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1.
Several works on public perception of bathing area quality state that litter is one of the top concerns of users. Litter was also considered the top concern of bathing users regarding Bathing Area (BA) quality in S?o Miguel (Azores). This fact highly justifies the need to evaluate BA in this perspective. During 2009 summer 11 bathing areas, covering all the proposed BA typologies in S?o Miguel Island, were assessed and rated according to litter. The methodology was based on the EA/Protocol (Environmental Agency (UK)/National Aquatic Litter Group 2000). BA were graded from A to D (very good, good, fair and poor) on several litter categories: sewage related debris, gross litter, general litter, harmful litter, accumulations, oil or similar and faeces. Transects were sampled at 7 (o??clock) p.m. on sunny Sundays to achieve extreme situations. From the bathing areas assessed 4 were rated B (Good) and 7 rated C (Fair). During the same period the users perception regarding litter was assessed. Data obtained was related to bathing areas Scenic Evaluation Index (D) value, establishing a 5-class evaluation system. Some interactions between these factors (litter, BA typologies, public perception and scenic value) were analyzed and discussed. Scenic value doesn??t seem to affect users behavior regarding litter, however seems to affect the perception of users. Some of the bathing areas typologies seem to be more affected by litter, especially Urban and Semi-urban sandy beaches. BA cleaning processes and the relation of users with the area are the main reasons to this fact.  相似文献   

2.
Are elected politicians primarily motivated by holding office, thus choosing environmental policies accordingly? Or are they motivated by the chance to implement their preferred environmental policies? Do governors have character, in the sense that they promise and implement environmental policies consistent with their own preferences? To answer these questions, we study the differences in environmental spending across both re-electable and lame duck governors from the two main political parties. In our empirical analysis, we make use of parametric and non-parametric regression-discontinuity approaches. While re-electable governors do not set significantly different policies, lame duck governors do. We argue that in the area of environmental policy governors appear to be primarily office motivated and lack character.  相似文献   

3.
Accelerated sea level rise (slr) is expected to transform vulnerable Atlantic coastal habitats in the United States during this century. Low-elevation sandy beaches, important nesting habitat for the continued recovery of the federally threatened piping plover (Charadrius melodus) in Rhode Island, are especially vulnerable. These beaches, under a mix of private and public ownership, exist in a heterogeneous landscape of dunes, rocky headlands, salt ponds, and heavily developed areas. Understanding the extent to which piping plover nesting beaches can retreat landward under projected slr is important for prioritizing future conservation actions across multiple jurisdictions. This research examines habitat change in response to slr (0.5, 1.0, and 1.5 m) under stationary and migration beach responses and whether development blocks habitat migration for five productive piping plover nesting beaches. We found that under the stationary habitat model, all beaches lose area under all slr scenarios. For the habitat migration model, future habitat availability differs by beach depending on elevation, landward topography, and presence of development. However, across the majority of beach area, piping plover habitat will be able to migrate landward if unconstrained by future development. A coalition of public and private stakeholders already supports management efforts to help ensure plover population recovery in the area. With emerging habitat change prediction tools, these stakeholders and other partners can engage in innovative, local-level planning needed to protect wildlife habitat and commercial, residential, and infrastructure assets from sea level rise.  相似文献   

4.
Encroachment of tall grasses and shrubs in coastal dunes has resulted in loss of vegetation heterogeneity. This is expected to have negative effects on animal diversity. To counteract encroachment and develop structural heterogeneity grazing is a widely used management practice. Here, we aim to functionally interpret changes in vegetation composition and configuration following grazing management on habitat suitability for sand lizards. Aerial photographs taken over a period of 16 years were used to quantify changes in vegetation composition. A GIS-based method was developed to calculate habitat suitability for sand lizards in a spatially explicit manner, encompassing differences in vegetation structure and patch size. From 1987 to 2003 dune vegetation shifted from small patches of moss and sand to larger patches covered by shrubs and grasses. Grazing management did not have any significant effect on the overall level of heterogeneity, measured as habitat suitability for sand lizards. However, on a more local scale highly suitable patches in 1987 were deteriorating whereas unsuitable patches became more suitable in 2003. This inversion results from a broad shift with shrubs being a limiting habitat element in 1987 to sandy patches being the limiting element in 2003. Future changes are believed to negatively impact sand lizards. The habitat suitability model has proven to be a useful tool to functionally interpret changes in coastal dune vegetation heterogeneity from an animal’s perspective. Further research should aim to include multiple species operating on different scale levels to fully capture the natural landscape dynamics.  相似文献   

5.
While our understanding of the early oceanic developmental stage of sea turtles has improved markedly over recent decades, the spatial context for this life history stage remains unknown for Indian Ocean loggerhead turtle populations. To address this gap in our knowledge, 18 juvenile loggerheads were satellite tracked from Reunion Island (21.2°S, 55.3°E) between 2007 and 2011. Nine turtles swam north toward Oman (20.5°N, 58.8°E), where one of the world’s largest rookeries of loggerheads is located. Three individuals traveled south toward South Africa and Madagascar, countries that also host loggerhead nesting grounds. Fourteen of the transmitters relayed diving profiles. A dichotomy between diurnal and nocturnal diving behavior was observed with a larger number of shorter dives occurring during the day. Diving behavior also differed according to movement behavior as individuals spent more time in subsurface waters (between 10 and 20 m) during transit phases. The study provides an understanding of the oceanic movement behavior of juvenile loggerheads in the Indian Ocean that suggests the existence of an atypical trans-equatorial developmental cycle for the species at the ocean basin scale in the Indian Ocean. These results address a significant gap in the understanding of loggerhead oceanic movements and may help with the conservation of the species.  相似文献   

6.
The Hammam Lif shoreline, which is part of the Gulf of Tunis (North-East of Tunisia), suffered from a dramatic erosion event during a storm in 1981. Therefore, eight successive and detached breakwaters were built to protect it. The effect of these protection works on the evolution of this coastline is assessed using aerial photographs geo-referenced by digital photogrammetric methods. Results show that a general accretion has developed behind the detached breakwaters, with the formation of seven tombolos and one salient. The response of the coastline depends on the characteristics of the protective works (length, distance to coast, and spacing). Detached breakwaters which are short, far from the coastline and distant from each other, give rise to very small tombolos or salients. On the other hand, longer breakwaters which are near the coastline and closely spaced, give rise to more developed tombolos, showing that these structures are the most efficient.  相似文献   

7.
We used both field and flight cage observations to investigate the echolocation and foraging behavior of the seldom studied, small, aerial insectivorous bat Myotis nigricans (Vespertilionidae) in Panama. In contrast to its temperate congeners, M. nigricans foraged extensively in open space and showed an echolocation behavior well adapted to this foraging habitat. It broadcast narrowband echolocation signals of 7 ms duration that enhance the chance of prey detection in open space. Because of rhythmical alternations of signal amplitude from signal to signal in our sound recordings of search signals in open space, we conclude that the bats scanned their environment with head movements, thereby enlarging their search volume. In edge-and-gap situations, and in the flight cage, M. nigricans introduced an initial broadband component to its search calls. In the field and in the flight cage, M. nigricans hawked for prey in aerial catches; gleaning was never observed. M. nigricans demonstrates call structures, such as narrow bandwidth and rather long signals adapted to foraging predominantly in open space. Moreover, call structure is highly plastic, allowing M. nigricans to forage in edge-and-gap situations also. These adaptations in call structure and plasticity have evolved convergently at least twice within the genus Myotis. Finally, M. nigricans echolocation and foraging behavior parallels that of the small, aerial, insectivorous pipistrelle bats (Vespertilionidae), which are not closely related to M. nigricans but forage in similar habitats.  相似文献   

8.
Large (to >1 m), diurnally active tiger snakes (Notechis scutatus) are abundant on Carnac Island, near the coast of Western Australia. Our behavioural and mark-recapture studies provide the first ecological data on this population, and reveal a surprising phenomenon. Many adult tiger snakes have had their eyes destroyed, apparently during nest defence, by silver gulls (Larus novaehollandiae). This loss of vision did not reduce the snakes' body condition (mass relative to length), or their rates of growth or survival (measured over a 12-month period). Blind male snakes trail-followed females, and mated successfully. Thus, destruction of a major sensory modality had no detectable effect on these predators. This result is strongly counter-intuitive, but mirrors an earlier report of congenital blindness (without ill-effects) in American viperid snakes. Similarities between the two systems (island populations, highly venomous snakes, reliance on sessile prey) clarify the circumstances under which the loss of vision does not reduce an organism's viability. These natural experiments support Gans' hypothesis of “momentarily excessive construction” in that the snakes possess a complex organ system that they do not actually require for successful feeding, survival or reproduction. Received: 30 November 1998 / Received in revised form: 24 April 1999 / Accepted: 9 May 1999  相似文献   

9.
Phascolosoma perlucens is one of the most common intertidal sipunculan species and has been considered a circumtropical cosmopolitan taxon due to the presence of a long-lived larva. To verify whether P. perlucens is a true cosmopolitan species or a complex of cryptic forms, we examined the population structure and demographics of 56 putative P. perlucens individuals from 13 localities throughout the tropics. Analysis of two mitochondrial markers, cytochrome c oxidase subunit I and 16S rRNA, suggests high levels of genetic differentiation between distantly located populations of P. perlucens. At least four different lineages identified morphologically as P. perlucens were distinguished. These lineages are likewise supported by phylogenetic analysis of the two mitochondrial markers and by the haplotype network analysis. Our results suggest that P. perlucens is a case of overconservative taxonomy, rejecting the alleged cosmopolitanism of P. perlucens. However, cryptic speciation also exists in some areas, including a possible case of geminate species across the Isthmus of Panama.  相似文献   

10.
Arctic cod (Boreogadus saida) is a schooling fish providing a critical link between lower and upper trophic levels in the Arctic. This study examined foraging of Arctic cod collected from Allen Bay, Cornwallis Island, Canada (~75 N 95 W), during summer 2010 using temporal indicators of diet including stomach content, and carbon (δ13C) and nitrogen (δ15N) stable isotopes of liver and muscle. Foraging at the time of capture reflected sympagic and epi-benthic habitats indicated by the prevalence of cyclopoid and harpacticoid copepods in stomachs, whereas stable isotope data, which provide an estimate of feeding over a longer period, indicated pelagic prey as important. Prey selection of juveniles differed from adults based on stable isotopes, while large adults showed the most separation based on stomach contents, suggesting size-related diet shifts. Compared to studies near Resolute in the 1970s, 1980s, and 1990s, growth and pre-spawning gonadal conditions of Arctic cod have not changed.  相似文献   

11.
Gametogenesis, spawning behavior, and early development have been described in the methane-seep polychaete Hesiocaecamethanicola Desbruyères and Toulmond, 1998, the first documentation of the reproductive biology of any cold-seep polychaete species. The worms were collected at the Green Canyon site in the Gulf of Mexico (27°44.77N; 91°13.33W) in August 1997. The gonads are situated in the neuropodia in association with an intraepithelial capillary system. Oogenesis is intraovarian, with oocytes remaining in the ovary until late vitellogenesis when they are released into the coelom for final growth and differentiation. Vitellogenesis involves both autosynthetic and heterosynthetic processes and, along with ovarian structure, suggests a relatively slow process of egg formation. Sperm differentiation is intertesticular until early spermiogenesis, when spermatid tetrads complete development in the coelom. The mature spermatozoon is an ect-aquasperm consisting of a tapering, digitate acrosome, a spherical nucleus, a midpiece containing from six to eight mitochondria and glycogen stores, and two centrioles associated with the flagellum. Both sexes undergo broadcast spawning, but the males spawn exclusively through the anus, a behavior previously unknown in polychaetes. Artificial fertilization resulted in spiral cleavage and development to the trochophore stage. Oocyte size-frequency analysis of adult females indicates a wide range of oocyte sizes and vitellogenic stages, suggesting that asynchronous gametogenesis occurs. Received: 13 July 2000 / Accepted: 29 November 2000  相似文献   

12.
The seasonal variations of Chlorophyll-a was examined in relation to phytoplankton density and physico-chemical factors in Demird?ven Dam Reservoir during 2000-2001. Chlorophyll-a concentrations ranged from 0.62 to 7.19 mg/m3 and from 0.67 to 8.88 mg/m3 in 2000 and 2001, respectively. Maximum Chlorophyll-a concentrations were found near the metalimnion and decreased with depth. Chlorophyll-a concentrations showed positive correlation to phytoplankton density, water temperature and nutrient concentrations, and negative correlations to Secchi depth. Demird?ven Dam Reservoir can be classified as a mesotrophic reservoir according to Chlorophyll-a concentrations.  相似文献   

13.
Deep black clayey sediments of the Dead Sea, previously covered with water at times of higher sea level, are being mined for therapeutic purposes and for the preparation of cosmetic products under the name Black Mud. It was claimed that the beneficial properties are due to the presence of bitumen (asphalt) as attested by the colour. Less commonly, the curative properties have been ascribed to humic acids or to organic matter derived from algae in the lake. Asphalt from the Dead Sea has been of major economic importance to the region and was used as a medication for 2000 years until the mid-20th century. Geochemical analysis of the Black Mud showed that it contains relatively little organic matter (ca. 0.6–0.8% organic carbon) and that the organic matter is mostly derived from the land masses surrounding the lake. Asphalt was totally absent and the concentration of humic acids very low. The black colour of the mud is rather due to the poorly crystallised iron sulphides. Based on this, the therapeutic properties of the mud are ascribed to its content of reduced sulphur species, its physical and chemical properties and possibly its brine content, but not to the presence of organic matter.  相似文献   

14.
Pre-spawning reproductive biology and population structure of the sea cucumber Isostichopus fuscus were analysed at the Caamaño Island, Galápagos Islands, Ecuador on a monthly basis between January 1995 and June 1996. An average of 25 individuals of all sizes were collected each month. Using microscopic characteristics of the gonads three gonadal stages were described: (1) immature; (2) mature, and (3) spent. Mature individuals showed statistically different morphometric characteristics. I. fuscus was continuously sexually mature throughout the year independent of changes in sea water temperature. Mean oocyte diameter indicated planktotrophic larval development. Mean fecundity for this species was 567,884 (±95,528 SE) eggs per gonad. Size at first maturity was between 161.0 and 170.9 g drained weight and the smallest individual found with mature gonads had a drained weight between 121.0 and 130.9 g. The population sampled ranged between 13 and 31 cm (81.0–400.0 g) with less than 10% of the population of individuals ≥25 cm (≥300.0 g). No juveniles were recorded.  相似文献   

15.
16.
Though it is known that flower scent not only attracts pollinators but also herbivores, little is known about the importance of flower scent on the distribution of leaf herbivores among individuals within a plant species. In this study we determined the distribution of galls induced by the sawfly Pontania proxima (Serville 1823) (Hymenoptera, Tenthredinidae, Nematinae) on flowering and non-flowering representatives of several clones belonging to Salix fragilis and S. × rubens (Salicaceae). Further, amounts and composition of scent of flowering and non-flowering twigs were compared (dynamic headspace-gas chromatography–mass spectrometry, DHS-GC–MS), and a scent sample collected from flowering twigs of S. fragilis was tested by coupled gas chromatography and electroantennographic detection (GC-EAD) on the antennae of P. proxima females. The results show that the presence of flower catkins on plants led to a higher degree of allocation with galls, but the number of galls differed not between flowering and non-flowering plants. The DHS-GC–MS analyses revealed that the total amount of flower scent emitted per flowering twig is about 90 times higher than the scent emitted by a non-flowering twig. Further, several compounds were emitted only by flowering but not by non-flowering twigs. In the GC-EAD analyses, antennae consistently responded not only to green leaf volatiles, but also to compounds emitted only by the flowers (e.g. 1,4-dimethoxybenzene). These flower scent compounds are suggested to affect the host plant choice by attracting more sawflies from the distance to flowering plants compared to non-flowering plants. The EAD-active compounds emitted from vegetative plant parts are assumed to act as long-distance signals especially when flowers are absent on host plants, e.g. during the oviposition period of the second generation of P. proxima.  相似文献   

17.
Phylogeographic patterns among coastal fishes are expected to be influenced by distinct ecological, biological and life history traits, along with historical events and oceanography (past and present). This study focuses on the broad range phylogeography of the Montagu’s blenny Coryphoblennius galerita, a species with well-known ecological features, strictly tied to rocky environments and with limited dispersal capability. Eleven locations from the western Mediterranean to the Bay of Biscay (including the Macaronesian archipelagos) were sampled. Mitochondrial DNA control region (CR) and the first intron of the S7 ribosomal protein gene were used to address the population structure, the signatures of expansion/contraction events retained in the genealogies and potential glacial refugia. The genetic diversity of the Montagu’s blenny was high throughout the sampled area, reaching maximum values in the Mediterranean and western Iberian Peninsula. The results confirmed a marked structure of C. galerita along the sampled area, with a major separation found between the Mediterranean and the Atlantic populations, and suggesting also a separation between the Azores and the remaining Atlantic locations. This study revealed complex and deep genealogies for this species, with Montagu’s blenny populations presenting signatures of events clearly older than the Last Glacial Maximum, with lineages coalescing in early Pleistocene and Pliocene. Three potential glacial refugia where this species might have survived Pleistocene glaciations and from where the recolonization process might have taken place are suggested: South of Iberian Peninsula/North Africa, Mediterranean and Azores.  相似文献   

18.
To estimate species turnover rates on scales of several tens of km in deep-sea benthic animals, we analyzed spatial and inter-annual changes in species diversity and composition of cerviniids, a typical group of deep-sea harpacticoids, at stations in and around Sagami Bay, central Japan. Associations with environmental factors were also investigated. Generally, bathymetrical patterns in diversity of benthos are unimodal and peak at depths of 2,000–3,000 m. In Sagami Bay, cerviniid diversity did not follow this trend; both species richness and evenness were negatively correlated with water depth. Multivariate analyses [detrended correspondence analysis (DCA) and non-metric multi-dimensional scaling] suggested that temporal changes in species composition of cerviniids are smaller than spatial changes that occur on horizontal scales of several tens of km. Community structure does not change completely on these scales in the bathyal zone around Sagami Bay. DCA also showed that bathymetrical changes in species composition can be regulated by certain factors associated with water depth.  相似文献   

19.
Established research in first world urban environments has shown street sediments to be effective sinks for heavy metals and emphasises the health risks to children by its inhalation or ingestion. In third world countries with fewer pollution controls, contamination may be augmented by additional pollutants such as sewage discharge into urban streets and/or periodic inundation with sewage-laden run-off. This pollutant not only contains heavy metals and organic matter, but calcium oxalates that may derive directly from the sewage itself. To study this premise street sediments were collected from sites of varying industrialisation and sewage contamination within the city of Niteroi, Brazil. Calcium oxalate dihydrate (weddellite) was identified by X-ray diffraction, fourier transform infra red and scanning electron microscopy techniques and oxalate concentrations in <63m and colloidal (clay and organic matter) fractions, were determined by ion chromatography. Oxalate in colloidal fractions averaged 43601mgkg–1 in sewage contaminated industrialised urban zones, 4519mgkg–1 in suburban areas and 17477mgkg–1 in suburbs with favelas (shantytowns-of Niterói). Oxalate concentrations coincide with high levels of metal ions (Fe, Mn, Zn, Pb, Ni, Cr) that stabilise calcium oxalate dihydrate and prevent its dehydration to the monohydrate (whewellite). Lower levels of oxalate were found in lichen-covered roof sediment, plaster and mortar samples. Oxalate concentration coincides with sewage contamination and street sediments appear to act as a sink for calcium oxalate dihydrate derived from sewage. Previous studies have shown that low levels of exposure can damage kidneys and the nervous system, while prolonged exposure can cause severe corneal, retinal and skin damage, cyanosis and possibly gangrene. Contact with blood serum may result in hypocalcemia, muscular stimulation, convulsions and finally collapse. The conditions described are common throughout urban areas of the developing world and may suggest a particular environmental hazard in these regions.  相似文献   

20.
SUMMARY

Numbers of sika deer (Ceruus nippon), resident in the Dilijan Reserve in 1969 (52 animals), 1970 (50), 1972 (1), and 1976 (28) dramatically increased in number until 1981, when the population reached a ceiling, being the number which can subsist in the area—300 individuals (density—11–12.5 deer per 1000 ha). Thus, Dilijan Reserve's C. nippon population develops in a way which resembles an S-like log curve equation.

Actually, Dilijan Reserve no longer has the status of a protected area—nowadays lumbering activities predominate and, inevitably, the unique broadleaf deciduous forest ecosystem will run down to extinction. Such economically valuable species as oak, beech, and sika deer are likely to be the first victims of this large-scale devastation.

The present article does not reject exploitation of any resource (including sika deer), if necessary. The key question is: how C. nippon can be sustainably utilized, so that the number of culled animals is replenished within the same year and and so that eventually the population size will remain constant?  相似文献   

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