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.

Seasonal and local spatial patterns in the upper thermal limits of corals on the inshore Central Great Barrier Reef

Abstract: Experimental studies of the upper thermal limits of corals from Orpheus Island, an inshore reef in the central Great Barrier Reef, show that Acropora formosa has a 5-day 50%-bleaching threshold of between 31 and 32 °C in summer, only 2 to 3 °C higher than local mean summer temperatures (29 °C). Summer bleaching thresholds for Pocillopora damicornis and A. elseyi were 1 °C higher (between 32 and 33 °C). The winter bleaching threshold of Pocillopora damicornis was 1 °C lower than its summer threshold, indicating that seasonal acclimatisation may take place. This seasonal difference raises the possibility that at least some corals may be capable of short-term thermal acclimatisation. Neither P. damicornis nor A. elseyi showed habitat-specific (reef flat versus reef slope) differences in bleaching thresholds. Further, colonies of P. damicornis collected from sites 3 km apart also showed no difference in bleaching threshold despite populations of this species responding differently at these two sites during a natural bleaching event. The bleaching thresholds determined in this study are best considered as the maximum tolerable temperatures for local populations of these species because they were determined in the absence of additional stressors (e.g. high light) which often co-occur during natural bleaching events. We consider the 5-day 50% bleaching thresholds determined in these experiments to be fair indicators of upper thermal limits, because >50% of a sample population died when allowed to recover in situ. We found a delay of up to a month in the bleaching response of corals following thermal stress, a result that has implications for identifying the timing of stressful conditions in natural bleaching events.

Does increased habitat complexity reduce predation and competition in coral reef fish assemblages

Abstract: Greater habitat complexity is often associated with a greater abundance and diversity of organisms. High complexity habitats may reduce predation and competition, thereby allowing more individuals to occupy a given area. Using 16 spatially isolated reefs in the Bahamas, I tested whether increased habitat complexity reduced the negative effects of resident predators and competitors on recruitment and survival of a common damselfish. Two levels of habitat complexity were cross-factored with the presence or absence of two guilds of resident fishes: predators (sea basses and moray eels) and interference competitors (large territorial damselfishes). I monitored subsequent recruitment and recruit mortality for 60 days. Residents had strong negative effects on recruitment regardless of habitat complexity. In the presence of residents, recruits suffered high mortality immediately after settlement that was similar on low and high complexity reefs, although high complexity reduced mortality of recruits that survived this early postsettlement period. Comparisons between shelter hole diameters and the sizes of residents suggest that territorial damselfishes and small resident predators could access most shelter holes, whereas large resident predators were excluded from many shelter holes. This study demonstrates that whether habitat complexity reduces predation and competition may depend on several key factors, such as the availability of appropriate shelter, behavioral attributes of interactors, and developmental stage of prey/inferior competitors.

Survival dynamics of scleractinian coral larvae and implications for dispersal

Abstract: Survival of pelagic marine larvae is an important determinant of dispersal potential. Despite this, few estimates of larval survival are available. For scleractinian corals, few studies of larval survival are long enough to provide accurate estimates of longevity. Moreover, changes in mortality rates during larval life, expected on theoretical grounds, have implications for the degree of connectivity among reefs and have not been quantified for any coral species. This study quantified the survival of larvae from five broadcast-spawning scleractinian corals (Acropora latistella, Favia pallida, Pectinia paeonia, Goniastrea aspera, and Montastraea magnistellata) to estimate larval longevity, and to test for changes in mortality rates as larvae age. Maximum lifespans ranged from 195 to 244 d. These longevities substantially exceed those documented previously for coral larvae that lack zooxanthellae, and they exceed predictions based on metabolic rates prevailing early in larval life. In addition, larval mortality rates exhibited strong patterns of variation throughout the larval stage. Three periods were identified in four species: high initial rates of mortality; followed by a low, approximately constant rate of mortality; and finally, progressively increasing mortality after approximately 100 d. The lifetimes observed in this study suggest that the potential for long-distance dispersal may be substantially greater than previously thought. Indeed, detection of increasing mortality rates late in life suggests that energy reserves do not reach critically low levels until approximately 100 d after spawning. Conversely, increased mortality rates early in life decrease the likelihood that larvae transported away from their natal reef will survive to reach nearby reefs, and thus decrease connectivity at regional scales. These results show how variation in larval survivorship with age may help to explain the seeming paradox of high genetic structure at metapopulation scales, coupled with the maintenance of extensive geographic ranges observed in many coral species.

Phylogenetic Classification of Ericaceae: Molecular and Morphological Evidence

Abstract: A new classification of Ericaceae is presented based on phylogenetic analyses of nuclear and chloroplast DNA sequence data, morphology, anatomy, and embryology. Eight subfamilies and 20 tribes are recognized. In this classification Epacridaceae are included as Styphelioideae and Empetraceae as tribe Empetreae within the Ericoideae. The herbaceous taxa previously recognized as Pyrolaceae and Monotropaceae by some authors are also included within Ericaceae, in the subfamily Monotropoideae. A key, morphological descriptions, and representative images are provided for all named groups. Two new combinations inKalmia (K. buxifolia andK. procumbens) are made, and three new taxa are described: Oligarrheneae, Richeeae, and Cosmelieae (all within Styphelioideae).

Development of swimming abilities in reef fish larvae

Abstract: Recent studies have revealed that reef fish larvae have excellent sustained swimming capabilities and considerable potential for modifying their dispersal patterns by active swimming. However, these studies concentrate solely on the late pelagic phase. We examined the development of swimming abilities from hatching through to settlement in 3 reef fish species (Pomacentrus amboinensis, Sphaeramia nematoptera, Amphiprion melanopus). Larval rearing provided larvae at all stages of development. Experiments were conducted in flow chambers designed for measuring the critical and sustained swimming capability of young larvae. In all 3 species, critical swimming ability increased steadily with age, size, relative propulsive area and developmental stage of the larvae. In contrast, sustained swimming ability showed a marked inflection during development. Differences among species throughout development appear to reflect variations in the developmental patterns of the 3 species. Propulsive area was highly correlated with swimming ability and may prove useful for estimating swimming capabilities among species. The results suggest that some species have the potential to actively modify their dispersal patterns from an early age.