Contributions to Marine Science 2012 Contributions to Marine Science 2012: 121–126 Date of Publication: 29 Sep.2012 © National University of Singapore
OBSERVATIONS ON THE SUBTIDAL FOULING COMMUNITY ON JETTY PILINGS IN THE SOUTHERN ISLANDS OF SINGAPORE Ong Jia Lin, Joyce Tropical Marine Science Institute, National University of Singapore, 18 Kent Ridge Road, Singapore 119227. Email:
[email protected]
Tan Koh Siang Tropical Marine Science Institute, National University of Singapore, 18 Kent Ridge Road, Singapore 119227. Email:
[email protected]
ABSTRACT. — Most published research in marine biofouling communities has focused on ships and other floating structures such as settlement plates. More recently, with the increased concern in surveillance for invasive species in Australia, studies on static artificial structures such as jetty pilings have been surveyed for the fouling assemblages present. In this study, we report the biodiversity of fouling communities found on jetty pilings in six sites across the southern islands of Singapore. Results suggest that even within small spatial scales, there are differences in the assemblages of biofouling organisms amongst some sites. Raffles Lighthouse and Pulau Hantu had assemblages with higher diversity of hard corals and the absence of bryozoans and sea fans. Kusu Island, Sisters Laut and St Johns’ Island had very similar assemblages with higher algal diversity and less species of hard corals. These differences appear to be influenced by geographical distance, variable water quality and depth of pilings. KEY WORDS. — Biofouling, jetty pilings, assemblages, spatial variation, depth
INTRODUCTION
developmental process (Lin & Shao, 2002), effects of sunlight and shade (Nandakumar, 1995), orientation of plates (Somsueb et al., 2000), effects of environmental stress (Turner et al., 1997), effects of marinas on composition of fouling assemblages (Web & Keough, 2000) and seasonal variability (Satheesh & Godwin Wesley, 2008). In an experiment comparing communities on floating and fixed settlement plates (Perkol-Finkel et al., 2006), the proportions of taxonomic groups within the communities were different due to varying hydrodynamic characteristics of floating versus fixed habitats. This might be an indication of the need to focus research on the actual artificial substrates themselves rather than extrapolating results from floating substrates put into the water to fixed artificial substrates. As was concluded by Berntsson & Jonsson (2003), there is a risk of extrapolating results performed using static panels to fouling conditions on boat hulls because of the different flow regimes affecting preferential settlement.
The issue of biofouling has plagued humanity since artificial structures such as boats, jetties, harbors, oil platforms and wind turbines were built and used in the sea. Some of the impacts of biofouling include ships (by significantly increasing drag), mariculture (reduction of water flow around nets and cages), ocean pipelines and underwater instruments. Across the world, substantial research has been conducted on this topic, ranging from observing the assemblages on artificial substrates (their successional, spatial and temporal patterns) to methods for how to get rid of or reduce the amount of fouling organisms on artificial structures (e.g. Butler, 1986; Lin & Shao, 2002; Underwood & Chapman, 2006; Perkol-Finkel et al., 2008; Andersson et al., 2009). It has become increasingly obvious that assemblages that grow on artificial substrates are different from those that grow on natural substrates (Connell & Glasby, 1999; Glasby, 1999; Stachowitsch et al., 2002; Bacchiocchi & Airoldi, 2003) and may influence the ecology of surrounding natural habitats.
Much research has been conducted on jetty pilings in Australia (such as Kay & Keough, 1981; Kay & Butler, 1983; Butler, 1986; Glasby, 1999; Moreau et al., 2008), in America (example Lenihan et al., 1990; Atilla et al., 2003) and even Europe (Andersson et al., 2009). In Asia, research
Many experiments have been carried out on settlement plates deployed in the field, some examples being community
121
Fouling communities on jetty pilings Table 1. Dates of surveys conducted and site characteristics. Depth refers to the average depth of pilings at high tide in metres. Date
Site
Piling Material
Year Built
Depth (m) of piling
8 Jan.2010
Sisters Laut
Steel
1999
7.0
8 Jan.2010
Kusu
Steel
1999
7.7
18 Mar.2010
St Johns’
Steel
1992
9.0
29 Mar.2010
Raffles
Steel
Unknown
4.0
30 Mar.2010
Tekukor
Concrete
1980s
4.0
30 Mar.2010
Hantu Besar
Concrete
1980s
2.5
on biofouling has mainly been focused on settlement plates (Japan – Nandakumar, 1995; Taiwan – Lin & Shao, 2002; Hong Kong – Dobretsov et al., 2005; India – Satheesh & Godwin Wesley, 2008) as well as other artificial floating structures for example petri dishes suspended from a floating pontoon in Hong Kong (Dobretsov et al., 2010) and net panels in Malaysia (Madin et al., 2009). Intertidal biofouling communities have been studied on pier pilings in Mirs Bay, Hong Kong by Huang et al. (1992) in which species differences in quantities and vertical distribution were recorded on the five piers.
dates of the surveys. During underwater surveys, photographs of the fouling community were taken over a range of depths along the length of the piling, starting from 0.5m below Mean Low Water Springs (MLWS) to target only subtidal organisms. At least two pilings were photographed per site. Voucher specimens were brought back to the laboratory for identification. In addition to the identification of collected specimens, organisms from the fouling community in the photographs were identified to the highest taxonomic category possible. Presence/absence data was generated from this list of species for all sites.
The aim of this preliminary study was to survey subtidal biofouling organisms found on jetty pilings in Singapore and to see if there were any differences across the six sites within the southern islands. Fouling on fixed artificial structures has not been surveyed before in Singapore and this research is the first to be carried out on relatively ‘mature’ jetty pilings (more than 10 years old) in the southern islands of Singapore.
The statistical package Primer (version 6) was used to perform statistical analyses and the main analyses run were Bray-curtis similarity matrices, cluster analyses, MDS (multidimensional scaling) and SIMPER (similarity percentages). MDS plots were used because of the number of variables (27 variables – different organisms found). MDS can take into consideration the presence or absence of all 27 variables, therefore looking at the fouling community as a whole rather than as separate species, genus or higher order taxonomic groups.
MATERIAL AND METHODS RESULTS
Subtidal fouling communities were surveyed on jetty pilings by SCUBA dive between January and March 2010. Six sites located in the southern islands of Singapore were selected: St Johns’ Island, Sisters Island (Laut), Kusu Island, Pulau [=island] Tekukor, Pulau Hantu Hantu (Besar) and Raffles Lighthouse (see Figure 1 for map). Descriptions of the jetty pilings at the various sites are listed in Table 1, along with
The list of 27 variables (organisms identified to highest taxonomic category possible) used for all statistical analyses are shown in Table 2, along with presence/absence data at the six sites. Common organisms encountered at most sites included Bryopsis sp., Asparagopsis taxiformis, encrusting sponges, Carijoa riisei, Tubastrea sp., and hydroids. Kusu Island, Sisters Laut and St Johns’ Island had higher diversity of algae compared to the other sites. Raffles Lighthouse, Pulau Hantu and Pulau Tekukor had higher diversity of scleractinian corals. Zoanthids were only observed at Pulau Tekukor and the hydrozoan Distichopora violacea only seen at Raffles Lighthouse. At all pilings, algae dominated the top zone (along with soft corals if present except for Carijoa riisei which was not observed at the top zone), followed by encrusting sponges in the middle zone and hydroids occurring primarily at the deepest zone of the pilings (see Figure 2 for illustration). Cluster analysis of all sites were performed (Figure 3) and the results show that two main locational clusters were formed, one cluster being Pulau Hantu and Raffles Lighthouse, and the other cluster consisting of Pulau Tekukor, Sisters Laut, Kusu
Fig. 1. Location of jetties sampled between January and March 2010. Adapted from Lee KK and Goh SN from Hydrographic Department, Maritime Port Authority of Singapore. Positions in WGS 84.
122
Contributions to Marine Science 2012 Table 2. List of various species, genera or higher taxonomic groups used in the analyses, along with presence/absence data at all six sites. RLH= Raffles Lighthouse; HTB= Pulau Hantu Besar; TEK= Pulau Tekukor; KUS= Kusu Island; SIL= Sisters Laut; and SJI= St. Johns’ Island+. Organisms/Site Amphiroa/Jania sp. Asparagopsis taxiformis Bryopsis sp. Caulerpa sp. Halymenia sp. Padina sp. Sargassum sp. Turfing algae Encrusting sponges Unknown hydroid Distichopora violacea Zoanthus sp. Palythoa sp. Family Melithaeidae Carijoa riisei Dendronephthya sp. Nepthea sp. Tubastrea sp. Family Caryophyllidae Montipora sp. Goniastrea sp. Cyphastrea sp. Pocillopora sp. Trachyphyllia sp. Reteporella sp. Colonial ascidian Solitary ascidian
KUS
SIL
SJI
RLH
TEK
HTB
+ + + + +
+
+ + +
+
+ + + +
+ + + + +
+
+ + +
+ + + + +
+ + + +
+
+ + + +
+ + + + +
+ + +
+ + +
+ +
+
+ +
+ + +
+
+ + + +
+ + +
+ + + +
+ + + +
+ + + +
+ + +
+
Island and St. Johns’ Island. MDS results (Figure 4) also show the same two clusters. Within the Pulau Tekukor, Sisters Laut, Kusu Island and St. Johns’ Island cluster, the MDS shows that
+
+ + + +
+ +
the assemblage found at Pulau Tekukor is slightly different from the other three sites that are very similar to each other (all overlapping on the MDS). SIMPER analyses revealed that
Fig. 2. Jetty piling profile of the six sites grouped by average depth of pilings, showing general zonation of common organisms found.
123
Fouling communities on jetty pilings biofouling assemblages on pier pilings (Kay & Keough, 1981; Kay & Butler, 1983; Glasby, 1999) have reported serpulids, spirorbids, ascidians, algae, sponges and bryozoans as the dominant organisms. Results from this preliminary study show some similarities (presence of algae, sponges and ascidians) as well as some differences (lack of dominance of serpulids, spirorbids and bryozoans). This does not imply the absence of serpulids, spirorbids and bryozoans in Singapore waters, because these organisms have been observed on navigational buoys, floating fish and mussel farms (personal observations). Rather, this seems to support the view that fixed and floating substrates have different assemblages (Berntsson & Jonsson, 2003; Perkol-Finkel et al., 2006, 2008).
Pulau Tekukor was different from Sisters Laut, Kusu Island and St. Johns’ Island because of the presence of hard corals (Goniastrea sp. and Trachyphyllia sp.) as well as zoanthids (Zoanthus sp. and Palythoa sp.). The separation of the two groups as shown in both the cluster analysis and MDS was attributed to lower algal diversity (Asparagopsis taxiformis, Halymenia sp. and Caulerpa sp. absent), dominance in hard corals (presence of Pocillopora sp. and Cyphastrea sp.), and the absence of bryzoans, seafans and soft corals in the Pulau Hantu and Raffles Lighthouse cluster. DISCUSSION
Both cluster and MDS analyses (Figures 3 and 4) show that two separate groups based on similarity are formed, one being Pulau Hantu and Raffles Lighthouse, and the other consisting of Pulau Tekukor, Sisters Laut, Kusu Island and St. Johns’ Island. In terms of geographic distance, this grouping is logical since Pulau Tekukor, Sisters Laut, Kusu Island and St. Johns’ Island are close to each other as seen on the map (Figure 1), while Pulau Hantu is separated by a large channel (Jong Fairway) and Raffles Lighthouse is further south, at the southern limits of Singapore waters. Therefore geographic distance seems to contribute to the type of assemblages found on jetty pilings in Singapore. SIMPER also revealed that the differences in assemblages found between the two clusters were that Pulau Hantu and Raffles Lighthouse had lower algal diversity, more species of scleratinian corals and the absence of bryozoans, sea fans and some soft corals. This could be due to differences in water quality (affecting sedimentation and light), differences in larval supply and recruitment and differences in depth of the pilings (Pulau Hantu and Raffles Lighthouse having shallower average depths than the other cluster).
Much of the fouling studies conducted to date have reported barnacles, serpulid worms, hydroids, algae, mussels, ascidians and sponges (some examples are Butler, 1986; Bacchiocchi & Airoldi, 2003; Berntsson & Jonsson, 2003; Andersson et al., 2009). This however includes the intertidal zone that is dominated by barnacles and mussels. Papers on subtidal
Over the past five decades, the Singapore Straits was subjected to increased amounts of effluents from industrial and domestic sources, and sedimentation from erosion and land reclamation because of rapid economic growth (Gin et al., 2001). In particular, high rates of sedimentation due to land reclamation have impacted marine organisms especially coral reefs (Huang et al., 2009). The amount of suspended sediments in the water column is important as it increases the attenuation of light hence reducing the amount of light available for marine organisms (Gin et al., 2003). Dobretsov et al. (2010) showed that solar ultraviolet radiation (UVR) and photosynthetically active radiation (PAR) have a significant effect on the development of tropical biofouling communities. Sedimentation rates are known to be highest near mainland Singapore (Low & Chou, 1994), and this variation in sedimentation and light availability could account for the difference in assemblages (particularly corals) between the two clusters, given that Pulau Hantu and Raffles Lighthouse (15km from coastline) are further away from mainland than the other four sites are (10 km from coastline).
Fig. 3. Cluster analysis of all sites based on Bray Curtis similarity matrices. RLH= Raffles Lighthouse; HTB= Pulau Hantu Besar; TEK= Pulau Tekukor; KUS= Kusu Island; SIL= Sisters Laut; and SJI= St. Johns’ Island.
Fig. 4. Multi-dimensional scaling of all sites based on Bray Curtis similarity matrices. RLH= Raffles Lighthouse; HTB= Pulau Hantu Besar; TEK= Pulau Tekukor; KUS= Kusu Island; SIL= Sisters Laut; and SJI= St. Johns’ Island. Green similarity circle is drawn based on the cluster analysis results.
Results show that 5 taxa of scleractinian corals (excluding cave corals and lace corals) were found on jetty pilings, and the four less common taxa were only found at Raffles
124
Contributions to Marine Science 2012 ACKNOWLEDGEMENTS
Lighthouse, Pulau Hantu and Pulau Tekukor (Table 2). Huang et al. (2009) found that Raffles Lighthouse had the highest coral species richness across eight sites in the southern islands of Singapore, and this large patch of coral reef might be an influential factor in regards to larval supply of corals to the jetty pilings at Raffles Lighthouse and possibly Pulau Hantu. In addition, corals in Singapore do not survive well at deeper depths (Huang et al., 2009) and given that the jetty pilings at Raffles Lighthouse and Pulau Hantu are shallower than the other sites, corals on the seabed next to the jetty pilings at Raffles Lighthouse and Pulau Hantu would help boost the abundance of corals on the pilings, as opposed to the other sites where the presence of corals on the seabed at those depths is highly unlikely.
We thank National Parks Board (NParks) for their financial support in this project (Research grant number R347-000121-490). W are grateful to Maritime Port Authority of Singapore (MPA) and Sentosa Development Corporation (SDC) for permission to undertake the field sampling. Thanks to Yeo Wei for helping out in the field sampling and the rest of the office mates Serina Lee, Chan Jia Hui and Lim Chin Sing for lighting up life in the office. We are grateful for the encouragement and support from colleagues at Tropical Marine Science Institute (TMSI), in particular Dr Sin Tsai Min and Michelle Lee, for their invaluable advice. LITERATURE CITED
Another consideration is the varying amount of light at different depths of the pilings. Studies have shown that shade (less light) affects how assemblages are structured, growth and survival of some marine organisms (example algae, bryozoans and sponges) and even the competitive ability of sessile organisms (Nandakumar, 1995; Glasby, 1999; Blockley, 2007). For example, Glasby (1999) found that the cover of bryozoans was significantly greater on shaded pilings compared to unshaded pilings and this could explain the absence of bryozoans at Raffles Lighthouse and Pulau Hantu because the pilings are shallower hence receive more light than the pilings at Sisters Laut, Kusu Island and St. Johns’ Island. When looking at the cluster consisting of Pulau Tekukor, Sisters Laut, Kusu Island and St. John’s Island, the assemblage found at Pulau Tekukor is different compared to the other three sites (Figure 4). As seen from Table 2, this is because of the absence of some algae (Caulerpa sp. and Halymenia sp.), presence of zoanthids and presence of 2 scleractinian corals on the pilings at Pulau Tekukor. Two possible reasons are attributable to this difference, the material of the pilings or the depth of the pilings. Pulau Tekukor has concrete pilings whereas the other three sites have steel pilings. Andersson et al. (2009) reported different dominant organisms on both steel and concrete pilings but showed that after four months, the assemblages were similar. Given that the pilings have been in the water for more than 10 years and that the assemblage at Pulau Hantu (also with concrete pilings) was not very similar to that of Pulau Tekukor, this explanation does not seem justified. Hence depth of the pilings seems to be an important factor in composition of assemblages, as seen in Table 1 where Pulau Tekukor has shallower pilings compared to Sisters Laut, Kusu Island and St. John’s Island. The observation that depth is important has also been reported directly by Whomersley & Picken (2003) who found apparent depth zones throughout the study, and indirectly in shading experiments where shade (and hence less light) was an important factor in structuring assemblages. If shading resulted in different assemblages, then one would expect that different depths (deeper depths having less light) would also result in different assemblages. Indeed, zonation of dominant organisms was observed in this preliminary study (Figure 2), which warrants further investigation into depth and its effects on the assemblage composition of fouling organisms on pilings.
Andersson, M. H., M. Berggren, D. Wilhelmsson, & M. C. Öhman, 2009. Epibenthic colonization of concrete and steel pilings in a cold-temperate embayment: a field experiment. Helgoland Marine Research, 63: 249–260. Atilla, N., M. A. Wetzel, & J. W. Fleeger, 2003. Abundance and colonization potential of artificial hard substrate-associated meiofauna. Journal of Experimental Marine Biology and Ecology, 287: 273–287. Bacchiocchi, F. & L. Airoldi, 2003. Distribution and dynamics of epibiota on hard structures for coastal protection. Estuarine, Coastal and Shelf Science, 56: 1157–1166. Berntsson, K. & P. Jonsson, 2003. Temporal and Spatial Patterns in Recruitment and Succession of a Temperate Marine Fouling Assemblage: a Comparison of Static Panels and Boat Hulls during the Boating Season. Biofouling, 19: 187–195. Blockley, D. J., 2007. Effect of wharves on intertidal assemblages on seawalls in Sydney Harbour, Australia. Marine environmental research, 63: 409–427. Butler, A. J., 1986. Recruitment of sessile invertebrates at five sites in Gulf St. Vincent, South Australia. Journal of Experimental Marine Biology and Ecology, 97: 13–36. Connell, S. D. & T. M. Glasby, 1999. Do urban structures influence local abundance and diversity of subtidal epibiota? A case study from Sydney Harbour, Australia. Marine Environmental Research, 47: 373–387. Dobretsov, S. V., L. Gosselin & P. Qian, 2010. Effects of solar PAR and UV radiation on tropical biofouling communities. Marine Ecology Progress Series, 402: 31–43. Dobretsov, S. V., P. Qian & M. Wahl, 2005. Effect of solar ultraviolet radiation on the formation of shallow, early successional biofouling communities in Hong Kong. Marine Ecology Progress Series, 290: 55–65. Gin, K. Y. H., S. T. Koh & I. -I. Lin, 2003. Spectral irradiance profiles of suspecded marine clay for the estimation of suspended sediment concentration in tropical waters. International Journal of Remote Sensing, 24: 3235–3245. Gin, K. Y. H., Q. Y. Zhang, E. S. Chan & L. M. Chou, 2001. Threedimensional ecological-eutrophication model for Singapore. Journal of Environmental Engineering, 127: 928–937. Glasby, T. M., 1999. Effects of shading on subtidal epibiotic assemblages. Journal of Experimental Marine Biology and Ecology, 234: 275–290.
125
Fouling communities on jetty pilings Huang, Z. G., S. K. Yan, S. Lin & D. Q. Zheng, 1992. Biofouling communities on pier pilings in Mirs Bay. In Morton, B. (ed.), The Marine Flora and Fauna of Hong Kong and Southern China III. Proceedings of the Fourth International Marine Biological Workshop: The Marine Flora and Fauna of Hong Kong and Southern China, Hong Kong 1989. Hong Kong University Press, Hong Kong. Pp 529–543.
Perkol-Finkel, S, G. Zilman, I. Sella, T. Miloh & Y. Benayahu, 2006. Floating and fixed artificial habitats: effects of substratum motion on benthic communities in a coral reef environment. Marine Ecology Progress Series, 317: 9–20. Perkol–Finkel, S., G. Zilman, I. Sella, T. Miloh & Y. Benayahu, 2008. Floating and fixed artificial habitats: Spatial and temporal patterns of benthic communities in a coral reef environment. Estuarine, Coastal and Shelf Science, 77: 491–500.
Huang, D., K. P. P. Tun, L. M. Chou & P. A. Todd, 2009. An inventory of zooxanthellate scleractinian corals in Singapore, including 33 new records. Raffles Bulletin of Zoology, 22: 69–80.
Satheesh, S. & S. Godwin Wesley, 2008. Seasonal variability in the recruitment of macrofouling community in Kudankulam waters, east coast of India. Estuarine, Coastal and Shelf Science, 79: 518–524.
Kay, A. M. & M. J. Keough, 1981. Occupation of Patches in the Epifaunal Communities on Pier Pilings and the Bivalve Pinna bicolor at Edithburgh, South Australia. Oecologia, 48: 123–130.
Somsueb, S., M. Ohno & D. B. Largo, 2000. Colonization of Fouling Invertebrate Community on Suspended Man-made Structures of Varying Slope Angles. Bulletin of Marine Sciences and Fisheries, Kochi University, 20: 45–50.
Kay, A. M. & A. J. Butler, 1983. ‘Stability’ of the fouling communities on the pilings of two piers in South Australia. Oecologia, 56: 70–78.
Stachowitsch, M., R. Kikinger, J. Herler, P. Zolda, & E. Geutebrück, 2002. Offshore oil platforms and fouling communities in the southern Arabian Gulf (Abu Dhabi). Marine Pollution Bulletin, 44: 853–860.
Lenihan, H. S., J. S. Oliver & M. A. Stephenson, 1990. Changes in hard bottom communities related to boat mooring and tributyltin in San Diego Bay a natural experiment. Marine Ecology Progress Series, 60: 147–159.
Turner, S. J., S. F. Thrush, V. J. Cummings, J. E. Hewitt, M. R. Wilkinson, R. B. Williamson & D. J. Lee, 1997. Changes in epifaunal assemblages in response to marina operations and boating activities. Marine Environmental Research, 43: 181–199.
Lin, H.-J. & K.-T. Shao, 2002. The Development of Subtidal Fouling Assemblages on Artificial Structures in Keelung Harbor, Northern Taiwan. Zoological Studies, 41: 170–182. Low, J. K. Y. & L. M. Chou, 1994. Sedimentation rates in Singapore waters. In: Sudara, S., C. R. Wilkinson & L. M. Chou (eds.), Proceedings of the Third ASEAN-Australia Symposium on Living Coastal Resources. Volume 2: Research Papers. Australian Institute of Marine Science, Townsville. Pp. 697–701.
Underwood, A. J. & M. G. Chapman, 2006. Early development of subtidal macrofaunal assemblages: relationships to period and timing of colonization. Journal of Experimental Marine Biology and Ecology, 330: 221–233. Webb, J. A. & M. J. Keough, 2000. Effects of two marinas on the composition of fouling assemblages. Biofouling, 16: 345–360.
Madin, J., V. C. Chong & B. Basri, 2009. Development and shortterm dynamics of macrofouling assemblages on fish-cage nettings in a tropical estuary. Estuarine, Coastal and Shelf Science, 83: 19–29.
Whomersley, P. & G. B. Picken, 2003. Long-term dynamics of fouling communities found on offshore installations in the North Sea. Journal of the Marine Biological Association of the UK, 83: 897–901.
Moreau, S., C. Peron, K. A. Pitt, R. M. Connolly, S. Y. Lee & T. Meziane, 2008. Opportunistic predation by small fishes on epibiota of jetty pilings in urban waterways. Journal of Fish Biology, 72: 205–217. Nandakumar, K., 1995. Competitive interactions among sessile organisms in Tomioka Bay, south Japan: importance of light conditions on the panel surface. Marine Biology, 121: 713–719.
126
