5
9
0
0
3
5
3
5
0
0
3
4
Mean
77.8
79.4
65.6
62.3
71.8
68.6
68.9
67.9
67.3
65.1
68.5
61.6
SD
14.5
16.8
16.8
18.9
13.7
12.6
10.0
9.8
15.6
13.3
8.3
7.0
Mean SD
0
0
1
1
4
6
3
5
10 17
1
1
0
0
2
3
0
0
0
0
0
0
3
6
12
Table (2) Position and habitats of the sampling sites
Site Name
Small Giftun
Sabina 1 Sheltered
Sabina 1 Exposed
Sabina 2 Sheltered
Sabina 2 Exposed
MBS Sheltered
MBS Exposed
Abu Sadaf
Code
SG
H1
X1
H2
X2
H3
X3
AS
Substratum type (%)
Location
Exposure
Depth (m) Corals Rubbles Sand Algae and seagrass
Offshore
Exposed
25m
70
5
23
2
Offshore Highly Sheltered 0.5 - 1.5
8
25
60
5
Offshore Highly Exposed
8-12.5
60
27
10
0
Offshore
Sheltered
13-20
60
35
15
0
Offshore Highly Exposed
25 - 40
70
25
5
0
Inshore
Sheltered
7
2
3
45
50
Inshore
Exposed
9-12.5
10
30
40
20
Inshore
Exposed
1-2,5m
25
25
45
5
Table (3) Temperature and salinity at different sites on a bimonthly basis
Site
H1
X1
X2
H2
X3
H3
AS
SG
Temp
Winter SpringSummerAutumn
21.26 24.54 27.35 26.76
20.8 24.44
27
26.5
20.6 24.15
27
26
21.5 24.7
27.7
27
19.14 24.83 27.9
27
19.54 25.44 27.9
27.48
19.73 24.45 27.7
26.4
21.1 24.85 27.4
27.3
Salinity
Winter Spring SummerAutumn
40.03 39.4
39.9
40.1
40
39.8
39.9
39.8
39.9 39.3
39.9
40
40.01 39.75 39.9
39.8
40 39.35 39.9
40
40 39.55 39.9
39.9
40.1 39.4
39.5
40
40 39.85
40
39.2
13
Table (4) Mean annual abundance of different fish larval taxa at different sites SD=
standard deviation
SG
SPECIES
Muraenidae
Ophichthidae
Clupeidae
Spratelloides delicatulus
Engraulidae
Vinciguerria mabahiss
Benthosema pterotum
Synodontidae
Synodus sp.
Mean
0.45
2.00
H1
SD Mean
0.39
3.46
H2
SD
Mean
X1
SD
Mean
X2
SD
Mean
8.21 11.94 14.12 2.26 10.82 5.42 4.34 1.72
0.45 0.78
0.47
26.27 27.73
3.74 3.24 8.88
7.47 10.59
0.81 0.70 13.09
1.91 1.66
0.67 1.15
Dinematichthys iluocoeteoides 0.91 1.04
0.40 0.70
Atherinomorus lacunosus
25.84 2.99 12.51 5.45 16.55 12.91 0.00 0.00 9.12
Hypoatherina temmincki
5.69 4.40 16.29 4.98 1.21 2.10 1.21 2.10 2.57
Hyporhamphus gambrur
Exocoetidae
1.40
Platybelone argalus
Syngnathidae
Hippocampus
0.47
Fistularia commersonii
Myripristis murdjan
0.68 1.18
0.61 1.05 0.23
Sargocentron sp.
1.01 0.92 1.17
Apogon taeniatus
C. quinquineatus
Grammistes
0.23 0.39
Pseudoanthias sp.
4.21
Epinephelus sp.
0.67
Priacanthus hamrur
1.33 0.58
2.00
Caranax sp.
0.33 0.58
Trachinotus sp.
Gerres oyena
Haemulidae
Mulloides flavolineatus
4.76 4.45
1.61 2.80 13.32
Acanthopagrus bifasciatus
Pempheris vanicolensis
Abudefduf saxatilis
Pomacentrus sp1.
Pomacentrus sp2.
Pomacentrus sp3.
4.67 6.43
Paracaesio sordidus
0.40 0.70 0.81 1.40 0.47
Lutjanus1
0.40 0.35 1.17
Lutjanus2
0.70
Sphyraena barracuda
0.45 0.39
Mugilidae
4.44
Centrepyge multispinis
0.67
Scaridae
0.70
Chelinus sp.
Siganus sp.
0.23 0.39
Naso sp.
3.40 2.35
0.61 0.61
Acanthuridae
3.40 4.13
Triptrygiidae
Enneapterygius sp.
4.08 4.13
10.09 10.87
Omobranchus punctatus
0.68 0.00
0.81 0.92 2.10
P. ancylodon
Petroscirtes mitratus
3.65 6.33 13.24 7.64
Gobiidae
3.17 2.08 2.17 1.25
1.17
Microdesmidae
0.20 0.35 0.23
Eleoteridae
Callionymidae
0.91 0.78
0.23
Bothidae
0.45 0.78
Bothus pantherinus
0.68 1.18
Soleidae
0.23 0.39
Tetraodontidae
1.00 1.05
Diodon hystix
Ostraciion sp.
Mean
3.88 3.44 11.67 4.32 7.25 5.28 1.90 2.07 3.02
Number of taxa
28.00
5.00
4.00
17.00
23.00
H3
SD
0.81
10.62
14.60
8.79
1.07
1.21
X3
AS
Mean
SD
Mean
SD
Mean
SD
21.69
13.31
4.53
5.83
5.33 4.93
8.29 13.33
2.34
2.34
0.41
0.71
5.85
40.02
23.79
10.39
0.00
3.12
0.39
8.20
26.31 4.12 7.13 5.28
16.38 10.20 16.60 0.40
18.00
0.00
2.95
0.68
0.39
0.68
0.39
0.39
0.68
0.67
1.67
62.45
1.00
3.12
1.95
0.39
2.34
0.39
0.78
1.53
57.63
1.00
5.41
3.38
0.68
3.10
0.68
1.35
0.78
1.35
0.78
1.35
0.72
14.01
0.00
4.29
29.69
4.68
0.63
18.52
0.00
5.53
16.97
8.11
9.14
0.69
0.81
0.40
0.81
4.21
0.58
6.23
8.40 14.55
0.41
0.71
0.82
1.43
0.40
1.46
0.70
3.53
1.15
1.21
2.43
1.07
0.40
1.60
2.78
7.63 13.22
0.40
2.86
0.39
0.39
7.70
31.00
0.68
0.68
7.06
4.13
7.00
6.71
4.76
6.00
7.35
14
Mean
0.42
2.73
5.13
8.99
0.63
8.63
7.88
1.78
0.91
2.85
11.63
6.85
14.19
0.65
3.03
0.53
0.64
0.53
0.69
0.98
0.53
0.53
0.31
4.21
0.62
1.30
0.46
1.60
35.76
1.00
5.21
2.67
0.53
1.64
0.53
1.07
5.55
0.70
0.85
0.70
0.74
3.99
0.91
0.96
1.07
0.31
1.74
3.76
0.68
7.99
0.87
4.91
12.92
2.81
0.30
10.42
0.58
0.62
0.93
0.31
1.02
0.53
0.53
3.24
Inshore sites
Offshore sites
Fig.1. Map of the Red Sea, area of study and sampling sites
15
250
45
Abundance
40
No. taxa
200
35
e
c
n
a150
d
n
u
b
a
l
a100
u
n
n
a
n
a 50
e
M
30
25
20
15
10
5
0
0
n
a
J
b
e
F
r
a
M
r
p
A
y
a
M
l
u
n
J
u
J
month
g
u
A
p
e
S
t
c
O
a
x
a
tf
o
r
e
b
m
u
n
n
a
e
M
-5
v
o
N
c
e
D
Fig. 2. Monthly variation of larval fish abundance and number of taxa at all sites.
Fig. 3. The variation of larval fish abundance at different sites throughout the whole
period of study.
16
60
Taxa
50
40
a
x
ta
f 30
o
r
e
b
m 20
u
n
n
a
e 10
M
0
SG
H1
H2
X1
X2
H3
X3
AS
Site
Fig.4. The regional variation of the number of taxa throughout the whole period of study.
Others
20%
All Sites
A. lacunosus
19%
B. pterotum
4%
M.
flavolineatus
4%
Enneapterygi
us sp.
5%
G. oyena
13%
S. delicatulus
11%
P. mitratus
7%
V. mabahiss
8%
H. temmincki
9%
Fig. 7. Percentage contribution of the most abundant taxa
17
6
Diversity
Richness
5
Evenness
4
s
e
ci
d3
n
I
yit
sr2
e
vi
D
1
0
SG
H1
H2
X1
X2
H3
X3
AS
-1
Ste
Fig. 6. The regional variation of diversity indices (diversity, richness and evenness).
5
Richness
Evenness
4
Diversity
s3
e
c
i
d
n
I
y
it2
s
r
e
v
i
D
1
0
n
a
J
b
e
F
-1
r
a
M
r
p
A
y
a
M
n
u
J
l
u
J
g
u
A
p
e
S
t
c
O
v
o
N
c
e
D
Month
Fig. 7. Seasonal variations of the diversity indices (species richness, evenness and
species diversity).
18
‫آﺜﺎﻓﺔ و ﺗﻨﻮع ﻳﺮﻗﺎت أﺳﻤﺎك اﻟﺸﻌﺎب اﻟﻤﺮﺟﺎﻧﻴﺔ ﺑﺎﻟﻐﺮدﻗﺔ – اﻟﺒﺤﺮ اﻷﺣﻤﺮ – ﻣﺼﺮ‬
‫‪ 1‬؛‪2‬ﻣﺤﻤﺪ أﺣﻤﺪ أﺑﻮ اﻟﺮﺟﺎل؛ ‪3‬أﺷﺮف اﺑﺮاهﻴﻢ أﺣﻤﺪ؛ ‪3‬ﺻﻼح ﻏﺮﻳﺐ اﻻﺗﺮﺑﻰ؛ ‪4‬ﻣﺤﻤﺪ اﻟﻜﻮﻣﻰ و ‪1‬ﻣﺎﻳﻚ إﻟﻴﻮت‬
‫‪1‬ﻣﻌﻬﺪ اﻟﺪراﺳﺎت اﻟﺴﺎﺣﻠﻴﺔ – ﻗﺴﻢ اﻟﻌﻠﻮم اﻟﺒﻴﻮﻟﻮﺟﻴﺔ – ﺟﺎﻣﻌﺔ هﻞ ‪ -‬اﻟﻤﻤﻠﻜﺔ اﻟﻤﺘﺤﺪة‬
‫‪ 2‬اﻟﻤﻌﻬﺪ اﻟﻘﻮﻣﻰ ﻟﻌﻠﻮم اﻟﺒﺤﺎر و اﻟﻤﺼﺎﻳﺪ – ﻣﺤﻄﺔ ﺑﺤﻮث اﻟﻐﺮدﻗﺔ – اﻟﻐﺮدﻗﺔ اﻟﺒﺤﺮ اﻻﺣﻤﺮ – ﻣﺼﺮ‬
‫‪ 3‬ﻗﺴﻢ ﻋﻠﻮم اﻟﺒﺤﺎر‪ -‬آﻠﻴﺔ اﻟﻌﻠﻮم – ﺟﺎﻣﻌﺔ ﻗﻨﺎة اﻟﺴﻮﻳﺲ‬
‫‪ 4‬اﻟﻤﻌﻬﺪ اﻟﻘﻮﻣﻰ ﻟﻌﻠﻮم اﻟﺒﺤﺎر و اﻟﻤﺼﺎﻳﺪ – اﻻﺳﻜﻨﺪرﻳﺔ‬
‫ﺗﻤﺖ دراﺳﺔ ﻳﺮﻗﺎت أﺳﻤﺎك اﻟﺸﻌﺎب اﻟﻤﺮﺟﺎﻧﻴﺔ ﺑﺎﻟﻐﺮدﻗﺔ ﻋﻠﻰ اﻟﺴﺎﺣﻞ اﻟﻤﺼﺮى ﻟﻠﺒﺤﺮ اﻻﺣﻤﺮ ﻓﻰ اﻟﻤﻨﺎﻃﻖ‬
‫اﻟﻤﻜﺸﻮﻓﺔ و اﻟﻤﺤﻤﻴﺔ ﻣﻦ اﻟﺸﻌﺎب اﻟﻤﺮﺟﺎﻧﻴﺔ ﻓﻰ ﻣﻨﺎﻃﻖ ﺳﺎﺣﻠﻴﺔ و أﺧﺮى ﺑﻌﻴﺪة ﻋﻦ اﻟﺸﺎﻃﻰء‪ .‬ﺗﻢ ﺟﻤﻊ ﻋﻴﻨﺎت‬
‫اﻻآﺘﻴﻮﺑﻼﻧﻜﺘﻮن ﺑﺎﺳﺘﺨﺪام ﺷﺒﻜﺔ ﺑﻼﻧﻜﺘﻮن ﺑﺼﻮرة ﺷﻬﺮﻳﺔ ﻓﻰ اﻟﻔﺘﺮة ﻣﻦ دﻳﺴﻤﺒﺮ ﺣﺘﻰ ﻳﻨﺎﻳﺮ ‪ .2005‬و ﻗﺪ ﺗﻢ ﺟﻤﻊ‬
‫‪ 1799‬ﻳﺮﻗﺔ ﺗﻤﺜﻞ ‪ 63‬وﺣﺪة ﺗﺼﻨﻴﻔﻴﺔ ﻣﺨﺘﻠﻔﺔ و ﺗﻨﺘﻤﻰ إﻟﻰ ‪ 44‬ﻓﺼﻴﻠﺔ و ‪ 16‬رﺗﺒﺔ ﻣﻦ اﻷﺳﻤﺎك‪ .‬آﺎﻧﺖ اﻟﻮﻓﺮة اﻟﻜﻠﻴﺔ‬
‫ﻟﻠﻴﺮﻗﺎت ‪ 1993‬ﻟﻜﻞ ‪ 1000‬ﻣﺘﺮ ﻣﻜﻌﺐ ﻣﺘﺮ ﻣﻴﺎﻩ‪ .‬أوﺿﺤﺖ اﻻﺧﺘﺒﺎرات اﻻﺣﺼﺎﺋﻴﺔ وﺟﻮد ﻓﺮوق ﻣﻌﻨﻮﻳﺔ ﺑﻴﻦ آﺜﺎﻓﺔ‬
‫اﻟﻴﺮﻗﺎت ﺑﻴﻦ اﻟﻤﻮاﻗﻊ و ﻟﻜﻦ ﻟﻴﺲ ﺑﻴﻦ اﻟﺸﻬﻮر‪ .‬اﺣﺘﻮى اﻟﻤﻮﻗﻊ اﻟﺴﺎﺣﻠﻰ اﻟﻤﺤﻤﻰ )‪ (H3‬ﻋﻠﻰ أﻋﻠﻰ آﺜﺎﻓﺔ ﻟﻠﻴﺮﻗﺎت ﺑﻴﻨﻤﺎ‬
‫اﺣﺘﻮى اﻟﻤﻮﻗﻊ اﻟﺴﺎﺣﻠﻰ )‪ (AS‬اﻟﻤﻜﺸﻮف ﻋﻠﻰ أﻗﻞ آﺜﺎﻓﺔ ﻟﻠﻴﺮﻗﺎت‪ .‬آﻤﺎ ﺳﺠﻠﺖ ﻓﺮوق ﻣﻌﻨﻮﻳﺔ ﺑﻴﻦ اﻟﻤﻮاﻗﻊ اﻟﺸﺎﻃﺌﻴﺔ و‬
‫اﻟﺒﻌﻴﺪة ﻋﻦ اﻟﺸﺎﻃﻰء ﺑﺎﻟﻨﺴﺒﺔ ﻟﻌﺪد أﻧﻮاع اﻻﺳﻤﺎك‪.‬‬
‫ﻣﺜﻠﺖ اﻷﻧﻮاع اﻟﺘﺎﻟﻴﺔ أﻋﻠﻰ آﺜﺎﻓﺔ ﺑﻴﻦ اﻷﻧﻮاع ﺣﻴﺚ آﻮﻧﺖ ﻣﺠﺘﻤﻌﺔ ﻧﺴﺒﺔ ﺗﺼﻞ إﻟﻰ ‪ %82.5‬ﻣﻦ ﻋﺪد اﻟﻴﺮﻗﺎت اﻟﺘﻰ ﺗﻢ‬
‫ﺟﻤﻌﻬﺎ ﻋﻠﻰ ﻣﺪى اﻟﺪراﺳﺔ‪:‬‬
‫‪Atherinomorus lacunosus (Atherinidae), Spratelloides delicatulus (Clupeidae),‬‬
‫‪Gerres oyena (Gerreidae), Hypoatherina temmincki (Atherinidae), Petroscirtes‬‬
‫‪mitratus (Blennidae), Vinciguerria mabahiss (Phosichthyidae), Enneapterygius sp.‬‬
‫‪pterotum‬‬
‫‪Benthosema‬‬
‫‪(Mullidae),‬‬
‫‪flavolineatus‬‬
‫‪Mulloides‬‬
‫‪(Triptrygiidae),‬‬
‫‪(Myctophidae) and Gobiidae,‬‬
‫و ﻣﺜﻞ اﻟﻨﻮع اﻻول ﻓﻘﻂ ﻧﺴﺒﺔ ‪ %19‬ﻣﻦ ﻣﺠﻤﻮع اﻟﻴﺮﻗﺎت اﻟﺘﻰ ﺗﻢ ﺟﻤﻌﻬﺎ ﻃﻮال ﻓﺘﺮة اﻟﺪراﺳﺔ ﺑﻜﺜﺎﻓﺔ ‪ 113‬ﻳﺮﻗﺔ ﻟﻜﻞ ‪ 1000‬ﻣﺘﺮ‬
‫ﻣﻜﻌﺐ ﻣﺎء ﺑﻴﻨﻤﺎ آﺎﻧﺖ ﻓﺼﻴﻠﺔ ‪ Soleidae‬و ﻓﺼﻴﻠﺔ ‪ Siganidae‬اﻗﻞ اﻟﻤﺠﻤﻮﻋﺎت آﺜﺎﻓﺔ‪.‬‬
‫‪19‬‬