2016 SoE Marine Chapter - State and Trends - Marine connectivity based on physical processes

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 physical, biogeochemical and biological processes – Marine connectivity based on physical processes". 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 ECOLOGICAL PROCESS FOR EXPERT ASSESSMENT
Marine biological connectivity around Australia is driven by physical processes such as winds, waves, tides and currents, that operate across a wide range of time and space scales. These water movements carry and disperse dissolved substances (nutrients and chemical pollutants) and particulates (sediments, marine debris and planktonic organisms) that are critical to the functioning of marine ecosystems. High connectivity can have positive or negative influences on ecosystem components depending on the circumstances, as can low connectivity (i.e. high retention). For example, transport of eggs and larvae from spawning grounds to nursery areas may be critical to successful breeding, but may also contribute to the spread of harmful species.
Over Australia’s mid- and inner- continental shelves circulation and connectivity patterns tend to be dominated by wind and tidal influences, while the offshore environment is strongly influenced by major currents systems including the poleward flowing Leeuwin Current (LC) in the west and its extension along the southern Australian coast to Tasmania, and the East Australia Current (EAC) in the east. The strength of these currents varies with decadal forcing cycles, such as ENSO, SAM, and IOD, and in some locations there is also evidence of long-term connectivity change consistent with climate change. For example, increased southward flow of the EAC (Ridgway 2007) has been associated with major southward range extensions for almost 100 species (Frusher et al 2014; Sunday et al 2015). This represents a major increase in connectivity between northern and southern biological populations along the eastern seaboard.  In contrast, this southern extension may have reduced connectivity in the south-to-north direction.
DATA STREAM(S) USED IN EXPERT ASSESSMENT
Published papers. CSIRO creates and maintains models used to study dispersal (Bluelink – BRAN product). IMOS holds data on ocean current strength, individual researchers hold data on species of interest. Report Cards have started to explicitly include connectivity as an indicator - http://ghhp.org.au/report-cards/2015/environmental.

2016 SOE ASSESSMENT SUMMARY [see attached Expert Assessment for full details]
• 2016 •
Assessment grade: Poor
Assessment trend: Deteriorating
Confidence grade: Limited evidence or limited consensus
Confidence trend: Limited evidence or limited consensus
Comparability: Grade and trend are not directly comparable to the 2011 assessment
• 2011 • Connectivity – spatial/physical disjunctions
Assessment grade: Very good
Assessment trend: Stable
Confidence grade &amp; trend: Limited evidence or limited consensus
• 2011 • Connectivity – biological, migration, flyways
Assessment grade: Good
Assessment trend: Deteriorating
Confidence grade &amp; trend: Limited evidence or limited consensus
• 2011 • Connectivity – recruitment, settlement
Assessment grade: Good
Assessment trend: Stable
Confidence grade &amp; trend: Limited evidence or limited consensus
• 2011 • Connectivity – genome structures, genetic adaptation
Assessment grade: Good
Assessment trend: Stable
Confidence grade &amp; trend: Limited evidence or limited consensus

CHANGES SINCE 2011 SOE ASSESSMENT
Unclear how the 2011 assessment was done.

Tags: biological connectivity, coastal processes, environmental indicators, expert assessment
Organization: Australian Ocean Data Network