Effects of microhabitat characteristics on the settlement and recruitment of a coral reef fish at two spatial scales

Populations of fishes on coral reefs are replenished by the settlement of pelagic larvae to demersal populations. Recruitment varies spatially and temporally and can exert strong effects on the dynamics of reef fish populations. This study examined the effect of microhabitat characteristics on small-scale and large-scale recruitment variation in the three-spot damselfish, Stegastes planifrons (Cuvier). Comparison of 0.25-m² quadrats occupied by three-spots with randomly sampled null quadrats showed that three-spots quadrats contained a higher percent cover of the coral Montastrea annularis than would be expected at random. Manipulative experiments on three types of 1.0-m² patch reefs (living M. annularis, dead Porites Porites and dead Acropora palmata) patch reefs on showed that this non-random distribution was established by microhabitat choice during settlement and not by differential post-settlement survival. The presence of conspecific juveniles did not affect settlement. Recruitment was monitored at nine sites on three islands over 3 years. Recruitment showed no consistent pattern in the relative levels of recruitment among sites. Similarly, no consistent relationship emerged between recruitment levels and microhabitat characteristics at the nine sites. For example, at this large scale, the percent cover of M. annularis explained variation in recruitment in only 1 out of 3 years. These results suggest that small-scale recruitment patterns are influenced by microhabitat choice during settlement, but that these habitat effects do not scale up to influence large-scale variation in recruitment.     

Characterising the phytophagous arthropod fauna of a single host plant species: assessing survey completeness at continental and local scales

Quantifying survey completeness is a key step in designing and interpreting biodiversity assessments. To date this has only been examined either at a local scale through repetitive sampling, or across broader geographic areas through multiple survey sites. In this paper, we determine the completeness of sampling at both local and continental scales, of the phytophagous arthropod assemblage on the Neotropical shrub Parkinsonia aculeata (Leguminosae). We used survey gap analysis (SGA) to determine whether existing surveys adequately sampled the diversity of environments and geographic space covered by the plant. Within defined geographic regions, we determined survey completeness at a local scale with species accumulation curves. SGA identified the highest priority sites for future sampling in the Sonoran Desert and the Pacific Coast of South America. The arthropods sampled on P. aculeata differed significantly between seasons, highlighting the importance of including surveys throughout the year. At the local scale, surveys in most regions were estimated to have sampled <50 % of all species. Only the Mexican Gulf, following 84 samples including 902 individuals, had a reasonably complete sample of all species (more than 50 %). As in other studies, rare species will continue to be detected even after extensive surveying, and it is likely that close to 100 samples or 1,000 individuals will be needed to attain 50 % survey completeness in a region. However, if the objective is to document close “host-associations” then effort may be better directed at surveying ecologically distinct new areas rather than exhaustive sampling in existing ones. Methods such as SGA can direct such surveys, and in conjunction with species-richness estimates, can be used to assess the adequacy of existing surveys.     

Population genetic structure of three freshwater mussel (Unionidae) species within a small stream system: significant variation at local spatial scales

1. Unionid mussels are highly threatened, but little is known about genetic structure in populations of these organisms. We used allozyme electrophoresis to examine partitioning of genetic variation in three locally abundant and widely distributed species of mussels from a catchment in Ohio. 2. Within‐population variation was similar to that previously reported for freshwater mussels, but genotype frequencies exhibited heterozygote deficiencies in many instances. All three species exhibited significant among‐population variation. Evidence of isolation‐by‐distance was found in Elliptio dilatata and Ptychobranchus fasciolaris, while Lampsilis siliquoidea showed no geographical pattern of among‐population variation. 3. Our results suggest that the isolating effects of genetic drift were greater in L. siliquoidea than in the other species. Differentiation of populations occurred at a much smaller spatial scale than has previously been found in freshwater mussels. Differences among species may reflect differences in the dispersal abilities of fishes that serve as hosts for the glochidia larvae of mussels. 4. Based on our results, we hypothesise that species of mussels that are common to large rivers exhibit relatively large amounts of within‐population genetic variation and little differentiation over large geographical distances. Conversely, species typical of small streams show lower within‐population genetic variation and populations will be more isolated. If this hypothesis can be supported, it may prove useful in the design of conservation strategies that maintain the genetic structure of target species.     

The impact of local surface changes in Borneo on atmospheric composition at wider spatial scales: coastal processes, land-use change and air quality

We present results from the OP3 campaign in Sabah during 2008 that allow us to study the impact of local emission changes over Borneo on atmospheric composition at the regional and wider scale. OP3 constituent data provide an important constraint on model performance. Treatment of boundary layer processes is highlighted as an important area of model uncertainty. Model studies of land-use change confirm earlier work, indicating that further changes to intensive oil palm agriculture in South East Asia, and the tropics in general, could have important impacts on air quality, with the biggest factor being the concomitant changes in NO(x) emissions. With the model scenarios used here, local increases in ozone of around 50 per cent could occur. We also report measurements of short-lived brominated compounds around Sabah suggesting that oceanic (and, especially, coastal) emission sources dominate locally. The concentration of bromine in short-lived halocarbons measured at the surface during OP3 amounted to about 7 ppt, setting an upper limit on the amount of these species that can reach the lower stratosphere.     

Performance of a clonal species in patchy environments: effects of environmental context on yield at local and whole-plant scales

Yield of the clonal plant Glechoma hederacea was compared at different spatial scales, in heterogeneous and homogeneous environments providing the same amount of nutrients. For the heterogeneous treatments, environments were created with different patch sizes and different degrees of contrast in nutrient concentration between patches of different quality. Total clone yield differed by almost 2.5-fold across treatments, being highest in environments with large patches and high contrast, lowest in environments with small patches and high contrast, and intermediate under homogeneous conditions. Compared with plants in homogeneous conditions, there were significant increases or decreases in yield at all scales of measurement in many of the heterogeneous treatments. These effects on yield reflected a combination of local responses to growing conditions and modification of these responses due to physiological integration with other parts of the plant growing in contrasting conditions, supporting the proposal of de Kroon et al. (2005 New Phytol 166:73–82). The results show that plant yield at all scales is strongly dependent on environmental context, and that maximum yield can only be realized under a limited range of heterogeneous conditions.     

rpoB-PCR amplified gene and temporal temperature gradient gel electrophoresis: a rapid tool to analyse bacterial strains representative of cold-smoked salmon microflora

AIM: To evaluate rpoB gene as a biomarker of microbial biodiversity associated to cold-smoked salmon by a novel nested-polymerase chain reaction/temporal temperature gradient gel electrophoresis (PCR/TTGE) technique applied on pure cultures of reference strains. METHODS AND RESULTS: DNA obtained from pure cultures of reference strains was used in a succession of a first PCR amplification of rpoB fragment with degenerated nonclamped primers and a nested-PCR with nondegenerated clamped primers. PCR products were then applied on a TTGE gel in order to analyse strains profile. High quantity of nested-PCR products were obtained for each tested strain and TTGE profiles showed a good separation between the different reference bacteria and an easy way to associate one band to one species. CONCLUSION: The nested-PCR/TTGE technique used in this study is a promising way of investigating bacterial community structure of cold-smoked salmon or other food matrix. SIGNIFICANCE AND IMPACT OF THE STUDY: Because of its single copy state leading to single band profiles in TTGE, rpoB constitute a good potential molecular marker for further development of cold-smoked salmon biodiversity analysis.     

Prompt chlorophyll fluorescence as a tool for crop phenotyping: an example of barley landraces exposed to various abiotic stress factors

The study examined photosynthetic efficiency of two barley landraces (cvs. Arabi Abiad and Arabi Aswad) through a prompt fluorescence technique under influence of 14 different abiotic stress factors. The difference in the behavior of photosynthetic parameters under the same stress factor in–between cv. Arabi Abiad and cv. Arabi Aswad indicated different mechanisms of tolerance and strategies for the conversion of light energy into chemical energy for both the landraces. This study confirmed the suitability of some chlorophyll fluorescence parameters as reliable biomarkers for screening the plants at the level of photosynthetic apparatus.     

Impact of landscape pattern at multiple spatial scales on water quality: A case study in a typical urbanised watershed in China

Buffer zones along rivers and streams can provide water quality services by filtering nutrients, sediment and other contaminants from the surface. Redundancy analysis was used to determine the influence of the landscape pattern at the entire catchment scale and at multiple buffer zone scales (100 m, 300 m, 500 m, 1000 m and 1500 m) on the water quality in a highly urbanised watershed. Change-point analysis was further applied to estimate the specific locations along a gradient of landscape metric that result in a sudden change in the water quality variable. The landscape characteristics for 100 m buffer zones appeared to have a slightly greater influence on the water quality than the entire catchment. The patch density of urban land and the large patch index of water were recognised as the dominant variables influencing the water quality for a 100 m buffer zone. The result of change-point analysis indicated key interval values of the two landscape metrics within the 100 m buffer zone. When the patch density of urban land was >30–40 n/100 ha and the largest patch index of water was >2.5–3.5%, the watershed water quality appeared to be better protected.     

Statistical models of invertebrate distribution on Macquarie Island: a tool to assess climate change and local human impacts

Sub-Antarctic islands are good model systems in which to study the ecological effects of human impacts, particularly global climate change and alien species. Invertebrates form a central component of these ecosystems. We conducted a stratified survey of 69 sites on sub-Antarctic Macquarie Island and used logistic regression models to describe the distribution of 14 abundant invertebrate species. We also developed a statistical model of windspeed based on topography. The distributions of individual species were described by different combinations of aspect, altitude and vegetation type. Ordination of sites based on species composition showed strong effects of altitude and vegetation on invertebrate assemblages. The species distribution models provide a tool for detecting, monitoring and predicting effects of climate change and alien species on biota and ecosystem processes. Accepted: 30 August 1998     

Phase shift to algal dominated communities at mesophotic depths associated with lionfish (<Emphasis Type="Italic">Pterois volitans</Emphasis>) invasion on a Bahamian coral reef

Mesophotic coral reefs (30–150 m) have been assumed to be physically and biologically connected to their shallow-water counterparts, and thus may serve as refugia for important taxonomic groups such as corals, sponges, and fish. The recent invasion of the Indo–Pacific lionfish (Pterois volitans) onto shallow reefs of the Caribbean and Bahamas has had significant, negative, effects on shallow coral reef fish populations. In the Bahamas, lionfish have extended their habitat range into mesophotic depths down to 91 m where they have reduced the diversity of several important fish guilds, including herbivores. A phase shift to an algal dominated (>50% benthic cover) community occurred simultaneously with the loss of herbivores to a depth of 61 m and caused a significant decline in corals and sponges at mesophotic depths. The effects of this invasive lionfish on mesophotic coral reefs and the subsequent changes in benthic community structure could not be explained by coral bleaching, overfishing, hurricanes, or disease independently or in combination. The significant ecological effects of the lionfish invasion into mesophotic depths of coral reefs casts doubt on whether these communities have the resilience to recover themselves or contribute to the recovery of their shallow water counterparts as refugia for key coral reef taxa.     

Patterns of genetic variability and habitat occupancy in Crepis triasii (Asteraceae) at different spatial scales: insights on evolutionary processes leading to diversification in continental islands

Background and Aims

Archipelagos are unique systems for studying evolutionary processes promoting diversification and speciation. The islands of the Mediterranean basin are major areas of plant richness, including a high proportion of narrow endemics. Many endemic plants are currently found in rocky habitats, showing varying patterns of habitat occupancy at different spatial scales throughout their range. The aim of the present study was to understand the impact of varying patterns of population distribution on genetic diversity and structure to shed light on demographic and evolutionary processes leading to population diversification in Crepis triasii, an endemic plant from the eastern Balearic Islands.

Methods

Using allozyme and chloroplast markers, we related patterns of genetic structure and diversity to those of habitat occupancy at a regional (between islands and among populations within islands) and landscape (population size and connectivity) scale.

Key Results

Genetic diversity was highly structured both at the regional and at the landscape level, and was positively correlated with population connectivity in the landscape. Populations located in small isolated mountains and coastal areas, with restricted patterns of regional occupancy, were genetically less diverse and much more differentiated. In addition, more isolated populations had stronger fine-scale genetic structure than well-connected ones. Changes in habitat availability and quality arising from marine transgressions during the Quaternary, as well as progressive fragmentation associated with the aridification of the climate since the last glaciation, are the most plausible factors leading to the observed patterns of genetic diversity and structure.

Conclusions

Our results emphasize the importance of gene flow in preventing genetic erosion and maintaining the evolutionary potential of populations. They also agree with recent studies highlighting the importance of restricted gene flow and genetic drift as drivers of plant evolution in Mediterranean continental islands.     

Calcium effects on life-history traits in a wild population of the great tit (Parus major): analysis of long-term data at several spatial scales

Calcium is an essential micronutrient for birds during egg formation and for skeletal development in nestlings. Habitat level studies suggest that birds breeding in low-calcium areas may be limited in the size or number of eggs they lay and in the quality of their nestlings. However, as birds forage non-randomly and may travel considerable distances to acquire calcium, describing different breeding environments in terms of their calcium availability is problematic. Here we explore the spatial relationships between 300-fold variation in soil calcium and the life-history traits of ca. 6,000 pairs of great tits breeding in a single continuous woodland over 41 years. Controlling for other habitat differences, we found strong positive associations between soil calcium, clutch size and recruitment at spatial scales of over 300 m from each nestbox, suggesting that females may have been travelling inter-territorially to acquire calcium during egg formation. Soil calcium near each nestbox (mean distance = 58 m) was a strong positive predictor of mean fledgling mass, suggesting that local calcium was more important during nestling stages. We found no effect of soil calcium on lay-date or egg mass. This study is the first to provide evidence that small woodland passerines are limited by calcium availability at several different spatial scales. However, experimental work is necessary to test the causality of these spatial patterns.     

Use of local anaesthetics and adjuncts for spinal and epidural anaesthesia and analgesia at German and Austrian University Hospitals: an online survey to assess current standard practice

Background

The present anonymous multicenter online survey was conducted to evaluate the application of regional anaesthesia techniques as well as the used local anaesthetics and adjuncts at German and Austrian university hospitals.

Methods

39 university hospitals were requested to fill in an online questionnaire, to determine the kind of regional anaesthesia and preferred drugs in urology, obstetrics and gynaecology.

Results

33 hospitals responded. No regional anaesthesia is conducted in 47% of the minor gynaecological and 44% of the urological operations; plain bupivacaine 0.5% is used in 38% and 47% respectively. In transurethral resections of the prostate and bladder no regional anaesthesia is used in 3% of the responding hospitals, whereas plain bupivacaine 0.5% is used in more than 90%. Regional anaesthesia is only used in selected major gynaecological and urological operations. On the contrary to the smaller operations, the survey revealed a large variety of used drugs and mixtures. Almost 80% prefer plain bupivacaine or ropivacaine 0.5% in spinal anaesthesia in caesarean section. Similarly to the use of drugs in major urological and gynaecological operations a wide range of drugs and adjuncts is used in epidural anaesthesia in caesarean section and spontaneous delivery.

Conclusions

Our results indicate a certain agreement in short operations in spinal anaesthesia. By contrast, a large variety concerning the anaesthesiological approach in larger operations as well as in epidural analgesia in obstetrics could be revealed, the causes of which are assumed to be primarily rooted in particular departmental structures.     

Seasonal changes in food consumption and growth of Arctic charr exposed to either simulated natural or a 12:12 LD photoperiod at constant water temperature

Immature male and female and maturing male Arctic charr Salvelinus alpinus were held at constant temperature (4° C) under either simulated natural photoperiod (nLD) or constant photoperiod (12:12 LD) conditions, and feed intake and growth were monitored at monthly intervals over 13 months. Food was supplied in excess during a 5-h period each day, and daily consumption was determined using X-radiography. Food consumption and growth of both immature and maturing fish showed distinct seasonal cycles irrespective of photoperiod treatment. Feed intake and growth rates were highest in mid-summer and lowest in autumn. The fact that seasonal cycles persisted under constant photoperiod (12:12 LD) and temperature conditions suggests that circannual rhythms of food consumption and growth exist in the absence of seasonal changes in these environmental cues. The data support the view that seasonal changes in food consumption and growth in the Arctic charr are driven by endogenous rhythms. Reductions in feeding and growth in autumn occurred about 1 month earlier in the maturing males than in the immature fish. Males that matured under the 12:12 LD regime displayed a growth cycle that was delayed in comparison with that shown by the maturing males held under nLD.     

Cavity hydration as a gateway to unfolding: an NMR study of hen lysozyme at high pressure and low temperature

We have used low temperatures (down to − 20 °C) and high pressures (up to 2000 bar) to populate low-lying excited state conformers of hen lysozyme, and have analyzed their structures site-specifically using ¹⁵N/¹H two-dimensional HSQC NMR spectroscopy. The resonances of a number of residues were found to be selectively broadened, as the temperature was lowered at a pressure of 2000 bar. The resulting disappearance of cross-peaks includes those of residues in the β-domain of the protein and the cleft between the β- and α-domains, both located close to water-containing cavities. The results indicate that low-lying excited state conformers of hen lysozyme are characterized by slowly fluctuating local conformations around these cavities, attributed to the opportunities for water molecules to penetrate into the cavities. Furthermore, we have found that these water-containing cavities are conserved in similar positions in lysozymes from a range of different biological species, indicating that they are a common evolutionary feature of this family of enzymes.     

Biphenyl bicelle disks align perpendicular to magnetic fields on large temperature scales: a study combining synthesis, solid-state NMR, TEM, and SAXS

A phosphatidylcholine lipid (PC) containing a biphenyl group in one of its acyl chains (1-tetradecanoyl-2-(4-(4-biphenyl)butanoyl)-sn-glycero-3-PC, TBBPC) was successfully synthesized with high yield. Water mixtures of TBBPC with a short-chain C(6) lipid, dicaproyl-PC (DCPC), lead to bicelle systems formation. Freeze-fracture electron microscopy evidenced the presence of flat bilayered disks of 800 A diameter for adequate composition, hydration, and temperature conditions. Because of the presence of the biphenyl group, which confers to the molecule a positive magnetic anisotropy Delta chi, the disks align with their normal, n, parallel to the magnetic field B(0), as directly detected by (31)P, (14)N, (2)H solid-state NMR and also using small-angle x-ray scattering after annealing in the field. Temperature-composition and temperature-hydration diagrams were established. Domains where disks of TBBPC/DCPC align with their normal parallel to the field were compared to chain-saturated lipid bicelles made of DMPC(dimyristoylPC)/DCPC, which orient with their normal perpendicular to B(0). TBBPC/DCPC bicelles exist on a narrow range of long- versus short-chain lipid ratios (3%) but over a large temperature span around room temperature (10-75 degrees C), whereas DMPC/DCPC bicelles exhibit the reverse situation, i.e., large compositional range (22%) and narrow temperature span (25-45 degrees C). The two types of bicelles present orienting properties up to 95% dilution but with the peculiarity that water trapped in biphenyl bicelles exhibits ordering properties twice as large as those observed in the saturated-chains analog, which offers very interesting properties for structural studies on hydrophilic or hydrophobic embedded biomolecules.     

Large temperature plunges recorded by data loggers at different depths on an Indian Ocean atoll: comparison with satellite data and relevance to coral refuges

Seawater temperature was recorded at two-hourly intervals for two years (March 2006-March 2008) by six data loggers in Diego Garcia atoll, central Indian Ocean. Loggers were substrate mounted, in two transects of 5, 15 and 25 m depth on a seaward reef and in a lagoonal pass. During the season of mixed but predominantly northwest winds, regular plunges of temperature of 5–7°C occurred with a periodicity of 1–4 days. This partly coincided with the period of greatest annual warming. Temperature fluctuations increased with increasing depth. Temperature traces are compared with HadISST1 and AVHRR satellite-derived temperature data which do not capture the deeper water temperature plunges. Reasons for the regular temperature plunges appear to include both tidal cycles and unidentified, internal waves. This is important for issues of coral refuges, complicating use of satellite-derived temperature data for planning optimal coral reef conservation areas.