No abstract

We review the status of marine shellfish ecosystems formed primarily by bivalves in Australia, including: identifying ecosystem-forming species, assessing their historical and current extent, causes for decline and past and present management. Fourteen species of bivalves were identified as developing complex, three-dimensional reef or bed ecosystems in intertidal and subtidal areas across tropical, subtropical and temperate Australia. A dramatic decline in the extent and condition of Australia’s two most common shellfish ecosystems, developed by Saccostrea glomerata and Ostrea angasi oysters, occurred during the mid-1800s to early 1900s in concurrence with extensive harvesting for food and lime production, ecosystem modification, disease outbreaks and a decline in water quality. Out of 118 historical locations containing O. angasi-developed ecosystems, only one location still contains the ecosystem whilst only six locations are known to still contain S. glomerata-developed ecosystems out of 60 historical locations. Ecosystems developed by the introduced oyster Crasostrea gigas are likely to be increasing in extent, whilst data on the remaining 11 ecosystem-forming species are limited, preventing a detailed assessment of their current ecosystem-forming status. Our analysis identifies that current knowledge on extent, physical characteristics, biodiversity and ecosystem services of Australian shellfish ecosystems is extremely limited. Despite the limited information on shellfish ecosystems, a number of restoration projects have recently been initiated across Australia and we propose a number of existing government policies and conservation mechanisms, if enacted, would readily serve to support the future conservation and recovery of Australia’s shellfish ecosystems.

Marine aquaculture is growing quickly and has substantial effects on people and the environment. Existing research has demonstrated that marine aquaculture can contribute to ecosystem service provisioning that extends beyond production of a resource; however, the extent and significance of these goods and services are not well understood. Here we review existing knowledge of ecosystem service provision by marine aquaculture by systematically examining 129 peer reviewed papers that describe the provision of nine distinct ecosystem services by operational or experimental marine aquaculture farms. We quantify service provision and classify services by type and by farm characteristics. We show that while certain services, such as nutrient absorption by kelp aquaculture, are well understood and have been documented across multiple species, scales and environments, the evidence for other services, such as the cultural service of tourism, is currently minimal. Importantly, we identify ecosystem services associated with a diversity of farm types (including fish, bivalve, algae and polyculture farms) but find that certain services were most often delivered by specific farm types (e.g. habitat services were most often associated with fish farms). Incorporating acknowledgement of ecosystem services into farm design and planning has the potential to improve environmental performance and sustainable management of aquaculture. However, outstanding questions, including how spatial expansion of marine aquaculture will affect the provisioning of these services, are important challenges facing sustainable development.

No abstract