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News Article
Site: http://phys.org/biology-news/

Together CSIRO, the Western Australian Marine Science Institution (WAMSI), and four Kimberley Aboriginal organisations recently took to the skies to conduct aerial surveys of dugongs—a shy marine mammal that is said to have sparked the legend of mermaids. The information gleaned from the surveys will provide will provide a baseline from which they can create management strategies to help conserve dugongs in the future, according to CSIRO oceans and atmosphere researcher Peter Bayliss. The Kimberley dugong population is both environmentally and culturally important, Mr Bayliss says. "They are considered a keystone species ecologically and are also culturally significant to Aboriginal coastal communities, providing a valuable food source," Mr Bayliss says. "There is a deep cultural knowledge of dugongs in the Kimberley and this will be combined with scientific knowledge for their future management. Dugongs are listed globally as 'vulnerable to extinction' and northern Australia and Torres Strait are thought to be home to the largest remaining healthy populations in the world. However, until now the Kimberley was one of the few areas that had not been subject to scientific survey. Aboriginal rangers from the Balanggarra, Wunambal Gaambera, Dambimangari and Bardi Jawi Native Title groups learnt the techniques of aerial surveying as part of a three-day accredited training course. They then put these skills into practice by boarding a Gippsland G8 Airvan to survey dugongs by flying east-west transect lines over about 30,000 square kilometres of coastal waters—an area nearly half the size of Tasmania. The survey plane flew at a constant height and speed to obtain consistent counts—152m above the water and 185 kilometres per hour—with participants counting dugongs sighted within a 200m strip on each side of the aircraft. They flew 14,000 kilometres during the 18-day survey. The aerial surveying course and surveys are part of the WAMSI Kimberley Marine Science Program's Dugong Management project being run through the Coastal Program of the CSIRO Oceans and Atmosphere Flagship. Explore further: New book inspires children to protect dugongs


Nash K.L.,James Cook University | Graham N.A.J.,James Cook University | Wilson S.K.,Marine Science Program | Wilson S.K.,University of Western Australia | Bellwood D.R.,James Cook University
Ecosystems | Year: 2013

Despite a large number of studies focusing on the complexity of coral reef habitats and the characteristics of associated fish assemblages, the relationship between reef structure and fish assemblages remains unclear. The textural discontinuity hypothesis, which proposes that multi-modal body size distributions of organisms are driven by discontinuous habitat structure, provides a theoretical basis that may explain the influence of habitat availability on associated organisms. In this study we use fractal techniques to characterize patterns of cross-scale habitat complexity, and examine how this relates to body-depth abundance distributions of associated fish assemblages over corresponding spatial scales. Our study demonstrates that: (1) Reefs formed from different underlying substrata exhibit distinct patterns of cross-scale habitat complexity; (2) The availability of potential refuges at different scales correlates with patterns in fish body depth distributions, but habitat structure is more strongly related to the relative abundance of fish in the body depth modes, rather than to the number of modes; (3) As reefs change from coral- to algal-dominated states, the complexity of the underlying reef substratum may change, presenting a more homogenous environment to associated assemblages; (4) Individual fish body depth distributions may be multi-modal, however, these distributions are not static characteristics of the fish assemblage and may change to uni-modal forms in response to changing habitat condition. In light of predicted anthropogenic changes, there is a clear need to improve our understanding of the scale of ecological relationships to anticipate future changes and vulnerabilities. © 2012 Springer Science+Business Media New York. Source


Cole A.J.,James Cook University | Lawton R.J.,James Cook University | Pratchett M.S.,James Cook University | Wilson S.K.,Marine Science Program
Coral Reefs | Year: 2011

Interactions between predators and prey organisms are of fundamental importance to ecological communities. While the ecological impact that grazing predators can have in terrestrial and temperate marine systems are well established, the importance of coral grazers on tropical reefs has rarely been considered. In this study, we estimate the biomass of coral tissue consumed by four prominent species of corallivorous butterflyfishes. Sub-adult butterflyfishes (60-70 mm, 6-11 g) remove between 0.6 and 0.9 g of live coral tissue per day, while larger adults (>110 mm, ~40-50 g) remove between 1.5 and 3 g of coral tissue each day. These individual consumption rates correspond to the population of coral-feeding butterflyfishes at three exposed reef crest habitats at Lizard Island, Great Barrier Reef, consuming between 14.6 g (±2.0) and 19.6 g (±3.9).200 m-2 day-1 of coral tissue. When standardised to the biomass of butterflyfishes present, a combined reefwide removal rate of 4.2 g (±1.2) of coral tissue is consumed per 200 m-2 kg-1 of coral-feeding butterflyfishes. The quantity of coral tissue removed by these predators is considerably larger than previously expected and indicates that coral grazers are likely to play an important role in the transfer of energy fixed by corals to higher consumers. Chronic coral consumption by butterflyfishes is expected to exact a large energetic cost upon prey corals and contribute to an increased rate of coral loss on reefs already threatened by anthropogenic pressure and ongoing climate change. © 2010 Springer-Verlag. Source


Wilson S.K.,Marine Science Program | Wilson S.K.,University of Western Australia | Graham N.A.J.,James Cook University | Fisher R.,Australian Institute of Marine Science | And 6 more authors.
Conservation Biology | Year: 2012

Disturbance plays an important role in structuring marine ecosystems, and there is a need to understand how conservation practices, such as the designation of Marine Protected Areas (MPAs), facilitate postdisturbance recovery. We evaluated the association of MPAs, herbivorous fish biomass, substrate type, postdisturbance coral cover, and change in macroalgal cover with coral recovery on the fringing reefs of the inner Seychelle islands, where coral mortality after a 1998 bleaching event was extensive. We visually estimated benthic cover and fish biomass at 9 sites in MPAs where fishing is banned and at 12 sites where fishing is permitted in 1994, 2005, 2008, and 2011. We used analysis of variance to examine spatial and temporal variations in coral cover and generalized additive models to identify relations between coral recovery and the aforementioned factors that may promote recovery. Coral recovery occurred on all substrate types, but it was highly variable among sites and times. Between 2005 and 2011 the increase in coral cover averaged 1%/year across 21 sites, and the maximum increase was 4%/year. However, mean coral cover across the study area (14%) remained at half of 1994 levels (28%). Sites within MPAs had faster rates of coral recovery than sites in fished areas only where cover of macroalgae was low and had not increased over time. In MPAs where macroalgae cover expanded since 1998 there was no recovery. Where coral was recovering on granite reefs there was a shift in relative prevalence of colony life-form from branching to encrusting species. This simplification of reef structure may affect associated reef fauna even if predisturbance levels of coral cover are attained. ©2012 Society for Conservation Biology. Source


Madin E.M.P.,University of Technology, Sydney | Ban N.C.,James Cook University | Doubleday Z.A.,University of Tasmania | Doubleday Z.A.,University of Adelaide | And 4 more authors.
Global Environmental Change | Year: 2012

Climate change is leading to a redistribution of marine species, altering ecosystem dynamics as species extend or shift their geographic ranges polewards with warming waters. In marine systems, range shifts have been observed in a wide diversity of species and ecosystems and are predicted to become more prevalent as environmental conditions continue to change. Large-scale shifts in the ranges of marine species will likely have dramatic socio-economic and management implications. Australia provides a unique setting in which to examine the range of consequences of climate-induced range shifts because it encompasses a diverse range of ecosystems, spanning tropical to temperate systems, within a single nation and is home to global sea surface temperature change 'hotspots' (where range shifts are particularly likely to occur). We draw on global examples with a particular emphasis on Australian cases to evaluate these consequences. We show that in Australia, range shifts span a variety of ecosystem types, trophic levels, and perceived outcomes (i.e., negative versus positive). The effect(s) of range shifts on socio-economic change variables are rarely reviewed, yet have the potential to have positive and/or negative effects on economic activities, human health and ecosystem services. Even less information exists about potential management responses to range-shifting species. However, synthesis of these diverse examples provides some initial guidance for selecting effective adaptive response strategies and management tools in the face of continuing climate-mediated range shifts. © 2011 Elsevier Ltd. Source

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