James Cook University

About: James Cook University is a education organization based out in Townsville, Queensland, Australia. It is known for research contribution in the topics: Population & Coral reef. The organization has 9101 authors who have published 27750 publications receiving 1032608 citations. The organization is also known as: JCU.

The Geomorphology of the Great Barrier Reef: Development, Diversity and Change

Abstract: Over the last 25 years considerable information on the geomorphological evolution of the world's largest coral reef system, the Great Barrier Reef, has become available. This book reviews the history of geomorphological studies of the Great Barrier Reef and assesses the influences of sea-level change and oceanographic processes on the development of reefs over the last 10,000 years. It presents analyses of recently attained data from the Great Barrier Reef and reconstructions of the sequence of events which have led to its current geomorphology. The authors emphasise the importance of the geomorphological time span and its applications for present management applications. This is a valuable reference for academic researchers in geomorphology and oceanography, and will also appeal to graduate students in related fields.

Disturbance, habitat structure, and the dynamics of a coral-reef fish community

Abstract: Coral reef fishes occupy habitats that are patchy and subject to frequent natural disturbances. Although different types of disturbance are likely to generate different community responses, the relationship between different disturbance agents and their effects on reef fish communities has not been examined experimentally. We studied a set of natural patch reefs, dominated by a diverse array of soft and hard coral cover, at Lizard Island on the Great Barrier Reef (northeastern Australia). The fish assemblages on the reefs were sampled over 4 mo to establish baseline values and then experimentally disturbed. Two types of disturbance were carried out in a factorial combination: pulsed mortality by removing all fish from reefs and pulsed habitat disturbance. Habitat disturbance was applied at two levels: Level 1 consisted only of damaging all live hard corals with a hammer; Level 2 consisted of damaging all live hard corals, and in addition, using a hammer to reduce the height and complexity of the reef matrix. We then monitored the experiment for a further 19 mo, including two recruitment seasons. Unmanipulated control assemblages persisted through time, and despite large changes in total abundance, species composition remained consistent relative to disturbed treatments. Assemblages disturbed by fish removal were resilient, with recolonization from both immigration and larval settlement effectively removing differences between removal treatments and controls 3 mo after manipulation. Habitat disturbance alone generated differences between experimental and control assemblages, which persisted for the duration of the experiment. The more extreme level of habitat disturbance generated more extreme changes in fish assemblages when no pulsed mortality occurred. Habitat disturbance in combination with pulsed mortality generated similar community responses as the habitat disturbance treatment alone. However, fish removal had the effect of eliminating the difference between fish assemblages on reefs subjected to different levels of habitat disturbance. Community response to habitat disturbance was driven by species-specific patterns of reduced abundance of species associated with live coral in combination with increased numbers of those associated with rubble. Declines in the abundance of coral associates on damaged reefs were abrupt, with no recovery observed for the duration of the experiment. In contrast, increases in the abundance of rubble associates were more ephemeral, in that initial high levels of recruitment and immigration were followed by a high rate of loss. Habitat disturbance also generated reefs that typically supported lower fish abundance, fewer species, and increased evenness relative to controls. Our results support a model of patch-reef fish assemblages organized by a combination of deterministic factors (such as habitat structure) and stochastic processes (such as recruitment). These disparate mechanisms operate in concert to generate reasonably consistent patterns of community structure. Habitat structure appears to mediate much of the apparent determinism and is likely to operate both as a reflection of species-specific habitat preferences and by modifying interactions among fish species. Consequently, disturbance plays a substantial role in structuring communities of coral-reef fishes by modifying both spatial and temporal heterogeneity.

Above-ground biomass and structure of 260 African tropical forests.

Abstract: We report above-ground biomass (AGB), basal area, stem density and wood mass density estimates from 260 sample plots (mean size: 1.2 ha) in intact closed-canopy tropical forests across 12 African countries. Mean AGB is 395.7 Mg dry mass ha−1 (95% CI: 14.3), substantially higher than Amazonian values, with the Congo Basin and contiguous forest region attaining AGB values (429 Mg ha−1) similar to those of Bornean forests, and significantly greater than East or West African forests. AGB therefore appears generally higher in palaeo- compared with neotropical forests. However, mean stem density is low (426 ± 11 stems ha−1 greater than or equal to 100 mm diameter) compared with both Amazonian and Bornean forests (cf. approx. 600) and is the signature structural feature of African tropical forests. While spatial autocorrelation complicates analyses, AGB shows a positive relationship with rainfall in the driest nine months of the year, and an opposite association with the wettest three months of the year; a negative relationship with temperature; positive relationship with clay-rich soils; and negative relationships with C : N ratio (suggesting a positive soil phosphorus–AGB relationship), and soil fertility computed as the sum of base cations. The results indicate that AGB is mediated by both climate and soils, and suggest that the AGB of African closed-canopy tropical forests may be particularly sensitive to future precipitation and temperature changes.

Ecological consequences of major hydrodynamic disturbances on coral reefs

Abstract: A recent tsunami and an apparent increase in the frequency of severe tropical storms underscore the need to understand and predict the ecological consequences of major hydrodynamic disturbances. Reef corals provide the habitat structure that sustains the high biodiversity of tropical reefs, and thus provide the foundation for the ecosystem goods and services that are critical to many tropical societies. Here we integrate predictions from oceanographic models with engineering theory, to predict the dislodgement of benthic reef corals during hydrodynamic disturbances. This generalizes earlier work, by incorporating colonies of any shape and by explicitly examining the effects of hydrodynamic gradients on coral assemblage structure. A field test shows that this model accurately predicts changes in the mechanical vulnerability of coral colonies, and thus their size and shape, with distance from the reef crest. This work provides a general framework for understanding and predicting the effects of hydrodynamic disturbances on coral reef communities; such disturbances have a major role in determining species zonation and coexistence on coral reefs, and are critical determinants of how coral assemblages will respond to changes in the frequency and intensity of tropical storms associated with a changing climate.

DNA methylation dynamics, metabolic fluxes, gene splicing, and alternative phenotypes in honey bees

Abstract: In honey bees (Apis mellifera), the development of a larva into either a queen or worker depends on differential feeding with royal jelly and involves epigenomic modifications by DNA methyltransferases. To understand the role of DNA methylation in this process we sequenced the larval methylomes in both queens and workers. We show that the number of differentially methylated genes (DMGs) in larval head is significantly increased relative to adult brain (2,399 vs. 560) with more than 80% of DMGs up-methylated in worker larvae. Several highly conserved metabolic and signaling pathways are enriched in methylated genes, underscoring the connection between dietary intake and metabolic flux. This includes genes related to juvenile hormone and insulin, two hormones shown previously to regulate caste determination. We also tie methylation data to expressional profiling and describe a distinct role for one of the DMGs encoding anaplastic lymphoma kinase (ALK), an important regulator of metabolism. We show that alk is not only differentially methylated and alternatively spliced in Apis, but also seems to be regulated by a cis-acting, anti-sense non–protein-coding transcript. The unusually complex regulation of ALK in Apis suggests that this protein could represent a previously unknown node in a process that activates downstream signaling according to a nutritional context. The correlation between methylation and alternative splicing of alk is consistent with the recently described mechanism involving RNA polymerase II pausing. Our study offers insights into diet-controlled development in Apis.