An application of Gaussian radial based function neural networks for the control of a nonlinear multi link robotic manipulator

The theory of Gaussian radial based function neural networks is developed along with a stable adaptive weight training law founded upon Lyapunov stability theory. This is applied to the control of a nonlinear multi-linked robotic manipulator for the general case of N links. Simulations of a two link system are performed and demonstrate the derived principles

How does a widespread reef coral maintain a population in an isolated environment?

In a changing global environment, previously suboptimal habitats may become climate refuges for species. For instance, the ranges of some tropical reef corals are already expanding poleward. Understanding the demographic strategies by which isolated or marginal populations persist is therefore important, especially since such populations are often both vulnerable to local extinction and sources of evolutionary novelty. This study builds an integral projection model from individual-level demographic rates for a genetically isolated population of a reef coral, Plesiastrea versipora, in Sydney Harbour, Australia, in order to understand the population-level demographic characteristics allowing its persistence. We show that this population is thriving, with the potential to rapidly increase in benthic cover, due to high adult survivorship and at least sporadic high recruitment. Medium-sized colonies are the most important for long-term population viability due to their reproductive potential. Nonetheless, the population's persistence is sensitive to recruitment and growth rates, and protecting it from factors that affect these processes is likely to be crucial for its longer-term survival

The tropicalization of temperate marine ecosystems: Climate-mediated changes in herbivory and community phase shifts

Climate-driven changes in biotic interactions can profoundly alter ecological communities, particularly when they impact foundation species. In marine systems, changes in herbivory and the consequent loss of dominant habitat forming species can result in dramatic community phase shifts, such as from coral to macroalgal dominance when tropical fish herbivory decreases, and from algal forests to 'barrens' when temperate urchin grazing increases. Here, we propose a novel phase-shift away from macroalgal dominance caused by tropical herbivores extending their range into temperate regions. We argue that this phase shift is facilitated by poleward-flowing boundary currents that are creating ocean warming hotspots around the globe, enabling the range expansion of tropical species and increasing their grazing rates in temperate areas. Overgrazing of temperate macroalgae by tropical herbivorous fishes has already occurred in Japan and the Mediterranean. Emerging evidence suggests similar phenomena are occurring in other temperate regions, with increasing occurrence of tropical fishes on temperate reefs. © 2014 The Author(s) Published by the Royal Society. All rights reserved

The Coral Trait Database, a curated database of trait information for coral species from the global oceans (vol 3, 160017, 2016)

This corrects the article DOI: 10.1038/sdata.2016.17

Australian seagrass seascapes: present understanding and future research directions

Seagrass seascapes are 100s m to 1000s of km coastal regions in nearshore, sandy to muddy benthic environments that are characterized by the presence of seagrasses. Here we explore the development of seagrass seascape research in Australia. Determining the distribution of seagrasses started with mapping their extent, but improvements in remote sensing and statistical modelling has allowed us assess the large scale spatial distribution and temporal dynamics of seagrass seascapes. We use a case study from Moreton Bay, near Brisbane, Queensland to demonstrate changes in seagrass meadows over time. Terrestrial landscape indices and their use in seagrass studies is reviewed. Some indices perform better to summarize patch to meadow scale changes in the distribution and structure of seagrasses. A case-study is then presented, comparing landscape indices calculated from observed changes in seagrass patches and meadows to a spatially-explicit model simulation, to explore the drivers for changes in the seagrass seascape's demographic processes, clonal growth and recruitment from seeds. The role of landscape structure in the movement and abundance of associated fauna in seagrass seascapes using landscape approaches is then reviewed. This is followed by a summary outlining directions for future research that combine landscape ecology and remote sensing techniques with population and community biology

The roles of seagrasses in structuring associated fish assemblages and fisheries

Seagrasses are known to provide important habitats for a diversity of fish and fisheries species. Continued research has allowed us to re-evaluate the generalisations, and identify the gaps in our knowledge regarding these habitats, particularly in an Australian context. Seagrasses generally form part of a mosaic with other habitats within a seascape that contributes to its overall biodiversity of fish. Patterns of abundance and diversity of fish between seagrass and other habitats, such as unvegetated flats and reef habitats, is inconsistent and depends on the region, fish and seagrass species, and sampling method. Edge effects, adjacent habitats, and fragmentation can strongly influence fish assemblages. Seagrass structural complexity can enhance survival and growth of juvenile fishes, but recent studies show that survival rates of individual prey do not vary greatly across seagrass densities when densities of both prey and predators increase with seagrass density. The concept of the nursery habitat has been built on data from studies in estuaries or highly seasonal seagrass habitats, whereas recent studies in marine systems or cool temperate seagrass meadows suggest that this role does not always hold. Direct grazing on seagrasses by fishes occurs mainly in tropical regions, although there is a paucity of data on this process along with several other processes, from tropical Australia. Grazing on seagrasses by fishes appears to be limited in temperate regions, with consumption of seagrass restricted mainly to omnivorous species. However, tropicalisation, that is, the immigration of tropical grazers to higher latitudes due to global ocean warming, is predicted to increase grazing rates on temperate seagrasses. Reductions in seagrass biomass caused by increased grazing will disrupt connectivity processes between seagrass meadows and surrounding habitats, and are likely to have significant ramifications for the biodiversity and ecosystem services those other coastal habitats provide. Although other habitats rely on inputs of seagrass detritus, and the immigration of fish and fisheries species from their juvenile seagrass habitats, quantitative data on this link are limited. Evidence that fisheries declines, either directly or indirectly, have resulted from seagrass loss is equivocal to date, and therefore, the quantification of this role is still needed. Managing seagrass for fisheries is complex, and many fisheries agencies embrace ecosystem-based management, but do not have direct responsibility for seagrass habitat. Significant progress has been made in our knowledge of fish and fisheries in seagrasses, but our review highlights significant knowledge gaps where further research is recommended