REPORTS 28 Biomonitoring of Singapore's Freshwater Ecosystems

Biomonitoring of Singapore's Freshwater Ecosystems

Text by Esther Clews, Yijun Lin, and Hans Eikaas Images as credited

Freshwater Biomonitoring “Biological monitoring” or “biomonitor- nutrients and other factors associated with expert interpretation, biotic indices are ing” is the use of animals and plants to the biological health of freshwater systems often developed as compound metrics of detect change, often due to pollution, in were also monitored. The use of biological condition for ease of interpretation and the environment. The monitoring of biologi- indicators in monitoring marks a conceptual communication to stakeholders. cal communities offers a means of holistic transition from single parameter assess- environmental appraisal to detect impair- ments towards an evaluation of ecologically Benthic invertebrates are the most ment, because these integrate the physical relevant change. commonly used communities in the assess- and chemical aspects of their immediate ment of the health of lotic freshwater environment over time. Traditionally, fresh- In the freshwater environment, fish algae and systems worldwide and are being increas- water monitoring programmes undertook benthic invertebrates are effective “bioindi- ingly adopted for standing waters (Rosen- routine or “surveillance” monitoring of key cators” of pollution or disturbance because berg and Resh 1993). Their communities pollutants of concern primarily for drink- they demonstrate differential sensitivities comprise insect larvae, snails, shrimps, ing water quality. Over the last 50 years, to pollution. In the case of freshwater algae, and worms that live predominantly in the monitoring of freshwater quality has some species are of particular concern with the sediments at the bottom of lakes and evolved from simple chemical analysis regard to toxic algal blooms, so they are streams. Some worms and midge larvae of water samples through to the use of a often monitored as a water quality concern are able to tolerate relatively polluted multitude of chemical, physical, and biologi- of their own right as well as indicators of waters, whereas others, such as mayflies cal metrics developed to comprehensively enrichment, particularly in lake systems. and stoneflies, are sensitive to pollution indicate the condition of water bodies. As While the use of particular indicator taxa (Fig. 1). The presence and/or abundance our understanding of these systems devel- may be a valuable aspect of biomonitoring, of these animals may be weighted by their oped along with the problems associated whole community responses offer a more respective sensitivities to pollution so as to with algal blooms caused by excessive plant holistic representation of environmental calculate biotic indices of water quality and nutrients to freshwater systems from either conditions. However, because community ecological health. Because the presence agricultural or domestic sources, these level information is complex and requires of different invertebrates in the sediments CITYGREEN #5 A Centre for Urban Greenery and Ecology Publication 29

Worm

Dragonfly Cased Caddisfly

Stonefly

Swimming Mayfly Wood-boring Mayfly Chironomid Midges

Pollution-sensitive fauna Pollution-tolerant fauna No fauna "Clean water fauna"

Pollution

Good Water Quality Poor Water Quality

Invertebrates as Indicators of Pollution

is indicative of the conditions of the fresh- The adoption of biotic indices devel - water system throughout their aquatic life oped for temperate countries provides spans, the use of these indices of ecologi- a valuable shortcut to establishing cal conditions in a comprehensive monitor- indices, as long as modifications are ing programme effectively complements made to include local taxa. However, this periodic chemical point-sampling, which approach may misinterpret the sensi - may miss sporadic pollution events. tivities of resident invertebrates without local validation of faunal associations While freshwater biomonitoring has a long with environmental parameters. A more history in Europe and North America, it robust but more data-intensive and is only more recently being adopted in costly means of establishing local biotic Southeast Asia. In many Asian countries, in d ice s is to b u il d th e m o n th e a s so ciatio n monitoring of freshwater quality is primar- between local water quality and inverte - ily undertaken via traditional physiochem- brate communities. This not only ensures ical and microbial measurements, with that the indices are locally relevant but biomonitoring routinely applied only in also establishes local capability and Japan, Korea and Singapore (Morse et al. understanding of freshwater systems, 2007). Researchers in Malaysia, Thailand, which are important for the testing of and Vietnam have adapted bioindicators the indices and their operational use of stream water quality from Europe - within the relevant country. In all cases, an indices, such as the UK’s Biological biotic indices and sampling methods 1. Photographs taken in fulfillment of collaborative research projects with NUS, Monitoring Working Party index, but must be standardised, quantitative, and PUB, and University of Canterbury, these have not yet been implemented in repeatable to ensure comparability over New Zealand (Photos: Stephen Moore; monitoring programmes. time and among sampling stations. Diagram by the authors). REPORTS 30 Biomonitoring of Singapore's Freshwater Ecosystems

Development of Survey Protocols & Indices Research & Development

Established Baseline

Operational Monitoring

Assessment & Evaluation of Change

Identification of Evaluation of Pollution Issues Management

Operations & Management Recommendations for Management

Biomonitoring Programmes and Application

In Singapore Singapore-specific biotic indices for reser- canals within residential, commercial, and tics. In running waters, standard methods voir water quality and stream health using industrial areas. These two types of water applied internationally were adopted, benthic macroinvertebrates were devel- bodies not only support different biologi- namely “sweep” and “surber” sampling. The oped in collaboration between local and cal communities due to their very different sweep sampling procedure involves kicking international universities and Public Utilities retentions of water and associated chemi- the stream substrata to disturb and release Board, Singapore (PUB). The Benthic Quality cals but are also ecologically susceptible to invertebrates into a net held downstream.

Index-Singapore (BQISING index) of tropical different types of pollution. In the reservoirs, Sweep samples are collected from a wide reservoir water quality was developed by the input of plant nutrients, such as nitrate range of microhabitats (for example, leaf the National University of Singapore (NUS) and phosphate, are of principal concern packs, cobbles, pools, log jams, and stream (Clews et al. 2009; Loke et al. 2010). Concur- with respect to the growth of potentially margins) over a two-minute period within rently, the University of Canterbury, New toxic algae. Conversely, in the streams, the a ten-metre-stream-reach delimiting each Zealand, developed the SingScore index of constant flushing of water usually mitigates site. Surber sampling works similarly to waterway health in Singapore (Blakely and against the accumulation of planktonic algal sweep sampling except that in this case the Harding 2010). Both indices were created populations but concentrations of heavy hands are used to disturb a fixed area of the using a weighted average approach to metals and other chemicals derived from stream bed to release invertebrates into a determine the sensitivity of the invertebrate urban and industrial runoff have a greater net. Invertebrates collected during an initial families to pollution, based on invertebrate potential to impair their health. Thus, the survey of 47 streams were used to derive

and water quality data collected during an BQISING index of reservoir water quality the SingScore index. intensive field investigation. was therefore designed to assess nutrient enrichment in Singapore’s reservoirs and Methods for the collection of invertebrates Two separate indices were developed, the SingScore index was created to assess from lentic systems, especially hard- one for each of the two primary fresh- urban pollution, based principally on heavy edged ones, are less well established. water habitats in Singapore: first, reser- metal contamination. Artificial substrate samplers, consisting voirs representing standing waters, and of coconut brushes combined with split second, running waters that comprise The methods applied to collect inverte- palm fronds, were identified as the most natural streams within the protected brates from these two habitats also differ, effective method of sampling these tropi- Nature Reserves and concrete drainage again due to their hydrologic characteris- cal urban reservoirs in Singapore (Loke 31

"Biological monitoring" or "biomonitoring" is the use of animals and plants to detect change, often due to pollution, in the environment.

et al. 2010). These samplers were placed and funding from PUB. The EMID group in 15 reservoirs and two quarry lakes and specialises in the ecological monitoring and the communities that colonised them assessment of aquatic systems while the were retrieved after one month in order to Catchment and Waterways department of calculate the BQISING index. PUB is responsible for the management of Singapore’s “raw” waters. Validation of the biotic indices developed is important to ensure that they are consist- Initially the validation phase targeted five ently representative of the water quality and reservoirs and multiple sites on three water- ecological health. Even in fully operational ways. This has now been supplemented with programmes, it is important to continue to use operational data following the expansion of the wealth of data collected as feedback for the programme to include all of Singapore’s our understanding of the system and modify reservoirs and an additional 14 waterways the monitoring protocol if necessary (Fig. 2). from October 2011. The results of the first For example, seasonal and extreme events three years of biomonitoring will be used to may be captured, improving the data cover- identify the appropriate sampling times and age for deriving the underlying models of frequencies required for a country-wide faunal-response to environmental conditions. freshwater biomonitoring programme.

Biotic indices calculated on the communi- Whilst freshwater ecology research in ties retrieved by these methods are now temperate regions is very well established, being tested and validated in under the the effects of the monsoon, extreme events, Long-term Bio-index Project undertaken and climate change on freshwater ecosys- by the Freshwater Section of the Ecologi- tems in the tropics are less well known. This cal Monitoring Informatics and Dynam- work further supports research to better ics (EMID) group at the Tropical Marine understand tropical freshwater systems in Science Institute (TMSI), NUS, with support highly urbanised environments (Fig. 2). 2. (Diagram by the authors). REPORTS 32 Biomonitoring of Singapore's Freshwater Ecosystems

Applications In Singapore, the operational use of th e se initiative s c a n g a u g e th e ir ef fe c tive n e s s The authors would like to thank PUB for biotic indices in a national biomonitoring and inform future enterprises. The progress its collaboration and funding of freshwater programme to detect pollution began in of efforts to restore the health of waterbod- biomonitoring in Singapore—Mr. Harry Seah, Dr. October 2011. This programme now serves ies can be tracked against reference sites E-wen Low, and Mr. Matej Faller in particular for as additional surveillance monitoring to where no management has been undertak- their work to realise the value of this research complement the water quality and algal en. For example, shifts in the composition of and facilitate operations. This work would not be sampling which are routinely conducted by the macroinvertebrate community, from one possible without the support of National Parks PUB. Tracking changes in environmental dominated by pollution-tolerant taxa to one Board, which permitted the collection of inver- and water quality is especially important in with a greater variety of organisms sensi- tebrates as well as provided constructive advice water bodies used for recreation, for drink- tive to perturbations at the managed site, in and information on the locations monitored. We ing water or as reserves to conserve local the absence of change at the reference site, would also like to thank our colleagues within biodiversity, more so if they are likely to be would indicate improved ecological quality. the EMID group at TMSI for their tireless opera- impacted by surrounding anthropogenic tional work and assistance with the develop- activities, such as deforestation, industry, One example of the application of biomoni- ment of material presented in this article. Many urban development, and agriculture. A toring in Singapore is the appraisal of the thanks to Prof. Peter Ng for his endorsement of decline in the animals known to be sensitive Kallang River @ Bishan-Ang Mo Kio Park this programme and its development at NUS. to a specific pollutant combined with water ABC Waters project. A three-kilometre analysis can provide clear evidence of how a stretch of Kallang River that flows through particular activity may be adversely affect- Bishan Park was restored from a concrete ing the water quality. Such information canal into a naturalised meandering river can then contribute towards management that flows through the park, adding aesthetic decisions for the development of pollution value as well as providing a greater capacity control measures and best management for stormwater treatment and drainage (Fig. practices, and also provide a means to 3). With the return of vegetated banks and test the effectiveness of these strategies in varied in-stream habitats, the restoration mitigating and minimising pollution. of the Kallang River should create habitats for aquatic life, increase the aquatic biodi- Biomonitoring is also used in Singapore and versity, and improve ecological functioning elsewhere as a component of investigative (such as nutrient uptake and cycling) within monitoring to further identify the causes the former concrete canal. of pollution and in environmental impact assessment (Metcalfe-Smith 1996). Environ- Before construction works began, biomoni- mental impact assessment often refers to an toring commenced in the Kallang River to evaluation of potentially adverse impacts on serve as a baseline of the local macroin- the environment, such as a new construc- vertebrate community, habitat, and water tion or development. While biomonitoring quality. Ecological changes are currently can be and is used as a means of assess- being tracked in the park as well as at two ing changes following activities that may reference locations: one urban drain and one disturb ecosystems, it is also used to evalu- natural stream. This will allow for the robust, ate management strategies designed to scientific evaluation of the effectiveness of improve water quality or ecosystem health. the ABC Waters Programme in meeting its targeted objectives. If effective, we would In Singapore, the Active, Beautiful and expect to see a departure from the condi- Clean (ABC) Waters Programme aims to tions in the urban drain and a move towards improve flood control and water quality and the more natural, healthy stream. to enhance biodiversity through in-stream, riparian, and wetland design features within Routine assessment through biomonitor- the predominantly urban landscape of ing in combination with dedicated evalu - Singapore (PUB 2011). Further, to the specif- ation of rehabilitation projects continues ic objectives of the ABC Waters Programme, to improve our understanding of local Singapore’s pioneering role in the interna- freshwater ecosystems (Fig. 2). This will tional Cities Biodiversity Index (CBI) also further elucidate system requirements requires that we support our local biodiver- for effective habitat creation and rehabil - 3. The Kallang River @ Ang Mo Kio-Bishan Park, Singapore, following sity by providing for and conserving habitats itation to meet management goals, such rehabilitation under the Active, Beautiful within the urban jungle (CBD 2009). The as reduced pollutant loads and enhanced and Clean Waters Programme biomonitoring and ecological appraisal of biodiversity in Singapore. (Photo: Adam Quek). 33

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