Distribution of macrobenthic fauna in the area investigated
Distribution of M.B.I. in different sampling sectors in the main
channel of Lake Nasser showed remarkable changes from one
sector to another. The highest P.D. (1848 organisms/m2) was
recorded in Tushka during spring and the lowest P.D.
(36 organisms/m2) was recorded in Dahmit during summer.
M.B.I. disappeared totally in Wady Abyad during summer
and in Up Stream during autumn (Table 4). The highest annual
average of P.D. (1132 organisms/m2) was recorded in sector
Tushka, while the lowest one (127 organisms/m2) was recorded
Table 2 Species recorded in the main channel of Lake Nasser during this study.
Species recorded Up-Stream Dahmit Kalabsha Wadi-Abyad El-Madiq Korosko Amada Tushka Abu-Simble Adindan Average
Annelida 55 86 127.5 144 36 486 297 754 323 144 2452
Limnodrilus udekemianus 45 36 9 99 24 279 117 371 165 84 1229
Limnodrilus hoffmeisteri 5 32 93 31 12 108 108 219 95 60 763
Branchiura sowerbyi 5 18 16 0 0 60 33 52 54 0 238
Pristina sp. 0 0 3 13 0 39 39 80 9 0 183
Helobdella conifera 0 0 6 0 0 0 0 33 0 0 39
Mollusca 109 41 175 9 49 165 114 117 93 72 943
Valvata nilotica 72 23 114 9 49 102 111 107 57 24 667
Melanoides tuberculata 4 0 24 0 0 9 3 0 18 36 94
Cleopatra bulimoides 0 14 0 0 0 0 0 0 0 12 26
Bulinus truncatus 23 0 13 0 0 0 0 0 18 0 54
Physa acuta 0 0 11 0 0 0 0 0 0 0 11
Gyraulus ehrenbergi 9 0 9 0 0 0 0 0 0 0 18
Corbicula consobrina 0 4 5 0 0 0 0 0 0 0 9
Spharium simile 0 0 0 0 0 15 0 0 0 0 15
Pisidium pirothi 0 0 0 0 0 39 0 11 0 0 50
Arthropoda 32 4 3 50 42 216 358 261 150 384 1500
Chlamidothica unispinosa 0 5 0 0 0 0 18 25 27 0 75
Pupa of Chironomidae 0 0 0 14 0 30 21 0 0 0 65
Chironomus sp. 14 0 0 18 30 75 229 93 44 132 635
Polypedilum sp. 14 0 0 18 0 3 18 60 3 132 248
Tanytarsus sp. 5 0 3 0 0 72 51 76 36 72 315
Cryptochironomus spp. 0 0 0 0 0 36 9 3 0 36 84
Perithemis sp. 0 0 0 0 12 0 6 3 9 12 42
Ischnura sp. 0 0 0 0 0 0 6 0 13 0 19
Trichoptera larvae 0 0 0 0 0 0 0 0 9 0 9
Hydrovatus sp. 0 0 0 0 0 0 0 0 9 0 9
Total number of individuals 194 131 306 203 127 867 769 1132 566 600 4895
Table 3 Number of species, diversity index, evenness, dominance percentages and species richness in different sectors.
Up-Stream Dahmit Kalabsha Wadi-Abyad El-Madiq Korosko Amada Tushka Abu-Simble Adindan
Number of