Seagrass loss could be fish disaster
A recently published review of seagrass in Australia's coastal waters calls for action to halt their decline, warning that Australian fisheries may be at stake.
The Seagrass Review and an accompanying plan of action have been released on the eve of the major environmental conference, Coast to Coast 2000, in Melbourne. The published review is a comprehensive examination of the state of Australian seagrasses and their vital role in marine ecosystems.
"If seagrass beds continue to disappear there will be serious economic and ecological consequences," says CSIRO's Dr Alan Butler, co-author of the report.
Australia has more seagrass and more seagrass species, than any other country due to the geological stability of the continent. Dr Butler says the review backs calls for better management of the resource, estimated at around 51,000 square kilometres; a collaborative approach to the issue between managers and users, and establishes priorities for seagrass research in Australia, particularly on the links between the health and productivity of fisheries and seagrasses.
According to the review, despite their name, seagrasses are not grasses at all but highly specialised marine flowering plants adapted to soft sediments of nearshore environments. Although there are less that 70 species globally - of which Australia has more than half - these plants have evolved from several lineages of land plants adapted to a totally submersed life. Seagrasses indirectly support various coastal fisheries largely as a nursery for juevniles.
"The whole community is a stakeholder in seagrass and we have a national opportunity to rebuild a resource that is one link in a critical chain of habitats important to fisheries, aquaculture, tourism and the healthy functioning of nearshore marine ecosystems," says Butler.
Among possible causes of seagrass loss are sewage and industrial-waste dumping, turbidity from dredging and ship movements and damage from natural events like floods and cyclones.
"While we need to understand the changes taking place, we also need to identify activities that seriously impact on seagrasses and how affected seagrass beds can be rehabilitated.
"Although we know a lot about seagrasses, exactly what role they play is still unclear", says Butler. "Seagrasses come in different shapes and forms and most likely have different ecological functions, especially as they relate to fisheries. Some small species, including the favourite foods for dugongs, regenerate quickly, while others are slow-growing and long-lived, and slower to recover from environmental changes".