QH 1 EllX NH JOURNAL OF THE EAST AFRfCA NATURAL HISTORY SOCIETY ANO NATIONAL MUSEUM urn rtUGUST 1979 NOTE ON LITTORAL ALGAE FROM MOMBASA, KENYA Jon Knutzen Norwegian Institute for Water Research^ P.O. Box 333, Blindern, Oslo, 3 Norway and Erik Jaasund Institute for Biology and Geology, University of Tromsd, 9001 Tromsd, Norway INTRODUCTION Published records of benthic algae from the Kenya coast are rather scarce (Gerloff 1960; Taylor 1966, Isaac 1967, 1968 and 1971; Moorjani 1969, 1970). From the Mombasa area there are a few reports (Taylor 1966, Isaac 1971). A field guide to the intertidal seaweed communities of East Africa has recently been published (Jaasund 1976), the nomenclature of which is used here. (See also Jaasund 1977 a, b, c.). Observations were made September-October 1974 and 1975 as part of a water pollution and waste disposal study for the municipality of Mombasa, conducted by Norconsult A/S for the Kenya Ministry of Local Government. The intention was to find out if there were any symptoms of pollution and to obtain a preliminary documentation of the algal flora with regard to possible effects from future sewage outfalls. The algae were collected by hand and skin diving in the tidal zone of the following localities (Fig. 1). St. 1 Fort Jesus, coral rock with few live corals. St. 2 Reef flat outside Kenya Beach/Bamburi Beach. St. 3 Rock localities in the lagoon of Kenya Beach/Bamburi Beach. St. 4 Ras Junda, Port Tudor: Silted rock and rock pools. St. 5 Shelley Beach, reef flat towards the harbour entrance. St. 6 Nyali Bridge, muddy flat mingled with rock and gravel. In addition, an introductory survey was conducted of rocky shores in Port Kilindini (fig. 1). RESULTS AND COMMENTS Algae recorded from the above stations are listed in Table 1. Relatively poor algal communities were present in the port and creek area (represented by St. 4 and St. 6). In Port Kilindini observations of macroalgae were limited to few and small specimens of Ulva, Rhizoclonium and Enteromorpha. Inconspicuous amounts of blue-greens intermingled with diatoms were common on piers and the quite silted rocky shores. Several factors may contribute to the sparse algal growth in the creek environment: Dominance of muddy flats with scanty occurrence of rock substrate, generally sheltered habitats presumably favourable for mobile grazers, and also the exposure of the intertidal algae to the combined stress of high temperature and drying or silting and low light transmission. Whether the relatively low nutrient content has any significance is uncertain. If so, growth of benthic algae may be locally useful as indicators of fertilisation in the future. It would be premature, however, to regard the abundance of Ulva spp. and Enteromorpha at St. 6 as an example of this. Substrate conditions may be a more important factor. Page 2 J. Knutzen & E. Jaasund No. 168 Figure 1 . Sampling stations. It is possible that some pollution by oil slicks has put a restraint on algal growth in part of the creek area (Kilindini Harbour). Except for the sandy flats the lagoon environment (St. 3) is mostly sublittoral with some rock heads protruding above the sand-covered bottom. On the whole, angiosperms play a more dominant role than seaweeds. Even so, conspicuous algal covers were present, particularly in the lower littoral of the slope from the reef flat. These associations were largely comprised of Sargassum spp. and Halimeda spp. In addition to the tabulated species (St. 3), the following were found as drift weed on the beach: Boodlea composita (Harvey) Brand, Chaetomorpha crassa (C.Ag.) Kiitz., Sargassum subrepandum (Forsk.) J.Ag., Sphacelaria furcigera Kiitz., Gelidiopsis intricata (Ag.) Vickers and Colpomenia sinuosa (Roth) Derbes & Solier. The beach sand was somewhat contaminated by tar lumps of various size, but the lagoon com- munity of benthic algae did not seem to be affected. The reef flats (St. 2 and St. 5) and the rocky flat below Fort Jesus (St. I) showed rich algal growth; a large number of species taking advantage of the variable habitat of these localities. The complex community of the midlittoral is best characterized as a mosaic, with no clear zonation. The most striking algal element was the genus Viva, with at least three abundant species {U. fasciata Delile, U. pulchra Jaasund and U. reticulata Forsk.). U. rigida C. Ag. f. tropica was also commonly occurring. Often the species grew beside each other or the reticulate forms were entwined with the others. In spite of their somewhat patchy occurrence the Viva species alone, or together with other chlorophy- ceans, often gave the reef flats a green appearance. The other algae generally had a more uneven occurrence, perhaps with the exception of the ubiquitous, dark brown Cystoseira myrica (Gmelin) C.Ag. Among red algae, Laurencia papillosa (Forsk.) Greville, Gracilaria spp., and Yamadaella cenomyce (Decaisne) Abbott were the most pro- minent. Padina spp. and Halimeda spp. were commonly encountered, the former particularly in rock pools, Turbinaria and Hypnea spp. could also be common but not abundant. The prominence of the above algae is in accordance with observations further south in Kenya and in Tanzania. No. 168 Littoral Algae from Mombasa Page 3 No signs of pollutional effects were observed at the reef platform localities. Dictyosphaeria cavernosa (Forsk.) Borgesen were present but in modest amounts. This alga is observed to have caused damage to reefs by smothering of the corals after invasion presumably triggered off by eutrophic conditions (Johannes 1972). A special association of algae was abundant in the splash zone and down to somewhat below high water level, mainly at shady localities of over-hangs (St. 1) or sloping and silted cliffs (St. 4). This association consisted of Bostrychia tenella (Vahl) J. Ag., Catenella opuntia (Goodenough & Woodw.) Greville, Caloglossa leprieurii (Mont.) J. Ag. and Murayella periclados (J. Ag.) Schmitz. Table 1 Littoral algae collected in the Mombasa area 1974-75 Algae marked x are not in previously published records for Kenya. Stations Species 1 2 3 4 5 6 Rhodophyceae Acrocy sties nana Zanardini X Amansia glomerata C. Ag. X Amphiroa fragilissima (L.) Lamouroux X X Amphiroa rigida Lamouroux X X Bostrychia radicans Montagne X Bostrychia tenella (Vahl) J. Ag. X X Caloglossa leprieurii (Mont.) J. Ag. X Carpopeltis rigida (Harvey) Schmitz X Catenella opuntia (Goodenough & Woodw.) Grev. X Centroceras clavulatum (C.Ag.) Montagne X X Ceramium brevizonatum Petersen X X Ceramium masonii Dawson X X Ceramium taylorii Dawson X X Champia irregularis (Zanard.) Hauck X Champia parvula (C.Ag.) Harvey X Chondria armata Okamura X Chondrococcus harveyi J. Ag. X Chondrococcus hornemanni (Lyngb.) Schmitz X X Dasya elongata Sonder X X Endosiphonia clavigera (Wollny) Falkenberg X X Galaxaura obtusata (Ell. & Soil.) Lamouroux X Galaxaura tenera Kjellman X Galaxaura subverticillata Kjellman X Gelidiella acerosa (Forsk.) Feldmann & Hamel X X x Gelidiella tenuissima Feldmann & Hamel X X Gelidium cf. heteroplatos Borgesen Gracilaria corticata J. Ag. X X X Gracilaria fergusonii J. Ag. X Gracilaria salicornia (J. Ag.) Dawson X X X X Griffithsia tenuis C. Ag, X Haliptylon subulata (Ell. & Sol.) Johansen X Halymenia venusta Borgesen X Hypnea cornuta (Lamour.) J. Ag. X Hypnea esperi Bory X X Hypnea hamulosa (Turn.) Montagne X Hypnea musciformis (Wulf.) Lamouroux X X Hypnea pannosa J. Ag. X Jania adherens Lamouroux X X Laurencia intermedia Yamada X Laurencia papillosa (Forsk.) Greville X X Leveillea jungermannioides (Mart. & Her.) Harvey X X Liagora mauritiana Borgesen X X Lophosiphonia reptabunda (Suhr) Jaasund Lophosiphonia sp. X X Polysiphonia crassicollis Borgesen X X Spyridia hypnoides (Bory) Papenfuss X X Spyridia filamentosa (Wulf.) Harvey X Yamadaella cenomyce (Decaisne) Abbott X Page 4 Littoral Algae from Mombasa No. 168 Table 1 continued Species Phaeophyceae Cystoseira myrica (Gmelin) C. Ag. Cystoseira trinodis (Forsk.) C. Ag. Dictyota cf. pardalis Kiitzing Dictyota bartayresii Lamouroux sensu Vickers X Ectocarpus rhodocortonoides Borgesen Hydroclathms clathratus (Bory) Howe Padina bory ana Thivy (=P. conimersonii Bory) Padina gynmospora (Kiitz.) Vickers X Sargassum aqidfolium (Turn.) J. Ag. X Sargassum cf. binderi Sender Sargassum duplicatum J. Ag. Sargassum iUcifolium (Turn.) J. Ag. Sargassum spp. Spatoglossum asperum J. Ag. Sphacelaria sp. Stoechospermum marginatum (C. Ag.) Kiitzing Turbinaria conoides (J. Ag.) Kiitzing Turbinaria decurrens Bory Turbinaria kenyaensis Taylor Stations 1 2 3 4 5 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X Chlorophyceae Caulerpa fastigiata Montagne Caulerpa serrulata (Forsk.) J. Ag. em. Borgesen X X Chaetomorpha crassa (C. Ag) Kiitzing Chlorbdesmis fastigiata (C.Ag.) Ducker X X X Cladophoropsis sundanensis Reinbold X Codium dwarkense Borgesen X X X Codium geppii Schmidt X Dictyosphaeria cavernosa (Forsk.) Borgesen X Enteromorpha kylinii Bliding sensu Dawson X X X X Halimeda discoidea Decaisne Halimeda incrassata (Ell.) Lamouroux X X X Halimeda macroloba Decaisne X Halimeda opuntia (L.) Lamouroux X X Halimeda renschii Hauck X X Ulva fasciata Delile X X X X X Ulva pulchra Jaasund X Ulva reticulata Forskaal X X X X Ulva rigida C. Ag. f. tropica X X X REFERENCES Gerloflf, J. 1960. “Meeresalgen aus Kenya, I, Cyanophyta und Chlorophyta”. Willdenowia, 2, 4: 604-627. 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A. 1969. “A Note on the Possible Reproductive Structures in Kenyan Udotea orientalis A. and E. S. Gepp, (Chlorophyta)”. Jl. E. Afr. nat. Hist. Soc. natn. Mus. 27, No. 3 (118). 227-229. 1970. “Notes on Kenya Acetubalaria Lamouroux, (Chlorophyta)”. Jl. E. Afr. nat. Hist. Soc. natn Mus. 28, No. 1 (119): 47-52. Taylor, R. Wm. 1966. Notes on Indo-Pacific Turbinarias. Hydrobiologia 8: 91-100. {Received 31 October 1978) Published by The East Africa Natural History Society, Box 44486, Nairobi, Kenya and Printed by International Aeradio Limited, P.O. Box 19022, Nairobi. SMfTHSONIAN INSTITUTION LIBRARIES 3 9088 01313 7385