Dive depth and dive duration data of subadult and adult, male and female southern elephant seals from Marion Island between 2004 and 2008 with links to datasets

Sexual segregation in habitat use occurs in a number of animal species, including southern elephant seals, where differences in migration localities and dive behaviour between sexes have been recorded. Due to the extreme sexual size dimorphism exhibited by southern elephant seals, it is unclear whether observed differences in dive behaviour are due to increased physiological capacity of males, compared to females, or differences in activity budgets and foraging behaviour. Here we use a mixed-effects modelling approach to investigate the effects of sex, size, age and individual variation on a number of dive parameters measured on southern elephant seals from Marion Island. Although individual variation accounted for substantial portions of total model variance for many response variables, differences in maximum and targeted dive depths were always influenced by sex, and only partly by body length. Conversely, dive durations were always influenced by body length, while sex was not identified as a significant influence. These results support hypotheses that physiological capability associated with body size is a limiting factor on dive durations. However, differences in vertical depth use appear to be the result of differences in forage selection between sexes, rather than a by-product of the size dimorphism displayed by this species. This provides further support for resource partitioning and possible avoidance of inter-sexual competition in southern elephant seals.

Reference datasets and pollen record from sediment core YAK, Yakumo, SW Hokkaido

This study reconstructs middle and late Holocene vegetation and climate dynamics in the Oshima Peninsula, SW Hokkaido, using the published method of biome reconstruction and modern analogue technique applied to the Yakumo pollen record (42°17'03''N, 140°15'34''E) spanning the last 5500 years. Two previously published matrices assigning Japanese plant/pollen taxa to the major vegetation types (biomes) are tested using a newly compiled dataset of 78 surface pollen spectra from Hokkaido. With both matrices showing strengths and weaknesses in reconstructing cool mixed and temperate deciduous forests of Hokkaido, the results suggest the necessity to consider the whole list of identified terrestrial pollen taxa for generating robust vegetation reconstructions for northern Japan. Applied to the fossil pollen data, both biome-reconstruction approaches demonstrate consistently that oak-dominated cool mixed forest spread in the study region between 5.5 and 3.6 cal ka BP and was subsequently replaced by beech-dominated temperate deciduous forest. The pollen-based climate reconstruction suggests this change in the vegetation composition was caused by a shift from cooler and drier than present climate to warmer and wetter, similar to modern conditions about 3.6 cal ka BP. Comparing the pollen-based reconstruction results with the published marine records from the NW Pacific, the reconstructed vegetation and climate dynamics can be satisfactorily explained by the greater role played by the warm Tsushima Current in the Sea of Japan and in the Tsugaru Strait during the middle and late Holocene. An increase in sea surface temperatures west and south of the study site would favour air temperature rise and moisture uptake and cause an increase in precipitation and snow accumulation in the western part of Hokkaido during the late Holocene.

Late Eocene-earliest Miocene Sr isotopic reference section of DSDP Site 73-522

We present a revised calibration of Sr isotopes to the geomagnetic polarity timescale (GPTS) using closely spaced (~0.15 m.y. resolution) samples from the classic uppermost Eocene through lowermost Miocene section at Site 522, eastern South Atlantic. The Sr isotopic data are fit with two linear segments with a sharp change in slope at circa 27.5 Ma from 0.000038/m.y. (27.5 to 34.4 Ma) to 0.000051/m.y. (23.8 to 27.5 Ma). Regression analysis indicates that stratigraphic resolution ranges from ±1 m.y. (for one analysis) to ±0.6 m.y. (for three analyses) for the younger interval and ±1.2 m.y. (for one analysis) to ±0.7 m.y. (for three analyses) for the older interval, representing an increase in resolution from previous studies of ±1-2 m.y. The paleoceanographic significance of this change in slope is unclear. It occurs during an interval of intermittent Antarctic glaciation, between the Oi2a and Oi2b glaciations. The subsequent interval from circa 27 to 24 Ma appears to be an interval of minimal glaciation. Thus this observation does not support previous suggestions that increases in rates of Sr isotopic change are directly associated with the frequency of Antarctic glaciations. Rather, the increase in slope may be related to increased weathering associated with the "mid-Oligocene" glaciation.