much higher than recorded in Victoria's other provincial ports: Geelong (17+2), Portland. (7+1) and ...... Portarlington (23 cm diam., August 1996). During April ...
Marine and Freshwater Resources Institute Report No. 25
Exotic Marine Pests in the Port of Melbourne, Victoria.
Brian F. Cohen, Matthew A. McArthur and Gregory D. Parry
February 2001
Marine and Freshwater Resources Institute PO Box 114 Queenscliff 3225
SUMMARY The Port of Melbourne was surveyed for exotic marine species between 4th of August, 1999 and 18th of May, 2000. The survey focused on habitats near commercial wharves, but shipping channels and spoil grounds were also sampled as regions disturbed by port activities are likely to be colonised by exotic species. A variety of techniques were used to detect exotic species. The survey followed nationally accredited guidelines (Hewitt and Martin, 1996) and potential ‘pest’ species identified by the Australian Ballast Water Management Advisory Council (ABWMAC) were targeted particularly. A total of 316 species (excluding phytoplankton species) were collected during the survey, 29 of these species are confirmed as exotic and eight are cryptogenic 1. The following exotic species were found: the dinoflagellates Alexandrium catenella and A. tamarense and the algae Ulva lactuca and Undaria pinnatifida; the northern Pacific seastar Asterias amurensis; the cosmopolitan bryozoans Bugula flabellata, B. neritina and Watersipora subtorquata; the bivalves Corbula gibba, Musculista senhousia, Raeta pulchella and Theora lubrica; the polychaetes Boccardia proboscidea, Euchone limnicola, Neanthes succinea and Sabella spallanzanii; the cosmopolitan isopod Cirolana harfordi; the amphipods Corophium acherusicum and C. insidiosum; the European shore crab Carcinus maenas; the ascidians Ascidiella aspersa, Botrylloides leachii, Botryllus schlosseri, Ciona intestinalis, Styela clava and S. plicata; and, the gobies Acanthogobius flavimanus, Acentrogobius pflaumi and Tridentiger trigonocephalus. The cryptogenic polychaetes Ficopomatus enigmaticus and Myxicola infundibulum; the barnacle Elminius modestus; the amphipods Caprella penantis, C. scaurca and Hamiaegina minuta; and, the isopods Iais californica and Sphaeroma quoianum were also collected. Eight of the 11 ABWMAC target species, Alexandrium catenella, Alexandrium tamarense, Asterias amurensis, Carcinus maenas, Corbula gibba, Musculista senhousia, Sabella spallanzanii and Undaria pinnatifida, were recorded during this survey. One of the three ABWMAC target species not recorded during this survey Alexandrium minutum has been recorded in Port Phillip Bay previously, while the remaining two species Crassostrea gigas and Gymnodinium catenatum do not appear to have established populations in Port Phillip Bay. The recent introductions of Asterias amurensis and Undaria pinnatifida are of concern as their establishment in a busy port has increased their risk of translocation to other temperate Australian ports. This report completes surveys for exotic species in all four commercial ports in Victoria. The number of exotic species detected in the Port of Melbourne (29 exotic + 8 cryptogenic) is much higher than recorded in Victoria’s other provincial ports: Geelong (17+2), Portland (7+1) and Hastings (7). The high diversity of exotic species recorded in the Port of Melbourne is probably due to its long history and the high number of visits by domestic and international ships, its estuarine environment, its location within the large ‘port-like’ environment of Port Phillip Bay, and its proximity to the Port of Geelong.
1
cryptogenic species are those species where it is uncertain whether their distribution is the result of human translocation or natural processes
Exotic Species in Port of Melbourne
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CONTENTS 1 INTRODUCTION......................................................................................................4 2 DESCRIPTION OF THE PORT OF MELBOURNE..............................................4 2.1 PORT DEVELOPMENT ..................................................................................................6 2.2 SHIPPING MOVEMENTS AND VESSEL BALLASTING PATTERNS ......................................7 2.3 PILE CONSTRUCTION AND CLEANING...........................................................................7 2.4 CHANNEL DREDGING AND DREDGE SPOIL REMOVAL.....................................................8 3 EXISTING BIOLOGICAL INFORMATION .........................................................8 3.1 PHYTOPLANKTON ......................................................................................................9 3.2 BENTHIC FLORA .........................................................................................................9 3.3 BENTHIC FAUNA ......................................................................................................10 3.4 DEMERSAL FISH .......................................................................................................10 4 SURVEY METHODS ..............................................................................................11 4.1 PHYTOPLANKTON ....................................................................................................11 4.2 TRAPPING.................................................................................................................12 4.3 DIVER OBSERVATIONS AND COLLECTIONS ON WHARF PILES .......................................12 4.4 VISUAL SEARCHES ....................................................................................................13 4.5 BENTHIC INFAUNA ...................................................................................................13 4.6 EPIBENTHOS .............................................................................................................13 4.7 SEINE NETTING .........................................................................................................13 5 SURVEY RESULTS.................................................................................................14 5.1 EXOTIC SPECIES IN PORT ...........................................................................................14 5.11 ABWMAC target introduced species .................................................................15 5.12 Other exotic species...........................................................................................23 5.2 ADEQUACY OF SURVEY INTENSITY ............................................................................50 5.3 QUALITY CONTROL OF TAXONOMIC IDENTIFICATIONS...............................................51 6 IMPACT OF EXOTIC SPECIES ............................................................................52 7 ORIGIN AND POSSIBLE VECTORS FOR THE INTRODUCTION OF EXOTIC SPECIES FOUND IN THE PORT.............................................................................53 8 DISTRIBUTION OF EXOTIC SPECIES ACROSS VICTORIA’S FOUR COMMERCIAL DOCKS ..........................................................................................54 ACKNOWLEDGEMENTS ........................................................................................56 REFERENCES ............................................................................................................56
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LIST OF TABLES TABLE 1 SUMMARY OF WHARF DEVELOPMENT TABLE 2A SUMMARY OF SAMPLING METHODS, HABITATS AND TARGETED TAXA TABLE 2 B NUMBER OF SAMPLES AND DATE OF SAMPLING FOR EACH SITE AND METHOD TABLE 3 PREVIOUS RECORDS OF ALEXANDRIUM AND GYMNODINIUM IN PORT PHILLIP BAY TABLE 4 EXOTIC SPECIES FOUND AT COMMERICAL WHARVES TABLE 5 PHYTOPLANKTON SPECIES RECORDED TABLE 6 DINOFLAGELLATE CYSTS IN SEDIMENT CORES TABLE 7. SEDIMENT CHARACTERISTICS OF GRAB SAMPLES TABLE 8. MOST ABUNDANT SPECIES IN 1975 AND 1999 GRABS TABLE 9. EXOTIC SPECIES KNOWN FROM FOUR COMMERCIAL PORTS IN VICTORIA TABLE 10. ORIGINS AND VECTORS OF INTRODUCTIONS INTO THE PORT OF MELBOURNE
LIST OF FIGURES FIGURE 1 MAP OF THE PORT OF MELBOURNE FIGURE 2 MAP OF VICTORIA DOCK FIGURE 3 MAP OF APPLETON DOCK FIGURE 4 MAP OF SWANSON DOCK FIGURE 5 MAP OF MARIBYRNONG NO. 1 BERTH FIGURE 6 MAP OF HOLDEN OIL DOCK FIGURE 7 MAP OF WEBB DOCK FIGURE 8 MAP OF GELLIBRAND AND BREAKWATER PIERS FIGURE 9 MAP OF PRINCESS AND STATION PIERS FIGURE 10 LOCATION OF SMITH- MCINTYRE GRAB SAMPLES FIGURE 11 LOCATION OF SLED TOWS AND BEACH SEINE NETS FIGURE 12 CUMULATIVE SPECIES CURVES
Exotic Species in Port of Melbourne
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1.0 INTRODUCTION The establishment of exotic organisms in foreign ports is not a new phenomenon. Exotic organisms have been transported on hulls of vessels for centuries and in the ballast water of international shipping since the 1880’s (Byrne et al., 1997). The issue has received greater attention, however, as the impacts caused by some introductions have become apparent. The devastating effects of the zebra mussel Dreissena polymorpha in the Great Lakes (Griffiths et al., 1991; Strayer, 1991); the ctenophore Mnemiopsis leidyi in the Black Sea (Vinogradov et al., 1989); and, the clam Potamocorbula amurensis in San Francisco Bay (Carlton et al., 1990) have all increased concern internationally for the impacts of exotic species and lead to greater efforts to prevent further introductions. Unfortunately, identifying which species are likely to establish in new ecosystems is difficult, as is predicting their likely impact (Hengeveld, 1989). Victorian Government’s approach to threats posed by exotic species introduced into Victorian waters is outlined in Action Statement 100: “Introduction of exotic organisms into Victorian waters” issued under the Flora and Fauna Guarantee Act 1988. This action statement outlines the need for a risk-based approach and the need to develop a Victorian ballast water management system. Part of this management system involves assessment of the risk posed by all vessels that visit Victorian waters and this risk assessment requires information on exotic species already present in all Australian ports. This report presents the results of a field survey of exotic species within the Port of Melbourne. The Port of Portland (Parry et al.,1996), Port of Hastings (Currie and Crookes, 1997) and the Port of Geelong (Currie et al., 1998) have been surveyed previously. Therefore this report completes the initial survey of all four commercial ports in Victoria. All these surveys have used a sampling protocol developed by CRIMP (Hewitt and Martin, 1996), which involves the use of a variety of sampling techniques to sample a large range of habitats within the port area. Potential ‘pest’ species were targeted and sampling strategies were designed to detect species listed on the Australian Ballast Water Management Advisory Council (ABWMAC) marine target species list.
2.0 DESCRIPTION OF THE PORT OF MELBOURNE The Port of Melbourne is Victoria’s largest port and handles a greater volume of containers and general cargo than any other Australian port. Currently, the Port of Melbourne comprises 31 commercial berths spread across 11 docks, served by more than 40 shipping lines (Melbourne Port Corporation website). Over 3000 commercial ships visited the Port during 1998/99 moving over 21 million tonnes of cargo (Melbourne Ports Corporation, 1999). In 1999, container ships in the Port travelled directly to or from 200 different international and domestic ports (Melbourne Port Corporation website). The Port of Melbourne is located on the Yarra River at the north of Port Phillip Bay, approximately 60km from the open ocean. The Port of Melbourne boundaries extend from the Bolte Bridge, down the Yarra River and into Port Phillip Bay, almost to the southern end of the Port Melbourne Channel, enclosing approximately 20 km2 of water. The Port of 4
MAFRI Report No. 25
Melbourne also includes an inner and outer anchorage, three anchorages for vessels carrying dangerous cargoes and a spoil ground located ~15 km south of the Yarra (Figure 1). Nine of the 11 commercial docks that operate within the Port of Melboune were surveyed during this study (Table 1). Yarraville and South Wharves were the two docks not surveyed as adjacent wharves were surveyed (Maribyrnong and Appleton) and few differences were observed between all docks surveyed within the Yarra River. Princess Pier, which is condemned and no longer in use, was also surveyed because of the combination of its age, the unusual shipping activity it supported in the past (mostly naval and passenger vessels) and the markedly different environmental conditions in Hobsons Bay, compared to the Yarra River. The area encompassed by the Port of Melbourne is much altered from its natural state. The construction of the Coode canal, the removal of the bar at the river mouth and reefs around Spencer and Queen Streets in the 1880’s and the continued dredging of shipping channels have greatly increased the depth of the lower reaches of the Yarra River. These changes have probably reduced the range of habitats originally present in the lower reaches of the Yarra/ Maribyrnong River system. Prior to dredging, the Yarra River was probably 6m deep with a shallow bar at the mouth (Poore and Kudenov, 1978). The delta of the Yarra River once occupied approximately 90 km2 but the area of delta has since been halved (Watson 1972). Much of the original aquatic fauna and flora of the area has probably been lost (Poore and Kudenov, 1978). Port environments are often highly modified and disturbed, which may make them more susceptible to successful introductions (Fox and Fox, 1986; Vermeij, 1991). However the roles of disturbance versus the properties of native species and propagule pressure from exotic species in facilitating the establishment of exotic species are still being actively debated by ecologists (e.g. Lonsdale 1999). Today, the lower reaches of the Yarra River and parts of Hobsons Bay form a turbid, temperate estuary with limited tidal movement. Mean tidal amplitude is 0.2 m at Williamstown with mean tidal currents of 0.02 m/s, though currents are predominantly wind driven (Harris et al., 1996). Annual flow rates for the Yarra River from 1990 to 1995 ranged between 18.3-39 m3/s, though flow is highly seasonal (Harris et al., 1996). The discharge from the Yarra River can form a buoyant plume that differs from ambient seawater in salinity and temperature, if river flow is sufficient. The exact behaviour of the river plume depends on prevailing wind and weather conditions and river flow rates, though it generally travels down the east coast of Port Phillip Bay (Harris et al., 1996). With high river discharges, the waters of Hobsons Bay can become stratified, though bottom waters always maintain essentially marine salinities. River flows also have a major effect on the hydrochemistry and water quality of the Yarra River and Hobsons Bay (Walker et al., 1998). Hobsons Bay is supplied with silt and sand sediments from the Yarra/ Maribyrnong River system (Hinwood et al., 1979). These sediments lie over the Port Melbourne sands (observed to the west of the shipping channel), which overlay Coode Island silts that were deposited 8 800 years ago and have been exposed by dredging (Hinwood et al., 1979). Sediments around the mouth of the Yarra River and in deeper water are poorly sorted; better sorted sediments occur in the shallow regions of Hobsons Bay. The mean grain size of sediments range from 1 to 4 phi (Link, 1967). Poore and Kudenov (1978) suggest that the Yarra River has a highly predictable benthic fauna with low diversity while the fauna of Hobsons Bay is more diverse but less predictable.
Exotic Species in Port of Melbourne
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2.1 Port development British ships first visited Port Phillip Bay in 1802 (Kerr and Kerr, 1979). In 1803, Charles Grimes explored the Yarra and Maribyrnong Rivers, 32 years before Batman and Fawkner established Melbourne (Ruhen, 1976). Shipping traffic in Port Phillip Bay between 1802 and 1935 was limited but following the establishment of Melbourne, marine trade routes were quickly established. By 1839, intra and interstates routes, and international routes to Great Britain and New Zealand were established (Campbell and Hewitt, 1999a). However, ships with a draft greater than ~2.5 m had difficulty entering and navigating the Yarra River because of a shallow bar at the river mouth. Large vessels anchored in Hobsons Bay or at Sandridge Pier, where smaller vessels or “lighters” were used to carry passengers and goods up the Yarra River to Melbourne (Melbourne Port Corporation website). Cole’s Wharf , the first substantial Yarra wharf, was built between King and Spencer Streets and was eventually absorbed into Queen’s Wharf (Ruhen, 1976). Channel markers and lighthouses were built and in 1840 rules were introduced to govern the discharge of dry ballast (Kerr and Kerr, 1979). Dredging commenced in the 1850’s (Kerr and Kerr, 1979) and more piers were built, including Railway Pier at Sandridge (Station Pier) and Williamstown (U’Ren and Turnbull, 1983). A graving (dry) dock was built in the 1860’s (Cook, 1958). As volumes of traffic increased, especially with the discovery of gold in 1850, calls were made for the removal of the bar at the river mouth and dredging to further deepen the channel. After much deliberation, work on removing the river mouth bar and reefs around Spencer and Queen Streets, as well as widening, deepening and straightening the river (construction of the Coode canal) were undertaken and completed in the 1880's (Melbourne Port Corporation website; Ruhen, 1976). Victoria Dock, next to the railway yards, was in service by 1893 and handling most of Victoria's imports by the early 1900's. In 1910, dredging commenced on the shipping channel to Railway Pier (Station Pier) and, the proposed, New Railway Pier (Princess pier) at Port Melbourne. A 1914 report by Walsh also recommended the extension of the Port Melbourne Railway Pier, the construction of Appleton Dock, extension of the Williamstown piers and the addition of a central pier at Victoria Dock (Ruhen, 1976). At this time, the depth to which the Yarra River could be dredged was limited by the depth of the Spotswood sewer. Appleton Dock, built on the site of the old river course and finally completed in 1956, was able to handle ships with a 32 foot draft (Ruhen, 1976). Container ships were introduced to Melbourne in 1965 and roll-on roll-off ships followed. This changed the requirements of ports; storage sheds gave way to open wharves with large areas assigned for storage (Ruhen, 1976). In 1966, the first berth at Swanson dock was completed and Webb Dock was also expanded. Ironically, after the removal of the shallow bar at the mouth of the Yarra River, shipping access to the docks around the Melbourne CBD has been increasingly limited by bridges over the Yarra River. Princess Bridge and Queen Street Bridge were built prior to the 1920's. A further 1.3km of wharf was lost when Spencer Street Bridge was completed in 1928. Sir Charles Grimes Bridge in 1975 limited access to North Wharf and the construction of Bolte Bridge in 1999 closed Victoria Dock to commercial shipping.
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MAFRI Report No. 25
2.2 Shipping movements and vessel ballasting patterns The movement of shipping in all four Victorian ports between August 1994 and July 1995 was documented by Walters (1996), which is the source of the following summary. The Port of Melbourne received the highest number of ship visits of any Victorian port, more than three times the total visits at the other three commercial ports combined. The vast majority of ships to visit Melbourne arrived from a domestic last port of call, though many of these ships were international ships with multiple Australian ports of call. These international ships carry ballast from overseas and from other Australian ports. The Port of Melbourne, however, received only the second highest amount of ballast water (1.4 million tonnes) of any Victorian Port, approximately 70% of which was of domestic origin. The volume of ballast water discharged is low compared to the number of ships visits because of the large number of container and roll-on roll-off vessels which use the Port of Melbourne, the even mix of imports and exports which these particular ship’s carry, and the low proportion of ship visits from exporting bulk carriers. The Port of Melbourne receives large volumes of international and domestic shipping and is therefore vulnerable to the establishment of exotic species directly from overseas and from other Australian ports. Of the ship visits to the Port of Melbourne with an international last port of call, nearly half arrived from New Zealand. Domestically, both the number of ship visits and the volume of ballast received was greatest from Sydney, though a considerable amount of ballast was also received from South Australia. As sixty eight percent of ships visiting Melbourne have a domestic next port of call, Port Phillip Bay is an important potential source of secondary introductions to other temperate Australian ports. Sydney, Burnie, Adelaide and Brisbane account for 71% of the domestic destinations from the Port of Melbourne. 2.3 Pile construction and cleaning Undisturbed communities of competitive dominants are believed to be more resistant to recruitment of other species (Vermeij, 1991). Wharf piles may be the primary site of establishment for hull fouling species, especially if piles have been recently cleaned or replaced and have a large percentage of available free space. The construction material of these piles (Table 1) may also influence the provision and suitability of unoccupied space and hence the invasibility of the port environment. The Port of Melbourne does not routinely remove fouling from the support piles and columns of its wharves. Divers periodically scrape fouling organisms from piles to determine their structural integrity and whether they need replacement. The intertidal area and the bottom metre above the seabed on piles are targeted during inspections as these are the areas prone to deterioration (Bill Johnson, Melbourne Ports Corporation, pers comm).
Exotic Species in Port of Melbourne
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2.4 Channel dredging and dredge spoil removal Dredging has been observed to translocate exotic species within a port (Carlton et al., 1990). From early times in the Port of Melbourne, regular dredging has been required to counteract siltation at the mouth of the Yarra and Maribyrnong Rivers, and to increase the depth of water as the draft of trading vessels has increased. The largest volumes of fine sediments dredged in Victoria are from the Port of Melbourne. Prior to the 1870’s, spoil was deposited at the entrance to Hobsons Bay (presumably near Point Gellibrand) (Ruhen, 1976). According to the Admiralty Surveyor, in southerly gales this spoil was resuspended and deposited around the mouth of the Yarra River, accelerating shoaling by one to three feet per year. However, another commissioned survey suggested that the rate of deposition was less than 3 inches per year and mostly attributable to sediments washed down the Yarra River, which at this time were being accelerated by land clearing and the growth of Melbourne (Ruhen, 1976). In 1882, a temporary embargo was placed on the deposition of dredge spoil in Laverton Bay (presumably Altona Bay), creating problems once land fill sites had been fully utilised (Ruhen, 1976). The current spoil ground is located 8 nm (15 km) south of Williamstown (Figure 1). The boundaries of the 9.3 km2 spoil ground were defined in 1947, although the general area was in use before March 1929. The Port of Melbourne Authority records show that between 1877 and 1982 nearly 100 million m3 of spoil were dredged from the Yarra and Maribyrnong Rivers; 23 million m3 from Williamstown; and, 45 million m3 from the Port of Melbourne facilities located in Hobsons Bay. Only a small fraction of this total was used for land reclamation with nearly 86% deposited in deep water, presumably in or around the location of the current spoil ground. Today, the greatest maintained depth is 13.1 m at Swanson and Holden Oil Docks, though the Port Phillip South Channel restricts draft to 11.6 m or up to 12.1 m with the tide (Hinksman, Victorian Channels Authority, pers comm). Maintenance dredging within the Port of Melbourne removes about 200 000 m3 per annum (Coleman et al., 1999).
3.0 EXISTING BIOLOGICAL INFORMATION Port Phillip Bay and the Port of Melbourne have been well studied in comparison to other areas and ports in Australia. In 1957, the National Museum of Victoria and the Fisheries and Wildlife Department commenced an ecological survey of Port Phillip Bay that examined geology, geomorphology, bottom sediments, algae and the taxonomy of several invertebrate phyla. The results of this study were published in two volumes of the Memoirs of the National Museum of Victoria (No. 27, 1966 and No. 32, 1971). However, only one dredge station was located within Hobsons Bay near the Port of Melbourne (station 201). During the period 1967-1971, the Melbourne and Metropolitan Board of Works and the Fisheries and Wildlife Department of Victoria undertook a quantitative environmental survey of Port Phillip Bay (MMBW and FWD, 1973). Biological considerations in this later study included surveys of phytoplankton, zooplankton, zoobenthos, fish and bacteria. No stations, however, were positioned within Hobsons Bay. A further environmental survey was undertaken between 1993-1996. The Port Phillip Bay Environmental Study included studies of the chemistry and nutrient processes of the water column and sediments, phytoplankton, zooplankton, algae and benthos (Harris et al., 1996). Coleman et al. (1999) provide a recent review of Port Phillip Bay habitats and their history of disturbance.
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MAFRI Report No. 25
The behaviour of the Yarra plume in the Port of Melbourne was examined during the Webb Dock Study (1976-1977) (Hinwood et al. 1979). A number of other studies have directly investigated the fauna and flora of Hobsons Bay and the Yarra River. The most recent studies relevant to the Port of Melbourne include: the Heated Effluent Study (1973-1976) (Sandiford and Holmes 1982) and the Webb Dock Environmental Effects Statement in 1998 which investigated fish, infaunal and epibenthic communities, as well as toxicants in biota and sediments (Walker et al., 1998). A bay-wide survey of exotic species, which included stations within the Port of Melbourne, was published as part of a review of exotic species known to occur in Port Phillip Bay (Campbell and Hewitt, 1999b). 3.1 Phytoplankton Wood (1964) was the first to consider phytoplankton populations in Port Phillip Bay and to document the dominant species. This early taxonomic research was the basis for a quantitative survey of phytoplankton distribution in Port Phillip Bay during 1970/71 (MMBW and FWD, 1973). In this study, phytoplankton and zooplankton were monitored at a site near Point Gellibrand and 23 stations throughout the rest of Port Phillip Bay. A total of 114 taxa were identified in this survey, most of which were diatoms. No ABWMAC target exotic species (Gymnodinium catenatum and Alexandrium spp.) were detected during the survey. The Heated Effluent Study of 1973-1976 and the Webb Dock Study of 1976-1977 were the first to record diatom blooms in Hobsons Bay, in response to discharges from the Yarra River (Harris et al. 1996). A. catenella was first discovered in Hobsons Bay in 1986 (Hallegraeff, 1987) and has subsequently bloomed within the bay in 1986, 1988, 1991 and 1992 (Wood and Beardall, 1992). Similarly, a bloom of A. tamarense was observed in 1993 (Harris et al.,1996). The most comprehensive survey of phytoplankton in Port Phillip Bay was undertaken by MAFRI as part of a Shellfish Sanitation Program. This survey involved sampling at seven bay wide sites, approximately every two weeks, between July 1987 and December 1996. A total of 282 species of phytoplankton were recorded across Port Phillip Bay, including the exotics A. catenella, A. minutum, A. tamarense which occurred throughout the bay (Table 3, Arnott et al., 1999). Four public health alerts have been issued for Hobsons Bay and surrounding waters since 1988 for paralytic shellfish poisoning (PSP) blooms, suggesting that cysts were likely to be abundant in the sediments (Sonneman, 1992; Sonneman and Hill, 1997; Arnott et al., 1994). The Webb Dock Environmental Effects Statement recorded high numbers of A. catenella cysts in the sediments of Webb Dock (600 cysts g-1) and Hobsons Bay (322-835 cysts g-1) but few in the Yarra River (Walker et al., 1998). Gymnodinium catenatum has not been recorded in Port Phillip Bay away from the heads, but has been recorded around the heads and along the open coast of Victoria (Sonneman and Hill, 1997). 3.2 Benthic flora Womersley (1966) examined the distributions of subtidal algae collected throughout Port Phillip Bay between 1957/63 and noted that Ulva lactuca was widespread within the bay. Lewis (1999) comprehensively reviewed the exotic macroalgae present within Port Phillip Bay. He lists 16 macroalgae considered to be introductions to Port Phillip Bay, though he did not include Ulva lactuca in this category. He lists another seven species that are possible introductions to southern Australia but have yet to be found in Port Phillip Bay. Lewis (1999) Exotic Species in Port of Melbourne
9
suggests a number of life history traits may be common to species which have established in distant locations including broad physiological tolerances, fast growth rates, high fecundity and regeneration ability. 3.3 Benthic fauna Only one dredge station (201) from the 1957 ecological survey of Port Phillip Bay was located within Hobsons Bay. Four species were collected at this station but none were exotic species. Watson (1972) studied the benthos of Hobsons Bay in relation to the thermal discharges of the Newport power station for the State Electricity Commission, recording only 90 species, but many of these were very abundant. Six species were exotic including Carcinus maenas, Ciona intestinalis, Styela plicata, Theora lubrica, Myxicola infundibulum and Ulva lactuca. Poore and Kudenov’s (1978) study of the benthos of the Port of Melbourne in 1975 recorded 248 species, though the stations in the Yarra River were species poor in comparison to the sandy and muddy Hobsons Bay stations. The most abundant species in their study was the exotic tellinacean bivalve Theora lubrica (recorded as T. fragilis), which reached maximum densities 2.5 km upstream from the mouth of the Yarra River. The Webb Dock studies in 1977 (Hinwood et al., 1979) and 1998 (Walker et al., 1998) also documented the infauna of the Port of Melbourne. The 1998 study recorded 115 infaunal species. Theora lubrica was the most abundant species and Corbula gibba was the sixth most abundant species. Other exotics collected included Euchone limnicola, Pyromaia tuberculata, Musculista senhousia, Myxicola infundibulum and Sabella spallanzanii. Walker et al. (1998) suggested that the dominance of T. lubrica may have spread into Hobsons Bay. 3.4 Demersal Fish Demersal fish communities were intensively sampled at 19 stations throughout Port Phillip Bay between 1969 and 1972 (MMBW and FWD, 1973). All sixty-eight fish species collected during this trawling program were native to southern Australian waters. A 1982/83 survey of recreational fishing catches in Port Phillip Bay (MacDonald and Hall, 1987) also failed to detect any exotic fish species, however the identities of many species collected in this survey could not be reliably confirmed. During an investigation into changes in demersal fish communities in Port Phillip Bay between 1970 and 1991, Hobday et al. (1999) recorded Acanthogobius flavimanus in shallow water north of Point Richards in 1990/91. Demersal fish populations in Port Phillip Bay have subsequently been surveyed almost annually since 1990 by MAFRI. The autumn trawl program samples 22 depth-stratified stations within Port Phillip Bay, including one station in Hobsons Bay (7m depth) and another near the spoil ground (12m depth). In 1991, three Japanese yellow-fin gobies A. flavimanus were collected from the Corio Bay station (Parry et al., 1995). A. flavimanus has not been collected at any of the trawl stations since, nor have any other exotic fish species been collected in trawl samples subsequently. The Webb Dock Environmental Effects Statement recorded 22 species of fish including the exotic gobies, A. flavimanus and Tridentiger trigonocephalus (Walker et al., 1998). Four species of exotic fish (A. flavimanus, A. flaumi, T. trigonocephalus and Forsterygion lapillum) have been recorded in Port Phillip Bay (Lockett and Gomon 1999), but F.lapillum has not been recorded in the Port of Melbourne, although it is abundant near Geelong 10
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(Matthew Lockett, pers comm). Dietary studies of thirty-five fish species collected during the annual trawl surveys in Port Phillip Bay have also revealed three exotic species (Parry et al., 1995). The European clam Corbula gibba was present in the diets of nine indigenous fish species. The exotic spider crab Pyromaia tuberculata was found to be a minor component in the diets of eight fish species while the Asian bivalve Theora lubrica was a minor component in the diets of greenback flounder and red gurnard.
4.0 SURVEY METHODS The survey methods used in this survey are summarised in Table 2a and the sites at which each method was used are summarised in Table 2b. These methods follow closely the protocol established by Hewitt and Martin (1996), except that we used additional methods to sample infauna and small scavenging animals. Benthic infauna was sampled using cores (as proposed by Hewitt and Martin, 1996) and using Smith-McIntyre grabs. Three types of traps (Crab, shrimp and scavenger) were used in this survey, whereas Hewitt and Martin (1996) proposed only the use of crab and shrimp traps. An Ockelmann sled was used rather than a roller-beam trawl, but these methods are recognised as alternatives by Hewitt and Martin (1996). Poison was not used to sample small fish in our survey, but small fish were captured in traps and seine nets. Sampling sites were selected to include the busiest wharves and to ensure that collectively the widest range of habitat types in the port were sampled. In particular sampling sites extended from the wharf furthest upstream in the Yarra River (Victoria Dock) to port facilities in the most marine part of Hobsons Bay (Breakwater and Station Piers) so that habitats spanning the full range of salinities were sampled. Phytoplankton samples were examined live by Dr. Steven Brett or Dr. David Hill of Brett Water Science Pty. Ltd. The identities of all species collected have been confirmed by sending reference collections to taxonomic experts for identification and to ensure consistency of identification across institutions. Crustaceans, polychaetes, fishes and molluscs were examined by Drs Gary Poore, Robin Wilson, Martin Gomon and Ms Sue Boyd of the Museum of Victoria. Bryozoans were examined by Dr Phillip Bock (RMIT University), sponges by Dr Jane Fromont (W.A. Museum), ascidians by Dr Patricia Mather (Queensland Museum) and algae by Dr Gerry Kraft (Univ of Melbourne). A collection of all species for which more than a single specimen exists will be sent to Centre for Research into Introduced Marine Pests (CRIMP). 4.1 Phytoplankton Sediment cores for cyst-forming species were taken by divers using 20 cm long plastic tubes with a 25 mm internal diameter. Three sediment cores were taken at the base of a single pylon at each dive site. Sediment tubes were capped with bungs and stored upright in a refrigerator or on ice. Sediment (1.25 ml) from the top 2 cm of each core was initially sieved through a 100 µm sieve to remove large sediment particles and detritus. The algal cysts were then collected on a 20 µm sieve, identified and counted using a Sedgwick-Rafter counting chamber Exotic Species in Port of Melbourne
11
Qualitative phytoplankton samples were collected using a 20 µm plankton net, and quantitative phytoplankton samples were collected using a 1 litre plastic bottle. All samples were stored in a refrigerator or on ice until they were delivered to Brett Water Science, except for the April 2000 samples which were preserved in formalin. Qualitative phytoplankton samples were collected from Station Pier (3 net tows) and Pier 35 (3) during winter, August 1999, and from Victoria (2), Appleton (4), Swanson (2), Webb (2), and Maribyrnong (2) Docks and Breakwater Pier (2) during autumn, 13 or 14th Apr 2000. Quantitative phytoplankton samples were collected from Pier 35 (3 x 1 L samples) on 5 August, 1999 and from Appleton (1), Swanson (1), Webb (1), Maribyrnong (1) and Holden (1) docks and Breakwater Pier (1) on the 18 May 2000 (Figures 2-9). 4.2 Trapping Trapping was conducted using traps of three different designs, intended to catch crabs, shrimp and scavenging organisms. The largest traps were oval-shaped “Opera-house” crab traps (65 × 46 × 23 cm) covered in 2 cm mesh net. Shrimp traps were rectangular (43 × 25 × 25 cm) and covered in fine 2-5 mm mesh net. The scavenger traps were constructed of a 35 cm length of 10 cm diameter PVC pipe with a funnel at one end and a 1mm mesh cover over the other end. A set of 3 traps (crab, shrimp, scavenger) were baited with fish and deployed overnight at up to five different locations at each site. Traps were deployed at Station Pier and Webb Dock on the 3rd of August, 1999, and at Breakwater Pier, Swanson, Webb, Maribyrnong, Holden, Appleton and Victoria Docks on the 13th and 14th of April, 2000 (Figures 2-9). 4.3 Diver observations and collections on wharf piles Semi-quantitative sampling was undertaken on three piles at each dive site. Unlike previous MAFRI port surveys where every third pile was sampled, consecutive piles were sampled to limit diver ascents as poor visibility at most sites created difficulties swimming between piles. A bungee cord was used to fix a weighted rope, marked to indicate depth, to each pile at the low water mark. A Panasonic NV MS95 SVHS video camera recorded the marine fouling on a single pile at each dive site. Care was taken to include the weighted rope, as well as the tags recording locality information for the still photography, in the video. At depths of 0.5 m, 3 m and 7 m, one photograph of fouling organisms (14 ×17 cm in area) was taken using a Nikonos Mark IVA underwater camera fitted with a 28 mm lens and framer. An area 30 × 40 cm, that included the area photographed, was then scraped with a dive knife in to a mesh bag (10mm). Samples were subsequently fixed in 10% formalin, except for sponges which were preserved separately in 70% alcohol to prevent the loss of spicules (a critical taxonomic character). All species from approximately half of the scrapings were identified and counted in the laboratory (Victoria, Appleton, Swanson West 3, Webb West and Webb 5 East docks and Gellibrand and Station piers). Only the larger fouling organisms were identified and counting from the remaining samples (Breakwater and Princess piers and Swanson West 1 and 2, Swanson East 4, Maribyrnong, Holden and Webb 4/5 East and 2/3 East docks) with the remaining fauna and flora being archived. Victoria, Appleton and Webb Dock, Gellibrand and Station Piers were sampled in winter between the 3rd and 5th of August 1999. Swanson, Maribyrnong and Holden Docks, Breakwater and Princess Piers were sampled in summer between the 9th and 16th of February, 2000 (Figures 2-9). 12
MAFRI Report No. 25
4.4 Visual searches Divers were instructed to look for macro-exotic species at each dive site, outside the areas scraped of fouling organisms. However, poor visibility at most sites limited the extent and success of these visual searches. Extensive boat-based visual searches were undertaken to determine the geographical spread of Undaria pinnatifida within the Port of Melbourne, between St Kilda Marina and the breakwater at Williamstown on the 4th of August, 1999. 4.5 Benthic infauna Benthic infauna was sampled using a 0.1 m2 Smith-McIntyre grab and divers using cores with an internal diameter of 103 mm. Grab samples were taken at 65 sites throughout the Port of Melbourne, including the spoil ground (Figure 10), between the 7th-9th of December, 1999. Nine samples were taken at sites surveyed by Poore and Kudenov (1978) (Figure 10, grabs 2, 6, 9, 10, 12, 15, 25, 27-28) and the remaining sites sampled a wide geographical range and a wide range of sediment types and hydrodynamic conditions. Chemical and sediment granulometry samples were removed from the grabs prior to sieving, stored in 100 ml whirlpacks and frozen until they were ready to be processed. All grab samples were rinsed on a 1 mm mesh sieve and preserved in 10% formalin. Fauna were later identified to species and counted under a dissecting microscope. A third of the sediment sample was dried in an oven at 50°C, then placed in a muffle furnace at 500°C for two days to determine the organic content of the sediment. Another portion of the sample was wet sieved to determine the fraction less than 63 µm (silt). Three cores were collected by divers near the base of one pile at each dive site. Cores were taken at Victoria, Appleton and Webb Docks, Gellibrand and Station Piers during winter (3-5 August 1999), and at Swanson, Maribyrnong and Holden Docks, Breakwater and Princess Piers during summer (9-16 February 2000) (Figures 2-9). Processing of infauna from core samples was identical to that for grabs. 4.6 Epibenthos Epibenthos was sampled with an Ockelmann sled fitted with a 1.0 cm mesh liner and towed for 5 minutes at each site. Samples, or sub-samples of the larger shots, were retained and fixed in 10% formalin. All organisms present in the samples were later identified, counted and weighed in the laboratory. Nineteen of the proposed 30 stations were sampled on the 8th and 9th of December, 1999 before the Ockelmann sled was lost after retrieval of sample 7. Stations 8-17 were not sampled (Figure 11). 4.7 Seine netting A 10 mm mesh seine net, 60 m long and 1.25 m high, was used to sample inshore fish. Only three locations were sampled due to the limited extent of suitable sampling sites within the Port of Melbourne. At each of these locations, the net was shot once during daylight and once at night. Most fish caught in the net were identified to species and counted in the field. Fish that could not be reliably identified in situ were fixed in 10% formalin and later examined under a Exotic Species in Port of Melbourne
13
dissecting microscope in the laboratory. Seine netting was conducted at the mouth of the Moonee Ponds Creek (Figure 3), and Sandridge Beach (Figure 9 & 11) and Webb Dock Beach (Figure 7) between the 13th and 14th of April, 2000.
5.0 SURVEY RESULTS 5.1 Exotic Species in Port Exotic species found at each of the docks and piers in the Port of Melbourne are listed in Table 4. Summaries of the mean number and percentage occurrence of all species found in the survey (except phytoplankton), by sampling methods, are given in Appendices 1 and 2. During the survey, particular attention was paid to species listed on the Australian Ballast Water Management Advisory Council (ABWMAC)’s marine target species list, which includes the following species: Species name
Common name
Native and Introduced Regions
Organisms that are already in Australia Alexandrium catenella Alexandrium minutum Alexandrium tamarense Gymnodinium catenatum Asterias amurensis Carcinus maenus Corbula gibba Crassostrea gigas (Feral) Musculista senhousia Sabella spallanzanii Undaria pinnatifida
Toxic dinoflagellate Toxic dinoflagellate Toxic dinoflagellate Toxic dinoflagellate Northern Pacific seastar European shore crab European clam Pacific oyster Asian date mussel Mediterranean fanworm Japanese seaweed
Japan, Russia, Korea Europe Europe Asia China, Taiwan, Philippines Mediterranean Japan
Organisms that have not yet arrived in Australia but pose a significant threat Caulerpa taxifolia spp 2 Dreissena bugensis Eriocheir sinensis
Algae (Aquarium hybrid) Quagga mussel Chinese mitten crab
Hemigrapsus sanguineus Mnemiopsis leidyi
Asian crab Comb jelly
Philine aurioformis Potamocorbula amurensis Sargassum muticum
New Zealand sea slug Asian clam Japanese seaweed
Mediterranean Europe, North America China, Taiwan, Japan, Europe, North America China, Taiwan, Japan, West Atlantic West Atlantic, Black and Azov Seas, Eastern Mediterranean New Zealand, North America China, Taiwan, North America China, Taiwan, Japan, Eastern Pacific, Atlantic Europe
2
Caulerpa taxifolia has recently been discovered in New South Wales (Septemeber 2000) and is currently known from at least three locations (Pittwater, Port Jackson and Lake Conjola). 14
MAFRI Report No. 25
5.11 ABWMAC target introduced species Alexandrium and Gymnodinium (Toxic Dinoflagellates)
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Alexandrium catenella, A. minutum and A. tamarense were all recorded in Port Phillip Bay during phytoplankton surveys of shellfish growing areas undertaken between July 1987 and December 1996 (Table 3, Arnott et al., 1990). Alexandrium catenella was the most frequently observed of these three Alexandrium species and it was the only species more abundant in the port/Hobsons Bay area. A. minutum was only recorded rarely and A. tamarense was uncommon but widely distributed in Port Phillip Bay. Gymnodinium catenatum was not recorded in Port Phillip Bay. Several other species of Alexandrium and Gymnodinium have also been recorded in Port Phillip Bay (Table 3). A. compressum is not known to be toxic, and, as they appear as slightly flattened forms of A. catenella, the infrequent records of A. compressum may be aberrant forms of A. catenella (S. Brett, pers comm). A. ostenfeldii is known to be slightly toxic (S. Brett, pers comm), but has been observed only rarely (Table 3). The only strain of A. margalefii to be tested was non-toxic, but this species may be implicated in a toxic event in Tasmania (Hallegraeff et al. 1991). A. margalefii has always been uncommon in Port Phillip Bay (Table 3). A. pseudogonyaulax is not known to be toxic (S. Brett, pers comm), and has only been observed rarely in Port Phillip Bay (Table 3). Gymnodinium mikimotoi and G. Exotic Species in Port of Melbourne
15
pulchellum are known to cause fish kills (Wood and Beardall, 1992), while G. sanguineum is not known to produce toxins but is recorded as a nuisance “red-tide” species (S. Brett, pers comm). G. breve has been recorded rarely in Port Phillip Bay and while this species is known to cause toxic blooms in Florida, the toxicity of the local strain is uncertain (S. Brett, pers comm). Alexandrium catenella and A. tamarense were collected from every wharf surveyed except Pier 35 during this survey (Table 5). A. catenella was the dominant dinoflagellate in phytoplankton samples collected in April and, in contrast to the samples collected in May, a significant proportion of cells were organised into healthy chains. Alexandrium spp. cysts were present in sediment samples from every wharf surveyed except Gellibrand and Station Piers (Table 6). These cysts were probably A. catenella, though germination is necessary for a unequivocal identification. No planktonic or cysts of Gymnodinium catenatum were collected in phytoplankton or sediment samples (Tables 5, 6). The native species Dinophysis acuminata, which can cause diarrhoretic shellfish poisoning and was common in the bay during the Phase 1 study (Arnott et al., 1990), was an important component of the dinoflagellate flora at all sites surveyed except for Pier 35 and Holden Oil Dock (Table 5). Pseudo-nitzschia spp, known to cause amnesic shellfish poisoning, were abundant in the water column in the Port of Melbourne in samples collected during April (Table 5). Rhizosolenia cf. chunii which can cause a bitter taste in mussels (Parry et al., 1989) was collected in samples from Maribyrnong No. 1 berth, Holden Oil Dock and Breakwater Pier (Table 5). Gymnodinium mikimotoi and G. pulchellum were not observed.
Asterias amurensis (Northern Pacific seastar)
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This species of seastar is native to the northern Pacific and is thought to have been introduced into Tasmania via ships ballast water in the early 1980’s (Morrice, 1995). The current known distribution includes the Derwent Estuary in southeastern Tasmania (Byrne et al., 1997) and Port Phillip Bay. Infestations of Asterias are believed to have virtually eliminated bivalve 16
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MAFRI Report No. 25
mollusc populations in the Derwent River, Tasmania (AQIS, 1994). In Port Phillip Bay, the first two adult Asterias were collected in scallop dredges near Point Cook (August 1995) and Portarlington (23 cm diam., August 1996). During April 1997, another mature Asterias was collected by divers at Victoria Dock in the Port of Melbourne. On all three occasions, subsequent searches failed to locate any further individuals. In January 1998, four juveniles (34 cm diam.) were found on mussel ropes on a commercial shellfish lease off Dromana. These long-lines had not been in direct contact with the seafloor and the animals found could only have settled on the mussel ropes as larvae, indicating that a breeding population of Asterias had established in Port Phillip Bay. Asterias is now very abundant in north eastern Port Phillip Bay (pers obs) and throughout the Port of Melbourne. Over 300 individuals were collected during this survey. The starfish were caught by every sampling method used in the survey, except phytoplankton nets. One individual was collected in a core from Princess Pier, where the divers estimated the density of starfish on the seabed at ~10 m-2. Three individuals were collected in pylon scrapings, one each at Princess, Station and Webb docks. Four individuals were collected using the beach seine net from Webb Dock and Sandridge beaches. Most were collected in the epibenthic sleds (228), traps (98 in all 3 types) and grabs (11). Starfish were collected from every wharf except Victoria Dock, where an isolated individual was first observed in 1997. Starfish captured in and around the Yarra River were predominately small individuals spawned during the winter of 1999. Most Asterias in Port Phillip Bay occur in water deeper than 15m (Parry, unpublished data). In the Port of Melbourne, however, Asterias are abundant in very shallow water (
