A ship!based transect survey was used to record bird abundance and the acous! tically determined biomass of presumed prey[ The _ve transects were divided into 22 segments\ each 7Ð00 km in length[ The resolution of the survey was 049 m\ and analyses of correlations between predators and prey were performed at length scales from 049 m to 8 km[ We di}erentiated acoustic signals into aggregated and dispersed categories according to the estimated horizontal distribution of presumed prey[ 2[ Foraging guillemots were consistently more strongly correlated with the aggregated prey than with dispersed prey over scales ranging from 049 m to 8 km[ Correlations were weak at small scales "049 m Ð 0 km# and increased and stabilized at scales of 1Ð 2 km[ The spatial scale at which we obtained a shift from weak to strong correlations between guillemots and their prey was similar to the scale at which the spatial variances in both guillemot and prey abundance were high[ 3[ Guillemots showed low correlations with prey at low prey densities[ Similarly\ correlations between guillemots and prey were low at low bird densities[ The data support the hypothesis that the birds associate with prey patches with densities above a certain threshold\ and that {regional| prey abundances a}ect local use of patches[ 4[ The numerical aggregative response curves between guillemot and prey density were classi_ed as being neither hyperbolic "type II# or sigmoidal "type III# within the range of prey densities observed in this study[ The aggregative response curves were sensitive to spatial scales\ which suggest that studies of response curves should be conducted at a range of spatial scales[ Key!words] aggregative response\ Bru à nnich|s guillemots\ foraging ecology\ scale dependence\ Uria lomvia[ Journal of Animal Ecology "0888# 57\ 59Ð61

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This paper synthesizes, compares, and discusses acoustic data pertaining to the presence of gas in sediments within the Polish Exclusive Economic Zone in the southern Baltic Sea, which are scattered among different journals, some of which are difficult to access and therefore have limited availability to a wider group of readers. It includes data collected between the 1970s and the present day, collected using different acoustic measurement devices. A majority of reported acoustic manifestations of gas presence in sediments in the Polish EEZ take the form of acoustic blanking followed by layer enhancement, acoustic turbidity, and increased acoustic energy absorption. The observed morphological structures related to gas presence are pockmarks (shallow and buried-17 km 2), gas-saturated sediments, gas pockets, and gas chimneys. The estimated total area of acoustic manifestation of shallow gas in the Polish EEZ is around 700 km 2. Geochemical analyses of surface sediments demonstrated strong correlation with acoustic data and revealed that methane occurs at relatively shallow depths compared with other regions of the Baltic Sea.

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