The life cycle of Paracardicoloides yamagutii Martin, 1974 (Digenea: Sanguinicolidae)

The sanguinicolids Paracardicoloides yamagutii Martin, 1974 and Plethorchis acanthus Martin, 1975 were obtained from their definitive hosts, Anguilla reinhardtii Steindachner and Mugil cephalus Linnaeus (respectively) in the tributaries of the Brisbane River, Queensland, Australia. Two putative sanguinicolid cercariae were collected from a hydrobiid gastropod, Posticobia brazieri Smith, in the same waters. The two cercariae differ markedly in size and the form of their sporocysts. Both putative cercariae develop in the digestive gland of Po. brazieri. The ITS2 rDNA region from these sanguinicolids and a Clinostomum species (utilised as an outgroup due to the close morphological similarities between the cercarial stages of the Clinostomidae and the Sanguinicolidae) were sequenced and aligned. Comparison of the ITS2 sequences showed one cercaria to be that of P. yamagutii. This is the first sanguinicolid life history determined by a molecular method. P. yamagutii is the fourth sanguinicolid known to utilise a freshwater hydrobiid gastropod as its intermediate host. ITS2 rDNA is effective in distinguishing sanguinicolids at the species level.

Life Cycle Assessment (LCA) Applied to the Design of an Innovative Drying Process for Sewage Sludge

Most adverse environmental impacts result from design decisions made long before manufacturing or usage. In order to prevent this situation, several authors have proposed the application of life cycle assessment (LCA) at the very first phases of the design of a process, a product or a service. The study in this paper presents an innovative thermal drying process for sewage sludge called fry-drying, in which dewatered sludge is directly contacted in the dryer with hot recycled cooking oils (RCO) as the heat medium. Considering the practical difficulties for the disposal of these two wastes, fry-drying presents a potentially convenient method for their combined elimination by incineration of the final fry-dried sludge. An analytical comparison between a conventional drying process and the new proposed fry-drying process is reported, with reference to some environmental impact categories. The results of this study, applied at the earliest stages of the design of the process, assist evaluation of the feasibility of such system compared to a current disposal process for the drying and incineration of sewage sludge.

An analysis of changing management roles in small Australian services exporters in response to the stages in industry development

Life cycle models have become important in explaining the changing size structure of firms based on the carrying capacity of regions or industries. In particular, the population ecology model predicts stages of growth, maturity and eventually decline in the number of firms in an industry. There has been criticism of such models because of their focus on external variables as pre-determinants of the potential for enterprise development. This paper attempts to reconcile the external focus of the population ecology model with relevant internal management factors in enterprise development. A survey was conducted of Australian services exporters, and the results not only confirm the existence of four separate life cycle stages in the population ecology model, but also identify the external and internal variables that are strategically relevant at each of the stages. The findings provide potentially useful information in a range of contexts including the design of small business assistance as well a providing “guide posts” to entrepreneurs engaged in enterprise development.

Effects of the herbicide diuron on the early life history stages of coral

The effects of the herbicide diuron on the early life history stages of broadcast spawning and brooding corals were examined in laboratory experiments. Fertilisation of Acropora millepora and Montipora aequituberculata oocytes were not inhibited at diuron concentrations of up to 1000 mu gl(-1). Metamorphosis of symbiont-free A. millepora larvae was only significantly inhibited at 300 mu gl(-1) diuron. Pocillopora damicornis larvae, which contain symbiotic dinoflagellates, were able to undergo metamorphosis after 24h exposure to diuron at 1000 mu gl(-1). Two-week old P. damicornis recruits on the other hand were as susceptible to diuron as adult colonies, with expulsion of symbiotic dinoflagellates (bleaching) evident at 10 mu gl(-1) diuron after 96 h exposure. Reversible metamorphosis was observed at high diuron concentrations, with fully bleached polyps escaping from their skeletons. Pulse amplitude modulation (PAM) chlorophyll fluorescence techniques demonstrated a reduction in photosynthetic efficiency (Delta F/F'(m)) in illuminated P. dami- cornis recruits after a 2h exposure to 1 mu gl(-1) diuron. The dark-adapted quantum yields (F-v/F-m also declined, indicating chronic photoinhibition and damage to photosystem H. Crown Copyright (c) 2004 Published by Elsevier Ltd. All rights reserved.

The origin of the pelagobenthic metazoan life cycle: what's sex got to do with it?

The biphasic (pelagobenthic) life cycle is found throughout the animal kingdom, and includes gametogenesis, embryogenesis, and metamorphosis. From a tangled web of hypotheses on the origin and evolution of the metazoan pelagobenthic life cycle, current opinion appears to favor a simple, larval-like holopelagic ancestor that independently settled multiple times to incorporate a benthic phase into the life cycle. This hypothesis derives originally from Haeckel's (1874) Gastraea theory of ontogeny recapitulating phylogeny, in which the gastrula is viewed as the recapitulation of a gastracan ancestor that evolved via selection on a simple, planktonic hollow ball of cells to develop the capacity to feed. Here, we propose an equally plausible hypothesis that the origin of the metazoan pelagobenthic life cycle was a direct consequence of sexual reproduction in a likely holobenthic ancestor. In doing so, we take into account new insights from poriferan development and from molecular phylogenies. In this scenario, the gastrula does not represent a recapitulation, but simply an embryological stage that is an outcome of sexual reproduction. The embryo can itself be considered as the precursor to a biphasic lifestyle, with the embryo representing one phase and the adult another phase. This hypothesis is more parsimonious because it precludes the need for multiple, independent origins of the benthic form. It is then reasonable to consider that multilayered, ciliated embryos ultimately released into the water column are subject to natural selection for dispersal/longevity/feeding that sets them on the evolutionary trajectory towards the crown metazoan planktonic larvae. These new insights from poriferan development thus clearly support the intercalation hypothesis of bilaterian larval evolution, which we now believe should be extended to discussions of the origin of biphasy in the metazoan last common ancestor.

Pathology associated with endogenous development of haematozoa in birds from southeast Queensland

A study was undertaken on the pathology and associated schizont morphology of apicomplexan species of avian haematozoa. Some 32 birds from the families Artamidae, Meliphagidae, Oriolidae, Podargidae, Columbidae, Alcedinidae and Psittacidae were identified as having schizonts in various tissues. Based on blood stages observed, the probable relationship to tissue stages was considered. The majority of schizonts were referable to the genera Leucocytozoon and Haemoproteus . The comparative morphology of tissue stages previously described in the literature is discussed and the involvement of protozoa other than haematozoa considered. The naturally occurring infections in wild birds described in this study represent previously unreported data on the life-cycle stages involved. Some schizonts measured up to 640 mum. While pathological changes in some hosts were noticeable, in others no significant findings were observed. The role of endogenous stages in avian morbidity is discussed briefly.