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The composition of phytoplankton and the general distribution patterns of the major taxonomic groups are discussed for the eastern coastal waters of the USA. A species list of 609 phytoplankters is given with dominant cold- and warm-water forms noted along the coast. The ubiquitous species along the east coast were Skeletonema costatum, Thalassionema nitzschioides, and Coccolithus huxleyi.  相似文献   

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Cataloging biodiversity is critical to conservation efforts because accurate taxonomy is often a precondition for protection under laws designed for species conservation, such as the U.S. Endangered Species Act (ESA). Traditional nomenclatural codes governing the taxonomic process have recently come under scrutiny because taxon names are more closely linked to hierarchical ranks than to the taxa themselves. A new approach to naming biological groups, called phylogenetic nomenclature (PN), explicitly names taxa by defining their names in terms of ancestry and descent. PN has the potential to increase nomenclatural stability and decrease confusion induced by the rank‐based codes. But proponents of PN have struggled with whether species and infraspecific taxa should be governed by the same rules as other taxa or should have special rules. Some proponents advocate the wholesale abandonment of rank labels (including species); this could have consequences for the implementation of taxon‐based conservation legislation. I examined the principles of PN as embodied in the PhyloCode (an alternative to traditional rank‐based nomenclature that names biological groups based on the results of phylogenetic analyses and does not associate taxa with ranks) and assessed how this novel approach to naming taxa might affect the implementation of species‐based legislation by providing a case study of the ESA. The latest version of the PhyloCode relies on the traditional rank‐based codes to name species and infraspecific taxa; thus, little will change regarding the main targets of the ESA because they will retain rank labels. For this reason, and because knowledge of evolutionary relationships is of greater importance than nomenclatural procedures for initial protection of endangered taxa under the ESA, I conclude that PN under the PhyloCode will have little impact on implementation of the ESA. Impactos de la Nomenclatura Filogenética sobre la Eficiencia del Acta Estadunidense para las Especies en Peligro  相似文献   

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Studies were made of some carotenoids extracted from Axinella verrucosa (O. schmidt) (Porifera: Demospongiae), a species which occurs in the Gulf of Naples. -carotene, renieratene, isorenieratene, and an unknown isomer of renieratene have been isolated.  相似文献   

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The estimated levels of genetic variation are reported for 6 Crassostrea and 3 Saccostrea species. The estimates are based on examination of 25 to 34 genetic loci. The average heterozygosities ranged from 6 to 22% for the Crassostrea species and from 17 to 19% for the Saccostrea species. A new sibling species (S. manilai) from the Philippines has been identified by means of protein electrophoresis. The genetic similarity and distance between species has been computed for each genus. Also, a pairwise comparison of loci and a dendrogram of the phylogenetic relationship of species has been constructed from the two genera. Some of the taxonomic levels during oyster speciation have been computed from the data of the electrophoretic study of the two lineages. The possibilities of oyster superspecies (e. g. C. gigas, C. virginica and S. cucullata) are discussed based on our population genetic study.  相似文献   

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Gel filtration on highly cross-linked molecular sieves of the sperm attractants of some hydromedusae revealed that the active agents differ in their molecular weights. These differences fall roughly along taxonomic lines, at least at the order level. Anthomedusae have attractants with molecular weights greater than 5,000, while the Leptomedusae attractants have weights less than 1,000. The Limnomedusae and Trachymedusae attractants have weights above 5,000. All the attractants are heat-stable, but only those of the Leptomedusae can pass across a dialysis membrane with a molecular weight cut-off of 14,000.  相似文献   

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A technique utilizing combined fixation and gentle decalcification has been employed to study the ultrastructure of the vegetative cells of the articulated calcareous coralline algae Corallina officinalis Linnaeus and C. cuvierii Lamouroux (Rhodophyta: Cryptonemiales). The epidermal cells are distinctive, with many cell wall inggrowths which pass between the chloroplasts. It is suggested that these cells function as transfer cells. The epidermal cells contain no starch, although the chloroplasts have well developed photosynthetic lamellae. Damage to these epidermal cells leads to formation of new cells by renewed division of sub-epidermal meristematic cells. The outer cortical cells have few small vacuoles and many plastids, with an extensive photosynthetic lamellar system. Deeper into the thallus, the vacuoles increase in size and free cytoplasmic starch grains occur. The medullary cells have a very large vacuole and in older tissue often appear dead. The long genicular cells have calcareous walls at either end while the wall in the middle of these cells is non-calcareous and has an inner fibrillar layer and a thin outer cuticle. In partially decalcified material, the orientation of the CaCO3 (calcite) crystals next to the cells can clearly be seen. Immediately next to the cell the crystals are fairly small and arranged at right angles to the plasmalemma. Further away from the cell the crystal size is larger and their orientation is more random. The crystals are surrounded by organic material, and the possible rôle of this material in calcification in coralline algae is discussed.  相似文献   

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The luminescence of the solitary radiolarianThalassicolla sp. has a spectral emission maximum at 446±4 nm and the luminescence of crude homogenates can be activated by calcium ions. Electrical stimulation of single individuals frequently causes them to produce repetitive post-stimulus flashing akin to that reported in a number of other marine animals. The possible relationships between the luminescent system ofThalassicolla sp. and of certain coelenterates are discussed.  相似文献   

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This paper reviews the history and evolution of the United States National Wildlife Refuge System, perhaps the largest and oldest wildlife conservation system in the world. The refuge system is guided by the doctrine of compatibility, which permits only those uses on a refuge which are "compatible with the purposes for which the refuge was established." Memoranda and documents spanning the last 100 years were examined, and key refuge personnel interviewed, to understand the historical basis for current refuge policies. Topics of particular importance were the origins of the compatibility doctrine, the origin and meaning of the sanctuary concept, and the means by which refuges were established.
Through time, the refuge system has shifted from a policy of strict protection of wildlife to a policy of integrating public uses of refuges. The doctrine of compatibility has evolved to facilitate public use of wildlife refuges. Increasingly, the needs for recreation and resource use have interfered with the purposes far which refuges were established. A legislative solution may be needed to ensure that these areas are protected and remain viable reserves for wildlife and natural communities.
The sustained conservation of reserve areas often represents a delicate balance between political constraints and biological realities. The examination of the National Wildlife Refuge System not only has ramifications for North American conservation, but illustrates many of the problems and pitfalls facing conservation and land management worldwide.  相似文献   

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D. Liang  S. Uye 《Marine Biology》1996,127(2):219-227
Population dynamics and production of the calanoid copepodParacalanus sp. were studied from November 1986 to November 1987 in Fukuyama Harbor, a eutrophic inlet of the Inland Sea of Japan. This species was perennial, with a large abundance peak in June/July and small peaks in September/October and November/December. During a year of investigation, 15 generations Gould be detected. For each generation, the mean population egg production rate and the mean daily midstage abundance front NIII to CV were determined to obtain a survival curve from egg to CV. The mortality was extremely high during the early life stages: on average only 7.1% of the eggs produced might survive into NIII. This high mortality might be caused by predation by sympatric omnivorous copepods, in addition to sinking loss of eggs from the waten column. The biomass ofParacalanus sp. showed marked seasonal variations largely in parallel with numerical abundance. The instantaneous growth rate of each developmental stage increased exponentially with temperature up to 20 °C, above which the rate was constant. The annual integrated production rate was 734 mg C m–3 yr–1 or 5.5 g C m–2 yr–1.  相似文献   

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The frequencies of certain electrophoretic fractions of esterases, transferrins and haemoglobins in an American sample of eels (Anguilla rostrata Le Sueur) are compared to those in a sample from Iceland [A. anguilla (L.)]. A number of quantitative differences were established as well as 6 contrasts of a qualitative all-or-none type. The bearing of these differences and contrasts on theories concerning a separate or a single gene pool for Atlantic eels is discussed.  相似文献   

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Abstract:  Genetic information is becoming an influential factor in determining whether species, subspecies, and distinct population segments qualify for protection under the U.S. Endangered Species Act. Nevertheless, there are currently no standards or guidelines that define how genetic information should be used by the federal agencies that administer the act. I examined listing decisions made over a 10-year period (February 1996–February 2006) that relied on genetic information. There was wide variation in the genetic data used to inform listing decisions in terms of which genomes (mitochondrial vs. nuclear) were sampled and the number of markers (or genetic techniques) and loci evaluated. In general, whether the federal agencies identified genetic distinctions between putative taxonomic units or populations depended on the type and amount of genetic data. Studies that relied on multiple genetic markers were more likely to detect distinctions, and those organisms were more likely to receive protection than studies that relied on a single genetic marker. Although the results may, in part, reflect the corresponding availability of genetic techniques over the given time frame, the variable use of genetic information for listing decisions has the potential to misguide conservation actions. Future management policy would benefit from guidelines for the critical evaluation of genetic information to list or delist organisms under the Endangered Species Act.  相似文献   

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采用室内模拟试验研究丁虫腈在水体中的光解、水解及其在3种不同类型土壤中的降解特性。结果表明,丁虫腈在酸性和中性条件下比较稳定,不易水解,而在碱性条件下水解较快,在50℃、pH值为9.0的缓冲溶液中降解半衰期为26.7d。通过对水解产物的鉴定,推断丁虫腈的水解机理为碱催化水解。在[光]照度为2500lx、紫外强度为25I.LW·cm-2的人工光源氙灯条件下,丁虫腈的降解半衰期为1.5h,主要降解产物为氟虫腈。丁虫腈在太湖水稻土、江西红壤和陕西潮土中培养180d后均未发生明显降解,表明该农药在土壤中较难降解。  相似文献   

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The law governing large carnivores in the western U.S. and western Canada abounds in jurisdictional complexity. In the U.S., different federal and state laws govern large carnivore conservation efforts; species listed under the Endangered Species Act are generally protected, whereas those subject to state regulation can be hunted, trapped, or otherwise taken. Neither federal nor state environmental or land management laws specifically protect large carnivores, though these laws can be used to protect habitat. A similar situation prevails in Canada. Canadian federal law does not address large carnivore conservation, although the national parks provide some secure habitat. Provincial laws vary widely; none of these laws specifically protect large carnivores, but some provisions can be invoked to protect habitat. Although the two nations have not entered any bilateral treaties to protect large carnivores, several species receive limited protection under multilateral treaty obligations. Despite these jurisdictional complexities, the existing legal framework can be built upon to promote large carnivore conservation efforts, primarily through a legally protected reserve system. Whether the political will exists to utilize fully the available legal authorities remains to be seen.  相似文献   

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Spatial pattern in the distribution of the macrobenthos was studied from series of van Veen grab samples taken in a systematic pattern in Lochs Etive and Creran, W. Scotland. Each series was collected in a circular pattern at 7 stations. Plots of the variances of the numerical occurrences of the species in the samples against their means revealed greater deviation from the random expectation in the case of the 2 muddy sand stations than for the soft-mud stations, with only 1 exception. Two tests of goodness-of-fit to the Poisson distribution were also applied. The degree of concordance between the 3 measures of non-randomness applied was measured. The best correlation was found between values of the ratio of variance: mean and the test statistic D of the Kolmogorov-Smirnov goodness-of-fit test. It was not possible to discuss the biological basis for the pattern measured, except for a few species shown to be markedly aggregated. No clear trend emerged from attempts to detect differences in pattern with various ecological groupings of the macrobenthos. However, from the use of the test values as sample statistics illustrative of overall community pattern, it was possible to conclude that the fauna of the shallow, usually current-swept areas of muddy sand in the sea-lochs investigated was more aggregated than that on the, usually deeper, soft-mud sediments in quieter water.  相似文献   

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