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Tytuł:
Sources of the variability of acoustic response of clupeoids in the Baltic
Autorzy:
Orlowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/331596.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
Baltic
variability of acoustic response
acoustic information
Opis:
Acoustic information, collected in the form of calibrated measurements of integrated echo energies, has been applied at the Sea Fisheries Institute since 1981 to examine the relationships between clupeoids distribution in the Baltic and the relevant environmental factors. Data were collected during different seasons for each elementary distance unit (EDSU) at standardised depth intervals and compared to the values of selected environmental parameters measured in parallel. Acoustic, biological and hydrological data were correlated temporally and spatially, then transferred to a comprehensive database, thereby enabling the 4D analysis of the factors characterising a wide range of fish behaviour. Selected characteristics describe the variability of environmental factors during the short- and long-term life cycles of clupeoids. Apart from the analysis of abiotic factors, specially prepared cross-sections of the herring in different stages of gonad maturity are presented. The aspects of variability have been described for their inclusion in the measuring and modelling herring and sprat target strength, particularly under the specific circumstances of the Baltic Sea.
Źródło:
Hydroacoustics; 2008, 11; 313-328
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustic evaluating the Baltic fish behaviour
Autorzy:
Orłowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/331676.pdf
Data publikacji:
1997
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Acoustic methods could play an important role in studies of fish group behaviour in relation to environmental factors, being one of the most promising tools of research of ecosystems. The paper presents new conceptions of treatment acoustic, biological and hydrological data collected during surveys of pelagic fish resources. A method of macrosounding was enriched by complex imaging of environmental factors for single transects. More developed version, called "matrix macrosounding", deslinied for description of selected cross-sections, characteristic for the Baltic ecosystem, was introduced and examples of its application for short-term or long-term ecological studies were given. Basic diel fish environmental preferences were estimated owing to correlating acoustic and hydrological data collected over the period 1981-1996 in the southern Baltic. In a consequence, preliminary models of day life-eycle of fish in relation to main environmental factors were formulated and applied for fish behavioural studies. Examples of fish behaviour models, determined for the autumn are shown.
Źródło:
Hydroacoustics; 1997, 1; 37-42
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of acoustic backscattering by southern Baltic herring
Autorzy:
Idczak, J.
Gorska, N.
Powiązania:
https://bibliotekanauki.pl/articles/331977.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
acoustic biomass estimation
Baltic herring
target strength
modelling approach
X-ray images
Opis:
Assessment of Baltic herring abundance can be carried out using acoustic techniques. Analysis of the relationship between the Baltic herring individual target strength, TS, and the total fish length, L, important for the acoustic assessment, showed the relationship to be dependent on the location of the study area. This finding motivated a detailed analysis of the relationship for the herring occurring in the southern Baltic ICES subdivisions 24, 25, and 26, in which Poland is responsible for the acoustic herring abundance assessment. The paper addresses the numerical analysis of the backscattering properties of the southern Baltic herring. The modelling approach used to study the backscattering was based on the Modal Series-Based Deformed Cylinder Model approximation. Details of the individual herring swimbladders were taken into account. Morphometric data necessary for the analysis was obtained from X-ray images of herring from the Polish coastal zone (ICES subdivision 26).
Źródło:
Hydroacoustics; 2016, 19; 145-152
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustic classification of southern Baltic benthic habitat
Autorzy:
Orlowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/332425.pdf
Data publikacji:
2006
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Seabed characteristics applied for classification was based on analysis of echo recordings collected aboard RV “Baltica” during regular surveys in 1995-2003 period. Hypothetical effective angle of a bottom echo č’/2, corresponding to its normalized length was applied to characterize complex seabed acoustic reflecting and scattering properties. The č’/2 values were determined for each EDSU. Classification of southern Baltic area was provided by comparison of two acoustically measured factors: statistical distribution of č’/2 and correlated depth structure within selected standard areas. Both factors are very closely related to biological characteristics of the benthic habitat. Joining them gives a wide possibility of differentiating the habitat by its basic ecological properties. The classification applied gave a unique identification and comparison of dynamics of seabed structures, useful for benthic surveys and helpful in ecologically friendly administration of the zone.
Źródło:
Hydroacoustics; 2006, 9; 139-150
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of microphytobenthos photosynthesis on the spectral characteristics of the signal reflected from Baltic sandy sediments
Autorzy:
Jaśniewicz, D.
Gorska, N.
Powiązania:
https://bibliotekanauki.pl/articles/332045.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
hydroacoustics
backscattering
microphytobenthos photosynthesis
Baltic Sea
Opis:
The use of hydracoustical techniques to classify benthic fauna and flora is one of the important challenges in present marine research. It is crucial to understand the microphytobenthos photosynthesis impact on the backscattering properties of the sea floor in the Baltic Sea, where the techniques are actively developed now. This motivated our study. The data used in the analysis was collected in the multiday laboratory experiment conducted in the frame of the grant of the National Science Centre, Poland (No. N306 773940). In this experiment, during changing light conditions (light/dark photocycles), the hydroacoustical backscattering data was acquired in the aquarium with a sandy bottom. The constant temperature and salinity conditions, typical for the Southern Baltic, were kept, and oxygen content was monitored. In this paper data collected at 280 kHz, was processed. It was studied how the energy of echo and power spectral density of the echo signal, are sensitive to the microphytobenthos photosynthesis.
Źródło:
Hydroacoustics; 2016, 19; 165-171
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Environmental effect on acoustic measurements of Baltic fish
Autorzy:
Orłowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/332258.pdf
Data publikacji:
2000
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Behaviour of fish is one of most potential sources of bias in fisheries acoustics. The paper describes methods and results of analyses of unique acoustic, hydrologic, and biologic data base collected by research vessels of Sea Fisheries Institute in the southern Baltic in the years 1989-1998. On the basis of numeric models of measurements, interactions between environmental and behavioural factors and fish acoustic response have been estimated. Significant influence of environmentally modulated fish behaviour on effective value of the acoustic back-scattering cross-section was found, described, and discussed. Results indicate a necessity of further research on fish target strength within separate periods of a diel cycle, to define more accurately biomass conversion factors or to eliminate from the surveys the periods of the day, characterized by high instability of fish acoustic properties. Models of environmental background of fish diel cycle can be also applied in wider ecological studies.
Źródło:
Hydroacoustics; 2000, 3; 161-168
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Backscattering properties of southern Baltic herring
Autorzy:
Idczak, J.
Kniaź - Kubacka, N.
Powiązania:
https://bibliotekanauki.pl/articles/332433.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Reliable TS(L) relationship is required to improve acoustic algorithms of abundance estimation of Baltic herring. The relationships, empirically obtained in different parts of the Baltic Sea, produce up to 8 dB – difference in the herring TS. In order to develop an accurate TS(L) relationship, it is important to analyze factors controlling the TS variability. The possible impact of the regional difference in the swimbladder morphometry, critical in the backscattering by fish, should be considered. The paper is addressed to the numerical analysis of the backscattering properties of the southern Baltic herring. The input morphometric data for the modelling were obtained basing on the X-ray image collection of the herring individuals caught in the Polish coastal zone (ICES Subdivision 26) in November 2011. The optimal methodology of the morphometry study, including the fish catch, transport, storage and the X-ray analysis has been developed. The backscattering sensitivity to the fish morphometry and the width of fish orientation distribution was shown.
Źródło:
Hydroacoustics; 2012, 15; 57-64
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Echosounder and ADCP investigation of Baltic fauna
Autorzy:
Schmidt, B.
Szczucka, J.
Powiązania:
https://bibliotekanauki.pl/articles/332586.pdf
Data publikacji:
2007
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The Baltic fauna is rather meagre, what is connected with their miserable habitat. The area of our investigation is a specific basin because of its land-locked location, brackish water and small depth. It is characterised by enormous diversity of time-variable hydrological conditions. All species of fauna are subjected to the continuous stress of having to adapt to rapid changes in the temperature and salinity of the surrounding water and are exposed to highly variable environment during their every-day vertical migration between the food-rich sea surface and safer deep. The purpose of this paper is to present the results of acoustic investigations of the live interior of the Baltic Sea by means of various acoustic instruments (echosounders and acoustic Doppler current meters). The interpretation of our acoustic images helps to understand the nature and behaviour of the sound scatterers.
Źródło:
Hydroacoustics; 2007, 10; 175-182
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ambient sea noise in the Baltic Sea – review of investigations
Autorzy:
Klusek, Z.
Powiązania:
https://bibliotekanauki.pl/articles/985805.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
A short review of results of the ambient sea noise investigations in the Baltic Sea is presented in the paper. Historical collected data on the ambient noise completed by different investigators at stations located in different Baltic Sea basins are provided and their results are discussed. Furthermore, results of latest ambient sea noise measurements performed with autonomous acoustic buoys are presented.
Źródło:
Hydroacoustics; 2011, 14; 75-82
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of diurnal variability of the Baltic Sound scattering layers
Autorzy:
Szczucka, J.
Powiązania:
https://bibliotekanauki.pl/articles/331614.pdf
Data publikacji:
1997
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Schools of fish, aggregations of plankton and concentrations of gas bubbles cause scattering and attenuation of sound waves. In the Baltic Sea, in some seasons and during some hours, at the thermo- and halocline depth there persist aggregations of small marine organisms registered in the range of lower ultrasound frequencies. Diurnal vertical migrations of biological objects (fish and plankton) are easily observed by echosounders. The possible reasons for this well known phenomenon are different: light changes, animal morphology, social behaviour, grazing, chasing for prey or escaping from predator. The present study aims to recognize diel and seasonal changeability of the zooplankton aggregations, to show some examples of vertical migration and to search for possible mechanisms of large differences between day and night measures of the total backscattered energy, integrated over the entire water column. In accordance with bioacoustic practice, the term zooplankton in this paper will be used for both zooplankton and micronekton.
Źródło:
Hydroacoustics; 1997, 1; 109-114
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Are the knudsen curves acceptable in the Baltic Sea?
Autorzy:
Klusek, Z.
Lisimenka, A.
Powiązania:
https://bibliotekanauki.pl/articles/332366.pdf
Data publikacji:
2006
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Results of ambient noise measurements performed in the southern part of the Baltic Sea are presented. An autonomous measurement buoy was deployed in two Baltic Deeps under dissimilar sound propagation conditions - at the Bornholm Deep in winter and at the Gdansk Deep in summer. The sound was registered and analyzed in the frequency range from 350 Hz up to 35 kHz. The parameters of dependence of the ambient noise sound pressure level versus wind speed were determined. It was found that the measured ambient noise spectrum level depends not only on wind speed and location but also on a depth of observation. The results show that the wind dependent ambient noise component in the Baltic Sea frequently does not match the Knudsen curves, and we have found that at some specific location sound level at low frequencies does not depend on wind. The collected data on the noise levels are discussed with other historical and contemporary data on the noise level in the Baltic Sea.
Źródło:
Hydroacoustics; 2006, 9; 77-84
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conditions for propagation wave of finite amplitude in the Southern Baltic
Autorzy:
Grelowska, G.
Powiązania:
https://bibliotekanauki.pl/articles/332544.pdf
Data publikacji:
2007
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
In order to improve the buried objects search capability, there is a need to investigate new techniques that will enable the detection, localization and classification of buried mines. Indeed, mines buried in marine sediments represent a severe threat, especially in coastal waters. More-over, an inventory of objects buried in harbor areas is necessary to assure the security of ships. Parametric sonars are the new class of devices that allow to penetrate the sea floor. However their efficiency depends strongly on natural conditions in the sea. The dependence is of great importance in the shallow sea with considerable changes of acoustical conditions during the year. The paper contains the results of research of effectiveness of nonlinear wave generation in the Southern Baltic conditions basing on in situ measurements of the hydrological parameters.
Źródło:
Hydroacoustics; 2007, 10; 69-74
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the acoustic backscattering by Baltic herring and sprat
Autorzy:
Gorska, N.
Idczak, J.
Powiązania:
https://bibliotekanauki.pl/articles/331955.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Accurate abundance estimate of Baltic clupeids, herring and sprat, is required for their sustainable exploitation. The understanding the sound backscattering of individual fish is important for employing the acoustical techniques, which are widely used in the estimation. The previous studies demonstrated that the improvement of the understanding is critical for the Baltic herring and sprat. It was the main motivation of the paper. The main objective was understanding the difference in acoustic backscattering by herring and sprat in the Baltic Sea. The study was based on a numerical modeling of backscattering by the individual fish. The model input data (morphometric parameters of fish) are obtained using available X-ray images of Baltic sprat and herring. The difference in the backscattered energy, backscattering directivity pattern, and the body contribution into the backscattering of the total fish was demonstrated for the considered species.
Źródło:
Hydroacoustics; 2010, 13; 89-100
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fractal characterisation of 30 kHz echoes from southern Baltic bottom
Autorzy:
Tęgowski, J.
Łubniewski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/331844.pdf
Data publikacji:
2000
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The fractal dimension of 30 kHz echo envelope is used for characterise the bottom sediment type in Southern Baltic Sea. Two methods of the echo waveform fractal dimension calculation were applied: the autocorrelation function log-log slope method and the power spectrum log-log slope method. The results are presented and compared. They show that fractal dimension of echo envelope describes well the bottom sediments morphology and may be used as a significant descriptor in the remote sea bed classification procedures.
Źródło:
Hydroacoustics; 2000, 3; 15-18
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustic backscattering characteristics of mytilus dulis trossulus (southern Baltic Sea)
Autorzy:
Gorska, N.
Kowalska, E.
Powiązania:
https://bibliotekanauki.pl/articles/332435.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Study of benthic habitats is significant from ecological and economical point of view. Non–invasive, rapid and relatively cheap methods of the habitat classification are required. It is the reason why the hydroacoustic classification techniques are developed. These techniques are sensitive to the seabed sediments type and the backscattering properties of the benthic habitats, and are developed for individual marine conditions. Last few years the hydroacoustic classification algorithms are developed for the Southern Baltic Sea. To improve the algorithms it is required to know the backscattering properties of the typical benthic individual and aggregated organisms. The main objective of the article is the study of the backscattering characteristics of benthic shelled animals Mytilus edulis trossulus, which is one of the dominant species in the southern Baltic Sea. The approach is based on the numerical modelling of the acoustic wave backscattering by the individual organisms and their aggregations and comparison of the modelling results with the measured backscattered data.
Źródło:
Hydroacoustics; 2012, 15; 49-56
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 30

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