Possible influence of Gondwanan glaciation on low-latitude carbonate sedimentation and trans-equatorial faunal migration: the lower Permian of South China

Peculiar Early Permian palaeontological and sedimentological features are reviewed from South China, including characteristic Early Permian cold-water Gondwanan brachiopod taxa and faunas from Sichuan and Guizhou provinces, widespread rosettes and irregular aggregates of calcite prisms ('Chrysanthemum Stones') within the Qixia limestones, and lack of significant Early Permian reef buildups. The occurrences of these features are at odds with the currently widely held view that South China was located in a palaeotropical, warm-water setting throughout the Permian and hence harboured a highly diverse shallow marine biota. In this paper, I propose a working hypothesis, suggesting that influence of at least cool water masses may have intermittently occurred in South China during the Early Permian, which facilitated the formation of the cool water-influenced palaeontological and sedimentological features and promoted the interchanges of cool to cold water marine faunas between the Gondwanan and Boreal Realms. These cool water masses may have been transported to low-latitude regions as deep currents from northern and eastern shelves of Gondwanaland and upwelled along the western coast of South China as well as within the relatively deep-water basins of central South China. Prevalence of these meridional, north-directed deep cold water currents during the Early Permian may have been related to the glaciation event of Gondwanaland. An alternative and/or additional source of cooling may have also originated from strong easterly palaeoequatorial boundary currents operating within the Palaeotethys at times during the Early Permian, inducing and/or enhancing upwelling of cool to cold water masses in the eastern Palaeotethys. This latter scenario is analogous to the occasional 'La Nina' effect (opposite to the 'El Nino' effect) at the equatorial belt of the modern Pacific Ocean.

Climate as a driver of population variability in breeding Gentoo Penguins (Pygoscelis papua) at the Falkland Islands

Detecting and predicting how populations respond to environmental variability are eminent challenges in conservation research and management. This is particularly true for wildlife populations at high latitudes, many of which demonstrate changes in popula

Relationship between long-term environmental fluctuations and diving effort of female Australian fur seals

For predators foraging within spatially and temporally heterogeneous marine ecosystems, environmental fluctuations can alter prey availability. Using the proportion of time spent diving and foraging trip duration as proxies of foraging effort, a multi-year dataset was used to assess the response of 58 female Australian fur seals Arctocephalus pusillus doriferus to interannual environmental fluctuations. Multiple environmental indices (remotely sensed ocean colour data and numerical weather predictions) were assessed for their influence on inter-annual variations in the proportion of time spent diving and trip duration. Model averaging revealed strong evidence for relationships between 4 indices and the proportion of time spent diving. There was a positive relationship with effort and 2 yr-lagged spring sea-surface temperature, current winter zonal wind and southern oscillation index, while a negative relationship was found with 2 yr-lagged spring zonal wind. Additionally, a positive relationship was found between foraging trip duration and 1 yr-lagged spring surface chlorophyll a. These results suggest that environmental fluctuations may influence prey availability by affecting the survival and recruitment of prey at the larval and post-larval phases while also affecting current distribution of adult prey.

Resistance and resilience: Can the abrupt end of extreme drought reverse avifaunal collapse?

Aim: Climate change is expected to increase the frequency and intensity of extreme climatic events, such as severe droughts and intense rainfall periods. We explored how the avifauna of a highly modified region responded to a 13-year drought (the 'Big Dry'), followed by a two-year period of substantially higher than average rainfall (the 'Big Wet'). Location: Temperate woodlands in north central Victoria, Australia. Methods: We used two spatially extensive, long-term survey programmes, each of which was repeated three times: early and late in the Big Dry, and in the Big Wet. We compared species-specific changes in reporting rates between periods in both programmes to explore the resistance (the ability to persist during drought) and resilience (extent of recovery post-drought) of species to climate extremes. Results: There was a substantial decline in the reporting rates of 42-62% (depending on programme) of species between surveys conducted early and late in the Big Dry. In the Big Wet, there was some recovery, with 21-29% of species increasing substantially. However, more than half of species did not recover and 14-27% of species continued to decline in reporting rate compared with early on in the Big Dry. Species' responses were not strongly related to ecological traits. Species resistance to the drought was inversely related to resilience in the Big Wet for 20-35% of the species, while 76-78% of species with low resistance showed an overall decline across the study period. Conclusions: As declines occurred largely irrespective of ecological traits, this suggests a widespread mechanism is responsible. Species that declined the most during the Big Dry did not necessarily show the greatest recoveries. In already much modified regions, climate extremes such as extended drought will induce on-going changes in the biota. © 2014 John Wiley & Sons Ltd.

Linking nitrogen sources utilised by seagrass in a temperate marine embayment to patterns of seagrass change during drought

Reductions in the extent of seagrass Zostera nigricaulis coverage in Port Phillip Bay (PPB), Australia, between 2000 and 2011 coincided with a prolonged period of drought (1997 to 2009) characterized by decreases in freshwater and nutrient inputs. This led us to hypothesize that patterns of seagrass expansion and decline in PPB may be linked to nutrient availability. Seagrasses in PPB can make use of a range of different nitrogen (N) sources depending on their relative availability. Accordingly, there is a need to identify the origin of the N utilised by seagrasses in order to understand how changes in the availability of nutrients from various sources may influence seagrass growth. This study used stable isotope analysis to estimate the contribution of different sources of N to seagrass growth in different parts of PPB. Source modelling indicated that regional patterns of N source utilisation matched changes in seagrass extent from 2000 to 2011. Regions in which seagrass declined contained a similar array of sources, including significant contributions from the catchment area, whereas regions where seagrass areas remained unchanged were largely dependent on a single N source (either fixation/recycled or sewage-derived). We propose that reductions in N from the catchment during the drought may have contributed to the decline of seagrasses in regions where N from the catchment is an important source. This finding is likely to have implications for the growth, distribution and resilience of Z. nigricaulis seagrass in PPB as well as in other parts of its range in southern Australia.