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Abstract

1. Benthic assemblages in the fjord-like Bathurst Channel estuarine system, south-western Tasmania, vary over
horizontal scales of 1–5km and vertical scales of 1–10 m. Multivariate analysis indicated a total of eight major
assemblages that characterize different sections and depths of the channel.
2. Because tannins in the low-salinity surface water layer block light, foliose algae reach 5m depth in the
marine western region but do not penetrate below 1m in the east. By contrast, sessile invertebrates are most
abundant below 5m depth in the west and below 2m in the east. Deeper assemblages are unlikely to be
continuous with assemblages in deeper waters off the Tasmanian coast as they are highly constrained by depth
within particular sections of the estuary.
3. While the species composition of the Bathurst Channel biota is most similar to that found elsewhere in
Tasmania, the structural character of the biota in terms of major taxonomic groups is more closely allied to that
found in fjords of south-western Chile and south-western New Zealand. These three regions all possess wilderness
settings, high rainfall that is channelled through estuaries as a low-salinity surface layer, deep-water emergence of
fauna, rapid change in biotic communities over short horizontal and vertical distances, and high levels of local
endemism. They also include some of the most threatened aquatic ecosystems on earth due to increasing human
activity from a near pristine base, and the potentially catastrophic impacts of climate change.

Item Type:	Article
Authors/Creators:	Barrett, NS and Edgar, GJ
Keywords:	climate change;endemism;estuary;macroalgae;marine protected area;sessile invertebrates;threatened habitats
Journal or Publication Title:	Aquatic Conservation: Marine and Freshwater Ecosystems
ISSN:	1099-0755
DOI / ID Number:	https://doi.org/10.1002/aqc.1085
Additional Information:	The definitive published version is available online at: http://interscience.wiley.com
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