New records of the River Shark Glyphis (Carcharhinidae) reported from Cape York Peninsula, northern Australia

The distribution of the river shark Glyphis in northern Australia is extended with new records of occurrence in the Gulf of Carpentaria and a reassessment of historical survey data from Cape York Peninsula. Nine new specimens of Glyphis sp. A were collected in 2005 from the Weipa region on the Queensland coast of the Gulf of Carpentaria. A re-examination of archival records from 1978-86 marine and estuarine fish surveys in the Gulf of Carpentaria and along the northern Queensland East Coast allowed a further nineteen Glyphis specimens to be identified. Combined this gives twenty-eight new records of Glyphis specimens from the coasts of Cape York Peninsula, Queensland. Common habitat characteristics for all captures were turbid, shallow, fast running tidal water in the upper reaches of coastal rivers. The substrate was generally muddy and the rivers lined with mangrove. In all surveys the representation of Glyphis was low, being less than 1% of the total shark captures historically and 0.002 sharks 50 m net hour-1 in Weipa 2005. The size range captured was 1000-1800 mm total length historically and 705-1200 mm total length from Weipa 2005, with none recorded as sexually mature. Diagnostic characteristics of the Weipa specimens, identified as Glyphis sp. A, were: lower jaw teeth protruding and "spear-like"; second dorsal fin greater than half the height of the first dorsal fin; the snout relatively short and fleshy in the lateral view; pectoral fin ventral surface black in colouration; the precaudal vertebral count between 118 and 123; and the total vertebral count between 204 and 209.

The freezing characteristics of wheat at ear emergence

Wheat is occasionally exposed to freezing temperatures during ear emergence and can suffer severe frost damage. Few studies have attempted to understand the characteristics of freezing and frost damage to wheat during late development stages. It was clearly shown that wheat appears to have an inherent frost resistance to temperatures down to −5 °C but is extensively damaged below this temperature. Acclimation, whilst increasing the frost resistance of winter wheat in a vegetative state was incapable of increasing frost resistance of plants at ear emergence. It is proposed that the ability to upregulate frost resistance is lost once vernalisation requirement is fulfilled. Culms and ears of wheat were able to escape frost damage at temperatures below −5 °C by supercooling even to as low as −15 °C and evidence collected by infrared thermography suggested that individual culms on a plant froze as independent units during freezing with little or no cross ice-nucleation strategies to protect wheat from frost damage in the field appear to revolve around avoiding ice nucleation.

Stock structure of the blue threadfin (Eleutheronema tetradactylum) across northern Australia derived from life-history characteristics

Life history characteristics were used to determine the stock structure of the polynemid Eleutheronema tetradactylum across northern Australia. Growth, estimated from back-calculated length-at-age from sagittal otoliths, and length at sex change were estimated from samples collected from 12 different locations across western, northern and eastern Australia between 2007 and 2009. Comparison of back-calculated length-at-age, growth and length at sex change between locations revealed significant variation in the life-history characteristics of E. tetradactylum across northern Australia, with significant differences detected in 43 of 45 location comparisons. Differences in otolith size relative to fish length also existed amongst locations. No differences in other morphometric relationships were detected. The results of this study provide evidence for a high degree of spatial population subdivision for E. tetradactylum across northern Australia, the finding of which has implications for E. tetradactylum fisheries throughout its range, and provides a biological basis for spatial management of the species in Australia. (C) 2012 Elsevier B.V. All rights reserved.

Barley genotype expressing "stay-green"-like characteristics maintains starch quality of the grain during water stress condition

The identification of "stay-green" in sorghum and its positive correlation with yield increases has encouraged attempts to incorporate "stay-green"-like traits into the genomes of other commercially important cereal crops. However, knowledge on the effects of "stay-green" expression on grain quality under extreme physiological stress is limited. This study examines impacts of "stay-green"-like expression on starch biosynthesis in barley (Hordeum vulgare L.) grain under mild, severe, and acute water stress conditions induced at anthesis. The proportions of long amylopectin branches and amylose branches in the grain of Flagship (a cultivar without "stay-green"-like characteristics) were higher at low water stress, suggesting that water stress affects starch biosynthesis in grain, probably due to early termination of grain fill. The changes in long branches can affect starch properties, such as the rates of enzymatic degradation, and hence its nutritional value. By contrast, grain from the "stay-green"-like cultivar (ND24260) did not show variation in starch molecular structure under the different water stress levels. The results indicate that the cultivar with "stay-green"-like traits has a greater potential to maintain starch biosynthesis and quality in grain during drought conditions, making the "stay-green"-like traits potentially useful in ensuring food security. (C) 2013 Elsevier Ltd. All rights reserved.