Port baseline study, pest biota
Port baseline study - Port of Brisbane
In Queensland the vast diversity of tropical and sub-tropical environments has made it difficult to assess the number and types of naturally occurring species and population statistics. Also, there is little information on marine biota and most Queensland ports have not been surveyed for the presence of exotic species until recently.
The proposed studies will identify the native flora and fauna and also identify the presence of any target organisms. Information will also be used in management strategies to protect our marine biodiversity. Potential impacts of introduced exotic species into our environment have been documented internationally. In Australia, several ports have been invaded by pest organisms from international waters, often to the detriment of local species and biodiversity. Blooms of exotic toxic dinoflagellates have also caused significant economic and health impacts in the shellfish and aquaculture industries. The impacts of such introductions are difficult or impossible to reverse.
Port of Brisbane
As part of this national strategy, the Port of Brisbane was surveyed in April 2000 for the presence of introduced marine species and to establish baseline information on biota. Sampling and field work was undertaken at thirty sites in and around the mouth of the Brisbane River. These sites in the port are marked on the map below. In addition, samples were collected from the mouth of Cabbage Tree Creek (Shorncliffe), Pine River (Bramble Bay), the Coffee Pots (channel marker in Moreton Bay) and Gardens Point (Brisbane River).
Selection of sites
In order to increase the likelihood of detecting introduced species, sampling was concentrated at berths with high traffic and high volumes of ballast water discharge. In addition, sampling also included sites adjacent to heavily used berths, tug docks, slipways and a dry dock. Two coastal and one bay site were sampled to determine the spread of any species found to be introduced to the port.
Sampling methods
The methods used to locate introduced species included collecting all organisms from a 1m quadrat on wharf pylons, taking mud samples and germinating dinoflagellate cysts, towing nets to sample plankton, taking large "grab" samples of mud to look for polychaetes (worms) and molluscs (shells) as well as other organisms and visual searches for introduced species by divers. Samples were divided into three groups, for identification by experts at The University of Queensland, the Queensland Museum and the Museum of the Northern Territory.
The Australian Ballast Water Management Advisory Committee (ABWMAC) and the Centre for Research into Introduced Marine Pests (CRIMP) have developed a list of "target species" that are well known pests in Australia and are commonly carried in ballast water. None of the species has been isolated from samples collected in the present study of the Port of Brisbane. There are historical records of introduced species in Moreton Bay. However, none of these has been identified as a potential pest species.
Risk of future introductions
The port has a wide salinity and temperature range and high turbidity. Hilliard and Raaymakers (1997) suggested that these physical extremes would only permit settlement of hardy species. Fortunately for Queensland, most of the pest species introduced to Australia favour cooler waters.
The risk of introductions via ballast water can be reduced only through effective ballast water treatment. At present, the only feasible form of treatment is mid-ocean exchange of ballast during the ship's voyage, although other forms of treatment are currently being investigated. The cost of this method could be greatly reduced if ships carrying ballast water that poses little risk to a receiving port were freed from the need to exchange ballast. This aim will be achieved by the national DSS which will rate the risk of ballast water based on the physical parameters of the receiving port and last port of call. This port baseline survey is an integral part of such a system.
References
Hilliard, R.W. and Raaymakers, S (1997) Ballast Water Risk Assessment: 12 Queensland Ports, Stage 5 Report; Executive Summary and Synthesis of Stages 1-4. EcoPorts Monograph Series No. 14.
Last updated: 28 November 2003