Slower Recovery Rate Research Articles

The importance of low atmospheric CO2 and fire in promoting the spread of grasslands and savannas

AbstractThe distribution and abundance of trees can be strongly affected by disturbance such as fire. In mixed tree/grass ecosystems, recurrent grass‐fuelled fires can strongly suppress tree saplings and therefore control tree dominance. We propose that changes in atmospheric [CO2] could influence tree cover in such metastable ecosystems by altering their postburn recovery rates relative to flammable herbaceous growth forms such as grasses. Slow sapling recovery rates at low [CO2] would favour the spread of grasses and a reduction of tree cover. To test the possible importance of [CO2]/fire interactions, we first used a Dynamic Global Vegetation Model (DGVM) to simulate biomass in grassy ecosystems in South Africa with and without fire. The results indicate that fire has a major effect under higher rainfall conditions suggesting an important role for fire/[CO2] interactions. We then used a demographic model of the effects of fire on mesic savanna trees to test the importance of grass/tree differences in postburn recovery rates. We adjusted grass and tree growth in the model according to the DGVM output of net primary production at different [CO2] relative to current conditions. The simulations predicted elimination of trees at [CO2] typical of the last glacial period (180 ppm) because tree growth rate is too slow (15 years) to grow to a fire‐proof size of ca. 3 m. Simulated grass growth would produce an adequate fuel load for a burn in only 2 years. Simulations of preindustrial [CO2] (270 ppm) predict occurrence of trees but at low densities. The greatest increase in trees occurs from preindustrial to current [CO2] (360 ppm). The simulations are consistent with palaeo‐records which indicate that trees disappeared from sites that are currently savannas in South Africa in the last glacial. Savanna trees reappeared in the Holocene. There has also been a large increase in trees over the last 50–100 years. We suggest that slow tree recovery after fire, rather than differential photosynthetic efficiencies in C3 and C4 plants, might have been the significant factor in the Late Tertiary spread of flammable grasslands under low [CO2] because open, high light environments would have been a prerequisite for the spread of C4 grasses. Our simulations suggest further that low [CO2] could have been a significant factor in the reduction of trees during glacial times, because of their slower regrowth after disturbance, with fire favouring the spread of grasses.

Spill Response that Benefits the Long-Term Recovery of Oiled Mangroves

ABSTRACT We revisited three sites in Florida and Puerto Rico that were oiled 23 to 29 years ago, analyzing them and the published literature to determine that mangroves follow a 6 to 25 year recovery cycle. We reviewed response methods and determined that the use of offshore dispersants, the booming of tidal creeks and inlets, the use of onshore sorbents, low-pressure flushing and the manual collection of oily debris provide benefits for recovery at least in the short term. Non-beneficial response efforts that have degraded mangroves include forest cutting, heavy equipment and personnel traffic, tree burning, onshore use of chemicals, and plantings in toxic soil. Perhaps the most detrimental response effort studied was the impoundment of basin forests that has resulted in long-term losses and slow recovery rates. The intertidal use of dispersants has been shown to be beneficial to mangroves, however their use has also caused damages to nearshore environments such as coral reefs. In summary, once the oil has reached sheltered mangrove forests there exist only short-term benefits from traditional response efforts. More likely there are only non-beneficial results compared to natural attenuation. We conclude that the only longterm beneficial response method appears to be a combination of non-intrusive oil collection and booming techniques in heavily oiled, sheltered areas with closely monitored natural recovery in forests more lighly oiled. This should be paired with mitigation programs involving habitat creation either in unoiled areas or in the impact zone following the attenuation of oil and removal of debris from the deteriorating forests.

Impacts after four years of experimental trampling on alpine/sub-alpine environments in western Tasmania

Experimental trials were undertaken over four years to assess the impact of recreational trampling in undisturbed alpine and sub-alpine vegetation communities in the Western Arthur Range, western Tasmania. Data on ‘pad’ formation due to human trampling were collected using vegetation cover assessments, biomass estimates and detailed cross-sectional surface profiles. In sub-alpine buttongrass and alpine herbfield, prolonged and sustained damage may occur after 100 passes by walkers. The environmental threshold of the flat alpine herbfield site was breached after 200 passes. Plant morphology was one determinant of resistance and resilience, with upright woody shrubs and tall tussock graminoids most vulnerable to sustained trampling damage. Cushions are susceptible to trampling impacts at 500 passes. Loss of vegetation cover peaks 6–12 months after trampling. Our results show that pads formed with as few as 30–100 passes per annum and tracks form at between 100 and 500 passes per annum. Two years after the cessation of trampling, there is some small recovery in vegetation cover after 30 and 100 passes per annum applied for three years, but no evidence of recovery at the 500 pass treatments. The low trampling threshold and slow recovery rates in western Tasmania suggest that concentrating walkers on a minimal number of sites may be the best management option for these untracked alpine and sub-alpine environments.

Behavioral and electrophysiological responses of the brownbanded cockroach, Supella longipalpa, to stereoisomers of its sex pheromone, supellapyrone.

Females of the brownbanded cockroach, Supella longipalpa, release a sex pheromone (supellapyrone) during a calling behavior and attract males from a distance. Supellapyrone has four possible configurations resulting from two asymmetric carbons at positions 2 and 4 (i.e., 2R,4R; 2R,4S; 2S,4R; and 2S,4S), but only the RR isomer is produced by females. Using pure synthetic stereoisomers in field tests, we showed that males are attracted to RR but also to high concentrations of the isomer SR. To study the activity of the stereoisomers in more detail we developed behavioral and electroantennogram (EAG) dose-response curves for each. Behaviorally, RR was the most active isomer with just 0.3 pg delivered on a filter paper being sufficient to elicit 50% male response in the olfactometer. Males were also attracted to SR and SS in the olfactometer, but at much higher dosages (100x ) than the natural compound; RS did not elicit behavioral responses at any of the doses tested. In EAG assays, the antenna of male S. longipalpa showed high and similar sensitivity to RR and SR, but a much lower (10%) sensitivity to SS and practically no response to RS. The lack of agreement between behavioral and electrophysiological data suggested either that RR and SR stimulate different antennal sensory neuron types, or that some aspect of the interaction between the pheromone and the sensillum environment or the receptor neuron itself is different. To test the first hypothesis we examined the response of the antenna before and after adaptation with each of the four stereoisomers. Positive cross-adaptation between RR and SR suggests that these two compounds stimulate the same receptor cells. Therefore, the lack of agreement between behavioral and EAG dose-response curves could be explained by isomer-specific molecular interactions between the pheromone and the receptor neuron. Although RR and SR produced the same EAG amplitude, stimulation with SR resulted in a slower recovery rate (i.e., wider peaks) than stimulation with RR. To gain further understanding of the response specificity of the antennae to the different stereoisomers we compared EAG responses (amplitude and recovery time) in response to individual stereoisomers and binary mixtures of isomers. These tests showed additive responses of the EAG amplitude to mixtures of compounds, but nonadditive responses of EAG recovery time. Therefore, peak height and width are independent parameters of the EAG, probably representing different intrasensillar events, and likely resulting in the expression of different behavioral responses.

Cogongrass [ Imperata cylindrica (L.) Beauv.] response to herbicides and disking on a cutover site and in a mid-rotation pine plantation in southern USA

Cogongrass [ Imperata cylindrica (L.) Beauv.], an alien grass listed as a federal noxious weed, is invading the forestlands of the southeastern USA threatening their ecological and economic integrity. Two field studies were conducted to quantify the effects of herbicides and disking on cogongrass that had infested a cutover site and an adjacent 17-year-old loblolly pine stand. Foliar cover, foliar biomass and rhizome biomass were quantified at 6-month intervals for 2 years. Imazapyr and glyphosate were applied at rates up to 1.12 and 8.96 kg ai ha −1, respectively, as single or split applications. Disking was post, herbicide application on the cutover site only. Evidence for immature cogongrass swards was present in both studies, which led to significant temporal, or community-level growth effects for all three measured responses. With respect to main effects, the herbicide treatments temporarily controlled the cover and aboveground biomass, with an almost negligible impact on rhizome biomass, in the cutover study. Disking had no significant effect on foliar re-growth, but did decrease rhizome re-growth, across all levels of time and herbicide treatments. The split imazapyr treatment had the slowest recovery rate (31% of the control treatment), regardless of disking effects. All the herbicide treatments resulted in reduced cover, foliar biomass and rhizome biomass in the mid-rotation study, 12 months after treatment (12 MAT). However, recovery was evident at the end of 24 months. Comparison of herbicide treatments between the cutover and mid-rotation studies revealed that competition from the 17-year-old pines did not significantly enhance herbicide control of cogongrass, although there was a trend of lower biomass productivity associated with the mid-rotation study. For example, rhizome biomass was 26% lower for the control in the mid-rotation study when compared to the non-disked control in the cutover study, in terms of relative growth 2 years after treatment. The overall effect of disking, herbicides (single dose or split applications), and pine tree competition was to provide a “window for desirable plant re-establishment” that may last up to 2–3 years. Long-term control may be possible with repeated herbicide applications and the use of fast growing, evergreen trees that can provide continuous heavy shade.

Retrospective analysis of the response of soil and stream chemistry of a northern forest ecosystem to atmospheric emission controls from the 1970 and 1990 Amendments of the Clean Air Act.

The 1970 and 1990 Amendments of the Clean Air Act (CAAA) have resulted in a decline in acidic deposition in the northeastern United States. Results from the application of a biogeochemical model (PnET-BGC) at the Hubbard Brook Experimental Forest in New Hampshire suggest that, without the implementation of the CAAAs, soil base saturation and soil solution molar Ca/Al ratio would decrease to values below 6% and 1.0, respectively, while S would continue to accumulate in organic matter and adsorbed pools at rates of 2 and 3 kg of S ha(-1) yr(-1), respectively. This scenario of conditions without the CAAAs was projected to result in higher stream concentrations of SO4(2-), NO3-, and Ca2+; monomeric Al; pH below 4.8; and acid-neutralizing capacity (ANC) less than -15 microequiv L(-1). The implementation of the CAAAs has led to a slight improvement in the soil base saturation, while recovery of soil solution Ca/Al cannot be fully assessed because of variability in observed values. Our evaluation of the relative benefits of the 1970 and 1990 CAAAs indicate that although the magnitude of the cumulative decrease in strong acid deposition was greater following the 1970 CAAA as compared to the 1990 CAAA, the extent of ecosystem recovery relative to the changes in acidic deposition suggests that the 1990 CAAA was also beneficial. The slow recovery rates might be the result of a legacy of chemical effects of acidic deposition for the last 150 years and suggests that additional controls in emissions might be required to show significant changes.

Salt Marsh Restoration in Connecticut: 20 Years of Science and Management

AbstractIn 1980 the State of Connecticut began a tidal marsh restoration program targeting systems degraded by tidal restrictions and impoundments. Such marshes become dominated by common reed grass (Phragmites australis) and cattail (Typha angustifolia and T. latifolia), with little ecological connection to Long Island Sound. The management and scientific hypothesis was that returning tidal action, reconnecting marshes to Long Island Sound, would set these systems on a recovery trajectory. Specific restoration targets (i.e., pre‐disturbance conditions or particular reference marshes) were considered unrealistic. However, it was expected that with time restored tides would return ecological functions and attributes characteristic of fully functioning tidal salt marshes. Here we report results of this program at nine separate sites within six marsh systems along 110 km of Long Island Sound shoreline, with restoration times of 5 to 21 years. Biotic parameters assessed include vegetation, macroinvertebrates, and use by fish and birds. Abiotic factors studied were soil salinity, elevation and tidal flooding, and soil water table depth. Sites fell into two categories of vegetation recovery: slow, ca. 0.5%, or fast, more than 5% of total area per year. Although total cover and frequency of salt marsh angiosperms was positively related to soil salinity, and reed grass stand parameters negatively so, fast versus slow recovery rates could not be attributed to salinity. Instead, rates appear to reflect differences in tidal flooding. Rapid recovery was characterized by lower elevations, greater hydroperiods, and higher soil water tables. Recovery of other biotic attributes and functions does not necessarily parallel those for vegetation. At the longest studied system (rapid vegetation recovery) the high marsh snail Melampus bidentatus took two decades to reach densities comparable with a nearby reference marsh, whereas the amphipod Orchestia grillus was well established on a slow‐recovery marsh, reed grass dominated after 9 years. Typical fish species assemblages were found in restoration site creeks and ditches within 5 years. Gut contents of fish in ditches and on the high marsh suggest that use of restored marsh as foraging areas may require up to 15 years to reach equivalence with reference sites. Bird species that specialize in salt marshes require appropriate vegetation; on the oldest restoration site, breeding populations comparable with reference marshland had become established after 15 years. Use of restoration sites by birds considered marsh generalists was initially high and was still nearly twice that of reference areas even after 20 years. Herons, egrets, and migratory shorebirds used restoration areas extensively. These results support our prediction that returning tides will set degraded marshes on trajectories that can bring essentially full restoration of ecological functions. This can occur within two decades, although reduced tidal action can delay restoration of some functions. With this success, Connecticut's Department of Environmental Protection established a dedicated Wetland Restoration Unit. As of 1999 tides have been restored at 57 separate sites along the Connecticut coast.

LONG ROADS AND TALL MOUNTAINS: THE IMPACT OF MOTHERHOOD ON THE RECOVERY AND HEALTH OF DOMESTIC ABUSE SURVIVORS

Using semistructured interviews with female domestic abuse survivors, in this study I investigated the relationships among female domestic abuse survivors' recovery from victimization, the influential effects of motherhood on the recovery process, and the real and perceived physical and psychological health of the survivor. Analysis of these relationships was undertaken to construct a better understanding of the health aspects of the female postvictimization experience and point out new areas of research investigation. When applied to the stress paradigm, findings indicate that abuse survivors who are also mothers may experience slower rates of recovery from abuse and lower physical and mental health status (both perceived and real) than victims who do not have children. Consequently, this may have an impact upon the survivor's children as well. Implications for further research are discussed.

Influence of long-term dormant-season burning and fire exclusion on ground-dwelling arthropod populations in longleaf pine flatwoods ecosystems

Frequent dormant-season prescribed burns were applied at 1-, 2- and 4-year intervals to longleaf pine stands, Pinus palustris, for over 40 years on the Osceola National Forest in Baker County, Florida. Control plots were unburned for the same period of time. Pitfall traps were operated from November 1994 to October 1999 to measure the short- and long-term effects of prescribed burning frequency on the relative abundance and diversity of ground-dwelling macroarthropods. We also measured dead and live plant biomass to determine how long-term frequent fires affected the structure of the forest floor. The average total dead plus live plant biomass was significantly higher on plots where fire had been excluded. Annual and biennial burning resulted in about the same amount of total plant biomass (dead and live plant material combined) which was significantly less than the quadrennially burned plots. Shannon diversity ( H′) and evenness of ground-dwelling arthropods were reduced by burning. Annually burned plots had the lowest diversity and evenness while biennially and quadrennially burned plots also were significantly lower than unburned control plots. Dormant-season burning did not increase the number of rare genera regardless of frequency. Percent similarity of arthropod communities was highest for comparisons between plots that had been burned (60–68%) and lowest for the comparison of annually burned plots to unburned controls (37%). Examination of diversity and similarity through time showed that changes were due to short-term effects caused by the application of fire and not long-term changes in the ground-dwelling arthropod community. Burning significantly reduced the numbers of predators regardless of fire frequency and resulted in an increased number of detritivores. A total of 42 genera were reduced by prescribed burning; 32 genera were captured in greater numbers on annually burned plots, and 11 genera had higher numbers in one or both of the intermediate burn frequencies (biennial or quadrennial). Twenty-six genera were captured in equal numbers on quadrennially and annually burned plots, but in significantly lower numbers than on unburned plots, demonstrating that 4 years was insufficient time for their populations to recover from mild dormant-season fires. Arthropod response to burning appeared to be species specific so attempts to generalize how arthropods will respond based on a few species or groups should be avoided. The slow recovery rate of so many species suggests that management oriented toward conservation of biodiversity in longleaf pine flatwoods should include areas of fire exclusion.

Rarity, specialization and extinction in primates

AimTo determine and explain biological traits that distinguish rare from common primate taxa.LocationAfrica, Americas, Asia, Madagascar.MethodsWe compare the biology of rare primate taxa with the biology of common taxa. Rarity is defined by (1) small size of geographic range; (2) small geographic range plus low local population density; and (3) small geographic range plus low local density plus narrow habitat specificity. After a linear comparison of size of geographic range with various biological traits, globally and by realm, extremes of rarity and commonness per realm are identified, and then combined for a global analysis. Tests are done both with genera treated as independent data points (n=62), and also with phylogenetic control by use of an independent contrasts test. Extinction risk in vertebrates, including primates, often correlates with high resource requirements, slow population recovery rate, and specialization. The three indices of rarity are therefore compared with these three general traits. Measures of resource use are body mass, local density, annual range size, and group size; of recovery rate, interbirth interval, and maximum intrinsic rate of natural population increase; and of degree of specialization, variety of diet, of habitats, maximum latitude, and morphological variety. All data come from the literature. Because several measures are compared, probabilities are Bonferroni corrected.ResultsIf rarity in primates correlates with any biological attribute, it consistently correlates with only measures of specialization, and not with measures of high resource use, or slow population recovery rate. Without phylogenetic correction, the first two indices of rarity associate significantly with all four measures of specialization, and the third with maximum latitude. With phylogenetic correction, the first index still associates with all four, the second with two (maximum latitude, number of species per genus), and the third shows no significant associations. While the four measures of specialization are strongly interrelated, stepwise regressions on geographic range indicate that maximum latitude has the strongest effect, followed by dietary variety and number of species per genus and, finally, habitat variety.Main conclusionsThe most commonly demonstrated traits of susceptibility to extinction are those of high resource use, slow recovery rate, and specialization. Yet, while rarity (almost however, it is defined) is an inevitable precursor to extinction, specialization is the only trait found to correlate with rarity in this study. We cannot explain this apparent contradiction.

All-optical clock division with mode-locked figure-eight laser based on the slow carrier recovery rate in semiconductor optical amplifier

With a mode-locked figure-eight laser, we demonstrate the clock division operation using a semiconductor optical amplifier (SOA) with a slow carrier recovery rate. We show stable clock division at 2.5 GHz and two output states at half the repetition rate of the 10 GHz input pulses. The forming pulses in the laser cavity will interact with each other at the onset of mode locking when the SOA in the laser has a relatively slow carrier recovery rate. A numerical model of the laser is built to simulate the generation of clock division.

TipE Regulates Na+-dependent Repetitive Firing in Drosophila Neurons

The tipE gene, originally identified by a temperature-sensitive paralytic mutation in Drosophila, encodes a transmembrane protein that dramatically influences sodium channel expression in Xenopus oocytes. There is evidence that tipE also modulates sodium channel expression in the fly; however, its role in regulating neuronal excitability remains unclear. Here we report that the majority of neurons in both wild-type and tipE mutant (tipE−) embryo cultures fire sodium-dependent action potentials in response to depolarizing current injection. However, the percentage of tipE− neurons capable of firing repetitively during a sustained depolarization is significantly reduced. Expression of a tipE+ transgene, in tipE− neurons, restores repetitive firing to wild-type levels. Analysis of underlying currents reveals a slower rate of repolarization-dependent recovery of voltage-gated sodium currents during repeated activation in tipE− neurons. This phenotype is also rescued by expression of the tipE+ transgene. These data demonstrate that tipE regulates sodium-dependent repetitive firing and recovery of sodium currents during repeated activation. Furthermore, the duration of the interstimulus interval necessary to fire a second full-sized action potential is significantly longer in single- versus multiple-spiking transgenic neurons, suggesting that a slow rate of recovery of sodium currents contributes to the decrease in repetitive firing in tipE− neurons.

Evaluation of the effects of future controls on sulfur dioxide and nitrogen oxide emissions on the acid–base status of a northern forest ecosystem

The integrated biogeochemical model, PnET-BGC, was used to simulate the response of soil and surface water at the reference watershed (W6) at the Hubbard Brook Experimental Forest, New Hampshire, to changes in atmospheric deposition. The performance of the model was assessed using two objective statistical criteria, the normalized mean absolute error, and the efficiency, in order to compare simulated results with observed values between 1980 and 1998. Model results showed good agreement with measured concentrations of stream Ca 2+, and SO 4 2−, while stream NO 3 − and Al concentrations and soil solution Ca/Al ratios were over predicted after 1990. Model simulations showed that there was some improvement in soil and stream chemistry in response to the 1990 Amendments to the Clean Air Act (CAAA) compared to conditions without this legislation. However, the 1990 CAAA will not result in substantial changes in critical indicators (e.g. soil base saturation, soil solution Ca/Al, stream pH, acid neutralizing capacity (ANC) and Al concentrations). The slow recovery rates suggest that additional reduction in strong acid inputs will be required to significantly alleviate ecosystem stress from acidic deposition. Simulation of the impact of equivalent reductions in SO 4 2− and NO 3 − deposition indicated slightly greater recovery under the SO 4 2− reductions compared with NO 3 −. An inter-annual pattern of stream NO 3 − concentrations suggests that nitrification under snowpack is a significant source of N in the ecosystem. Vegetation N uptake during summer greatly limits NO 3 − loss, and as a result, summer utility controls of NO x emissions will not significantly mitigate stream NO 3 − loss and associated surface water acidification.

Growth and condition in Australian fur seals (Arctocephalus pusillus doriferus) (Carnivora : Pinnipedia)

Mass and length growth models were determined for male (n = 69) and female (n = 163) Australian fur seals (Arctocephalus pusillus doriferus) collected at a breeding colony on Seal Rocks (38˚31′S, 145˚06′E), Bass Strait, in south-east Australia, between February and November during 1970–72. Growth was best described by the logistic model in males and the von Bertalanffy model in females. Asymptotic mass and length were 229 kg and 221 cm for males, and 85 kg and 163 cm for females. In all, 95% of asymptotic mass and length were attained by 11 years and 11 years, respectively, in males compared with 9 years and 5 years, respectively, in females. Males grew in length faster than females and experienced a growth spurt in mass coinciding with the onset of puberty (4–5 years). The onset of puberty in females occurs when approximately 86% of asymptotic length is attained. The rate of growth and sexual development in Australian fur seals is similar to (if not faster than) that in the conspecific Cape fur seal (A. p. pusillus), which inhabits the nutrient-rich Benguela current. This suggests that the low marine productivity of Bass Strait may not be cause of the slow rate of recovery of the Australian fur seal population following the severe over-exploitation of the commercial sealing era. Sternal blubber depth was positively correlated in adult animals with a body condition index derived from the residuals of the mass–length relationship (males: r2 = 0.38, n = 19, P < 0.001; females: r2 = 0.22, n = 92, P < 0.001), confirming the validity of using such indices on otariids. Sternal blubber depth varied significantly with season in adult animals. In males it was lowest in winter and increased during spring prior to the breeding season (r2 = 0.39, n = 19, P < 0.03) whereas in females it was greatest during winter (r2 = 0.05, n = 122, P< 0.05).

Microbial activity and nitrogen mineralization in forest mineral soils following heating: evaluation of post-fire effects

Heat generated during fire induces chemical oxidation of soil organic matter thereby altering carbon (C) and nitrogen (N) transformations. Prior soil fire history and soil moisture content at the time of heating can be confounding factors in the interpretation of the influence of heat on soil processes. In this study we evaluated how soil heating (160 and 380°C) under three moisture regimes (−0.03, −1.0, and −1.5 MPa) influences microbial activity and N mineralization in two soils: (1) not exposed to fire for the past 80 years, (2) recently exposed to wildfire. Initially, the fire exposed soil had lower basal respiration rates and lower concentrations of microbial biomass C, potentially mineralizable nitrogen (PMN), soluble hexose sugars, and NH 4 +–N, but higher NO 3 −–N concentrations than the soil not exposed to fire. Both soils responded similarly to elevated temperatures. Higher temperatures resulted in greater microbial mortality and a greater release of soluble sugars and NH 4 +–N. PMN concentrations increased at 160°C, but decreased at 380°C in both soils. The highest NH 4 +–N concentrations were observed in soils not previously exposed to fire that were incubated at −0.03 MPa after heating. Soils previously exposed to fire had low NH 4 +–N concentrations and high NO 3 −–N concentrations. Heating at low soil water potentials resulted in elevated concentrations of microbial biomass C and soluble sugars, and lower NH 4 +–N and NO 3 −–N concentrations. Initial C availability appeared to be an important factor in the recovery of microbial biomass during 14-d post-heating incubation, which was greatest after heating at 380°C and −1.5 MPa. Both soils demonstrated slow rates of recovery of nitrifying organisms despite high rates of net NH 4 +–N accumulation. It appears that low soil water potential at the time of heat exposure reduces losses of mineralizable N.

The response of Acropora hyacinthus and Montipora tuberculosa to three different types of colony damage: scraping injury, tissue mortality and breakage

Three types of injuries commonly generated by biotic and abiotic agents on the periphery of coral colonies are tissue mortality, scraping injuries and breakage. To determine if recovery (amount of regeneration) was affected by injury type, colonies of Acropora hyacinthus and Montipora tuberculosa were inflicted with tissue, scraping and breakage injuries and their recovery monitored over 24 days. The influence of the tissue available for regeneration (i.e. the zone of tissue of bordering or partially injured polyps from which regeneration can occur) and the amount of settlement of algae on recovery was also measured for the different injury types and species. Overall, the amount of regeneration was up to four times greater for a scraping injury than tissue mortality and breakage. Furthermore, the amount of regeneration of the breakage injuries was approximately two-times greater for M. tuberculosa than for A. hyacinthus colonies. The regeneration rate of all injury types declined over time for both species. Recovery of injuries was influenced by the amount of algae that colonised the lesion and the zone of tissue available for regeneration. In general, the amount of regeneration of injuries was lower for injuries with a small zone of basal tissue available for regeneration, and the amount of regeneration was negatively correlated with the amount of algal settlement. The results of this study are important for understanding the role of partial mortality in the demography of scleractinian corals. Injuries impact on the population dynamics of colonies because regenerative processes require resources usually available for other processes (e.g. growth and reproduction), and slow recovery rates potentially increase the chance of whole colony mortality.

Are deepwater fisheries sustainable? — the example of orange roughy ( Hoplostethus atlanticus) in New Zealand

The deepsea environment is generally regarded as being one of low energy and productivity. Species exploited at depths of over 600 m like orange roughy ( Hoplostethus atlanticus), oreos (e.g. Allocyttus niger, Pseudocyttus maculatus), and macrourid rattails (e.g. Coryphaenoides rupestris, Macrourus berglax) have slow growth rates and high longevity compared to traditional commercial species from the continental shelf. They have low levels of sustainable yields, are vulnerable to overfishing, and have slow recovery rates. Yet, they are often high-value species, and this has maintained interest in developing new fisheries for deepwater species. In New Zealand waters orange roughy has been fished for 20 years. Familiar patterns of rapid fishery development with large catches, followed by contractions in stock distribution, and reductions in catch levels as the stocks become over-exploited, have occurred. Quotas in a number of New Zealand fisheries were reduced in the early 1990s, and this enables an insight into how stocks respond with reduced levels of exploitation, and how resilient and sustainable these fisheries may be in the long term. Examples are given for several New Zealand and Australian orange roughy fisheries. Changes in abundance, fishery performance, and biological characteristics are examined. In some cases fish stocks appear to be holding their own, and are supporting relatively stable catch rates, but in others stocks are still declining. There are few signs of biological compensation, and recruitment levels appear to be low. Lack of good data on levels and patterns of recruitment is a major source of uncertainty in current stock assessments, and a principal concern for long term sustainability of such fisheries

Patterns of recovery from trauma: the use of intraindividual analysis.

Patterns of recovery from sexual and nonsexual assault were examined. Two studies containing data from female victims of these assaults were analyzed. In Study 1, victims (N = 101) underwent 12 weekly assessments with measures of posttraumatic stress disorder (PTSD), depression, and state anxiety. In Study 2, victims (N = 108) underwent monthly assessments on the same measures. The authors examined the effects of type of trauma and time of peak reaction on long-term recovery using intraindividual analysis of change. In both studies, initial and peak reactions of rape victims were more severe than were those of nonsexual assault victims on all measures of psychopathology. Victims with delayed peak reaction exhibited more severe pathology at the final assessment than did victims with early peak reaction. Results of Study 2 indicated a slower recovery rate from sexual than nonsexual assault; in Study 1 a similar pattern of recovery emerged. The advantages of an individual-focused, longitudinal approach to recovery from a trauma are discussed.

Delirium on hospital admission in aged hip fracture patients: prediction of mortality and 2-year functional outcomes.

Hip fracture patients are at increased risk of confusion or delirium due to the trauma associated with the injury and the rapid progression to hospitalization and surgery, in addition to the pain and loss of function experienced. Hip fracture patients who develop delirium may require longer hospital stays, are more often discharged to long-term care, and have a generally poor prognosis for returning home or regaining function in activities of daily living (ADL). The present study examines the impact of delirium present on hospital admission in a sample of 682 non-demented, aged hip fracture patients residing in the community at the time of their fracture. In-hospital assessments designed to assess both prefracture and postfracture functioning, as well as follow-up interviews at 2, 6, 12, 18, and 24 months postfracture, were obtained from participants. Analyses indicate that baseline or admission delirium is an important prognostic predictor of poor long-term outcomes in persons without known cognitive impairment, after controlling for age, gender, race, comorbidity, and functional status. Delirium at admission (i.e., prior to surgery) was associated with poorer functioning in physical, cognitive, and affective domains at 6 months postfracture and slower rates of recovery. Impairment and delays in recovery may be further exacerbated by increased depressive symptoms in confused patients over time. Delirium on hospital admission was not a significant predictor of mortality after adjustment for confounding factors. The present findings further emphasize the significance of immediate detection and treatment of delirium in hip fracture patients to ameliorate the short and long-term effects of acute confusion on functional outcomes.

Quantifying a new form of acoustic creep in rocks and concrete

A new form of nonlinear elastic response, which we call ‘‘slow dynamics,’’ has recently been found to scale universally in all sandstones, limestone, and concretes we have tested. Slow dynamics is unique among known creep processes; the elastic modulus and inverse loss tangent drop in response to harmonic acoustic stress, so the response violates the symmetry of the source. We show here that the slow dynamic recovery rate is a function of temperature, consistent with a thermal activation model for creep requiring a spectrum of energy barriers. We also show that short-term modulus drop, with slow dynamic recovery, accompanies temperature change of either sign, again violating the source symmetry. These two modes of activation are compared quantitatively, and suggest a common origin for slow dynamics in disequilibrated internal strain fields. [Work supported by the Department of Energy: Office of Basic Energy Sciences and IGPP, the Institute for Geophysics and Planetary Physics at Los Alamos.]