An annotated checklist of fish fauna of Bukit Merah Reservoir and its catchment area , Perak , Malaysia

The fish fauna was surveyed at Bukit Merah Reservoir of Perak (one of the oldest reservoir in Peninsular Malaysia) and its catchment areas. A total of 47 species from 19 families were recorded: 38 fish species were recorded from eight sampling stations located in selected tributaries (lotic zone), while another 25 fish species were recorded in the reservoir itself (lentic zone). Based on a combination of previously published checklists and the present survey, a total of 76 fish species were recorded at Bukit Merah Reservoir. Out of these species, 25 fish species from this survey were new records. Most of the new records were found in the catchment area of the river basin. The presence of two alien species, Oreochromis niloticus and Clarias gariepinus , should be noted as these species could affect the population of native species.


Introduction
The freshwater ecosystems of Peninsular Malaysia can be divided into lentic and lotic water bodies (Mohsin and Ambak 1983).Bukit Merah Reservoir (BMR), which was built in 1902 and operated in 1906 is one of the oldest man-made reservoirs in Peninsular Malaysia, and its water catchment is an example where these two types of water bodies can be found.Located in the district of Kerian, these lentic and lotic water bodies form contiguous irrigation and drainage canals in the northwestern part of Perak State.There are two main catchment areas that are located upstream of the reservoir, namely the Kurau and Merah rivers (Figure 1).The catchment areas that are located in the eastern part of the reservoir provide more than 80% of stream networks and watershed land areas (Wipfli et al. 2007).Water from the reservoir is channeled out through two outlet canals, i.e.Besar and Selinsing canals (Ismail and Najib 2011;DID 2012).According to Department of Irrigation and Drainage of Kerian (DID 2012), the main function of BMR is to provide irrigation water for double cropping to 24,000 Ha of paddy fields under the Kerian-Manik River Project.The reservoir is also recognized as a sanctuary for a commercially valuable fish, the Asian Arowana, Scleropages formosus.
There have been inventories of the fishes from the reservoir since 1930s.Most of the available literature focuses on fish inventories from Kurau River basin to the BMR but there is lack information about fish inventories in tributaries within the catchment area.As reported by Wipfli et al. (2007), the upper and lower streams are the most important freshwater resources that support the biological productivity and species richness of the reservoir.Thus, this study provides an extensive fish species checklist together in the present study and later will be compared to earlier surveys by de Beaufort (1933), Abstract: The fish fauna was surveyed at Bukit Merah Reservoir of Perak (one of the oldest reservoir in Peninsular Malaysia) and its catchment areas.A total of 47 species from 19 families were recorded: 38 fish species were recorded from eight sampling stations located in selected tributaries (lotic zone), while another 25 fish species were recorded in the reservoir itself (lentic zone).Based on a combination of previously published checklists and the present survey, a total of 76 fish species were recorded at Bukit Merah Reservoir.Out of these species, 25 fish species from this survey were new records.Most of the new records were found in the catchment area of the river basin.The presence of two alien species, Oreochromis niloticus and Clarias gariepinus, should be noted as these species could affect the population of native species.

SAU
5°5′25.5″N 100°51′10.70″E A river with low gradient river banks.A clear, shallow to moderate river depth, fast flowing water and partially shaded by the riparian vegetation.The river is surrounded by rural areas.The main substrates for this river are sand, gravel and cobble.

SKU
4°54′17.4″ N 100°49′59.9″E A moderate size hillstream river with low gradient river banks.It is located in hilly areas with fruit orchards nearby.This river is relatively fast flowing with the main substrates are boulder and cobble.This river is partially shaded by riparian vegetations such as Koompassia malaccensis.

SJL
5°0′49.8″N 100°48′37.4″E A large hillstream river with moderate gradient river banks.It has very fast flowing water with substrate dominated by sand.The grass is the main vegetation.

SMD
5°5′53.4″N 100°43′13.20″E This is a small river located within the Pondok Tanjung Forest Reserve.The river is moderate in water depth with sand as a substrate.

SAD
5°0′38.5″N 100°43′51.60″E The river has been altered to become steep of river banks, deep and fast flowing water This water surface is exposed directly to sunlight.The main substrate is sand and only grass is found to be the main vegetation.

SKD
5°0′42.6″N 100°43′56.40″E The river has been altered to become wide, moderate flowing water and near to SAD.Moderate river banks and the main substrates are sand and gravel.The SAD and SKD are adjacent to the railway.
This station is located at the inlet of Kurau River Basin.
Table 1.General characteristics of sampling stations with coordinates in Bukit Merah Reservoir.
ethanol for long-term storage, given a catalogue number and housed in the Museum of Zoology of the School of Biological Sciences, Universiti Sains Malaysia.
The checklist is arranged in systematic order following Nelson (2006).Under the material examined, the following data were presented: Universiti Sains Malaysia Fish Collection acronym (USMFC) with its catalogue number, number of specimens examined, and standard length (SL) in millimeters (mm) or range of standard length, locality and collector.The fish data from the current studies were compared to and combined with studies from de Beaufort (1933), Tweedie (1936), Herre and Myers (1937), Yap (1982), DoF (1993) and Arai et al. (2012) to provide a more comprehensive view of the fish species diversity of the studied locality.

Results
A total of 47 species from 19 families were recorded during the study period.Thirty-eight species were recorded in the rivers and streams of the catchment area (lotic zone) while 25 species were collected in the reservoir (lentic zone).The spatial fish diversity shows an ascending trend from upstream to downstream in the rivers, especially in the Kurau and Merah rivers, where the number of species increased from six and 11 to 17 and 12, respectively.However, the trend was not occurred in the Ara River where the number of species at the upstream of the river was higher than the downstream (15 to 9).Of the 47 species, only 22 were recorded in the lotic zone:  2).Based on the surveys conducted by de Beaufort (1933), Tweedie (1936), Herre and Myers (1937), Yap (1982), DoF (1993), Arai et al. (2012) and the present study, the total number of fish species and family recorded in this area were 76 and 25, respectively.Our survey added 25 fish species this list.

Discussion
The total number of fish species from the present study had higher than the previous studies (47 fish species) but lower than the total number of species recorded in the State of Perak (128 fish species) (Yusoff et al. 2006;Chong et al. 2010).Among all fish species, cyprinid fishes are the most dominant family in both lentic and lotic areas.Many species belonging to this family are naturally found throughout tropical and subtropical of southern and southeastern Asia (Zakaria-Ismail 1994;Nguyen and De Silva 2006;Chong et al. 2010).Twenty-two fish species recorded from previous surveys were frequently encountered in our surveys, but we did not encounter 29 of the previously reported species in our surveys, including the type locality of two species from this reservoir, Lepidocephalichthys furcatus and Macrognathus perakensis (de Beaufort 1933;Herre and Myers 1937).
In Ara River, the heterogeneous habitat in the upper reaches of this river (SAU) contributes to the species richness instead of homogeneous habitat in the SAD.Generally, species richness in Malaysian rivers is correlated with water depth and velocity (Mendelson 1975;Schlosser 1985;Meffe and Sheldon 1988), substrate type, aquatic vegetation and bank cover (Gorman and Karr 1978;Schlosser 1982).In the SAU, the habitat that contains pools, riffles and riparian vegetation including grass provides variable food sources, shelter and diversity of fishes.However, the SAD had been altered from shallow, slow moving water into steep river banks, deep and fast flowing river hence reducing the efficiency of using current sampling gears to collect fishes.The ecotone of the river and reservoir, known as the transitional zone, contributes to the increase in fish diversity due to high abundance of submerged and floating macrophytes that increase spatial heterogeneity and feeding resource availability (Lowe-McConnell 1991;Aliko et al. 2010;Terra et al. 2010).Thus, lotic and lentic species that co-exist and inhabit this zone temporally contributed to the increasing of species richness (Oliveira et al. 2003), and it is assumed that this might have been the case in SKD, SMD and SJD.
There are several factors that influence the discrepancy in the number of species between previous studies and our survey.One such factor is the increase in the area sampled.The previous studies only covered the area between the influxes of the Kurau River into the BMR to the reservoir outlet at the dam, whereas the present study included tributaries within the catchment area, with these new sampling sites significantly contributing to the species richness of the samples.Maximizing sampling efforts by using different sampling gear also helped to increase the catch potential of fish in different habitats.These are the reasons for most of the newly-recorded species being from the catchment area of the reservoir.Among these new records, species such as Devario regina, Glyptothorax siamensis and Channa gachua are known to be restricted to the upper parts of river systems (Johnson 1967); this may explain their absence in previous surveys.
In our study, two alien species were newly recorded from the BMR: Oreochromis niloticus (Nile Tilapia) and Clarias gariepinus (African catfish); Cyprinus carpio (common carp) has also been previously recorded here, but we did not encounter this species.Many alien fish species had been introduced in Malaysia, mainly for aquaculture purposes (Yusoff et al. 2006); these include Barbonymus gonionotus (Indonesian carp), O. niloticus, and C. carpio.In other cases, many local recreational anglers used non-native species such as C. gariepinus as a bait to catch Channa micropeltes for sport.This situation has led to the introduction of alien invasive (Ng and Tan 2010;Ng et al. 2014).The presence of O. niloticus in this reservoir was unknown, although there was a report that it had escaped into the lake from cages in which they were cultured (DoF 1993).Some of the nonnative species such as B. gonionotus and T. pectoralis are well established in local freshwater ecosystems.However, the impacts of O. niloticus and C. gariepinus on local species and their habitats have yet to be established, but their presence should be of concern, because these species have been shown to adversely affect native fish species as alien invasives (Cowx 1997;Nguyen and De Silva 2006;Diana 2009;Ng et al. 2014).The introduced species can deconstruct native freshwater ecologies by disrupting the food chain, outcompeting native species for food, habitat and water quality alterations and the importation of parasites and diseases (Arthington 1991;Diana 2009;Ng et al. 2014).The list of fish species in Bukit Merah Reservoir and its catchment area indicates that limitations in the present sampling techniques may fail to capture some species and there has still some improvements can be made with the use of the appropriate fishing gear that addresses the deficiencies.1. Fish checklist of Bukit Merah Reservoir (BMR) and its catchment area based on presence (+) and absence (-) data by site, and data from (a) de Beaufort ( 1933), (b) Tweedie (1936), (c) Herre and Myers (1937), (d) Yap (1982), (e) DoF ( 1993

Figure 1 .
Figure 1.Locations of sampling stations in Bukit Merah Reservoir and its catchment areas, Perak, Malaysia.