Seabed exposure and ecological disturbance on Australia's continental shelf: Potential surrogates for marine biodiversity  

Authors / CoAuthors

Hughes, M.G. | Harris, P.T. | Brooke, B.P.

Abstract

Disturbances characterise many natural environments - on land, a forest fire that removes a patch of old-growth trees is an example. The trees that first colonise the vacant patch may be a different species to the surrounding old-growth forest and hence, taken together, the disturbed and undisturbed forest has a higher biodiversity than the original undisturbed forest. This simple example demonstrates the intermediate disturbance hypothesis (IDH) that has applications in many natural environments. The application of IDH is significant for managers tasked with managing and conserving the biodiversity that exists in a given area. In this report we have used models of seabed sediment mobilisation to examine IDH for Australia's continental shelf environment. Although other disturbance processes may occur (eg. biological, temperature, salinity, anthropogenic, etc.) our study addresses only the physical disturbance of the seabed by waves and currents. Our study has shown that it is feasible to model the frequency and magnitude of seabed disturbance in relation to the dominant energy source (wave-dominated shelf, tide-dominated shelf or tropical cyclone dominated shelf). We focussed our attention on high-energy, patch-clearing events defined as exceeding the Shields parameter value of 0.25. Based on what is known about rates of ecological succession for different substrate types (gravel, sand, mud) we derive maps predicting the spatial distribution of a dimensionless ecological disturbance index (ED). Only a small portion of the shelf (perhaps ~10%) is characterised by a disturbance regime as defined here. Within these areas, the recurrence interval of disturbance events is comparable to the rate of ecological succession and meets our defined criteria for a disturbance regime. To our knowledge, this is the first time such an analysis has been attempted for any continental shelf on the earth.

Product Type

document

eCat Id

71210

Contact for the resource

Keywords

• GA PublicationRecord

( Theme )

• continental shelf

( Theme )

• bathymetry

( Theme )

• marine biodiversity

( Theme )

• sedimentology

( Theme )

• seabed

( Theme )

• marine

( Theme )

• CERF

• AU

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

• Published_External

Publication Date

2010-01-01T00:00:00

Creation Date

Security Constraints

Australian Government Security ClassificationSystem    

Classification - unclassified

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Creative Commons Attribution 4.0 International Licence    

Access - license

Use - license

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Purpose

Maintenance Information

unknown

Topic Category

geoscientificInformation

Series Information

Record 2010/043

Lineage

Unknown

Parent Information

Extents

[-44, -7, 110, 156]

Reference System

Spatial Resolution

Service Information

Associations

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