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971.
Shankar Aswani Patrick Christie Nyawira A. MuthigaRobin Mahon Jurgenne H. PrimaveraLori A. Cramer Edward B. BarbierElise F. Granek Chris J. KennedyEric Wolanski Sally Hacker 《Marine Policy》2012,36(1):1-10
This paper discusses some of the challenges and opportunities that can arise when implementing ecosystem-based management (EBM) in tropical nations. EBM creates a new series of challenges, problems, and opportunities that must be considered in light of existing governance and management frameworks in a local context. The paper presents five case studies from different parts of the tropical world, including Oceania, insular and continental Southeast Asia, East Africa, and the Caribbean, which illustrate that the implementation of EBM in watershed and marine ecosystems offers a new series of challenges and opportunities for its inclusion with existing forms of environmental governance and management. The paper suggests that EBM is best thought of as an expansion of customary management (CM) and integrated coastal management (ICM), rather than a paradigm shift, and that it has certain benefits that are worth integrating into existing systems when possible. The paper concludes that the cultural and institutional context of CM as well as the experience, technical skills, and legal basis that serve ICM programs are logical platforms from which to build EBM programs. Some guidelines for creating hybrid management regimes are suggested. In sum, declining marine species and ecosystems require urgent action, necessitating utilization of existing paradigms such as ICM and CM as a foundation for building EBM. 相似文献
972.
Twenty-nine benthic invertebrate species were registered for the Gudauta Bank in the depth range of 8–32 m in 1990. The shallow-water
biocenose was defined for the depths of less than 10 m, the biocenoses of Anadara inaequivalvis and A. inaequivalvis-Upogebia pusilla occupied the depths of 10–30 m; and the biocenosis of Pitar rudis was found for the depths of more than 30 m. The highest biodiversity and abundance of benthos was registered for the Anadara biocenoses, while the lowest, for the shallow-water ones. It was found that significant changes in the benthic communities
took place in the forty years after the predator gastropod Rapana venosa was introduced into the Black Sea. The oysters became extinct on Gudauta Bank, and the species composition of the benthic
community has been significantly depleted. Alien species of Anadara and Rapana became the most abundant by biomass, comprising more than 80% of the total biomass of the benthos. The population density
of Rapana constituted 12 ind./m2 and was the highest ever registered for the studied areas of the Black Sea. Insufficient nutrition preconditioned the small
size of the mollusks. 相似文献
973.
974.
S. P. Zakharkov V. B. Lobanov T. N. Gordeichuk T. V. Morozova E. A. Shtraikhert 《Oceanology》2012,52(3):354-363
To evaluate the structure and photosynthetic activity of the phytoplankton of the northwestern part of the Sea of Japan, the
results of the surveys conducted from February 26 to March 9, 2003, during the 30th cruise of the R/V Akademik Lavrentyev were used. The species composition was considered taking into account the influences of the hydrological conditions. In particular,
the studied water area was divided into four zones with various sizes of the mixed layer depth (MLD). An inverse relationship
between the MLD and the content of chlorophyll a (Chl a) in various zones was established. The diatom algae were the basic dominants of the composite structure of the phytoplankton
everywhere. It is revealed that, at a MLD increase, smaller forms of microalgae receive development. The intrapopulation relations
are caused by the adaptation of various species of phytoplankton to the influence of external factors, among which the size
of MLD is fundamental. 相似文献
975.
Variability in water temperature, salinity and density was investigated based on field measurements near Anzali Port, in the
Southern Caspian Sea in 2008. Seasonal changes of seawater properties were mainly observed through the upper 100 m layer,
while below this layer seasonal variations of the parameters were minor. Vertical structure of the temperature in the southern
coastal waters of the Caspian Sea is characterized by a significant seasonal thermocline between 20–50 m depths with vertical
variation in temperature about 16°C in midsummer (August). Decrease of the thermocline occurs with the general cooling of
the air and sea surface water, and deepening of the mixed layer during late of autumn and winter. Seasonal averages of the
salinity were estimated in a range of 12.27–12.37 PSU. The structure of thermocline and pycnocline indicated agreement between
changes of temperature and density of seawater. Seasonal pycnocline was observed in position of the thermocline layer. 相似文献
976.
Ananiev R. A. Dmitrevsky N. N. Roslyakov A. G. Chernykh D. V. Moroz E. A. Zarayskaya Y. A. Semiletov I. P. 《Oceanology》2022,62(1):127-132
Oceanology - The emission of natural gas from the seafloor to the surface in shelf areas of the Arctic seas is of increasing interest among researchers. Recently, various types of acoustic... 相似文献
977.
Radziminovich Ya. B. Filippova A. I. Gileva N. A. Melnikova V. I. 《Izvestiya Atmospheric and Oceanic Physics》2022,58(8):936-953
Izvestiya, Atmospheric and Oceanic Physics - We study in detail the source parameters, seismotectonic position, and macroseismic effects of the February 3, 2016, earthquake that occurred in the... 相似文献
978.
P. Cobo C. Ranz A. Fernández M. Cuesta D.K. Anthony M. Siguero 《Marine Geophysical Researches》2005,26(2-4):87-95
Vertical resolution is of fundamental importance in sonar exploration and is directly related to the duration of the acoustic
pulse generated by the transducer. The shorter the radiated pulse, the higher the vertical resolution. Many sub-bottom profiling
sonar systems use piezoelectric transducers because they are reversible and well understood. Piezoelectric projectors are
normally resonant transducers, which are intrinsically narrowband. A piezoelectric transducer is usually driven by a tone-burst.
However, it is possible to use Fourier techniques to find a pre-compensated electrical driving function so that the transducer
radiates a prescribed wider band acoustic waveform. This technique can be applied to synthesize zero-phase cosine-magnitude,
Gaussian, and bionic pulses, with a conventional sandwich transducer. Zero-phase cosine-magnitude waveforms provide minimum
length pulses (and therefore maximum resolution) within a prescribed frequency band.The aim of this paper is to illustrate
the synthesis of wideband acoustic pulses using an underwater piezoelectric projector. The conventional acoustic waveform
radiated when a Tonpiltz transducer is transiently excited using a “click” and allows its frequency response function to be
measured. This function is used to design the electrical signal which then drives the transducer so that it radiates the shortest
pulse compatible with its mechanical response. The significant resolution enhancement of the waveform shaping process is illustrated
by its application to a sediment wedge model. 相似文献
979.
980.
Pautet L. Tesei A. Guerrini P. Pouliquen E. 《Oceanic Engineering, IEEE Journal of》2005,30(4):912-920
Iterative Time Reversal (TR) procedures have been demonstrated to be successful in detecting scatterers even in a highly reverberant environment. The success of the method is attributable to a Time Reversal Mirror (TRM) consisting of an array of transceivers that allows one to reconstruct and reverse-propagate wavefronts of interest. This paper deals with the limiting case of a TRM reduced to a single transceiver, tested using a tank experiment with three scattering objects in free-field conditions. It is shown that it is possible to excite a resonance between the TR operator and the strongest mode of the target in the bandwidth of insonification. A simple free-field scattering model is used to study the mechanisms of convergence and to drive the physics-based analysis of data. 相似文献