Vertical Distribution and Migration Patterns of Nautilus pompilius

Vertical depth migrations into shallower waters at night by the chambered cephalopod Nautilus were first hypothesized early in the early 20th Century. Subsequent studies have supported the hypothesis that Nautilus spend daytime hours at depth and only ascend to around 200 m at night. Here we challenge this idea of a universal Nautilus behavior. Ultrasonic telemetry techniques were employed to track eleven specimens of Nautilus pompilius for variable times ranging from one to 78 days at Osprey Reef, Coral Sea, Australia. To supplement these observations, six remotely operated vehicle (ROV) dives were conducted at the same location to provide 29 hours of observations from 100 to 800 meter depths which sighted an additional 48 individuals, including five juveniles, all deeper than 489 m. The resulting data suggest virtually continuous, nightly movement between depths of 130 to 700 m, with daytime behavior split between either virtual stasis in the relatively shallow 160–225 m depths or active foraging in depths between 489 to 700 m. The findings also extend the known habitable depth range of Nautilus to 700 m, demonstrate juvenile distribution within the same habitat as adults and document daytime feeding behavior. These data support a hypothesis that, contrary to previously observed diurnal patterns of shallower at night than day, more complex vertical movement patterns may exist in at least this, and perhaps all other Nautilus populations. These are most likely dictated by optimal feeding substrate, avoidance of daytime visual predators, requirements for resting periods at 200 m to regain neutral buoyancy, upper temperature limits of around 25°C and implosion depths of 800 m. The slope, terrain and biological community of the various geographically separated Nautilus populations may provide different permutations and combinations of the above factors resulting in preferred vertical movement strategies most suited for each population

Nautilus at Risk – Estimating Population Size and Demography of Nautilus pompilius

The low fecundity, late maturity, long gestation and long life span of Nautilus suggest that this species is vulnerable to over-exploitation. Demand from the ornamental shell trade has contributed to their rapid decline in localized populations. More data from wild populations are needed to design management plans which ensure Nautilus persistence. We used a variety of techniques including capture-mark-recapture, baited remote underwater video systems, ultrasonic telemetry and remotely operated vehicles to estimate population size, growth rates, distribution and demographic characteristics of an unexploited Nautilus pompilius population at Osprey Reef (Coral Sea, Australia). We estimated a small and dispersed population of between 844 and 4467 individuals (14.6–77.4 km−2) dominated by males (83∶17 male∶female) and comprised of few juveniles (<10%).These results provide the first Nautilid population and density estimates which are essential elements for long-term management of populations via sustainable catch models. Results from baited remote underwater video systems provide confidence for their more widespread use to assess efficiently the size and density of exploited and unexploited Nautilus populations worldwide

Effects of the social environment during adolescence on the development of social behaviour, hormones and morphology in male zebra finches (Taeniopygia guttata)

Abstract Background Individual differences in behaviour are widespread in the animal kingdom and often influenced by the size or composition of the social group during early development. In many vertebrates the effects of social interactions early in life on adult behaviour are mediated by changes in maturation and physiology. Specifically, increases in androgens and glucocorticoids in response to social stimulation seem to play a prominent role in shaping behaviour during development. In addition to the prenatal and early postnatal phase, adolescence has more recently been identified as an important period during which adult behaviour and physiology are shaped by the social environment, which so far has been studied mostly in mammals. We raised zebra finches ( Taeniopygia guttata ) under three environmental conditions differing in social complexity during adolescence\ua0-\ua0juvenile pairs, juvenile groups, and mixed-age groups - and studied males\u2019 behavioural, endocrine, and morphological maturation, and later their adult behaviour. Results As expected, group-housed males exhibited higher frequencies of social interactions. Group housing also enhanced song during adolescence, plumage development, and the frequency and intensity of adult courtship and aggression. Some traits, however, were affected more in juvenile groups and others in mixed-age groups. Furthermore, a testosterone peak during late adolescence was suppressed in groups with adults. In contrast, corticosterone concentrations did not differ between rearing environments. Unexpectedly, adult courtship in a test situation was lowest in pair-reared males and aggression depended upon the treatment of the opponent with highest rates shown by group-reared males towards pair-reared males. This contrasts with previous findings, possibly due to differences in photoperiod and the acoustic environment. Conclusion Our results support the idea that effects of the adolescent social environment on adult behaviour in vertebrates are mediated by changes in social interactions affecting behavioural and morphological maturation. We found no evidence that long-lasting differences in behaviour reflect testosterone or corticosterone levels during adolescence, although differences between juvenile and mixed-age groups suggest that testosterone and song behaviour during late adolescence may be associated

Taphonomy of Crown-of-Thorns Starfish - Implications for Recognizing Ancient Population Outbreaks

A field experiment was conducted to determine whether in situ mass mortality of Acanthaster planci subsequent to a simulated outbreak would leave a recognizable signature in surficial reef sediments. Constituent particle analyses comparing sediments that received starfish carcasses to those that did not revealed that, after a four year interval, the mass mortality was reflected by elevated abundances of starfish ossicles in 1-2 mm and 2-3 mm size classes, but not in > 4 mm and 0.5-1 mm size classes. Additional field study of starfish taphonomy revealed that the abundance of starfish ossicles in surficial sediments decreases through two orders of magnitude between two weeks and four years post-mortem, while tumbling experiments suggest that the size distribution of starfish ossicles is modified by physical processes: the 4 mm class. Taphonomic biasing increased the abundance of crown-of-thorns starfish (COTS) skeletal elements in the 0.5-1 mm size fraction, while the 1-2 mm size and 2-4 mm fractions produced the most reliable signature of starfish mass mortality based on element abundance. Our results demonstrate the importance of taphonomic processes in altering the original size frequency distribution of the COTS skeleton and their potential for biasing predictions of past population levels derived from constituent particle analyses of surficial reef sediments

Building co-management as a process: Problem solving through partnerships in Aboriginal country, Australia

Collaborative problem solving has increasingly become important in the face of the complexities in the management of resources, including protected areas. The strategy undertaken by Girringun Aboriginal Corporation in north tropical Queensland, Australia, for developing co-management demonstrates the potential for a problem solving approach involving sequential initiatives, as an alternative to the more familiar negotiated agreements for co-management. Our longitudinal case study focuses on the development of indigenous ranger units as a strategic mechanism for the involvement of traditional owners in managing their country in collaboration with government and other interested parties. This was followed by Australia's first traditional use of marine resources agreement, and development of a multi-jurisdictional, land to sea, indigenous protected area. In using a relationship building approach to develop regional scale co-management, Girringun has been strengthening its capabilities as collaborator and regional service provider, thus, bringing customary decision-making structures into play to 'care for country'. From this evolving process we have identified the key components of a relationship building strategy, 'the pillars of co-management'. This approach includes learning-by-doing, the building of respect and rapport, sorting out responsibilities, practical engagement, and capacity-building

The Great Barrier Reef and Coral Sea

The Coral Sea lies in the southwestern Pacific Ocean, bordered by Australia, Papua New Guinea, the Solomon Islands, Vanuatu, New Caledonia, and the Tasman Sea. The Great Barrier Reef (GBR) constitutes the western margin of the Coral Sea and supports extensive submerged reef systems in mesophotic depths. The majority of research on the GBR has focused on Scleractinian corals, although other taxa (e.g., fishes) are receiving increasing attention. To date, 192 coral species (44% of the GBR total) are recorded from mesophotic depths, most of which occur shallower than 60 m. East of the Australian continental margin, the Queensland Plateau contains many large, oceanic reefs. Due to their isolated location, Australia's Coral Sea reefs remain poorly studied; however, preliminary investigations have confirmed the presence of mesophotic coral ecosystems, and the clear, oligotrophic waters of the Coral Sea likely support extensive mesophotic reefs. Although mesophotic reefs in the GBR and Coral Sea are among the best-studied globally, most research has focused on only a few sites, and research effort dedicated to mesophotic coral ecosystems remains negligible compared to shallow-water reefs. Despite the lack of ecological data from most mesophotic reef habitats, precautionary management approaches that explicitly considered latitudinal and cross-shelf gradients in the environment resulted in mesophotic reefs being well-represented in no-take areas in the GBR. In contrast, mesophotic reefs in the Coral Sea currently receive little protection