CRC REEF RESEARCH CENTRE TECHNICAL REPORT No. 35

Sample collection methods and practical considerations for introduced species' surveys at tropical ports.

Frank Hoedt, James Cook University
Howard Choat , James Cook University
Juan Cruz, James Cook University
John Collins, James Cook University

FOREWORD

The School of Marine Biology and Aquaculture at James Cook University is a partner in the CRC Reef Research Centre Ltd. It is interested in all aspects of the management of the marine environment as well as maintaining a first class research capability. The Ports Corporation of Queensland (PCQ) is responsible for the management and operation of eight major ports on the Queensland coast and a major part of these responsibilities is to maintain the environmental integrity of ecosystems in and around these ports. As part of PCQ's EcoPorts program, systematic surveys are underway to search for exotic marine organisms that have been imported through international shipping movements.

In 1998, discussions between PCQ and CRC Reef identified there would be mutual benefits if an arrangement could be put in place whereby CRC Reef could carry out these surveys. PCQ would benefit by having the surveys carried out at a commercially competitive rate and CRC Reef would acquire a taxonomic capability that would enhance its research and teaching program. While PCQ commissioned CRC Reef to carry out the work on a commercial basis, it recognised and strongly supported the various research spin-offs and knowledge-base increases that would accrue as a result of the collection and classification of large numbers of local organisms.

It became clear that there were some particular considerations to be addressed to ensure adequate sampling in tropical ports. These included such things as the high diversity of organisms and sampling regimes, and not getting eaten by crocodiles. As a result, this report has been written to document the requirements of sampling in tropical ports so that a consistent approach can be taken that will allow temporal and spatial continuity of data sets. This will have much wider applications than just the sampling for exotic organisms, and both the Ports Corporation and the Marine Biology Department are pleased to have been involved with this work.
Derek Andrews
Chief Executive Officer
Ports Corporation of Queensland

EXECUTIVE SUMMARY

There is growing worldwide recognition of the detrimental impact of marine pest species in inshore waters. Most of the documented marine pest species in Australian waters are believed to have been transported through mariculture and shipping activities. In response to this problem, the Australian Association of Ports and Marine Authorities and the CSIRO Centre for Research on Introduced Marine Species (CRIMP) developed terms of reference for a nationwide series of baseline port surveys. CRIMP has written a set of guidelines for sampling methods for these surveys (Hewitt and Martin 1996) to ensure that the results of the port surveys are comparable. The Ports Corporation of Queensland's environmental program (Ecoports) is presently undertaking biological surveys of all of its Queensland ports to determine native biodiversity and detect introduced marine species.

In comparison with temperate waters, little is known about the presence and impact of exotic marine species in tropical Australian waters. Baseline knowledge of both endemic flora and fauna and any introduced species at ports is essential for future monitoring and management of the potential problem of introductions. Queensland coastal waters, which include the Great Barrier Reef, are part of biologically diverse marine zone known as the central Indo-West Pacific province. Monitoring of introduced species at potential points of entry is an important part of managing and protecting this unique coastline.

The first tropical port surveys in Australia were conducted by CRIMP in Hay Point and Mackay in Queensland in 1998. Subsequently, the School of Marine Biology and Aquaculture at James Cook University, on behalf of CRC Reef Research Centre Ltd undertook surveys at Mourilyan Harbour, Abbot Point, Lucinda, Weipa and Karumba. For these surveys, we adopted the methods of Hewitt and Martin (1996) but found it was desirable to implement some modifications to allow for the biological and environmental characteristics of tropical ports. We feel that some modifications are required for tropical ports so that sampling methodologies are appropriate for these environments. This report addresses the need for guidelines specific to tropical port surveys. It discusses the characteristics of tropical inshore marine communities and their habitats that are relevant to port survey planning and the sampling methods appropriate for these environments. Data from two of the surveys (Mourilyan Harbour and Abbot Point) are used as a basis for discussion in this report. The recommendations in this report can serve as a guideline for the ongoing surveys of tropical Queensland ports and will also provide a technical guide for biological/environmental surveys in tropical waters.

A number of environmental and biological characteristics of tropical inshore marine environments were identified as requiring consideration when planning biological collecting or monitoring programs in tropical ports. Warm temperature, the potential presence of dangerous marine animals, turbidity, habitat type and monsoonal seasonality need to be considered in relation to specimen handling, diving operations, and time of year and frequency of sampling. Biological characteristics of relevance included high species diversity and high biological process rates. High species diversity coupled with the lower proportion of described species of tropical Australian marine invertebrates compared with temperate species increase sorting and analysis time. The high rates of biological processes that characterize tropical waters will influence the frequency of ongoing monitoring.

Sampling devices recommended in Hewitt and Martin (1996) were for the most part effective. The methods for sampling hard substrate invertebrates (wharf pile scraping samples), crabs (traps), crab exuviae (beach surveys), fish (seine net), zooplankton (plankton nets), dinoflagellate cysts (sediment samples) and phytoplankton (plankton nets) successfully collected the target organisms. However, significant problems were encountered with aspects of the diver-mediated sampling and surveying, shrimp-trapping and beam trawl sampling and these methods need to be reappraised.

Diver sampling and surveying comprise a significant component of the recommended minimum sampling methodology in Hewitt and Martin (1996) but it is evident that for some tropical ports, alternative methods need to be considered. Soft-bottom surveying and sampling for epibenthic organisms by divers was problematic at both ports but particularly in the estuarine Mourilyan Harbour. Extremely limited visibility reduced the usefulness of diver surveying. Furthermore, safety risks unique to the tropics, such as the presence of estuarine crocodiles and marine stingers, warrant the reduction of diver sampling where possible in tropical ports, particularly in estuarine habitats.

An Ocklemann sledge was trialed at Mourilyan Harbour and Abbot Point as an alternative method to diver sampling of soft bottom epibenthic organisms. This device effectively collected a wide range of taxa in this habitat. The Smith-McIntyre grab was also trialed as an alternative to diver hand-coring to sample benthic infauna, dinoflagellate cysts and sediment samples. At Mourilyan Harbour and Abbot Point, the Smith-McIntyre grab successfully collected a large number of benthic infauna taxa. It also collected sediment samples for dinoflagellate cyst and sediment analysis. Furthermore, there was little overlap between the taxa collected in the Ocklemann sledge-dredge and the Smith-McIntyre grab.

Shrimp traps as recommended in Hewitt and Martin (1996) did not collect the target organisms at the two ports surveyed. Fortunately, other methods did catch shrimps; 11 and 19 taxa were collected at Mourilyan Harbour and Abbot Point, respectively in wharf pile scraping, benthic sled and Smith-McIntyre grab samples. Shrimp can also be sampled using other methods including light traps, fine mesh seine nets and push nets. Beam trawl catches at both ports were low in abundance and diversity, probably because the device was used in daylight hours. Subsequent night sampling yielded greater catches indicating that this device must be operated at night for optimal catches.

The adequacy of sampling intensity was examined by plotting cumulative species' curves for sampling devices used at the two ports. In some instances, the curves had not reached the asymptote indicating that the number of samples collected at tropical ports may need to be re-assessed for certain sampling gears.

A preliminary analysis of differences in taxonomic diversity indicates that tropical ports are more diverse than temperate ports. At Mourilyan Harbour (MH) and Abbot Point (AP), 401 and 593 taxa respectively were collected. The major component of time in processing samples was devoted to identification of specimens. The higher diversity in tropical ports increases the time needed to complete a biological survey.

We noted marked differences in community composition at the two ports surveyed. The biological assemblages at the two ports differed as a consequence of contrasting habitat types. Within two of the more diverse groups, the bivalve molluscs and polychaete worms (38 and 44 species of bivalve, and 125 and 166 species of polychaete were collected at MH and AP respectively), between 62% and 71% of the species in each group were found only at one port.

It can be difficult to identify tropical inshore marine invertebrates. The status of taxonomic knowledge for tropical Australian invertebrate groups is typically less than for their counterparts in temperate waters. This has two important ramifications. Firstly, a higher proportion of taxa cannot be identified to species level by taxonomic experts compared with temperate ports. Secondly, it is likely that a greater proportion of specimens in a tropical collection will require the assistance of taxonomic specialists for identification. Tropical port surveys conducted in collaboration with taxonomic specialists represent a unique opportunity to increase the existing knowledge of tropical marine invertebrate taxonomy.

A feature of tropical systems that should be considered when planning the timing of surveys for monitoring introduced species are the monsoonal seasonal changes in environmental conditions and consequently, community structure. Given the high rate of biological processes in the tropics which can translate into rapid colonisation by introduced species, it is recommended to continue regular cost-effective monitoring of ports.

THIS PUBLICATION IS CITED AS:
Hoedt, FE, Choat, JH, Cruz, JJ, Collins, JD. (2001)
Sample collection methods and practical considerations for introduced species' surveys at tropical ports
CRC Reef Research Centre Ltd
Technical Report No. 35.
Townsville; CRC Reef Research Centre Ltd, 41 pp.

ISBN 1 876054 58 1

A full hard copy of this report may be obtained from the author(s) or through the following libraries: