Climate change, coral bleaching and the future of the world's coral reefs

Sea temperatures in many tropical regions have increased by almost 1 degrees C over the past 100 years, and are currently increasing at similar to 1-2 degrees C per century. Coral bleaching occurs when the thermal tolerance of corals and their photosynthetic symbionts (zooxanthellae) is exceeded. Mass coral bleaching has occurred in association with episodes of elevated sea temperatures over the past 20 years and involves the loss of the zooxanthellae following chronic photoinhibition. Mass bleaching has resulted in significant losses of live coral in many parts of the world. This paper considers the biochemical, physiological and ecological perspectives of coral bleaching. It also uses the outputs of four runs from three models of global climate change which simulate changes in sea temperature and hence how the frequency and intensity of bleaching events will change over the next 100 years. The results suggest that the thermal tolerances of reef-building corals are likely to be exceeded every year within the next few decades. Events as severe as the 1998 event, the worst on record, are likely to become commonplace within 20 years. Most information suggests that the capacity for acclimation by corals has already been exceeded, and that adaptation will be too slow to avert a decline in the quality of the world's reefs. The rapidity of the changes that are predicted indicates a major problem for tropical marine ecosystems and suggests that unrestrained warming cannot occur without the loss and degradation of coral reefs on a global scale.

Is there change over time in the season-of-birth effect for schizophrenia? Data from the southern hemisphere

The aim of this paper is to examine distributions of schizophrenia and general population births over time in order to determine whether (a) the pattern has changed over time, (b) any pattern was similar for both males and females, and (c) whether there is any indication that there is any relationship between the changes in pattern between schizophrenia and general population births. Birth month and year for 7807 individuals with ICD8/9 schizophrenia were gained from the Queensland Mental Health Statistical System for 1914-1975. Monthly births for the general population in Queensland for the same period were obtained from the Australian Bureau of Statistics. For each decade we obtained two comparisons, (1) between two 'seasons' (summer-autumn/winter-spring), and (2) between the third (coldest) quarter and the remaining quarters. Based on expected contrasts from general population proportions, odds ratios and their confidence intervals were used to analyse these comparisons for all subjects, and for males and females separately. The seasonality found in our previous studies was again evident (OR 1.09; 95% CI= 1.01-1.17). However there was no significant change in its pattern over time either for the total group or for males and females separately. When the general population births alone were examined using the same contrasts, seasonality was also observed, but here there were fluctuations over time. These results suggest that exposures linked to changes in general population births over time should be examined in disorders such as schizophrenia which demonstrate seasonality in births. The Stanley Foundation supported this project.

Central projections of Drosophila sensory neurons in the transition from embryo to larva

Sensory axons of different sensory modalities project into typical domains within insect ganglia. Tactile and gustatory axons project into a ventral layer of neuropil and proprioceptive afferents, including chordotonal axone, into an intermediate or dorsal layer. Here, we describe the central projections of sensory neurons in the first instar Drosophila larva, relating them to the projection of the same sensory afferents in the embryo and to sensory afferents of similar type in other insects. Several neurons show marked morphologic changes in their axon terminals in the transition between the embryo and larva. During a short morphogenetic period late in embryogenesis, the axon terminals of the dorsal bipolar dendrite stretch receptor change their shape and their distribution within the neuromere. In the larva, external sense organ neurons (es) project their axons into a ventral layer of neuropil. Chordotonal sensory neurons (ch) project into a slightly more dorsal region that is comparable to their projection in adults. The multiple dendrite (md) neurons show two distinctive classes of projection. One group of md neurons projects into the ventral-most neuropil region, the same region into which es neurons project. Members of this group are related by lineage to es neurons or share a requirement for expression of the same proneural gene during development. Other md neurons project into a more dorsal region. Sensory receptors projecting into dorsal neuropil possibly provide proprioceptive feedback from the periphery to central motorneurons and are candidates for future genetic and cellular analysis of simple neural circuitry. J. Comp. Neurol. 425:34-44, 2000. (C) 2000 Wiley-Liss, Inc.

The effects of change in lead stimulus modality on the modulation of acoustic blink startle

In two experiments we investigated the effect of generalized orienting induced by changing the modality of the lead stimulus on the modulation of blink reflexes elicited by acoustic stimuli. In Experiment 1 (n = 32), participants were presented with acoustic or visual change stimuli after habituation training with tactile lead stimuli. In Experiment 2 (n = 64), modality of the lead stimulus (acoustic vs. visual) was crossed with experimental condition (change vs. no change). Lead stimulus change resulted in increased electrodermal orienting in both experiments. Blink latency shortening and blink magnitude facilitation increased from habituation to change trials regardless of whether the change stimulus was presented in the same or in a different modality as the reflex-eliciting stimulus. These results are not consistent with modality-specific accounts of attentional startle modulation.

Effect of removing user fees on attendance for curative and preventive primary health care services in rural South Africa

User fees are used to recover costs and discourage unnecessary attendance at primary care clinics in many developing countries. In South Africa, user fees for children aged under 6 yea rs and pregnant women were removed in 1994, and in 1997 all user fees at all primary health care clinics were abolished. The intention of these policy changes was to improve access to health services for previously disadvantaged communities. We investigated the impact of these changes on clinic attendance patterns in Hlabisa health district. Average quarterly new registrations and total attendances for preventive services (antenatal care, immunization, growth monitoring) and curative services (treatment of ailments) at a mobile primary health care unit were studied from 1992 to 1998. Regression analysis was undertaken to assess whether trends were statistically significant. There was a sustained increase in new registrations (P = 0.0001) and total attendances (P = 0.0001)for curative services, and a fall in new registrations (P = 0.01) and total attendances for immunization and growth monitoring (P = 0.0002) over the study period. The upturn in demand for curative services started at the time of the first policy change. The decreases in antenatal registrations (P = 0.07) and attendances (P = 0.09) were not statistically significant The number of new registrations for immunization and growth monitoring increased following the first policy change but declined thereafter. We found no evidence that the second policy change influenced underlying trends. The removal of user fees improved access to curative services but this may have happened at the expense of some preventive services. Governments should remain vigilant about the effects of new health policies in order to ensure that objectives are being met.

Change in the rate of shell deposition and shell microstructure in response to shell borers in the abalone Haliotis rubra

Gastropod shells consist of two crystal types of calcium carbonate, an outer, prismatic calcite layer and an inner nacreous layer made of aragonite. In cross-section, the nacre of the nacreous layer appears to have a regular brick-like microstructure composed of thin laminae of aragonite crystals, separated by very thin sheets of protein (Lutz and Rhoads, 1980; Nakahara, 1983). In abalone (Genus, Haliotis) and other gastropods, thin layers of non-lamellar pigmented material occur within the nacre and have been termed alternatively, fine lines, growth rings or growth lines (Shepherd et al., 1995). It has been suggested that these pigmented layers are small, prismatic, calcite layers (Shepherd and Avalos-Borja, 1997; Zaremba et al., 1996) but investigations using a Raman laser in Haliotis rubra show that they contain aragonite rather than calcite (Hawkes et al, 1996). Day and Fleming (1992) suggest that the occurrence of pigmented layers is correlated with regular exogenous cues such as reproduction or temperature changes and indeed in some species, pigmented layers in the shell can be used to age abalone (review: Shepherd and Triantafillos, 1997). However, McShane and Smith (1992) suggest that pigmented layers can occur irregularly and therefore may be unreliable indicators of age.

A spectral-based cusum test of evolutionary change

We develop a test of evolutionary change that incorporates a null hypothesis of homogeneity, which encompasses time invariance in the variance and autocovariance structure of residuals from estimated econometric relationships. The test framework is based on examining whether shifts in spectral decomposition between two frames of data are significant. Rejection of the null hypothesis will point not only to weak nonstationarity but to shifts in the structure of the second-order moments of the limiting distribution of the random process. This would indicate that the second-order properties of any underlying attractor set has changed in a statistically significant way, pointing to the presence of evolutionary change. A demonstration of the test's applicability to a real-world macroeconomic problem is accomplished by applying the test to the Australian Building Society Deposits (ABSD) model.

Spatial and temporal variation in distribution of mangroves in Moreton Bay, subtropical Australia: a comparison of pattern metrics and change detection analyses based on aerial photographs

An assessment of the changes in the distribution and extent of mangroves within Moreton Bay, southeast Queensland, Australia, was carried out. Two assessment methods were evaluated: spatial and temporal pattern metrics analysis, and change detection analysis. Currently, about 15,000 ha of mangroves are present in Moreton Bay. These mangroves are important ecosystems, but are subject to disturbance from a number of sources. Over the past 25 years, there has been a loss of more than 3800 ha, as a result of natural losses and mangrove clearing (e.g. for urban and industrial development, agriculture and aquaculture). However, areas of new mangroves have become established over the same time period, offsetting these losses to create a net loss of about 200 ha. These new mangroves have mainly appeared in the southern bay region and the bay islands, particularly on the landward edge of existing mangroves. In addition, spatial patterns and species composition of mangrove patches have changed. The pattern metrics analysis provided an overview of mangrove distribution and change in the form of single metric values, while the change detection analysis gave a more detailed and spatially explicit description of change. An analysis of the effects of spatial scales on the pattern metrics indicated that they were relatively insensitive to scale at spatial resolutions less than 50 m, but that most metrics became sensitive at coarser resolutions, a finding which has implications for mapping of mangroves based on remotely sensed data. (C) 2003 Elsevier Science B.V. All rights reserved.

The human organization of time: Temporal realities and experience (Book)

Reviews the book "The Human Organization of Time: Temporal Realities and Experience," by Allen C. Bluedorn.

Late Quaternary Milankovitch-scale climatic change and variability and its impact on monsoonal Australasia

Four pollen and charcoal records derived from marine cores around the northern perimeter of Australia are examined to provide a regional picture of patterns, causes and impacts of climate change over the last 100-300 ka. The availability of radiocarbon dates and oxygen isotope records for the cores provides primary chronological control. Spectral analysis of components of these records demonstrates an overall importance of Milankovitch frequencies with clear glacial-interglacial cyclicity dominated by variation in precipitation. In addition, a number of pollen taxa, as well as charcoal particles, exhibit a 30 ka frequency that is considered, from its relationship with biomass burning and with results of past modelling, to reflect changes in the intensity of El Nino-Southern Oscillation (ENSO) variability. Pollen components of all records show a decline, frequently stepwise, in more fire-sensitive vegetation and its replacement with more fire-tolerant vegetation. There is some evidence that this trend is linked to an onset or general increase in ENSO activity and perhaps also to variation in monsoon activity dating from about 300 ka BP that was caused by changes to oceanic circulation within the Indonesian region. The trend may have accelerated within the last 45 ka due to burning by indigenous people. (C) 2003 Elsevier B.V. All rights reserved.

Effects of restricted cochlear lesions in adult cats on the frequency organization of the inferior colliculus

Restricted cochlear lesions in adult animals result in plastic changes in the representation of the lesioned cochlea, and thus in the frequency map, in the contralateral auditory cortex and thalamus. To examine the contribution of subthalamic changes to this reorganization, the effects of unilateral mechanical cochlear lesions on the frequency organization of the central nucleus of the inferior colliculus (ICC) were examined in adult cats. Lesions typically resulted in a broad high-frequency hearing loss extending from a frequency in the range 15-22 kHz. After recovery periods of 2.5-18 months, the frequency organization of ICC contralateral to the lesioned cochlea was determined separately for the onset and late components of multiunit responses to tone-burst stimuli. For the late response component in all but one penetration through the ICC, and for the onset response component in more than half of the penetrations, changes in frequency organization in the lesion projection zone were explicable as the residue of prelesion responses. In half of the penetrations exhibiting nonresidue type changes in onset-response frequency organization, the changes appeared to reflect the unmasking of normally inhibited inputs. In the other half it was unclear whether the changes reflected unmasking or a dynamic process of reorganization. Thus, most of the observed changes were explicable as passive consequences of the lesion, and there was limited evidence for plasticity in the ICC. The implications of the data with respect to the primary locus of the changes and to the manner in which they contribute to thalamocortical reorganization are considered. (C) 2003 Wiley-Liss, Inc.

Management are aliens! Rumours during organisational change

Rumors collected from a large public hospital undergoing change were content analyzed, and a typology comprising the following five broad types of change-related rumors was developed: rumors about changes to job and working conditions, nature of organizational change, poor change management, consequences of the change for organizational performance, and gossip-rumors. Rumors were also classified as positive or negative on the basis of their content. As predicted, negative rumors were more prevalent than positive rumors. Finally, employees reporting negative rumors also reported more change-related stress as compared to those who reported positive rumors and those who did not report any rumors. The authors propose that rumors be treated as verbal symbols and expressions of employee concerns during organizational change.

Structural change, balance-of-payments constraint, and economic growth: evidence from the multisectoral Thirlwall`s law

This paper contributes to the literature on balance-of-payments constrained growth by investigating how structural change identified with changes in the sectoral composition of exports and imports affects the external constraint We test both the original and a multisectoral version of Thirlwall`s law for a sample of Latin American and Asian countries The original Thirlwall s law is found to hold for all sample countries except South Korea, whereas the multisectoral analogue holds for all of them As the sectoral composition of exports and imports is found to matter for growth we analyze the evolution of each country`s weighted trade income elasticities