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 relationship between swimming ability and habitat use in wrasses (Labridae)

Abstract: Habitat use is described for a local assemblage of wrasses (family Labridae) at the among-habitat and microhabitat scales of two fringing reef sites at Lizard Island, northern Great Barrier Reef. Visual censuses were used to determine the distribution and abundance of species in five reef habitat zones, and their relative positions within the water column over the reef flat. Based on previous theoretical and empirical analysis of labrid locomotion, mean pectoral fin aspect-ratio residuals were used as an estimate of swimming performance to examine the relationship between swimming ability and habitat use. Among-habitat distributions of inferred swimming ability displayed a distinct dichotomy between shallow and deep reef habitat zones, suggesting a relationship with wave energy. High wave energy (shallow) habitats were characterised by labrids with high (above 0.2) pectoral fin aspect-ratio residuals (fish that use lift-based swimming and achieve high sustained swimming speeds). Although low (below –0.2) aspect-ratio residual species were only in abundance in low wave energy (deeper) habitats, they were also present in low numbers (<7 individuals/100 m2) on the high wave energy reef flat. Water-column use within the reef flat indicated that these low aspect-ratio residual species display a restricted use of the water column and may use substratum complexity and boundary layer effects as a refuge from high levels of water movement. Overall, locomotor morphology was a good predictor of among-habitat and microhabitat use for wrasses at this location. We propose that locomotor performance may be a general force in shaping habitat use by wrasses over these two spatial scales. Some deviations from these general patterns are discussed with regard to the role of behaviour as a mediating factor between morphology and ecology.

Vulnerability of sea turtle nesting grounds to climate change

Abstract: Given the potential vulnerability of sea turtles to climate change, a growing number of studies are predicting how various climatic processes will affect their nesting grounds. However, these studies are limited by scale, because they predict how a single climatic process will affect sea turtles but processes are likely to occur simultaneously and cause cumulative effects. This study addresses the need for a structured approach to investigate how multiple climatic processes may affect a turtle population. Here, we use a vulnerability assessment framework to assess the cumulative impact of various climatic processes on the nesting grounds used by the northern Great Barrier Reef (nGBR) green turtle population. Further, we manipulate the variables from this framework to allow users to investigate how mitigating different climatic processes individually or simultaneously can influence the vulnerability of the nesting grounds. Our assessment indicates that nesting grounds closer to the equator, such as Bramble Cay and Milman Island, are the most vulnerable to climate change. In the short-term (by 2030), sea level rise will cause the most impact on the nesting grounds used by the nGBR green turtle population. However, in the longer term, by 2070 sand temperatures will reach levels above the upper transient range and the upper thermal threshold and cause relatively more impact on the nGBR green turtle population. Thus, in the long term, a reduction of impacts from sea-level rise may not be sufficient, as rookeries will start to experience high vulnerability values from increased temperature. Thus, in the long term, reducing the threats from increased temperature may provide a greater return in conservation investment than mitigating the impacts from other climatic processes. Indeed, our results indicate that if the impacts from increased temperature are mitigated, the vulnerability values of almost all rookeries will be reduced to low levels.

Putting prey and predator into the CO2 equation – qualitative and quantitative effects of ocean acidification on predator–prey interactions

Abstract: Little is known about the impact of ocean acidification on predator–prey dynamics. Herein, we examined the effect of carbon dioxide (CO2) on both prey and predator by letting one predatory reef fish interact for 24 h with eight small or large juvenile damselfishes from four congeneric species. Both prey and predator were exposed to control or elevated levels of CO2. Mortality rate and predator selectivity were compared across CO2 treatments, prey size and species. Small juveniles of all species sustained greater mortality at high CO2 levels, while large recruits were not affected. For large prey, the pattern of prey selectivity by predators was reversed under elevated CO2. Our results demonstrate both quantitative and qualitative consumptive effects of CO2 on small and larger damselfish recruits respectively, resulting from CO2-induced behavioural changes likely mediated by impaired neurological function. This study highlights the complexity of predicting the effects of climate change on coral reef ecosystems.