Distribution, Interspecific Associations and Abundance of Aquatic Plants In
Total Page:16
File Type:pdf, Size:1020Kb
Peters J. 2000. Tetrazolium testing handbook. Las Cruces (NM): Association of Stoller EW, Wax LM. 1974. Dormancy changes and the fate of some annual Official Seed Analysts. Contribution 29. weed seeds in the soil. Weed Sci. 22:151-155. Peterson JE, Baldwin AH. 2004. Seedling emergence from seed banks of tidal Ter Heerdt GNJ, Verweij GL, Bekker RM, Bakker JP. 1996. An improved freshwater wetlands: response to inundation and sedimentation. Aquat method for seed bank analysis: seedling emergence after removing the Bot. 78:243-254. soil by sieving. Funct Ecol. 10:144-151. Poiani K, Johnson WC. 1988. Evaluation of the emergence method in esti- Thompson K. 1986. Small-scale heterogeneity in the seed bank of an acidic mating seed bank composition of prairie wetlands. Aquat Bot. 32:91-97. grassland. J Ecol. 74:733-738. Price JN, Wright BR, Gross CL, Whalley WR. 2010. Comparison of seedling Thompson K, Bakker JP, Bekker RM. 1997. The soil seed banks of North West emergence and seed extraction techniques for estimating the composi- Europe. Cambridge (UK): Cambridge University Press. 288 p. tion of soil seed banks. Methods Ecol Evol. 1:151-157. Thompson K, Grime JP. 1979. Seasonal variation in the seed banks of herba- Rahman MO. 2007. DNA fingerprinting in Utricularia L. section Utricularia as ceous species in ten contrasting habitats. J Ecol. 67:893-921. revealed by PCR based assay. Internat.J Bot. 3:56-63. Tsuyuzaki S. 1993. Seed viability after immersion in K2CO3 solution. Seed Sci Raynal DJ, Bazzaz FA. 1973. Establishment of early successional plant popu- Tech. 21:479-481. lations in forest and prairie soil. Ecology. 54:1335-1341. Tsuyuzaki S. 1994. Rapid seed extraction from soils by a flotation method. Roberts HA. 1981. Seed banks in soils. Adv Appl Biol. 6:1-55. Weed Res. 34:433-436. Roberts HA, Ricketts ME. 1979. Quantitative relationships between the weed van der Valk AG, Davis CB. 1976. The seed banks of prairie glacial marshes. flora after cultivation and the seed population in the soil. Weed Can J Bot. 54:1832-1838. Res.19:269-275. van der Valk AG, Davis CB. 1978. The role of seed banks in the vegetation Sampford MR. 1962. An introduction to sampling theory. Edinburgh (UK): dynamics of prairie glacial marshes. Ecology 59:322-335. Oliver and Boyd. 292 p. van der Valk AG, Davis CB. 1979. A reconstruction of the recent vegetational Skoglund J, Hytteborn H. 1990. Viable seeds in deposits of the former lakes history of a prairie marsh, Eagle Lake, Iowa, from its seed bank. Aquat Kvismaren and Hornborgasjon, Sweden. Aquat Bot. 37:271-290. Bot. 6:29-51. Smart RM, Barko JW 1985. Laboratory culture of submersed freshwater mac- van der Valk AG, Pederson RA, Davis CB. 1992. Restoration and creation of rophytes on natural sediments. Aquat Bot. 21:251-263. freshwater wetlands using seed banks. Wetl Ecol Manag. 1:1991-197. Smith RD, Dickie JB, Linington SH, Pritchard HW, Probert RJ. 2003. Seed van der Valk AG, Rosburg TR. 1997. Seed bank composition along a phos- conservation: turning science into practice. London (UK): The Royal phorus gradient in the northern Florida Everglades. Wetlands. 17:228- Botanic Gardens. 1023 p. 236. Smucker AJM, McBurney SL, Srivastava AK. 1982. Quantitative separation of Williges KA, Harris TT. 1995. Seed bank dynamics in the Lake Okeechobee roots from compacted soil profiles by hydropneumatic elutriation system. marsh ecosystem. Arch Hydrobiol, Special Issue: Ergebn Limnol (Adv Agron J. 74:500-503. Limnol). 45:79-94. Stoller EW, Wax LM. 1973. Periodicity of germination and emergence of Young JA, Evans RA, Raguse CA, Larson JR. 1981. Germinable seeds and peri- some annual weeds. Weed Sci. 21:574-580. odicity of germination in annual grasslands. Hilgardia. 49:1-3. J. Aquat. Plant Manage. 49:19-27 Distribution, interspecific associations and abundance of aquatic plants in Lake Bisina, Uganda BRIAN GIDUDU, R. S. COPELAND, F. WANDA, H. OCHAYA, J. P. CUDA, AND W. A. OVERHOLT* ABSTRACT pairwise associations between plant species revealed that the Chara sp. was negatively associated with Najas horrida A survey of floating-leafed and submersed aquatic ex Magn., Nymphaea caerulea Savigny, and Utricularia reflexa plants was conducted in Lake Bisina, Uganda. Seven of the Oliv., which was likely due to differences in habitat re- species collected were not previously reported from Lake quirements. A strong, positive association between N. caer- Bisina, including Stuckenia pectinata (L.) Börner, Utricular- ulea and U. reflexa may have been due to niche similarities, ia reflexa Oliv., Utricularia foliosa L., Caldesia parnassifolia but may also indicate a commensal relationship with U. re- (L.) Parl., Wiesneria filifolia Hook. f., Brasenia schreberi J. F. flexa performing well under shaded conditions provided Gmel., and a multicelluar algae, Chara sp. Examination of by N. caerula. Hydrilla verticillata was the only species asso- ciated with water clarity, with abundance increasing as tur- bidity increased. This study provides new baseline *First author: Crop Science Department, Makerere University, Kampala, Uganda; second author: International Centre of Insect Physiology and Ecol- information on the diversity, distribution, and interspecif- ogy, Nairobi, Kenya; third author: National Fisheries Resources Research ic associations of floating-leafed and submersed aquatic Institute, Jinja, Uganda; fourth author: University of Florida, Gainesville, FL, plants in Lake Bisina, Uganda, that will be useful for com- USA; fifth author: University of Florida, Fort Pierce, FL, USA. Correspond- parison with future biological studies. ing author’s E-mail: billover@ufl.edu. Received for publication July 28, 2010 and in revised form October 30, 2010. Key words: aquatic plants, hydrilla, macrophytes, shallow lake. J. Aquat. Plant Manage. 49: 2011. 19 INTRODUCTION pling were selected by traversing the lake along several transects and stopping at approximately 1 km intervals to Aquatic plants are central members of wetland communities collect samples. On three occasions (April 2008, January that provide food and shelter, directly or indirectly, for many or- 2009, and April 2009) an effort was made to sample as much ganisms; erosion control; oxygen enrichment of water through of the lake as possible by following 5 to 7 transects and revis- photosynthesis; nutrient cycling; absorption of pollutants (Cook iting many of the same sites. However, due to a lack of specif- 1974, Halls 1997); reduction of sediment suspension; refuges ic landmarks, drift of the boat during sampling, and for zooplankton from fish grazing; and suppression of algal inherent inaccuracy of the GPS units (30 m), it proved im- growth by competing for nutrients and light and the release of possible to sample the exact same sites repeatedly. On the allelopathic substances (Takamura et al. 2003). Aquatic plant other four occasions, sampling was targeted to cover isolated distribution, abundance, and vigor are influenced by abiotic bays and the extreme eastern and western portions of the factors including water temperature, pH, dissolved oxygen, nu- lake. In total, 199 locations were sampled with 11 to 46 loca- trient levels, turbidity (Squires et al. 2002), sediment type, water tions visited on each sampling occasion. At each sampling lo- and wind currents, depth, and changes in water levels (Wetzel cation, vegetation was collected from a boat by throwing a 1983). Biotic components of a given water body, such as the grappling hook attached to a rope and then dragging the presence and density of herbivorous fish (Hanson and Butler hook along the bottom until it was located below the boat. 1994), insects, mollusks, diseases (fungi, nematodes), plant-to- The hook was then slowly lifted to the surface and the col- plant interactions, and movement of vegetative portions of lected vegetation was placed on the bottom of the boat. At aquatic plants by man (e.g., plant parts entangled in fish nets) each location, the grappling hook was thrown three times, also influence the distribution and abundance of aquatic plants. each time in a different direction. Plant species were record- Lake Bisina (N 2.649, E 33.970) is part of the Kyoga lakes sys- ed when known, or a voucher sample was collected and tem in central Uganda. The Kyoga system receives inflow from pressed for later identification. Water depth was measured at Lake Victoria through the Nile River and from streams arising each location using a weighted rope, and water clarity was on the slopes of Mount Elgon to the east. The system includes measured on three of the sampling dates (June 2008, Janu- several lakes connected by large areas of papyrus swamp (Green ary 2009, and April 2009) with a Secchi disk. The relative 2009). Lake Bisina is east and upstream of the larger Lake Kyo- abundance of each plant species in each sample of three ga, through which the Nile flows. Bisina receives its fluvial input grappling-hook throws was estimated using a DAFOR scale from streams originating on Mount Elgon to the east and the (Hurford 2006) with scoring modified as follows: 5 (domi- Apendura River to the north. Slightly higher (1041 m a.s.l.) nant) ≥76% of the estimated biomass of a sample, 4 (abun- than Lake Kyoga (1026 m), it outflows gently through its west- dant) = 51-75%, 3 (frequent) = 26-50%, 2 (occasional) = 5- ern, swampy margins toward Kyoga. As such, Bisina is not direct- 25%, 1 (rare) = >0 and <5%, and 0 = absent. ly influenced by either the Nile or the downstream Kyoga- system lakes. Lake Bisina grows and shrinks depending on rain- fall, but in a typical year covers about 150 km2 with a mean Water samples depth of 3 m (Vanden Bossche and Bernacsek 1990). It is a des- ignated wetland of international importance (RAMSAR site) Water samples were taken from each sampled location on because of its unique biodiversity and support of rare and en- two occasions, January and April 2009, representing the dry dangered species (Byaruhanga and Kigoolo 2005).