Biological diversity of freshwater fishes in small streams in peninsular Malaysia
Abstract
Peninsular Malaysia has a diverse flora and fauna, much of which is yet to be documented.
The freshwater fishes are one important group that have received little attention. Accordingly,
the overarching goal of my study is to investigate the pattern of species richness and analyse
the community composition and assemblage structure of fishes in the small streams in
Peninsular Malaysia. Small stream habitats appeared to be particularly important repositories
of fish biodiversity in this region thus obtaining a reliable census of species occurring in such
habitats is critical for conservation and management of biodiversity. Although samplings
were far from completed, these habitats support a great variety of species with more than 100
species were recorded from fifty streams sampled in this study. A few are extremely rare with
restricted distribution and can thus be considered important in biodiversity conservation of
the Peninsular Malaysian ichthyofauna. Human-influenced modification of lowland,
headwater stream habitats in Peninsular Malaysia is common and often exemplified by the
creation of pools in stretches of rapids and riffles. However, it was not possible to separate
pristine and disturbed sites which contained almost identical for species diversity. These
findings suggest that local habitat modification does not necessarily cause a decrease in
freshwater fish diversity, with only minor negative consequences for other community
variables recorded in this study, and therefore raise interesting issues regarding conservation.
That said it remains premature to conclude that small stream fishes are insensitive to
disturbance and thus their potential utility as bioindicators of disturbance-influenced
community changes remain to be confirmed. The maintenance practises being applied to
small streams modified for recreational usage were not imposing detectable negative
consequences, at least across the sites sampled in this study. The rich diversity of tropical
stream environments is the result of both within-habitat (alpha) diversity and between-habitat
(beta) diversity. The results showed that there was substantial beta diversity particularly
amongst sites that are geographically separated from one another. On the contrary, the lowest
beta diversity values were portrayed by contiguous sites. Many fishes exhibited discontinuous
patterns of distribution and were considered to be rare while only a handful were widely
distributed and abundant. Ordination based on the relative resemblance of fish communities
to one another support the existence of two distinct ichthyogeographic divisions in Peninsular
Malaysia. It was possible to assign the species recorded to all seven of Rabinowitz’s
categories of rarity, with at least 10 restricted to a single stream and locally scarce, although
not all of these could be described as hyper-endemic. It is recommended that a sizeable
augmentation of the existing protected areas is needed to safeguard Malaysia’s exceptionally
diverse stream-dwelling fauna of which fishes are simply the most well-known inhabitants.
Conservation managers should therefore place particular emphasis on small streams since
localities in close proximity to one another can exhibit surprisingly high beta diversity,
meaning that partial or small-scale habitat protection may prove insufficient.
Type
Thesis, PhD Doctor of Philosophy
Rights
Embargo Reason: Embargo period has ended, thesis made available in accordance with University regulations
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