Temat: Gotland - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Acoustic experiment on diel fish behaviour cycle performed in the Gotland Deep
Autorzy:: Orlowski, A.
Powiązania:: https://bibliotekanauki.pl/articles/332560.pdf
Data publikacji:: 2003
Wydawca:: Polskie Towarzystwo Akustyczne
Tematy:: acoustic experiment
Gotland Deep
echo sounder
Opis:: 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.
Źródło:: Hydroacoustics; 2003, 6; 19-30
1642-1817
Pojawia się w:: Hydroacoustics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Hydrographic and hydrochemical conditions in the Gotland Deep area between 1992 and 2003
Autorzy:: Nausch, G.
Matthaus, W.
Feistel, R.
Powiązania:: https://bibliotekanauki.pl/articles/48546.pdf
Data publikacji:: 2003
Wydawca:: Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:: nutrient pool
temperature
hydrography
hydrochemical condition
ventilation
nutrient distribution
bottom water
salinity
Baltic Sea
stagnation period
hydrographic condition
Gotland Deep
Opis:: The paper describes the hydrographic-hydrochemical development in the eastern Gotland Basin between the major saltwater inflows into the Baltic Sea in 1993 and 2003. This period is characterised by only low inflow activity. The most important hydrographic events were the effects of the very strong inflow in 1993 and the weak inflows in 1993/1994 and 1997. The 1993/1994 inflows led to deep-water renewal, a steep fall in deep-water temperatures, and increasing salinity. The effects of the inflow of very warm, saline and oxygen-rich water in autumn 1997 were observed in the deep water in 1998, resulting in temperatures rising to 7◦C. The recent renewal in spring 2003 is reflected in the decreasing temperature, higher salinity and improved ventilation of the bottom water. Changes in the redox conditions exert a considerable influence on the nutrient distribution. During stagnation periods, there is enrichment of phosphate and ammonium, while nitrate is absent. Thus, around 31 μmol l−1 ammonium and 7 μmol l−1 phosphate were measured prior to the water renewal in 2003. Deepwater ventilation results in lower phosphate concentrations of around 2 μmol l−1, the nitrification of ammonium and the occurrence of nitrate. For the observation period, an estimate of nutrients stored in the deep water was done for the eastern Gotland Basin. During the recent stagnation period, there was an increase of up to 150% in the phosphate pool below the halocline, whereas the pool of inorganic nitrogen compounds decreased to 80% compared with 1992 when the previous stagnation period had ended. Under specific circumstances, these unbalanced nutrients can be made available to the upper water layers and can induce large-scale blooms of algae, especially of cyanobacteria.
Źródło:: Oceanologia; 2003, 45, 4
0078-3234
Pojawia się w:: Oceanologia
Dostawca treści:: Biblioteka Nauki