Indigenous management of sea country |
Black-striped mussel | Crown-of-thorns starfish
Many human activities negatively impact on the coastline and
marine environment including coral reefs and estuaries. Pressures
can arise from local land-based pollution, poor drainage and
effluent management, or can result from land disturbance in
catchments many hundreds of kilometres away. Some of the issues
that need to be addressed in the tropical savannas region
- An increase in sediment and nutrient run-off into rivers.
- Developments in the coastal zone including agriculture,
building of marinas and expanding industry and housing.
- Loss of inshore habitat such as mangroves and saltmarshes from
clearing and development.
- Effects of tourism and destruction of areas of social and
cultural importance, and
- The effects of trawling, overfishing and dieback of
Other activities related to fisheries and aquaculture, shipping
and port industries, and marine tourism and recreation, are all
potentially threatening to the health of the savannas’
coastal and marine environments.
Luckily the pressures and problems of urban sprawl, high
population density and pollution of rivers and lakes are currently
not as extensive in the tropical savannas as they are in other
areas of Australia.
However there are some threats which look to impact the tropical
savannas coastline considerably. These include the impacts of
future sea level rise due to global warming and the changes to
coastal ecosystems as they become inundated with salt water.
Increases in ocean temperature will also change the way coastal
- Aboriginal and Torres Strait Islander fishing rights and lack
of involvement in management.
- Protection and preservation of sites of cultural significance,
in particular Aboriginal and Torres Strait Islander sites of
Introduced marine pest such as the black-striped mussel and
crown-of-thorns starfish can potentially devastate marine
biodiversity. This mussel is able reproduce at an alarming rate
creating monocultures in and around marinas and wharves, excluding
other species, fouling the environment and reducing biodiversity.
They are spread when they hitch a ride from infested areas on the
hulls of commercial and recreational boats. There was an outbreak
in several Darwin marinas in 1999, which was successfully
eradicated after large scale chemical treatment.
Over the past 30 years outbreaks of the coral-eating
crown-of-thorns starfish have caused considerable damage to reefs
in the Indo-Pacific region, including parts of the Great Barrier
Reef. The crown-of-thorns starfish is one of only a few animals
which feed on living coral tissue. It gets its name from the dense
covering of long sharp spines covering its upper surface. At low
densities this animal is just another part of the ecology of a
coral reef. However, if the crown-of-thorns starfish population
grows dramatically, it can reach densities at which it eats corals
faster than they can grow and reproduce. Coral cover can be reduced
significantly and result in major disturbance to the whole ecology
of a reef. If the number of adult crown-of-thorns starfish in one
hectare of the reef rises above about 30, coral cover starts to
decline (Great Barrier Marine Park Authority).
Art and craft out of destructive drift nets
ABANDONED lost or discarded the hundreds of fishing nets that find their way to the waters and shores of the Gulf of Carpentaria pose a real hazard to the six species of marine turtle that breed and nest there… [read more...