The nature and extent of organisms in vessel sea-chests: A protected mechanism for marine bioinvasions

A total of 150 different organisms, including one plant species and 12 animal phyla were identified from sea-chests of 42 vessels visiting or operating in New Zealand between May 2000 and November 2004. Forty-nine percent of organisms were sessile, 42% mobile adults and the remaining 9% sedentary. Decapods were the most represented group with 19 species present among 79% of vessels. Forty percent of organisms were indigenous to New Zealand, 15% introduced, 10% non-indigenous, and 35% of unknown origin. Sea-chests have the potential to (1) transfer non-indigenous organisms between countries across oceanic boundaries; and (2) disperse both indigenous and introduced organisms domestically. The occurrence of adult mobile organisms is particularly significant and indicates that sea-chests may be of greater importance than ballast water or hull fouling for dispersing certain marine species. These findings emphasise the need to assess and manage biosecurity risks for entire vessels rather than different mechanisms (i.e., ballast water, hull fouling, sea-chests, etc.) in isolation.     

Activity budgets of New Zealand fur seals Arctocephalus forsteri during the breeding season

The activity budgets of territorial males, adult females, pups, and yearlings of the New Zealand fur seal Arctocephalus forsteri (Lesson, 1828) on Taumaka, Open Bay Islands, Westland, New Zealand (43° 52 S, 168° 53′ E) from 18 November 1974 to 30 January 1975 are described. Territorial males spent an average of 74.4% of their time lying down; 13.5% in a state of alertness; 4.8% on intrasexual and intersexual activities combined; and 7.3% on miscellaneous activities, including grooming, walking, and swimming. Equivalent figures for adult females, pups, and yearlings were: lying down (62.8%, 70.1%, and 66.6% respectively); alertness (4.9%, 2.8%, 6.8%); intrasexual and intersexual activities (1.1%, females only); miscellaneous (21%; 16%; 26.5%); female‐pup interactions (11%; 11.1%).

The activity budgets of all the seal classes changed as the breeding season progressed. Males spent more time alert early in the season when they were establishing and defending territories and procuring females. Intrasexual behaviour was prominent only in November and early December, whereas intersexual behaviour became more conspicuous during December, when females were in post‐partum oestrus. Females displayed little interest in intrasexual activity. Interactions with males ceased after copulation. Swimming was a prominent activity for females, as was suckling once pups were present. During the first few weeks of life pups mostly slept and suckled. Yearlings were present on the rookery only until 2 December, when they were rejected by females with new pups. Their predominant activity, when not lying down, was swimming (17.2%).     

Transient events in the COBE database simultaneous with gamma ray bursts

We are investigating the COBE DMR data at instances of known -ray bursts (GRBs) when any of the six DMR horn directions was coincident with the direction of a burst. The BATSE instrument on board GRO has detected 207 bursts during the eight-month period of overlap corresponding to the current release of COBE data. The odds of a GRB occurring within the DMR field of view are near one coincidence per year. Here we report on one such serendipitous observation in 1991, GRB 911226, for which a detailed analysis is currently in progress.     

A catchment scale evaluation of the SIBERIA and CAESAR landscape evolution models

Landscape evolution models provide a way to determine erosion rates and landscape stability over times scales from tens to thousands of years. The SIBERIA and CAESAR landscape evolution models both have the capability to simulate catchment–wide erosion and deposition over these time scales. They are both cellular, operate over a digital elevation model of the landscape, and represent fluvial and slope processes. However, they were initially developed to solve research questions at different time and space scales and subsequently the perspective, detail and process representation vary considerably between the models. Notably, CAESAR simulates individual events with a greater emphasis on fluvial processes whereas SIBERIA averages erosion rates across annual time scales. This paper describes how both models are applied to Tin Camp Creek, Northern Territory, Australia, where soil erosion rates have been closely monitored over the last 10 years. Results simulating 10 000 years of erosion are similar, yet also pick up subtle differences that indicate the relative strengths and weaknesses of the two models. The results from both the SIBERIA and CAESAR models compare well with independent field data determined for the site over different time scales. Representative hillslope cross‐sections are very similar between the models. Geomorphologically there was little difference between the modelled catchments after 1000 years but significant differences were revealed at longer simulation times. Importantly, both models show that they are sensitive to input parameters and that hydrology and erosion parameter derivation has long‐term implications for sediment transport prediction. Therefore selection of input parameters is critical. This study also provides a good example of how different models may be better suited to different applications or research questions. Copyright © 2010 John Wiley & Sons, Ltd and Commonwealth of Australia     

The extended dust emission around the nova GK persei

We have applied maximum entropy reconstruction methods to the IRAS observations of the nova GK Persei to examine the spatial distribution of the far-IR emission. We have discovered discrete regions of emission in a co-linear structure extending to 17 arcmin on either side of the binary system, supporting a stellar origin for the structure. We postulate that the evolved secondary is the progenitor of the circumbinary envelope.