2016 SoE Marine Chapter - State and Trends - Seabed, slope (250 m - 700 m)

The Marine chapter of the 2016 State of the Environment (SoE) report incorporates multiple expert templates developed from streams of marine data. This metadata record describes the Expert Assessment "The state and trends of quality of habitats and communities – seabed, slope (250 m - 700 m)". The full Expert Assessment, including figures and tables (where provided), is attached to this record. Where available, the Data Stream(s) used to generate this Expert Assessment are accessible through the "On-line Resources" section of this record.

DESCRIPTION OF HABITAT/COMMUNITY FOR EXPERT ASSESSMENT
This specified depth range (250 m to 700 m) defines the upper continental slope. This habitat is mostly an extremely narrow and typically steep ribbon of seabed beyond the shelf-break, but wider in places (GBR/Coral Sea and North-west Regions). Where it is narrowest and steepest in the Temperate East and South-east Regions, it is typified by sediment draped slopes interspersed with deep reefs, canyons and pinnacles (small seamounts); the latter two habitats are assessed separately. Considering its planar area, this habitat supports disproportionately highly productive fisheries and is therefore subject to high levels of pressure, particularly in the South-east and parts of the Temperate East, but less so in other regions.
Nearly 20% of the 200-700 m depth zone has been mapped with multibeam sonar (MBS) resulting in detailed bathymetry and acoustic backscatter maps of the seabed that enable the identification of deep reefs (Kloser &amp; Keith 2013). The largest proportional coverage is in the southern regions, 75% in the South-east Region, and 36% in the South-west; coverage of the northern regions is &lt;10%.  Deep reefs are particularly abundant and most expansive in area off Australia’s eastern continental margin and in the north-west region (Kloser et al. in press). 
The upper slope harbours a highly diverse benthic fauna (Schlacher et al. 2007, Williams et al. 2010, McEnnulty et al. 2011, Dunstan et al. 2012, McCallum et al. 2013). Off Australia’s west-coast (South-west Region), the upper slope is predominantly sediment-draped with soft coral and sponge dominated communities on the relatively few, small deep reefs (Althaus et al. 2012). In the South-east Region bryozoan communities (assessed separately) dominate the shallower, softer part of the slope (Williams et al. 2009) whereas deep reefs harbour sponge gardens, corals and crinoids. The narrow ribbon of upper slope is the core habitat to many demersal fish species including many commercially targeted species, as well as threatened or management dependent species such as many deepwater sharks including gulper sharks (Centrophorus spp.) (Williams et al. 2012).  There is little specific knowledge of upper slope habitats and biota in other regions. 
DATA STREAM(S) USED IN EXPERT ASSESSMENT
This assessment is based on data derived from Marine National Facility Surveys described in MarLIN (http://www.marine.csiro.au/marlin/search.html) and accessible through the CSIRO Data trawler (http://www.cmar.csiro.au/data/trawler/) and the Atlas of Living Australia (ALA - http://www.ala.org.au/). Many of these data have contributed to data sets compiled under the CERF and NERP Marine Biodiveristy Hubs. Links to specific CSIRO data sets are provided in the "On-line resources" section of this record, ALA datasets not specified.
• Voyage of Discovery north-west (SS05/2007)
• Voyage of Discovery south-west (SS07/2005 &amp; SS10/2005)
• Habitat Mapping (SS01/2000, SS04/2004)
• Habitat and population assessment of giant crabs (2003 - 2005)
• Tasmanian seamounts surveys (SS02/2006 &amp; SS02/2007)

2016 SOE ASSESSMENT SUMMARY [see attached Expert Assessment for full details]
• 2016 •
Assessment grade: Good-Poor
Assessment trend: Improving
Confidence grade: Limited evidence or limited consensus
Confidence trend: Limited evidence or limited consensus
Comparability: Grade and trend are somewhat comparable to the 2011 assessment
• 2011 •
Assessment grade: Very good
Assessment trend: Stable
Confidence grade: Limited evidence or limited consensus
Confidence trend: Limited evidence or limited consensus

CHANGES SINCE 2011 SOE ASSESSMENT
New information on national trawl footprints and a recent assessment of South-east region habitats, which suggests that the South-east region may not have been as widely or as substantially impacted as previously considered and is now expected to be improving albeit slowly.

Tags: benthic habitat, continental slope, expert assessment, seabed, seafloor
Organization: Australian Ocean Data Network