Stomach content and parasite characteristics of M. scorpius from Frobisher Bay, Baffin Island

Shorthorn sculpin (Myoxocephalus scorpius) from Frobisher Bay, Baffin Island, is a slow growing long-lived species. A wide range of diet items were present in the stomachs of the shorthorn sculpins sampled but 2-3 diet items (amphipod species) comprised 99.5 % of total food consumed. These amphipods were present in the stomachs in similar proportions among all age classes of shorthorn sculpin. Several new host records for parasites were reported and mean numbers of parasite species increased with shorthorn sculpin age. The increased diversity of parasite species and higher d15N values in older/larger individuals suggest that their diets were more diverse and the prey items consumed had higher d15N values. By contrast, the value of d13C in dominant diet items masked the d13C values of minor diet items. We conclude that parasites and stable isotope values provide complementary data on feeding patterns of the shorthorn sculpin. The ubiquitous marine acanthocephalan, Echinorhynchus gadi, was found at high prevalences (87-100 %) and mean intensities (28-35), and were localized in the midgut. In contrast to other studies on acanthocephalans, E. gadi did not influence fish condition as measured by condition factor, liver somatic and gonado-somatic indices.

(Table 1) Grain size parameters of intertidal channel sand bars near Sylt, North-Frisian Wadden Sea

The aim of the present study is to investigate directional asymmetric properties and internal structures of the bedforms on the intertidal sand bars in comparison with the migration problems of the sand bodies developed in the channel systems of the tidal basin off the west coast of Schleswig-Holstein. The tidal channel sand bodies studied have 'V'-shaped outlines and are asymmetric in cross-section. Based on such knowledge it was hoped to understand and find possible factors for application to recent and ancient tidal depositional environments. The V-shaped intertidal channel sand bodies developed in the tidal environments between Sylt and Föhr Island are constantly migrating sand bars. The migration directions are in good agreement with the resultant vector mean directions of internal cross-stratification structures of asymmetric sedimentary bedforms. Finally, it is shown that the orientation of the apex of V-shaped sand bar as an equilibrium form alone can not indicate the migration direction, but that the orientation of the resultant vector mean of internal structures of sedimentary bedforms does indicate the migration direction. Based on the analyses of textural parameters of the migrating intertidal bar sands, it seems that sands of typical intertidal sand bars are negatively skewed and well sorted. The high rounding of quarz sand grains of these tidal channel sand bars seems to be an additional characteristical criterion for tidal depositional environments, as also indicated by Balazs and Klein (1972).

Geochemistry of metasedimentary units of the Cambro-Ordovician Ross Orogen in North Victoria Land and Oates Land, Antarctica

Metasediments in the three early Palaeozoic Ross orogenic terranes in northern Victoria Land and Oates Land (Antarctica) are geochemically classified as immature litharenites to wackes and moderately mature shales. Highly mature lithotypes with Chemical Index of Weathering values of >=95 are typically absent. Geochemical and Rb-Sr and Sm-Nd isotope results indicate that the turbiditic metasediments of the Cambro-Ordovician Robertson Bay Group in the eastern Robertson Bay Terrane represent a very homogeneous series lacking significant compositional variations. Major variations are only found in chemical parameters which reflect differences in degree of chemical weathering of their protoliths and in mechanical sorting of the detritus. Geochemical data, 87Sr/ 86Sr t=490 Ma ratios of 0.7120 - 0.7174, epsilonNd, t=490 Ma values of -7.6 to -10.3 and single-stage Nd-model ages of 1.7 - 1.9 Ga are indicative of an origin from a chemically evolved crustal source of on average late Palaeoproterozoic formation age. There is no evidence for significant sedimentary infill from primitive "ophiolitic" sources. Metasediments of the Middle Cambrian Molar Formation (Bowers Terrane) are compositionally strongly heterogeneous. Their major and trace element data and Sm-Nd isotope data (epsilonNd, t=500 Ma values of -14.3 to -1.2 and single-stage Nd-model ages of 1.7 - 2.1 Ga) can be explained by mixing of sedimentary input from an evolved crustal source of at least early Palaeoproterozoic formation age and from a primitive basaltic source. The chemical heterogeneity of metasediments from the Wilson Terrane is largely inherited from compositional variations of their precursor rocks as indicated by the Ni vs TiO2 diagram. Single-stage Nd-model ages of 1.6 -2.2 Ga for samples from more western inboard areas of the Wilson Terrane (epsilonNd, t=510 Ma -7.0 to -14.3) indicate a relatively high proportion of material derived from a crustal source with on average early Palaeoproterozoic formation age. Metasedimentary series in an eastern, more outboard position (epsilonNd, t=510 Ma -5.4 to -10.0; single-stage Nd model ages 1.4 - 1.9) on the contrary document stronger influence of a more primitive source with younger formation ages. The chemical and isotopic characteristics of metasediments from the Bowers and Wilson terranes can be explained by variable contributions from two contrasting sources: a cratonic continental crust similar to the Antarctic Shield exposed in Georg V Land and Terre Adélie some hundred kilometers west of the study area and a primitive basaltic source probably represented by the Cambrian island-arc of the Bowers Terrane. While the data for metasediments of the Robertson Bay Terrane are also compatible with an origin from an Antarctic-Shield-type source, there is no direct evidence from their geochemistry or isotope geochemistry for an island-arc component in these series.