The Ecological Characteristic of The Fish Assemblage at Southern part of Shatt AL-Arab River

Amjed K. Resen

Department of Fisheries and Marine Resources, College of Agriculture University of Basrah, Basrah, Iraq

*Corresponding Author E-mail: Amjedkrr@yahoo.com

Abstract:

The fish assemblage and some ecological variables for Shatt Al-Arab Riverin Abi Al-Khasib area near the port of Abu Flus, during 2016 and 2017 was used to assess the effect of environmental conditions on seasonal variations in fish species abundance and distribution patterns. A total 1531 fishes belonging to 28 species and 12 families, of, including 16 freshwater, 12 marine species, 8 native fish and 8 alien fish. Cyprinidae the dominant family, was represented by eleven species. Coptodon. zilliwas the most abundant species numerically comprising 23.2%, followed by Carassius. auratus (14%), Liz. subviridis (11%), Planilizaabu (10%), Tenualosailisha (9%) and Acanthopagrusarabica (8%). The recorded salinity mean was 1.7‰. Numerical diversity index 2.605-2.18, evenness index were (0.83-0.686) and richness were 1.546-0.950.

KEY WORDS: Fish, ecological, Shatt Al-Arab river.

INTRODUCTION:

The difference in the distribution of organisms is a fundamental issue in ecology, since several factors dominate the life variability, as they are addressed by many scientific references that may be related to biodiversity (Whittaker et al.,2001) In domestic environments, species richness may be regulated by biotic factors, and biotic factors such as interactions, which include competition, predation and environmental needs, play a large and influential role in species diversity (Oberdorffet al., 1998). The description of the composition of the fish community is based on the use of environmental evidence of diversity, including the richness guide, which expresses the richness of the study area in terms of the numerical abundance and quality of fish, and the diversity of the species in terms of number, weight, and evenness, And the relative abundance and similarities used to calculate the degree of similarity in the qualitative composition of fishing samples. The major river source in the Arabian Gulf is the Shatt-Al-Arab being located at the head of the Gulf and being fed by the Euphrates, Tigris and Karun rivers. Bibiket at. (1970) considered this estuary to be one of the most productive areas in that region. The water level of Shatt Al-Arab River is affected by the tide of the Gulf as well as discharging rates of Tigris and Euphrates rivers. Many researchers have emphasized the importance of this evidence in describing and studying the community and fish populations in different species. (Ludwig and Reynolds, 1988; Hubbell, 2001; Pihl and Wennhage, 2002). Several studies in Iraq have focused on the registration and classification of fish in Iraqi environments (Khalaf, 1961, Mahdi, 1962; Banister, 1980; Dham, 1982 and Coad, 2010). Al-Nasiri and Shamsul-Hoda (1975) conducted a survey of bone fish in the Shatt Al-Arab in the area extending from Abu Al-Khasayb to Garma Ali, bringing together 32 species, including 12 sea species. Some studies Al-Hassan and Hussain, (1985) Al-Hassanand Naama (1986) on the entry and spread of some marine fish to the Shatt Al-Arab, and some studies described the composition of the Iraqi fish community in the southern region, which usually consists of native species and seasonal species exist either for breeding or nutrition or to spend a period of life cycle, Kindle is a rare occurrence occasional species in the flat Aqueous (Al-Hassan and Naama, 1986). During the last years, the Mesopotamian rivers were suffering from various problems amongst them new hydrological projects, several large dams in Turkey, Syria, Iran, and Iraq have diverted water from the Tigris and Euphrates and their tributaries for irrigation, flood control, and hydroelectric power. Prior to the end of the twentieth century the discharge rate of the Tigris ranged from 3000 m3/s to less than 500 m3/s, while that of the Euphrates ranged from 2000 m3/s to less than 250 m3/s (Plaziat and Younis, 2005). Moreover, the diversion of Karun River towards the Iranian side was put in practice during 2009 (Hameed and Aljorany, 2011). Study (Mohumedet al., 2012)

A total 1460 fishes belonging to 40 species and 19 families. The present study aims to study the fish composition of the Shatt al-Arab in Abi Al-Khasib area near the port of Abu Flus.

Materials and Methods:

The Shatt Al-Arab River is formed by the confluence of Tigris and Euphrates rivers at Qurna, flows southeastern direction to open in the Arabian Gulf south of Al-Fao city. The total length of Shatt Al-Arab River is about 204 km, the width varies from 400 to 1500m, and hundreds outlets in the form of small rivers and canals are found on both sides of Shatt Al-Arab River (Al-Lami, 2009). Its maximum depth is ranged from 9m in Dayer site to 10m in in Abi Al-Khasib area near the port of Abu Flus. Sampling on the river was conducted once a season from October 2016 to July 2017. The sampling sites in Abi Al-Khasib area near the port of Abu Flus. (Fig. 1 south of Basrah. Fish were sampled seasonally, autumn (October) winter (January) spring (March) and summer (July). at each site using seine net (50x3m , 10mm mesh size). All fish collected were identified to species and counted. Species identification was based on Beckman (1962), Carpenter et al. (1997) and Coad (2010). Besides the fish sampling, a total of five variables were used to describe environmental conditions at each of the three sites. These variables were water temperature, salinity, dissolved oxygen and pH measured by YSI 556 MPS instrument, and transparency by Secchi disc. The analysis of the nature of the fish assemblage in the three sites was carried out by the following methods and indices: relative abundance (Odum, 1970), diversity index (Shannon and Weaver, 1949), evenness index (Pielou, 1977), richness index (Margalef, 1968) and similarity index (Boesch, 1977). were used to test the significance of the different environmental factors on fish species composition.

Results:

Ecological factors

Seasonal changes in some ecological factors in the three study sites of Shatt Al-Arab River are given in Table 1. Water temperature, dissolved oxygen and pH exhibited no significant no differences in the three site (p≤0.05). Water temperature ranged from 16 C^o during winter to 31.5 C^o during summer. Dissolved oxygen ranged from 7.3 mg/l during summer to 12.7 mg/l during winter. While pH changed from 7 during winter to 8 during summer. Salinity changed from 1.2‰ during winter to 2.4 ‰ during summer.

Table 1. Seasonal variations in the ecological factors at the three studied sites in Shatt Al-Arab during 2016-2017.

Season	Water Temperature (°C)	Salinity	Dissolved Oxygen (mg/l)	pH	Transparency (cm)
Autumn	21.5	1.9	9.3	7.8	44
Winter	16	1.2	12.7	7	52
Spring	19.6	1.5	8.8	7.5	40
Summer	31.5	2.4	7.3	8	45
Mean	22.1	1.7	9.5	7.5	45.25

Species distribution:

A total of 28 fish species belonging to 12 families were caught from the sampling sites in Abi Al-Khasib area near the port of Abu Flus, including 16 freshwater, 12 marine species, 8 Native fish and 8 Alien fish (Table 2). The most diverse family was Cyprinidae with eleven species (39% of species). Mugilidae and Clupeidaewere represented by three (10%).

Table 2. Nomenclature of the fish sampled from the site of Shatt Al-Arab.

Species	Family
Alburnusmossulensis*º	Cyprinidae
Acanthobramamarmid*º	Cyprinidae
Aspiusvorax*º	Cyprinidae
Acanthobramalissneri*º	Cyprinidae
Barbusluteus*º	Cyprinidae
Barbusgrypus*º	Cyprinidae
Carassiusauratus+º	Cyprinidae
Cyprinuscarpio+º	Cyprinidae
Ctenopharyngodonidella+º	Cyprinidae
Hemiculterleucisculus+º	Cyprinidae
Lyciobarbusxanthopterus+º	Cyprinidae
Planilizaabu*º	Mugilidae
Liza subviridis	Mugilidae
Liza klunzingeri#	Mugilidae
Tenualosailisha#	Clupeidae
Anodontostomachacunda#	Clupeidae
Amblygastersirm#	Clupeidae
Bathygobiusfuscus#	Gobiidae
Thryssahamiltoni#	Engraulidae
Thryssawhitheadi#	Engraulidae
Acanthopagrusarabica#	Sparidae
Ilishacompressa#	Pristigasteridae
Mystexpelusius*º	Bagridae
Pocilialatipinna+º	Poecillidae
Brachirusorientalis#	Solidae
Coptodonzillii+º	Cichlidae
Orechromisaureus+º	Cichlidae
Silagosihama#	Sillaginidae

*Native fish, +Alien fish, #Marine fish, Freshwater fish Species abundance

A total of 1531 fish were collected from the Shatt Al-Arab River (Abi Al-Khasib area near the port of Abu Flus). Table 3 explained the seasonal variations in the relative abundance of different species at site from October 2016 to July 2017. C. zilli.

was the most abundant species of the fish assemblage of Shatt Al-Arab River comprising 23.2% of the total numbers followed byC. auratus(14%), L.subviridis(11%), P. abu(10%), T. ilisha(9%) and A. arabica(8%). (Table 3).C. zilliwas dominant in autumn; spring and summer;C. auratusin winter.There were seasonal variations in the number of species in site.The highestnumbers were 28species captured duringAutumn and summer.

Dominant fish species changed locally the site (Table 3) C. zilliwas dominant in autumn, spring and summer C. auratus in winter. The most dominant species constituted 93.2% of the total number of individuals captured in this site includedC. zilli (22.8%, 23%, 25.9%) and C. auratus (21.55).

Table (3) Seasonal variations in the relative abundance of different species in Shatt Al-Arab during 2016-2017.

	Number of fish(Ratio%)
Species	Autumn	Winter	Spring	Summer	Total
C. zilli	75 (22.8)	(12.1) 13	(23) 123	(25.9) 145	(23.2) 356
C. auratus	(13.7(45	(21.5) 23	(12.5) 67	(14)78	(14) 213
L. subviridis	(3.3)11	(2.8)3	(12.1) 65	(15.5) 87	(11) 166
P. abu	(16.4) 54	(12.1)13	(6.1) 33	(8.5)48	(10) 148
T.ilisha	(1.2)4	(19.6) 21	(19) 102	(2)10	(9)137
A. Arabica	(7)23	(1.8)2	(6.3) 34	(10.3) 58	(8)117
O. aureus	(3.6)12	(0.9)1	(5.5) 30	(11)61	(7)104
A. vorax	(2.7)9	(15.8)17	(2.7) 15	(1)5	(3)46
L. klunzingeri	(3.6)12	0	(3.3) 18	(2.3)13	(3)43
A. lissneri	(3.3)11	0	(2.8) 15	(1.1)6	(2)32
A. mossulensis	(4.8)16	0	0	(1.4)8	(1.5)24
L. xanthopterus	(3.6)12	0	(1.5)8	(0.5)3	(1.5)23
A. marmid	(0.9)3	(6.5)7	0	(2)10	(1.3)20
B.grypus	(0.9)3	(0.9)1	(0.7)4	(1)5	(1)13
C.carpio	(0.6)2	(0.9)1	(0.9)5	(1)4	(1)12
A. chacunda	(2.1)7	0	0	(0.5)3	(1)10
B.luteus	(1.5)5	0	(0.5)3	(0.2)1	(0.5)9
P. latipinna	(1.5)5	(0.9)1	(0.4)2	(0.2)1	(0.5)9
T. hamiltoni	(0.6)2	0	(0.5)3	(0.2)1	(0.4)6
T. whitheadi	(0.6)2	(0.9)1	(0.4)2	(0.2)1	(0.4)6
I. compressa	(0.6)2	0	0	(1)4	(0.4)6
A. sirm	(0.3)1	(2.8)3	(0.2)1	(0.2)1	(0.4)6
C. idella	(0.9)3	0	(0.4)2	(0.2)1	(0.4)6
S. sihama	(0.9)3	0	(0.2)1	(0.2)1	(0.3)5
M. pelusius	(0.6)2	0	(0.4)2	(0.2)1	(0.3)5
H. leucisculus	(0.6)2	0	(0.2)1	(0.3)2	(0.3)5
B. orientalis	(0.3)1	0	0	(0.2)1	(0.1)2
B. fuscus	(0.3)1	0	0	(0.2)1	(0.1)2
Total fish no.	328	107	536	560	1531
Total species no.	28	14	22	28

Diversity indices:

Seasonal variations in diversity, richness and evenness indices in the site were illustrated in Figure 3. Higher diversity values noticed autumn (2.605). The lowest values were in winter (2.18). The highest values of evenness index was (0.83) recorded in winter and the lowest values were in summer (0.686). The highest values of richness were recorded in autumn (1.546) and the lowest values were in spring (0.950).the relationships between fish species distribution and environmental variables in Shatt Al-Arab river (Abi Al-Khasib) are given in table (3). The results showed that there was a positive correlation between temperature, salinity, pH and diversity values while the correlation was negative (non-significant) with oxygen and transparency. A positive correlation between oxygen and transparency was recorded with of evenness and negative correlation with temperature, salinity and pH As for richness, the correlation (not significant) was positive with all factors except temperature. The highest positive correlation was recorded between oxygen and evenness (0.94). The highest negative correlation between the temperature and evenness(0.92).

Fig. 2. Seasonal variations in ecological indices of fish assemblage in the Shatt Al-Arab during 2016-2017

Table (4) The correlation values between environmental factors and ecological indices.

W. Temp.	Salinity	D. O.	pH	Transp.
0.102387	0.349462	-0.34028	0.548643	-0.45642	Species Diversity index H
-0.91755	-0.85089	0.943026	-0.83363	0.580758	Evenness
-0.13627	0.048628	0.36177	0.004236	0.505415	Species richness

Discussion:

Water temperature is one of the most important environmental factors associated with the availability of aquatic organisms (Araujoet al.,2000). Water temperature is a determinant of the environment, they affect the presence, density, distribution of biology and biological physiological effects and their impact on the physical and chemical properties of water (Kennish, 1986). Temperatures showed varying seasons during the study period It is consistent with many previous studies Hussein and Attee, 2000;Resen,2001; Mohamed et al .,2012).

The recorded salinity values fluctuated if they are relatively high in summer and almost evenly betweenother seasons. This is due to the low salinity of the high levels of the Shatt Al-Arab River and the lack of progress of the salt tide coming from the Arabian Gulf during the study period.whereas, Mahdi et al. (2002) stated that the salinity of Shatt Al-Arab River at Abu Al-Khaseeb with mean value 1.1‰ during 1997-1998, also Mohamed et al. (2012) with mean value 2.4‰ during 2010-2011. The results of the statistical analysis showed a positive correlation between salinity values and water temperature (r=0.97). The pH values were the alkaline direction. This result is consistent with most of the studies carried out on Shatt al-Arab (Hussein and Attee,2000; Resen,2001; Mohamed et al.,2012).The highest oxygen values were recorded during the cold months due to increased solubility and low degradation of organic matter (Saad and Antoine,1978). While the lowest values were recorded during the warmer months due to several reasons, including decreased melting with high water temperature (Karlsenet al., 2000). Transparency showed high values in winter and decrease in Warm seasons that abundance of phytoplankton in warm seasons compared

The freshwater and marine species constituted66. 95% and 33.05% of this assemblage, respectively. The most dominant species were C. zilli, C. auratus, L. subviridis, L. abu, T.ilisha, A. Arabica, O. aureus and all consisted 81% of the total number of individuals in this site.types of dominated species and values of diversity indices. However, most previous surveys have been conducted the region between Garmat Ali and Abu Al-Khasib of the Shatt Al-Arab River concerning the fish fauna (Hussainet al., 1989; 1995; 1997; Mohamed et al., 2012). All these surveys indicated the occurrence of several marine species Hussainet al. (1989) found 33 species, 14 of them marine species. Hussainet al. (1997) mentioned 25 species, 7 of them marine species; Mohamed et al. (2012) found 22 species, 12 of them marine species. Compared with these studies, the present study reported almost equal percentage of marine species in this region.

The importance of the more abundant species varied considerably in of the site of the site. C. zilliwas captured in highest numbers principally. The species was the most dominant species in many Iraqi inland waters now is an exotic fish that invaded Iraqi waters especially in recent years because it bears environmental changes Hussein, 2000; Resenetal., 2016). The study showed local fish such as B. luteus, B. grypus and L. xanthopterusthis may be due to the relative improvement in water quality in the study area, as they did not register Mohamed et al., (2012) L.xanthopterus in their studies in the Hamdan area.

In the current study the diversity values were lowbecause of the dominance of species in many numbers such as C.zilli and C.auratus that were they found that were they found by(Mohamed et al., 2012; Resenetal., 2016). The rich index values were slightly fluctuated during the study period due to the limited variability in the number of species. This is consistent with the study Younis (2005) and Resenetal. (2016). The low correlation between environmental factors and diversity index except oxygen and the evenness, salinity values did not significantly affect diversity index as in the past few years For the relative improvement in the water quality of Shatt al-Arab rever as in a studies (Younis, 2005; Mohamed et al ., 2012; Resenetal., 2016).

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Received on 17.04.2018 Modified on 21.05.2018

Research J. Science and Tech. 2018; 10(3):217-222.

DOI: 10.5958/2349-2988.2018.00030.X