On the behaviour of the residence time at the bottom of the mixed layer

To understand why the findings of Deleersnijder et al. [(2006), Environ Fluid Mech 6: 25–42]—the residence time in the mixed layer in not necessarily zero at the pycnocline—are consistent with those of Delhez and Deleersnijder [(2006), Ocean Dyn 56:139–150]—the residence time in a control domain vanishes at the open boundaries of this control domain—, it is necessary to consider a control domain that includes part of the pycnocline, in which the eddy diffusivity is assumed to be zero. Then, depending on the behaviour of the eddy diffusivity near the bottom of the mixed layer, the residence time may be seen to exhibit a discontinuity at the interface between the mixed layer and the pycnocline. If such a discontinuity exists, the residence time is non-zero in the former and zero in the latter. This is illustrated by analytical solutions obtained under the assumption that the eddy diffusivity is constant in the mixed layer.     

Observations on the function of the glands of the foot of the pediveliger of Ostrea edulis during settlement

The use during settlement of secretions of the 9 different types of gland in the foot of the pediveliger of Ostrea edulis L. was examined experimentally. During settlement, there is a progressive decrease in the crawling speed of the larva and a strengthening of its bond with the substratum. Both changes are related to (a) a change from ciliary to muscular pedal locomotion; (b) the increasing acidity and viscosity of the mucoid secretions used; (c) the secretion of a byssus thread by the glands of the byssus duet; (d) changes in the form and composition of this byssus. At the termination of settlement, the entire contents of 2 types of gland are discharged. Their secretions give rise to the cement which permanently fixes the larva to the substratum. The 9 types of gland are utilised sequentially in a manner closely related to the 6 phases recognised in settlement behaviour.     

Modelling the interactions between nutrients and the submersed vegetation in the Orbetello Lagoon

The main problem in the Orbetello Lagoon is the control of the submersed vegetation, both in biomass and inventory, to manage a problematical coexistence between macroalgae and macrophytes. While macroalgae are liable to cause dystrophic crises, macrophytes oxygenate and stabilise the sediment and thus control the nutrient flux into the water. A mathematical model was required by the Orbetello Lagoon Managerial Office to predict the development of both groups and test the actions to favour macrophytes over macroalgae, in the context of a decision support system. This model, developed for this need, takes into account the interactions between nutrients and the submersed vegetation in a 2D spatial context including a hydrodynamic model for the water movements and an ecological model describing the interactions between nutrients and the submersed vegetation. In the spatial grid the model operates with two interlocked modules: each cell implements the kinetics of nutrients, vegetation and their interactions, running on an hourly basis to keep track of the circadian cycles, whereas an advection/diffusion mechanism running on a daily basis exchanges information among all the grid cells. The model output consists of daily variations in nutrient concentrations and vegetation biomass showing the relative abundance of either group as a consequence of environmental conditions. After a sensitivity assessment, the model has been calibrated with data from the Orbetello Lagoon, where it can now be used as a forecasting tool to predict the development of vegetation and the relative advantage that macrophytes may have upon macroalgae.     

Conservation and the Lure of the Garden

Abstract:  Among the conservation voices today who seek a sensible "middle ground" in remedying land-use problems are those who propose a tend-the-garden ethic in which humans would merely need to view the earth as a garden and labor to make it productive and beautiful in order to solve conservation challenges. This line of reasoning is exemplified by Michael Pollan's highly praised book, Second Nature , which supports conservation values but harshly criticizes contemporary environmental efforts, including the work of such organizations as The Nature Conservancy. Pollan's portrayal of the gardener as model conservationist is usefully compared with an important essay by Aldo Leopold from a half-century ago, "The Farmer as a Conservationist," which similarly uses a model land tender as exemplar of where conservation needs to head. Comparing the two writings reveals profound flaws in the contemporary tend-the-garden line of thought. In doing so, it usefully reveals to scientists why their efforts are so often misunderstood and resisted. The popularity of tend-the-garden reasoning illustrates how successful the environmental backlash has been in misportraying the motives and aims of serious conservationists, particularly those who seek to protect wildlife and natural habitat. In doing so, it highlights the need for conservationists to take their own ideas more seriously and to do a far better job of presenting those ideas, in coherent form, to broad audiences.     

Splitting the tail of the displacement kernel shows the unimportance of kurtosis

Animals disperse in space through different movement behaviors, resulting in different displacement distances. This is often described with a displacement kernel where the long-distance dispersers are within the tail of the kernel. A displacement with a large proportion of long-distance dispersers may have impact on different aspects of spatial ecology such as invasion speed, population persistence, and distribution. It is, however, unclear whether the kurtosis of the kernel plays a major role since a fatter tail also influences the variance of the kernel. We modeled displacement in landscapes with different amounts and configurations of habitats and handled kurtosis and variance separately to study how these affected population distribution and transition time. We conclude that kurtosis is not important for any of these aspects of spatial ecology. The variance of the kernel, on the other hand, was of great importance to both population distribution and transition time. We argue that separating variance and kurtosis can cast new light on the way in which long-distance dispersers are important in ecological processes. Consequences for empirical studies are discussed.     

刍议医院资产管理的现状及其对策

医院的固定资产和流动资产是医院赖以生存和发展的基础,是一项非经营性国有资产．目前公立医院固定资产、流动资产管理现状不容乐观,针对这种状况,首先分析问题形成的原因,然后提出管理的措施或建议,从而使资产管理工作规范化、制度化、科学化,使有限的卫生资源发挥出最大的社会效益和经济效益．参3．     

Assessing the relation between the distribution of salt-marsh communities and the sediment budget of the North Norfolk coast

Very high resolution imagery from an airborne multi-spectrål scanner has been used to estimate the distribution of different salt-marsh communities along a 30-km stretch of the North Norfolk coast. Field observations have been used to develop a mathematical relationship between the vegetation, physical environment and sediment accumulation. This relationship has been used to produce provisional sediment accretion maps for the north Norfolk coast.     

On the functional extinction of the Passenger Pigeon

The Passenger Pigeon (Ectopistes migratorius) was a social breeder, and it has been suggested that the species experienced functional extinction, defined as a total reproductive failure, prior to its actual extinction in the early years of the 20th century. We applied a novel randomization test based on the relative times of the most recent egg‐ and skin‐specimen sightings (i.e., recorded date of specimen collection) to test for functional extinction. For a total of 6 eggs and 27 skins, the observed significance level was 0.38, which indicated that the species did not become functionally extinct. Thus, proposals to reverse its rapid decline in the late 19th century could have been successful.     

On the modelling of the process of land application of sludge in the Mediterranean region

Based on a critical evaluation of a large number of published studies, a systematic Modelling of Actions of Land Application of Sludge (MALAS) for agricultural use is presented.

This paper deals with the presentation of the (MALAS) as a 14‐step procedure, in the form of flow chart to facilitate a simple and computerized solution for the particular case involved.

The lack of knowledge and education concerning the benefits of land application as well as the lack of past experience are two significance drawbacks for public and local fanners acceptance. It is within the duties of our countries to face this crucial problem by providing the public with the required information.     

Bioluminescence in the high Arctic during the polar night

This study examines the composition and activity of the planktonic community during the polar night in the high Arctic Kongsfjord, Svalbard. Our results are the first published evidence of bioluminescence among zooplankton during the Arctic polar night. The observations were collected by a bathyphotometer detecting bioluminescence, integrated into an autonomous underwater vehicle, to determine the concentration and intensity of bioluminescent flashes as a function of time of day and depth. To further understand community dynamics and composition, plankton nets were used to collect organisms passing through the bathyphotometer along with traditional vertical net tows. Additionally, using a moored bathyphotometer closed to the sampling site, the bioluminescence potential itself was shown not to have a diurnal or circadian rhythm. Rather, our results provide evidence for a diel vertical migration of bioluminescent zooplankton that does not correspond to any externally detectable changes in illumination.     

Estimate of the Area Affected Ecologically by the Road System in the United States

Abstract: In view of an extensive road system, abundant and rapidly growing vehicular traffic, and a scattered literature indicating that some ecological effects of roads extend outward for > 100 m, it seems likely that the cumulative ecological effect of the road system in the United States is considerable. Two recent studies in The Netherlands and Massachusetts ( U.S.A.) evaluated several ecological effects of roads, including traffic noise effects, and provide quantitative evidence for a definable "road-effect zone." Based on the approximate width of this asymmetric convoluted zone, I estimate that about one-fifth of the U.S. land area is directly affected ecologically by the system of public roads. I identify a series of assumptions and variables suggesting that over time this preliminary estimate is more likely to rise than drop. Several transportation planning and policy recommendations, ranging from perforating the road barrier for wildlife crossings to closing certain roads, offer promise for reducing this enormous ecological effect.     

Estimating the spatial covariance structure using the geoadditive model

In geostatistics, both kriging and smoothing splines are commonly used to generate an interpolated map of a quantity of interest. The geoadditive model proposed by Kammann and Wand (J R Stat Soc: Ser C (Appl Stat) 52(1):1–18, 2003) represents a fusion of kriging and penalized spline additive models. Complex data issues, including non-linear covariate trends, multiple measurements at a location and clustered observations are easily handled using the geoadditive model. We propose a likelihood based estimation procedure that enables the estimation of the range (spatial decay) parameter associated with the penalized splines of the spatial component in the geoadditive model. We present how the spatial covariance structure (covariogram) can be derived from the geoadditive model. In a simulation study, we show that the underlying spatial process and prediction of the spatial map are estimated well using the proposed likelihood based estimation procedure. We present several applications of the proposed methods on real-life data examples.     

The role of the cloud optical thickness in the attenuation of the solar ultraviolet radiation reaching the ground: Implications to the human health impacts

Cloud optical depth, as it is derived from the King's method, is compared with that deduced from the simple two stream approximation for the greater Athens, Greece area. The results show that King's method overestimates the cloud optical thickness, in comparison to the two stream approximation. These estimations were also compared with satellite observations provided by the International Satellite Cloud Climatology Project. This comparison showed that there are large deviations between ground‐based and satellite observations. These deviations are probably due to the uncertainty introduced by the integration procedure of the satellite spatial analyzing resolution (distinctness). Furthermore, values of the simple scattering albedo were calculated by employing a recently proposed theoretical method and using the solar ultraviolet irradiance measurements performed at the Athens University on a routine basis. These results are of great importance for the densely populated areas like Athens, in a sense of health impacts, from enhanced incident solar ultraviolet radiation.     

Productivity alters the scale dependence of the diversity-invasibility relationship

At small scales, areas with high native diversity are often resistant to invasion, while at large scales, areas with more native species harbor more exotic species, suggesting that different processes control the relationship between native and exotic species diversity at different spatial scales. Although the small-scale negative relationship between native and exotic diversity has a satisfactory explanation, we lack a mechanistic explanation for the change in relationship to positive at large scales. We investigated the native-exotic diversity relationship at three scales (range: 1-4000 km2) in California serpentine, a system with a wide range in the productivity of sites from harsh to lush. Native and exotic diversity were positively correlated at all three scales; it is rarer to detect a positive relationship at the small scales within which interactions between individuals occur. However, although positively correlated on average, the small-scale relationship between native and exotic diversity was positive at low-productivity sites and negative at high-productivity sites. Thus, the change in the relationship between native and exotic diversity does not depend on spatial scale per se, but occurs whenever environmental conditions change to promote species coexistence rather than competitive exclusion. This occurred within a single spatial scale when the environment shifted from being locally unproductive to productive.     

On the biology of the Antarctic krillEuphausia superba

Results are described of observations on the distribution and biology of the Antarctic krillEuphausia superba Dana in the Scotia Sea and off South Georgia, conducted on board the R.V. Academic Knipovich from february 13 to April 2, 1968. Commercial concentrations of krill were observed between the South Orkneys and the South Sandwich Islands. Trial commercial fishing resulted in 136 t/10 days, with an average catch of 2 t/h and a maximum catch of 7 t/h. Catches decreased in the morning, from 4 a.m. to 12 a.m. Northwest of South Georgia concentrations of krill were also observed. Krill tend to concentrate in areas with circular water movement, but the problem of prompt location of commercial concentrations has not yet been solved. According to size composition curves, krill become mature only at 3 years of age and breed in the fourth year of their life. Only a few individuals survive to the age of 4 years.     

Assessment of the Water Quality of the River Arno in the Area of Florence, Italy

The quality of the waters collected from R. Arno was examined in the period September 1988 to December 1989. A first campaign in September/October 1988, during a period of low water, gives a general picture of pollution conditions along the river from the source to the mouth. the river appears to be heavily polluted immediately downstream of Florence and in the area of the textile industry.

In the second campaign, through the whole year 1989, particular attention has been given to the Florence area; the most significant results, compared with those from a previous investigation carried out in 1971, show only a small reduction of the pollution load, due to the shortage and inadequacy of wastewater depuration. Some considerations are reported on pollution drop with full spate.     

Beliefs about the environment: moving from the egocentric towards the ecocentric perspective

Our behaviour towards the environment depends on our beliefs about the environment. Beliefs, however, are a subject of change, particularly during important life transitions such as the transition to adolescence, because this is a period when an individual develops the ability of complex and abstract reasoning. Understanding this transition is therefore crucial for understanding and predicting the attitudes and courses of action in terms of sustainable development later in life. Due to many methodological constraints, the number of empirical studies examining these issues is very limited; the current study aimed to collect empirical data to explore the origins of our beliefs about the environment-related issues. We devised a picture association test and used it to compare children’s and adolescents’ beliefs about our environment in the context of the means of transportation. A large sample of 2264 participants aged 6–18 years took part in the study. The data supported the claim that children’s beliefs about environment share egocentric properties. The findings represent an important puzzle into the whole picture of children’s thinking and offer us great insight into the origins of beliefs about environment-related questions in adults. Educational implications are addressed.     

Dynamic preservation of the coastline in the Netherlands

In 1990, the Government and Parliament of the Netherlands decided on a new national policy for coastal defence. To ensure the enduring safety of the low-lying polders as well as the sustainable preservation of the coastal dunes, it was decided to maintain the coastline in its 1990 position. The main method for coastline preservation in the Netherlands is beach nourishment. Since 1991, approximately 7 million m³ of sand is added to the Dutch beaches annually. From an evaluation study of sand nourishment projects it is concluded that nourishment is an effective and efficient method to preserve the coastline. The evaluation study also proves that nourishment projects should be ‘tailor-made’, taking the local morphological and hydraulic conditions into account. The first results of an experimental shoreface nourishment are discussed. The choice for nourishment as the principal method to combat erosion is well in line with the intention to restore the natural dynamics of the dune-coast in the Netherlands. The key probably is a less strict policy with regard to the maintenance of the foredunes. Plans for the development of typical coastal features such as slufters^*, wash-overs, blow-outs and mobile dunes are currently under discussion. A slufter is a breakthrough in the first dune-ridge whereby the sea invades former dune slacks or beach plains situated behind the duneridge. In this way a tidal marsh is formed within the dune zone.     

Sampling animal association networks with the gambit of the group

Ecologists increasingly use network theory to examine animal association patterns. The gambit of the group (GoG) is a simple and useful assumption for accumulating the data necessary for a network analysis. The gambit of the group implies that each animal in a group is associating with every other individual in that group. Sampling is an important issue for networks in wild populations collected assuming GoG. Due to time, effort, and resource constraints and the difficulty of tracking animals, sampled data are usually a subset of the actual network. Ecologists often use association indexes to calculate the frequency of associations between individuals. These indexes are often transformed by applying a filter to produce a binary network. We explore GoG sampling using model networks. We examine assortment at the level of the group by a single dichotomous trait, along with many other network measures, to examine the effect of different sampling regimes, and choice of filter on the accuracy and precision with which measures are estimated. We find strong support for the use of weighted, rather than filtered, network measures and show that different filters have different effects depending on the nature of the sampling. We make several practical recommendations for ecologists planning GoG sampling.     

Uncertain sightings and the extinction of the Ivory-billed Woodpecker

The extinction of a species can be inferred from a record of its sightings. Existing methods for doing so assume that all sightings in the record are valid. Often, however, there are sightings of uncertain validity. To date, uncertain sightings have been treated in an ad hoc way, either excluding them from the record or including them as if they were certain. We developed a Bayesian method that formally accounts for such uncertain sightings. The method assumes that valid and invalid sightings follow independent Poisson processes and use noninformative prior distributions for the rate of valid sightings and for a measure of the quality of uncertain sightings. We applied the method to a recently published record of sightings of the Ivory-billed Woodpecker (Campephilus principalis). This record covers the period 1897-2010 and contains 39 sightings classified as certain and 29 classified as uncertain. The Bayes factor in favor of extinction was 4.03, which constitutes substantial support for extinction. The posterior distribution of the time of extinction has 3 main modes in 1944, 1952, and 1988. The method can be applied to sighting records of other purportedly extinct species.