Differences in benthic fauna and sediment among mangrove (Avicennia marina var. australasica) stands of different ages in New Zealand

Management of coastal environments requires understanding of ecological relationships among different habitats and their biotas. Changes in abundance and distribution of mangroves, like those of other coastal habitats, have generally been interpreted in terms of changes in biodiversity or fisheries resources within individual stands. In several parts of their range, anthropogenically increased inputs of sediment to estuaries have led to the spread of mangroves. There is, however, little information on the relative ecological properties, or conservational values, of stands of different ages. The faunal, floral and sedimentological properties of mangrove (Avicennia marina var. australasica) stands of two different ages in New Zealand has been compared. Older (>60 years) and younger (3-12 years) stands showed clear separation on the basis of environmental characteristics and benthic macrofauna. Numbers of faunal taxa were generally larger at younger sites, and numbers of individuals of several taxa were also larger at these sites. The total number of individuals was not different between the two age-classes, largely due to the presence of large numbers of the surface-living gastropod Potamopyrgus antipodarum at the older sites. It is hypothesized that as mangrove stands mature, the focus of faunal diversity may shift from the benthos to animals living on the mangrove plants themselves, such as insects and spiders, though these were not included in the present study. Differences in the faunas were coincident with differences in the nature of the sediment. Sediments in older stands were more compacted and contained more organic matter and leaf litter. Measurement of leaf chemistry suggested that mangrove plants in the younger stands were able to take up more N and P than those in the older stands. (C) 2003 Elsevier Science B.V. All rights reserved.

Trichostome ciliates from Australian marsupials. IV. Distribution of the ciliate fauna

Trichostome ciliates are associated with many different lineages of herbivorous mammals but there are few comparative studies of these associations in each lineage of herbivores. Here the occurrence of the ciliate fauna in a range of herbivorous marsupials (diprotodonts) is investigated and compared with that of ruminants. A total of 371 potential host animals, representing 33 species and 7 families, were examined for the presence of ciliates. The prevalence of endocommensal ciliates within individual host species varied between 0 and 100%. Of the different dietary groups of marsupials examined, only foregut (macropodids) and hindgut (vombatids) fermentative herbivores were found to harbour ciliates; carnivorous (dasyurids), omnivorous (peramelids) and midgut fermenting herbivores (phalangeroids) all lacked ciliates. The majority of ciliate species were oioxenic, several occurred in closely related hosts and some were able to colonise unnatural hosts in captive populations. Ciliate prevalences were found to vary at all levels: between hosts of different species, between conspecific hosts collected at different localities or seasons and between conspecific hosts at one collecting locality. The faunal composition of the 2 marsupial families which harboured ciliates differed greatly: the vombatid fauna was composed exclusively of amylovoracids whereas the macropodids harboured amylovoracids, polycostids and macropodiniids. In comparison to the ciliate fauna of ruminants, the fauna of macropodids is both depauperate and much more host specific. Low species richness in each host may be due to the large numbers of stomach nematodes in macropodids which compete with and may prey upon the ciliates within the stomach. The high levels of host specificity are probably due to different patterns of ciliate transmission in macropodids as they do not ruminate, eructate or feed indiscriminantly on pasture contaminated with saliva containing ciliates.

Epizootic activity of Murray Valley encephalitis and Kunjin viruses in an aboriginal community in the Southeast Kimberley region of Western Australia: Results of mosquito fauna and virus isolation studies

We undertook annual surveys of flavivirus virus activity in the community of Billiluna of Western Australia in the southeast Kimberley region between 1989 and 2001. Culex annulirostris was the dominant mosquito species, particularly in years of above average rains and flooding. Murray Valley encephalitis (MVE) virus was isolated in 8 of the 13 years of the study from seven mosquito species, but more than 90% of the isolates were from Cx. annulirostris. The results suggest that MVE virus is epizootic in the region, with activity only apparent in years with average or above average rainfall and increased numbers of Cx. annulirostris. High levels of MVE virus activity and associated human cases were detected only once (in 1993) during the survey period. Activity of MVE virus could only be partially correlated with wet season rainfall and flooding, suggesting that a number of other factors must also be considered to accurately predict MVE virus activity at such communities.