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The Biology of Four Haplochromine Species of Lake Kivu (Zaire) with Evolutionary Implications

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The Biology of Four Haplochromine Species of Lake Kivu (Zaire) with Evolutionary Implications The Biology of Four Haplochromine Species of Lake Kivu (Zaire) with Evolutionary Implications by Michele Losseau-Hoebeke Thesis Submitted in fulfilment of tbe requirements for !be Degree of Master of Science Department of Ichtbyology and Fisheries Science Rhodes University Grabamstown Soutb Africa January 1992 "La pensee est un oiseau de l'espace, qui dans une cage de mots peut ouvrir ses ailes mais ne peut voler." (Khalil Gibran, 1923) 1 Table of Contents page List of figures List of tables Acknowledgements Abstract I. Introduction 1 II. Lake Kivu 4 1. Introduction 4 2. Geological history 5 3. Limnology 10 4. Biotopes and their associated faunas 13 III. Study Area: Tsbegera Island 18 1. Introduction 18 2. Physiographic features 19 3. Related faunas 21 IV. Taxonomy 22 1. Introduction 22 2. Characters used in species' identification 23 3. Diagnostic features of the species studied ................. ,, ' . .. .. .. 25 Haplochromis astaJ<Hion a. Taxonomy ..... .... ... ... .... ... .. .......... .. .. 26 h. Species' identification . • . 26 c. Relation between form and function ........ ..... •. ... ...,. 29 d. Phyletic classification . • . 30 Haplochromis olivaceus and Haplochromis crebridens a. Taxonomy ........ ....... • ......... ........ • .... 31 h. Species' identification . 31 c. Relation between form and function . 37 d. Phyletic classification .............. ... • ..... .. ..... .. 38 Haplochromis paucUkns a. Taxonomy ..................... ... .... .. ... ... .. .. 39 h. Species' identification . 39 c. Relation between form and function .. 43 d. Phyletic classification . • . 43 I 11 I V . Breeding Biology 44 I \. Introduction 44 I I 2. Material and methods 45 I a. Monthly sampling .................................. 45 b. Reproductive seasonality .............................. 46 c. Fecundity . ... ....... .. .... .. .. ... • •.. .. .. 46 d. Condition factor ............................•....... 47 3. Results 48 I a. Monthly sampling .................................... 48 b. Reproductive seasonality .•....... ............ •.... .... 51 c. Fecundity ...... ... ... ... ................••. .. .. 53 d. Condition factor •. ..... .. ..... .• .•••..•. ......... 55 4. Discussion 60 VI. Circadian Activity and Fish Distrib"lltion ..................... 64 \. Introduction 64 2. Material and methods 65 a. Circadian activity ... ... •..• ...........•...•......... • 65 b. Activity peak analysis . 66 3. Results 67 a. Circadian activity ...........................•........ 67 b. Activity peak analysis . • • . • • • . 71 4. Discussion 73 VII. General Discussion 75 \. Taxonomical and ecological aspects 75 2. Evolutionary implications 80 a. Mode of speciation in the African Great Lakes ....... 80 b. Evolutionary status of Lake Kivu ... ... ....... ..... ...• ..... 82 c. Conclusion . • . • . 83 3. Vulnerability of Lake Kivu 84 VIII. Bibliography 86 Appendix A. Fish diversity in Lake Kivu. B. Geological time scale and adaptive nldiation of cichlids in African Great Lakes. C. Bathometric map of Lake Kivu. D. Agenda of sampling events. E. Breeding territory distribution of the species studied. \. Description 2. Illustration iii List of Figures Figure I: Location of Lake Kivu and the study site, Tshegera Island (from Reeky and Degen" 1973) ... .... .. ..... ............ ... ... .. ..... Figure 2: View on the latest eruption in June 1989 when a vent of the Nyamulagira exploded .... 4 j Figure 3: A north-south profile of the Central African Rift (from Pouc1et, 1978) . ... ... 5 Figure 4: Changes in geology and hydrology of the Western Rift VaHey between Lake EdW8'U and Lake Tanganyika from the late Pleistocene onwards ................. 6 Figure 5: Reconstruction of the lake level in Kivu for the last 15 000 years (from Reeky aoJ Degens, 1973). ................ ..... .. ................. 8 Figure 6: The lava flow from the Nyamulagira volcano (1938-1940) almost cut the Basin of Kabunu from the Main Basin. .... ... ....... ..... ...... .. ... .. .. .. • 9 Figure 7: Average values of temperature, conductivity and density obtained from 23 vertical profil,", in the Main Basin (from Tietze, 1981) . .. ... .. .. ..... ... ...... 10 , Figure 8: Variation in transparency and in the quantity of zoop1anktnn over a one year period in Lake Kivu (from Verbeke, 1957a.) .. .. .... ......... .. .. ...... ... 11 i Figure 9: Dissolved oxygen profJ.!e of Lake Kivu (from Damas, 1931). ..• . ... ... .. ' 12 Figure 10: A theoretical transect through the macrophytic environment along the sandy tn muddy ! shoreline of Lake Kivu (from Van der Ben, 1959). .... .. .... .. .... ...• IS f Figure 11: Tbsegexa Island situated along the north-west coast of Lake Kivu. .. .... ' 18 ; Figure 12: Bathometric and bottnm type maps of the coastal zone at Tbsegexa Island. ..... 19 Figure 13: Characteristics of body and head shape used tn differentiate the various species. 23 Figure 14: The three basic types of tnoth observed in the haplochromines and tnoth nomenclatu'" (from Barel et aI.,1971) . • . 24 Figure IS: Shape of the tooth band illustxating the position of the outer and inner rows of teelh (from Barel et aI., 1917). ... ... ...... 24 Figure 16: Sexually mature male and female H. astatodon. •.... ...•. ..... • .. , 26 Figure 17: Head shape of female and male H. ast<JIodon. • . • . , 27 Figure 18: Outer tnoth description of H. astatodon. 27 Figure 19: Colours displayed in the dorsal, caudal and anal fins of dominant H. astatodon males. 28 Figure 20: Classification of H. astatodon within the genus 'Haplochromis' (Greenwood, 1979).. 30 Figure 21: SexuaHy mature male and female H. olivaceus. 31 iv Figure 22: Head shape of female and male H. olivaceus . ....•.......... ... ... 32 Figure 23 : Outer tooth description of H. olivaceus. .......... ...... .. ... ... 32 Figure 24: Colours displayed in the dorsal, caudal and anal fins of dominant H. olivaceus males. 33 Figure 25: Sexually mature males and female H. crebridens. 34 Figure 26: Head shape of female and male H. crebridens. .......... ........•... 35 Figure 27: Outer tooth description of H. crebridens comparatively to H. olivaceus . ....... 35 Figure 28: Colours displayed in the dorsal, caudal and anal fins 'of dominant H. crebridens males .. 36 Figure 29: Classification of H. olivaceus and H. crebridens within the genus 'Xystochromis' (Greenwood, 1979). .... .. ................. ... .......... , 38 Figure 30: Mature male and females H. paucidens. ...... ... .. ... ... ...... .... 39 Figure 31 : Head shape of male and female H. paucidLns. .. .. ... .. ... .... 40 Figure 32: Outer tooth description of H. paucidens . ................... ... ... .. 40 , Figure 33: Colours displayed in the dorsal, caudal and anal fins of dominant H. paucidLns males.. 41 Figure 34: Two dominant H. paucidens males chasing each other. ....... ....... 42 t Figure 35: Classification of H. paucidLns within the genus 'ParaIabidochromis' (Greenwood, 1980) .... ......... ...... .. ........................ 43 Figure 36: A male H. paucidLns nudging its partner. ........................ 44 I, Figure 37: Two nets set parallel to the coastline in front of the vegetated zone at Tshegera Island .. 45 , Figure 38: The reproductive stages during the female gonadal development. .. ...•... .. 46 ! Figure 39: Multiple box and whisker plot. 47 Figure 40: Total number of the four species caught in January and February 1988 during net I selectivity trials ....... .... ... .. ............... .. ......... 48 Figure 41: Number of males and females caught per month. 49 Figure 42: Size distribution of both sexes combined for the total catches. so Figure 43: Perrentage of males and females caught in 5 rnm size classes. 51 Figure 44: Percentage of resting and developing, breeding and spent females per month, and mean GSI per month. ... .. ........ ... .. ... ........ .. ........ 52 Figure 45 : Relationship between standard length against fecundity. • . 54 Figure 46: Length - weight relationship of males and females separately. 55 Figure 47: Relationship between standard length and condition factor for females and males separately.. 57 • •~ v , II Figure 48: Relationship between time and condition factor for females and males separately. 58 ~. Figure 49: Relationship between gonad maturation stages in the females and condition factor. .. 59 ~ Figure 50: Fishing sites during the first, second and third 24-hour cycles at Tsbegera. 64 r Figure 51: Net sequence and position during the first, second and third 24-hour cycle at Tshegera Island. 65 t Figure 52: Percentage of the species studied caught in each mesh size during the first and second , 24-hour cycles. ... ... ............ ........ .. ... ... ... .. 67 , Figure 53: Number of the 'species studied', 'other haplochromines' and 'non-haplochromines' caught per four-hour fishing period during the first, second and third 24-hour cycles.. 68 Figure 54: Number of the species studied caught per four-hour fishing periods during the first and I second 24-hour cycles in top and hottom set nets. ... .. ... .... .... ..... 69 Figure 55: Percentage of the species studied relative tn the tnta! haplochromine catch and relative tn one anotherfor every 24-hour cycle. .... ...........•.. ..... .. .. .. 70 Figure 56: Percentage composition of the species studied in the early morning and evening along the vegetated aod rocky zones. ... .... ...... ..... ... ... .. .. .. .... 71 Figure 57: Analysis of the activity of the species studied in relation tn change in light intensity in the early morning and evening along vegetated and rocky zones. ............
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