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Introduced aquatic herpetofauna of Singapore's reservoirs
Abstract
Sixteen species of introduced or alien aquatic amphibians and reptiles have been recorded from Singapore's Public Utilities Board reservoirs. Their presence in the wild state is largely due to members of the public abandoning their pets, or releasing animals to gain spiritual merit (fang sheng). The ban imposed by the Agri-Food and Veterinary Authority on the sale of most species of amphibians and reptiles will probably help to restrict the diversity of alien animal species in Singapore. However, the continued availability of hatchling red-eared terrapins in pet shops and live Chinese softshell turtles and American bullfrogs in markets does little to reduce the presence of these three alien species in local water bodies.
... Subsequent publications suggested that the number was even greater, for example, 2 molluscs, 2 freshwater fish and 1 crustacean species were added to the list between 2006 and 2009 (Clements et al. 2006, Ahyong & Yeo 2007, Tan & Lim 2008, Ng et al. 2009). Most recently, a series of reviews and species checklists recorded as many as 98 exotic freshwater species in Singapore, in cluding 64 species of fishes, 24 herptiles, 6 molluscs and 4 decapod crustaceans, with many of these be lieved to have originated from ornamental trade im ports (Ng & Lim 2010, Ng & Tan 2010, Yeo 2010, Yeo & Chia 2010. ...
... Owing to the low abundance and unlikely establishment success in acid waters, it may be too early to state that the current Cherax quadricarinatus presence and distribution constitutes an immediate danger for Singapore's natural freshwater environment. According to their geographic distribution, the C. quadricarinatus populations are still restricted to artificial lakes, which already support high numbers of exotic species (e.g. of freshwater fish species, 50% are non-indigenous; Ng et al. 1993, see also Ng & Lim 2010, Ng & Tan 2010, Yeo 2010, Yeo & Chia 2010. Presently, the different abiotic conditions between the reservoirs (relatively alkaline waters) and the natural forest streams and swamp in the nature reserves (relatively acidic waters) seem to provide a sufficient barrier to a range expansion of C. quadricarinatus into Singapore's natural freshwater systems. ...
... Owing to this habitat alteration, the reservoirs are 'exotic species heavens' as they provide a novel environment, which differs from the native, acid forest to which stream-inhabiting species are adapted (e.g. Ng et al. 1993, Ng & Lim 2010, Ng & Tan 2010, Yeo 2010, and in which invasions appear to be more likely because empty niches are available (Hierro et al. 2005, Paavola et al. 2005. The reservoirs might also more closely resemble the native ecosystems of exotic species, helping them overcome the 'environmental filter' (Richardson et al. 2000) and favouring subsequent establishment (Kolar & Lodge 2002, Hayes & Barry 2007. ...
The ornamental trade is one of the major vectors of freshwater animal species transloca- tion worldwide. The Australian redclaw crayfish Cherax quadricarinatus was brought into Singapore through the trade and culture of aquarium specimens during the late 1980s. From 2000 to the present, redclaw crayfish have been observed in at least 3 of Singapore’s 13 reservoirs, including 2 inland reservoirs in the Central Catchment Nature Reserve (CCNR). The current paper presents the first in situ population data of feral C. quadricarinatus populations originating from ornamental trade and includes updated distribution records in Singapore based on recent surveys and museum samples. We report a C. quadricarinatus range expansion in 2 additional reservoirs (1 coastal and 1 inland), and the presence of multiple size cohorts confirms the establishment of reproducing populations in 2 coastal reservoirs and 1 CCNR reservoir. This is alarming as the current distribution borders Singa- pore’s oldest and arguably most important nature reserve (Bukit Timah Nature Reserve: BTNR) and encircles the single remaining substantial freshwater swamp forest in the country (Nee Soon). The Nee Soon swamp forest and BTNR have extremely high conservation value as both areas together harbour the richest native freshwater fauna and flora of the island. Therefore, any range expansion of C. quadricarinatus in Singapore may have severe impacts on its native freshwater fauna and demands immediate attention. As C. quadricarinatus is one of the many invasive freshwater species occurring from the aquarium trade in Singapore, we argue that trade control might prevent further establishment of ornamentals.
... Despite the similarity in that trend, the introduction pathways of anuran NIS appear to be unique among the nonindigenous aquatic vertebrates here. While the pet trade has been linked to the introductions of many freshwater fishes (Ng & Tan, 2010) and reptiles (Ng & Lim, 2010) into Singapore freshwater habitats, there does not seem to be as strong a connection with the pet trade for anurans (see later: Introduction pathways under Lithobates catesbeianus). Only one amphibian species, White's tree frog (Litoria caerulea) from Australia and New Guinea, can legally be sold as a pet in Singapore (Agri-Food & Veterinary Authority Singapore, 2011), but it has not been recorded outside of pet shops. ...
... Local records have mostly been of individual adults or groups of juveniles. Owing to the ease of buying live Lithobates catesbeianus, these records were likely a result of releases by religious devotees seeking to gain spiritual merit or were unwanted bait discarded by anglers (Ng & Lim, 2010). The species does not appear to be breeding outside the frog farm as no eggs or tadpoles have been recorded to date (Ng & Lim, 2010). ...
... Owing to the ease of buying live Lithobates catesbeianus, these records were likely a result of releases by religious devotees seeking to gain spiritual merit or were unwanted bait discarded by anglers (Ng & Lim, 2010). The species does not appear to be breeding outside the frog farm as no eggs or tadpoles have been recorded to date (Ng & Lim, 2010). ...
The statuses of the non-indigenous frogs in Singapore are reviewed. Out of the 28 species of anurans known in Singapore, four are non-indigenous: Hylarana guentheri (Boulenger), Kaloula pulchra Gray, Lithobates catesbeianus (Shaw), and Microhyla fissipes Boulenger. The introduction pathways of the frogs are discussed, along with their status, distribution, impacts, and management issues with regard to Singapore.
... Subsequent publications suggested that the number was even greater, for example, 2 molluscs, 2 freshwater fish and 1 crustacean species were added to the list between 2006 and 2009 (Clements et al. 2006, Ahyong & Yeo 2007, Tan & Lim 2008, Ng et al. 2009). Most recently, a series of reviews and species checklists recorded as many as 98 exotic freshwater species in Singapore, in cluding 64 species of fishes, 24 herptiles, 6 molluscs and 4 decapod crustaceans, with many of these be lieved to have originated from ornamental trade im ports (Ng & Lim 2010, Ng & Tan 2010, Yeo 2010, Yeo & Chia 2010. ...
... Owing to the low abundance and unlikely establishment success in acid waters, it may be too early to state that the current Cherax quadricarinatus presence and distribution constitutes an immediate danger for Singapore's natural freshwater environment. According to their geographic distribution, the C. quadricarinatus populations are still restricted to artificial lakes, which already support high numbers of exotic species (e.g. of freshwater fish species, 50% are non-indigenous; Ng et al. 1993, see also Ng & Lim 2010, Ng & Tan 2010, Yeo 2010, Yeo & Chia 2010. Presently, the different abiotic conditions between the reservoirs (relatively alkaline waters) and the natural forest streams and swamp in the nature reserves (relatively acidic waters) seem to provide a sufficient barrier to a range expansion of C. quadricarinatus into Singapore's natural freshwater systems. ...
... Owing to this habitat alteration, the reservoirs are 'exotic species heavens' as they provide a novel environment, which differs from the native, acid forest to which stream-inhabiting species are adapted (e.g. Ng et al. 1993, Ng & Lim 2010, Ng & Tan 2010, Yeo 2010, and in which invasions appear to be more likely because empty niches are available (Hierro et al. 2005, Paavola et al. 2005. The reservoirs might also more closely resemble the native ecosystems of exotic species, helping them overcome the 'environmental filter' (Richardson et al. 2000) and favouring subsequent establishment (Kolar & Lodge 2002, Hayes & Barry 2007. ...
The ornamental trade is one of the major vectors of freshwater animal species translocation worldwide. The Australian redclaw crayfish Cherax quadricarinatus was brought into Singapore through the trade and culture of aquarium specimens during the late 1980s. From 2000 to the present, redclaw crayfish have been observed in at least 3 of Singapore’s 13 reservoirs, including 2 inland reservoirs in the Central Catchment Nature Reserve (CCNR). The current paper presents the first in situ population data of feral C. quadricarinatus populations originating from ornamental trade and includes updated distribution records in Singapore based on recent surveys and museum samples. We report a C. quadricarinatus range expansion in 2 additional reservoirs (1 coastal and 1 inland), and the presence of multiple size cohorts confirms the establishment of reproducing populations in 2 coastal reservoirs and 1 CCNR reservoir. This is alarming as the current distribution borders Singapore’s oldest and arguably most important nature reserve (Bukit Timah Nature Reserve: BTNR) and encircles the single remaining substantial freshwater swamp forest in the country (Nee Soon). The Nee Soon swamp forest and BTNR have extremely high conservation value as both areas together harbour the richest native freshwater fauna and flora of the island. Therefore, any range expansion of C. quadricarinatus in Singapore may have severe impacts on its native freshwater fauna and demands immediate attention. As C. quadricarinatus is one of the many invasive freshwater species occurring from the aquarium trade in Singapore, we argue that trade control might prevent further establishment of ornamentals.
... Alien species are sometimes intentionally spread for economic reasons, such as agriculture, biological control, and pet trade (Chiaverano et al., 2014;Ng & Lim, 2010). In these cases, human history can be a useful tool to help identifying and explaining translocation events. ...
... Until recently, Taiwan province was one of the greatest bullfrog producers and exporters of the world, being the source of many introductions in Southeast Asia. Some of these introductions happened in Singapore (from the 1980s to present) (Ng & Lim, 2010);Indonesia (1984, Indo Prima Bullfrogs' owner, personal communication); and Malaysia (Hardouin, 1997), which was one of the sources for the Cambodian population (Neang, 2010). ...
International socioeconomic relationships form the background that underlies the history of invasive species. Species with economic value, such as the North American bullfrog (Lithobates catesbeianus), are more likely to become internationally distributed and to be subsequently introduced to non-native areas and, consequently, become more difficult to control. Using population genetics methods, we investigated the invasion pathways, the connectivity among clusters in different countries and the native population of origin of globally introduced bullfrog populations. Throughout the analysis of seven microsatellite nuclear loci, one fragment of the mitochondrial cytochrome b locus, and historical information, four main lineages were identified and analyzed along with previous findings. This species’ capability to colonize several countries from few starting lineages highlights the necessity to control new propagule pressure to ensure successful management programs, as high inbreeding and bottleneck effect seem not to diminish the invasive success of this species. There is a consensus between markers that most areas of South America belong to the same genetic population while populations in Asia have a more complex history of introduction.
... Singapore is mainly regarded as an import and re-export country (Nijman, Todd, & Shepherd, 2012) and was the main regional reptile importer between 1998-2007 (Nijman, 2010). In contrast to Thailand, over 20 alien reptile species were present in Singapore in 2010 (Ng & Lim, 2010;Yeo & Chia, 2010). Of these species, only four were considered established (Calotes versicolor, Pareas margaritophorus, Siebenrockiella crassicollis and Xenochrophis vittatus); with I. iguana only known from a few recordings (Chua, 2007;Yeo & Chia, 2010). ...
... Following interviews, we identified the likely source of these invasions to be pet-trade animals that either escaped or were intentionally released by owners or unsecurely exhibited in recreational parks, consistent with other introductions of this species (Kraus, 2009). Besides the release of pet I. iguana due to their size, another motive can be fang sheng; the Buddhist act of releasing live animals believed to build spiritual merit (Agoramoorthy & Hsu, 2005;Ng & Lim, 2010). As I. iguana natively occurs in sub-tropical and tropical biomes physically and climatically similar to those found throughout Southeast Asia (Olson, Dinerstein, Wikramanayake, & Burgess, 2001), we expect continued spread and growth of these alien populations in the absence of mitigation actions. ...
The popularity of the Common Green Iguana (Iguana iguana) as a pet has contributed to its global occurrence as an invasive alien species. Early detection and control of alien I. iguana populations is necessary to prevent the need for large and financially demanding eradication actions. Here, we first collated information from digital footage and interviews regarding sightings of free roaming I. iguana specimens in Singapore and Thailand. We use this information to report and discuss an ongoing invasion with early stage establishment being facilitated by release of pets and escape from recreational parks, as well as the resulting conservation implications. Using species-distribution modeling to assess the potential distribution in Southeast Asia, we identify large regions with suitable habitat that could aid the expansion of these alien populations in the absence of future control measures. In addition, given the availability of suitable habitat throughout the Philippine archipelago and its high number of imported iguanas and within-country trade, we call for awareness of future alien I. iguana populations in the Philippines. Next, the alien population in Singapore is of additional concern given that the excellent swimming capacity of I. iguana allows it to reach neighboring Sumatra and > 3,000 islands of the Indonesian Riau archipelago. Finally, we report I. iguana sightings in Hong Kong and Peninsular Malaysia. We provide strategy recommendations for implementing mitigation efforts and to halt future release and spread in order to prevent negative biodiversity impacts associated with a large invasive alien I. iguana population.
... Singapore is mainly regarded as an import and re-export country (Nijman, Todd, & Shepherd, 2012) and was the main regional reptile importer between 1998-2007 (Nijman, 2010). In contrast to Thailand, over 20 alien reptile species were present in Singapore in 2010 (Ng & Lim, 2010;Yeo & Chia, 2010). Of these species, only four were considered established (Calotes versicolor, Pareas margaritophorus, Siebenrockiella crassicollis and Xenochrophis vittatus); with I. iguana only known from a few recordings (Chua, 2007;Yeo & Chia, 2010). ...
... Following interviews, we identified the likely source of these invasions to be pet-trade animals that either escaped or were intentionally released by owners or unsecurely exhibited in recreational parks, consistent with other introductions of this species (Kraus, 2009). Besides the release of pet I. iguana due to their size, another motive can be fang sheng; the Buddhist act of releasing live animals believed to build spiritual merit (Agoramoorthy & Hsu, 2005;Ng & Lim, 2010). As I. iguana natively occurs in sub-tropical and tropical biomes physically and climatically similar to those found throughout Southeast Asia (Olson, Dinerstein, Wikramanayake, & Burgess, 2001), we expect continued spread and growth of these alien populations in the absence of mitigation actions. ...
... Subsequent publications suggested that the number was even greater, for example, 2 molluscs, 2 freshwater fish and 1 crustacean species were added to the list between 2006 and 2009 (Clements et al. 2006, Ahyong & Yeo 2007, Tan & Lim 2008, Ng et al. 2009). Most recently, a series of reviews and species checklists recorded as many as 98 exotic freshwater species in Singapore, in cluding 64 species of fishes, 24 herptiles , 6 molluscs and 4 decapod crustaceans, with many of these be lieved to have originated from ornamental trade im ports (Ng & Lim 2010, Ng & Tan 2010, Yeo 2010, Yeo & Chia 2010). Cherax quadricarinatus (von Martens, 1868), a large and conspicuously coloured freshwater crayfish of the family Parastacidae, is globally one of the most widely distributed aquaculture and aquarium species (Law - rence & Jones 2002 ). ...
... Owing to this habitat alteration, the reservoirs are 'exotic species heavens' as they provide a novel environment , which differs from the native, acid forest to which stream-inhabiting species are adapted (e.g. Ng et al. 1993, Ng & Lim 2010, Ng & Tan 2010, Yeo 2010), and in which invasions appear to be more likely be cause empty niches are available (Hierro et al. 2005, Paavola et al. 2005). The reservoirs might also more closely resemble the native ecosystems of exotic species , helping them overcome the 'environmental filter' (Richardson et al. 2000) and favouring subsequent establishment (Kolar & Lodge 2002, Hayes & Barry 2007). ...
The ornamental trade is one of the major vectors of freshwater animal species transloca- tion worldwide. The Australian redclaw crayfish Cherax quadricarinatus was brought into Singapore through the trade and culture of aquarium specimens during the late 1980s. From 2000 to the present, redclaw crayfish have been observed in at least 3 of Singapore’s 13 reservoirs, including 2 inland reservoirs in the Central Catchment Nature Reserve (CCNR). The current paper presents the first in situ population data of feral C. quadricarinatus populations originating from ornamental trade and includes updated distribution records in Singapore based on recent surveys and museum samples. We report a C. quadricarinatus range expansion in 2 additional reservoirs (1 coastal and 1 inland), and the presence of multiple size cohorts confirms the establishment of reproducing populations in 2 coastal reservoirs and 1 CCNR reservoir. This is alarming as the current distribution borders Singa- pore’s oldest and arguably most important nature reserve (Bukit Timah Nature Reserve: BTNR) and encircles the single remaining substantial freshwater swamp forest in the country (Nee Soon). The Nee Soon swamp forest and BTNR have extremely high conservation value as both areas together harbour the richest native freshwater fauna and flora of the island. Therefore, any range expansion of C. quadricarinatus in Singapore may have severe impacts on its native freshwater fauna and demands immediate attention. As C. quadricarinatus is one of the many invasive freshwater species occurring from the aquarium trade in Singapore, we argue that trade control might prevent further establishment of ornamentals.
... Subsequent publications suggested that the number was even greater, for example, 2 molluscs, 2 freshwater fish and 1 crustacean species were added to the list between 2006 and 2009 (Clements et al. 2006, Ahyong & Yeo 2007, Tan & Lim 2008, Ng et al. 2009). Most recently, a series of reviews and species checklists recorded as many as 98 exotic freshwater species in Singapore, in cluding 64 species of fishes, 24 herptiles , 6 molluscs and 4 decapod crustaceans, with many of these be lieved to have originated from ornamental trade im ports (Ng & Lim 2010, Ng & Tan 2010, Yeo 2010, Yeo & Chia 2010). Cherax quadricarinatus (von Martens, 1868), a large and conspicuously coloured freshwater crayfish of the family Parastacidae, is globally one of the most widely distributed aquaculture and aquarium species (Law - rence & Jones 2002 ). ...
... Owing to this habitat alteration, the reservoirs are 'exotic species heavens' as they provide a novel environment , which differs from the native, acid forest to which stream-inhabiting species are adapted (e.g. Ng et al. 1993, Ng & Lim 2010, Ng & Tan 2010, Yeo 2010), and in which invasions appear to be more likely be cause empty niches are available (Hierro et al. 2005, Paavola et al. 2005). The reservoirs might also more closely resemble the native ecosystems of exotic species , helping them overcome the 'environmental filter' (Richardson et al. 2000) and favouring subsequent establishment (Kolar & Lodge 2002, Hayes & Barry 2007). ...
The ornamental trade is one of the major vectors of freshwater animal species translocation worldwide. The Australian redclaw crayfish Cherax quadricarinatus was brought into Singapore through the trade and culture of aquarium specimens during the late 1980s. From 2000 to the present, redclaw crayfish have been observed in at least 3 of Singapore's 13 reservoirs, including 2 inland reservoirs in the Central Catchment Nature Reserve (CCNR). The current paper presents the first in situ population data of feral C. quadricarinatus populations originating from ornamental trade and includes updated distribution records in Singapore based on recent surveys and museum samples.
... Like other reptiles, turtles are transported to countries outside of their native range to supply the international pet trade, which sometimes results in individuals either escaping or being released (Stringham and Lockwood 2018;Mantintsilili et al. 2022). Furthermore, some people release captive animals as part of religious acts believed to build spiritual merit (Agoramoorthy and Hsu 2005;Ng and Lim 2010). Turtles also are considered a delicacy in many Asian countries, implicating both turtle farming and imports of live turtles collected from the wild as sources to supply this demand in restaurants (Lau and Haitao 2000;Shiping et al. 2006). ...
... Other I. iguana populations have become established from stowaways in cargo (van den Burg et al., 2020b), construction and horticultural materials (Perry et al., 2021), or over-water dispersal using floating debris (Censky et al., 1998). Furthermore, captive animals may be released as a Buddhist act believed to build spiritual merit (Agoramoorthy and Hsu, 2005;Ng and Lim, 2010). ...
This study investigated the frequency and distribution of reports of free-living green iguanas (Iguana iguana), a Neotropical lizard, in Hong Kong. We found 44 reports of I. iguana, of which 93% were removed from the wild. Thirty-nine reports were records kept by one non-government organization, one report from a government agency, and four reports from community members. Reports were sporadic between 2002 and 2011, but have occurred in every calendar year since 2012, predominately during March, July and October. Report locations were distributed broadly across 16 administrative districts, including heavily developed city areas, indicative of released or escaped pets being the source. Although there was evidence of two individuals living in one locality, we found no major concentrations of reports to indicate established populations. Nevertheless, these data should not be assumed benign since some established populations of I. iguana elsewhere have only become evident following prolonged periods of sporadic reports. It is therefore plausible that emerging reports in Hong Kong may represent a contemporary invasion presently under way. Public reporting of I. iguana plays an important role in preventative invasive species management. However, we also found cases where I. iguana reported as free-living were more likely the same captive I. iguana, highlighting potential errors with community science.
... The disinfectant has been added to the hand soap solutions provided in wet markets and will be constantly topped up with detergents. In Singapore, the availability of living bullfrogs in the market for food uses has caused the escape or the deliberate release in nature, increasing the number of alien species in the national territory (TIN HUI & KELVIN, 2010). The species was first imported into Singapore and observed to be sold as food in the 1980's (NG & LIM, 2010;NG & YEO, 2012). ...
Amphibians are currently facing a global extinction crisis and trade has been identified as a major driver in this decline. Also amphibian trade is known to facilitate the geographic spread of pathogens. Frogs and frog legs are widely regarded as culinary treats in most regions of the world, including Europe, United States, Asia and Aus-tralia. The closures of the Asian animal markets due to the COVID-19 pandemic will have important economic and social repercussions worldwide. There is fear of a return to the illegal and incorrectly controlled frogs market.
... Despite a considerable number of aquatic introductions being attributed to the aquarium trade (e.g. Ng & Tan, 2010;Ng & Lim, 2010;Yeo, 2010), the existing legislation relating to the import of ornamental species is relatively less strict than that of countries like Australia and the USA (Yeo & Chia, 2010;. ...
... Microhyla heymonsi Vogt dark-sided chorus frog (Fig. 24) Reference. Subaraj, 1996: 12 (recorded in February 1996 (Ng & Lim, 2010). ...
The diversity of terrestrial and freshwater, non-avian, vertebrate fauna of Pulau Tekong, an island used almost exclusively by the Singapore Armed Forces, was compiled. Eighteen species of freshwater fishes, 15 of amphibians, 45 species of terrestrial reptiles, and 31 species of terrestrial mammals were recorded. Singapore records of the lizards: Ptychozoon kuhli, Luperosaurus browni, Cyrtodactylus pantiensis and the bat: Murina suilla are known only from Pulau Tekong. The island also has populations of the frogs: Limnonectes paramacrodon and Occidozyga sumatrana; the snakes: Lycodon subcinctus, Boiga jaspidea and Tropidolaemus wagleri; the lizard: Cnemaspis peninsularis, the slow loris: Nycticebus coucang, and the bats: Rhinolophus trifoliatus and Kerivoula hardwickii. These species are locally rare, and otherwise known only from the mature forests of the Central Catchment and Bukit Timah Nature reserves on Singapore Island. Pulau Tekong also supports populations of the leopard cat: Prionailurus bengalensis, the Sunda slow loris: Nycticebus coucang, the Malayan porcupine: Hystrix brachyura and the Sunda pangolin: Manis javanica—small mammals that are regarded to be rare and endangered in Singapore.
... It has been recorded from the Loagan Bunut National Park and Gunung Mulu National Park , both in Sarawak, East Malaysia. In Singapore's Central Nature Reserves, both feral and local populations are reported (Ng and Lim 2010), and the species has been recorded from Nee Soon National Park (Das, pers. obs.). ...
The Southeast Asian Box Turtle, Cuora amboinensis (Family Geoemydidae), is a small (straight carapace length to 25 cm), semi-aquatic turtle, largely restricted to standing water bodies of Southeast Asia, from eastern India to Indonesia and the Philippines. It has four currently recognized subspecies: C. a. amboinensis, C. a. couro, C. a. kamaroma, and C. a. lineata. The species is still relatively common in most of its range, perhaps due to its ability to adapt to a variety of habitats, including rice fields and the vicinity of human settlements. Diet includes both plant and animal matter. The species lays 1–4 large (24–34 x 44–57 mm) eggs with masses of 14–31.5 g. The considerable variation in egg size, incubation period, and reproductive season, as evident from data derived from captive breeding, is thought to be reflective of geographic variation in this widespread turtle species. The species is currently listed as Vulnerable by the IUCN Red List due to its heavy exploitation for the international food, pet, and medicinal trade, and is also included in CITES Appendix II. There is an apparently large illegal trade in the species, and many regional populations appear to be decreasing rapidly, requiring closer monitoring. diStribution. – Bangladesh, Brunei Darussalam, Cambodia, India, Indonesia, Laos, Malay-sia, Myanmar, Philippines, Singapore, Thailand, Timor-Leste, Vietnam. Widely distributed from northeast India and Bangladesh, through most of mainland Southeast Asia to the islands of East Malaysia, Indonesia, Timor-Leste, and the Philippines. Synonymy. – Testudo melanocephala Van-Ernest in Daudin 1801 (nomen oblitum), Emys mela-nocephala, Clemmys (Clemmys) melanocephala, Testudo amboinensis Riche in Daudin 1801, Emys amboinensis, Terrapene amboinensis, Cistuda amboinensis, Cuora amboinensis, Cistudo amboinensis, Cyclemys amboinensis, Emys (Cistuda) amboinensis leveriana Gray 1830.
... The long maritime history and high intensity shipping activities of Singapore would have exposed its marine environments to elevated risks of marine biological invasions. However, while established non-indigenous species have been well documented in Singapore's terrestrial (Corlett, 1988;Turner & Tan, 1992;Ng et al., 1993;Lim & Gardner, 1997;Wee, 1997;Tan & Buck, 2002;Teo et al., 2003;Ng, 2009;Lok et al., 2010aLok et al., , 2010bLok et al., , 2010c and freshwater (Ng & Lim, 2010;Yeo, 2010) environments, the historical records of marine counterparts are inadequate (Chou & Lam, 1989;Puthia et al., 2010). Chou & Lam (1989) listed the euryhaline Mozambique tilapia, Oreochromis mossambicus, as the only marine species that had established feral populations in Singapore in their review of aquatic non-indigenous species. ...
The introduction of marine non-indigenous species is a global concern. Addressing the problem is made more challenging by the defi ciency of data for non-indigenous estuarine and marine organisms, especially within Southeast Asia. In Singapore, three of the most important categories of marine invasion pathways are present: 1) shipping-related pathways, 2) commercial culture and fi sheries, and 3) the ornamental trade. In this study, we conducted an exhaustive review to determine the status of and estuarine non-indigenous species in Singapore. A total of 17 non-indigenous species are established in estuarine and marine environments in Singapore. Commercially important non-indigenous species, which are imported for trade but are not known to be present in the environment, were also reviewed. We concluded by highlighting research directions aimed towards setting up a meaningful management framework for non-indigenous species.
... Cuora amboinensis Daudin, Malayan box terrapin (Fig. 5a) The Malayan box terrapin was recorded twice, in 2009 and 2011, in the secondary forest. The natural origin of this species is doubtful, as terrapins are generally long-lived and often become abandoned pets or are released by the public for gaining spiritual merit (Ng & Lim, 2010). ...
... frequent and sufficiently high number of crabs escaped or released) poses a threat to the surrounding tropical ecosystems and biota. Such as scenario has been observed with other aquatic species imported into Singapore for the live food trade (American bullfrog, Lithobates catesbaeianus) and ornamenal pet trade (red eared terrapin, Trachemys scripta elegans), pest species that are not established, but still present in considerable numbers in the wild because of frequent releases (Yeo and Chia 2010;Ng and Lim 2010). ...
The introduced Chinese mitten crab, Eriocheir sinensis H. Milne Edwards, 1853, considered amongst '100 of the world's most invasive alien species', has been well-documented in Europe and North America. Most recently, it was recorded in subtropical western Asia (northern Iran). Here, we report E. sinensis from Singapore; the first record of this species in the wild from the tropics. While the likelihood of establishment of this temperate species in the tropics is low, potentially high and sustained propagule pressure could still allow it to pose a potential threat to native ecosystems and biota, a scenario with precedence in Singapore. Efforts by regulatory agencies are urgently needed to monitor and prevent the introduction of this potential invasive alien species.
Biological control is the management of non-native species through the use of their natural enemies. The Green Iguana (Iguana iguana), a large lizard of the Neotropics, has established populations in extralimital countries. There has been an increasing recent pattern of reports of free-living Green Iguanas in Hong Kong, which was the trigger of this desktop assessment of native Hong Kong fauna that may prey upon escaped or released iguanas. A literature review found documented predators of Green Iguanas from 12 vertebrate orders. There were two mammalian orders (Carnivora, Primates), eight avian orders (Cuculiformes, Pelecaniformes, Accipitriformes, Cathartiformes, Falconiformes, Strigiformes, Piciformes, Passeriformes), and two reptilian orders (Squamata, Crocodylia), which are all presently represented in Hong Kong with the exception of the orders Cathartiformes and Crocodylia. Based on knowledge of other taxa documented to prey upon lizards represented in Hong Kong, we suggested additional prospective predators of Green Iguanas from one further mammalian order (Artiodactyla) and one further avian order (Ciconiiformes). Since avian species generally have a greater representation in settled areas, along with stray domestic dogs and cats, we expect these species to be the potential predators most likely to take iguanas when they are first released or escaped.
Given Singapore’s location at the confluence of important maritime trading routes, and that it was established as a British East India Company trading post in 1819, it is unsurprising that Singapore has become one of the centres of natural history collecting and research in Southeast Asia. Despite its small size, Singapore is home to a diverse herpetofauna assemblage and boasts a rich herpetological history. The first systematic studies of Singapore’s herpetofauna (within the Linnaean binomial framework) date back to Stamford Raffles and the naturalists hired by him who first came to the island in 1819. Specimens that were collected during and after this time were deposited in museums worldwide. Over time, 39 species from Singapore were described as new to science. Due to the entrepôt nature of Singapore with its associated purchasing and trading of specimens (both alive and dead), poor record-keeping, and human introductions, numerous extraneous species from outside of Singapore were reported to occur on the island. Such issues have left a complicated legacy of ambiguous records and taxonomic complications concerning the identity of Singapore’s species-rich herpetofauna, many of which were only resolved in the past 30–40 years. By compiling a comprehensive collection of records and publications relating to the herpetofauna of Singapore, we construct an updated and more accurate listing of the herpetofauna of Singapore. Our investigation culminated in the evaluation of 309 species, in which we compiled a final species checklist recognising 166 species (149 native and 17 non-native established species). Among the 149 native species are two caecilians, 24 frogs, one crocodilian, 13 turtles (three visitors), 34 lizards, and 75 snakes. Of the 17 non-native species are five frogs, four turtles, six lizards, and two snakes. The remaining 143 species represent species to be excluded from Singapore’s herpetofauna species checklist. For each of the 309 species examined, we provide species accounts and explanatory annotations. Furthermore, we discuss Singapore’s herpetofauna from a historical and conservation perspective. Immediate deforestation and nationwide urbanisation following colonisation completely eliminated many species from throughout much of the country and restricted them to small, degraded forest patches. We hope this publication highlights the importance of publishing observations and serves as a valuable resource to future researchers, naturalists, biological consultants, and policy makers in initiating studies on species ecology, distribution, status, and promoting conservation efforts to safeguard Singapore’s herpetofauna.
Presently, the only established populations of invasive Green Iguanas (Iguana iguana) on the mainland USA occur in Florida. We examined observation data from the online citizen-science application iNaturalist to determine the frequency of reports of free-living Green Iguanas in Florida and identify where iguanas have been reported in other parts of the mainland USA. Observations from Florida comprised 99.6% of the 5,929 verified Green Iguana observations from the mainland USA. The largest proportion were observations from 2016 to 2021, corresponding with an increasing number of application users contributing to the dataset during this period. The majority of Green Iguana observations from latitudes of 27–41°N in 11 other mainland states were from California. However, we noted no obvious concentrations of sightings to indicate the presence of established populations in any of those 11 states. The majority of observations from outside Florida were adults and were most frequently reported from suburbia and urban parks, suggesting that released or escaped pets were the likely source. More than one third of iguanas reported outside Florida were near water, which is worrisome because iguanas are known to use waterways to disperse. This study clearly demonstrates the value of public participation in assembling sighting records of non-native animals, and we encourage engagement campaigns that leverage reports from members of the public to achieve early detections of potentially invasive species.
In 1996, the IUCN-SSC Crocodile Specialist Group assigned the status ‘Regionally Extinct’ to Crocodylus porosus in
Singapore for the International Union for Conservation of Nature Red List.
No study appears for the status review, and Crocodylus porosus is still considered ‘regionally extinct in Singapore’. This paper provides a basis for future amendment, with continuous accounts of both historical and current presence, whilst covering trade, folklore and historical impacts.
An overview of the invasive alien species situation in Singapore is presented. An updated checklist of introduced or alien animals in Singapore is provided; of the 142 species of invertebrates and vertebrates documented, more than 70% are considered established. A brief introduction and discussion of pertinent definitions and terminology for describing invasive alien species, with particular reference to Singapore, is included. In addition, important pathways for biological invasion into Singapore are highlighted, and legislation and institutional roles with respect to alien species issues in Singapore are summarized, featuring examples of management programmes. The article concludes by identifying areas emphasized in recently published alien species research in Singapore and knowledge gaps that need to be filled.
Introduced or alien freshwater decapod crustaceans from Singapore's reservoirs are documented from the results of an ongoing survey. Four species of decapods were recorded in the reservoirs, viz., one freshwater crayfish, Cherax quadricarinatus (Parastacidae) and three freshwater shrimps, Macrobrachium lanchesteri, M. nipponense, and M. aff. inflatum (Palaemonidae). Native decapods were not found in the actual reservoirs, but in forest stream inlets draining into the reservoirs. All four species were introduced through the ornamental pet trade, indicating the significance of this invasion pathway in Singapore. As yet, no ecological impacts on native ecosystems are known for these introduced species, although the possibility that they could be undergoing a lag phase or of more invasive alien decapods being introduced cannot be discounted.
Using mtDNA sequences of historical museum specimens, including the herein designated lectotype of Tetraonyx affinis Cantor 1847 and topotypic specimens of Trionyx (Tetraonyx) cuvieri Gray 1831 and Tetronyx longicollis Lesson 1834, we demonstrate that the name Batagur affinis (Cantor 1847) has to be used for a recently identified critically endangered terrapin species from Southeast Asia. Further, we provide evidence that Batagur baska (Gray 1830) historically was dis-tributed from north-easternmost India and Bangladesh to at least the Ayeyarwady and Bago estuaries in Myanmar while B. affinis occurs in the southern Malay Peninsula and Sumatra. The taxonomic allocation of the extant and extirpated Batagur populations in the northern Malay Peninsula, Cambodia and southern Vietnam remains unclear. A museum specimen from the mid-19 th century suggests that B. baska once also occurred in the Indus Delta of southern Pakistan.
The red-eared slider Trachemys
scripta
elegans is currently the only reptile species that can be legally sold as a pet in Singapore. We report on the species of tortoises and freshwater turtles that were found for sale during a survey of 27 pet shops in 2004. Although the red-eared slider was the most common species for sale, small numbers of 11 other species were available. Of these, the import of one species (the Chinese soft-shell turtle Pelodiscus
sinensis) is allowed for food but import of the other 10 species is not permitted for either food or the pet trade. We found that illegally held chelonians are often not kept on the pet shop premises. Our findings suggest that the Singaporean authorities' efforts to address illegal wildlife trade have to include other methods in addition to conducting raids on shop premises.
This chapter reviews what is currently known about the status of red-eared sliders in Asia, as well as the potential impact
of this non-indigenous species (NIS) on the native Asian biota. It includes published literature, information from websites,
as well as mentioning ongoing research where known.
Singapore's location at the centre of major air and shipping routes has resulted in the introduction of numerous species of freshwater animals from various parts of the world. To date, some 37 introduced freshwater fishes, turtles, molluscs and prawns have become established here. Studies show that the introduced species have not significantly affected the fauna in pristine forested streams. This is probably because much of the native freshwater fauna includes acid-water species, whereas introduced ones prefer more neutral and harder waters. Of the 54 native Singapore freshwater fishes, the greater majority (over 80%) are forest species adapted to living in acid waters. These species have suffered mainly because of forest clearance and more than 50% of this fauna is now extinct. A similar situation occurs for freshwater prawns. The conservation of the native freshwater fauna in Singapore should thus centre on the preservation of their natural forest habitat. There is a potential danger posed by imported fishes which originate from soft, acid waters in Africa, South America or other parts of Southeast Asia. Thus far, only one or two species have managed to establish themselves in Singapore. Legislation and appropriate quarantine measures will be needed to ensure that alien tropical acid water species do not become established here.
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