Materials and Methods
This study was conducted in two streams of second
order flowing into Temengor Reservoir, the Sungai
Enam and Sungai Telang. Presence of sand-bed, bedrock,
sand-bedrock, cobbles, pebbles, logs and woody debris,
characterized these streams. Streams were chosen have
into account access conditions and the absence of previous studies.
In the streams, all pools along a transect of 500 m
from the river mouth were numbered and used in pool
selections for stream stratification and sampling purposes.
All numbered pools were stratified evenly into three zones,
namely, the upper, middle and lower zones. Stratified and
random sampling designs were adopted for this study,
where two pools were randomly selected from each zone
in each sampling effort.
A portable electro-fisher with voltage ranging from
100 V to 1100 V and pulsed DC option, together with scoop
nets were used to catch fish in this study. The electro-fisher operator and two assistants explored each selected pool
from one end to another three times. Captured fish were
placed in a bucket filled with stream water to keep the fish
alive. The fish were then identified and measured for total
length and weight before being released back into the pool
of origin. Unidentified and representative specimens of
each species were preserved in 10% formalin for voucher
collection and species identification in the laboratory.
Species taxonomy, identification and classification system
follow Ikan air tawar di Semenanjung Malaysia (Freshwater
fishes of Peninsular Malaysia) by Mohsin and Ambak (1991)
as main reference and Kottelat et al. (1993), Rainboth
(1996) and Chong et al. (2010) as additional references.
Check spellings, authorships and dates of publication of
each species name were validated consulting Eschmeyer
and Fricke (2011). Voucher specimens were deposited
at the School of Biological Sciences, Universiti Sains
Malaysia. Fishing permit for this study has been approved
by Fisheries Department of Perak State.
Diversity and evenness were calculated based on
Shannon-Weiner diversity indices as given by Krebs (1999),
whereas species rarity was calculated following Othman
et al. (2002), which was based on an adaptation from the
guidelines used for birds by Wong (1985). According to the
guidelines, a species considered as ‘locally rare’ whenever
the total individual of the respective species is less than
2% of the total catch in the respective area.
All fish data from the studies conducted in Sungai
Enam from 1993 [Ismail and Sabariah 1995; Md. Akhir
1999 (unpublished data); Berryhill 2003 (unpublished
data)] to the most recent sampling in 2011 were compiled
and compared.
Results and Discussion
Twenty-one fish species comprising nine families were
recorded during the study. Nineteen species were recorded
in Sungai Telang with 11 species classified as “locally rare”,
whereas in Sungai Enam, 11 species were recorded with
nine species classified as “locally rare” (Table 1). Shannon-
Wiener diversity and evenness indices were higher in
Sungai Telang (2.74; 0.64) compared to Sungai Enam (1.69;
0.49). Both streams showed an ascending trend of diversity
index from the upper zone to the middle and lower zones.
In Sungai Enam, the diversity indices were 1.43, 1.45 and
1.99, respectively, whereas the diversity indices in Sungai
Telang were 2.46, 2.59 and 2.88, respectively.
The ascending trend of diversity index from the upper
to the lower zones in both streams indicates community
expansion by species addition, which also reflects the
function of stream order, as suggested by Horton (1945)
and Strahler (1957). According to Cowx and Welcomme
(1998), the number of fish species and abundance in
streams depends on four undamaged riverine interactive
pathways, which are temporal dimension, longitudinal
pathways, lateral interactions and vertical interactions.
Species distribution by stream zones showed that only
four species were present in all zones in both streams,
namely Devario regina (Fowler 1934), Neolissochilus
soroides (Duncker 1904), Poropuntius smedleyi (de
Beaufort 1933) and Puntius binotatus (Valenciennes
1842) (Table 1). In Sungai Enam, the total number of
individuals recorded in the upper, middle and the lower
zones were 352 (5 species), 366 (5 species) and 278 (10
species), respectively. In Sungai Telang, the total number
of individuals recorded was 348 (14 species), 458 (13 species) and 136 (14 species) respectively. The differences
in the number of species from the upper zone to the
lower zone between Sungai Enam and Sungai Telang were
probably due to stream slope and waterfalls. According to
Schlosser (1982), the changes in fish community structure
and function along the physical gradients support the
qualitative contention of the stream continuum concept,
i.e. “Consistent shifts in community organization are
associated with spatial or temporal changes in resource
availability, channel morphology and flow regime”. A shift
from shallow, temporally variable habitats to deeper,
relatively stable areas in conjunction with seasonal
variation resource availability, are major proximate factors
associated with changes in fish community organization
(Schlosser 1982).
In Garonne River, Spain, Santoul et al. (2005), found
that the richness of fish species increased progressively
from upstream to downstream, and the longitudinal
patterns of fish assemblages partitioned the river into
clear biogeographic areas. Jansen et al. (1999) agreed that
a shift in numbers and species composition between sites
could be partially related to differences in the available
habitat. However, in the upper Saône River in France,
Grenouillet et al. (2004) found that only the stream
width and gradients significantly influenced local species
richness among the different local habitat variables. These
studies showed that the shape and the stream topography
affect longitudinal distribution of fish species, as it could
be a barrier for fish migration.
Migratory behavior is another means of fish movements
along stream gradients. However, barriers such as high
waterfalls and strong currents can restrict this. The absence
of Hampala macrolepidota Kuhl and Van Hasselt 1823 and
Osteochilus vittatus (Valenciennes 1842) in the upper zone of Sungai Enam compared to Sungai Telang suggests that
the migration process of these species to the upper zone
of Sungai Enam was restricted due to certain barriers,
such as the gradient slope and water velocity. Wootton
(1992) stated that in stream and river environments, high
waterfalls or rapids act as barriers, which prevent fish
from migrating upstream. According to Yap (2002), fish
diversity and composition similarity is often correlated
with the morphology of the river basins, which were
formed through geological processes. In Sungai Enam,
the height between pools varies and the waterfalls can be
more than five meters high. Besides, having steep ends
and stream slope, the geographical condition of this area
also produces strong currents. These conditions present
significant barriers for fish attempting to migrate to the
upper zone. The Sungai Telang, is steeper and differences
in height conditions between the pools are smaller, which
enables easier fish migration to the upper zone.
Based on studies conducted by Ismail and Sabariah
(1995), Md. Akhir (1999; unpublished data), and Berryhill
(2003; unpublished data), this study and the latest
inventory check in July 2011, the total number of fish
species recorded in Sungai Enam from 1993 to 2011
is 28 species, whereas the total number of fish species
recorded in Sungai Telang is 27 species (Table 2). Among
the 28 species in Sungai Enam, only four species were
consistently captured in all studies, these are D. regina,
N. soroides, P. smedleyi and O. vittatus. The first three
species are common species in both Sungai Enam and
Sungai Telang and are good indicator species for stream
health due they require pristine and clear water quality for
survival (Rainboth 1996).
The presence of the three common species in both
headwaters streams during all studies conducted indicates
that both headwaters are healthy and function as sources
for clean water, nutrient supplies and fish recruits for
the reservoir. The streams’ physical and environmental
characteristics, flow regimes, the four riverine interactive
pathways and the ability of the fish species to migrate and
to resist the strong currents determine species diversity
and distribution along the gradients. The dynamics of
the species richness throughout all inventory studies
indicates that these rivers also serve as breeding ground
for Hampala macrolepidota and Osteochilus vittatus. This
type of study should be carried out for other headwater
streams to ensure the sustainability of such ecosystem and
fisheries importance