RESUMEN

AIMS: This study explores the microbial diversity of sources which may influence boat microbial communities. We investigated the impact of dock, air and water microbial communities on the hull, transom and bilge microbial communities over the span of 11 days. METHODS AND RESULTS: Using source tracking software, we investigated the extent to which each of our potential sources (air, water and dock) influenced the overall microbial community. This study concluded that the dock impacted 14-64% of the hull and transom microbial community. Micro-organisms from the water were shown to impact 5·6% the bilge microbial community but had minimal impact on hull and transom microbial communities. Micro-organisms from the air had minimal impact in all areas of the boat. CONCLUSIONS: Our results demonstrate that micro-organisms from sources other than water can influence the microbial community of a boat, suggesting that terrestrial micro-organisms can impact the boat microbial community. SIGNIFICANCE AND IMPACT OF THE STUDY: Outside of ballast tanks, microbial diversity on boats is largely unexplored. While ballast water is widely recognized as a route for dispersal of allochthonous micro-organisms, comparatively little is known about the microbial diversity on other areas of the boat. If the organisms on a boat originate from sources other than water, there is potential that terrestrial micro-organisms could be dispersed by shipping activity.

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RESUMEN

Between 34 and 15 million years (Myr) ago, when planetary temperatures were 3-4 degrees C warmer than at present and atmospheric CO2 concentrations were twice as high as today, the Antarctic ice sheets may have been unstable. Oxygen isotope records from deep-sea sediment cores suggest that during this time fluctuations in global temperatures and high-latitude continental ice volumes were influenced by orbital cycles. But it has hitherto not been possible to calibrate the inferred changes in ice volume with direct evidence for oscillations of the Antarctic ice sheets. Here we present sediment data from shallow marine cores in the western Ross Sea that exhibit well dated cyclic variations, and which link the extent of the East Antarctic ice sheet directly to orbital cycles during the Oligocene/Miocene transition (24.1-23.7 Myr ago). Three rapidly deposited glacimarine sequences are constrained to a period of less than 450 kyr by our age model, suggesting that orbital influences at the frequencies of obliquity (40 kyr) and eccentricity (125 kyr) controlled the oscillations of the ice margin at that time. An erosional hiatus covering 250 kyr provides direct evidence for a major episode of global cooling and ice-sheet expansion about 23.7 Myr ago, which had previously been inferred from oxygen isotope data (Mi1 event).

RESUMEN

Glaciomarine sediments with middle Miocene microfaunal assemblages are exposed at the sea floor below the southern Ross Ice Shelf. Plio-Pleistocene sediments are not present. Post-Miocene glacial sediments may have been deposited but removed by relatively recent ice shelf grounding. A meager Recent microfauna is present in some core tops.