Holocene precipitation change in different monsoon sub-regions (time-slices and transient data) simulated by different global climate models, with links to model results

The recently proposed global monsoon hypothesis interprets monsoon systems as part of one global-scale atmospheric overturning circulation, implying a connection between the regional monsoon systems and an in-phase behaviour of all northern hemispheric monsoons on annual timescales (Trenberth et al., 2000). Whether this concept can be applied to past climates and variability on longer timescales is still under debate, because the monsoon systems exhibit different regional characteristics such as different seasonality (i.e. onset, peak, and withdrawal). To investigate the interconnection of different monsoon systems during the pre-industrial Holocene, five transient global climate model simulations have been analysed with respect to the rainfall trend and variability in different sub-domains of the Afro-Asian monsoon region. Our analysis suggests that on millennial timescales with varying orbital forcing, the monsoons do not behave as a tightly connected global system. According to the models, the Indian and North African monsoons are coupled, showing similar rainfall trend and moderate correlation in rainfall variability in all models. The East Asian monsoon changes independently during the Holocene. The dissimilarities in the seasonality of the monsoon sub-systems lead to a stronger response of the North African and Indian monsoon systems to the Holocene insolation forcing than of the East Asian monsoon and affect the seasonal distribution of Holocene rainfall variations. Within the Indian and North African monsoon domain, precipitation solely changes during the summer months, showing a decreasing Holocene precipitation trend. In the East Asian monsoon region, the precipitation signal is determined by an increasing precipitation trend during spring and a decreasing precipitation change during summer, partly balancing each other. A synthesis of reconstructions and the model results do not reveal an impact of the different seasonality on the timing of the Holocene rainfall optimum in the different sub-monsoon systems. They rather indicate locally inhomogeneous rainfall changes and show, that single palaeo-records should not be used to characterise the rainfall change and monsoon evolution for entire monsoon sub-systems.

At surface behaviour data of juvenile southern elephant seals from Marion Island between 2001 and 2006 with links to datasets

Marine mammals forage in dynamic environments characterized by variables that are continuously changing in relation to large-scale oceanographic processes. In the present study, behavioural states of satellite-tagged juvenile southern elephant seals (n = 16) from Marion Island were assessed for each reliable location, using variation in turning angle and speed in a state-space modelling framework. A mixed modelling approach was used to analyse the behavioural response of juvenile southern elephant seals to sea-surface temperature and proximity to frontal and bathymetric features. The findings emphasised the importance of frontal features as potentially rewarding areas for foraging juvenile southern elephant seals and provided further evidence of the importance of the area west of Marion Island for higher trophic-level predators. The importance of bathymetric features during the transit phase of juvenile southern elephant seal migrations indicates the use of these features as possible navigational cues.

(Table 1) Diving behaviour of male Adélie penguins (Pygoscelis adeliae) with and without corticosterone implants at Pointe Géologie

The amount of energy that organisms can allocate to self-maintenance and/or reproduction largely depends on their foraging strategies. Because of corticosterone (CORT) involvement in the control of energy metabolism, food intake and locomotor activity, recent studies have sought to demonstrate the role of this hormone in foraging decisions and performance. Moreover, considerable recent advances in animal-attached loggers now allow the study of behaviour in free-living animals. In order to assess the effects of CORT administration on the foraging behaviour of free-living Adelie Penguins Pygoscelis adeliae, we studied a group with CORT implants and a control group without CORT implants, by attaching time-depth recorders to the two groups and monitoring them throughout up to seven consecutive foraging trips during the guard stage (in Adelie Land, Antarctica). We found that foraging trips duration was similar between both groups. Dive durations, time spent at the bottom phase of dives, and the number of undulations per dive of CORT-implanted birds were all significantly higher than those of controls. However, CORT-implanted birds performed fewer dives overall (ca. 4,400) than controls (ca. 6,250) and spent many (13 and 6 times for penguins #3 and #4, respectively) long periods (>3 h) without diving. The low foraging effort and long resting periods support the view that CORT-implanted birds probably gained less energy than did the control birds. CORT treatment appears then to result in redirecting bird behaviour from costly activity (i.e. reproduction) to a behaviour promoting the preservation of energy reserves. Future studies are therefore needed to assess body condition and reproductive success of CORT-manipulated birds in parallel with the recording of their diving performances.

Porewater and solid-phase phosphorus geochemistry in surface sediments of sediment core GeoB9510-3, GeoB9518-4 and GeoB9519-6

Despite intensive research on the different domains of the marine phosphorus (P) cycle during the last decades, frequently discussed open questions still exist especially on controlling factors for the benthic behaviour of P and its general distribution in sediment-pore water systems. Steady state or the internal balance of all relevant physical and (bio)geochemical processes are amongst the key issues. In this study we present and discuss an extended data set from surface sediments recovered from three locations on the NW African continental slope. Pore water data and results from sequential sediment extractions give clear evidence to the well-known close relationship between the benthic cycles of P and iron. Accordingly, most of the dissolved phosphate must have been released by microbially catalyzed reductive dissolution of iron (oxhydr)oxides. However, rates of release and association of P and iron, respectively, are not directly represented in profiles of element specific sediment compositions. Results from steady-state based transport-reaction modelling suggest that particle mixing due to active bioturbation, or rather a physical net downward transport of P associated to iron (oxyhydr)oxides, is an essential process for the balance of the inspected benthic cycles. This study emphasizes the importance of balancing analytical data for a comprehensive understanding of all processes involved in biogeochemical cycles.

Dive depth profile and at surface behaviour data of emperor penguins from Pointe Géologie, Adélie Land, Antarctica, from expedition DDU 2005

Adult male and female emperor penguins (Aptenodytes forsteri) were fitted with satellite transmitters at Pointe-Géologie (Adélie Land), Dumont d'Urville Sea coast, in November 2005. Nine of 30 data sets were selected for analyses to investigate the penguins' diving behaviour at high resolution (doi:10.1594/PANGAEA.633708, doi:10.1594/PANGAEA.633709, doi:10.1594/PANGAEA.633710, doi:10.1594/PANGAEA.633711). The profiles are in synchrony with foraging trips of the birds during austral spring (doi:10.1594/PANGAEA.472171, doi:10.1594/PANGAEA.472173, doi:10.1594/PANGAEA.472164, doi:10.1594/PANGAEA.472160, doi:10.1594/PANGAEA.472161). Corresponding high resolution winter data (n = 5; archived elsewhere) were provided by A. Ancel, Centre d'Ecologie et Physiologie Energétiques, CNRS, Strasbourg, France. Air-breathing divers tend to increase their overall dive duration with increasing dive depth. In most penguin species, this occurs due to increasing transit (descent and ascent) durations but also because the duration of the bottom phase of the dive increases with increasing depth. We interpreted the efficiency with which emperor penguins can exploit different diving depths by analysing dive depth profile data of nine birds studied during the early and late chick-rearing period in Adélie Land, Antarctica. Another eight datasets of dive depth and duration frequency recordings (doi:10.1594/PANGAEA.472150, doi:10.1594/PANGAEA.472152, doi:10.1594/PANGAEA.472154, doi:10.1594/PANGAEA.472155, doi:10.1594/PANGAEA.472142, doi:10.1594/PANGAEA.472144, doi:10.1594/PANGAEA.472146, doi:10.1594/PANGAEA.472147), which backup the analysed high resolution depth profile data, and dive depth and duration frequency recordings of another bird (doi:10.1594/PANGAEA.472156, doi:10.1594/PANGAEA.472148) did not match the requirement of high resolution for analyses. Eleven additional data sets provide information on the overall foraging distribution of emperor penguins during the period analysed (doi:10.1594/PANGAEA.472157, doi:10.1594/PANGAEA.472158, doi:10.1594/PANGAEA.472162, doi:10.1594/PANGAEA.472163, doi:10.1594/PANGAEA.472166, doi:10.1594/PANGAEA.472167, doi:10.1594/PANGAEA.472168, doi:10.1594/PANGAEA.472170, doi:10.1594/PANGAEA.472172, doi:10.1594/PANGAEA.472174, doi:10.1594/PANGAEA.472175).