on the distribution of zooplankton assemblaces in abu-qir bay, alexandria, egypt Item Type Journal Contribution Authors Zakaria, H.Y. Citation Egyptian journal of aquatic research, 33(1). p. 238-256 Publisher National Institute of Oceanography and Fisheries, Egypt Download date 27/09/2021 21:47:10 Link to Item http://hdl.handle.net/1834/1900 EGYPTIAN JOURNAL OF AQUATIC RESEARCH ISSN: 1687-4285 VOL. 33 NO. 1, 2007: 238-256 ON THE DISTRIBUTION OF ZOOPLANKTON ASSEMBLAGES IN ABU QIR BAY, ALEXANDRIA, EGYPT HOWAIDA Y. ZAKARIA National Institute of Oceanography & Fisheries [email protected] Keywords: Zooplankton, Coastal waters, Abu Qir Bay, Egypt. ABSTRACT Abu Qir Bay is a shallow semi-circular basin lying 35 Km east of Alexandria city. The bay is facing the problem of pollution which discharged into the bay from different sources; El-Tabia Pumping Station (TPS), the outlet of Idku Lake and the Rosetta mouth of the Nile River. Quantitative and qualitative studies of zooplankton community in Abu Qir Bay were performed seasonally during 2004. Fourteen stations were selected to represent the different habitats in the bay.The seasonal variations of zooplankton standing stock in Abu Qir Bay indicated that, the highest count (average 87.1x103 ind/m3) occurred during spring, while the lowest (average 44.2x103 ind/m3) was recorded in summer. The average zooplankton count during the period of study amounted to 60.5x103 ind/m3. The minimum zooplankton crop (average 2.5x103 ind/m3) in front of El-Tabia Pumping Station reflects the effect of wastes discharged into the bay. The zooplankton assemblages in Abu Qir Bay were dominated by Protozoa, Copepoda and meroplanktonic Mollusca which contributed 51.19%, 27.90% and 12.10% respectively to the total zooplankton count. A total of 85 zooplankton species were identified during the period of investigation. The zooplankton organisms recorded in Abu Qir Bay live under a range of water temperature 16.1-28.5oC and water salinity 34.807–38.658 ppt. 18 species (i.e. 22.35% of the species recorded) are euryhaline species. 1. INTRODUCTION (TPS), the outlet of Idku Lake and the Rosetta mouth of the Nile River. Abu Qir Bay is a shallow semi-circular The estimated amount of untreated basin lying 35 Km east of Alexandria city. sewage and industrial wastes from 22 The bay has a shoreline of about 50 Km long different factories pumped to Abu Qir Bay and the maximum depth of about 16 m. The through TPS is of about 2 millions m3/day. surface area of the bay is about 360 Km2 and The exchange of water between Abu Qir Bay the water volume is 4.3 Km3 (Said et al., and Idku Lake occurring through El- 1995). The bay was considered as a fertile Maaddiya channel (about 100 m long, 20 m marine habitat when compared with the other wide and 3 m deep) is controlled by the Egyptian Mediterranean coastal waters. As in prevailing wind and the difference in water many coastal regions near major urban areas, level between the bay and the lake. Actually, the bay is used for variety of purposes; the amount of brackish water discharged commercial fishing, shipping, recreational from the lake to the bay is at a rate of about boating, swimming and as a repository for 3.3 million m3/day (Report on pollution status sewage effluents. During the last three of Abu Qir Bay, 1984). The Nile River, decades, the bay is facing the problem of although its discharge has been considerably pollution which discharges into the bay from decreased since 1965, now controlled by different sources; El-Tabia Pumping Station Aswan High Dam, is still the main HOWAIDA Y. ZAKARIA discharging source into the south eastern Two replicates of 2 ml were transferred into a Mediterranean. From 1965 on, the discharge counting cell and each zooplankter was of the Nile River, measured at Edfina (30 Km identified and counted under a binocular south of Rosetta outlet), indicated that, the research microscope. The identification of average annual discharge is still about 3.76 zooplankton organisms was done according km3. to Rose (1933), Tregouboff & Rose (1957) Many oceanographic studies related to and Edmondson et al. (1959). The standing physical, chemical, geological and biological crop of total zooplankton community was aspects of marine pollution have been carried calculated and expressed in number per cubic out in Abu Qir by many authors. Zooplankton meter. community was studied based on one Species diversity was calculated collection (Dowidar & El-Maghraby, 1971; according to Shannon and Weaver equation El-Maghraby & Dowidar,1973), one station (1963). sampling in front of Boughaz El- Maadiya n (Gharib and Soliman, 1998; Abdel-Aziz, 2000 and Abdel-Aziz and Dorgham, 1999) or H = ∑ pi ln pi on seasonal sampling (Dowidar et al, 1983). i=1 Zooplankton distribution and community Where: pi = n/N is the proportion of the structure were studied monthly from April number of individuals of species (n) to the 1998 to March 1999 in the south western part total number of individuals (N). of Abu Qir Bay, which is the most polluted area in the Bay by Abdel-Aziz (2001). 3. RESULTS Since 1999, no studies were carried out on zooplankton community in Abu Qir Bay. 3.1. Physico-chemical characteristics of Thus, the present work is aimed to study the Abu Qir Bay waters: zooplankton assemblages and their distribution in relation to the impact of waste The seasonal variations of the surface discharge in Abu-Qir Bay. water temperature of Abu Qir Bay are very closely related to those of the air temperature. 2. MATERIALS AND METHODS In February (winter), the lowest values of air temperature were observed, the surface water Quantitative and qualitative investigation temperature varied from 16.1°C to 18.3°C. A of zooplankton community in Abu Qir Bay steady rise of air temperature over the bay were performed during three seasons of 2004 normally started in March and consequently namely winter (February), spring (April) and the surface water temperature increased. In summer (June). Fourteen stations were April (spring), the water temperature selected to represent the different habitats in increased westward from 19.5°C in the open the bay. Fig. (1) illustrates the study area and sea to 22.85°C near El-Tabia pumping station locations of the sampling stations. (TPS). During June (summer), the air Zooplankton samples were collected at temperature reached its maximum value each station by vertical hauls (from bottom to throughout the year. In summer, the surface the surface) using standard plankton net of 55 water temperature varied between 26.00 and µm mesh. The collected samples were 28.50°C. preserved in 4% neutral formalin solution and their volumes were concentrated to 100ml. 239 ON THE DISTRIBUTION OF ZOOPLANKTON ASSEMBLAGES IN ABU QIR BAY, ALEXANDRIA, EGYPT Fig. (1): Abu Qir Bay area and locations of the sampling stations 240 HOWAIDA Y. ZAKARIA Salinity in Abu Qir Bay varied regionally and 76.6x103 ind/m3 respectively) compared within a wide range. In winter, the minimum to the other stations of the study area (Table 2 salinity 34.807ppt was observed at TPS. Due & Fig.2). to the influence of the brackish water The seasonal variations of zooplankton discharge from Lake Idku through El- standing stock in Abu Qir waters indicated Maadiya outlet and the waste water from that, the highest count (average 87.1x103 TPS, the salinity values of less than 37.00ppt ind/m3) occurred during spring while the were found in the western part of Abu Qir lowest (average 44.2x103 ind/m3) was Bay. In spring, due to a decrease in the recorded in summer (Fig 3). During winter, amount of fresh water discharged from the the standing crop attained 50.1x103 ind/m3. river as compared to winter months, the surface salinity increased from 36.990 to 3.2.1. The holoplanktonic groups: 38.658ppt. The effect of the brackish water from Lake Idku and the waste water from 3.2.1.1. Protozoa: TPS on the salinity distribution in the bay was clearly observed during the summer Protozoa contributed about 51.19% of the months. During summer, the surface salinity total zooplankton community with an average varied between 35.364 and 38.476ppt. of 30.96x103 ind/m3. They were represented During winter, the dissolved oxygen by 47 species belonging to 23 genera from ranged from 3.05 mgO2/L at TPS to 5.93 five orders: Tintinnidae (41 species), Ciliata mgO2/l in the open sea. In spring, the (one species), Rhizopoda (one species), dissolved oxygen increased from 1.60 Radiolaria (one species) and Foraminifera (3 mgO2/L at TPS to 5.65 mgO2/L in the open species). sea. During summer, the oxygen content Stenosemella nivalis (Meunier), (0.30 mgO2/L) near TPS reached its Tintinnopsis campanula (Ehrbg.) and Favella minimum values throughout the year. It ehrenbergi (Claparede & Lachmann) were increased seaward to reach 6.18 mgO2/L. the most dominant Protozoa species in Abu Qir waters, forming 41.53%, 17.18% and 3.2. Zooplankton assemblages in Abu Qir 7.14% respectively of the total Protozoa Bay: population. The frequent Protozoa species included Tintinnopsis beroidea (St.), The zooplankton assemblages in Abu Qir Eutintinnus fraknoi (Daday) and Favella waters were dominated by Protozoa, markuzowskii (Daday) (Table 2). Two fresh Copepoda and meroplanktonic Mollusca water protozoans, Paramicium sp. and which contributed 51.19%, 27.90% and Quinquoloculina sp. were recorded near El- 12.10% respectively to the total zooplankton Tabia pumping station and El-Maadiya outlet crop (Table 1). A total of 85 zooplankton during winter. species were identified during the period of The highest Protozoa densities (average investigation (Table 2).