Apart from a growing interest in aquaculture activities in Australia, there is a need to identify the impacts associated with those activities, in order to protect the marine ecosystem. This is a high priority for Australian environmental regulators who are unlikely to allow additional aquaculture activities in the absence of knowledge about possible environmental impacts.

Gaps in our knowledge on the effects of aquaculture impacts on seagrasses and on ways to protect and restore seagrasses were highlighted in a recent review commissioned by FRDC (Butler and Jernakoff 1999). Potential impacts on seagrass meadows include the effects of reduced light and increased nutrient levels. Other issues of importance include the responses of seagrasses to perturbations and the time taken for seagrasses to recover from these impacts. Unless regulators can be confident that shellfish longline aquaculture does not significantly impact areas such as seagrass meadows, it is unlikely that the industry will be able to utilise these potentially suitable areas for expansion and development. Therefore, there is an urgent need to obtain this information and that it has the power to assist environmental regulators in knowing the level of impact, or lack thereof, when making decisions regarding the development of additional aquaculture leases.

Specific needs for the research are formed by the following questions:

- Can mussel farming be conducted over seagrass beds without impact?
- Are the impacts of mussel farming reversible over time if aquaculture activities cease in a particular area (e.g. through site rotation)?
- Is the extent of impact of mussel farming on seagrasses the same throughout the year (i.e. seasonal influences)?
- Are the rates of impact and recovery from potential impact from mussel farming compatible with available adaptive management options?

There is thus a need to undertake research to:

- Provide managers and regulators with appropriate data on the likely consequences of siting mussel leases on or near seagrass communities so they can make informed decisions
- Provide quantitative data on the a) physical changes and b) biological changes to the seagrass habitat as a result of longline mussel aquaculture provide recommendations on management options to minimise seagrass disturbance from longline aquaculturel
- Provide data that allows mussel aquaculture to develop in an orderly and sustainable manner
- Provide a tool for future management decisions on the interaction of aquaculture and seagrass