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An environmental assessment of a proposed amendment to the marine farming zone at Zuidpool Rock in the D’Entrecasteaux Channel (Assessment 2)
reportposted on 2023-05-25, 03:25 authored by Vanessa LucieerVanessa Lucieer, Andrew PenderAndrew Pender
An environmental assessment of a proposed marine farming zone extension at Zuidpool Rock, in the D’Entrecasteaux Channel, was conducted in February 2014. This assessment is comprised of two parts, encompassing Zuidpool Rock northern and southern sites and have been distinguished as Assessments 1 and 2, with the results being presented in two separate reports. This report addresses Assessment 2. Two sites were surveyed in this assessment. The northern site covered 2.51 km2 (251 ha) and the southern site covered 2.81 km2 (281 ha). Both sites were orientated in a north westerly direction. The benthic habitats within the zone assessment area for the northern site comprised of silt (73.6%) and silty sand (26.4%) and the southern site, silt 69.8% and silty sand (30.2%).
Environmental data on substrate type, habitat distribution, bathymetry, and benthic flora and fauna were assessed. Within the northern proposed zone the substrate was characterized by silt and silty sand. The bathymetry ranged from 24 m to 39 m and was characterized by a deep channel to 54 m in the south west of the site which was flanked by two shallower banks, indicative of a drowned river valley. The southern proposed site was characterized by silty sand and sand and a depth strata ranging from 26 m on the southern end of the site with the deepest point found at the bottom of a steep embankment at 46 m.
The Northern Zuidpool site was characterized brown silt on the surface with some evidence of layering to grey silt. All of the New Zealand screwshells (Maoriculpus roseus) that were sampled in the Northern site were dead. Amphipods and squat lobsters (Munida haswelli) were common across the region. Brittle stars (Amphiura elandiformis), polychaetes and squat lobsters (Munida haswelli) were noted in all of the grab samples. Heart urchins (Echinocardium cordatum) and Ghost shrimp (Family: Callianassidae) were also noted.
The Southern Zuidpool site was characterised by brown silt and yellow silty sand substrate with shell grit, evidence of active bioturbation; live and dead New Zealand screwshells (Maoriculpus roseus), brittle stars, squat lobsters (Munida haswelli) and polychaete worms were common across the whole site.
Both of the sites, North and South contained sediment ‘pock mark’ features; these seabed features are common in many parts of the channel. The pock marks that appear in the center of the Zuidpool North site and to the northern part of the Zuidpool South site are identical and are around 20 m in diameter and 1- 2 m deep.
Commissioning bodyInstitute for Marine and Antarctic Studies, University of Tasmania
Department/SchoolInstitute for Marine and Antarctic Studies
PublisherInstitute for Marine and Antarctic Studies, University of Tasmania
Place of publicationHobart, TAS