On the Distribution of Zooplankton Assemblages in Abu Qir Bay, Alexandria, Egypt

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). The average 88.7x103 and 66.1x103 ind/m3 respectively) zooplankton count amounted to 60.5x103 were observed at stations 7 and 12 and the ind/m3 for the three seasons. lowest one (average 1.7x103 ind/m3) was Regarding the spatial variations of recorded at station 3. At the other stations, zooplankton standing crop, the highest the counts were relatively high (Table 2 & average (193.5x103 ind/m3) was recorded at Fig. 4). On the other hand, the temporal station 7 and the lowest (2.5x103 ind/m3) was distribution of Protozoa indicated the highest observed at station 3 in front of El-Tabia abundance in spring (average 50.7x103 Pumping Station. Stations 12 and 14 showed ind/m3) forming 58.21% to the total relatively higher densities (average 93.7x103 zooplankton count (Fig. 3). The highest

241 ON THE DISTRIBUTION OF ZOOPLANKTON ASSEMBLAGES IN ABU QIR BAY, ALEXANDRIA, EGYPT

density in spring due to the dominance of protozoan density was observed in summer Stenosemella nivalis which flourished at (average 4.3x103 ind/m3). In winter, it was temperature between 19.50-22.85°C, salinity relatively high (average 37.9x103 ind/m3). 36.990-38.658 ppt and dissolved oxygen 3.60-5.65ml/l. Meanwhile the lowest

Table (1): Mean relative abundance of total zooplankton components (ind/m3) in Abu Qir Bay during 2004.

Taxa Mean relative abundance (ind.m3) %

Protozoa 32011 47.33

Cnidaria 7 0.01

Nematoda 33 0.05

Rotifera 1832 2.71

Annelida 1837 2.72

Cladocera 759 1.12

Ostracoda 220 0.33

Copepoda 23118 34.18

Cirripedia 124 0.18

Mollusca 7082 10.47

Echinodermata 13 0.02

Chaetognatha 24 0.04

Larvaceae 269 0.39

Fish eggs 304 0.45

Average 67633 100.00

242 HOWAIDA Y. ZAKARIA

243 ON THE DISTRIBUTION OF ZOOPLANKTON ASSEMBLAGES IN ABU QIR BAY, ALEXANDRIA, EGYPT

Table (2) cont.

244 HOWAIDA Y. ZAKARIA

Table (2) cont.

245 ON THE DISTRIBUTION OF ZOOPLANKTON ASSEMBLAGES IN ABU QIR BAY, ALEXANDRIA, EGYPT

Winter 400000 Spring Summer

Average 300000

-3 200000

ind.m

100000

St.1 St.2 St.3 St.4 St.5 St.6

St.7 St.8 St.9

St.10 St.11

Stations St.12 St.13 St.14

Fig. (2): Seasonal variations of the total zooplankton (ind/m3) in Abu Qir Bay during 2004.

100000

90000

80000 ) -3

70000

60000

50000 Zooplankton standing crop (ind.m 40000

30000

20000 Winter Spring Summer Seasons

Protozoa Copepoda Mollusca Rotifera Annelida larvae Others Fig. (3): Seasonal variations of zooplankton standing crop (ind/m3) and the frequency percentage of the most common groups in Abu Qir Bay during 2004.

246 HOWAIDA Y. ZAKARIA

250000 Winter

Spring 200000 Summe r Average

150000 -3

ind.m 100000

50000

St.1

St.2 St.3 St.4 St.5 St.6

St.7 St.8 St.9 St.10 St.11

Stations St.12 St.13

St.14

Fig. (4): Seasonal variations of the total Protoza (ind/m3) in Abu Qir Bay during 2004.

3.2.1.2. Copepoda: (1977, 1997), Nour El-Din (1987) and Abdel- Aziz (1997). In the present study, Total copepods (including their larval Clausocalanus arcuicornis Dana, Oncaea stages) ranked the second dominant group minuta Giesbrecht and Corycaeus typicus (average 16.9x103 ind/m3) contributing about Kroyer were rare species and were recorded 27.90% of the total zooplankton community. only during winter. One fresh water copepod They were represented by 11 species species, Acanthocyclops americanus March belonging to 9 genera from three orders; was recorded near El-Maadiya outlet. Calanoida (6 species), Cyclopoida (4 species) Copepoda attained their maximum density and Harpactocoida (one species) (Table 2). at station 7 (average 52.1x103 ind/m3) and Oithona nana Giesbrecht, Euterpina recorded the lowest value at station 12 acutifrons Dana and Acartia clausi (average 5.1x103 ind/m3) (Table 2 & Fig 5). Giesbrecht were the dominant copepod Stations 9, 11 and 14 showed relatively species in Abu Qir waters. These species are higher densities (average 21.6x103 , 25.3x103 among the most abundant copepod species in and 29.8x103 ind/m3 respectively) compared the neritic waters of the Mediterranean Sea to stations 1, 2 and 4 (average 8.6x103 , (Fernandez de Puelles et al., 2003 and 8.3x103 and 5.8x103 ind/m3, respectively). Siokou-Frangou et al., 2005). They were Copepods were completely absent from previously recorded as dominant species station 3 during the period of study (Fig. 5). along the Egyptian Mediterranean Coast by The temporal distribution showed a Dowidar & El-Magraby (1970), Hussein remarkable peak during summer (average

247 ON THE DISTRIBUTION OF ZOOPLANKTON ASSEMBLAGES IN ABU QIR BAY, ALEXANDRIA, EGYPT

37.1x103 ind/m3). This peak was mainly zooplankton community (Table 1). They composed of the neritic species, Oithona were represented by three marine species, nana flourished at temperature between Evaden spinifera Muller, E. tergestina and 26.00-28.50°C, salinity 37.437-38.476 ppt Podon polyphemoides Leuckart and one fresh and dissolved oxygen 3.98-6.18 ml/L. The water species, Moina micrura Kurz. As well lowest copepod density was observed in as their larval forms (ephippae larvae) were winter (average 2.2x103 ind/m3). The present. population density during spring was The highest density was recorded at 11.4x103 ind/m3. station 9(average 434 ind/m3) while other stations harboured very low counts (Table 2). 3.2.1.3. Rotifera: One peak was observed during spring (average 303 ind/m3). Numerically, rotifers were rather frequent contributing about 3.81% (average 2306 3.2.1.4.2. Larvaceae: ind/m3) to the total zooplankton count. They were represented by 14 species belonging to The average count of Larvaceae 6 genera. Among them, Synchaeta pectinata amounted to 147 ind/m3 contributing about Ehrenberg, S. oblonga Ehrenberg and S. 0.24% to the total zooplankton crop (Table tremula O. F. Muller were the most dominant 1). They were represented by 3 species species and constituted 56.60% of the total belonging to two genera. The most dominant Rotifera population. These species were also species was Oikopleura dioica Fol. while dominant in the Eastern Hrbour of Fritillaria borealis Lohm. rarely occurred in Alexandria (Zakaria, 2006). Abu Qir waters. The average density of Concerning the spatial distribution, Larvaceae ranged between 373 ind/m3 at rotifers showed highest density (average 5826 station 7 to 69 ind/m3 at station 2 (Table 2). ind/m3) at station 5 (in front of El-Maadiya Larvaceae was not recorded at stations 1, 3, outlet) and the lowest at station 3 (average 4, 5 and 6 during the whole period of study. 210 ind/m3). Stations 2, 4, 6 and 12 attained A pronounced peak was observed during relatively higher densities (4601, 4176, 4363 summer (average 256 ind/m3) while the and 4287 ind/m3 respectively) compared to lowest count was recorded in winter (average other stations in the study area (Table 2 & 3 ind/m3). Fig. 6). The highest count of rotifers was recorded 3.2.1.4.3. Ostracoda: during winter (average 3854 ind/m3), then the density decreased in spring to 1620 ind/m3 Ostracod shells and nauplii reached to 120 and reached its minimum value (average ind/m3 constituting 0.20% of the total 1444 ind/m3) during summer. zooplankton crop (Table 1). They were represented by only one species, Cypridina 3.2.1.4. Other holoplanktonic groups: mediterranea Costa. The highest density occurred at station 1 (687 ind/m3) and the 3.2.1.4.1. Cladocera: lowest at station 13 (16 ind/m3). Ostracods were more abundant during winter and spring The cladocerans (average 159 ind/m3) (average 136 and 177 ind/m3, respectively). contributed about 0.26% to the total

248 HOWAIDA Y. ZAKARIA

120000 Winter Spring 100000 Summe r Average 80000

-3 60000

ind.m 40000

20000

St.1 St.2 St.3 St.4 St.5

St.6 St.7 St.8 St.9 St.10 St.11 St.12

Stations St.13

St.14

Fig. (5): Seasonal variations of the total Copepoda (ind/m3) in Abu Qir Bay during 2004.

12000 Winter

Spring 10000 Summe r 8000 Average

-3 6000

ind.m 4000

2000

St.1 St.2

St.3 St.4 St.5 St.6 St.7

St.8 St.9 St.10

St.11 St.12

Stations St.13 St.14

Fig. (6): Seasonal variations of the total Rotifera (ind/m3) in Abu Qir Bay during 2004.

249 ON THE DISTRIBUTION OF ZOOPLANKTON ASSEMBLAGES IN ABU QIR BAY, ALEXANDRIA, EGYPT

3.2.1.4.4. Nematoda: trochophore larvae of polychaetes. They amounted together to an average of 2308 Free living nematods (average 33 ind/m3) ind/m3 forming 3.82% of the total contributed about 0.05% to the total zooplankton community. zooplankton crop. They were recorded only Annelida larvae attained their maximum at stations 1, 2, 3 and 4 with average density density (average 7982 ind/m3) at station 1 of 63, 129, 252 and 18 ind/m3, respectively. (near Abu Qir head) (Table 2 & Fig. 8). This highest density was due to the great numbers 3.2.1.4.5. Chaetognatha: of spinoid larvae of polychaetes which flourished at water salinity 35.737-38.611ppt. Chaetognatha amounted to 24 ind/m3 The lowest count was recorded at station 11 constituting 0.04% of the total zooplankton. (average 198 ind/m3). Seasonal abundance of They were represented by Sagitta sp. The annelid larvae attained one peak during highest density occurred at station 7 (105 winter (average 4022 ind/m3) but the lowest ind/m3) and the lowest occurred at station 13 count occurred in spring (average 1384 (19 ind/m3). They were abundant during ind/m3). In summer, the population density summer (average 41 ind/m3). was 1519 ind/m3.

3.2.1.4.5. 1. The meroplanktonic groups: 3.2.1.4.5. 1. 3. Fish eggs:

3.2.1.4.5. 1. 1. Mollusca: During the present study, fish eggs counted an average of 114 ind/m3 forming Lamellibranch and gastropod veligers about 0.19% of the total zooplankton crop. formed about 12.10% with an average density They were more abundant during winter and of 7315 ind/m3 (Table 1). They attained spring (average 303 and 39 ind/m3 higher count than that recorded in the Eastern respectively). Harbour (average 2483 ind/m3 representing 5.81% of the total zooplankton stock) by 3.2.1.4.5. 1. 4. Cirripedes: Zakaria (2006). In the present study, they showed maximum density at station 7 Cirriped nauplii and cypris larvae formed (average 44.458x103 ind/m3) and the lowest at 0.17% of the total zooplankton (average 99 station 9 (449 ind/m3) (Table 2). They were ind/m3) (Table 1). The highest density was completely absent from station 3 during the recorded at station 1 (average 502 ind/m3) period of study (Fig. 7). A remarkable peak and the lowest value appeared at station 9 was observed during spring (average (average 24 ind/m3).The highest count of 19.749x103 ind/m3). cirripeds was recorded during winter (average 271 ind/m3). 3.2.1.4.5. 1. 2. Annelida: 3.2.1.4.5. 1. 5. Echinoderms: Annelida was represented in zooplankton hauls by the larval forms of 3 species; Echinoderm larvae were rare amounting Megelona papillicornis Muller, Nereis to13 ind/m3 (0.02%) (Table 1). They belong pelagica Linnaeus and Polydora ciliata to Ophiuroidea and Echinoidea. They were Johnston in addition to spinoid and more abundant during spring (29 ind/m3).

250 HOWAIDA Y. ZAKARIA

140000

Winter

120000 Spring Summer 100000 Average

-3 80000

ind.m 60000

40000

20000

St.1 St.2 St.3 St.4 St.5

St.6 St.7 St.8 St.9 St.10 St.11

Stations St.12 St.13

St.14

Fig. (7): Seasonal variations of the total Mollusca (ind/m3) in Abu Qir Bay during 2004.

25000 Winter Spring 20000 Summe r Average 15000 -3

ind.m 10000

5000

St.1 St.2

St.3 St.4 St.5 St.6 St.7 St.8

St.9 St.10 St.11

Stations St.12 St.13 St.14

Fig. (8): Seasonal variations of the total Annelida (ind/m3) in Abu Qir Bay during 2004.

251 ON THE DISTRIBUTION OF ZOOPLANKTON ASSEMBLAGES IN ABU QIR BAY, ALEXANDRIA, EGYPT

3.2.1.4.5. 1. 6. Cnidaria: station in Abu Qir Bay. It fluctuated between 1.71 and 2.45 with an average of 2.01. The This group was very rare and was relatively higher values (2.41 and 2.45) were represented by the medusa of one species, observed at stations 5 and 6 respectively (Fig. Obelia sp. with an average count of 7 ind/m3 9). The lowest diversity index (1.71) occurred (Table 1). at station 7 which harboured the greatest Shannon and Weaver diversity index of zooplankton crop in the study area (Fig.9). the zooplankton taxa differed from station to

Standing Crop Diversity 200000 2.50

150000 2.30 )

-3

100000 2.10

Diversity

(ind.m Standing crop 50000 1.90

0 1.70

St. 1 St. 2 St. 3 St. 4 St. 5 St. 6 St. 7 St. 8 St. 9 St.

10St. 11St. 12St. 13St. 14St. Stations

Fig (9): Standing crop (ind/m3) and diversity index recorded at different stations of Abu Qir Bay during 2004.

252 HOWAIDA Y. ZAKARIA

4. DISCUSSION frequency percentage of Copepoda was recorded during winter (4.31%), increased to The zooplankton standing crop in Abu Qir 13.09% during spring and reached its Bay indicated a highly productive area with maximum value (83.62%) during summer. an average of 60.474x103 ind/m3. The long- The trend of distribution of both groups was term observations of zooplankton standing closely correlated with salinity variations in crop in Abu Qir Bay revealed remarkable the bay where Copepoda tend to be more variations throughout the last 42 years. abundant with higher salinity values while During 1962, before the construction of Protozoa tend to be abundant with lower Aswan High Dam, the standing crop in Abu values. The same trend of seasonal Qir Bay was 22.4x103 ind/m3 (El-Maghraby distribution of both groups was previously & Dowidar,1973). It decreased to 13.69x103 recorded in the Eastern Harbour of ind/m3 during 1974 (Dowidar et al, 1983). Alexandria by Zakaria (2006). Regarding the other coastal areas of Meroplanktonic Mollusca was more abundant Alexandria, the standing crop in Abu Qir Bay in Abu Qir Bay during spring where the was much greater than that previously temperature and salinity values were the recorded in El-Mex Bay (25.078x103 ind/m3) optimum for the growth and breeding of by Hussein (1997) and in the Eastern Harbour many invertebrates. of Alexandria (42.728x103 ind/m3) by Zakaria The zooplankton community in Abu Qir (2006). Bay was affected significantly by waste water The zooplankton organisms recorded in from TPS and the fresh water from Idku Lake Abu Qir waters are living under a range of through El-Maadiya outlet. The south water temperature 16.1-28.5°C and water western part of Abu Qir Bay attained an salinity 34.807–38.658 ppt. The highest average zooplankton density of 43.454×103 seasonal abundance of total zooplankton ind/m3. This reflects the effect of brackish (average 87.057x103 ind/m3) was observed water from Idku Lake through El-Maadiya during spring (April) where the water outlet and the waste water from TPS. The temperature was between 19.50 and 22.85°C average zooplankton count recorded in the and the water salinity was between 36.990 present study was higher than that previously and 38.658 ppt. Such peak was caused by the recorded in the same area during 1974 (5- great numbers of protozoans, veligers of 20×103 ind/m3) by Dowidar et al (1983) and molluscs and copepods. On the other hand, less than that recorded during 1998-99 summer (June) harboured the lowest counts (90.075×103 ind/m3) by Abdel-Aziz (2001). (44.226×103 ind/m3). The spatial distribution of zooplankton The zooplankton community in Abu Qir standing stock in Abu Qir Bay indicated that, waters was dominated by protozoans, the highest zooplankton density recorded at copepods and veligers of molluscs station 7 (average 193.483x103 ind/m3) was constituting 51.19%, 27.90% and 12.10% of accompanied with water salinity 37.854- the total zooplankton crop respectively. The 38.425 ppt and dissolved oxygen 3.90-4.83 seasonal variations of the most common mgO2/l. It was mainly due to flourishing of zooplankton groups in Abu Qir Bay indicated protozoans, copepods and veligers of that, the percentage frequency of Protozoa molluscs. Meanwhile the lowest density reached its maximum value (75.68% of the (average 2.516x103 ind/m3) at station 3 which total zooplankton crop) during winter. This was directly affected by wastes discharged value decreased during spring to 58.21% and from El-Tabia pumping station. The waste reached its minimum (9.38%) during water in the vicinity of TPS is warmer than summer. On the other hand, the lowest the bay water. The increase in temperature

253 ON THE DISTRIBUTION OF ZOOPLANKTON ASSEMBLAGES IN ABU QIR BAY, ALEXANDRIA, EGYPT

reaches about 1°C higher than the average of the research plan for his helpful water temperature in summer and 1.12°C in cooperation. spring. This waste water in all seasons is characterized by lower values of salinity and REFERENCES dissolved oxygen. The salinity values varied between 34.807 and 36.99 ppt throughout the Abdel-Aziz, N. E.: 1997, Zooplankton study period. Lowest value of dissolved production along Egyptian Medirerranean oxygen (0.30 mgO2/l) was observed during coast at Alexandria with special reference summer. It increases to 1.6 mgO2/l in spring to life history of one copepod species. Ph. and reaches the maximum value (3.05 D. Thesis, Faculty of Science, Mansoura mgO2/l) in winter. This high oxygen content University, 384p. in the bay water is explained as a result of Abdel-Aziz, N. E.: 2000, Weekly strong wind and wave action during the observations on zooplankton community winter months. The impact of these in a sea-lake connection (Boughaz El- environmental parameters is clearly observed Maadiya), Egypt. Bull. Fac. Sci., Alex. on the zooplankton community at this station Univ., 40 (1,2): 68-83. which is composed of fresh water ciliates, Abdel-Aziz, N. E.: 2001, Zooplankton rotifers, free living nematods as well as community under the stress of polluted polychaete larvae. In this station, Protozoa land-based effluents in Abu Qir Bay, was represented only by Tintinnopsis Alexandria, Egypt. Bull. Fac. Sci., Alex. beroidea, T. campanula, Paramecium sp. and Univ., 41 (1,2): 57-73. Quinqueloculina sp. Rotifera was represented Abdel-Aziz, N. E., & Dorgham M. M.: 1999, by Keratella quadrata and K. tropica. The Ecological characteristics of plankton in Keratella species has been indicated as an brackish water, Egypt. Egypt. J. Aquat. indicator of pollution (Sampath et al., 1978 Biol. & Fish., 3 (4): 215-242. and Bahura et al., 1993). Other zooplankton Bahura, C.K., Bahura P. & Saxena M. M.: groups completely disappeared. 1993, Zooplankton community of Shannon and Weaver diversity index Shivbari temple tank, Bikaner, J. Ecol, 5: revealed that Abu Qir Bay has a great variety 5-8. of species (high diversity). The highest Dowidar,N. M. & El-Maghraby A.M.: 1970, diversity values, 2.41 and 2.45 were observed The neritic zooplankton of the south at stations 5 and 6 close to El-Maadiya outlet. eastern Mediterranean at Alexandria. I- These stations harboured the most diversified Distribution and ecology of the community than the other stations due to the zooplankton organisms with special contribution of fresh water species coming reference to Copepoda. Bull. Nat. Inst. from Idku Lake. This is in agreement with the Oceanogr.& Fish., ARE, 1: 225-273. records of Abdel-Aziz (2000 and 2001). Dowidar, N. M. & El-Maghraby A. M.: 1971, Observations on the neritic zooplankton ACKNOWLEDGEMENT community in Abu Qir Bay during the flood season. Rapp. Comm. Int. Mer The present investigation is a part of the Medit., 20(3): 385-389. research plan of Marine Environment Dowidar, N. M.; Gerges M., El-Samra M. I. Division of the National Institute of & El-Deeb M.K.: 1983, General review of Oceanography and Fisheries entitled ”Effect the ecological conditions of Abu Qir Bay. of land based sources on physical, chemical Unesco reports in marine sciences, and biological characteristics of Abu Qir Bay 20:124-133. waters”. The author is indebted to Prof. Edmondson, W.T.; Ward H.B. & Whipple Mamdouh Abbas, the principal investigator G.C.: 1959, Fresh water biology, 2nd ed.

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