At the beginning of their offshore migration, hatchling sea turtles orient directly into oceanic waves as they swim away
from land. Recent experiments have demonstrated that hatchlings swimming underwater can determine the propagation direction
of waves by monitoring the circular movements they experience as waves pass above. During July and August 1993, we studied
how loggerhead sea turtle hatchlings (Caretta caretta L.) from the east coast of Florida, USA, responded to a range of wave parameters. We constructed a wave simulator to reproduce
in air the circular movements that normally occur beneath small ocean waves. Hatchlings suspended in air and subjected to
these orbital movements attempted to orient into simulated waves when periods and amplitudes were similar to those found near
the Florida coast. Orbital movements with longer periods (greater than 10 s), however, failed to elicit responses. The results
demonstrate that hatchling loggerheads can distinguish between waves with different periods and amplitudes, and that Florida
hatchlings respond most strongly to orbital movements closely resembling those of waves that occur near their natal beach.
Received: 28 May 1996 / Accepted: 17 September 1996 相似文献
Objective: Increased numbers of people riding pedal cycles have led to a greater focus on pedal cycle safety. The aim of this article is to explore factors that are associated with fatal and a small number of serious-injury pedal cyclist crashes involving trucks that occurred in London between 2007 and 2011.
Methods: Data were collected from police collision files for 53 crashes, 27 of which involved a truck (≥3.5 tonnes) and a pedal cycle. A systematic case review approach was used to identify the infrastructure, vehicle road user, and management factors that contributed to these crashes and injuries and how these factors interacted.
Results: Trucks turning left conflicting with pedal cyclists traveling straight ahead was a common crash scenario. Key contributory factors identified included the pedal cyclists not being visible to the truck drivers, road narrowing, and inappropriate positioning of pedal cyclists.
Conclusions: Crashes involving trucks and pedal cyclists are complex events that are caused by multiple interacting factors; therefore, multiple measures are required to prevent them from occurring. 相似文献
Since their official eradication from the US in 1943, the cattle-tick species Boophilus microplus and Boophilus annulatus, vectors of bovine babesiosis, frequently have penetrated a quarantine zone established along the Texas–Mexico border designed to exclude them. Inspection and quarantine procedures have eradicated reinfestations successfully within the US, but increasing acaricide resistance in Mexican B. microplus populations poses a threat to future eradication efforts. Better understanding of interrelationships among Boophilus populations, their hosts, and vegetation communities in south Texas could improve prediction of the behavior of reintroduced Boophilus populations and increase management options. To this end, we constructed a simulation model to evaluate how microclimate, habitat (i.e. vegetation) heterogeneity, and within-pasture cattle movement may influence dynamics of Boophilus ticks in south Texas. Unlike previous Boophilus tick models, this model simulates dynamics at an hourly time-step, calculates all off-host dynamics as functions of temperature and relative humidity, and runs with ground-level microclimate data collected bi-hourly in three different habitat types. Sensitivity analysis of the model showed that temperatures and relative humidities created by habitat type, as well as engorged female mass, influenced tick population dynamics most strongly. Host habitat selection, initial number of larvae per cow, and the number of cells into which the simulated pasture was divided also had a strong influence. Population dynamics appeared moderately sensitive to the proportion of Bos indicus in cattle genotypes and the larval attachment rate, while appearing relatively insensitive to factors such as mortality rate of engorged females. When used to simulate laboratory experiments from the literature, the model predicted most observed life-history characteristics fairly well; however, it tended to underestimate oviposition duration, incubation duration, and egg mortality and overestimate larval longevity, especially at low temperatures and high humidities. Use of the model to predict Boophilus population dynamics in hypothetical south Texas pastures showed that it reasonably generated qualitative patterns of stage-wise abundances but tended to overestimate on-host tick burdens. Collection and incorporation of data that appear not to exist for Boophilus ticks, such as larval lipid content and lipid-use rates, may improve model accuracy. Though this model needs refinements such as a smaller spatial resolution, it provides insight into responses of B. microplus or B. annulatus populations to specific weather patterns, habitat heterogeneity, and host movement. 相似文献
Sixteen species of native detector plants for ambient ozone have been identified for use in Central and Eastern Europe. They include the forbs Alchemilla sp., Astrantia major, Centuarea nigra, Centauria scabiosa, Impatiens parviflora, Lapsana communis, Rumex acetosa and Senecio subalpinus; the shrubs Corylus avellana, Cornus sanguinea and Sambucus racemosa; the trees Alnus incana, Pinus cembra and Sorbus aucuparia; and the vines Humulus lupulus and Parthenocissus quinquefolia. Sensitivity to ozone and symptoms have been verified under controlled exposure conditions. Under these conditions, symptom incidence, intensity and appearance often changed with time after removal from exposure chambers. Ozone sensitivity for four species: Astrantia major, Centuarea nigra, C. scabiosa and Humulus lupulus are reported here for the first time. The other 12 species have also been confirmed by others in Western Europe. It is recommended that these detector bioindicator species be used in conjunction with ozone monitors and passive samplers so that injury symptoms incidence can be used to give biological significance to monitored ambient ozone data. 相似文献
Calculating the risks and benefits of agricultural pesticides determines whether a pesticide will be registered for use on commodities. Historically, the US Environmental Protection Agency (EPA) has used very conservative estimates of health risks, particularly in the absence of data regarding actual use patterns of the pesticide and actual pesticide residue at the point of food purchase. However, when grower groups and manufacturers were faced with the problem of losing the ethylene bisdithiocarbamate (EBDC) fungicides, they approached EPA offering to provide hard data in place of estimates. Plant pathologists familiar with apple agroecosystems pointed out that different fungicides have highly specific uses in integrated pest management (IPM) programs, and that banning EBDC use on apples would probably raise total pesticide use in apples by compromising the pesticide reductions obtained under existing IPM programs. In addition, an early study showed that use-patterns could significantly reduce the amount of EBDC residue on apples. This approach led to a more realistic appraisal of both risks and benefits of the fungicides, lowering risks and raising benefits. The process ended with a registration prescribing use-patterns which result in minimal residue at harvest, thus providing valuable tools for use in IPM programs. 相似文献
Estuarine areas represent complex and highly changing environments at the interface between freshwater and marine aquatic ecosystems. Therefore, the aquatic organisms living in estuaries have to face highly variable environmental conditions. The aim of this work was to study the influence of environmental changes from either natural or anthropogenic origins on the physiological responses of Mytilus edulis. Mussels were collected in the Vilaine estuary during early summer because this season represents a critical period of active reproduction in mussels and of increased anthropogenic inputs from agricultural and boating activities into the estuary. The physiological status of the mussel M. edulis was evaluated through measurements of a suite of biomarkers related to: oxidative stress (catalase, malondialdehyde), detoxication (benzopyrene hydroxylase, carboxylesterase), neurotoxicity (acetylcholinesterase), reproductive cycle (vitelline, condition index, maturation stages), immunotoxicity (hemocyte concentration, granulocyte percentage, phagocytosis, reactive oxygen species production, oxidative burst), and general physiological stress (lysosomal stability). A selection of relevant organic contaminant (pesticides, (polycyclic aromatic hydrocarbons, polychlorobiphenyls) was measured as well as environmental parameters (water temperature, salinity, total suspended solids, turbidity, chlorophyll a, pheopigments) and mussel phycotoxin contamination. Two locations differently exposed to the plume of the Vilaine River were compared. Both temporal and inter-site variations of these biomarkers were studied. Our results show that reproduction cycle and environmental parameters such as temperature, organic ontaminants, and algal blooms could strongly influence the biomarker responses. These observations highlight the necessity to conduct integrated environmental approaches in order to better understand the causes of biomarker variations. 相似文献
Dendrochronological and oxygen–carbon isotopic analysis was conducted on tree rings collected at two different elevations from three different regions in western Anatolia, Turkey. Tree rings were sampled from Anatolian black pines (Pinus nigra Arn. subsp. pallasiana (Lamb.) Holmboe) of at least 200?years old through an N–S transect covering Bolu-Mengen (north), Kütahya–Simav, and Antalya–Alanya (south) forests. Cellulose was extracted from 5-year blocks of tree rings from lower to upper altitudes in each region. Dendrochronological site chronologies were built for each of the 6 sites, and response to climate was evaluated. The long-term δ13C chronologies comprising the period 1800–2008 strongly decline by an average of 2.5‰ from the mid-twentieth century, which corresponds with the commencement of industrialization in Turkey. Oxygen isotope (δ18O) time series show dominantly low undulations, although some high-frequency variations of up to 6‰ are also observed. As a result of latitude and continent effects, oxygen isotope values of tree rings show an average of 3‰ increase from south (Antalya) to the north (Bolu). Correlations between carbon isotope ratios yield high positive values indicating that industrial pollution exerts a major control on the δ13C systematics of the studied trees. Corrected δ13C ratios are mostly represented by strong positive responses to variations in temperature and precipitation, whereas δ18O and summer temperature/precipitation are negatively correlated. Tree-ring widths and δ18O display similar responses to the temperature and sensitivity to the climatic impact of historic volcanic eruptions, and changes in the solar irradiance record are also detected in other high-resolution paleoclimate archives for the region. 相似文献
The advent of stringent regulation of the storage of liquids in underground containers presents a new dimension to an operating practice long taken for granted. Previously, tanks went underground to provide a safe and convenient method for handling.liquids. Unfortunately, the environmental impact of leakage from those containers was not anticipated, nor were tank designs properly configured to minimize the threat. As local officials became alert to the potential for damage, public pressure forced tank owners to rethink this casual practice. Manufacturers and suppliers of tanks and associated hardware have moved rapidly to the new state of the art called for to meet the new standards for storage techniques, and to provide effective leak prevention and detection. This paper presents a chronology of the progress made to date in storage equipment and operating practices to provide the environmental protection demanded of underground tank owners and operators. Tank design, secondary containment, monitoring, spill and overfill protection, tank testing methods, and installation and closure procedures—as related to leak prevention—are presented 相似文献
Ecological indicators can facilitate an adaptive management approach, but only if acceptable levels for those indicators have
been defined so that the data collected can be interpreted. Because acceptable levels are an expression of the desired state
of the ecosystem, the process of establishing acceptable levels should incorporate not just ecological understanding but also
societal values. The goal of this research was to explore an approach for defining acceptable levels of ecological indicators
that explicitly considers social perspectives and values. We used a set of eight indicators that were related to issues of
concern in the Lake Champlain Basin. Our approach was based on normative theory. Using a stakeholder survey, we measured respondent
normative evaluations of varying levels of our indicators. Aggregated social norm curves were used to determine the level
at which indicator values shifted from acceptable to unacceptable conditions. For seven of the eight indicators, clear preferences
were interpretable from these norm curves. For example, closures of public beaches because of bacterial contamination and
days of intense algae bloom went from acceptable to unacceptable at 7–10 days in a summer season. Survey respondents also
indicated that the number of fish caught from Lake Champlain that could be safely consumed each month was unacceptably low
and the number of streams draining into the lake that were impaired by storm water was unacceptably high. If indicators that
translate ecological conditions into social consequences are carefully selected, we believe the normative approach has considerable
merit for defining acceptable levels of valued ecological system components. 相似文献