Surface-feeding on cephalopods by procellariiform seabirds in the southern Benguela region, South Africa

Cephalopod beaks recovered from stomach samples taken from 14 seabird species in the southern Benguela region off Southern Africa and from one species at Sub-Antarctic Marion Island, were identified as far as possible, counted and the lower rostral lengths (LRLs) measured. Dorsal mantle lengths (DMLs) and body masses of the cephalopods eaten were estimated. The results of analyses by percentage frequency of occurrence and numerical abundance are discussed with reference to present knowledge of the distribution of cephalopods eaten by seabirds in the areas studied. Division of the cephalopod component of seabird diets into species which float, and species which sink, after death indicates that the birds forage on dead or moribund cephalopods on the surface, rather than catching live bioluminescent cephalopods at night.     

Small mammal responses to pyric successional changes in eucalypt forest

Sixteen 1-ha study plots covering five regeneration stages were simultaneously trapped five times over a 20-month period to provide data on small mammal response to vegetation changes following fire. Areas regenerating after fires from 9 years to 1 month before the investigation were sampled in a uniform open forest on a coastal sand plain. Two types of understorey were recognized: one dominated by true forest shrubs with which Rattus fuscipes, Antechinus stuartii and Sminthopsis murina were associated, and another dominated by heath elements where the addition of Pseudomys novaehollandiae and Mus musculus produced a significantly more diverse small mammal community. The two communities exhibited different responses to post-fire vegetation changes. Rattus fuscipes was the most abundant species and showed a logistic growth in biomass. No resident populations were established in the first 3 years, but a rapid increase in biomass occurred from 3 to 5 years to plateau after 8 years. Regeneration age had the greatest effect on R. fuscipes biomass mediated through the amount of accumulated leaf litter with additional variation being attributed to several vegetation structure variables and plant species diversity. A replacement sequence in time was observed for species reaching their maximum abundance (P. novaehollandiae and/or M. musculus → S. murina → A. stuartii → R. fuscipes) and was interpreted as species occupying stages in the succession when their optimal habitat requirements were fulfilled. These results have important implications for the design of management policies using fire or fire regimes as tools for habitat maintenance or alteration. A mosaic of forest patches of adequate size covering the entire range of seral stages is necessary to meet the optimum requirements of all the above species.     

Distributions of lizard species across edges delimiting open‐forest and sand‐mined areas

Abstract The distributions of lizards across habitat edges delimiting open‐forest and regenerating sand‐mined areas as a function of distance from the edge were studied at Tomago, New South Wales, Australia. Pitfall‐trapping was used to survey lizards across the northern edges of four forest fragments, to determine if lizards displayed characteristic responses across the edge, and whether these could be explained by the different habitat conditions. At each site, 11 equally spaced drift fences (each parallel to the edge) were arranged in a transect running perpendicular to the edge, and stretching 50 m into each habitat type. Captures of Amphibolurus muricatus (Agamidae) decreased substantially across the edge from the mine‐path to the forest so that it was identified as a mine‐path specialist lizard species. Captures of two skink species decreased across the mine‐path before reaching the edge, and were not caught (Ctenotus taeniolatus) or were seldom caught (Ctenotus robustus) in the forest, so they were identified as mine‐path specialist, edge avoiding, lizard species. Captures of Lampropholis delicata (Scincidae) increased across edges into the forest, consistent with the expectation for a forest specialist. Regression analyses indicated the responses to edges of three lizard species (A. muricatus, C. robustus and C. taeniolatus) were negatively correlated with canopy cover (probably due to its influence on temperature, as captures of A. muricatus and C. robustus were also correlated positively with mean daily temperature). In addition, the response of C. robustus correlated negatively with a vegetation factor (dense, even vegetation in the first 50 cm from ground level). The response of L. delicata correlated positively with understorey height. We have identified edge response strategies for four species of lizards across edges delimiting temperate open‐forest and mined areas, and identified habitat and microclimate variables that may have driven these responses.     

The effect of vibrissa deprivation pattern on the form of plasticity induced in rat barrel cortex

Plasticity was induced in the barrel cortex of adolescent rats by depriving every second vibrissa on the contralateral vibrissa pad.This produced a chessboard pattern of barrels in the cortex where each barrel receiving its principal input from a spared vibrissa was surrounded by barrels for which the principal vibrissa had been deprived and conversely, each barrel receiving its principal input from a deprived vibrissa was surrounded by barrels for which the principal vibrissa had been spared. After 7 days' deprivation, responses to the regrown vibrissae were depressed in layers II/III (49% of control levels) and IV (60%). Depression was far greater than that seen with "all vibrissa" deprivation, suggesting that activity in the spared vibrissae accentuated the depression of the deprived vibrissae. Depression was not due to subcortical changes as thalamic Ventral Posterior Medial (VPM) responses to deprived vibrissa were unchanged. The short latency responses in layer IV (5-7 ms) were unaffected by deprivation, but the number of cells responding at intermediate latencies (8-13 ms) was markedly reduced (to 66% of control). Potentiation of the spared vibrissa response was substantial in the near side of the neighbouring barrel (2.2-fold increase in layers II/III, 2.9-fold in layer IV) but had not spread to the far side after 7 days' deprivation. Sparing multiple vibrissae may increase the rate of potentiation since 7 days is insufficient time for potentiation in single vibrissa spared animals. Potentiation was not due to subcortical changes as thalamic VPm responses to the spared vibrissa were normal. However, in the spared barrel the response latency decreased by 1-2 ms. Only the cells responding at short latency exhibited potentiated responses (39% increase) suggesting that some thalamocortical plasticity is still possible at P28-35. These results show that chessboard pattern deprivation is capable of inducing substantial plasticity over a wide area of barrel cortex. All the major forms of plasticity seen with other vibrissa deprivation patterns were present, although no other single deprivation pattern studied so far causes the complete repertoire seen with chessboard deprivation.     

液相BANA试验检测口腔关键厌氧菌方法的建立

目的建立液相苯甲酰精氨酸萘酰胺(简写BANA)水解试验快速检测牙周病关键厌氧菌的新技术。方法利用牙周病相关关键微生物可产生胰蛋白酶样酶使人工合成的酶底物———BANA水解的原理检测这些重要口腔厌氧菌。结果BANA试验可检测出8.0×105以上的牙龈卟啉菌,特异性良好、不受标本采集中血污染的影响;71.88%活动期牙周炎龈下菌斑BANA试验阳性,4%的健康人龈下菌斑BANA试验阳性。结论BANA试验可望成为牙周病诊断新的辅助指标。     

Differential responses of production and respiration to temperature and moisture drive the carbon balance across a climatic gradient in New Mexico

Southwestern North America faces an imminent transition to a warmer, more arid climate, and it is critical to understand how these changes will affect the carbon balance of southwest ecosystems. In order to test our hypothesis that differential responses of production and respiration to temperature and moisture shape the carbon balance across a range of spatio‐temporal scales, we quantified net ecosystem exchange (NEE) of CO₂ and carbon storage across the New Mexico Elevational Gradient, which consists of six eddy‐covariance sites representing biomes ranging from desert to subalpine conifer forest. Within sites, hotter and drier conditions were associated with an increasing advantage of respiration relative to production such that daily carbon uptake peaked at intermediate temperatures – with carbon release often occurring on the hottest days – and increased with soil moisture. Across sites, biotic adaptations modified but did not override the dominant effects of climate. Carbon uptake increased with decreasing temperature and increasing precipitation across the elevational gradient; NEE ranged from a source of ～30 g C m^?2 yr^?1 in the desert grassland to a sink of ～350 g C m^?2 yr^?1 in the subalpine conifer forest. Total aboveground carbon storage increased dramatically with elevation, ranging from 186 g C m^?2 in the desert grassland to 26 600 g C m^?2 in the subalpine conifer forest. These results make sense in the context of global patterns in NEE and biomass storage, and support that increasing temperature and decreasing moisture shift the carbon balance of ecosystems in favor of respiration, such that the potential for ecosystems to sequester and store carbon is reduced under hot and/or dry conditions. This implies that projected climate change will trigger a substantial net release of carbon in these New Mexico ecosystems (～3 Gt CO₂ statewide by the end of the century), thereby acting as a positive feedback to climate change.