Bonney coast upwelling

Legal description

The Commonwealth marine area is a matter of national environmental significance under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). As such, actions that have, will have, or are likely to have, a significant impact on it require approval.

In February 2014, the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) became the sole designated assessor of petroleum and greenhouse gas activities in Commonwealth waters in accordance with the Minister for the Environment’s endorsement of NOPSEMA’s environmental authorisation process under Part 10, section 146 of the EPBC Act. Under the streamlined arrangements, impacts on the Commonwealth marine area by petroleum and greenhouse gas activities will be assessed solely through NOPSEMA.

Key ecological features (KEFs) are not matters of national environmental significance and have no legal status in their own right. However, they may be considered as components of the Commonwealth marine area.

This KEF was identified in the South-east Marine Regional Profile. This profile has no legal status in decision-making under the EPBC Act, but it is another source of information which may be considered when relevant.

Values

The Bonney coast upwelling is a predictable, seasonal upwelling bringing cold nutrient rich water to the sea surface and supporting regionally high productivity and high species diversity in an area where such sites are relatively rare and mostly of smaller scale.

It is one of 12 widely recognised and well-known areas worldwide where blue whales are known to feed in relatively high numbers.

The area is significant as one of the largest and most predictable upwellings in south-eastern Australia. This is not the only upwelling in southeast Australia driven by the prevailing south-easterly winds, but it is the most prominent. In addition to whales, many endangered and listed species frequent the area, possibly also relying on the abundance of krill that provide a food source to many seabirds and fish. The high productivity of the Bonney Upwelling is also capitalised on by other higher predator species such as little penguins and Australian fur seals feeding on baitfish.

National and/or regional importance

The Bonney Coast upwelling is defined as a key ecological feature as it is an area of high productivity and aggregations of marine life.

Location

The Bonney coast lies in southeastern Australia between Cape Jaffa, South Australia and Portland, Victoria.

This feature displays seasonal and annual variation. The spatial boundary of this KEF, as defined in the Conservation Values Atlas, was derived through a review of enhanced chlorophyll occurence for summer seasonal data (1998-2010) provided by CSIRO.

Description

The upwelling occurs when strong southeasterly surface winds induce Ekman transport of warm, nutrient-deficient surface waters away from the coastline. This leads to surface upwellings bringing cool, nutrient-rich deep waters closer to the surface where there is enough sunlight for primary production to take place (Hosack & Dambacher 2012). The upwelling season begins slowly in November and December, peaks from January to March, and then declines from April (Nieblas et al. 2009). The Bonney coast upwelling is unique in that it is a persistent seasonal feature due to wind-induced upwelling but with lower mean wind speeds relative to coastal upwelling areas typically found on the eastern margins of the world’s oceans (Nieblas et al. 2009). Similar to other seasonal upwelling systems, Nieblas et al. found that intraseasonal variability follows four distinct phases within the upwelling season of "onset", "sustained", "quiescent" and "downwelling" periods. The phases commence in November/December, January/February, March and April respectively.

Model information

The department and CSIRO conducted collaborative research on KEFs to identify indicators for monitoring marine ecosystem health in the Commonwealth Marine Area. As part of this process, qualitative models were developed for 30 KEFs, including the Bonney coast upwelling. Further information can be found at https://publications.csiro.au/publications/publication/PIcsiro:EP132926.