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Abstract

1. Port Davey and associated Bathurst Harbour in south-western Tasmania represent one of the world’s most
anomalous estuarine systems owing to an unusual combination of environmental factors. These include: (i) large
uninhabited catchment protected as a National Park; (ii) ria geomorphology but with fjord characteristics that
include a shallow entrance and deep 12-km long channel connecting an almost land-locked harbour to the sea;
(iii) high rainfall and riverine input that generate strongly-stratified estuarine conditions, with a low-salinity
surface layer and marine bottom water; (iv) a deeply tannin-stained surface layer that blocks light penetration to
depth; (v) very low levels of nutrients and low aquatic productivity; (vi) weak tidal influences; (vii) marine bottom
water with stable temperature throughout the year; (viii) numerous endemic species; (ix) strongly depth-stratified
benthic assemblages exhibiting high compositional variability over small spatial scales; (x) deepsea species present
at anomalously shallow depths; (xi) no conspicuous introduced taxa; (xii) a predominance of fragile sessile
invertebrates, including slow-growing fenestrate bryozoans; and (xiii) sponge spicule- and bryozoan-based
sediments that are more characteristic of deep sea and polar environments than those inshore.
2. Although this region has historically been protected by its isolation, seven major anthropogenic stressors
now threaten its natural integrity: boating, fishing, dive tourism, nutrient enrichment, introduced species, onshore
development, and global climate change. These threats are not randomly distributed but disproportionately affect
particular habitat types.
3. For management of environmental risk, the Port Davey–Bathurst Harbour region is subdivided into six
biophysical zones, each with different ecological characteristics, values, and types and levels of potential threat.
In response to the various threats, the Tasmanian Government has enacted an adaptive management regime that
includes a multi-zoned marine protected area and the largest ‘no-take’ estuarine protected area in Australia.
Copyright r 2009 John Wiley & Sons, Ltd.

Item Type:	Article
Authors/Creators:	Barrett, NS and Edgar, GJ and Last, PR
Keywords:	benthic invertebrates; climate change; diver impacts; fishes; introduced marine pests; World Heritage Area
Journal or Publication Title:	Aquatic Conservation: Marine and Freshwater Ecosystems
ISSN:	1099-0755
DOI / ID Number:	10.1002/aqc.1079
Additional Information:	The definitive published version is available online at: http://interscience.wiley.com
Item Statistics:	View statistics for this item

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