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Abstract

An excursion to the Port Davey Estuarine System in April 1993 confIrmed earlier evidence
of distinct horizontal and vertical zonation patterns within the invertebrate communities of
Bathurst Channel. The fauna, with its dominance of deepwater species, is unique in both
community structure and composition within the entire coastal zone of Australia The
restriction of plant communities to near the surface, reflected by the low light penetration
from dark tannin stained water, is an atypical situation within temperate Australian waters.
The benthic invertebrate fauna is dominated t.y filter feeders such as corals, bryozoans,
tube worms, ascidians and sponges. Marine groups, which are often dominant elsewhere
in the sea, such as molluscs, crustaceans, and echinoderms, are relatively depauperate.
The taxonomy of much of the fauna is still being resolved but initial indications are that it
contains rare species, some of which may be endemic.

The communities contain many sedentary benthic species that are delicate and fragile.
Many of these (eg bryozoans, corals, sea pens) are vulnerable to mechanical damage from
divers or by nets and anchors. They also contain species that are not widely represented in
adjacent inshore habitats and may be 'self-seeding' within the estuary. Many deepwater
animals are habitat specifIc and may be vulnerable to environmental changes caused by
pollutants, nutrient enrichment and other water quality factors. Gaining an understanding
of water flow within the estuary is critical to evaluating the effects of such changes.
This study was little more than a pilot survey and generates more questions than it
answers. The Channel harbours an extremely important but potentially vulnerable fauna
which needs to be given high research and conservation priorities. While the basic
structure of its communities have been identified, more subtle but yet undefined
partitioning of zones appears to be evident. Resolution of these infrastructural elements
awaits further collecting and identification of the spatial patterns. Future research should
attempt to delimit potentially vulnerable communities and their distributions, and identify
less vulnerable sites where ecotourism and other man-related activities could be permitted
without causing environmental damage.

Item Type:	Report (Technical Report)
Authors/Creators:	Edgar, GJ and Last, PR
Journal or Publication Title:	Wilderness Ecosystems Baseline Studies Interim Report 1994:
Publisher:	CSIRO
Item Statistics:	View statistics for this item

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