Heather A. Outred

The distribution and fate of arsenic in the Waikato River system, North Island, New Zealand

Arsenic levels were determined in waters, sediments, aquatic macrophytes and other organisms taken from the Waikato River system, North Island, New Zealand. All water samples contained elevated lev...

Germination requirements of New Zealand native plants: a review

Abstract A review of our knowledge of the germination requirements of seeds of indigenous New Zealand plants is presented. A search of the literature reveals information, in varying detail, on only 113 species, some 5% of the estimated total of vascular plants, most of them from forest habitats. The New Zealand flora, much of it now endangered, represents a unique genetic resource. There is an urgent need for research in seed biology if this resource is to be conserved and maintained. Germination characteristics are tentatively assigned to the physiological groupings of vivipary, recalcitrance, quiescence, and dormancy. With regard to the latter, evidence is reviewed for the roles of light, low temperature, after-ripening, inhibitors, and seed-coat imposed dormancy.

Mercury and arsenic in trout from the Taupo Volcanic Zone and Waikato River, North Island, New Zealand

ABSTRACTMercury and arsenic levels were determined in the flesh and livers of rainbow trout (Oncorhyncus mykiss Richardson) and brown trout (Salmo trutta L.) from lakes of the Taupo Volcanic Zone, and some locations on, or near, the Waikato River, North Island, New Zealand. All the fish sampled had measurable amounts of mercury in their flesh. Some trout from Lakes Rotorua, Rotoiti, and Rotomahana and trout from the Puwheto stream had flesh mercury concentrations above the World Health Organizations limit for mercury in foodstuffs. There were significant positive correlations between the flesh mercury concentration and the body weight and/or length of the trout. Brown trout taken from Puwheto had higher flesh mercury concentrations than rainbow trout taken from the same area. This may have been because the brown trout had a greater average length. Arsenic concentrations in the flesh of all the trout were of the same order of magnitude as the water from which they were taken and therefore pose no threat t...

Phaeoceros delicatus a new species of Anthocerotae from New Zealand

Abstract A new species of Phaeoceros, P. delicatus, is described from material collected in New Zealand. It is dioicous and is characterised by a costa with elongated cells, marginal gemmae, and spore ornamentation consisting of simple papillae on the proximal face and simple or multiple papillae on the distal face.

Seed storage and seed storage reserves in Chatham Island forget‐me‐not (Myosotidium hortensia, Boraginaceae)

Abstract Chatham Island forget‐me‐not is endemic to the Chatham Islands, New Zealand, where it is mainly confined to the outer islands. The conditions required to maintain seed viability during storage are not well understood and there are conflicting reports as to whether the seed will retain viability in storage. Seed of M. hortensia stored at 7.5% seed moisture content showed no decline in viability after 21 months, but seed stored at 9.5% seed moisture content showed a significant (P < 0.05) loss of viability after 9 months storage. The composition of the seed storage reserves of M. hortensia was assessed using transmission electron microscopy. The storage reserves were found to be predominately lipid (24%) and protein with no starch reserves detected. Gas chromatographic analysis of fatty acid methyl esters derived from the lipid storage reserves identified a high percentage (9%) of the commercially important γ‐linolenic (cis, cis, cis‐6, 9, 12‐octadecatrienoic) acid. The decline in seed viability at relatively low seed moisture content is typical of oil storage seeds and consistent with orthodox seed behaviour.

The mechanism of seed coat-imposed dormancy revealed by oxygen uptake in Chatham Island forget-me-not Myosotidium hortensia (Decne.) Baill.

ABSTRACT Chatham Island forget-me-not Myosotidium hortensia (Boraginaceae) is a monotypic genus endemic to the Chatham Islands of New Zealand. Myosotidium hortensia is threatened in its natural environment by introduced grazing animals and weeds. Further to this, the conservation and reintroduction efforts of M. hortensia are hindered by their dormant seeds. The dormancy is imposed by the seed coat but the underlying dormancy mechanisms are not well understood. Understanding the dormancy mechanisms in this species will help in revegetation efforts. This work aims to elucidate mechanisms by which the seed coat imposes dormancy in M. hortensia by determining the germination after manipulation of the seed coat and measuring changes in oxygen uptake in response to this manipulation. The structure of the seed coat was assessed using scanning electron microscopy and the presence or absence of lignin in the seed coat determined. As with other Boraginaceae, the seed coat of M. hortensia does not restrict water penetration into the seed. Oxygen uptake was 4.5 fold higher in decoated than in intact seed. There was no significant increase in oxygen uptake for the seeds when their seed coat had been pierced or pierced and resealed with vaseline. However, the germination rate, as measured by radicle emergence, was faster in these seeds. These findings, in addition to the structural analysis of the seed coat which revealed that the seeds have secondary thickening but no lignin, confirmed that mechanical constraint of embryo growth was preventing germination.