Gebreselassie, Selam Solomon
(2024)
Local and landscape scale patterns of macroinvertebrate diversity across ponds in Greater Kuala Lumpur, Malaysia.
PhD thesis, University of Nottingham Malaysia.
Abstract
Ponds and wetlands are increasingly recognized as valuable ecosystems in the urban landscape, mainly for their benefits to residents but increasingly for their capacity to support biodiversity. Their capacity to support diversity is critical for freshwater species and populations that continue to decline globally due to habitat loss and degradation. Conservation of these species is contingent on an understanding of the interactions between the built environment and the quality of urban wetland habitats. Research on urban biodiversity patterns from tropical regions that are experiencing rapid urbanization remains limited, and this is especially the case for ponds and wetlands. The aim of this thesis was therefore to characterize biodiversity patterns in ponds across Greater Kuala Lumpur (GKL), a rapidly expanding,tropical urban area, and understand the factors that influence these patterns. In so doing, the broader goals of the work were to highlight the biodiversity value of these abundant ecosystems and provide data to help direct management and conservation.
With aquatic macroinvertebrates as the focal group, biological, environmental and spatial data were collected for 28 ponds across GKL. Data were collected in both the wet and dry seasons (2021 - 2022). Data on pond chemistry and physical habitat characteristics (e.g. presence of macrophytes, size) were collected, while a range of broader, landscape-scale data were obtained from existing GIS and remote sensing sources. Landscape data included information on surrounding land cover and pond distributions across GKL. These data were used to characterize and examine variations in taxonomic and trait diversity and community composition, and understand the local and landscape-scale factors that influence ecological differences between ponds. Generalized Additive Modelling and Redundancy Analysis was performed to identify factors influencing the variation between ponds. To assess the importance of dispersal and connectivity between the ponds, functional connectivity metrics were derived using geospatial resistance surfaces based on land use and taxa dispersal distance information. In addition, landscape-scale pond network analysis was carried out to characterize structural connectivity for ponds across GKL.
Ponds in GKL exhibited considerable variation in taxonomic and functional alpha diversity, mainly explained by variations in pond characteristics, namely aquatic vegetation cover and suspended solids concentration. Surrounding land use, characterized by extent of built (impervious) land cover and road density explained variation in taxonomic and functional community composition (beta diversity). High taxonomic beta-diversity was recorded among pond invertebrate communities, primarily driven by species turnover (replacement). This was different to the patterns observed for trait-based beta-diversity which was primarily driven by richness difference. These findings are broadly consistent with findings from non-tropical regions, with similarities such as the positive relationship between aquatic vegetation cover and diversity measures and the high, turnover-driven beta-diversity. Some notable patterns found for the GKL ponds were the relative importance of ponds with smaller surface areas for diversity, the negative relationship between alpha diversity measures (taxonomic and functional) and suspendeded sediment concentration, and the association between communities with abundant gastropod taxa such as Physa and non-native Pomaceae and pond water conductivity.
Clustering analysis revealed two types of pond that exhibited statistically significant differences in taxonomic richness, diversity and community composition. The two types were primarily distinguished by differences in their size and distance from roads, further indicating the importance of both pond characteristics and surrounding land use. Increasing connectivity, quantified as the number of neighbouring ponds, was associated with increasing alpha diversity among sampled ponds but there were no significant associations between diversity and other structural or functional connectivity metrics such as Euclidean distance to nearest ponds. On the other hand, cost distance (representing functional connectivity) to neighbouring ponds explained some variation in community composition among the sample ponds. The landscape-scale pond network connectivity analysis showed that greater concentrations of highly connected pond clusters were present in two districts, with pond densities generally higher in more urban commercial/residential regions (Shah Alam, Putrajaya) than in the peri-urban or industrial (Hulu Langat, Klang) parts of GKL.
This study is one of the first to systematically examine local and landscape scale diversity patterns in tropical urban ponds. The work helps provide some points of guidance to support improved management of these habitats as well as to direct future research. These include (i) developing pond quality assessment criteria that integrate both local and landscape scale information, (ii) designing or redesigning ponds to have earth banks with greater aquatic vegetation cover, and (iii) coordinating pond management among various stakeholders in different administrative districts, to reflect the importance of connectivity across the whole city. Key to implementing these measures will be raising awareness of the ecological value of ponds in GKL that, as urban habitats, can be important in achieving the urban biodiversity conservation goals outlined in the Malaysian national policy on biodiversity. To support these goals, expanding the scope of research to other taxonomic groups using ponds and integrating ecosystem services as a critical component of pond research and management strategy are recommended. More research on the landscape-scale responses of tropical freshwater species to the urban environment will also be necessary to determine whether the patterns recorded in this study are consistent across other tropical cityscapes and to inform management strategies at regional scales.
| Item Type: |
Thesis (University of Nottingham only)
(PhD)
|
| Supervisors: |
Gibbins, Christopher
Hill, Matthew J.
Lechner, Alex
Teo, Fang Yenn |
| Keywords: |
urban biodiversity, ponds and wetlands, freshwater species, habitat loss, habitat degradation, conservation, built environment, urban wetland habitats, tropical regions, rapid urbanization |
| Subjects: |
T Technology > TD Environmental technology. Sanitary engineering |
| Faculties/Schools: |
University of Nottingham, Malaysia > Faculty of Science and Engineering — Science > School of Environmental and Geographical Sciences |
| Item ID: |
78426 |
| Depositing User: |
Gebreselassie, Selam
|
| Date Deposited: |
27 Jul 2024 04:40 |
| Last Modified: |
27 Jul 2024 04:40 |
| URI: |
https://eprints.nottingham.ac.uk/id/eprint/78426 |
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