The freshwater ecosystem (Kelana Jaya Lake, Seremban Lake Garden and Kanching Eco Forest Park) of west Peninsular Malaysia was the focus of the study's attempt to offer a current checklist of benthic organisms. Three benthic organisms were identified in the urbanized Kelana Jaya Lake, namely the red-rim melania (Melanoides tuberculata), apple snail (Pomacea sp.), and an Odonata damselfly nymph. Four different species were identified for Seremban Lake Garden: Hydrilla verticillata, Viviparus sp., nymph of Odonata, and Macrobrachium sp. The freshwater prawn Macrobrachium was the only genus identified for Kanching Eco Forest Park. Our attempts to promote aquatic ecosystem management and conservation in Malaysia can use the checklist of benthic creatures from the freshwater ecosystems as a continuous baseline for future reference.

Keywords: benthic organisms, Peninsular Malaysia, aquatic ecosystem

Benthic organisms, including invertebrates and fish, live on the lowest level of the aquatic habitat, usually near the sediments. They serve a role in maintaining the habitat and as a food source for humans and other aquatic animals. Most benthic organisms are detritivores in the food chain. Animal wastes or dead organic matter are consumed and converted into dissolved nutrients for other microorganisms, aquatic plants, or algae.^1–28 Recently, there has been an increase in pollution and environmental degradation due to human activities. Nutrient run-off (eutrophication) is still a recurring problem and has caused the concentrations of heavy metal toxins to increase over the years. The impact of pollution on the benthic communities is detrimental. Algae or phytoplankton consume the excess nutrients. Blooms of harmful algae kill nearby organisms occupying the same habitat. The dead macro and microfauna from the bloom, including the phytoplankton, will be decomposed by aerobic bacteria. Thus, it creates an environment with low oxygen concentrations, and it is unsuitable for other organisms to inhabit.²

Aside from environmental damage, heavy metal pollution is believed to affect the development of benthos. For instance, shell deformities in benthos, such as marine bivalves, have been observed. Bivalves are filter feeders; they can absorb pollutants and surrounding particles to keep the water clean and support the growth of other organisms. Filter-feeding bivalves can be a bioindicator species.³ They are sensitive to environmental change yet resilient to pollution and abundant in numbers.⁴ Therefore, benthic organisms are extensively studied for the better health of the environment. Studying benthic organisms in the aquatic ecosystem of Peninsular Malaysia will provide an essential understanding of the health of ecosystems and their diversity. This study aims to investigate the presence and provide the latest checklist of benthic organisms in aquatic habitats of freshwater ecosystems of west Peninsular Malaysia.

Observational studies and samplings for benthic organisms were conducted from November to December 2022 at the freshwater ecosystems (Kelana Jaya Lake, Seremban Lake Garden and Kanching Eco Forest Park). They were collected by scooping around the sediments with a long butterfly net and then placed on a scale cutting mat. Photographs were then taken using a smartphone camera. Some photographs were taken without the cutting mat due to the mat not being available. Subsequently, the benthos were immediately released to the same place where they were collected. The samples were identified following the publications of Morni et al.,⁵ Dance⁶ iNaturalist⁷ Palomares and Pauly⁸ and by comparing the shell characteristics and identification described by Perez et al.⁹ Each species name was then cross-checked with the WoRMS Editorial Board¹0 to ensure the taxa used in this study are accurate and updated Table 1.

Tables 2 to 9 show the photographs and identification of each collected benthos. The identification of benthos was done to the lowest taxonomic level possible. Also included in the tables were their trophic levels, habitats, sizes, and conservation status based on IUCN.¹¹

Scientific name: Melanoides tuberculata
Family: Thiaridae
Trophic level: Endobenthos
Benthos classification by size: Macrobenthos
Benthos classification by type: Zoobenthos
Benthos classification by location: Endobenthos
Size: + 2 cm
IUCN status: Least concern

Table 2 Red-rim melania Melanoides tuberculata collected from Kelana Jaya Lake

There were, however, some limitations to this study. Firstly, some benthos, such as damselflies, were caught in their juvenile stage, and their organisms were found dead. Therefore, species-level identification was made just by observation. Secondly, mud or algae accumulation on the bodies of benthos may alter the appearance and colour of the benthos. Therefore, it is difficult to identify each species down to its lowest taxonomic level. Thirdly, the size of each organism may not be accurate as some photographs were taken without the scale cutting mat, and the measurement was done by comparing it to the length of the index finger.

Three distinct species of benthic animals were found at Kelana Jaya Lake. They were the red-rim melania Melanoides tuberculata (Table 2), damselfly nymph of Odonata (Table 3), and apple snail Pomacea sp. with their eggs (Table 4). Kelana Jaya Lake is a large lake in the city where there are lots of human activities nearby the lake. The water is exceptionally green, and litter, such as plastic bottles, were observed during sampling. The red-rim melania is known for its burrowing nature and is native to Malaysia.¹²

Order: Odonata
Suborder: Zygoptera
Trophic level: Secondary consumers
Benthos classification by size: Macrobenthos
Benthos classification by type: Zoobenthos
Benthos classification by location: Hyperbenthos
Size: + 2 cm

Table 3 Damselfly nymph of Odonata collected from Kelana Jaya Lake

Scientific name: Pomacea sp.
Family: Ampullarioidea
Trophic level: Primary consumer
Benthos classification by size: Macrobenthos
Benthos classification by type: Zoobenthos
Benthos classification by location: Endobenthos
Size: + 1 cm
IUCN red list: Least concern

Table 4 Apple snail Pomacea sp. and their eggs (right photo) spotted at Kelana Jaya Lake

Identifying the damselfly nymph to the lowest possible level was impossible at this stage of its life cycle. Also, the IUCN red list status was not confirmed because the species was not identified. The Odonata larvae live in freshwater. Depending on the species and food availability, its larval stage takes two weeks to a few months.¹³ Two of the most invasive species in the genus Pomacea (P. canaliculata and P. maculata) have been recorded in Selangor.¹⁴ By only visual observation and without a genetic analysis, the authors have difficulty identifying the correct species.

Seremban Lake Garden consists of multiple small turbid lakes. There were four distinct species found in this urban lake, namely water thyme Hydrilla verticillata (Table 5), river snail Viviparus sp. (Table 6), nymph of Odonata (Table 7) and freshwater prawn Macrobrachium sp. (Table 8). Hydrilla verticillata can be found throughout Malaysia, India, Sri Lanka, China and the USA up to an altitude of 610 m in water, including lakes, ponds, rivers, streams and marshes.¹⁵ It was present in the deserted brown water of the Seremban Lake, where no benthic life form was collected. According to Kritzberg et al.,¹⁶ brown water is a sign of low productivity and biodiversity of phytoplankton communities due to lesser light reaching into the water. While in other moving lakes, river snails (Viviparus sp.) were found. Viviparus is a genus of giant freshwater snails with a gill and an operculum, an aquatic gastropod in the family Viviparidae, the river snails.⁷ Another spotted organism, a dragonfly nymph, has a broad body compared to a damselfly nymph and has short appendages instead of the long fin-like gills seen in a damselfly nymph. The common dragonflies were usually found in ponds and drainages in the countryside.¹³ A group of freshwater prawn Macrobrachium sp. was caught while scooping around the lake. Ng et al.¹⁷ identified two species of Macrobrachium prawns at UKM Lake, another turbid lake, about 40 km north of Seremban.

Scientific name: Hydrilla verticillate
Family: Hydrocharitaceae
Trophic level: Producer
Benthos classification by size: Macrobenthos
Benthos classification by type: Phytobenthos
Benthos classification by location: Hyperbenthos
Size: 12.5 cm in height.
IUCN red list: Least concern

Table 5 Water thyme Hydrilla verticillata collected from Seremban Lake Garden

Scientific name: Viviparus sp.
Family: Viviparidae
Trophic level: Primary consumer
Benthos classification by size: Macrobenthos
Benthos classification by type: Zoobenthos
Benthos classification by location: Endobenthos
Size: 2.2 cm
IUCN red list: Either Least concern or Data deficient

Table 6 River snail (Viviparus sp.) collected from Seremban Lake Garden

Order: Odonata
Suborder: Anisoptera
Trophic level: Secondary consumer.
Benthos classification by size: Macrobenthos
Benthos classification by type: Zoobenthos
Benthos classification by location: Hyperbenthos
Size: + 2 cm

Table 7 Dragonfly nymph (Order Odonata) collected from Seremban Lake Garden

Scientific name: Macrobrachium sp.
Family: Palaemonidae
Trophic level: Primary consumer
Benthos classification by size: Macrobenthos
Benthos classification by type: Zoobenthos
Benthos classification by location: Hyperbenthos
Size: 4 cm for length of body.
IUCN red list: Mostly categorized as Least concern

Table 8 Freshwater prawn Macrobrachium sp. collected from Seremban Lake Garden

The Kanching Eco Forest Park (Taman Eko Rimba Kanching) is located in Rawang, Selangor, and is renowned for its seven levels of waterfalls and pools connected to the Kanching River. Two freshwater prawns, Macrobrachium spp., were found in this forest park (Table 9). The authors, however, were unable to differentiate the species. According to Ng and Choy,¹⁸ there were 15 species of freshwater prawns under the genus Macrobrachium presented in Peninsular Malaysia. Only the prawns were collected from different levels of pools. The lack of gastropods and other benthos could be due to the water velocity. The water in the pool was clear but flowing extremely fast. According to Koehl,¹⁹ organisms that live anchored to the substratum, basically benthos, the force of flowing water may stress them and cause deformity.

Scientific name: Macrobrachium spp.
Family: Palaemonidae
Trophic level: Primary consumer
Benthos classification by size: Macrobenthos
Benthos classification by type: Zoobenthos
Benthos classification by location: Epibenthos
Size: 2 to 4 cm
IUCN red list: Mostly categorized as Least concern

Table 9 Freshwater prawns Macrobrachium spp. collected from Kanching Eco Forest Park

This preliminary study is conducted to provide an inventory of benthic organisms found in freshwater ecosystems (Kelana Jaya Lake, Seremban Lake Garden and Kanching Eco Forest Park). Three different kinds of benthic organisms were found in the inhabited Kelana Jaya Lake. Four distinct species were found in Seremban Lake Garden, while the sole genus discovered in Kanching Eco Forest Park was Macrobrachium. Finally, this preliminary study's list of benthic organisms can serve as baseline data for ongoing efforts to enhance aquatic ecosystem management and conservation in Malaysia.

None.

The authors declare no conflict of interest.

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