Aquenal Pty Ltd

Kingston, Australia

Aquenal Pty Ltd

Kingston, Australia

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Edgar G.J.,Aquenal Pty Ltd | Edgar G.J.,University of Tasmania | Davey A.,Aquenal Pty Ltd | Kelly G.,New South Wales Marine Parks Authority | And 2 more authors.
Aquatic Conservation: Marine and Freshwater Ecosystems | Year: 2010

1. Quantitative subtidal surveys of fishes, macro-invertebrates and sessile organisms at 33 sites within the Lord Howe Island Marine Park revealed a rich fauna and flora, including 164 fishes, 40 mobile invertebrate taxa, 53 coral and other sessile invertebrate taxa, 32 algal taxa, and two seagrasses. The biota in this newly-zoned marine park was overwhelmingly tropical when species lists were tabulated; however, species with distributions centred on temperate coasts of eastern Australia and New Zealand occurred in disproportionately high densities compared with the tropical species. 2. Lord Howe Island reefs were generally in good condition. Virtually no bleached coral was observed (0.2% of the reef surface; 0.8% of total hard coral cover). Living scleractinian coral comprised the predominant group of organisms growing on reef surfaces, with 25.5% cover overall. Other major taxa observed were brown algae (18.8% cover) and red algae (16.9% cover). 3. Three distinctive community types were identified within the marine park-coral reefs, macroalgal beds and an offshore/open coast community. The distribution of these community types was strongly related to wave exposure, as indicated by an extremely high correlation with the first principal coordinates axis for biotic data (R2=0.80). 4. The close (<3km) proximity of tropical coral and temperate macroalgal community types off Lord Howe Island is highly unusual, with localized patterns of nutrient enrichment suggested as the primary cause. The macroalgal community type is only known from a small area off the south-western coast that is not protected from fishing. This community is considered highly susceptible to threats because of potential impacts of global warming and the possibility of expansion of sea urchin barrens. Coral bleaching and ocean acidification associated with global climate change also threaten the coral reef community, which includes relatively high numbers of endemic and near endemic fish species. Copyright © 2009 John Wiley & Sons, Ltd.


Edgar G.J.,Aquenal Pty Ltd | Edgar G.J.,University of Tasmania | Last P.R.,CSIRO | Barrett N.S.,University of Tasmania | And 3 more authors.
Aquatic Conservation: Marine and Freshwater Ecosystems | Year: 2010

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. © 2009 John Wiley & Sons, Ltd.


Coutts A.D.M.,Cawthron Institute | Coutts A.D.M.,University of Tasmania | Coutts A.D.M.,Aquenal Pty Ltd | Piola R.F.,Cawthron Institute | And 3 more authors.
Biofouling | Year: 2010

This study experimentally determined the effect of different vessel voyage speeds (5, 10 and 18 knots = 2.6, 5.1 and 9.3 ms-1, respectively) and morphological characteristics including growth form (solitary or colonial), profile (erect or encrusting) and structure (soft, hard or flexible) on the survival of a range of common biofouling organisms. A custom built hydrodynamic keel attached to the bottom of a 6 m aluminium powerboat was used to subject prefouled settlement plates for this purpose. Vessel speeds of 5 and 10 knots had little effect on the species richness of biofouling assemblages tested, however richness decreased by 50% following 18 knots treatments. Species percentage cover decreased with increasing speed across all speed treatments and this decrease was most pronounced at 10 and 18 knots, with cover reduced by 24 and 85% respectively. Survival was greatest for organisms with colonial, encrusting, hard and/or flexible morphological characteristics, and this effect increased with increasing speed. This study suggests that there is predictive power in forecasting future introductions if we can understand the extent to which such traits explain the world-wide distributions of non-indigenous species. Future introductions are a certainty and can only provide an increasing source of new information on which to test the validity of these predications. © 2010 Taylor & Francis.


Edgar G.J.,University of Tasmania | Edgar G.J.,Aquenal Pty Ltd | Davey A.,Aquenal Pty Ltd | Shepherd C.,Australian Department of Primary Industries and Fisheries
Aquaculture | Year: 2010

Analysis of sediment and macrofaunal samples collected during the Tasmanian marine farming finfish monitoring program - a six-year partnership between industry, management and researchers - revealed several univariate indicators to be useful for detecting effects of aquaculture on the benthic environment. Comparisons with reference sites revealed a significant decline in sediment redox potential to at least 4. cm depth at farm sites, and increased proportional abundance of capitellids and decreased bivalve/total mollusc ratio. At compliance sites located 35. m out from lease boundaries, sediment redox potential and faunal assemblage composition were intermediate between patterns found at farm and reference sites. Redox potential at the sediment surface declined on average by 178. eV at reference sites converted to farm sites, with this indicator proving the most sensitive for detecting regional impacts of farming activity.Fish farm effects that extended to regional scales could not be adequately assessed within the project because reference regions without fish farms were not monitored; however, a significant decrease through time at reference and compliance sites in surface redox potential, and increases in sediment organic matter and total macrofaunal abundance, were suggestive that organic enrichment may have extended at low levels across regional scales. Given the implications to biodiversity conservation of region-wide impacts and a need to distinguish fish farm effects from unrelated long-term environmental change, monitoring of reference sites in regions lacking fish farms is urgently needed. © 2010 Elsevier B.V.


Coutts A.D.M.,Aquenal Pty Ltd. | Valentine J.P.,Aquenal Pty Ltd. | Edgar G.J.,Aquenal Pty Ltd. | Edgar G.J.,University of Tasmania | And 2 more authors.
Marine Pollution Bulletin | Year: 2010

Vessels found contaminated with biofouling non-indigenous marine species are predominantly removed from the water and treated in vessel maintenance facilities (i.e., slipways, travel lifts and dry-docks). Using pre-fouled settlement plates to simulate a vessel's removal from the water for treatment, we demonstrate that a range of mobile organisms (including non-indigenous marine species) may be lost to the marine environment as a consequence of this process. We also determined that different levels of biofouling (primary, secondary and tertiary) and emersion durations (0.5, 5 and 15. min) affected the abundance and composition of mobile taxa lost to the marine environment. Primary biofouling plates lost 3.2% of total animals, secondary plates lost 19.8% and tertiary plates lost 8.2%, while hanging duration had only minor effects. The results suggest that removing vessels contaminated with biofouling non-indigenous marine species from the water for treatment may not be as biosecure as is currently recognised. © 2010 Elsevier Ltd.


Valentine J.P.,Aquenal Pty Ltd | Edgar G.J.,Aquenal Pty Ltd | Edgar G.J.,University of Tasmania
Coral Reefs | Year: 2010

Subtidal reef surveys within the Lord Howe Island Marine Park revealed that populations of the sea urchin Tripneustes gratilla underwent an explosive outbreak in some regions of the park over a 2-year period. This urchin was rare or absent during 2006 surveys at 33 sites studied, but at sites off northern Lord Howe Island in 2008, densities averaged >1.3 m-2. Dramatic increases in T. gratilla density (exceeding 4 m-2) were observed at some sites. We quantify community-level impacts of T. gratilla using 'before-after' and 'control-impact' data. Zones closed to fishing exhibited similar increases in T. gratilla density to zones open to fishing. Although not previously reported as a keystone species affecting coral habitat, T. gratilla was found to possess an 'ecosystem engineer' function. Outbreak sites were characterised by significant declines in cover of foliose algae, including red algae, which decreased from 11.2% in 2006 compared to 2.5% in 2008. Brown foliose algae also declined at sites where T. gratilla outbreaks occurred, averaging 20.4% in 2006 compared to 1.8% in 2008. By contrast, crustose coralline algal cover increased at sites where high T. gratilla densities were observed, from 2.7% in 2006 to an average of 42.6% in 2008. We found no clear indication of impacts on sessile invertebrates or flow-on effects to other levels of the food web, with no significant change in coral cover or densities of mobile invertebrates or fish populations associated with the T. gratilla outbreak. © Springer-Verlag 2010.


Ophryotrocha shieldsi, sp. nov. is described from Macquarie Harbour, Tasmania, Australia, where it occurs in high densities beneath the sea cages of fish farms. SCUBA and ROV underwater observations revealed closely spaced mounds of aggregations of the new species. It is closely related to O. lobifera Oug, a species reported from fish farms and whale-falls in the North Sea, from which it can be distinguished by its ovate rather than triangular dorsal lateral lobes, palps with small globular rather than longer digitate palpostyles, and additional jaw differences. © 2010 Magnolia Press.

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