The conservation value of artificial ponds in the Western Cape Province for aquatic beetles and bugs

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(1)THE CONSERVATION VALUE OF ARTIFICIAL PONDS IN THE WESTERN CAPE PROVINCE FOR AQUATIC BEETLES AND BUGS. By Emelie Arlette APINDA-LEGNOUO. Thesis presented in partial fulfillment of the requirements for the degree of Master of Science at the University of Stellenbosch. Supervisor: Prof. M. J. SAMWAYS. December 2007.

(2) DECLARATION. The work described in this thesis was carried out in the Cape Floristic Region, South Africa and in the Department of Conservation Ecology and Entomology and Centre for Agricultural Biodiversity, University of Stellenbosch, Stellenbosch. The study was conducted from September 2005 to September 2007, under the supervision of Professor Michael John SAMWAYS. I, the undersigned, hereby declared that the work contained in this thesis is my own original effort and that I have not previously, in its whole or in part, submitted it at any university for a degree. Where use has been made of the work of others it is properly acknowledged in the text.. Date:. Signature: E. A. Apinda-Legnouo. Copyright ©2007 Stellenbosch University All rights reserved. ii.

(3) ABSTRACT. Freshwater insect species and their host ecosystems are widely threatened, particularly within agricultural and urban landscapes of Mediterranean areas, including that of the Western Cape Province, South Africa. The study here determined the biodiversity value of nineteen artificial ponds (temporary and permanent) and two river margin sites in the Cape Floristic Region (CFR). The aim was to determine aquatic beetle and bug abundance and species richness in these ponds, a topic which has been hardly explored in South Africa. Sites were sampled from September 2005 to September 2006. A total of 18 677 aquatic beetle and bug individuals were sampled, representing 43 genera (28 beetle and 15 bug genera), 64 species (44 aquatic beetle and 20 bug species). Different pond types had distinct species assemblages. The associated physico-chemical characteristics of these sites were also investigated. The key environmental variable affecting aquatic beetle and bug distribution was naturalness (no human and environmental impact on waterbody). The results showed that the most important determinant of aquatic beetle and bug species richness across all sites was emergent macrophytes, such as Typha capensis and Persicaria decipiens. Artificial ponds in the CFR clearly increase the area of occupancy for insects, and therefore play a major role in conserving them. This is especially so when the ponds are at moderate temperatures (i.e.. 19º. C). Although all ponds contributed to the aquatic beetle and bug diversity in the region, they differed in relative value, depending on the combination of environmental variables affecting each pond.. iii.

(4) OPSOMMING. Varswater insekspesies en hulle ekosisteme word in die algemeen, veral in landbouen stedelike landskappe van mediterreense gebiede, insluitende dié van die WesKaap Provinsie, Suid-Afrika, bedreig. Hierdie studie het die biodiversiteitswaarde van negentien kunsmatige damme (tydelik en permanent) en twee rivierbanke in die Kaapse Floristiese Streek (KFS) bepaal. Die doel was om die volopheid en spesiesrykheid van waterkewers en wantse in hierdie damme te bepaal, ‘n onderwerp wat nog maar noueliks in Suid-Afrika ondersoek is. Die plekke is vanaf September 2005 tot September 2006 gemonster. ‘n Totaal van 18 677 waterkeweren wants individue is gemonster wat 43 genera (28 kewer- en 15 wantsgenera), 64 spesies (44 waterkeweren 20 wantsspesies). Verskillende dam tipes het verskillende. spesiesgroeperings. vertoon.. Die. geassosieerde. fisies-chemiese. eienskappe van die plekke is ook ondersoek. Die sleutel omgewingsveranderlike wat waterkeweren wantsverspreiding beïnvloed is natuurlikheid (geen mens- of omgewingsimpak op die watermassa). Die resultate het aangetoon dat die mees belangrike bepaler van waterkeweren wantsspesies rykheid by al die plekke deur opkomende makrofiete, soos Typha capensis en Persicaria decipiens, bepaal was. Kunsmatige damme in die KFS verhoog klaarblykelik die gebied van voorkoms van insekte en speel daarom ‘n hoofrol by die bewaring hiervan. Dit is veral die geval waar die damme matige temperature (~ 19º C) geniet. Alhoewel alle damme tot die diversiteit van waterkeweren wantsdiversiteit bygedra het, het hulle in relatiewe waardes verskil, afhangende van die kombinasie van omgewingsveranderlikes wat elke dam beïnvloed het.. iv.

(5) RESUMÉ Les espèces d’eau douce et leurs écosystèmes sont largement menacés, particulièrement dans des paysages agricoles et urbains des régions de la Méditerranée y compris ceux de la province du Cape Occidental, Afrique du Sud. L’étude ici a déterminé la valeur de la biodiversité de dix neuf étangs (temporaires et permanents) et deux sites, les rives d’une rivière dans la Région floristique du Cape (RFC). Le but était de déterminer l’abondance des scarabées et punaises aquatiques et leurs richesses dans ces étangs, un sujet qui n’a pas été largement exploré en Afrique du sud. Les scarabées et punaises aquatiques de 21 sites ont été échantionnées de Septembre 2005 à Septembre 2006. Un nombre total de 18 677 scarabées et punaises aquatiques individuelles étaient échantionnées, représentant 43 genres (28 scarabées et 15 punaises), 64 espèces (44 scarabées et 20 punaises). Les différents étangs avaient d’assemblages distincts d’espèces. Les caractéristiques physico-chémicales des sites ont été aussi déterminées. La variable environnementale clé affectant la distribution des scarabées et punaises aquatiques était le naturel (qui n'est pas le produit d'une pratique humaine). Les résultats de cette étude démontrent que le facteur limitant de la richesse des scarabées et punaises aquatiques à travers tous les sites était les plantes aquatiques, notamment Typha capensis et Persicaria decipiens. Des étangs dans le RFC clairement augmentent la surface d’occupation des insectes, et donc joue un rôle majeur dans leur conservation. Cette situation est essentiellement valable si et seulement si les étangs sont à une température moyenne (~ 19º C). Bien que tous les étangs aient contribué à la diversité des scarabées et punaises aquatiques dans la région, ils ont différé dans une valeur relative dépendant de la combinaison des variables environnementales affectant chaque étang.. v.

(6) DEDICATION. This thesis is dedicated to my late mum Agathe KEVANI, granny Ewombo Ondambouga and my uncle Ngabayi Opeleopele Joachim who sacrificed their needs for my interest. Mum I will always love you.. vi.

(7) ACKNOWLEDGEMENTS. I thank the Almighty God and Saviour, The Lord Jesus Christ, for placing me at the right place at the right time. I would also like to express my sincere gratitude to the following people and organizations: My two children, my daughter S. H. Ntiga and my son R. H. Atali-Ikoubou who gave me the strength to accomplish this work; My supervisor Prof. M.J. Samways for his guidance, advice and valuable contributions made towards this study. Dr Clive Turner and Mr. P. Reavell for guiding me in the identification of aquatic beetles and bugs; Dr A. Timm and A.P. Mayekiso of South African Museum for providing material and photographing insects; Mr. G. Saphou-Bivigat, Mr. E. M. Ella, A. Johnson, H. S. Ndinga-Koumba-Binza and L. S. Soami for their invaluable assistance and enthusiasm in the field and for driving me to the study sites; Guys without you, this thesis would not have been done. Prof. H. Geertsema for continual advice and help and for providing me the laboratory equipment. L. Welgemoed from the Geography Department, Stellenbosch University for producing site map. N. Mgocheki, E. Bredenhand, R. N. N. Magoba, C. S. Schoeman, H. R. Memiaghe R. Gaigher and J. P. Samaika who shared their ecological and statistical knowledge with me. Mr. A. Johnson, C. Louw and M. Isaacks for technical assistance. A big thank you goes to my good friends who assisted me. I’m grateful to them for many hours in the field. I should mention here Yoba Ngoma Habib Patrick Richard and Bivigou Koumba Achille Mayelle. South African Museum for letting me use their specimens. Dr Dee Snijman of Compton Herbarium and P. E. Reavell for aquatic plant identification; The Conservation Ecology and Entomology Department for its contribution in this study;. vii.

(8) The Staff and fellow students of the Department of Conservation Ecology and Entomology for support and advice; The Gabonese government, Mr. F. Ntsissi and my supervisor Michael John Samways for financial support; Managers and farm owners of the following: Vergelegen Wine Estate, Meerlust farm, Middelvlei farm, Libertas farm, Fleurbaix farm, Heidelberg and Stellenbosch municipalities, Infruitech, Protea Hotel and Jonkershoek nature reserve for permission to sample on their property; thank you very much. Special thanks to my family for their love, support and encouragement through this study, especially, C. Nkiessouma, C. Onganana, L. Lembeme, J. Mvaboua, F. Apinda, J. P. Avouya, O. Apinda, P. Opirina, SR. Andagaombagui, N. Efatouni, R. F Onganana, M. Ngokho, G. M. Onganaga, G. Apinda Antsaraga, G. Avouma, S. Ngoungoulou, G. S. R. Ossouo, L. R. Ngoma, A. R. Samy, E. Nkounandjiami and H. F. R Ndzoho Bininame, Lydie and Rita.. viii.

(9) FIGURES AND TABLES. List of Figures. Figure 2.1: Location map of 21 sampling sites in the Western Cape. Sites 2 and 4 are lotic sites, the remaining are artificial ponds (lentic sites)………………………………………………………..………. .8 Figure 2.2.1: The J. S. Marais park reservoir (STAS 1)…………………………………………………..11 Figure 2.2.2: The upper river zone, Eerste river margin site (STAS 2)………………………………….11 Figure 2.2.3: The Kleinplaas dam in Jonkershoek reserve (STAS3)……………………………………11 Figure 2.2.4: The mountain-stream zone, Eerste river margin site (STAS 4)………………………….12 Figure 2.2.5: The first Protea Hotel reservoir (STAS 5)…………………………………………………..12 Figure 2.2.6: The second Protea Hotel reservoir (STAS 6) ……………………………………………..12 Figure 2.2.7: The first Vergelegen reservoir (STAS 7)……………………………………………………13 Figure 2.2.8: The second Vergelegen reservoir (STAS 8)………………………………………….……13 Figure 2.2.9: The Somerset Mall reservoir (STAS 9), a neglected reservoir…………………………. .13 Figure 2.2.10: The Middelvlei reservoir (STAS 10)………………………………………………………..14 Figure 2.2.11: The third Vergelegen reservoir (STAS 11), an attenuation pond ………………………14 Figure 2.2.12: The fourth Vergelegen reservoir (STAS 12), an attenuation pond…………………......14 Figure 2.2.13: The first Nietvoorbij reservoir (STAS 13)…………………………………………………..15 Figure 2.2.14: The second Nietvoorbij reservoir (STAS 14)……………………………………….……..15 Figure 2.2.15: The reservoir near Meerlust farm (STAS 15), a neglected reservoir …………………..15 Figure 2.2.16: The first Meerlust reservoir (STAS 16)………………………………………...…………..16 Figure 2.2.17: The second Meerlust reservoir (STAS 17)………………………………………………...16 Figure 2.2.18: The Fleurbaix reservoir (STAS 18)…………………………………………………………16 Figure 2.2.19: The Libertas reservoir (STAS 19)………………………………………...…………….…..17 Figure 2.2.20: The Golf course reservoir (STAS 20)………………………………………………...…….17 Figure 2.2.21: The Somerset West reservoir (STAS 21)………………………………………..…………17 Figure 2.3: Schematic diagram of a single pond site showing the six replicate quadrats. They were not necessarily equally spaced but rather chosen to represent the full range of habitat types around the pond…………………………………………………………………………………………………………….19. ix.

(10) Figure 2.4 : Schematic diagram of a plant quadrat showing the arrangement of pins along the wooden sampling bar used to record plant ‘hits’…………………………………………………………………….22 Figure 3.1: Total number of aquatic beetle and bug individuals recorded over the entire sampling period at each site, and arranged in order of rank abundance. For site number, see Table 3.1…….28 Figure 3.2.1: Total number of aquatic beetle individuals recorded over the whole sampling period at each of the sites, and arranged in order of rank abundance. For site numbers, see Table 3.1…..…29 Figure 3.2.2: Total number of individual aquatic bug individuals recorded over the whole sampling period at each of the sites, and arranged in order of rank abundance. For site numbers, see Table 3.1……………………………………………………………………………………………….…..…29 Figure 3.3.1: Seasonal effect on aquatic beetle and bug individuals sampled per site. For site numbers, see Table 3.1…………………………………………………………………………………..…30 Figure 3.3.2: Seasonal effect on aquatic beetle and bug individuals sampled per site. For site numbers, see Table 3.1…………………………………………………………………………………..…30 Figure 3.3.3: Seasonal effect on aquatic beetle and bug individuals sampled per site. For site numbers, see Table 3.1…………………………………………………………………………………..…30 Figure 3.3.4: Seasonal effect on aquatic beetle and bug individuals sampled per site. For site numbers, see Table 3.1…………………………………………………………………………………..…30 Figure 3.4: Total number of adult aquatic beetle and bug individuals sampled during the first sampling period from 15 September 2005 to 20 September 2005. For site numbers, see Table 3.1………....31 Figure 3.5: Total number of adult aquatic beetle and bug individuals sampled during the second sampling period from 15 November 2005 to 20 November 2005. For site numbers, see Table 3.1…………………………………………………………………………………………………..….31 Figure 3.6: Total number of adult aquatic beetle and bug individuals sampled during the third sampling period from 15 December 2005 to 20 December 2005. For site numbers, see Table 3.1……………32 Figure 3.7: Total number of adult beetle and bug individuals sampled during the fourth sampling period from 15 February 2006 to 20 February 2006. For site numbers, see Table 3.1……………………….32 Figure 3.8: Total number of adult aquatic beetle and bug individuals sampled during the fifth sampling period from 15 April 2006 to 20 April 2006. For site numbers, see Table 3.1………………………….33 Figure 3.9: Total number adult aquatic beetle and bug individuals sampled during the sixth sampling period from 15 May 2006 to 20 May 2006. For site numbers, see Table 3.1…………………………..33 Figure 3.10: Total number of adult aquatic beetle and bug individuals sampled during the seventh sampling period from 10 June 2006 to 15 June 2006. For site numbers, see Table 3.1……………..34 Figure 3.11: Total number of aquatic beetle and bug individuals sampled during the eighth sampling period from 20 August 2006 to 25 August 2006. For site numbers, see Table 3.1…………………...34 Figure 3.12.1: Aquatic beetle and bug species richness at each site, arranged in order of rank abundance. For site numbers, see Table 3.1……………………………………………………………..36 Figure 3.12.2: Aquatic beetle species richness at each site, arranged in order of rank abundance. For site numbers, see Table 3.1………………………………………………………………………………...37 Figure 3.12.3: Aquatic bug species richness at each site, arranged in order of rank abundance. For site numbers, see Table 3.1………………………………………………………………………………...37 Figure 3.13: Log abundance curve of aquatic beetle and bug individuals recorded at the J. S. Marais pond (1) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2………………………………………………………………………………….....39 x.

(11) Figure 3.14: Log abundance curve of aquatic beetle and bug individuals recorded at the upper Eerste river margin site (2) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table3.2……….……………………………………………..……..………..…39 Figure 3.15: Log abundance curve of aquatic beetle and bug individuals recorded at the Kleinplaas dam (Jonkershoek)(3) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2……………………………………………………………………40 Figure 3.16: Log abundance curve of aquatic beetle and bug individuals recorded at the mountain Eerste river margin site (4) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2……………………………………………………………….40 Figure 3.17: Log abundance curve of aquatic beetle and bug individuals recorded at the first Protea Hotel reservoir (5) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2………………………………………………………………………..41 Figure 3.18: Log abundance curve of aquatic beetle and bug individuals recorded at the second Protea Hotel reservoir (6) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2………………………………………………………………41 Figure 3.19: Log abundance curve of aquatic beetle and bug individuals recorded at the Vergelegen first dam (7) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2…………………………………………………………………………...42 Figure 3.20: Log abundance curve of aquatic beetle and bug individuals recorded at the Vergelegen second dam (8) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2………………………………………………………………………...…42 Figure 3.21: Log abundance curve of aquatic beetle and bug individuals recorded at the Somerset Mall reservoir (9) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2…………………………………………………………………………...43 Figure 3.22: Log abundance curve of aquatic beetle and bug individuals recorded at the Middelvlei reservoir (10) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2……………………………………………………………………………43 Figure 3.23: Log abundance curve of aquatic beetle and bug individuals recorded at the Vergelegen third dam (11) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2……………………………………………………………………………44 Figure 3.24: Log abundance curve of aquatic beetle and bug individuals recorded at the Vergelegen fourth dam (12) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2……………………………………………………………………………44 Figure 3.25: Log abundance curve of aquatic beetle and bug individuals recorded at the first Nietvoorbij first reservoir (13) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2………………………………………………………….45 Figure 3.26: Log abundance curve of aquatic beetle and bug individuals recorded at the second Nietvoorbij reservoir (14) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2……………………………………………………………….45 Figure 3.27: Log abundance curve of aquatic beetle and bug individuals recorded at the reservoir near Meerlust farm (15) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2.………………………………………………………………….…….46 Figure 3.28: Log abundance curve of aquatic beetle and bug individuals recorded at the Meerlust first reservoir (16) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2…………………………………………………………………………...47 Figure 3.29: Log abundance curve of aquatic beetle and bug individuals recorded at the Meerlust second reservoir (17) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2…………………………………………………………………..47 xi.

(12) Figure 3.30: Log abundance curve of aquatic beetle and bug individuals recorded at the Fleurbaix reservoir (18) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2……………………………………………………………………………48 Figure 3.31: Log abundance curve of aquatic beetle and bug individuals recorded at the Libertas reservoir (19) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2…………………………………………………………………………...48 Figure 3.32: Log abundance curve of aquatic beetle and bug individuals recorded at the Golf course area reservoir (20) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2………………………………………………………………………...49 Figure 3.33: Log abundance curve of aquatic beetle and bug individuals recorded at the Somerset West pond (21) over the entire sampling period, arranged in order of rank abundance. For the key to species codes, refer to Table 3.2…………………………………………………………………………...49 Figure 3.34: Dendogram of the 21 sites based on aquatic beetles and bugs abundance during the whole sampling period. For full site numbers and names, see Table 3.1……………………………...59 Figure 3.35: Dendogram of the 21 sites, based on all environmental variables, naturalness, size of site, permanence, lentic/lotic spectrum, riparian vegetation, pH, conductivity, dissolved oxygen, elevation and temperature . For site numbers and names, see Table 3.1………………………….….59 Figure 3.36: Canonical Correspondence Analysis (CCA) ordination diagram of adult aquatic beetle and bug species and environmental variables from the 21 sites. Variables are represented by arrows; species are represented by triangle, and sites by circles (black circles represent lotic sites). A triplot was done on axes 1 and 2. For full species and environmental variable abbreviations see Appendix 3.3, and for full site numbers refer to Table 3.1……………………………………………………….…..62 Figure 3.37: Canonical Correspondence Analysis (CCA) ordination diagram of adult beetle and bug species. Species are represented by triangles. For species abbreviations see Appendix 3.3……………………………………………………………………………………………………………....64 Figure 3.38: Canonical Correspondence Analysis (CCA) ordination diagram of environmental variables. Each variable is represented by length of arrow……………………………………………....65 Figure 3.39: Canonical Correspondence Analysis (CCA) ordination diagram of adult aquatic beetle and bug species and environmental variables. Variables are represented by arrows, and species are represented by triangles. For environmental variables and species abbreviations, see Appendix 3.3. ………………………………………………………………………………………………………………..…66 Figure 3.40: Mean temperature (ºC) and standard deviation of each of the sites over the whole sampling. period.. For. site. numbers. see. Table. 3.1…………………………………………………………………………………………………….……..….74. xii.

(13) Figure 3.41: Mean conductivity (ms.cm-1) standard deviation of each of the sites over the whole sampling. period.. For. site. numbers. see. Table. 3.1……………………………………………………………………………………………………….……...76 Figure 3.42: Mean percentage dissolved oxygen (%) standard deviation of each of the sites over the whole. sampling. period.. For. site. numbers. see. Table. 3.1……………………………………………………………………………………………………………….78 Figure 3.43: Mean pH and standard deviation for each of the sites over the whole sampling period. For site. numbers. see. Table. 3.1………………………………………………………………………………………………………………82 Figure 3.44: Venn diagram showing the overlap of aquatic beetle and bug species between lotic, permanent lentic and temporary lentic sites. Number of species unique to each group of sites, number of species shared between group of sites and number of species shared between all three groups of sites. The Jaccard Index (Cj) of similarity is shown between each pair of groups…………………… …………………………………………………………………………………………………………………..89. xiii.

(14) List of Tables. Table 2.1: Descriptions of the ponds investigated in this survey (N/A=not applicable, WP=water permanency, ELEV=elevation)……………………………………………………………………………….9 Table 2.2: Environmemtal variables measured at each site……………………………………………...10 Table 3.1: Quick reference table to sites……………………………………………………………………25 Table 3.2: List of recorded beetle and bug species, with their code name and their distribution. …………………………………………………………………………………………………………………...52 Table 3.3: Summary of Eigenvalues and Monte Carlo test for the CCA ordination diagram………….68 Table3.4: Conditional effect from direct gradient analysis methods CCA (Weighted averaging model) showing environmental variables, in descending order of importance in affecting species abundance …………………………………………………………………………………………………………………...68 Table 3.5: Macrophytes recorded in four selected ponds…………….…………………………………...85 Table 3.6: Distribution of aquatic beetle and bug species the 21 sites with their code name and their IUCN Red list status (where appropriate)…………………………………………………………………...90 Table 3.7: Aquatic beetle and bug phenology……………………………………………………………....95. xiv.

(15) Appendices Appendix 1.1:. Number of aquatic beetle and bug individuals collected over the whole sampling. period…………………………………………………………………………………………………...………117. Appendix 1.2: Number of aquatic beetles and bugs sampled across each of the 21 sites over the whole sampling period………………………………………………………………………………………..128. Appendix 2: Numbers of aquatic beetle and bug individuals sampled across each of the 21 sites but broken down by season………………………………………………………………………………………129. Appendix 3.1.1: List of recorded aquatic beetles and bugs during the first sampling (from 15 September 2005 to 20 September 2005)…………………………………………………………………..130 Appendix 3.1.2: List of recorded aquatic beetles and bugs during the second sampling (from 15 November 2005 to 20 November 2005)…………………………………………………………………....134 Appendix 3.1.3: List of recorded aquatic beetles and bugs during the third sampling (from 15 December 2005 to 20 December 2005)…………………………………………………………..………..138 Appendix 3.1.4: List of recorded aquatic beetles and bugs during the fourth sampling (from 15 February 2006 to 20 February 2006)…………………………………………………………………….…142 Appendix 3.1.5: List of recorded aquatic beetles and bugs during the fifth sampling (from 15 April 2006 to 20 April 2006)………………………………………………………………………………………………146 Appendix 3.1.6: List of recorded aquatic beetles and bugs during the sixth sampling (from 15 May 2006 to 20 May 2006)………………………………………………………………………………………..150 Appendix 3.1.7: List of recorded aquatic beetles and bugs during the seventh sampling (from 15 July 2006 to 20 July 2006)…………………………………………………………………………………………154 Appendix 3.1.8: List of recorded aquatic beetles and bugs during the eighth sampling (from 15 August 2006 to 20 August 2006)……………………………………………………………………………………..158. xv.

(16) Appendix 3.2: Numbers of aquatic beetle and bug assemblages recorded as all 21 sites broken down according to sampling period…………………………………………………………………………..........162 Appendix 3.3: Site species, environmental variables, abbreviations and number used in analysis……. …………………………………………………………………………………………………………………..163 Appendix 4: Numbers of beetle and bug species sampling across the 21 sites…………………….…165 Appendix 5: Location of some rare species across the selected sites……………………………….…166 Appendix 6: Species similarity matrix, for site abbreviation refers to quick reference table to sites… …………………………………………………………………………………………………….……………167 Appendix 7: Environmental variable similarity matrix, for site abbreviation refer to quick reference table to sites………………………………………………………………………………………………………….168 Appendix 8.1: Spearman's Rank Correlation Coefficients relating environmental variables to aquatic beetles and bugs (red correlation coefficients are significant at p<0.05)……………………………….169 Appendix 8.2: Spearman's Rank Correlation Coefficients relating environmental variables to aquatic beetles (red correlation coefficients are significant at p<0.05)…………………………………………..170 Appendix 9: Summary of Stepwise regression showing correlations between aquatic beetle and bug species and physico-chemical factors…………………………………………………………………..…172 Appendix 10.1: Statistics for Table of Number of species by Conductivity…………………………….172 Appendix 10.2: Statistics for Table of Number of species by Dissolved oxygen……………………...172 Appendix 11.1: Measured temperature (º C) at each microhabitat during aquatic beetle and bug sampling period……………………………………………………………………………………………....173 Appendix 11.2: Measured conductivity (ms/cm) at each microhabitat during aquatic beetle and bug sampling period……………………………………………………………………………………………...................175 Appendix 11.3: Measured dissolved oxygen (%) at each microhabitat during aquatic beetle and bug sampling period……………………………………………………………………………………………...................177 Appendix 11.4: Measured pH at each microhabitat during aquatic beetle and bug sampling period……………………………………………………………………………………………...................179 Appendix12.1: Laccocoris cf salina………………………………………………………………………...181 Appendix12.2: Appasus capensis…………………………………………………………………............181 Appendix 12.3: Enithares sobria…………………………………………………………………………………………………………..182 Appendix12.4: Rhagovelia nigricans……………………………………………………………………………………………………….182 Appendix12.5: Micronecta piccanin……………………………………………………………………...…182. xvi.

(17) Appendix 12.6: Anisops sardea………………………………………………………………………………………………………….183 Appendix 12.7: Laccocoris limigenus……………………………………………………………………………………………………....183 Appendix 12.8: Gerris swakopensis………………………………………………………………………..183 Appendix12.9: Sigara meridionalis………………………………………………………………………….184 Appendix12.10: Micronecta scutellaris……………………………………………………………………..184 Appendix12.11: Primospes suturalis…………………………………………………………………….….185 Appendix12.12: Gyrinus vicinus……………………………………………………………………............185 Appendix12.13: Berosus sp……………………………………………………………………………….…185 Appendix12.14: Canthyporus navigator………………………………………………………………….…186 Appendix12.15: Hyphydrus soni………………………………………………………………………….....186 Appendix12.16: Enochrus sp………………………………………………………………………………...186 Appendix12.17: Ochthebius pedalis………………………………………………………….……………..187 Appendix12.18: Laccophilus cyclopis…………………………………………………………………….…187 Appendix12.19:Bidessus mundulus………………………………………………………………………...187 Appendix12.20: Dineutus punctatus………………………………………………………………………...188 Appendix12.21: Herophydrus inquinatus………………………………………………………………..….188 Appendix12.22: Paracymus amplus…………………………………………………………………..…….188 Appendix12.23: Enochrus larva………………………………………………………………………..…....189 Appendix12.24: Guignotus lineolatus…………………………………………………………………….....189 Appendix12.25:Hydropeplus larva……………………………………………………………….………….189 Appendix12.26:Dytiscidae larva……………………………………………………………………………..190. xvii.

(18) TABLE OF CONTENTS. DECLARATION……………………………………………………………………………………................ii ABSTRACT………………………………………………………………………….................................…iii OPSOMMING………………………………………………..…………………………………………….…..iv RESUME……………………………………………………………………………………………………..…v DEDICATION ……………………………………………………………………………………………....…vi ACKNOWLEDGEMENTS……………………………………………………………………………...….....vii FIGURES AND TABLES………………………………………………………………………………..…....ix List of Figures……………………………………………………………………………………………….....ix List of Tables…………………………………………………………………………………………………..xiv Appendices…………………………………………………………………………………………………….xv TABLE OF CONTENTS………………………………………………………………..... …………………xviii. CHAPTER 1.........................................................................................................................................1 INTRODUCTION..................................................................................................................................1 1.1 Threats to freshwater systems…………………………………………………………………………...1 1.2 Pond conservation………………………………………………………………………………………...2 1.3 Aims and objectives……………………………………………………………………………………....5 CHAPTER 2…………………………………………………………………………………………………....6 SITES, MATERIAL AND METHODS………………………………………………………………............6 2.1 Study area………………………………………………………………………………………………….6 2.1.1 Site selection…………………………………………………………………………………………….6 2.1.2 Sampling spots (sampling units)………………………………………………………………..…….18 2.2 Sampling unit variables……………………………………………………………………………..…...19 xviii.

(19) 2.3 Field data collection…………………………………………………………………………………..…..20 2.3.1 Aquatic beetles and bugs………………………………………………………………….. …………20 2.3.2 Aquatic plants...………………………………………………………………………………………...21 2.4 Data analysis……………………………………………………………………………………………...22 CHAPTER 3……………………………………………………………………………………………….…..25 RESULTS………………………………………………………………………………………………………25 3.1 Aquatic beetle and bug presence…………………………………………………………………….....25 3.1.1 Species abundance…………………………………………………………………………………….25 3.1.2 Seasonal effect on aquatic beetle and bug abundance……………………………………………………………………………………………………...26 3.2 Species richness…………………………………………………………………………………….…….35 3.2.1 Species abundance curves……………………………………………………………………………38 3.3 Species conservation status……………………………………………………………………………..50 3.4 Similarity between different sites………………………………………………………………………..58 3.5 Impact of environmental variables on aquatic beetle and bug species……………………………..60 3.5.1 Size……………………………………………………………………………………………………….70 3.5.2 Permanence……………………………………………………………………………………………..70 3.5.3 Lentic/Lotic spectrum………………………..………………………………………………………….71 3.5.4 Elevation…………………………………………………………………………………………………72 3.5.5 Temperature…………………………………………………...………………………………….…….72 3.5.6 Conductivity………………………………………………………….…………………………….…....75 3.5.7 Dissolved oxygen……………………………………………………………………………………….77 3.5.8 pH………………………………………………………………………………………………………...79 3.5.9 Riparian vegetation……………………………………………………………………………….…….80 3.5.10 Naturalness………………………………………………………………………………………….…81 3.6 Fine comparison of microhabitats in ponds…………………………………………………………… 83 3.7 Species distribution……………………………………………………………………………………… 86 3.7.1 Aquatic beetles………………………………………………………………………………………… 87 3.7.2 Aquatic bugs…………………………………………………………………………………………… 87 3.8 Species phenology………………………………………………………………………………………. 94. xix.

(20) CHAPTER 4…………………………………………………………………………………………………... 96 DISCUSSION AND CONCLUSIONS………………………………………………………………………. 96 4.1 Importance of ponds for aquatic beetles and bugs…………………………………………………... 96 4.2 Conservation management implications……………………………………………………………….101 4.3 Recommendations for future research……...………………………………………………………….102 4.4 Conclusions………………………………………………………………………………………………..103 REFERENCES………………………………………………………………………………………………...105 APPENDICES…………………………………………………………………………................................116. xx.

(21) CHAPTER 1 INTRODUCTION. 1.1 Threats to freshwater systems Freshwater ecosystems are aquatic systems which contain drinkable water or water with low salt content. Freshwater bodies include lakes, ponds, rivers, streams, reservoirs, wetlands, and groundwater. They provide the majority of drinking water resources, water resources for agriculture, industry, sanitation, as well as food, including fish and shellfish1. Freshwater makes up only about 0.01% of the world’s water (and about 0.8% of the Earth’s surface), while about 100 000 species out of 1.3 million so far scientifically described species (=8%). This means that freshwater is much richer in species than the world average. Of the world’s ecosystems, freshwaters are under most pressure and inevitably the threats to freshwater biodiversity are particularly severe (Dudgeon et al., 2006). Evidence is accumulating that over 20% of freshwater species are currently threatened or extinct, with indications from North America that extinction rates are four to five times higher than in terrestrial systems (Ricciardi and Rusmussen, 1999).. 1. www.epa.gov/bioindicators/aquatic/freshwater.html - 23k (21-02-2006). EA Apinda-Legnouo / MSc Thesis. The Conservation Value of Artificial Ponds in the Western Cape Province for Aquatic Beetles and Bugs. 1.

(22) 1.2 Pond conservation The Cape Floristic Region (South Africa) is a global biodiversity hotspot for plants (Goldblatt & Manning, 2000). However, little is known of invertebrates 2, especially those associated with standing water, including ponds, which are defined here as ‘water bodies between 1m2 and 2 ha in area, which hold water for four months of the year or more’ (Pond Conservation Group, 1993). They are an important resource for wildlife, and are home to a wide variety of plants, invertebrates, amphibians, birds and mammals (Bronmark and Hansson, 1998). However, they are vulnerable to changes in land use and other human activities. These ecosystems are threatened from the impacts of sewage, effluent from industries, pesticides, irrigated water, urban development, and invasion by various alien organisms (Samways, 2005). Ponds can be natural, or created artificially (reservoirs) for human use during water-stressed periods. The activities practiced around ponds can impoverish their biota and disturb their ecological processes, leading to the loss of their natural value. Today, ponds are beginning to receive attention for conservation as they can support important assemblages of rare and threatened freshwater species (Collinson et al., 1995 and Williams et al., 2003), and they can contribute to risks of reducing extinction by increasing the area of occupancy (Samways, 2005).. 2. http://finebushpeople.co.za/fynbos_index.htm (26-02-2006). EA Apinda-Legnouo / MSc Thesis. The Conservation Value of Artificial Ponds in the Western Cape Province for Aquatic Beetles and Bugs. 2.

(23) Ponds have only recently been recognized as important habitats for the maintenance of biodiversity (Oertli et al., 2005). Scientific interest in these freshwater bodies has increased over the past decade, with an increasing focus on species diversity and its conservation. Interest in pond insects and concern for their conservation continues to grow. Insects in some industrialized countries have been the subjects of submissions made to certain commissions. Several studies on ponds and their diversity have been made by many authors. In North America, for example, Hoffmann et al. (2004) focused on mountain ponds and lakes for dragonflies (Odonata), macroinvertebrates, fish, amphibians, plankton and macrophytes. In Europe, Jeffries (1991) provided information on the species richness of some ponds in Scotland and England, while Collinson et al. (1995) considered the importance of conserving both temporary and permanent ponds for aquatic insects. Foster (1991) gave some strategies for conserving aquatic beetles and wetland habitats. Briers and Biggs (2003) worked on ponds for macroinvertebrates, Cottenie and Meester (2003) focused on shallow ponds and Cladocera, while Foggo et al. (2003) investigated ponds for macroinvertebrates, Williams et al. (2003) investigated rivers, streams, ditches, ponds for macroinvertebrates and macrophytes, Angelibert et al. (2004) focused on macroinvertebrates, zooplankton and macrophytes, Boix and Quintana (2004) surveyed ponds and Microcrustacea and Insecta, Bazzanti et al. (2000) described temporary and permanent pond for macroinvertebrates, Grillas et al. (2004). described. temporary. ponds. as. habitats. for. macrocrustacea,. macroinvertebrates, amphibians and macrophytes, Karaus (2004) worked on Parafluvial ponds and Ephemeroptera, Plecoptera and Trichoptera (EPT) taxa, and Nicolet et al. (2004) investigated temporary ponds for macroinvertebrates and macrophytes and Gee et al. (1997) focused on macrophytes and macroinvertebrates of ponds. Benthic macroinvertebrates, as they are widespread and sensitive to environmental changes are the organisms often used to assess freshwater quality (Resh, 1995). In addition, Sanchez-Fernandez EA Apinda-Legnouo / MSc Thesis. The Conservation Value of Artificial Ponds in the Western Cape Province for Aquatic Beetles and Bugs. 3.

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