The Baltic is a unique brakish sea. Its moderate salinity is the result of the fresh river water input and non-periodic inflows of salty, oxygenated waters from the North Sea. However, the balance continually fluctuates. What impact does that have on the sea?
Temperature of superficial water in the Ezcurra Inlet was measured from March 1989 to February 1990, with a use of a mercurial thermometer with accuracy +0.1°C. Temperature was measured usually once a month at selected points. Influence of various factors on temperature of superficial water was preliminarily analysed. Basing on these results, temperature distribution in the mentioned area was determined. Mean yearly temperatures for each station, average space temperatures on measurement days and mean yearly temperatures for the whole area of the Ezcurra Inlet were calculated.
Results of measurements of temperature and salinity of surface waters of the Hornsund (South Spitsbergen) carried out at a coastal point of the Isbjornhamna Bay during the winter expedition 1979/80 of the Polish Academy of Sciences are discussed. Courses of both parameters, their variability, mean values and distributions are analyzed.
Based on the results of CTD measurements (in situ) made during r/v „Oceania" cruises in the Norwegian and Greenland Seas in 1986—1988 selected aspects of termohaline structure and water dynamics of chosen regions of the seas were described. Examples of space-time variations of temperature and salinity fields were presented and water masses geostrophic transport on the limits of the Norwegian Sea (upon the Atlantic Ocean and the Barents Sea) was estimated.
In general, Antarctic marine bacteria are small, with biovolumes ranging from 0.139 to 0.204 μm-3 cell-1, but their total biomass in seawater is considerable due to relatively high numbers that approximate to 1020 cells km-3. Bacterial biomass becomes more concentrated closer to land. Our multi-year Antarctic studies demonstrated an average total bacterial biomass of 504 tons in Admirality Bay (24 km3) or 21 tons per 1 km3, versus 6.4 tons per 1 km3 in the open ocean. Strikingly, bacterial biomass reached 330 tons per 1 km3 of seawater at the sea-ice edge, as sampled in Goulden Cove in Admiralty Bay. Bacterial biomass in Admirality Bay, which we believe can be enriched by halotolerant and thermotolerant fresh water bacteria from glacial streams, is equal to or even exceeds that of the standing stock of krill (100-630 tons per bay) or other major living components, including phytoplankton (657 tons), flagellates (591 tons), and ciliates (412 tons). However, the bacterial biomass is exceeded by several orders of magnitude by non-living organic matter, which constitutes the basic bacterial carbon source. Factors regulating high bacterial abundance in the vicinity of land are discussed.
In the years 1987-1989, within the frames of the international program "Greenland Sea Project", the Institute of Oceanology of Polish Academy of Sciences carried out the oceanographic investigations in the energoactive zones of the Northern Atlantic. The paper presents some results of these investigations, characterizing interannual variability of aero- and hydrophysical fields and the causal connections between hydrological and hydrobiological anomalies. Main results of these investigations indicate that the summer season of 1988 was an anomaly in the region of confluence of Barents and Norwegian Seas. This result is irrefutably confirmed by biological data concerning species, and hydrophysical data, such as light attenuation coefficient, fluorescence, spatial distributions of water temperature, salinity, density and current velocity, as well as mass and heat fluxes. It arises from these information that the southern border of the confluence zone was normally the heat „source", while in 1988 it was the heat „sink". The results obtained indicate two reasons responsible for such a situation. The first is the anticyclonic eddy structure of cold Barents Sea waters, penetrating the confluence zone. The second reason seems to be a mechanism blocking the transport of Atlantic water masses through the transect between Faeroe and Shetland Islands.
The article presents the issues related to ecological security of the Baltic Sea. The issue was taken from the perspective of Poland as one of the Baltic States, and also as a Member State of the European Union. The authors discussed the mechanisms and legal instruments which are crucial for the ecological security of the Baltic Sea (i.e. Helsinki Convention of 1974, or Agenda 21 for the Baltic Sea Region “Baltic 21”). The importance of cross-border cooperation has also been emphasized as an essential element of the security policy in the Baltic Sea area. The article also indicated threats to the protection of Baltic waters, among others, eutrophication.
The shipping noise near channels and ports is an important contribution to the ambient noise level, and the depth of these sites is often less than 100 m. However less attention has been paid to the measurement in shallow water environments (Brooker, Humphrey, 2016). This paper presents extensive measurements made on the URN (underwater radiated noise) of a small fishing boat in the South China Sea with 87 m depth. The URN data showed that the noise below 30 Hz was dominated by the background noise. The transmission loss (TL) was modelled with FEM (finite element method) and ray tracing according to the realistic environmental parameters in situ. The discrepancy between the modelled results and the results using simple law demonstrates both sea surface and bottom have significant effect on TL for the shallow water, especially at low frequencies. Inspired by the modelling methodology in AQUO (Achieve QUieter Oceans) project (Audoly et al., 2015), a predicted model applied to a typical fishing boat was built, which showed that the URN at frequencies below and above 100 Hz was dominated by non-cavitation propeller noise and mechanical noise, respectively. The agreement between predicted results and measured results also demonstrates that this modelling methodology is effective to some extent.