Australia's green economic potential

This Centre for Policy Development briefing paper looks at the issues raised in the Green Economy Report from an Australian perspective and provides a primer to the challenges involved in transforming our economy to operate within environmental limits. It also examines the opportunities of embracing sustainable economic policy solutions in four areas: water, energy, cities and urban transport, and waste management and recycling.

Analysing stakeholder-associated risks in green buildings : a social network analysis method

In the research of risk associated with developing energy and water efficient green buildings, previous studies had mainly focused on "what the risks are and how the risks may impact on project objectives", which were from an inward looking self-perspective and treated the risks in isolation from one another. While intensive research efforts have been dedicated to risk identification, assessment, classification, prioritisation and mitigation, a research gap exists, that is previous studies had ignored the fact that most risks are interrelated and associated with internal or external project stakeholders. To remedy the gap, this current research developed and presented a SNA (Social Network Analysis) based stakeholder-associated risk analysis method to assess risks in green buildings and the interactions between the risks. A case study has been conducted to demonstrate and validate this method. This research contributes to the development of a new theory to model the interdependent and interactive relationships of risks by using SNA as a methodology. This research should broaden project managers' awareness of the influential risks in green building and enhance their ability to perceive, understand, assess, and mitigate the risks in an effective and efficient way, thereby achieving higher performance in strategic risk management and stakeholder communication in green building development.

Evidence from genetic and Lagrangian drifter data for transatlantic transport of small juvenile green turtles

Aim  A key life-history component for many animals is the need for movement between different geographical locations at particular times. Green turtle (Chelonia mydas) hatchlings disperse from their natal location to spend an early pelagic stage in the ocean, followed by a neritic stage where small juveniles settle in coastal areas. In this study, we combined genetic and Lagrangian drifter data to investigate the connectivity between natal and foraging locations. In particular we focus on the evidence for transatlantic transport. Location  Atlantic Ocean.

Methods  We used mitochondrial DNA (mtDNA) sequences (n = 1567) from foraging groups (n = 8) and nesting populations (n = 12) on both sides of the Atlantic. Genetic data were obtained for Cape Verde juvenile turtles, a foraging group not previously sampled for genetic study. Various statistical methods were used to explore spatial genetics and population genetic structure (e.g. exact tests of differentiation, Geneland and analysis of molecular variance). Many-to-many mixed stock analysis estimated the connectivity between nesting and foraging groups.

Results  Our key new finding is robust evidence for connectivity between a nesting population on the South American coast (25% of the Surinam nesting population are estimated to go to Cape Verde) and a foraging group off the coast of West Africa (38% of Cape Verde juveniles are estimated to originate from Surinam), thus extending the results of previous investigations by confirming that there is substantial transatlantic dispersal in both directions. Lagrangian drifter data demonstrated that transport by drift across the Atlantic within a few years is possible.

Main conclusions  Small juvenile green turtles seem capable of dispersing extensively, and can drop out of the pelagic phase on a transatlantic scale (the average distance between natal and foraging locations was 3048 km). Nevertheless, we also find support for the ‘closest-to-home’ hypothesis in that the degree of contribution from a nesting population to a foraging group is correlated with proximity. Larger-sized turtles appear to feed closer to their natal breeding grounds (the average distance was 1133 km), indicating that those that have been initially transported to far-flung foraging grounds may still be able to move nearer to home as they grow larger.

Detecting female precise natal philopatry in green turtles using assignment methods

It is well established that sea turtles return to natal rookeries to mate and lay their eggs, and that individual females are faithful to particular nesting sites within the rookery. Less certain is whether females are precisely returning to their natal beach. Attempts to demonstrate such precise natal philopatry with genetic data have had mixed success. Here we focused on the green turtles of three nesting sites in the Ascension Island rookery, separated by 5–15 km. Our approach differed from previous work in two key areas. First, we used male microsatellite data (five loci) reconstructed from samples collected from their offspring (N = 17) in addition to data for samples taken directly from females (N = 139). Second, we employed assignment methods in addition to the more traditional F-statistics. No significant genetic structure could be demonstrated with FST. However, when average assignment probabilities of females were examined, those for nesting populations in which they were sampled were indeed significantly higher than their probabilities for other populations (Mann–Whitney U-test: P < 0.001). Further evidence was provided by a significant result for the mAIC test (P < 0.001), supporting greater natal philopatry for females compared with males. The results suggest that female natal site fidelity was not sufficient for significant genetic differentiation among the nesting populations within the rookery, but detectable with assignment tests.

The movements and submergence behaviour of male green turtles at Ascension Island

The movements and submergence behaviour of two male green turtles (Chelonia mydas) on their mating grounds at Ascension Island were investigated by satellite telemetry. During the mating season, males tended to conduct much shorter dives (typically <15 min) than those recorded previously for females during the internesting period at this rookery. This suggests that throughout the mating season males maintained relatively high activity levels, presumably associated with locating and mating with as many females as possible to maximise their reproductive output. At the end of their residence at the mating ground, the two males conducted longer dives (48 min and 21 min, respectively), suggesting that they rested before their migration away from the island. Although very few locations were obtained during this migration, those obtained showed that males migrate to South America, as has been shown previously for females from this population.

Movements of migrating green turtles in relation to AVHRR derived sea surface temperature

Previous studies have shown that for some populations of marine turtle, individuals move along narrow migration corridors in the open ocean. It has been suggested that these migration corridors may correspond with nearsurface oceanographic features that can be detected by remote sensing. This idea is examined by superimposing the tracks of green turtles (Chelonia mydas) migrating from Ascension Island to Brazil, on sea surface temperature (SST) data derived from Advanced Very High Resolution Radiometer (AVHRR) images. The turtles did not follow specific isotherms during migration nor make turns en-route where specific thermal cues were encountered. These results suggest that for this population, SST plays a minimal role in influencing the exact route that individuals follow.

Navigation by green turtles: which strategy do displaced adults use to find Ascension Island?

Sea turtles are known to perform long-distance, oceanic migrations between disparate feeding areas and breeding sites, some of them located on isolated oceanic islands. These migrations demonstrate impressive navigational abilities, but the sensory mechanisms used are still largely unknown. Green turtles breeding at Ascension Island perform long oceanic migrations (>2200 km) between foraging areas along the Brazilian coast and the isolated island. By performing displacement experiments of female green turtles tracked by satellite telemetry in the waters around Ascension Island we investigated which strategies most probably are used by the turtles in locating the island. In the present paper we analysed the search trajectories in relation to alternative navigation strategies including the use of global geomagnetic cues, ocean currents, celestial cues and wind. The results suggest that the turtles did not use chemical information transported with ocean currents. Neither did the results indicate that the turtles use true bi-coordinate geomagnetic navigation nor did they use indirect navigation with respect to any of the available magnetic gradients (total field intensity, horizontal field intensity, vertical field intensity, inclination and declination) or celestial cues. The female green turtles successfully locating Ascension Island seemed to use a combination of searching followed by beaconing, since they searched for sensory contact with the island until they reached positions NW and N of the Island and from there presumably used cues transported by wind to locate the island during the final stages of the search.