A comprehensive overview of the spatial and temporal variability of apple bud dormancy release and blooming phenology in Western Europe

In the current context of global warming, an analysis is required of spatially-extensive and long-term blooming data in fruit trees to make up for insufficient information on regional-scale blooming changes and determinisms that are key to the phenological adaptation of these species. We therefore analysed blooming dates over long periods at climate-contrasted sites in Western Europe, focusing mainly on the Golden Delicious apple that is grown worldwide. On average, blooming advances were more pronounced in northern continental (10 days) than in western oceanic (6–7 days) regions, while the shortest advance was found on the Mediterranean coastline. Temporal trends toward blooming phase shortenings were also observed in continental regions. These regional differences in temporal variability across Western Europe resulted in a decrease in spatial variability, i.e. shorter time intervals between blooming dates in contrasted regions (8–10-day decrease for full bloom between Mediterranean and continental regions). Fitted sequential models were used to reproduce phenological changes. Marked trends toward shorter simulated durations of forcing period (bud growth from dormancy release to blooming) and high positive correlations between these durations and observed blooming dates support the notion that blooming advances and shortenings are mainly due to faster satisfaction of the heating requirement. However, trends toward later dormancy releases were also noted in oceanic and Mediterranean regions. This could tend toward blooming delays and explain the shorter advances in these regions despite similar or greater warming. The regional differences in simulated chilling and forcing periods were consistent with the regional differences in temperature increases.     

Effect of thidiazuron on abscisic acid content in apple bud relative to dormancy

The effect of N -phenyl- N '-1,2,3,-thidiazol-5-ylurea (thidiazuron, Dropp, SN 49537) on abscisic acid (ABA) level in apple ( Malus domestica Borkh. cv. York Imperial) buds associated with bud break and bud development was determined. The data showed that increased ABA content in apple buds was associated with thidiazuron-induced bud break and bud development. ABA stimulated growth of apple buds that had emerged from dormancy by thidiazuron treatment. The ABA in apple buds was confirmed by GC-EIMS and GC-CIMS.     

Long-term temporal changes of plant phenology in the Western Mediterranean

Plants are altering their life cycles in response to current climatic change around the globe. More than 200 000 records for six phenological events (leaf unfolding, flowering, fruit ripening, fruit harvesting, leaf falling and growing season) of 29 perennial species for the period 1943–2003 recorded throughout Spain provide the longest temporal and the broadest spatial assessment of plant phenology changes in the Mediterranean region. The overwhelming majority of the 118 studied phenophases shifted their dates in recent decades. Such changes differed among phenological events. Leaf unfolding, flowering and fruiting are markedly advancing (?0.48, ?0.59 and ?0.32 days yr^?1, respectively), but only since the mid‐1970s. Anemophilous have advanced more days their flowering than entomophilous. However, some species have delayed and others have advanced their leaf falling dates and as a result only a weak shift was observed in this event for the whole of the studied species (+0.12 days yr^?1). The growing season lengthened by 18 days, which implies an increase of 8% in the life of annual leaves. Such an increase was achieved mainly through the advance of leaf unfolding dates in the spring, one of the most productive times of year for vegetation in the Mediterranean. Shifts in the plant calendar were accompanied as well by long‐term changes in the range of onset dates in 39% of studied phenophases. Leaf unfolding, flowering and growing season tended to reduce spatial variability, reflecting a faster and more synchronized onset (or duration) of phenophases across the study area. Changes in spatial variability may aggravate calendar mismatching with other trophic levels resulting from changes in dates. Because temporal responses differed markedly among species, calendar guilds of plants have changed, which suggests alterations of interspecific relationships in plant communities from Mediterranean ecosystems.     

Modelling the spatial and temporal variability of diatoms in the River Murray

We have developed a simple mechanistic model, which simulates the temporaland spatial variability of concentrations of the diatomAulacoseira granulata in the River Murray, NSWAustralia, over large distances under different flow conditions. The modelincorporates a simple growth function determined by the availabilities ofsilica and light, and by temperature. It also includes losses due tosinking and downstream advection. The model is tested against weeklymeasurements for the period 1981-1990, at three sites separated by 1100 km.The seasonal cycle of Aulacoseira concentrations alongthe river is well represented by the model. During times of high flow, theconcentrations of Aulacoseira remain fairly uniformalong the river as the diatoms have insufficient time to grow before beingadvected downstream.     

Net anthropogenic phosphorus inputs: spatial and temporal variability in the Chesapeake Bay region

We estimated net anthropogenic phosphorus inputs (NAPI) in the Chesapeake Bay region. NAPI is an index of phosphorus pollution potential. NAPI was estimated by quantifying all phosphorus inputs and outputs for each county. Inputs include fertilizer applications and non-food phosphorus uses, while trade of food and feed can be an input or an output. The average of 1987, 1992, 1997, and 2002 NAPI for individual counties ranged from 0.02 to 78.46 kg P ha⁻¹ year⁻¹. The overall area-weighted average NAPI for 266 counties in the region was 4.52 kg P ha⁻¹ year⁻¹, indicating a positive net phosphorus input that can accumulate in the landscape or can pollute the water. Large positive NAPI values were associated with agricultural and developed land cover. County area-weighted NAPI increased from 4.43 to 4.94 kg P ha⁻¹ year⁻¹ between 1987 and 1997 but decreased slightly to 4.86 kg P ha⁻¹ year⁻¹ by 2002. Human population density, livestock unit density, and percent row crop land combined to explain 83% of the variability in NAPI among counties. Around 10% of total NAPI entering the Chesapeake Bay watershed is discharged into Chesapeake Bay. The developed land component of NAPI had a strong direct correlation with measured phosphorus discharges from major rivers draining to the Bay (R ² = 0.81), however, the correlation with the simple percentage of developed land was equally strong. Our results help identify the sources of P in the landscape and evaluate the utility of NAPI as a predictor of water quality.     

A brief overview on the status and prospects of sturgeon farming in Western and Central Europe

This paper provides a short overview on the status of sturgeon farming in Europe, covering most of the EU and former East Block countries. Production trends are presented along with a listing of species cultured in various countries. Principle culture systems are described and an opinion is presented on possible constraints and perspectives of sturgeon farming, including market opportunities.     

Implications of temporal and spatial variability in Paracentrotus lividus populations to the associated commercial coastal fishery

Analysis of population structure and behaviour of a semi-enclosed and theoretically non-fished population of the echinoid Paracentrotus lividus at Lough Hyne marine nature reserve, Co. Cork, Ireland, showed distinct variability. Aspects of the behavioural variability in this species have significant consequences for the natural fishery harvest potential of this species. Whether or not, when and where individuals migrate to the upper surfaces of rocks varies on a local and regional scale as well as seasonally. The effect of this is apparent changes in (a) the population structure, (b) the population size and (c) the population centres of abundance. The population structure and size of the Lough Hyne population has changed substantially, as have those on a larger spatial scale, although the causative agents are debatable. Such changes are the result of large-scale mortality of adults and failure of cohort recruitment. Despite the undeniable pressures of overfishing at many localities, it seems likely there is a strong `natural' and possibly predictable element to the variability in P. lividus population size and structure. For the restoration and sustainable harvest of Irish P. lividus aspects of its behavioural ecology need to be taken more closely into consideration.     

Characterising the temporal variability of the spatial distribution of animals: an application to seabirds at sea

Understanding the patterns of spatial and temporal variations in animal abundance is a fundamental question in ecology. Here, we propose a method to quantify temporal variations in animal spatial patterns and to determine the spatial scale at which such temporal variability is expressed. The methodology extends from the approach proposed by Taylor (Taylor, L. R. 1961. Aggregation, variance and the mean. Nature 189: 732–735) and relies on models of the relationship between temporal mean and variance in animal abundance. Repeated observations of the spatial distribution of populations are used to construct spatially explicit models of Taylor's power law. The resulting slope parameters of the Taylor power law provide local measures of the temporal variability in animal abundance. We investigate if the value of the slope varies significantly with spatial location and with spatial scale. The method is applied to seabirds distribution in the Bay of Biscay. We study four taxa (northern gannets, large gulls, auks and kittiwakes) that display distinct geographical distribution, spatial structure and foraging strategy. Our results show that the temporal variability associated to the spatial distribution of northern gannets is high and spatially homogeneous. By contrast, kittiwakes present large geographical areas associated with high and low variability. The temporal variability of auk's spatial distribution is strongly scale-dependent: at fine scale high variability is associated to high abundance, but at large scale high variability is associated to the external border of their distribution range. The method provides satisfactory results and useful information on species spatio-temporal distribution.     

Weak spatial and temporal population genetic structure in the rosy apple aphid, Dysaphis plantaginea, in French apple orchards

We used eight microsatellite loci and a set of 20 aphid samples to investigate the spatial and temporal genetic structure of rosy apple aphid populations from 13 apple orchards situated in four different regions in France. Genetic variability was very similar between orchard populations and between winged populations collected before sexual reproduction in the fall and populations collected from colonies in the spring. A very small proportion of individuals (～2%) had identical multilocus genotypes. Genetic differentiation between orchards was low (F(ST)<0.026), with significant differentiation observed only between orchards from different regions, but no isolation by distance was detected. These results are consistent with high levels of genetic mixing in holocyclic Dysaphis plantaginae populations (host alternation through migration and sexual reproduction). These findings concerning the adaptation of the rosy apple aphid have potential consequences for pest management.     

Dietary variability in fishes: the roles of taxonomic, spatial, temporal and ontogenetic factors

In spite of the general use of diet data in ecological research, still very little is known about the relative roles of spatial, temporal and biotic (e.g. taxonomic identity, size, sex) factors in dietary variability of fishes. Here, we applied canonical correspondence analysis and variation partitioning to examine the roles of taxonomic, annual, seasonal, lake basin, habitat and ontogenetic (standard length, L _S) factors in the dietary variation of fishes in large and shallow Lake Balaton, Hungary. The analyses were performed at the assemblage (15 fish species) and the individual species levels, and based on high (24 fine resource categories) and low resolution (nine broad resource categories) diet data. As hypothesised, most of the explained variation related to interspecific differences, while the roles of sampling year, season, lake area, habitat and L _S proved to be unexpectedly low at the assemblage level. In addition, no regularity was found in how the relative roles of these factors change between fish species. The high ratio of the unexplained variation suggests that individual variations in foraging strategies and resource use of fishes and unascertained stochastic processes had a strong influence on dietary variability both at the assemblage and the individual species levels.     

Ultrastructural changes in the endoplasmic reticulum during dormancy release of apple embryos (Pyrus malus L.)

Apple embryos were treated by cold (0°C) within the fruits, to break their dormancy; the controls were treated at 12°C or at 20°C. Ultrastructural features of meristematic cells in the embryonic axis were compared for each treatment. The organization of the cells of dormant embryos was described: Endoplasmic reticulum consisted in some short rough cisternae; lipid droplets regularly arranged near the plasmalemma constituted a kind of shell; mitochondria had a few cristae; and dictyosomes were rarely observed. All these features are typical of dry seeds. After cold treatments, the only evolution observed was in the endoplasmic reticulum, where highly organized stacks appeared progressively as a function of time at 0°C. An intermediate temperature (12°C) induced similar formations in the reticulum but they were rarely observed and their degree of organization was lower than that obtained at 0°C. At 20°C, endoplasmic reticulum resembled that of the dormant embryo cells. The relation between the appearance of these structures in the reticulum and the disappearance of dormancy induced by cold is discussed.Abbreviations ER endoplasmic reticulum - RER rough endoplasmic reticulum     

A holistic approach to study the temporal variability in gait

Movement variability has become an important field of research and has been studied to gain a better understanding of the neuro-muscular control of human movements. In addition to studies investigating "amplitude variability" there are a growing number of studies assessing the "temporal variability" in movements by applying non-linear analysis techniques. One limitation of the studies available to date is that they quantify variability features in specific, pre-selected biomechanical or physiological variables. In many cases it remains unclear if and to what degree these pre-selected variables quantify characteristics of the whole body movement. This technical note proposes to combine two analysis techniques that have already been applied for gait analysis in order to quantify variability features in walking with variables whose significance for the whole movements are known. Gait patterns were recorded using a full-body marker set on the subjects whose movements were captured with a standard motion tracing system. For each time frame the coordinates of all markers were interpreted as a high-dimensional "posture vector". A principal component analysis (PCA) conducted on these posture vectors identified the main one-dimensional movement components of walking. Temporal variability of gait was then quantified by calculating the maximum Lyapunov Exponent (LyE) of these main movement components. The effectiveness of this approach was demonstrated by determining differences in temporal variability between walking in unstable shoes and walking in a normal athletic-type control shoe. Several additional conceptual and practical advantages of this combination of analysis methods were discussed.     

Polychaetes associated with the sciaphilic alga community in the northern Aegean Sea: spatial and temporal variability

Polychaete biodiversity has received little attention despite its importance in biomonitoring. This study describes polychaete diversity, and its spatial and temporal variability in infralittoral, hard substrate assemblages. Seven stations were chosen in the central area of the northern Aegean Sea. At each station, one to three depth levels were set (15, 30 and 40 m). Five replicates were collected by scuba diving with a quadrat sampler (400 cm²) from each station and depth level during summer for the spatial analysis, and seasonally for the study of temporal changes. Common biocoenotic methods were employed (estimation of numerical abundance, mean dominance, frequency, Margalefs richness, Shannon-Weaver index and Pielous evenness). A total of 5,494 individuals, belonging to 79 species, were counted and classified. Diversity indices were always high. Clustering and multidimensional scaling techniques indicated a high heterogeneity of the stations, although these were all characterized by the sciaphilic alga community. A clear seasonal pattern was not detectable. Summer and autumn samples discriminate, while winter and spring form an even group. The abundance/biomass comparison indicated a dominance of k-strategy patterns, characteristic of stable communities.Communicated by H.-D. Franke     

The emergence of automated high-frequency flow cytometry: revealing temporal and spatial phytoplankton variability

Phytoplankton observation is the product of a number of trade-offsrelated to sampling processes, required level of diversity andsize spectrum analysis capabilities of the techniques involved.Instruments combining the morphological and high-frequency analysisfor phytoplankton cells are now available. This paper presentsan application of the automated high-resolution flow cytometerCytosub as a tool for analysing phytoplanktonic cells in theirnatural environment. High resolution data from a temporal studyin the Bay of Marseille (analysis every 30 min over 1 month)and a spatial study in the Southern Indian Ocean (analysis every5 min at 10 knots over 5 days) are presented to illustrate thecapabilities and limitations of the instrument. Automated high-frequencyflow cytometry revealed the spatial and temporal variabilityof phytoplankton in the size range 1–50 µm thatcould not be resolved otherwise. Due to some limitations (instrumentalmemory, volume analysed per sample), recorded counts could bestatistically too low. By combining high-frequency consecutivesamples, it is possible to decrease the counting error, followingPoisson’s law, and to retain the main features of phytoplanktonvariability. With this technique, the analysis of phytoplanktonvariability combines adequate sampling frequency and effectivemonitoring of community changes.