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Microbial pollution indicators along the Egyptian coastal waters of Suez and Aqaba Gulfs and Red Sea

Ibrahim, Hassan A.H.; Farag, Aida M.; Beltagy, Ehab A.; El-Shenawy, Mohamed A.

The Journal Of The Egyptian Public Health Association: December 2011 - Volume 86 - Issue 5 and 6 - p 111–118
doi: 10.1097/01.EPX.0000407209.05371.82
Original articles
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Background Nowadays, the Egyptian coasts of the Aqaba and Suez Gulfs, and the Red Sea proper, are under the direct effects of many recreational resorts, urban agglomeration, marine shipping, activity of the phosphate industry, fishing ports, and limited freshwater and sewage surfaces. Therefore, the water, especially those used for recreational activities, must be of a very good quality to be able to increase the national income.

Objectives To investigate the conventional water-quality bacteria, total coliforms (TC), Escherichia coli (EC), and fecal streptococci (FS), in the Egyptian coastal waters of Suez and Aqaba Gulfs and the Red Sea.

Materials and methods A total of 2372 surface water samples were collected from 42 sampling sites during 12 years (1998–2009) to detect and estimate TC, EC, and FS using the membrane filtration method.

Results On the basis of the national and international bacterial standards, 540 samples (22.8%) out of 2372 were found to exceed the guide values (positive samples) and were not accepted for marine recreational purposes. During the course of the study, Suez Gulf showed the highest positive records of 54 and 96 for TC and EC, respectively, whereas FS recorded 94 and 88 positive samples in the Red Sea and Suez Gulf, respectively. The lowest positive records were found in 1998 and 2009, whereas the highest were in 2000 and 2002–2004. The highest polluted sampling sites were recorded in Su7 (Suez Gulf), Aq2 (Aqaba Gulf), and Re15 (Red Sea), and were generally affected by sewage disposal and/or anthropogenic influences.

Conclusion and recommendations The most polluted sites were in the Suez Gulf, reaching 238 sites, followed by 194 sites in the Red Sea, whereas the Aqaba Gulf had only 108 polluted sites. Moreover, the most polluted sample locations throughout the study were Su7, Aq2, and Re15, without implementation of corrective actions from authorized organizations. The data of the current study must be taken into consideration by the government for a safer and cleaner seawater in the eastern Egyptian coasts, especially those in which critical limitations in terms of microbial pollution are found.

Department of Marine Microbiology, National Institute of Oceanography and Fisheries, Kayet Bay, Alexandria, Egypt

Correspondence to Dr Hassan A.H. Ibrahim, Department of Marine Microbiology, National Institute of Oceanography and Fisheries, Kayet Bay, 21556 Alexandria, Egypt Tel: +203 4299776; fax: +203 480 1174; e-mail: doctorhassan10@yahoo.com

Received July 27, 2011

Accepted October 2, 2011

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Introduction

The Egyptian coasts of the Aqaba and Suez Gulfs, and the Red Sea proper, are considered to be relatively undisturbed because of the low population density. The subtropical climate and the healthy coral reefs with their colorful and diverse marine landscape represent the main assets for ecotourism and are a major resource in these areas, and consequently a source of national income. The ecotourism infrastructure is continuously developing: three international airports (Sharm El-Sheikh, Hurghada, and Marsa Alam) and a large number of resorts have been established in many new areas along the Egyptian coast and extend south to the border of Sudan 1.

Nowadays, these coasts are under the direct effects of many recreational resorts, urban agglomeration, marine shipping, activity of the phosphate industry, fishing ports, and limited freshwater and sewage surfaces. Therefore, the water, especially those used for recreational activities, must be of very good quality 2.

Fecal pollution bacteria, that is, total coliform (TC), Escherichia coli (EC), and fecal streptococci (FS), are used as sanitary parameters for the evaluation of water quality 3. It is also known that these indicators are associated with disease-causing genera of importance to public health 4–7.

In fact, coliforms are themselves not normally causes of serious illness; they are easy to culture and their presence is used to indicate that other pathogenic organisms of fecal origin may be present. EC is a subgroup of the fecal coliform group. Unlike the general coliform group, EC are almost exclusively of fecal origin and their presence is thus, an effective confirmation of fecal contamination. Although most EC bacteria are harmless and found in significant quantities in the intestines of people and warm-blooded animals, some strains can cause serious illness in humans 8.

In this investigation, we studied the conventional pollution indicator bacteria, TC, EC, and FS, as water-quality indicators in the Egyptian coastal water of Suez and Aqaba Gulfs and the Red Sea proper to assess the esthetic and sanitary quality of these coastal areas during 12 years (1998–2009).

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Materials and methods

Study area

Red Sea is a deep semienclosed and narrow basin that lies between 12–30°N and 32–44°E, and has a length of about 1930 km and an average width of 280 km (Fig. 1). It is connected to the Indian Ocean through the Bab El-Mandab strait and extends northward to Sinai Peninsula, which divides it into the shallow Suez Gulf (250 km long; and average width of 32 km and an average depth of 64 m) and the deep Aqaba Gulf (150 km long; an average width of 16 km and an average depth of 650 m). The average depth of the Red Sea is 490 m 9. Forty-two sampling sites were fixed to represent the recreational areas and towns, ports, fishing ports, and some protectorate areas. Twelve sites were in the Aqaba Gulf, 15 sites in the Suez Gulf, and 15 sites along the Red Sea proper.

Figure 1

Figure 1

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Sampling

Surface water samples were planned to be collected bimonthly from 42 sampling sites during 12 years (1998–2009) and to be analyzed microbiologically for the bacterial indicators of fecal pollution. However, the sample collection was not uniform throughout the time course of the study. From 1998 to 2004, the seawater samples were collected bimonthly (i.e. six field trips per year) from 42 sites, whereas from 2005 to 2009, the field trips were reduced to only five per year and the sites were also reduced. These difficulties resulted in a total of 2372 samples being investigated.

The code numbers and location names of these sites are shown in Fig. 1 and Table 1. Seawater sampling technique was performed in duplicate according to the International Organization for Standardization (ISO) 5667/1 using 500-ml sterile bottles and a special sampler, 50 cm below the water surface at a shallow depth of about 1 m 10.

Table 1

Table 1

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Microbiological analysis

The bacterial indicators, TC, EC, and FS, were enumerated on m-Endo-les agar, m-FC agar, and m-Enterococcus agar (Difco, Difcom, Villeneuve-d'Ascq, France), respectively. The membrane filtration technique was used. Sample volumes of 1 and 10 ml were used for water testing, with the goal of achieving a final desirable colony density range of 20–60 colonies per filter. Contaminated sources may have the required dilution to achieve a countable membrane. An appropriate volume of a water sample (1, 10, or 100 ml) according to the contamination picture was drawn through a membrane filter (0.45 µm) through a vacuum pump. The filter was placed on a Petri dish containing appropriate media and was incubated at a suitable temperature. Ten random characteristic colonies from each sample were subcultured, confirmed, and the final counts were calculated as cfu/100 ml according to the ISO 9308/1 11 and ISO 7899/2 12. The bacteriological analysis was performed in situ after sampling in a mobile laboratory van. Complete analysis and confirmation tests were performed at the National Institute of Oceanography and Fisheries laboratories in Suez and Hurghada. The bacterial counts were figured in logarithmic form.

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Hydrographical analysis

Hydrographical parameters including water temperature (°C), salinity, (S‰), dissolved oxygen mg/L, and pH were measured in situ at each station using a conductivity temperature depth device (YSI Incorporated - 6000, 556 MPS, USA).

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Results and discussion

The criteria for water quality must be based on parameters that relate primarily to health hazards. Other considerations may include parameters that relate to esthetic aspects of the beach area, fishing, and shellfish culture. Coastal waters receiving discharges of sewage, storm water, and other animal wastes may contain disease-causing bacteria, viruses, and multicellular parasites. Unfortunately, there is no single test that will adequately detect quantitatively the wide spectrum of pathogens that might be present. For this reason, major emphasis has been placed on fecal coliform or FS measurements as an evidence of contamination from warm-blooded animal waste discharges 13.

The guide standards for marine recreational waters of the Egyptian Ministry of Health 14, European Commission 15, and WHO 16, which accept the guide values of the investigated bacteria up to 500 cfu/100 ml of marine waters for TC and 100 cfu/100 ml for both EC and FS. The combination of the three indicators is likely to offer a global picture of water 3.

In general, most of the investigated sites were found to harbor the indicator bacteria. However, 14 (Aq2, Aq3, Aq11, Su1-b, Su1-c, Su3, Su7, Su9, Su13, Re4, Re7, Re8, Re11, and Re15) of the 42 sites showed bacterial counts ranging from slightly to extremely higher than the current standards. The highest positive records were found during 2000 and 2002–2005 (Table 3).

According to the European and Egyptian current standards, for recreational purposes, 540 of 2372 samples (22.8%) investigated during 1998–2009 were not acceptable, whereas 1832 of 2372 samples (77.2%) were acceptable. Moreover, using TC as the indicator bacteria, 104 (4.4%) samples (54, 20, and 30 sites in the Suez Gulf, the Aqaba Gulf, and the Red Sea, respectively) out of 2372 were polluted. However, EC and FS recorded 214 (9.02%) samples (96, 48, and 70) and 222 (9.36%) samples (88, 40, and 94) at the same regions, respectively (Table 2).

Table 2

Table 2

In the Suez Gulf, there were 54 polluted sites with TC out of 2372 (Table 2). The most polluted site during the investigation period in relation to the year was Su7 (100%) in 2003, followed by Su1-c (58.3%). The year with the highest TC counts was 2003, with 10 positive records, followed by 2002 and 2006 with, eight positive records. The years with the lowest TC counts were 1998, 2005, 2007, and 2008, which had only two positive records (Fig. 2). There were 96 sites polluted with EC out of 2373 (Table 3). The most polluted site along the period of investigation was always Su7 (100%), followed by Su1-c (83.3%). The highest positive record years in EC counts were 2003 and 2004, with 12 positive records followed by 2002, 2005, and 2006 with 10 positive records (Fig. 2). There were 88 sites polluted with FS out of 2372 (Table 2). The most polluted site along the period of investigation was always Su7 (100%), followed by Su1-b (66.6%). The years with the highest FS counts were 2002 and 2003, with 10 positive records, followed by 2000, 2001, and 2005 with eight positive records. The year with the lowest FS count was 1998, with only two positive records (Fig. 2).

Figure 2

Figure 2

Table 3

Table 3

In the Aqaba Gulf, 20 sites showed unacceptable counts of TC (Table 2). The most polluted site along the period of investigation was always Aq2 (41.7%), followed by Aq11 (25%). The year with the highest TC counts was 2000, with eight positive records, followed by 2001 and 2002 with four positive records (Fig. 3). There were 48 sites polluted with EC (Table 2). The most polluted site along the period of investigation was always Aq2 (10/12), followed by Aq3 (41.7%). The year with the highest EC count was 2000, with eight positive records, followed by 2001, 2003, and 2005 with six positive records. The year with the lowest EC was 1998, with no positive records (Fig. 3). There were 40 sites polluted with FS (Table 2). The most polluted site along the period of investigation was always Aq2 (83.3%), followed by Aq8 (25%). The years with the highest FS counts were 2000, 2001, 2003, and 2005, with six positive records, followed by four positive records for 2006. The year 2009 was the cleanest because it had no positive records (Fig. 3).

Figure 3

Figure 3

In the Red Sea proper, 30 sites recorded unacceptable TC counts (Table 2). The site with the highest count along the period of investigation was always Re15 (66.6%). The year with the highest TC count was 2002, with 12 positive records, followed by 2000 with six positive records. The year 2009 had no positive records, and so it was considered the cleanest year with regard to TC (Fig. 4). There were 70 sites polluted with EC (Table 2). The most polluted site along the period of investigation was always Re15 (91.7%), followed by Re11 (58.3%). The year with the highest EC count was 2002, with 14 positive records, followed by 2004 and 2006 with 10 positive records. The year with the lowest EC count was 2009 with only two positive records (Fig. 4). There were 94 sites polluted with FS (Table 2). The most polluted site along the period of investigation was always Re15 (91.7%), followed by Re11 (58.3%). The year with the highest FS counts was 2002, with 12 positive records, followed by 2001, 2003, 2004, and 2005, with 10 positive records. The year 1998 was the cleanest one, without any positive records (Fig. 4).

Figure 4

Figure 4

Our data confirm that the conventional water-quality bacteria, TC, EC, and FS, are a representative tool to assess microbial water pollution in the coastal waters. Our data are in the agreement with the data obtained by several workers in other areas all over the world 1,3,4,13,17–21. For instance, in Brazilian tropical and subtropical marine surface waters, Hagler et al.22 investigated the microbial pollution indicators and supported the use of coliforms or FS as indicators of recent fecal pollution in tropical marine waters, and yeasts or heterotrophic bacterial counts as complementary indicator methods for these waters. In the Gaza Strip, Elmanama et al.23 studied the sand quality of the microbiological beach in comparison with the seawater quality, and they evaluated the microbial sand content for fecal coliforms, FS, Salmonella, Shigella, and Vibrio. Seawater samples were subjected to similar evaluation. Pseudomonas, yeast, and mold counts were determined for all sand samples as possible sand pollution indicators. Higher fecal indicators (both FC and FS) were obtained from the sand than from the water in most locations.

In our study area, El-Shenawy and Farag 1 investigated the spatial and temporal variability of saprophytic and water-quality bacteria along the coast of the Aqaba and Suez Gulfs and the Red Sea, Egypt, during 2002. Ibrahim and El-Shenawy 24 studied the fecal indicator bacteria and sanitary water quality along the Egyptian coasts of the Aqaba Gulf, the Suez Gulf, and the Red Sea. The results obtained by them agreed with our results and indicated that the water quality of the investigated coastal areas was generally affected by sewage disposal and (or) other anthropic influences. However, in bathing and recreational areas, the water quality was mainly affected by the excessive human presence, that is, tourists or visitors and their recreational activities. In general, the final counts of all the investigated bacterial groups were found to be in good correlation with each other.

The hydrographical parameters (temperature, salinity, dissolved oxygen, and pH) are presented in average of the annual means (Table 4). The small variations in water temperature were mostly related to seasonal conditions, and the temporal and spatial variations of other parameters were insignificant as reported by Fahmy 2,25 and Fahmy et al.26. However, in the summer months, the bacterial counts fluctuated maximally, and this may be due to the increased numbers of tourists and/or visitors in the recreational areas, leading to more human activity. Consequently, this leads to an increase in microbial pollution during the summer season. Similar results were reported in the coastal waters of Abu-Dhabi, United Arab Emirates, 18 and in the North Western Coasts of Greece 21.

Table 4

Table 4

The correlation matrix between the different investigated coastal water parameters in the different study areas is shown in Table 5. There was significant correlation between the different microbial indicators and hydrographical parameters in Aqaba Gulf . Moreover, intermediate direct correlations were shown between dissolved oxygen and each of TC, EC and FS (r=0.517, 0.523 and 0.521, P<0.05). Also intermediate direct correlations were noted between dissolved oxygen and pH values and each of TC, EC and FS (r=0.530, 0.550 and 0.550). Inverse strong correlation between temperature and each of TC, EC and FS (r=−0.773, −0.767 and −0.777,) in Suez Gulf was noted. However, in Red Sea there was a strong positive correlation between temperature and the bacterial parameters (r=0.878, 0.889 and 0.836, P<0.05). In addition, an inverse correlation between salinity and TC and EC was shown (r=−0.508 and -0.520). The same results were also noted by El Shenawy and Farag (1) and Chigbu et al. 27. They suggested that the examined bacterial parameters were the principal components affecting the coastal water quality.

Table 5

Table 5

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Conclusion

The most polluted sites were in the Suez Gulf, reaching 238 sites, followed by 194 sites of the Red Sea, whereas the Aqaba Gulf had only 108 polluted sites. Moreover, the most polluted sample locations throughout the study were Su7, Aq2, and Re15, without implementation from authorized organizations. The years in which the most polluted sites were recorded were 2000 and 2002–2004, suggesting that some corrections might have been adopted in the recent years (2008 and 2009), as they showed the lowest positive records. However, the most polluted sites were always Su7, Aq2, and Re15, without implementation of corrective actions from authorized organizations.

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Recommendations

The data of the current study must be taken into consideration by the government for safer and cleaner seawater in the eastern Egyptian coasts, especially in which critical limitations of microbial pollution are found: for example, the Ras Garib city, which always had a highly polluted coast until now. This necessitates frequent organization of workshops with the authorized bodies for dissemination of data. Accordingly, strategies should be planned based on this database for preventing such fecal pollution as detected in the contaminated spots. Moreover, sustainable development policy related to the public health point has to be established and managed integrated.

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Acknowledgements

The authors would like to thank the supports of the steering committee of the Egyptian Environmental Affair Agency (EEAA) and Danish International Development Assistance (Danida).

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Conflicts of interest

There are no conflicts of interest.

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Keywords:

Aqaba Gulf; fecal indicator bacteria; Red Sea; Suez Gulf; water quality

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