Zygmunt Klusek

The importance of prey aggregations to the distribution of Brünnich's guillemots in Storfjorden, Svalbard

We studied the influence of the distribution of prey and hydrographic fronts on the spatial distribution of foraging Brunnichs guillemots (Uria lomvia) in Storfjorden, southeastern Svalbard in late July 1992. Two large breeding colonies, comprising a total of 540000 individuals, were located adjacent to the study area, and large numbers of Brünnichs gullemots from these colonies foraged within the area, as well as to the south, outside of Storfjorden. Within the study area, most guillemots foraged on the west side of the fjord, coincident with a weak subsurface front between warm Atlantic water, which penetrated Storfjorden from the south, and cold Arctic water. Food samples from the guillemots collected in the study area contained primarily crustaceans (Parathemisto spp. and Thysanoessa inermis) and polar cod Boreogadus saida. Acoustic observations of prey were differentiated into two classes of signals, which we interpreted as originating from aggregated and dispersed organisms. The numbers of foraging guillemots were strongly correlated with the strength of echoes of the aggregated type, whereas correlations with dispersed echoes were consistently weaker. The distribution of foraging guillemots showed no significant correlations with either horizontal or vertical gradients of physical properties of the water column. Our finding that guillemots respond differently to aggregated and dispersed prey has important implications both for the interpretation of past work on the foraging ecology of marine birds, and for the management of fisheries.

Vertical distribution and diurnal migrations of krill — Euphausia superba Dana — from hydroacoustical observations, SIBEX, December 1983/January 1984

SummaryThe depth distributions of krill density with the resolution of 0.435 m has been obtained on the basis of SIBEX hydroacoustic data. Krill was observed to be mainly in a layer from 20 to 100 m with the maximum of biomass migrating from the near surface area at night to greater depths during day. The krill migration pattern can be described by the function: H(t)=A+Bcos (2πt/T+ϕ), where H is depth of the mass center of biomass, t-time, A-mean depth of krill occurrence, B-amplitude of diurnal changes, T=24 h and ϕ-phase of migration process. The parameters of migration pattern: A, B, T and ϕ depend on the body length of krill.

Statistical analysis of acoustic echoes from underwater meadows in the eutrophic Puck Bay (southern Baltic Sea)

In order to monitor the recovery of vegetation from pollution and the success of re-seeding efforts, acoustic echoes from the sea floor, covered and uncovered by underwater vegetation, were collected in Puck Bay (southern Baltic sea) using a 208 kHz Biosonics DT 4200 scientific echo sounder. The echo envelopes were examined and several of their parameters were recommended for further analysis. The possibility of using these parameters to distinguish between a bare sea floor and underwater meadows was tested. The parameters may be helpful in the identification of the species composition of the meadows and in accurate biomass assessment.

Nonlinear acoustical methods in the detection of gassy sediments

The applieation oj nonlinear backscattering oj aeoustieal signals in deteetion ojgas bubbles in subsurjaee layer oj sediment oj the Gulf oj Gdansk is presented. Gas bubbles concentration was estimated assuming that nonlinear scattering in soft sediments is similar as in water. Summary, difJerence and double harmonics generated only by gas bubbles were reeorded and used jor bubble density estimation. Comparisons oj the eoneentrations reeeived from difJerent nonlinear components show generally agreement in cafeulated bubble density distributions, although values oj densities acquired from almost identieal volumes in a single transmission differ.

Dependence of scattered acoustical signal intensity on the form of distribution of plankton concentration

Sounding of the plankton aggregation which consists of identical statistically uncorrelated particles by a plane monochromatic wave has been studied. Analytical formulas for scattered signal intensity and interference coefficient have been obtained for an arbitrary plankton spatial distribution form. The role of interference of waves scattered by individual plankton targets has been under investigation. The influence of the plankton probability density function form on the sounding signal mean intensity has also been considered.

Deep sea habitats in the chemical warfare dumping areas of the Baltic Sea

The Baltic Sea is a severely disturbed marine ecosystem that has previously been used as a dumping ground for Chemical Warfare Agents (CW). The presence of unexploded underwater ordnance is an additional risk factor for offshore activities and an environmental risk for the natural resources of the sea. In this paper, the focus is on descriptions of the marine habitat based on the observations arising from studies linked to the CHEMSEA, MODUM and DAIMON projects. Investigated areas of Bornholm, Gotland and Gdańsk Deeps are similarly affected by the Baltic Sea eutrophication, however, at depths greater than 70m several differences in local hydrological regimes and pore-water heavy metal concentrations between those basins were observed. During the lifespan of presented studies, we were able to observe the effects of Major Baltic Inflow, that started in December 2014, on local biota and their habitats, especially in the Bornholm Deep area. Reappearance of several meiofauna taxa and one macrofauna specimen was observed approximately one year after this phenomenon, however its ecological effects already disappeared in March 2017. According to our findings and to the EUNIS Habitat Classification, the three reviewed areas should be characterized as Deep Sea Muddy Sands, while the presence of suspicious bomb-like objects both beneath and on top of the sediments confirms their CW dumpsite status.

Results of Acoustic Research in the CM Deploying Areas

Short overview of problems connected with acoustic detection and recognition of chemical munition deployed in the Baltic Sea after the II WWW is demonstrated.

Ambient sea noise as the indicator of dynamic physical processes at the sea surface

It is well known that an ambient sea sound is generated by wind, mostly throughout the processes of wave breaking and accompanying injection of acoustically active air bubbles. The resulting sound level is highly correlated with wind speed and has consequently been propounded that the ambient sea noise can be used to estimate wind speeds. It has been proved that despite of significant scattering the accuracy is similar to other marine wind measurement techniques. Tentatively the acoustic ambient sea noise could be used also as an alternative technique for estimating a set of diverse dynamical processes like the wind wave energy dissipation, rain rate and rain type, and also as the indicator of bubbles presence. The simplicity of the passive acoustic buoys technology and sensors endurance to withstand the hard conditions in highly dynamic and corrosive environment make it very suitable technique. The measurements of the ambient sea noise in the Baltic Sea jointly with other parameters as wind speed, air bubbles entrainment, rain rate and wave field statistics were performed using autonomic hydroacoustic buoys. The measurements of ambient noise in a mid-frequency range (350–12500Hz) were carried out with the acoustic imaging of bubble plumes structure performed at 130 kHz to find associations between noise and parameters of bubble population. Relationships between bubble clouds parameters, the wind speed and the ambient sea noise were derived, providing a better way to predict a bubble population presence on the basis of the noise level. A good correlation quality between the wind speed and the ambient sound level is achieved by considering a sound propagation conditions in the area. The hydrophones should be deployed outside of the Baltic Seasonal Acoustic Waveguide — a subsurface one — during the winter/spring season and the deep water waveguide in the summer/autumn period. Using multisensory autonomic hydroacoustic buoy of the next generation, the noise and wind wave statistics were measured simultaneously including the registration of the noise from single breaking event to estimate breaking probability and intensity of the wave processes.