PL
 |
EN
Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 10

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
1
Content available Acoustic tracking dynamic phenomena in marine ecosystem
Orlowski A.
Hydroacoustics
|
2009
|
Vol. 12
167-180
EN
Acoustic information, collected in the form of measurements of integrated echo energiesrelated to time and 3D space has been applied at the Sea Fisheries Institute since 1981 to examine the rough statistical relationships between clupeoids distribution in the Baltic and the relevant environmental factors. In this paper it is shown that the data collected can be also applied for very detail observation of dynamic phenomena in marine ecosystem. Two differentiated case studies were selected to show new acoustic applications in specific areas of oceanographic research. In the first case spatial characteristics of fish diel vertical migration in the southern Baltic was surveyed and analysed for the period 1994-2007, against the environmental background. In the second case acoustic sounding was applied to quantify ebullition of methane from Baltic sediments. Both phenomena are strongly dependent on climatic variability. For both cases the final characteristics of the phenomenon was given in the form of video frames, expressing the processes in time. Unique method of echo-recording transformation into video frames was described and applied to analyse the process of ebullition of methane from the seabed.
2
Content available Sources of the variability of acoustic response of clupeoids in the Baltic
Orlowski A.
Hydroacoustics
|
2008
|
Vol. 11
313-328
EN
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.
3
Content available remote Acoustic seabed classification applied to Baltic benthic habitat studies: a new approach
Orlowski A.
Oceanologia
|
2007
|
No. 49 (2)
229-243
EN
The application of acoustic methods for the classification of bottom habitats is based mostly on the analysis of measured parameters without relating them to the bathymetric structure. Geological complexity and biological patterns are closely related to bathymetry. This paper presents a new approach to the acoustic classification of bottom habitats in that it combines the distribution of a selected acoustic parameter with its bathymetric structure. The hypothetical effective angle of a bottom echo ?'/2, corresponding to its normalised length, was the acoustic parameter applied. This parameter broadly characterises the complex acoustic reflecting and scattering properties of the seabed. Its highest values correspond to a layered bottom consisting of soft sediment. The southern Baltic area was classified by a direct comparison of two factors measured acoustically: the statistical distribution of ?'/2, and the correlated depth structure within selected standard regular geographical areas (15' latitude and 30' longitude) which the total area was divided into. The area size was matched with the density of the measurements collected. The same factors were also estimated for the whole southern Baltic. The study was based on soundings collected on board r/v "Baltica" during regular acoustic surveys in 1995-2003. The classification applied provides a new possibility of complex seabed identification and comparison of seabed structure dynamics, useful in benthic research and in the ecologically based administration of marine areas.
4
Content available Acoustic transects as classification units of the benthic habitat
Orlowski A.
Hydroacoustics
|
2007
|
Vol. 10
143-156
EN
The benthic habitat consists from abiotic (physiotope) and biotic (ecotope) components. The physiotope is characterized by seabed and associated waters properties. They influence on diversity of the flora and fauna. This process is directly dependent on the physical and chemical characteristics of the physiotope and its spatial structure. In conclusion the analysis of the benthic habitat along selected transects becomes more reasonable than limitation of the information to the static units (statistical rectangles). The paper describes 12 selected acoustic transects of the southern Baltic. For each transect nine parameters representing values of acoustic and environmental parameters were calculated and analyzed on the base of data collected in the autumns in the period 1995-2003 aboard the R.V. Baltica. Four parameters were characterizing seabed, next three hydrologic properties of water in the demersal zone, and last two – fish distribution. The parameters were estimated with the resolution of one nautical mile. Detail analysis of statistical and spatial distributions of all parameters was applied to classify and to compare the transects.
5
Content available remote Acoustic information applied to 4D environmental studies in the Baltic
Orlowski A.
Oceanologia
|
2006
|
No. 48 (4)
509-524
EN
Since 1981, acoustic information collected in the form of calibrated measurements of integrated echo energy has been applied at the Sea Fisheries Institute to observe the relationships between fish distribution and environmental factors. Data gathered in different seasons for each elementary distance unit (EDSU) at standardised depth intervals were compared to the values of selected environmental parameters measured in parallel. Acoustic, biological and hydrological data were correlated in space and transferred to the complex database, enabling 4D analysis of numerous factors characterising a wide range of fish behaviour. A number of methods and standards of comparisons are described to explain how to improve understanding of the relationship between 3D spatial environmental gradients and fish distributions. The results of various case studies, including the influence of hydrologic and seabed characterising factors, illustrate the practical application and validity of the methods. Particular attention is given to indicators of the dependence of local fish biomass density on the temperature structure in the sea.
6
Content available Acoustic classification of southern Baltic benthic habitat
Orlowski A.
Hydroacoustics
|
2006
|
Vol. 9
139-150
EN
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.
7
Content available Acoustic Reconnaissance of fish and environmental background in demersal zone in southern Baltic
Orlowski A., Kujawa A.
Hydroacoustics
|
2005
|
Vol. 8
137-146
EN
The paper describes results of studies based on measurements of the Sv distribution in 3m layer over the bottom in the southern Baltic area for the period 1995-2004. These are correlated with values of coincident bottom features, estimated on the basis of all available survey data. It is considered that values of Sv are proportional to demersal fish (herring, cod, flatfish) density. Seabed classification was based on analysis of duration of bottom echo recordings collected during the same series of surveys. Normalized (against the depth) bottom echo duration - Č’/2 was applied as 1D parameter characterizing seabed properties. Geographical distribution of this parameter and its dependence on other determined factors were analyzed. Studies of irregularities in fish distribution and its correlation to Č’/2 values were made. The paper gives a new method of acoustic classification of seabed and shows also some conclusions on coincidence of bottom features and environmental background.
8
Content available Acoustic reconnaissance of fish and evironmental background in demersal zone in Southern Baltic
Orlowski A.
Hydroacoustics
|
2004
|
Vol. 7
183-194
EN
The paper describes results of studies based on four-dimensional measurements of the Sv distribution in 3m layer over the bottom in the southern Baltic area for the period 1995-2002. These are correlated with values of coincident environmental factors: time, depth, water temperature, salinity and oxygen levels, bottom features, estimated on the basis of survey data and wide range of methods, elaborated by the author for fish behaviour studies. The purpose of the paper is to compare results collected during acoustic surveys in the Baltic and to estimate irregularities in fish distribution potentially influencing the results of fish bottom trawling in a sense of its application for demersal fish resources assessment.
9
Content available Acoustic experiment on diel fish behaviour cycle performed in the Gotland Deep
Orlowski A.
Hydroacoustics
|
2003
|
Vol. 6
19--30
EN
This paper describes the results of 24 h acoustic experiment based on three-dimensional measurements of the S; distribution of herring and sprat in the southern Baltic in October 2001. The experiment was based on a continuous (24h day) integration offish echoes using an EY500 echo sounder from a vessel with a constant speed of 8 knots, moving along the sides of a square equal to 4 n.mi., localized inside the specified area. Duration of the experiment was limited by deterioration of the weather conditions but nearly 300 ESDU samples were collected. These are correlated with values of coincident environmental factors: time, depth, water temperature, salinity and oxygen levels; estimated on the basis of survey data. Fish behaviour vs environmental factors is described by different macrosounding visualizations, statistical, and mathematical models. The purpose of the paper is to compare results of the experiment to the average characteristics of fish behaviour in the same basin, based on autumn studies over the period 1995-2001. General analysis was provided for the selected area of the Polish EEZ (south Gotland Deep), characterized by the greatest depth movements of fish diel migration. The most significant differences were found between fish migration pattern and diel stability of the acoustic response between these situations, specially during the sunset period.
10
Content available Acoustic studies on environmental pressure on 3D fish distribution in the Baltic
Orlowski A.
Hydroacoustics
|
2002
|
Vol. 5
29--40
EN
This paper describes results of enhanced version, of the macrosounding method to integrate acoustic data with environmental and biological parameters in a time and space scale, for use in marine ecosystem analyses. Fish distributions are shown by a vari-coloured topographical space, or time based, matrix of volume back-scattering strength (sv). The matrix is calculated for one or the series of surveys for each distance unit (ESDU) in standardized slices of insonified volume. Each sv visualization is accompanied by a parallel cross-section of the same space unit, which provides a distribution of the selected environmental parameter measured during the same survey. Charts of such parameters are produced with the same procedures as for sv. This presentation of multi-disciplinary data greatly improves recognition of time and space gradients. Analyses of data from multi-dimensional matrix calculated for individual transect improve interpretation and modeling of ecosystem characteristics. Application of the method was illustrated by examples, showing its practical use for data from 1994-2001 in the southern Baltic, collected during the autumn ICES acoustic surveys.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.