Coral–macroalgal phase shifts or reef resilience: links with diversity and functional roles of herbivorous fishes on the Great Barrier Reef

Changes from coral to macroalgal dominance following disturbances to corals symbolize the global degradation of coral reefs. The development of effective conservation measures depends on understanding the causes of such phase shifts. The prevailing view that coral–macroalgal phase shifts commonly occur due to insufficient grazing by fishes is based on correlation with overfishing and inferences from models and small-scale experiments rather than on long-term quantitative field studies of fish communities at affected and resilient sites. Consequently, the specific characteristics of herbivorous fish communities that most promote reef resilience under natural conditions are not known, though this information is critical for identifying vulnerable ecosystems. In this study, 11 years of field surveys recorded the development of the most persistent coral–macroalgal phase shift (>7 years) yet observed on Australia’s Great Barrier Reef (GBR). This shift followed extensive coral mortality caused by thermal stress (coral bleaching) and damaging storms. Comparisons with two similar reefs that suffered similar disturbances but recovered relatively rapidly demonstrated that the phase shift occurred despite high abundances of one herbivore functional group (scraping/excavating parrotfishes: Labridae). However, the shift was strongly associated with low fish herbivore diversity and low abundances of algal browsers (predominantly Siganidae) and grazers/detritivores (Acanthuridae), suggesting that one or more of these factors underpin reef resilience and so deserve particular protection. Herbivorous fishes are not harvested on the GBR, and the phase shift was not enhanced by unusually high nutrient levels. This shows that unexploited populations of herbivorous fishes cannot ensure reef resilience even under benign conditions and suggests that reefs could lose resilience under relatively low fishing pressure. Predictions of more severe and widespread coral mortality due to global climate change emphasize the need for more effective identification and protection of ecosystem components that are critical for the prevention of coral reef phase shifts.     

Cure by age and stage at diagnosis for colorectal cancer patients in North West England, 1997–2004: A population-based study

Background: Stage and age at diagnosis are important prognostic factors for patients with colorectal cancer. However, the proportion cured by stage and age is unknown in England. Materials and methods: This population-based study includes 29,563 adult patients who were diagnosed and registered with colorectal cancer during 1997–2004 and followed till 2007 in North West England. Multiple imputation was used to provide more reliable estimates of stage at diagnosis, when these data were missing. Cure mixture models were used to estimate the proportion ‘cured’ and the median survival of the uncured by age and stage. Results: For both colon and rectal cancer the proportion of patients cured and median survival time of the uncured decreased with advancing stage and increasing age. Patients aged under 65 years had the highest proportion cured and longest median survival of the uncured. Conclusion: Cure of colorectal cancer patients is dependent on stage and age at diagnosis with younger patients or those with less advanced disease having a better prognosis. Further efforts are required, in order to reduce the proportion of patients presenting with stage III and IV disease and ultimately increase the chance of cure.     

Review of “Marine Hard Substrates: Colonization and Evolution,” a Thematic Session at the Geological Society of America Annual Meeting,Denver, USA,November 7–10, 2004

Planolites, although strictly a junior synonym of Palaeophycus, can be retained as a valid ichnotaxon on the basis of stability of nomenclature. As emended by Pemberton and Frey (1982) and consistently adopted by later authors, Planolites is diagnosed primarily on the basis that it is an unlined simple burrow, whereas Palaeophycus is a lined burrow. Other ichnotaxobases and ethological considerations are, without exception, subordinate to this directive.     

Wood usage and its influence on the environment from the Neolithic until the Iron Age: a case study of the graves at Flintbek (Schleswig–Holstein, Northern Germany)

The investigated area near Flintbek (Schleswig–Holstein, Northern Germany) was used as a burial ground from the Neolithic until the Iron Age. Due to modern agriculture, the above-ground funerary monuments have been destroyed. Rescue excavations from 1976 to 1996 recovered the archaeological remains. In addition to the archaeological reassessment of the findings, further scientific analyses were carried out. The results of the charcoal analyses are presented in this paper. The overall spectrum of wood species represents the typical species composition of mixed oak forests. Over the whole investigated time span (Neolithic–Iron Age) these species alternate with a second group of taxa: species benefiting from better light conditions. In times of intensive human impact, these light-demanding taxa gained considerable importance, showing the opening of the wooded landscape. In phases with less human impact, a regeneration of mixed oak forest is detectable. For the Neolithic it was possible to develop a more detailed picture of wood usage based on 162 radiocarbon dates of 106 samples. These illustrate considerable changes during the Neolithic, which resulted in a varied pattern of open land and closed forest influenced by human presence and land use. Another important aspect of the Flintbek area is the handling of samples deriving from different contexts. While charcoal samples related to fire usage or grave constructions contain only slight contamination, samples from fillings (pits, burial layers) are characterized by charcoal dating being either too old or even too young for the archaeological context.